@article{wang_shivanna_zheng_pham_forrest_yang_guan_space_kitagawa_zaworotko_2024, title={Ethane/Ethylene Separations in Flexible Diamondoid Coordination Networks via an Ethane-Induced Gate-Opening Mechanism}, volume={146}, ISSN={["1520-5126"]}, DOI={10.1021/jacs.3c13117}, abstractNote={Separating ethane (C2H6) from ethylene (C2H4) is an essential and energy-intensive process in the chemical industry. Here, we report two flexible diamondoid coordination networks, X-dia-1-Ni and X-dia-1-Ni0.89Co0.11, that exhibit gate-opening between narrow-pore (NP) and large-pore (LP) phases for C2H6, but not for C2H4. X-dia-1-Ni0.89Co0.11 thereby exhibited a type F-IV isotherm at 273 K with no C2H6 uptake and a high uptake (111 cm3 g-1, 1 atm) for the NP and LP phases, respectively. Conversely, the LP phase exhibited a low uptake of C2H4 (12.2 cm3 g-1). This C2H6/C2H4 uptake ratio of 9.1 for X-dia-1-Ni0.89Co0.11 far surpassed those of previously reported physisorbents, many of which are C2H4-selective. In situ variable-pressure X-ray diffraction and modeling studies provided insight into the abrupt C2H6-induced structural NP to LP transformation. The promise of pure gas isotherms and, more generally, flexible coordination networks for gas separations was validated by dynamic breakthrough studies, which afforded high-purity (99.9%) C2H4 in one step.}, number={6}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Wang, Shao-Min and Shivanna, Mohana and Zheng, Su-Tao and Pham, Tony and Forrest, Katherine A. and Yang, Qing-Yuan and Guan, Qingqing and Space, Brian and Kitagawa, Susumu and Zaworotko, Michael J.}, year={2024}, month={Feb}, pages={4153–4161} }
 @article{mohamed_elzeny_samuel_xu_malliakas_picard_pham_miller_hogan_space_et al._2024, title={Turning Normal to Abnormal: Reversing CO<sub>2</sub>/C2-Hydrocarbon Selectivity in HKUST-1}, volume={1}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.202312280}, abstractNote={Metal–organic frameworks (MOFs) can efficiently purify hydrocarbons from CO2, but their rapid saturation, driven by preferential hydrocarbon adsorption, requires energy‐intensive adsorption–desorption processes. To address these challenges, an innovative approach is developed, enabling control over MOF flexibility through densification and defect engineering, resulting in an intriguing inverse CO2/C2 hydrocarbon selectivity. In this study, the densification process induces the shearing of the crystal lattice and contraction of pores in a defective CuBTC MOF. These changes have led to a remarkable transformation in selectivity, where the originally hydrocarbon‐selective CuBTC MOF becomes CO2‐selective. The selectivity values for densified CuBTC are significantly reversed when compared to its powder form, with notable improvements observed in CO2/C2H6 (4416 vs 0.61), CO2/C2H4 (15 vs 0.28), and CO2/C2H2 (4 vs 0.2). The densified material shows impressive separation, regeneration, and recyclability during dynamic breakthrough experiments with complex quinary gas mixtures. Simulation studies indicate faster CO2 passage through the tetragonal structure of densified CuBTC compared to C2H2. Experimental kinetic diffusion studies confirm accelerated CO2 diffusion over hydrocarbons in the densified MOF, attributed to its small pore window and minimal interparticle voids. This research introduces a promising strategy for refining existing and future MOF materials, enhancing their separation performance.}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Mohamed, Mona H. and Elzeny, Islam and Samuel, Joshua and Xu, Wenqian and Malliakas, Christos D. and Picard, Yoosuf N. and Pham, Tony and Miller, Lenore and Hogan, Adam and Space, Brian and et al.}, year={2024}, month={Jan} }
 @article{castell_nikolayenko_sensharma_koupepidou_forrest_solanilla-salinas_space_barbour_zaworotko_2023, title={Crystal Engineering of Two Light and Pressure Responsive Physisorbents}, volume={3}, ISSN={["1521-3773"]}, DOI={10.1002/anie.202219039}, abstractNote={An emerging strategy in the design of efficient gas storage technologies is the development of stimuli-responsive physisorbents which undergo transformations in response to a particular stimulus, such as pressure, heat or light. Herein, we report two isostructural light modulated adsorbents (LMAs) containing bis-3-thienylcyclopentene (BTCP), LMA-1 [Cd(BTCP)(DPT)2] (DPT = 2,5-diphenylbenzene-1,4-dicarboxylate) and LMA-2 [Cd(BTCP)(FDPT)2] (FDPT = 5-fluoro-2-diphenylbenzene-1,4,dicarboxylate). Both LMAs underwent pressure induced switching transformations from non-porous to porous via adsorption of N2, CO2 and C2H2. LMA-1 exhibited multi-step adsorption while LMA-2 showed a single-step adsorption isotherm. The light responsive nature of the BTPC ligand in both frameworks was exploited with irradiation of LMA-1 resulting in a 55% maximum reduction of CO2 uptake at 298 K. This study reports the first example of a switching sorbent (closed to open) that can be further modulated by light.}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Castell, Dominic C. and Nikolayenko, Varvara I. and Sensharma, Debobroto and Koupepidou, Kyriaki and Forrest, Katherine A. and Solanilla-Salinas, Carlos J. and Space, Brian and Barbour, Leonard J. and Zaworotko, Michael J.}, year={2023}, month={Mar} }
 @article{pham_forrest_niu_tudor_starkey_wang_eddaoudi_rosi_orcajo_eckert_et al._2023, title={Cu-ATC <i>vs.</i> Cu-BTC: comparing the H<sub>2</sub> adsorption mechanism through experiment, molecular simulation, and inelastic neutron scattering studies}, volume={10}, ISSN={["2050-7496"]}, DOI={10.1039/d3ta04748b}, abstractNote={A combined experimental, inelastic neutron scattering (INS), and theoretical study of H2 adsorption was carried out in Cu-ATC and Cu-BTC, two metal{organic frameworks (MOFs) that consist of Cu2+ ions coordinated...}, journal={JOURNAL OF MATERIALS CHEMISTRY A}, author={Pham, Tony and Forrest, Katherine A. and Niu, Zheng and Tudor, Brant and Starkey, Chloe B. and Wang, Yue and Eddaoudi, Mohamed and Rosi, Nathaniel and Orcajo, Gisela and Eckert, Juergen and et al.}, year={2023}, month={Oct} }
 @article{nikolayenko_castell_sensharma_shivanna_loots_forrest_solanilla-salinas_otake_kitagawa_barbour_et al._2023, title={Reversible transformations between the non-porous phases of a flexible coordination network enabled by transient porosity}, volume={2}, ISSN={["1755-4349"]}, url={https://doi.org/10.1038/s41557-022-01128-3}, DOI={10.1038/s41557-022-01128-3}, abstractNote={Abstract Flexible metal–organic materials that exhibit stimulus-responsive switching between closed (non-porous) and open (porous) structures induced by gas molecules are of potential utility in gas storage and separation. Such behaviour is currently limited to a few dozen physisorbents that typically switch through a breathing mechanism requiring structural contortions. Here we show a clathrate (non-porous) coordination network that undergoes gas-induced switching between multiple non-porous phases through transient porosity, which involves the diffusion of guests between discrete voids through intra-network distortions. This material is synthesized as a clathrate phase with solvent-filled cavities; evacuation affords a single-crystal to single-crystal transformation to a phase with smaller cavities. At 298 K, carbon dioxide, acetylene, ethylene and ethane induce reversible switching between guest-free and gas-loaded clathrate phases. For carbon dioxide and acetylene at cryogenic temperatures, phases showing progressively higher loadings were observed and characterized using in situ X-ray diffraction, and the mechanism of diffusion was computationally elucidated.}, journal={NATURE CHEMISTRY}, author={Nikolayenko, Varvara I. and Castell, Dominic C. and Sensharma, Debobroto and Shivanna, Mohana and Loots, Leigh and Forrest, Katherine A. and Solanilla-Salinas, Carlos J. and Otake, Ken-ichi and Kitagawa, Susumu and Barbour, Leonard J. and et al.}, year={2023}, month={Feb} }
 @article{suepaul_forrest_georgiev_forster_lohstroh_grzimek_dunning_reynolds_humphrey_eckert_et al._2022, title={Investigating H2 Adsorption in Isostructural Metal-Organic Frameworks M-CUK-1 (M = Co and Mg) through Experimental and Theoretical Studies}, volume={2}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.1c20312}, abstractNote={A combined experimental and theoretical study of H2 adsorption was carried out in Co-CUK-1 and Mg-CUK-1, two isostructural metal-organic frameworks (MOFs) that consist of M2+ ions (M = Co and Mg) coordinated to pyridine-2,4-dicarboxylate (pdc2-) and OH- ligands. These MOFs possess saturated metal centers in distorted octahedral environments and narrow pore sizes and display high chemical and thermal stability. Previous experimental studies revealed that Co-CUK-1 exhibits a H2 uptake of 183 cm3 g-1 at 77 K/1.0 atm [ Angew. Chem., Int. Ed. 2007, 46, 272-275, DOI: 10.1002/anie.200601627], while that for Mg-CUK-1 under the same conditions is 240 cm3 g-1 on the basis of the experimental measurements carried out herein. The theoretical H2 adsorption isotherms are in close agreement with the corresponding experimental measurements for simulations using electrostatic and polarizable potentials of the adsorbate. Through simulated annealing calculations, it was found that the primary binding site for H2 in both isostructural analogues is localized proximal to the center of the aromatic rings belonging to the pdc2- linkers. Inelastic neutron scattering (INS) spectroscopic studies of H2 adsorbed in both MOFs revealed a rotational tunnelling transition occurring at around 8 meV in the corresponding spectra; this peak represents H2 adsorbed at the primary binding site. Two-dimensional quantum rotation calculations for H2 localized at the primary and secondary binding sites in both MOFs yielded rotational energy levels that are in agreement with the transitions observed in the INS spectra. Even though both M-CUK-1 analogues possess different metal ions, they exhibit similar electrostatic environments, modeled structures at H2 saturation, and rotational potentials for H2 adsorbed at the most favorable adsorption site. Overall, this study demonstrates how important molecular-level details of the H2 adsorption mechanism inside MOF micropores can be derived from a combination of experimental measurements and theoretical calculations using two stable and isostructural MOFs with saturated metal centers and small pore windows as model systems.}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Suepaul, Shanelle and Forrest, Katherine A. and Georgiev, Peter A. and Forster, Paul M. and Lohstroh, Wiebke and Grzimek, Veronika and Dunning, Samuel G. and Reynolds, Joseph E., III and Humphrey, Simon M. and Eckert, Juergen and et al.}, year={2022}, month={Feb} }
 @article{forrest_verma_ye_ren_ma_pham_space_2022, title={Methane storage in flexible and dynamical metal–organic frameworks}, url={https://doi.org/10.1063/5.0072805}, DOI={10.1063/5.0072805}, abstractNote={Recently, there has been significant interest in methane as an abundant and cleaner burning alternative to fossil fuels. Consequently, the design of media capable of the storage of methane under practical conditions has become an area of significant interest to the scientific community. While metal−organic frameworks have seen pronounced examination for this application, flexible metal−organic framework variants have been little examined despite having tremendous promise for methane storage applications. This work provides an overview of the current state of the art regarding the investigation of these systems for the purpose of providing a baseline for future research.}, journal={Chemical Physics Reviews}, author={Forrest, Katherine A. and Verma, Gaurav and Ye, Yingxiang and Ren, Junyu and Ma, Shengqian and Pham, Tony and Space, Brian}, year={2022}, month={Jun} }
 @article{niu_fan_pham_verma_forrest_space_thallapally_al-enizi_ma_2022, title={Self-Adjusting Metal-Organic Framework for Efficient Capture of Trace Xenon and Krypton}, volume={1}, ISSN={["1521-3773"]}, DOI={10.1002/anie.202117807}, abstractNote={The capture of the xenon and krypton from nuclear reprocessing off-gas is essential to the treatment of radioactive waste. Although various porous materials have been employed to capture Xe and Kr, the development of high-performance adsorbents capable of trapping Xe/Kr at very low partial pressure as in the in the nuclear reprocessing off-gas conditions remains challenging. Herein, we report a self-adjusting metal-organic framework based on multiple weak binding interactions to capture trace Xe and Kr from the nuclear reprocessing off-gas. The self-adjusting behavior of ATC-Cu and its mechanism have been visualized by the in-situ single-crystal X-ray diffraction studies and theoretical calculations. The self-adjusting behavior endows ATC-Cu unprecedented uptake capacities of 2.65 and 0.52 cm 3 g -1 for Xe and Kr respectively at 0.1 bar and 298 K, as well as the record Xe capture capability from the nuclear reprocessing off-gas. Our work not only provides a benchmark Xe adsorbent but proposes a new route to construct smart materials for efficient separations.}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Niu, Zheng and Fan, Ziwen and Pham, Tony and Verma, Gaurav and Forrest, Katherine A. and Space, Brian and Thallapally, Praveen K. and Al-Enizi, Abdullah M. and Ma, Shengqian}, year={2022}, month={Jan} }
 @article{mukherjee_kumar_bezrukov_tan_pham_forrest_oyekan_qazvini_madden_space_et al._2021, title={Amino-Functionalised Hybrid Ultramicroporous Materials that Enable Single-Step Ethylene Purification from a Ternary Mixture}, volume={60}, ISSN={["1521-3773"]}, DOI={10.1002/anie.202100240}, abstractNote={Abstract Pyrazine‐linked hybrid ultramicroporous (pore size <7 Å) materials (HUMs) offer benchmark performance for trace carbon capture thanks to strong selectivity for CO2 over small gas molecules, including light hydrocarbons. That the prototypal pyrazine‐linked HUMs are amenable to crystal engineering has enabled second generation HUMs to supersede the performance of the parent HUM, SIFSIX‐3‐Zn, mainly through substitution of the metal and/or the inorganic pillar. Herein, we report that two isostructural aminopyrazine‐linked HUMs, MFSIX‐17‐Ni (17=aminopyrazine; M=Si, Ti), which we had anticipated would offer even stronger affinity for CO2 than their pyrazine analogs, unexpectedly exhibit reduced CO2 affinity but enhanced C2H2 affinity. MFSIX‐17‐Ni are consequently the first physisorbents that enable single‐step production of polymer‐grade ethylene (>99.95 % for SIFSIX‐17‐Ni) from a ternary equimolar mixture of ethylene, acetylene and CO2 thanks to coadsorption of the latter two gases. We attribute this performance to the very different binding sites in MFSIX‐17‐Ni versus SIFSIX‐3‐Zn.}, number={19}, journal={ANGEWANDTE CHEMIE-INTERNATIONAL EDITION}, author={Mukherjee, Soumya and Kumar, Naveen and Bezrukov, Andrey A. and Tan, Kui and Pham, Tony and Forrest, Katherine A. and Oyekan, Kolade A. and Qazvini, Omid T. and Madden, David G. and Space, Brian and et al.}, year={2021}, month={May}, pages={10902–10909} }
 @article{verma_forrest_carr_vardhan_ren_pham_space_kumar_ma_2021, title={Indium-Organic Framework with soc Topology as a Versatile Catalyst for Highly Efficient One-Pot Strecker Synthesis of alpha-aminonitriles}, volume={13}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.1c09074}, abstractNote={An In(III) based metal-organic framework (MOF), In-pbpta, with soc topology was constructed from the trigonal prismatic [In3(μ3-O)(H2O)3(O2C-)6] secondary building unit (SBU) and a custom-designed tetratopic linker H4pbpta (pbpta = 4,4',4″,4‴-(1,4-phenylenbis(pyridine-4,2,6-triyl))-tetrabenzoic acid)). The obtained MOF shows a Brunauer-Emmett-Teller surface area of 1341 m2/g with a pore volume of 0.64 cm3/g, which is the highest among the scarcely reported In-soc-MOFs. The constructed MOF demonstrates excellent performance as a heterogeneous Lewis acid catalyst for highly efficient conversion in a one-pot multicomponent Strecker reaction for the preparation of α-aminonitriles under solvent-free conditions, which can be easy to separate and recycle without significant loss of activity for up to seven cycles. The computational modeling studies suggest the presence of the three substrates in close vicinity to the In-oxo cluster. The strong interactions of the aldehyde/ketone and the amine with the In-oxo cluster together with the readily available cyanide ion around the In-oxo cluster lead to high catalytic conversion within a short period of time for the MOF catalyst. Our work therefore lays a foundation to develop MOF as a new class of efficient heterogeneous catalyst for one-pot Strecker reaction.}, number={44}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Verma, Gaurav and Forrest, Katherine and Carr, Benjamin A. and Vardhan, Harsh and Ren, Junyu and Pham, Tony and Space, Brian and Kumar, Sanjay and Ma, Shengqian}, year={2021}, month={Nov}, pages={52023–52033} }
 @article{ye_xian_cui_tan_gong_liang_pham_pandey_krishna_lan_et al._2021, title={Metal-Organic Framework Based Hydrogen-Bonding Nanotrap for Efficient Acetylene Storage and Separation}, volume={12}, ISSN={["1520-5126"]}, DOI={10.1021/jacs.1c10620}, abstractNote={The removal of carbon dioxide (CO2) from acetylene (C2H2) is a critical industrial process for manufacturing high-purity C2H2. However, it remains challenging to address the tradeoff between adsorption capacity and selectivity, on account of their similar physical properties and molecular sizes. To overcome this difficulty, here we report a novel strategy involving the regulation of a hydrogen-bonding nanotrap on the pore surface to promote the separation of C2H2/CO2 mixtures in three isostructural metal-organic frameworks (MOFs, named MIL-160, CAU-10H, and CAU-23, respectively). Among them, MIL-160, which has abundant hydrogen-bonding acceptors as nanotraps, can selectively capture acetylene molecules and demonstrates an ultrahigh C2H2 storage capacity (191 cm3 g-1, or 213 cm3 cm-3) but much less CO2 uptake (90 cm3 g-1) under ambient conditions. The C2H2 adsorption amount of MIL-160 is remarkably higher than those for the other two isostructural MOFs (86 and 119 cm3 g-1 for CAU-10H and CAU-23, respectively) under the same conditions. More importantly, both simulation and experimental breakthrough results show that MIL-160 sets a new benchmark for equimolar C2H2/CO2 separation in terms of the separation potential (Δqbreak = 5.02 mol/kg) and C2H2 productivity (6.8 mol/kg). In addition, in situ FT-IR experiments and computational modeling further reveal that the unique host-guest multiple hydrogen-bonding interaction between the nanotrap and C2H2 is the key factor for achieving the extraordinary acetylene storage capacity and superior C2H2/CO2 selectivity. This work provides a novel and powerful approach to address the tradeoff of this extremely challenging gas separation.}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Ye, Yingxiang and Xian, Shikai and Cui, Hui and Tan, Kui and Gong, Lingshan and Liang, Bin and Pham, Tony and Pandey, Haardik and Krishna, Rajamani and Lan, Pui Ching and et al.}, year={2021}, month={Dec} }
 @article{cao_mukherjee_pham_wang_wang_zhang_jiang_tang_forrest_space_et al._2021, title={One-step ethylene production from a four-component gas mixture by a single physisorbent}, volume={12}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-021-26473-8}, abstractNote={One-step adsorptive purification of ethylene (C2H4) from four-component gas mixtures comprising acetylene (C2H2), ethylene (C2H4), ethane (C2H6) and carbon dioxide (CO2) is an unmet challenge in the area of commodity purification. Herein, we report that the ultramicroporous sorbent Zn-atz-oba (H2oba = 4,4-dicarboxyl diphenyl ether; Hatz = 3-amino-1,2,4-triazole) enables selective adsorption of C2H2, C2H6 and CO2 over C2H4 thanks to the binding sites that lie in its undulating pores. Molecular simulations provide insight into the binding sites in Zn-atz-oba that are responsible for coadsorption of C2H2, C2H6 and CO2 over C2H4. Dynamic breakthrough experiments demonstrate that the selective binding exhibited by Zn-atz-oba can produce polymer-grade purity (>99.95%) C2H4 from binary (1:1 for C2H4/C2H6), ternary (1:1:1 for C2H2/C2H4/C2H6) and quaternary (1:1:1:1 for C2H2/C2H4/C2H6/CO2) gas mixtures in a single step.}, number={1}, journal={NATURE COMMUNICATIONS}, author={Cao, Jian-Wei and Mukherjee, Soumya and Pham, Tony and Wang, Yu and Wang, Teng and Zhang, Tao and Jiang, Xue and Tang, Hui-Juan and Forrest, Katherine A. and Space, Brian and et al.}, year={2021}, month={Nov} }
 @article{forrest_pham_chen_jiang_madden_franz_hogan_zaworotko_space_2021, title={Tuning the Selectivity between C2H2 and CO2 in Molecular Porous Materials}, volume={37}, ISSN={["0743-7463"]}, DOI={10.1021/acs.langmuir.1c02009}, abstractNote={A combined experimental and theoretical study of C2H2 and CO2 adsorption and separation was performed in two isostructural molecular porous materials (MPMs): MPM-1-Cl ([Cu2(adenine)4Cl2]Cl2) and MPM-1-TIFSIX ([Cu2(adenine)4(TiF6)2]). It was revealed that MPM-1-Cl displayed higher low-pressure uptake, isosteric heat of adsorption (Qst), and selectivity for C2H2 than CO2, whereas the opposite was observed for MPM-1-TIFSIX. While MPM-1-Cl contains only one type of accessible channel, which has a greater preference toward C2H2, MPM-1-TIFSIX contains three distinct accessible channels, one of which is a confined region between two large channels that represents the primary binding site for both adsorbates. According to molecular simulations, the initial adsorption site in MPM-1-TIFSIX interacts more strongly with CO2 than C2H2, thus explaining the inversion of adsorbate selectivity relative to MPM-1-Cl.}, number={47}, journal={LANGMUIR}, author={Forrest, Katherine A. and Pham, Tony and Chen, Kai-Jie and Jiang, Xue and Madden, David G. and Franz, Douglas M. and Hogan, Adam and Zaworotko, Michael J. and Space, Brian}, year={2021}, month={Nov}, pages={13838–13845} }
 @article{verma_kumar_vardhan_ren_niu_pham_wojtas_butikofer_echeverria garcia_chen_et al._2020, title={A robust soc-MOF platform exhibiting high gravimetric uptake and volumetric deliverable capacity for on-board methane storage}, volume={4}, ISSN={1998-0124 1998-0000}, url={http://dx.doi.org/10.1007/s12274-020-2794-9}, DOI={10.1007/s12274-020-2794-9}, journal={Nano Research}, publisher={Springer Science and Business Media LLC}, author={Verma, Gaurav and Kumar, Sanjay and Vardhan, Harsh and Ren, Junyu and Niu, Zheng and Pham, Tony and Wojtas, Lukasz and Butikofer, Sydney and Echeverria Garcia, Jose C. and Chen, Yu-Sheng and et al.}, year={2020}, month={Apr} }
 @article{mukherjee_he_franz_wang_xian_bezrukov_space_xu_he_zaworotko_2020, title={Halogen–C 2 H 2 Binding in Ultramicroporous Metal–Organic Frameworks (MOFs) for Benchmark C 2 H 2             /CO 2 Separation Selectivity}, volume={26}, ISSN={0947-6539 1521-3765}, url={http://dx.doi.org/10.1002/chem.202000920}, DOI={10.1002/chem.202000920}, abstractNote={Breaking up is hard to do, especially for acetylene and carbon dioxide, but benchmark separation with selectivity for these gases has been accomplished in a crystal engineered family of ultramicroporous metal-organic frameworks (MOFs) thanks to acetylene binding sweet spots enabled by HCCH⋅⋅⋅halogen interactions. More information can be found in the Communication by Z. Xu, J. He, M. J. Zaworotko, et al. on page 4923.}, number={22}, journal={Chemistry – A European Journal}, publisher={Wiley}, author={Mukherjee, Soumya and He, Yonghe and Franz, Douglas and Wang, Shi‐Qiang and Xian, Wan‐Ru and Bezrukov, Andrey A. and Space, Brian and Xu, Zhengtao and He, Jun and Zaworotko, Michael J.}, year={2020}, month={Apr}, pages={4881–4881} }
 @article{mukherjee_he_franz_wang_xian_bezrukov_space_xu_he_zaworotko_2020, title={Halogen–C2H2 Binding in Ultramicroporous Metal–Organic Frameworks (MOFs) for Benchmark C2H2/CO2 Separation Selectivity}, volume={26}, DOI={10.1002/chem.202000008}, abstractNote={Acetylene (C2H2) capture is a step in a number of industrial processes but comes with a high energy footprint. Whereas physisorbents have the potential to reduce this energy footprint, they are handicapped by generally poor selectivity vs. other relevant gases such as CO2 and C2H4. In the case of CO2, the respective physicochemical properties are so similar that traditional physisorbents such as zeolites, silica and activated carbons cannot differentiate well between CO2 and C2H2. Herein we report that a family of three isostructural, ultramicroporous (< 7 Å) diamondoid metal-organic frameworks, [Cu(TMBP)X] (TMBP =  3,3',5,5'-tetramethyl-4,4'-bipyrazole), TCuX (X = Cl, Br, I), offer new benchmark C2H2/CO2 separation selectivity at ambient temperature and pressure. We attribute this performance to a new type of strong binding site for C2H2. Specifically, halogen…HC interactions coupled with other noncovalent in a tight binding site is C2H2-specific vs. CO2. The binding site is distinct from those found in previous benchmark sorbents, which are based upon open metal sites or electrostatic interactions enabled by inorganic fluoro or oxo anions.}, number={22}, journal={Chemistry—A European Journal}, author={Mukherjee, Soumya and He, Yonghe and Franz, Douglas and Wang, Shi-Qiang and Xian, Wan-Ru and Bezrukov, Andrey A. and Space, Brian and Xu, Zhengtao and He, Jun and Zaworotko, Michael J.}, year={2020}, month={Apr}, pages={4923–4929} }
 @article{mukherjee_chen_bezrukov_mostrom_terskikh_franz_wang_kumar_chen_space_et al._2020, title={Innentitelbild: Ultramicropore Engineering by Dehydration to Enable Molecular Sieving of H2 by Calcium Trimesate (Angew. Chem. 37/2020)}, url={https://doi.org/10.1002/ange.202009691}, DOI={10.1002/ange.202009691}, abstractNote={Physikalische Trennungen können chemischen Trennungen überlegen sein, das gilt insbesondere für Siebverfahren schwierig zu trennender Gasgemische. Ein ideales Sieben von industriellen Gasen erfordert jedoch eine sehr präzise, ultramikroporöse Porenfenstergröße. In ihrem Forschungsartikel auf S. 16322 beschreiben Y. Huang, M. J. Zaworotko et al. eine neue Variante von Ca-Trimesat, welche die genau richtige Porengröße (0.31 nm) für ein ideales Sieben von H2 gegenüber CO2, zweier Hauptbestandteile von Syngas, aufweist.}, journal={Angewandte Chemie}, author={Mukherjee, Soumya and Chen, Shoushun and Bezrukov, Andrey A. and Mostrom, Matthew and Terskikh, Victor V. and Franz, Douglas and Wang, Shi‐Qiang and Kumar, Amrit and Chen, Mansheng and Space, Brian and et al.}, year={2020}, month={Sep} }
 @article{mukherjee_chen_bezrukov_mostrom_terskikh_franz_wang_kumar_chen_space_et al._2020, title={Inside Cover: Ultramicropore Engineering by Dehydration to Enable Molecular Sieving of H2 by Calcium Trimesate (Angew. Chem. Int. Ed. 37/2020)}, url={https://doi.org/10.1002/anie.202009691}, DOI={10.1002/anie.202009691}, abstractNote={Physical separations can be superior to chemical separations when it comes to energetics and kinetics, especially when ideal sieving is feasible among hard-to-separate gas mixtures. Unfortunately, for industrial gases a very precise pore window size, which must be ultramicroporous, is needed for ideal sieving. In their Research Article on page 16188,Y. Huang, M. J. Zaworotko, and co-workers describe a new variant of Ca-trimesate that offers just the right pore size (0.31 nm) to enable ideal sieving of H2 from CO2, two of the primary components of syngas.}, journal={Angewandte Chemie International Edition}, author={Mukherjee, Soumya and Chen, Shoushun and Bezrukov, Andrey A. and Mostrom, Matthew and Terskikh, Victor V. and Franz, Douglas and Wang, Shi‐Qiang and Kumar, Amrit and Chen, Mansheng and Space, Brian and et al.}, year={2020}, month={Sep} }
 @inbook{pham_space_2020, title={Insights into the Gas Adsorption Mechanisms in Metal–Organic Frameworks from Classical Molecular Simulations}, ISBN={9783030473396 9783030473402}, ISSN={2367-4067 2367-4075}, url={http://dx.doi.org/10.1007/978-3-030-47340-2_7}, DOI={10.1007/978-3-030-47340-2_7}, abstractNote={Classical molecular simulations can provide significant insights into the gas adsorption mechanisms and binding sites in various metal–organic frameworks (MOFs). These simulations involve assessing the interactions between the MOF and an adsorbate molecule by calculating the potential energy of the MOF–adsorbate system using a functional form that generally includes nonbonded interaction terms, such as the repulsion/dispersion and permanent electrostatic energies. Grand canonical Monte Carlo (GCMC) is the most widely used classical method that is carried out to simulate gas adsorption and separation in MOFs and identify the favorable adsorbate binding sites. In this review, we provide an overview of the GCMC methods that are normally utilized to perform these simulations. We also describe how a typical force field is developed for the MOF, which is required to compute the classical potential energy of the system. Furthermore, we highlight some of the common analysis techniques that have been used to determine the locations of the preferential binding sites in these materials. We also review some of the early classical molecular simulation studies that have contributed to our working understanding of the gas adsorption mechanisms in MOFs. Finally, we show that the implementation of classical polarization for simulations in MOFs can be necessary for the accurate modeling of an adsorbate in these materials, particularly those that contain open-metal sites. In general, molecular simulations can provide a great complement to experimental studies by helping to rationalize the favorable MOF–adsorbate interactions and the mechanism of gas adsorption.}, booktitle={Topics in Current Chemistry Collections}, publisher={Springer International Publishing}, author={Pham, Tony and Space, Brian}, year={2020}, pages={215–279} }
 @article{pham_space_2020, title={Insights into the Gas Adsorption Mechanisms in Metal–Organic Frameworks from Classical Molecular Simulations}, volume={378}, url={https://doi.org/10.1007/s41061-019-0276-x}, DOI={10.1007/s41061-019-0276-x}, abstractNote={Classical molecular simulations can provide significant insights into the gas adsorption mechanisms and binding sites in various metal-organic frameworks (MOFs). These simulations involve assessing the interactions between the MOF and an adsorbate molecule by calculating the potential energy of the MOF-adsorbate system using a functional form that generally includes nonbonded interaction terms, such as the repulsion/dispersion and permanent electrostatic energies. Grand canonical Monte Carlo (GCMC) is the most widely used classical method that is carried out to simulate gas adsorption and separation in MOFs and identify the favorable adsorbate binding sites. In this review, we provide an overview of the GCMC methods that are normally utilized to perform these simulations. We also describe how a typical force field is developed for the MOF, which is required to compute the classical potential energy of the system. Furthermore, we highlight some of the common analysis techniques that have been used to determine the locations of the preferential binding sites in these materials. We also review some of the early classical molecular simulation studies that have contributed to our working understanding of the gas adsorption mechanisms in MOFs. Finally, we show that the implementation of classical polarization for simulations in MOFs can be necessary for the accurate modeling of an adsorbate in these materials, particularly those that contain open-metal sites. In general, molecular simulations can provide a great complement to experimental studies by helping to rationalize the favorable MOF-adsorbate interactions and the mechanism of gas adsorption.}, number={1}, journal={Topics in Current Chemistry}, publisher={Springer Science and Business Media LLC}, author={Pham, Tony and Space, Brian}, year={2020}, month={Feb} }
 @article{hogan_space_2020, title={Next-Generation Accurate, Transferable, and Polarizable Potentials for Material Simulations}, volume={16}, ISSN={1549-9618 1549-9626}, url={http://dx.doi.org/10.1021/acs.jctc.0c00837}, DOI={10.1021/acs.jctc.0c00837}, abstractNote={PHAHST (potentials with high accuracy, high speed, and transferability) intermolecular potential energy functions have been developed from first principles for H2, N2, the noble gases, and a metal-organic material, HKUST-1. The potentials are designed from the outset to be transferable to heterogeneous environments including porous materials, interfaces, and material simulations. This is accomplished by theoretically justified choices for all functional forms, parameters, and mixing rules, including explicit polarization in every environment and fitting to high quality electronic structure calculations using methods that are tractable for real systems. The models have been validated in neat systems by comparison to second virial coefficients and bulk pressure-density isotherms. For inhomogeneous applications, our main target, comparisons are presented to previously published experimental studies on the metal-organic material HKUST-1 including adsorption, isosteric heats of adsorption, binding site locations, and binding site energies. A systematic prescription is provided for developing compatible potentials for additional small molecules and materials. The resulting models are recommended for use in complex heterogeneous simulations where existing potentials may be inadequate.}, number={12}, journal={Journal of Chemical Theory and Computation}, publisher={American Chemical Society (ACS)}, author={Hogan, Adam and Space, Brian}, year={2020}, month={Nov}, pages={7632–7644} }
 @article{elsaidi_mohamed_helal_galanek_pham_suepaul_space_hopkinson_thallapally_li_2020, title={Radiation-resistant metal-organic framework enables efficient separation of krypton fission gas from spent nuclear fuel}, volume={11}, ISSN={2041-1723}, url={http://dx.doi.org/10.1038/s41467-020-16647-1}, DOI={10.1038/s41467-020-16647-1}, abstractNote={Abstract Capture and storage of volatile radionuclides that result from processing of used nuclear fuel is a major challenge. Solid adsorbents, in particular ultra-microporous metal-organic frameworks, could be effective in capturing these volatile radionuclides, including 85 Kr. However, metal-organic frameworks are found to have higher affinity for xenon than for krypton, and have comparable affinity for Kr and N 2 . Also, the adsorbent needs to have high radiation stability. To address these challenges, here we evaluate a series of ultra-microporous metal-organic frameworks, SIFSIX-3-M (M = Zn, Cu, Ni, Co, or Fe) for their capability in 85 Kr separation and storage using a two-bed breakthrough method. These materials were found to have higher Kr/N 2 selectivity than current benchmark materials, which leads to a notable decrease in the nuclear waste volume. The materials were systematically studied for gamma and beta irradiation stability, and SIFSIX-3-Cu is found to be the most radiation resistant.}, number={1}, journal={Nature Communications}, publisher={Springer Science and Business Media LLC}, author={Elsaidi, Sameh K. and Mohamed, Mona H. and Helal, Ahmed S. and Galanek, Mitchell and Pham, Tony and Suepaul, Shanelle and Space, Brian and Hopkinson, David and Thallapally, Praveen K. and Li, Ju}, year={2020}, month={Jun} }
 @article{suepaul_forrest_pham_space_2020, title={Simulations of H2 Sorption in an Anthracene-Functionalized rht-Metal–Organic Framework}, volume={124}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/acs.jpcc.0c02791}, DOI={10.1021/acs.jpcc.0c02791}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations were performed to investigate H2 sorption in the rht-metal–organic framework (MOF) MFM-132, which is composed of two chemically distinct Cu2+ ions coo...}, number={25}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Suepaul, Shanelle and Forrest, Katherine A. and Pham, Tony and Space, Brian}, year={2020}, month={May}, pages={13753–13764} }
 @article{mukherjee_chen_bezrukov_mostrom_terskikh_franz_wang_kumar_chen_space_et al._2020, title={Ultramicropore Engineering by Dehydration to Enable Molecular Sieving of H2 by Calcium Trimesate}, url={https://doi.org/10.1002/anie.202006414}, DOI={10.1002/anie.202006414}, abstractNote={The high energy footprint of commodity gas purification and ever-increasing demand for gases require new approaches to gas separation. Kinetic separation of gas mixtures through molecular sieving can enable "ideal" separation through molecular size or shape exclusion. Physisorbents must exhibit just the right pore diameter to enable such ideal separation, but the 0.3-0.4 nm range relevant to small gas molecules is hard to control with precision. Herein, we report that dehydration of the ultramicroporous metal-organic framework Ca-trimesate, Ca(HBTC) . H2O (H3BTC = trimesic acid), bnn-1-Ca-H2O, affords a narrow pore variant, Ca(HBTC), bnn-1-Ca. Whereas bnn-1-Ca-H2O (pore diameter 0.34 nm) exhibits ultra-high CO2/N2, CO2/CH4 and C2H2/C2H4 binary selectivities, bnn-1-Ca (pore diameter 0.31 nm) offers ideal selectivities for H 2 /CO 2 and H2/N2 under cryogenic conditions. Ca-trimesate, the first physisorbent to exhibit H2 sieving under cryogenic conditions, could be prototypal for a potentially general approach to exert precise control over pore diameter in physisorbents.}, journal={Angewandte Chemie International Edition}, author={Mukherjee, Soumya and Chen, Shoushun and Bezrukov, Andrey A. and Mostrom, Matthew and Terskikh, Victor V. and Franz, Douglas and Wang, Shi‐Qiang and Kumar, Amrit and Chen, Mansheng and Space, Brian and et al.}, year={2020}, month={Sep} }
 @article{mukherjee_chen_bezrukov_mostrom_terskikh_franz_wang_kumar_chen_space_et al._2020, title={Ultramicropore Engineering by Dehydration to Enable Molecular Sieving of H2 by Calcium Trimesate}, url={https://doi.org/10.1002/ange.202006414}, DOI={10.1002/ange.202006414}, abstractNote={Abstract The high energy footprint of commodity gas purification and increasing demand for gases require new approaches to gas separation. Kinetic separation of gas mixtures through molecular sieving can enable separation by molecular size or shape exclusion. Physisorbents must exhibit the right pore diameter to enable separation, but the 0.3–0.4 nm range relevant to small gas molecules is hard to control. Herein, dehydration of the ultramicroporous metal–organic framework Ca‐trimesate, Ca(HBTC)⋅H 2 O (H 3 BTC=trimesic acid), bnn‐1‐Ca‐H 2 O, affords a narrow pore variant, Ca(HBTC), bnn‐1‐Ca. Whereas bnn‐1‐Ca‐H 2 O (pore diameter 0.34 nm) exhibits ultra‐high CO 2 /N 2 , CO 2 /CH 4 , and C 2 H 2 /C 2 H 4 binary selectivity, bnn‐1‐Ca (pore diameter 0.31 nm) offers ideal selectivity for H 2 /CO 2 and H 2 /N 2 under cryogenic conditions. Ca‐trimesate, the first physisorbent to exhibit H 2 sieving under cryogenic conditions, could be a prototype for a general approach to exert precise control over pore diameter in physisorbents.}, journal={Angewandte Chemie}, author={Mukherjee, Soumya and Chen, Shoushun and Bezrukov, Andrey A. and Mostrom, Matthew and Terskikh, Victor V. and Franz, Douglas and Wang, Shi‐Qiang and Kumar, Amrit and Chen, Mansheng and Space, Brian and et al.}, year={2020}, month={Sep} }
 @article{niu_cui_pham_lan_xing_forrest_wojtas_space_ma_2019, title={A Metal–Organic Framework Based Methane Nano‐trap for the Capture of Coal‐Mine Methane}, volume={58}, ISSN={1433-7851 1521-3773}, url={http://dx.doi.org/10.1002/anie.201904507}, DOI={10.1002/anie.201904507}, abstractNote={As a major greenhouse gas, methane, which is directly vented from the coal-mine to the atmosphere, has not yet drawn sufficient attention. To address this problem, we report a methane nano-trap that features oppositely adjacent open metal sites and dense alkyl groups in a metal-organic framework (MOF). The alkyl MOF-based methane nano-trap exhibits a record-high methane uptake and CH4 /N2 selectivity at 298 K and 1 bar. The methane molecules trapped within the alkyl MOF were crystalographically identified by single-crystal X-ray diffraction experiments, which in combination with molecular simulation studies unveiled the methane adsorption mechanism within the MOF-based nano-trap. The IAST calculations and the breakthrough experiments revealed that the alkyl MOF-based methane nano-trap is a new benchmark for CH4 /N2 separation, thereby providing a new perspective for capturing methane from coal-mine methane to recover fuel and reduce greenhouse gas emissions.}, number={30}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Niu, Zheng and Cui, Xili and Pham, Tony and Lan, Pui Ching and Xing, Huabin and Forrest, Katherine A. and Wojtas, Lukasz and Space, Brian and Ma, Shengqian}, year={2019}, month={Jul}, pages={10138–10141} }
 @article{pal_chand_madden_franz_ritter_johnson_space_curtin_das_2019, title={A Microporous Co-MOF for Highly Selective CO2 Sorption in High Loadings Involving Aryl C–H···O═C═O Interactions: Combined Simulation and Breakthrough Studies}, volume={58}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/acs.inorgchem.9b01402}, DOI={10.1021/acs.inorgchem.9b01402}, abstractNote={In the context of porous crystalline materials toward CO2 separation and capture, a new 2-fold interpenetrated 3D microporous Co-MOF, IITKGP-11 (IITKGP denotes Indian Institute of Technology Kharagpur), has been synthesized consisting of a 1D channel of ∼3.6 × 5.0 Å2 along the [101] direction with a cavity volume of 35.20%. This microporous framework with a BET surface area of 253 m2g-1 shows higher uptake of CO2 (under 1 bar, 3.35 and 2.70 mmol g-1 at 273 and 295 K, respectively), with high separation selectivities for CO2/N2 and CO2/CH4 gas mixtures under ambient conditions as estimated through IAST calculation. Moreover, real time dynamic breakthrough studies reveal the high adsorption selectivity toward CO2 for these binary mixed gases at 295 K and 1 bar. Besides high gas separation selectivity, capacity considerations in mixed gas phases are also important to check the performance of a given adsorbent. CO2 loading amounts in mixed gas phases are quite high as predicted through IAST calculation and experimentally determined from dynamic breakthrough studies. In order to get insight into the phenomena, GCMC simulation was performed demonstrating that the CO2 molecules are electrostatically trapped via interactions between oxygen on CO2 and hydrogen on pyridyl moieties of the spacers.}, number={17}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Pal, Arun and Chand, Santanu and Madden, David G. and Franz, Douglas and Ritter, Logan and Johnson, Alexis and Space, Brian and Curtin, Teresa and Das, Madhab C.}, year={2019}, month={Aug}, pages={11553–11560} }
 @article{yu_space_franz_zhou_he_li_krishna_chang_li_hu_et al._2019, title={Enhanced Gas Uptake in a Microporous Metal–Organic Framework via a Sorbate Induced-Fit Mechanism}, volume={141}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/jacs.9b07807}, DOI={10.1021/jacs.9b07807}, abstractNote={Physical adsorption of gas molecules in microporous materials is an exothermic process, with desorption entropy driving a decrease in uptake with temperature. Enhanced gas sorption with increasing temperature is rare in porous materials and is indicative sorbate initiated structural change. Here, sorption of C2H6, C3H6 and C3H8 in a flexible microporous MOF {Cu(FPBDC)]·DMF}n (NKU-FlexMOF-1) (H2FPBDC = 5-(5-fluoropyridin-3-yl)-1,3-benzenedicarboxylic acid), that increases with rising temperature over a practically useful temperature and pressure range, is reported along with other small molecule and hydrocarbon sorption isotherms. Single X-ray diffraction studies, temperature-dependent gas sorption isotherms, in situ and variable temperature powder X-ray diffraction experiments, and electronic structure calculations were performed to characterize the conformation-dependent sorption behavior in NKU-FlexMOF-1. In total, the data supports that the atypical sorption behavior is a result of loading-dependent structural changes in the flexible framework of NKU-FlexMOF-1 induced by sorbate specific guest-framework interactions. The sorbates cause subtle adaptations of the framework distinct to each sorbate providing an induced-fit separation mechanism to resolve chemically similar hydrocarbons through highly specific sorbate-sorbent interactions. The relevant intermolecular contacts are shown to be predominantly repulsion / dispersion interactions. NKU-FlexMOF-1 is also found to be stable in aqueous solution including toleration of pH changes. These experiments demonstrate the potential of this flexible microporous MOF for cost and energy efficient industrial hydrocarbon separation and purification processes. The efficacy for the separation of C3H6/C3H8 mixtures is explicitly demonstrated using NKU-FlexMOF-1a (i.e. activated NKU-FlexMOF-1) for a particular useful temperature range.}, number={44}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Yu, Mei-Hui and Space, Brian and Franz, Douglas and Zhou, Wei and He, Chaohui and Li, Libo and Krishna, Rajamani and Chang, Ze and Li, Wei and Hu, Tong-Liang and et al.}, year={2019}, month={Oct}, pages={17703–17712} }
 @article{madden_o’nolan_chen_hua_kumar_pham_forrest_space_perry_khraisheh_et al._2019, title={Highly selective CO2 removal for one-step liquefied natural gas processing by physisorbents}, volume={55}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c9cc00626e}, DOI={10.1039/c9cc00626e}, abstractNote={Industrial specifications require CO2 concentrations in natural gas below 50 ppm during liquefaction because of corrosion and CO2 freezing. Herein, we report a physisorbent (TIFSIX-3-Ni) that exhibits new benchmark CO2/CH4 selectivity and fast kinetics, thereby enabling one-step LNG processing to CO2 levels of 25 ppm.}, number={22}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Madden, David G. and O’Nolan, Daniel and Chen, Kai-Jie and Hua, Carol and Kumar, Amrit and Pham, Tony and Forrest, Katherine A. and Space, Brian and Perry, John J. and Khraisheh, Majeda and et al.}, year={2019}, pages={3219–3222} }
 @article{forrest_pham_elsaidi_mohamed_thallapally_zaworotko_space_2019, title={Investigating CO2 Sorption in SIFSIX-3-M (M = Fe, Co, Ni, Cu, Zn) through Computational Studies}, volume={19}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/acs.cgd.9b00086}, DOI={10.1021/acs.cgd.9b00086}, abstractNote={A combined Monte Carlo (MC) simulation and periodic density functional theory (DFT) study of CO2 sorption was performed in SIFSIX-3-M (M = Fe, Co, Ni, Cu, Zn), a family of hybrid ultramicroporous materials (HUMs) that consist of M2+ ions coordinated to pyrazine ligands and are pillared with SiF62– (“SIFSIX”) anions. Grand canonical Monte Carlo (GCMC) simulations of CO2 sorption in all five SIFSIX-3-M variants produced isotherms that are in good agreement with the corresponding experimental measurements. The theoretical isosteric heats of adsorption (Qst) for CO2 as obtained through canonical Monte Carlo (CMC) simulations are also in close agreement with the experimental values. Consistent with experiment, the simulations generated the following trend in the CO2 Qst: SIFSIX-3-Cu > SIFSIX-3-Ni > SIFSIX-3-Co > SIFSIX-Zn > SIFSIX-3-Fe. The magnitudes of the theoretical Qst and relative trend were further supported by periodic DFT calculations of the adsorption energy for CO2 within the respective HUMs. We att...}, number={7}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Forrest, Katherine A. and Pham, Tony and Elsaidi, Sameh K. and Mohamed, Mona H. and Thallapally, Praveen K. and Zaworotko, Michael J. and Space, Brian}, year={2019}, month={May}, pages={3732–3743} }
 @article{franz_belof_mclaughlin_cioce_tudor_hogan_laratelli_mulcair_mostrom_navas_et al._2019, title={MPMC and MCMD: Free High‐Performance Simulation Software for Atomistic Systems}, volume={2}, ISSN={2513-0390 2513-0390}, url={http://dx.doi.org/10.1002/adts.201900113}, DOI={10.1002/adts.201900113}, abstractNote={Advancements in parallel computing and hardware have allowed computational exploration of chemical systems of interest with unprecendented accuracy and efficiency. The typical development of molecular simulation software is initially inspired by a particular scientific inquiry. The softwares presented herein, MPMC (Massively Parallel Monte Carlo) and MCMD (Monte Carlo/Molecular Dynamics) were born out of a pursuit to simulate condensed phase physical and chemical interactions in porous materials. MPMC first began in 2005 and has been used for dozens of published results in the literature but has not yet been introduced in a standalone paper. MCMD is a more recent expansion and re‐write with some published work, focused on adding molecular dynamics algorithms for transport and other time‐dependent properties of chemical systems. Each software functions as a standalone with some unique and other overlapping features. A driving aim of this work is to consider periodic, long‐range polarization effects in classical simulation, and both codes are optimized to perform such calculations. Sample results will be presented which highlight methodically that inclusion of explicit polarization produces simulation results with predictive power which in general are in greater agreement with experiment than non‐polarizable analogous simulations.}, number={11}, journal={Advanced Theory and Simulations}, publisher={Wiley}, author={Franz, Douglas M. and Belof, Jonathan L. and McLaughlin, Keith and Cioce, Christian R. and Tudor, Brant and Hogan, Adam and Laratelli, Luciano and Mulcair, Meagan and Mostrom, Matthew and Navas, Alejandro and et al.}, year={2019}, month={Aug}, pages={1900113} }
 @article{han_pham_zhuo_forrest_suepaul_space_zaworotko_shi_chen_cheng_et al._2019, title={Molecular Sieving and Direct Visualization of CO2 in Binding Pockets of an Ultramicroporous Lanthanide Metal–Organic Framework Platform}, volume={11}, ISSN={1944-8244 1944-8252}, url={http://dx.doi.org/10.1021/acsami.9b04619}, DOI={10.1021/acsami.9b04619}, abstractNote={Inspired by the structure of carbonic anhydrase, we developed a robust ultramicroporous lanthanide metal-organic framework (MOF) platform (NKMOF-3-Ln), which possess enzyme-like porous pocket to selectively bind with CO2 at ambient condition. Notably, CO2 molecules can be precisely observed in the single crystal structure of NKMOF-3-Ln. Highly ordered CO2 molecules can strongly interact with framework via electrostatic interaction of nitrates. We found that the CO2 adsorption capacity and binding energy were gradually enhanced as lanthanide contracting. The strong CO2 binding affinity endows NKMOF-3-Ln excellent CO2 separation performance, verified by experimental breakthrough results. Moreover, ascribed to the specific binding affinity of CO2, NKMOF-3-Eu showed fluorescence response to CO2.}, number={26}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Han, Lin and Pham, Tony and Zhuo, Mingjing and Forrest, Katherine A. and Suepaul, Shanelle and Space, Brian and Zaworotko, Michael J. and Shi, Wei and Chen, Yao and Cheng, Peng and et al.}, year={2019}, month={Jun}, pages={23192–23197} }
 @article{peng_he_pham_wang_li_krishna_forrest_hogan_suepaul_space_et al._2019, title={Robust Microporous Metal–Organic Frameworks for Highly Efficient and Simultaneous Removal of Propyne and Propadiene from Propylene}, volume={58}, ISSN={1433-7851 1521-3773}, url={http://dx.doi.org/10.1002/anie.201904312}, DOI={10.1002/anie.201904312}, abstractNote={Simultaneous removal of trace amounts of propyne and propadiene from propylene is an important but challenging industrial process. We report herein a class of microporous metal-organic frameworks (NKMOF-1-M) with exceptional water stability and remarkably high uptakes for both propyne and propadiene at low pressures. NKMOF-1-M separated a ternary propyne/propadiene/propylene (0.5 : 0.5 : 99.0) mixture with the highest reported selectivity for the production of polymer-grade propylene (99.996 %) at ambient temperature, as attributed to its strong binding affinity for propyne and propadiene over propylene. Moreover, we were able to visualize propyne and propadiene molecules in the single-crystal structure of NKMOF-1-M through a convenient approach under ambient conditions, which helped to precisely understand the binding sites and affinity for propyne and propadiene. These results provide important guidance on using ultramicroporous MOFs as physisorbent materials.}, number={30}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Peng, Yun‐Lei and He, Chaohui and Pham, Tony and Wang, Ting and Li, Pengfei and Krishna, Rajamani and Forrest, Katherine A. and Hogan, Adam and Suepaul, Shanelle and Space, Brian and et al.}, year={2019}, month={Jul}, pages={10209–10214} }
 @article{chen_madden_mukherjee_pham_forrest_kumar_space_kong_zhang_zaworotko_2019, title={Synergistic sorbent separation for one-step ethylene purification from a four-component mixture}, volume={366}, ISSN={0036-8075 1095-9203}, url={http://dx.doi.org/10.1126/science.aax8666}, DOI={10.1126/science.aax8666}, abstractNote={Selecting for ethylene Purification of ethylene from other gases produced during its synthesis, such as acetylene, ethane, and carbon dioxide, is an energy-intensive process. Chen et al. use a mixture of microporous metal-organic framework physisorbents that are selective for one of these four gases. A series of sorbents in a packed-bed geometry produced ethylene pure enough for making polymers. Science, this issue p. 241 A packed bed filled with a series of physisorbents with different selectivities separates ethylene from three other gases. Purification of ethylene (C2H4), the largest-volume product of the chemical industry, currently involves energy-intensive processes such as chemisorption (CO2 removal), catalytic hydrogenation (C2H2 conversion), and cryogenic distillation (C2H6 separation). Although advanced physisorbent or membrane separation could lower the energy input, one-step removal of multiple impurities, especially trace impurities, has not been feasible. We introduce a synergistic sorbent separation method for the one-step production of polymer-grade C2H4 from ternary (C2H2/C2H6/C2H4) or quaternary (CO2/C2H2/C2H6/C2H4) gas mixtures with a series of physisorbents in a packed-bed geometry. We synthesized ultraselective microporous metal-organic materials that were readily regenerated, including one that was selective for C2H6 over CO2, C2H2, and C2H4.}, number={6462}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Chen, Kai-Jie and Madden, David G. and Mukherjee, Soumya and Pham, Tony and Forrest, Katherine A. and Kumar, Amrit and Space, Brian and Kong, Jie and Zhang, Qiu-Yu and Zaworotko, Michael J.}, year={2019}, month={Oct}, pages={241–246} }
 @article{mukherjee_sikdar_o’nolan_franz_gascón_kumar_kumar_scott_madden_kruger_et al._2019, title={Trace CO2 capture by an ultramicroporous physisorbent with low water affinity}, volume={5}, ISSN={2375-2548}, url={http://dx.doi.org/10.1126/sciadv.aax9171}, DOI={10.1126/sciadv.aax9171}, abstractNote={The first sorbent with high CO2 selectivity and poor water affinity addresses need for trace CO2 remediation in confined spaces. CO2 accumulation in confined spaces represents an increasing environmental and health problem. Trace CO2 capture remains an unmet challenge because human health risks can occur at 1000 parts per million (ppm), a level that challenges current generations of chemisorbents (high energy footprint and slow kinetics) and physisorbents (poor selectivity for CO2, especially versus water vapor, and/or poor hydrolytic stability). Here, dynamic breakthrough gas experiments conducted upon the ultramicroporous material SIFSIX-18-Ni-β reveal trace (1000 to 10,000 ppm) CO2 removal from humid air. We attribute the performance of SIFSIX-18-Ni-β to two factors that are usually mutually exclusive: a new type of strong CO2 binding site and hydrophobicity similar to ZIF-8. SIFSIX-18-Ni-β also offers fast sorption kinetics to enable selective capture of CO2 over both N2 (SCN) and H2O (SCW), making it prototypal for a previously unknown class of physisorbents that exhibit effective trace CO2 capture under both dry and humid conditions.}, number={11}, journal={Science Advances}, publisher={American Association for the Advancement of Science (AAAS)}, author={Mukherjee, Soumya and Sikdar, Nivedita and O’Nolan, Daniel and Franz, Douglas M. and Gascón, Victoria and Kumar, Amrit and Kumar, Naveen and Scott, Hayley S. and Madden, David G. and Kruger, Paul E. and et al.}, year={2019}, month={Nov}, pages={eaax9171} }
 @article{he_sun_gao_perman_sun_zhu_aguila_forrest_space_ma_2018, title={A Stable Metal-Organic Framework Featuring a Local Buffer Environment for Carbon Dioxide Fixation}, volume={57}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201801122}, DOI={10.1002/anie.201801122}, abstractNote={A majority of metal-organic frameworks (MOFs) fail to preserve their physical and chemical properties after exposure to acidic, neutral, or alkaline aqueous solutions, therefore limiting their practical applications in many areas. The strategy demonstrated herein is the design and synthesis of an organic ligand that behaves as a buffer to drastically boost the aqueous stability of a porous MOF (JUC-1000), which maintains its structural integrity at low and high pH values. The local buffer environment resulting from the weak acid-base pairs of the custom-designed organic ligand also greatly facilitates the performance of JUC-1000 in the chemical fixation of carbon dioxide under ambient conditions, outperforming a series of benchmark catalysts.}, number={17}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={He, Hongming and Sun, Qi and Gao, Wenyang and Perman, Jason A. and Sun, Fuxing and Zhu, Guangshan and Aguila, Briana and Forrest, Katherine and Space, Brian and Ma, Shengqian}, year={2018}, month={Mar}, pages={4657–4662} }
 @article{chen_yang_sen_madden_kumar_pham_forrest_hosono_space_kitagawa_et al._2018, title={Efficient CO2 Removal for Ultra-Pure CO Production by Two Hybrid Ultramicroporous Materials}, volume={57}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201706090}, DOI={10.1002/anie.201706090}, abstractNote={Removal of CO2 from CO gas mixtures is a necessary but challenging step during production of ultra-pure CO as processed from either steam reforming of hydrocarbons or CO2 reduction. Herein, two hybrid ultramicroporous materials (HUMs), SIFSIX-3-Ni and TIFSIX-2-Cu-i, which are known to exhibit strong affinity for CO2 , were examined with respect to their performance for this separation. The single-gas CO sorption isotherms of these HUMs were measured for the first time and are indicative of weak affinity for CO and benchmark CO2 /CO selectivity (>4000 for SIFSIX-3-Ni). This prompted us to conduct dynamic breakthrough experiments and compare performance with other porous materials. Ultra-pure CO (99.99 %) was thereby obtained from CO gas mixtures containing both trace (1 %) and bulk (50 %) levels of CO2 in a one-step physisorption-based separation process.}, number={13}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Chen, Kai-Jie and Yang, Qing-Yuan and Sen, Susan and Madden, David G. and Kumar, Amrit and Pham, Tony and Forrest, Katherine A. and Hosono, Nobuhiko and Space, Brian and Kitagawa, Susumu and et al.}, year={2018}, month={Feb}, pages={3332–3336} }
 @article{chen_yang_sen_madden_kumar_pham_forrest_hosono_space_kitagawa_et al._2018, title={Efficient CO2 Removal for Ultra‐Pure CO Production by Two Hybrid Ultramicroporous Materials}, url={https://doi.org/10.1002/ange.201706090}, DOI={10.1002/ange.201706090}, abstractNote={Abstract Removal of CO 2 from CO gas mixtures is a necessary but challenging step during production of ultra‐pure CO as processed from either steam reforming of hydrocarbons or CO 2 reduction. Herein, two hybrid ultramicroporous materials (HUMs), SIFSIX‐3‐Ni and TIFSIX‐2‐Cu‐i , which are known to exhibit strong affinity for CO 2 , were examined with respect to their performance for this separation. The single‐gas CO sorption isotherms of these HUMs were measured for the first time and are indicative of weak affinity for CO and benchmark CO 2 /CO selectivity (>4000 for SIFSIX‐3‐Ni ). This prompted us to conduct dynamic breakthrough experiments and compare performance with other porous materials. Ultra‐pure CO (99.99 %) was thereby obtained from CO gas mixtures containing both trace (1 %) and bulk (50 %) levels of CO 2 in a one‐step physisorption‐based separation process.}, journal={Angewandte Chemie}, author={Chen, Kai‐Jie and Yang, Qing‐Yuan and Sen, Susan and Madden, David G. and Kumar, Amrit and Pham, Tony and Forrest, Katherine A. and Hosono, Nobuhiko and Space, Brian and Kitagawa, Susumu and et al.}, year={2018}, month={Mar} }
 @article{pham_forrest_furukawa_eckert_space_2018, title={Hydrogen Adsorption in a Zeolitic Imidazolate Framework with lta Topology}, volume={122}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/acs.jpcc.8b04027}, DOI={10.1021/acs.jpcc.8b04027}, abstractNote={The adsorption of H2 in ZIF-76, a zeolitic imidazolate framework (ZIF) with lta topology, was investigated in a combined experimental and theoretical study. Each Zn2+ ion in the structure of this ZIF is coordinated to imidazolate and 5-chlorobenzimidazolate linkers in a 3:1 ratio. The X-ray crystal structure of ZIF-76 contains a large amount of structural disorder, which makes this a challenging material for modeling. We therefore chose to parametrize and simulate H2 adsorption in two distinct crystal structure configurations of ZIF-76 that differ by only the relative positions of one imidazolate and one 5-chlorobenzimidazolate linker. The simulated H2 adsorption isotherms for both structures are in satisfactory agreement with the newly reported experimental data for the ZIF, especially at low pressures. The experimental initial isosteric heat of adsorption (Qst) value for H2 in ZIF-76 was determined to be 7.7 kJ mol–1, which is comparable to that for other ZIFs and is fairly high for a material that does...}, number={27}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Furukawa, Hiroyasu and Eckert, Juergen and Space, Brian}, year={2018}, month={Jun}, pages={15435–15445} }
 @article{o’nolan_madden_kumar_chen_pham_forrest_patyk-kazmierczak_yang_murray_tang_et al._2018, title={Impact of partial interpenetration in a hybrid ultramicroporous material on C2H2/C2H4 separation performance}, volume={54}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c8cc01627e}, DOI={10.1039/c8cc01627e}, abstractNote={Phases of a 2-fold pcu hybrid ultramicroporous material (HUM), SIFSIX-14-Cu-i, exhibiting 99%, 93%, 89%, and 70% partial interpenetration have been obtained. 1 : 99 C2H2/C2H4 gas separation studies reveal that as the proportion of interpenetrated component decreases, so does the separation performance.}, number={28}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={O’Nolan, Daniel and Madden, David G. and Kumar, Amrit and Chen, Kai-Jie and Pham, Tony and Forrest, Katherine A. and Patyk-Kazmierczak, Ewa and Yang, Qing-Yuan and Murray, Claire A. and Tang, Chiu C. and et al.}, year={2018}, pages={3488–3491} }
 @article{forrest_franz_pham_space_2018, title={Investigating C2H2 Sorption in α-[M3(O2CH)6] (M = Mg, Mn) Through Theoretical Studies}, volume={18}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/acs.cgd.8b00770}, DOI={10.1021/acs.cgd.8b00770}, abstractNote={Simulations of C2H2 sorption were performed in α-[Mg3(O2CH)6] and α-[Mn3(O2CH)6], two isostructural metal–organic frameworks (MOFs) that consist of a network of M2+ ions coordinated to formate linkers. Previous experimental studies revealed that both MOFs display high low-pressure uptake and isosteric heat of adsorption (Qst) for C2H2 [Samsonenko, D. G. et al. Chem. Asian J. 2007, 2, 484−488]. Simulations using two recently developed potential energy functions for the sorbate in both MOFs yielded sorption isotherms and Qst values that are in reasonable agreement with the corresponding experimental measurements. Electronic structure calculations revealed that the metal ions are more positively charged in α-[Mg3(O2CH)6] than in α-[Mn3(O2CH)6], which in turn led to greater partial negative charges on the linker O atoms in the Mg variant. This resulted in the former displaying a higher calculated C2H2 uptake than the latter for all state points considered, which is consistent with what was observed experiment...}, number={9}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Forrest, Katherine A. and Franz, Douglas M. and Pham, Tony and Space, Brian}, year={2018}, month={Aug}, pages={5342–5352} }
 @article{shivanna_yang_bajpai_sen_hosono_kusaka_pham_forrest_space_kitagawa_et al._2018, title={Readily accessible shape-memory effect in a porous interpenetrated coordination network}, volume={4}, ISSN={2375-2548}, url={http://dx.doi.org/10.1126/sciadv.aaq1636}, DOI={10.1126/sciadv.aaq1636}, abstractNote={An interpenetrated flexible metal-organic material exhibits only the second example of a shape-memory effect in a porous material. Shape-memory effects are quite well-studied in general, but there is only one reported example in the context of porous materials. We report the second example of a porous coordination network that exhibits a sorbate-induced shape-memory effect and the first in which multiple sorbates, N2, CO2 and CO promote this effect. The material, a new threefold interpenetrated pcu network, [Zn2(4,4′-biphenyldicarboxylate)2(1,4-bis(4-pyridyl)benzene)]n (X-pcu-3-Zn-3i), exhibits three distinct phases: the as-synthesized α phase; a denser-activated β phase; and a shape-memory γ phase, which is intermediate in density between the α and β phases. The γ phase is kinetically stable over multiple adsorption/desorption cycles and only reverts to the β phase when heated at >400 K under vacuum. The α phase can be regenerated by soaking the γ phase in N,N′-dimethylformamide. Single-crystal x-ray crystallography studies of all three phases provide insight into the shape-memory phenomenon by revealing the nature of interactions between interpenetrated networks. The β and γ phases were further investigated by in situ coincidence powder x-ray diffraction, and their sorption isotherms were replicated by density functional theory calculations. Analysis of the structural information concerning the three phases of X-pcu-3-Zn-3i enabled us to understand structure-function relationships and propose crystal engineering principles for the design of more examples of shape-memory porous materials.}, number={4}, journal={Science Advances}, publisher={American Association for the Advancement of Science (AAAS)}, author={Shivanna, Mohana and Yang, Qing-Yuan and Bajpai, Alankriti and Sen, Susan and Hosono, Nobuhiko and Kusaka, Shinpei and Pham, Tony and Forrest, Katherine A. and Space, Brian and Kitagawa, Susumu and et al.}, year={2018}, month={Apr}, pages={eaaq1636} }
 @article{peng_pham_li_wang_chen_chen_forrest_space_cheng_zaworotko_et al._2018, title={Robust Ultramicroporous Metal-Organic Frameworks with Benchmark Affinity for Acetylene}, volume={57}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201806732}, DOI={10.1002/anie.201806732}, abstractNote={Highly selective separation and/or purification of acetylene from various gas mixtures is a relevant and difficult challenge that currently requires costly and energy-intensive chemisorption processes. Two ultramicroporous metal-organic framework physisorbents, NKMOF-1-M (M=Cu or Ni), offer high hydrolytic stability and benchmark selectivity towards acetylene versus several gases at ambient temperature. The performance of NKMOF-1-M is attributed to their exceptional acetylene binding affinity as revealed by modelling and several experimental studies: in situ single-crystal X-ray diffraction, FTIR, and gas mixture breakthrough tests. NKMOF-1-M exhibit better low-pressure uptake than existing physisorbents and possesses the highest selectivities yet reported for C2 H2 /CO2 and C2 H2 /CH4 . The performance of NKMOF-1-M is not driven by the same mechanism as current benchmark physisorbents that rely on pore walls lined by inorganic anions.}, number={34}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Peng, Yun-Lei and Pham, Tony and Li, Pengfei and Wang, Ting and Chen, Yao and Chen, Kai-Jie and Forrest, Katherine A. and Space, Brian and Cheng, Peng and Zaworotko, Michael J. and et al.}, year={2018}, month={Jul}, pages={10971–10975} }
 @article{franz_dyott_forrest_hogan_pham_space_2018, title={Simulations of hydrogen, carbon dioxide, and small hydrocarbon sorption in a nitrogen-rich rht-metal–organic framework}, volume={20}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/c7cp06885a}, DOI={10.1039/c7cp06885a}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations of gas sorption were performed in Cu-TDPAH, also known as rht-MOF-9, hereafter [1], a metal-organic framework (MOF) with rht topology consisting of Cu2+ ions coordinated to 2,5,8-tris(3,5-dicarboxyphenylamino)-1,3,4,6,7,9,9b-heptaazaphenalene (TDPAH) ligands. This MOF is notable for the presence of open-metal copper sites and high nitrogen content on the linkers. [1] Exhibits one of the highest experimental H2 uptakes at 77 K/1 atm within the extant rht-MOF family (ca. 2.72 wt%) and also has strong affinity for CO2 (5.83 mmol g-1 at 298 K/1 atm). Our simulations, which include explicit many-body polarization interactions, accurately modeled macroscopic thermodynamic properties (e.g., sorption isotherms and isosteric heats of adsorption (Qst)) as well as the binding sites for H2, CO2, CH4, C2H2, C2H4, and C2H6 in the MOF. Four different binding sites were observed through analysis of the radial distribution function (g(r)) about the two chemically distinct Cu2+ ions, simulated annealing calculations, and examination of the three-dimensional histogram showing the sites of occupancy: (1) at the Cu2+ ion facing toward the center of the linker (CuL), (2) at the Cu2+ ion facing away from the center of linker (CuC), (3) nestled between three [Cu2(O2CR)4] units in the corner of the truncated tetrahedral (T-Td) cage and (4) straddling the copper nuclei parallel to the axis of the Cu-Cu bond within the T-Td cage. The low-loading (initial) binding site in the MOF is highly sensitive to the partial charges of the Cu2+ ions that were used for parametrization. It was discovered that most sorbates prefer to sorb onto or near the Cu2+ ions that exhibit the greater partial positive charge (i.e., at site 1). The simulated H2 and CO2 sorption results obtained using a polarizable potential for the respective sorbates are in good agreement with the corresponding experimental data, especially near ambient pressure. Simulations of gas sorption were also performed in [1] using nonpolarizable potentials for the individual sorbates; these include potentials from the TraPPE force field for most sorbates.}, number={3}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Franz, Douglas M. and Dyott, Zachary E. and Forrest, Katherine A. and Hogan, Adam and Pham, Tony and Space, Brian}, year={2018}, pages={1761–1777} }
 @article{m. franz_djulbegovic_pham_space_2018, title={Theoretical study of the effect of halogen substitution in molecular porous materials for CO<sub>2</sub> and C<sub>2</sub>H<sub>2</sub> sorption}, volume={5}, ISSN={2372-0484}, url={http://dx.doi.org/10.3934/matersci.2018.2.226}, DOI={10.3934/matersci.2018.2.226}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations of carbondioxide (CO$_2$) and acetylene (C$_2$H$_2$) sorption were performed in MPM-1-Cl and MPM-1-Br, two robust molecular porous materials (MPMs) that were synthesized by the addition of adenine to CuX$_2$ (X = Cl or Br) by solvent diffusion. Previous experimental studies revealed that both MPMs are selective for C$_2$H$_2$ over CO$_2$ [Xie DY, et al. (2017) ${CIESC J}$ 68: 154--162]. Simulations in MPM-1-Cl and MPM-1-Br were carried out using polarizable and nonpolarizable potentials of the respective sorbates; this was done to investigate the role of explicit induction on the gas sorption mechanism in these materials. The calculated sorption isotherms and isosteric heat of adsorption ($Q_{st}$) valuesfor both sorbates are in reasonable agreement with the corresponding experimental measurements, with simulations using the polarizable models producing the closest overall agreement. The modeled CO$_2$ binding sitein both MPMs was discovered as sorption between the halide ions of two adjacent [Cu$_2$(adenine)$_4$X$_2$]$^{2+}$ (X = Cl, Br) units.In the case of C$_2$H$_2$, it was found that the sorbate molecule prefers to align along the X--Cu--Cu--X axis of the copper paddlewheels suchthat each H atom of the C$_2$H$_2$ molecule can interact favorably with the coordinated X$^-$ ions. The simulations revealed that both MPMs exhibit stronger interactions with C$_2$H$_2$ than CO$_2$, which is consistent with experimental findings. The effect of halogen substitution toward CO$_2$ and C$_2$H$_2$ sorption in two isostructural MPMs was also elucidated in our theoretical studies.}, number={2}, journal={AIMS Materials Science}, publisher={American Institute of Mathematical Sciences (AIMS)}, author={M. Franz, Douglas and Djulbegovic, Mak and Pham, Tony and Space, Brian}, year={2018}, pages={226–245} }
 @article{forrest_pham_space_2017, title={Comparing the mechanism and energetics of CO2 sorption in the SIFSIX series}, volume={19}, ISSN={1466-8033}, url={http://dx.doi.org/10.1039/c7ce00594f}, DOI={10.1039/c7ce00594f}, abstractNote={Simulations of CO2 sorption were performed in five members of the previously discovered SIFSIX series: SIFSIX-1-Cu, SIFSIX-2-Cu, SIFSIX-2-Cu-i, SIFSIX-3-Zn, and SIFSIX-3-Cu. These metal–organic materials (MOMs) consist of metal ions that are coordinated to linear ligands and are pillared with SiF62− (“SIFSIX”) ions. These MOMs mostly differ in the ligand that is used to synthesize the material, although interpenetration and substitution of the metal ion is also responsible for the formation of some members. The pore size in this series ranges from 3.54 to 13.05 A. The simulated CO2 sorption isotherms and isosteric heat of adsorption (Qst) values for all five MOMs are in good agreement with the corresponding experimental data. Consistent with experimental measurements, our simulations demonstrate that the Qst for CO2 increases as the pore size decreases in this series. It was found that SIFSIX-1-Cu and SIFSIX-2-Cu-i exhibit favorable MOM–sorbate and sorbate–sorbate interactions upon CO2 sorption, which explains why the CO2Qst increases as a function of loading in these variants. Further, SIFSIX-3-Zn and SIFSIX-3-Cu display nearly constant Qst values for all loadings considered because only one type of sorption site is present in these MOMs. Notable differences in the repulsion/dispersion and electrostatic contributions for CO2 sorption were observed in all five SIFSIX MOMs, with no particular trend upon variation of the pore size. SIFSIX-2-Cu-i exhibits the highest contributions from repulsion/dispersion interactions, while SIFSIX-3-Cu displays the highest percentage from electrostatic interactions within the series. Polarization interactions are negligible for all five members. Overall, our simulations reveal that these five SIFSIX MOMs display different CO2 sorption mechanisms and energetics. This led to differences in the sorbate induced dipole distribution and the radial distribution functions (g(r)) about the Si atoms for all MOMs.}, number={24}, journal={CrystEngComm}, publisher={Royal Society of Chemistry (RSC)}, author={Forrest, Katherine A. and Pham, Tony and Space, Brian}, year={2017}, pages={3338–3347} }
 @article{elsaidi_mohamed_simon_braun_pham_forrest_xu_banerjee_space_zaworotko_et al._2017, title={Effect of ring rotation upon gas adsorption in SIFSIX-3-M (M = Fe, Ni) pillared square grid networks}, volume={8}, ISSN={2041-6520 2041-6539}, url={http://dx.doi.org/10.1039/C6SC05012C}, DOI={10.1039/C6SC05012C}, abstractNote={Dynamic and flexible metal–organic frameworks (MOFs) that respond to external stimuli, such as stress, light, heat, and the presence of guest molecules, hold promise for applications in chemical sensing, drug delivery, gas separations, and catalysis.}, number={3}, journal={Chemical Science}, publisher={Royal Society of Chemistry (RSC)}, author={Elsaidi, Sameh K. and Mohamed, Mona H. and Simon, Cory M. and Braun, Efrem and Pham, Tony and Forrest, Katherine A. and Xu, Wenqian and Banerjee, Debasis and Space, Brian and Zaworotko, Michael J. and et al.}, year={2017}, pages={2373–2380} }
 @article{pham_forrest_franz_space_2017, title={Experimental and theoretical investigations of the gas adsorption sites in rht-metal–organic frameworks}, volume={19}, ISSN={1466-8033}, url={http://dx.doi.org/10.1039/c7ce01032j}, DOI={10.1039/c7ce01032j}, abstractNote={rht-metal–organic frameworks (MOFs) represent a highly popular class of MOFs in the world of porous crystalline materials. MOFs belonging to this family consist of M2+ ions coordinated to hexatopic organic linkers containing three coplanar isophthalate-based moieties. rht-MOFs are a promising platform of MOFs because they display open-metal sites through the [M2(O2CR)4] clusters, high surface areas, and tunable pore sizes and chemical functionalities. They have been shown to exhibit high uptake for various energy-related gases, such as H2 and CO2. Detailed insights into the gas sorption mechanisms and binding sites in these MOFs can be made by way of experimental techniques, including neutron powder diffraction (NPD) and inelastic neutron scattering (INS), and theoretical methods, such as Monte Carlo (MC) simulations and electronic structure calculations. In this highlight, we review the important experimental and theoretical studies that have been performed to investigate the favorable gas sorption sites in these MOFs. A better understanding of the gas sorption mechanisms in rht-MOFs and related structures can allow for the rational design of new materials that are tailored for specific applications.}, number={32}, journal={CrystEngComm}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Franz, Douglas M. and Space, Brian}, year={2017}, pages={4646–4665} }
 @article{zhang_zhou_pham_forrest_liu_he_wu_yildirim_chen_space_et al._2017, title={Fine Tuning of MOF-505 Analogues To Reduce Low-Pressure Methane Uptake and Enhance Methane Working Capacity}, volume={56}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201704974}, DOI={10.1002/anie.201704974}, abstractNote={Abstract We present a crystal engineering strategy to fine tune the pore chemistry and CH 4 ‐storage performance of a family of isomorphic MOFs based upon PCN‐14. These MOFs exhibit similar pore size, pore surface, and surface area (around 3000 m 2 g −1 ) and were prepared with the goal to enhance CH 4 working capacity. [Cu 2 (L2)(H 2 O) 2 ] n (NJU‐Bai 41: NJU‐Bai for Nanjing University Bai's group), [Cu 2 (L3)(H 2 O) 2 ] n (NJU‐Bai 42), and [Cu 2 (L4)(DMF) 2 ] n (NJU‐Bai 43) were prepared and we observed that the CH 4 volumetric working capacity and volumetric uptake values are influenced by subtle changes in structure and chemistry. In particular, the CH 4 working capacity of NJU‐Bai 43 reaches 198 cm 3 (STP: 273.15 K, 1 atm) cm −3 at 298 K and 65 bar, which is amongst the highest reported for MOFs under these conditions and is much higher than the corresponding value for PCN‐14 (157 cm 3 (STP) cm −3 ).}, number={38}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Zhang, Mingxing and Zhou, Wei and Pham, Tony and Forrest, Katherine A. and Liu, Wenlong and He, Yabing and Wu, Hui and Yildirim, Taner and Chen, Banglin and Space, Brian and et al.}, year={2017}, month={Aug}, pages={11426–11430} }
 @article{pham_forrest_furukawa_russina_albinati_georgiev_eckert_space_2017, title={High H2 Sorption Energetics in Zeolitic Imidazolate Frameworks}, volume={121}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/acs.jpcc.6b11466}, DOI={10.1021/acs.jpcc.6b11466}, abstractNote={A combined experimental and theoretical study of H2 sorption was carried out on two isostructural zeolitic imidazolate frameworks (ZIFs), namely ZIF-68 and ZIF-69. The former consists of Zn2+ ions that are coordinated to two 2-nitroimidazolate and two benzimidazolate linkers in a tetrahedral fashion, while 5-chlorobenzimidazolate is used in place of benzimidazolate in the latter compound. H2 sorption measurements showed that the two ZIFs display similar isotherms and isosteric heats of adsorption (Qst). The experimental initial H2 Qst value for both ZIFs was determined to be 8.1 kJ mol–1, which is quite high for materials that do not contain exposed metal centers. Molecular simulations of H2 sorption in ZIF-68 and ZIF-69 confirmed the similar H2 sorption properties between the two ZIFs, but also suggest that H2 sorption is slightly favored in ZIF-68 with regards to uptake at 77 K/1.0 atm. This work also presents inelastic neutron scattering (INS) spectra for H2 sorbed in ZIFs for the first time. The spect...}, number={3}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Furukawa, Hiroyasu and Russina, Margarita and Albinati, Alberto and Georgiev, Peter A. and Eckert, Juergen and Space, Brian}, year={2017}, month={Jan}, pages={1723–1733} }
 @article{scott_shivanna_bajpai_madden_chen_pham_forrest_hogan_space_perry iv_et al._2017, title={Highly Selective Separation of C2H2 from CO2 by a New Dichromate-Based Hybrid Ultramicroporous Material}, volume={9}, ISSN={1944-8244 1944-8252}, url={http://dx.doi.org/10.1021/acsami.6b15250}, DOI={10.1021/acsami.6b15250}, abstractNote={A new hybrid ultramicroporous material, [Ni(1,4-di(pyridine-2-yl)benzene)2(Cr2O7)]n (DICRO-4-Ni-i), has been prepared and structurally characterized. Pure gas sorption isotherms and molecular modeling of sorbate-sorbent interactions imply strong selectivity for C2H2 over CO2 (SAC). Dynamic gas breakthrough coupled with temperature-programmed desorption experiments were conducted on DICRO-4-Ni-i and two other porous materials reported to exhibit high SAC, TIFSIX-2-Cu-i and MIL-100(Fe), using a C2H2/CO2/He (10:5:85) gas mixture. Whereas CO2/C2H2 coadsorption by MIL-100(Fe) mitigated the purity of trapped C2H2, negligible coadsorption and high SAC were observed for DICRO-4-Ni-i and TIFSIX-2-Cu-i.}, number={39}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Scott, Hayley S. and Shivanna, Mohana and Bajpai, Alankriti and Madden, David G. and Chen, Kai-Jie and Pham, Tony and Forrest, Katherine A. and Hogan, Adam and Space, Brian and Perry IV, John J. and et al.}, year={2017}, month={Jan}, pages={33395–33400} }
 @article{forrest_pham_space_2017, title={Investigating gas sorption in an rht-metal–organic framework with 1,2,3-triazole groups}, volume={19}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/c7cp06128e}, DOI={10.1039/c7cp06128e}, abstractNote={Simulations of CO2 and H2 sorption were performed in an rht-metal-organic framework (MOF) that consists of Cu2+ ions coordinated to 5,5',5''-(4,4',4''-(benzene-1,3,5-triyl)tris(1H-1,2,3-triazole-4,1-diyl))triisophthalate (BTTI) linkers; it is referred to as Cu-BTTI herein. This MOF was previously synthesized and reported by three different experimental groups [Zhao et al., Sci. Rep., 2013, 3, 1149; Schröder et al., Chem. Sci., 2013, 4, 1731-1736; Hupp et al., Energy Environ. Sci., 2013, 6, 1158-1163]. This MOF is notable for the presence of open-metal sites and nitrogen-rich regions through the copper paddlewheel ([Cu2(O2CR)4]) clusters and 1,2,3-triazole groups, respectively, which allows this material to display remarkable CO2 and H2 sorption properties. All three groups report distinct experimental and theoretical gas sorption results for the MOF. In contrast to the force fields utilized in the aforementioned studies, our simulations include explicit many-body polarization interactions, which was important to reproduce sorption onto the open-metal sites. Simulations using polarizable potentials for the MOF and sorbates generated sorption isotherms and isosteric heat of adsorption (Qst) values that are outstanding agreement with the corresponding experimental data for all three groups; this is in contrast to the theoretical results presented in the respective original references. The simulations carried out in the previous studies often looked reasonable but they missed a key feature of the sorption process that lead to unreliable results. Analysis of the radial distribution function (g(r)) about the open-metal sites and examination of the modeled structure reveal that the CO2 and H2 molecules prefer to sorb onto two unique types of Cu2+ ions that exhibit the highest partial positive charges. Sorption was also observed within the corners of the truncated tetrahedral (T-Td) cages and onto the 1,2,3-triazole groups of the linkers for both sorbates. Overall, this study demonstrates how utilizing a classical polarizable force field led to the reproduction of experimental observables and allowed for an accurate description of the sorption mechanism in this MOF that is an important member of the rht-MOF family.}, number={43}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Forrest, Katherine A. and Pham, Tony and Space, Brian}, year={2017}, pages={29204–29221} }
 @article{pham_forrest_franz_guo_chen_space_2017, title={Predictive models of gas sorption in a metal–organic framework with open-metal sites and small pore sizes}, volume={19}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/c7cp02767b}, DOI={10.1039/c7cp02767b}, abstractNote={Simulations of CO2 and H2 sorption were performed in UTSA-20, a metal-organic framework (MOF) having zyg topology and composed of Cu2+ ions coordinated to 3,3',3'',5,5',5''-benzene-1,3,5-triyl-hexabenzoate (BHB) linkers. Previous experimental studies have shown that this MOF displays remarkable CO2 sorption properties and exhibits one of the highest gravimetric H2 uptakes at 77 K/1.0 atm (2.9 wt%) [Z. Guo, et al. Angew. Chem., Int. Ed., 2011, 50, 3178-3181]. For both sorbates, the simulations were executed with the inclusion of explicit many-body polarization interactions, which was necessary to reproduce sorption onto the open-metal sites. Non-polarizable potentials were also utilized for simulations of CO2 sorption as a control. The simulated excess sorption isotherms for both CO2 and H2 are in very good agreement with the corresponding experimental data over a wide range of temperatures and pressures, thus demonstrating the accuracy and predictive power of the polarizable potentials used herein. The theoretical isosteric heat of adsorption (Qst) values are also in good agreement with the newly reported experimental Qst values for the respective sorbates in UTSA-20. Sorption onto the more positively charged Cu2+ ion of the [Cu2(O2CR)4] cluster was observed for both CO2 and H2. However, a binding site with energetics comparable to that for an open-metal site was also discovered for both sorbates. A radial distribution function (g(r)) analysis about the preferential Cu2+ ions for CO2 and H2 revealed that both sorbates display different trends for the relative occupancy about such sites upon increasing/decreasing the pressure in the MOF. Overall, this study provides insights into the CO2 and H2 sorption mechanisms in this MOF containing open-metal sites and small pore sizes for the first time through a classical polarizable force field.}, number={28}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Franz, Douglas M. and Guo, Zhiyong and Chen, Banglin and Space, Brian}, year={2017}, pages={18587–18602} }
 @article{bajpai_o'nolan_madden_chen_pham_kumar_lusi_perry_space_zaworotko_2017, title={The effect of centred versus offset interpenetration on C2H2 sorption in hybrid ultramicroporous materials}, volume={53}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/C7CC05882A}, DOI={10.1039/C7CC05882A}, abstractNote={Fine-tuning of hybrid ultramicroporous materials (HUMs) can significantly impact their gas sorption performance. This study reveals that offset interpenetration can be antagonistic with respect to C2H2 separation from C2H2/C2H4 gas mixtures.}, number={84}, journal={Chem. Commun.}, publisher={Royal Society of Chemistry (RSC)}, author={Bajpai, Alankriti and O'Nolan, Daniel and Madden, David G. and Chen, Kai-Jie and Pham, Tony and Kumar, Amrit and Lusi, Matteo and Perry, John J. and Space, Brian and Zaworotko, Michael J.}, year={2017}, pages={11592–11595} }
 @article{pham_forrest_mostrom_hunt_furukawa_eckert_space_2017, title={The rotational dynamics of H2 adsorbed in covalent organic frameworks}, volume={19}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/c7cp00924k}, DOI={10.1039/c7cp00924k}, abstractNote={A combined inelastic neutron scattering (INS) and theoretical study was carried out on H2 adsorbed in two covalent organic framework (COF) materials: COF-1 and COF-102. These COFs are synthesized from self-condensation reactions of 1,4-benzenediboronic acid (BDBA) and tetra(4-(dihydroxy)borylphenyl)methane (TBPM) molecules, respectively. Molecular simulations of H2 adsorption in COF-1 revealed that the H2 molecules occupy the region between two eclipsed layers of the COF. The most favorable H2 binding site in COF-1 is located between two B3O3 clusters of the eclipsed layers. Two distinct H2 binding sites were identified in COF-102 from the simulations: the B3O3 clusters and the phenyl rings of the tetraphenylmethyl units. Two-dimensional quantum rotation calculations for H2 adsorbed at the considered sites in both COFs resulted in rotational transitions that are in good agreement with those that appear in the corresponding INS spectra. Such calculations were important for interpreting the INS spectra in these materials. Calculation of the rotational potential energy surface for H2 bound at the most favorable adsorption site in COF-1 and COF-102 revealed unusually high rotational barriers that are attributed to the nature of the B3O3 rings. The values for these barriers to rotation are greater than or comparable to those observed in some metal-organic frameworks (MOFs) that possess open-metal sites. This study demonstrates the power of using INS experiments in conjunction with theoretical calculations to gain valuable insights into the nature of the binding sites and, for the first time, the rotational dynamics of H2 adsorbed in COFs.}, number={20}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Mostrom, Matthew and Hunt, Joseph R. and Furukawa, Hiroyasu and Eckert, Juergen and Space, Brian}, year={2017}, pages={13075–13082} }
 @article{franz_forrest_pham_space_2016, title={Accurate H2 Sorption Modeling in the rht-MOF NOTT-112 Using Explicit Polarization}, volume={16}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/acs.cgd.6b01058}, DOI={10.1021/acs.cgd.6b01058}, abstractNote={Hydrogen sorption was characterized theoretically in NOTT-112, an rht-metal–organic framework (MOF) that consists of Cu2+ ions coordinated to 1,3,5-tris(3′,5′-dicarboxy[1,1′-biphenyl]-4-yl)benzene ligands. Grand canonical Monte Carlo (GCMC) simulations of H2 sorption were performed using three different sorbate potentials of increasing complexity to elucidate the mechanism of interaction in NOTT-112. Reasonable agreement with the experimental H2 sorption isotherms, isosteric heats of adsorption (Qst), and H2–Cu2+ distances was obtained with the model that includes explicit many-body polarization. This highlights the physical importance of induction in H2 sorption in MOFs with open-metal sites. The two Cu2+ ions within the paddlewheels in NOTT-112 have distinct electrostatic profiles and sorption characteristics. The Cu2+ ions projecting into the cuboctahedral (cub–Oh) cage of the MOF are more electropositive than the Cu2+ ions projecting toward the organic linker, and therefore serve as the initial loadin...}, number={10}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Franz, Douglas and Forrest, Katherine A. and Pham, Tony and Space, Brian}, year={2016}, month={Sep}, pages={6024–6032} }
 @article{pham_forrest_space_2016, title={An unusual H2 sorption mechanism in PCN-14: insights from molecular simulation}, volume={18}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/c6cp02650h}, DOI={10.1039/c6cp02650h}, abstractNote={Simulations of H2 sorption were performed in PCN-14, a metal-organic framework (MOF) that consists of Cu(2+) ions coordinated to 5,5'-(9,10-anthracenediyl)diisophthalate (adip) linkers. This MOF displays an excess H2 uptake of 2.70 wt% at 77 K and 1.0 atm and an initial H2Qst value of 8.6 kJ mol(-1) according to previous experimental measurements. The experimental H2 sorption isotherms and Qst values in PCN-14 were reproduced in simulations using well-known H2 potentials that have been widely used for MOF-H2 theoretical studies. H2 sorption in PCN-14 was dominated by repulsion/dispersion energetics; this allowed the experimental observables to be reproduced by a model that includes only Lennard-Jones parameters. The most energetically favorable H2 sorption site in PCN-14 corresponds to sorption within a small cage that is enclosed by three [Cu2(O2CR)4] units and three adip linkers. The anthracenyl rings of the adip linkers represent the secondary sorption sites within the MOF. In contrast to expectations, sorption of H2 onto the Cu(2+) ions of the copper paddlewheels was not observed within the simulations at low loading. The simulations revealed that the open-metal sites in PCN-14 were occupied at high loading. Control simulations of H2 sorption in PCN-14 for different cases in which the partial positive charge of one of the paddlewheel Cu(2+) ions was increased relative to the other revealed that sorption onto the open-metal sites can be captured if there is a very high positive charge on the metal. Otherwise, the calculated partial charge for the Cu(2+) ions in PCN-14 in this work was not high enough in magnitude to facilitate strong H2-metal interactions in simulation. This study shows the power of using molecular simulations to elucidate an unusual H2 sorption behavior in a MOF.}, number={31}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Space, Brian}, year={2016}, pages={21421–21430} }
 @article{chen_scott_madden_pham_kumar_bajpai_lusi_forrest_space_perry_et al._2016, title={Benchmark C 2 H 2 /CO 2 and CO 2 /C 2 H 2 Separation by Two Closely Related Hybrid Ultramicroporous Materials}, volume={1}, ISSN={2451-9294}, url={http://dx.doi.org/10.1016/j.chempr.2016.10.009}, DOI={10.1016/j.chempr.2016.10.009}, abstractNote={The removal of CO2 impurities from C2H2-containing gas mixtures is an important step in purifying C2H2, a feedstock chemical used in the production of several commodity chemicals. However, that C2H2 and CO2 exhibit similar size and physicochemical properties makes their separation by physisorption extremely difficult. In this work, we detail how two hybrid ultramicroporous materials (HUMs)—known variant SIFSIX-3-Ni and variant TIFSIX-2-Cu-i—exhibit exceptional CO2/C2H2 and C2H2/CO2 selectivity, respectively. SIFSIX-3-Ni sets a benchmark for CO2/C2H2 selectivity at low partial pressures, whereas TIFSIX-2-Cu-i ranks among the best porous materials in the context of C2H2/CO2 selectivity. The performance of these HUMs was confirmed by real-time dynamic breakthrough experiments. To our knowledge, such yin-yang inversion of selectivity in closely related compounds is unprecedented. We attribute this to the distinct sorbate binding sites in SIFSIX-3-Ni and TIFSIX-2-Cu-i, as revealed by modeling studies.}, number={5}, journal={Chem}, publisher={Elsevier BV}, author={Chen, Kai-Jie and Scott, Hayley S. and Madden, David G. and Pham, Tony and Kumar, Amrit and Bajpai, Alankriti and Lusi, Matteo and Forrest, Katherine A. and Space, Brian and Perry, John J., IV and et al.}, year={2016}, month={Nov}, pages={753–765} }
 @article{elsaidi_mohamed_pham_hussein_wojtas_zaworotko_space_2016, title={Crystal Engineering of a 4,6-c fsc Platform That Can Serve as a Carbon Dioxide Single-Molecule Trap}, volume={16}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/acs.cgd.5b01632}, DOI={10.1021/acs.cgd.5b01632}, abstractNote={We report herein a crystal engineering strategy that affords a new and versatile metal–organic material (MOM) platform that is tunable in terms of both pore size and functionality. This platform is comprised of two long-known molecular building blocks (MBBs) that alternate to form a cationic square grid lattice. The MBBs, [Cu(AN)4]2+ (AN = aromatic nitrogen donor), and [Cu2(CO2R)4] square paddlewheel moieties are connected by five different fs, L1–L5, that contain both AN and carboxylate moieties. The resulting square grid nets formed from alternating [Cu(AN)4]2+ and [Cu2(CO2R)4] moieties are pillared at the axial sites of the [Cu(AN)4]2+ MBBs with dianionic pillars to form neutral 3D 4,6-connected fsc (four, six type c) nets. Pore size control in this family of fsc nets was exerted by varying the length of the ligand, whereas pore chemistry was defined by the presence of unsaturated metal centers (UMCs) and either inorganic or organic pillars. 1,5-Naphthalenedisulfonate (NDS) anions pillar in an angular ...}, number={2}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Elsaidi, Sameh K. and Mohamed, Mona H. and Pham, Tony and Hussein, Taher and Wojtas, Lukasz and Zaworotko, Michael J. and Space, Brian}, year={2016}, month={Jan}, pages={1071–1080} }
 @article{scott_ogiwara_chen_madden_pham_forrest_space_horike_perry iv_kitagawa_et al._2016, title={Crystal engineering of a family of hybrid ultramicroporous materials based upon interpenetration and dichromate linkers}, volume={7}, ISSN={2041-6520 2041-6539}, url={http://dx.doi.org/10.1039/c6sc01385f}, DOI={10.1039/c6sc01385f}, abstractNote={A new platform of primitive cubic (pcu) topology hybrid ultramicroporous materials comprising dichromate anion pillars is reported.}, number={8}, journal={Chemical Science}, publisher={Royal Society of Chemistry (RSC)}, author={Scott, Hayley S. and Ogiwara, Naoki and Chen, Kai-Jie and Madden, David G. and Pham, Tony and Forrest, Katherine and Space, Brian and Horike, Satoshi and Perry IV, John J. and Kitagawa, Susumu and et al.}, year={2016}, pages={5470–5476} }
 @article{pham_forrest_eckert_space_2016, title={Dramatic Effect of the Electrostatic Parameters on H2 Sorption in an M-MOF-74 Analogue}, volume={16}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/acs.cgd.5b01434}, DOI={10.1021/acs.cgd.5b01434}, abstractNote={Simulations of H2 sorption were performed in Cu-MOF-74, a recent addition to the M-MOF-74 series. Electronic structure calculations revealed that the Cu2+ ions exhibit an unusually low partial positive charge distribution in Cu-MOF-74, which is a direct consequence of the Jahn–Teller effect. This is in contrast to the charge environment for the metal ions in some of the other M-MOF-74 variants as determined in previous work [Pham, T.; J. Phys. Chem. C 2015, 119, 1078−1090]. Because of the low magnitude of the partial charges of the Cu2+ ions in Cu-MOF-74, this MOF displays the lowest H2 uptake and Qst values of the M-MOF-74 series, which is consistent with what was observed experimentally for H2 sorption in this series of MOFs. Control simulations of H2 sorption in a nonphysical Cu-MOF-74 variant were performed in which a set of calculated partial charges, appropriate for one of the other M-MOF-74 analogues, were used. These simulations utilize a much higher partial positive charge for the metal ions and,...}, number={2}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Eckert, Juergen and Space, Brian}, year={2016}, month={Dec}, pages={867–874} }
 @article{pham_forrest_space_eckert_2016, title={Dynamics of H2 adsorbed in porous materials as revealed by computational analysis of inelastic neutron scattering spectra}, volume={18}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/c6cp01863g}, DOI={10.1039/c6cp01863g}, abstractNote={The inelastic scattering of neutrons from adsorbed H2 is an effective and highly sensitive method for obtaining molecular level information on the type and nature of H2 binding sites in porous materials. While these inelastic neutron scattering (INS) spectra of the hindered rotational and translational excitations on the adsorbed H2 contain a significant amount of information, much of this can only be reliably extracted by means of a detailed analysis of the spectra through the utilization of models and theoretical calculations. For instance, the rotational tunneling transitions observed in the INS spectra can be related to a value for the barrier to rotation for the adsorbed H2 with the use of a simple phenomenological model. Since such an analysis is dependent on the model, it is far more desirable to use theoretical methods to compute a potential energy surface (PES), from which the rotational barriers for H2 adsorbed at a particular site can be determined. Rotational energy levels and transitions for the hindered rotor can be obtained by quantum dynamics calculations and compared directly with experiment with an accuracy subject only to the quality of the theoretical PES. In this paper, we review some of the quantum and classical mechanical calculations that have been performed on H2 adsorbed in various porous materials, such as clathrate hydrates, zeolites, and metal-organic frameworks (MOFs). The principal aims of these calculations have been the interpretation of the INS spectra for adsorbed H2 along with the extraction of atomic level details of its interaction with the host. We describe calculations of the PES used for two-dimensional quantum rotation as well as rigorous five-dimensional quantum coupled translation-rotation dynamics, and demonstrate that the combination of INS measurements and computational modeling can provide important and detailed insights into the molecular mechanism of H2 adsorption in porous materials.}, number={26}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Space, Brian and Eckert, Juergen}, year={2016}, pages={17141–17158} }
 @article{pham_forrest_falcão_eckert_space_2016, title={Exceptional H2 sorption characteristics in a Mg2+-based metal–organic framework with small pores: insights from experimental and theoretical studies}, volume={18}, ISSN={1463-9076 1463-9084}, url={http://dx.doi.org/10.1039/c5cp05906b}, DOI={10.1039/c5cp05906b}, abstractNote={Experimental sorption measurements, inelastic neutron scattering (INS), and theoretical studies of H2 sorption were performed in α-[Mg3(O2CH)6], a metal-organic framework (MOF) that consists of a network of Mg(2+) ions coordinated to formate ligands. The experimental H2 uptake at 77 K and 1.0 atm was observed to be 0.96 wt%, which is quite impressive for a Mg(2+)-based MOF that has a BET surface area of only 150 m(2) g(-1). Due to the presence of small pore sizes in the MOF, the isosteric heat of adsorption (Qst) value was observed to be reasonably high for a material with no open-metal sites (ca. 7.0 kJ mol(-1)). The INS spectra for H2 in α-[Mg3(O2CH)6] is very unusual for a porous material, as there exist several different peaks that occur below 10 meV. Simulations of H2 sorption in α-[Mg3(O2CH)6] revealed that the H2 molecules sorbed at three principal locations within the small pores of the framework. It was discovered through the simulations and two-dimensional quantum rotation calculations that different groups of peaks correspond to particular sorption sites in the material. However, for H2 sorbed at a specific site, it was observed that differences in the positions and angular orientations led to distinctions in the rotational tunnelling transitions; this led to a total of eight identified sites. An extremely high rotational barrier was calculated for H2 sorbed at the most favorable site in α-[Mg3(O2CH)6] (81.59 meV); this value is in close agreement to that determined using an empirical phenomenological model (75.71 meV). This rotational barrier for H2 exceeds those for various MOFs that contain open-metal sites and is currently the highest yet for a neutral MOF. This study highlights the synergy between experiment and theory to extract useful and important atomic level details on the remarkable sorption mechanism for H2 in a MOF with small pore sizes.}, number={3}, journal={Physical Chemistry Chemical Physics}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Falcão, Eduardo H. L. and Eckert, Juergen and Space, Brian}, year={2016}, pages={1786–1796} }
 @article{mohamed_elsaidi_pham_forrest_schaef_hogan_wojtas_xu_space_zaworotko_et al._2016, title={Hybrid Ultra-Microporous Materials for Selective Xenon Adsorption and Separation}, volume={55}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201602287}, DOI={10.1002/anie.201602287}, abstractNote={The demand for Xe/Kr separation continues to grow due to the industrial significance of high-purity Xe gas. Current separation processes rely on energy intensive cryogenic distillation. Therefore, less energy intensive alternatives, such as physisorptive separation, using porous materials, are required. Herein we show that an underexplored class of porous materials called hybrid ultra-microporous materials (HUMs) affords new benchmark selectivity for Xe separation from Xe/Kr mixtures. The isostructural materials, CROFOUR-1-Ni and CROFOUR-2-Ni, are coordination networks that have coordinatively saturated metal centers and two distinct types of micropores, one of which is lined by CrO4 (2-) (CROFOUR) anions and the other is decorated by the functionalized organic linker. These nets offer unprecedented selectivity towards Xe. Modelling indicates that the selectivity of these nets is tailored by synergy between the pore size and the strong electrostatics afforded by the CrO4 (2-) anions.}, number={29}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Mohamed, Mona H. and Elsaidi, Sameh K. and Pham, Tony and Forrest, Katherine A. and Schaef, Herbert T. and Hogan, Adam and Wojtas, Lukasz and Xu, Wenqian and Space, Brian and Zaworotko, Michael J. and et al.}, year={2016}, month={May}, pages={8285–8289} }
 @article{pham_forrest_chen_kumar_zaworotko_space_2016, title={Theoretical Investigations of CO2 and H2 Sorption in Robust Molecular Porous Materials}, volume={32}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/acs.langmuir.6b03161}, DOI={10.1021/acs.langmuir.6b03161}, abstractNote={Molecular simulations of CO2 and H2 sorption were performed in MPM-1-Cl and MPM-1-TIFSIX, two robust molecular porous materials (MPMs) with the empirical formula [Cu2(adenine)4Cl2]Cl2 and [Cu2(adenine)4(TiF6)2], respectively. Recent experimental studies have shown that MPM-1-TIFSIX displayed higher CO2 uptake and isosteric heat of adsorption (Qst) than MPM-1-Cl [Nugent, P. S.; et al. J. Am. Chem. Soc. 2013, 135, 10950-10953]. This was verified through the simulations executed herein, as the presented simulated CO2 sorption isotherms and Qst values are in very good agreement with the corresponding experimental data for both MPMs. We also report experimental H2 sorption data in both MPMs. Experimental studies revealed that MPM-1-TIFSIX exhibits high H2 uptake at low loadings and an initial H2 Qst value of 9.1 kJ mol-1. This H2 Qst value is greater than that for a number of existing metal-organic frameworks (MOFs) and represents the highest yet reported for a MPM. The remarkable H2 sorption properties for MPM-1-TIFSIX have been confirmed through our simulations. The modeling studies revealed that only one principal sorption site is present for CO2 and H2 in MPM-1-Cl, which is sorption onto the Cl- counterions within the large channels. In contrast, three different sorption sites were discovered for both CO2 and H2 in MPM-1-TIFSIX: (1) between two TIFSIX groups within a small passage connecting the large channels, (2) onto the TIFSIX ions lining the large channels, and (3) within the small channels. This study illustrates the detailed insights that molecular simulations can provide on the CO2 and H2 sorption mechanism in MPMs.}, number={44}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Chen, Kai-Jie and Kumar, Amrit and Zaworotko, Michael J. and Space, Brian}, year={2016}, month={Oct}, pages={11492–11505} }
 @article{bajpai_scott_pham_chen_space_lusi_perry_zaworotko_2016, title={Towards an understanding of the propensity for crystalline hydrate formation by molecular compounds}, volume={3}, ISSN={2052-2525}, url={http://dx.doi.org/10.1107/S2052252516015633}, DOI={10.1107/S2052252516015633}, abstractNote={The propensity for crystalline hydrate formation by molecular compounds that are devoid of strong hydrogen-bond donors has been analyzed and rationalized through a Cambridge Structural Database (CSD) survey, systematic hydrate screening experiments and computational studies.}, number={6}, journal={IUCrJ}, publisher={International Union of Crystallography (IUCr)}, author={Bajpai, Alankriti and Scott, Hayley S. and Pham, Tony and Chen, Kai-Jie and Space, Brian and Lusi, Matteo and Perry, Miranda L. and Zaworotko, Michael J.}, year={2016}, month={Oct}, pages={430–439} }
 @article{chen_madden_pham_forrest_kumar_yang_xue_space_perry_zhang_et al._2016, title={Tuning Pore Size in Square-Lattice Coordination Networks for Size-Selective Sieving of CO2}, volume={55}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201603934}, DOI={10.1002/anie.201603934}, abstractNote={Porous materials capable of selectively capturing CO2 from flue-gases or natural gas are of interest in terms of rising atmospheric CO2 levels and methane purification. Size-exclusive sieving of CO2 over CH4 and N2 has rarely been achieved. Herein we show that a crystal engineering approach to tuning of pore-size in a coordination network, [Cu(quinoline-5-carboxyate)2 ]n (Qc-5-Cu) ena+bles ultra-high selectivity for CO2 over N2 (SCN ≈40 000) and CH4 (SCM ≈3300). Qc-5-Cu-sql-β, a narrow pore polymorph of the square lattice (sql) coordination network Qc-5-Cu-sql-α, adsorbs CO2 while excluding both CH4 and N2 . Experimental measurements and molecular modeling validate and explain the performance. Qc-5-Cu-sql-β is stable to moisture and its separation performance is unaffected by humidity.}, number={35}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Chen, Kai-Jie and Madden, David G. and Pham, Tony and Forrest, Katherine A. and Kumar, Amrit and Yang, Qing-Yuan and Xue, Wei and Space, Brian and Perry, John J., IV and Zhang, Jie-Peng and et al.}, year={2016}, month={Jul}, pages={10268–10272} }
 @article{elsaidi_mohamed_schaef_kumar_lusi_pham_forrest_space_xu_halder_et al._2015, title={Correction: Hydrophobic pillared square grids for selective removal of CO2 from simulated flue gas}, volume={51}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c5cc90503f}, DOI={10.1039/c5cc90503f}, abstractNote={Correction for 'Hydrophobic pillared square grids for selective removal of CO2 from simulated flue gas' by Sameh K. Elsaidi et al., Chem. Commun., 2015, 51, 15530-15533.}, number={94}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Elsaidi, Sameh K. and Mohamed, Mona H. and Schaef, Herbert T. and Kumar, Amrit and Lusi, Matteo and Pham, Tony and Forrest, Katherine A. and Space, Brian and Xu, Wenqian and Halder, Gregory J. and et al.}, year={2015}, pages={16872–16872} }
 @article{zhang_li_krishna_wu_ma_shi_pham_forrest_space_ma_2015, title={Highly selective adsorption of ethylene over ethane in a MOF featuring the combination of open metal site and π-complexation}, volume={51}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c4cc09774b}, DOI={10.1039/c4cc09774b}, abstractNote={The introduction of the combination of open metal site (OMS) and π-complexation into MOF has led to very high ethylene-ethane adsorption selectivity at 318 K, as illustrated in the context of MIL-101-Cr-SO3Ag. The interactions with ethylene from both OMS and π-complexation in MIL-101-Cr-SO3Ag have been investigated by in situ IR spectroscopic studies and computational calculations, which suggest that π-complexation contributes dominantly to the high ethylene-ethane adsorption selectivity.}, number={13}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Zhang, Yiming and Li, Baiyan and Krishna, Rajamani and Wu, Zili and Ma, Dingxuan and Shi, Zhan and Pham, Tony and Forrest, Katherine and Space, Brian and Ma, Shengqian}, year={2015}, pages={2714–2717} }
 @article{elsaidi_mohamed_schaef_kumar_lusi_pham_forrest_space_xu_halder_et al._2015, title={Hydrophobic pillared square grids for selective removal of CO2 from simulated flue gas}, volume={51}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c5cc06577a}, DOI={10.1039/c5cc06577a}, abstractNote={Capture of CO2 from flue gas is considered to be a feasible approach to mitigate the effects of anthropogenic emission of CO2. Herein we report that an isostructural family of metal organic materials (MOMs) of general formula [M(linker)2(pillar)], linker = pyrazine, pillar = hexaflourosilicate and M = Zn, Cu, Ni and Co exhibits highly selective removal of CO2 from dry and wet simulated flue gas. Two members of the family, M = Ni and Co, SIFSIX-3-Ni and SIFSIX-3-Co, respectively, are reported for the first time and compared with the previously reported Zn and Cu analogs.}, number={85}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Elsaidi, Sameh K. and Mohamed, Mona H. and Schaef, Herbert T. and Kumar, Amrit and Lusi, Matteo and Pham, Tony and Forrest, Katherine A. and Space, Brian and Xu, Wenqian and Halder, Gregory J. and et al.}, year={2015}, pages={15530–15533} }
 @article{forrest_pham_georgiev_embs_waggoner_hogan_humphrey_eckert_space_2015, title={Inelastic Neutron Scattering and Theoretical Studies of H2Sorption in a Dy(III)-Based Phosphine Coordination Material}, volume={27}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/acs.chemmater.5b02747}, DOI={10.1021/acs.chemmater.5b02747}, abstractNote={A combined inelastic neutron scattering (INS) and theoretical study of H2 sorption was performed in PCM-16, a phosphine coordination material (PCM) with the empirical formula [(CH3)2NH2][Dy2(tctpo)2(O2CH)] (tctpo = tris(p-carboxylato)triphenylphosphine oxide). INS measurements at different loadings of H2 revealed a peak occurring at low rotational tunnelling energies (ca. 5–8 meV), which corresponds to a high barrier to rotation and, therefore, a strong interaction with the host. Molecular simulations of H2 sorption in PCM-16 revealed that the H2 molecules sorbed at two main sites in the material: (1) the (CH3)2NH2+ counterions and (2) within the small pores of the framework. Two-dimensional quantum rotation calculations revealed that the peak occurring from approximately 5–8 meV in the INS spectra for PCM-16 is associated with sorption onto the (CH3)2NH2+ ions. These counterions provide for the strongest H2 sorption sites in the material, which corresponds to an isosteric heat of adsorption (Qst) value o...}, number={22}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Forrest, Katherine A. and Pham, Tony and Georgiev, Peter A. and Embs, Jan Peter and Waggoner, Nolan W. and Hogan, Adam and Humphrey, Simon M. and Eckert, Juergen and Space, Brian}, year={2015}, month={Nov}, pages={7619–7626} }
 @article{forrest_pham_georgiev_pinzan_cioce_unruh_eckert_space_2015, title={Investigating H2Sorption in a Fluorinated Metal–Organic Framework with Small Pores Through Molecular Simulation and Inelastic Neutron Scattering}, volume={31}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/acs.langmuir.5b01664}, DOI={10.1021/acs.langmuir.5b01664}, abstractNote={Simulations of H2 sorption were performed in a metal-organic framework (MOF) consisting of Zn(2+) ions coordinated to 1,2,4-triazole and tetrafluoroterephthalate ligands (denoted [Zn(trz)(tftph)] in this work). The simulated H2 sorption isotherms reported in this work are consistent with the experimental data for the state points considered. The experimental H2 isosteric heat of adsorption (Qst) values for this MOF are approximately 8.0 kJ mol(-1) for the considered loading range, which is in the proximity of those determined from simulation. The experimental inelastic neutron scattering (INS) spectra for H2 in [Zn(trz)(tftph)] reveal at least two peaks that occur at low energies, which corresponds to high barriers to rotation for the respective sites. The most favorable sorption site in the MOF was identified from the simulations as sorption in the vicinity of a metal-coordinated H2O molecule, an exposed fluorine atom, and a carboxylate oxygen atom in a confined region in the framework. Secondary sorption was observed between the fluorine atoms of adjacent tetrafluoroterephthalate ligands. The H2 molecule at the primary sorption site in [Zn(trz)(tftph)] exhibits a rotational barrier that exceeds that for most neutral MOFs with open-metal sites according to an empirical phenomenological model, and this was further validated by calculating the rotational potential energy surface for H2 at this site.}, number={26}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={Forrest, Katherine A. and Pham, Tony and Georgiev, Peter A. and Pinzan, Florian and Cioce, Christian R. and Unruh, Tobias and Eckert, Juergen and Space, Brian}, year={2015}, month={Jun}, pages={7328–7336} }
 @article{scott_bajpai_chen_pham_space_perry_zaworotko_2015, title={Novel mode of 2-fold interpenetration observed in a primitive cubic network of formula [Ni(1,2-bis(4-pyridyl)acetylene)2(Cr2O7)]n}, volume={51}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c5cc05866j}, DOI={10.1039/c5cc05866j}, abstractNote={A primitive cubic (pcu) network of formula [Ni(1,2-bis(4-pyridyl)acetylene)2(Cr2O7)]n, , has been synthesised and found to exhibit a novel type of inclined 2-fold interpenetration and an isosteric heat of adsorption (Q(st)) of 30.5 kJ mol(-1) towards CO2 at zero loading. Q(st) is relatively high in the broad context but less than that observed in related hybrid ultramicroporous materials, a feature that can be understood after studying pore structure and molecular simulations of CO2 adsorption.}, number={80}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Scott, Hayley S. and Bajpai, Alankriti and Chen, Kai-Jie and Pham, Tony and Space, Brian and Perry, John J. and Zaworotko, Michael J.}, year={2015}, pages={14832–14835} }
 @article{gao_cai_pham_forrest_hogan_nugent_williams_wojtas_luebke_weseliński_et al._2015, title={Remote Stabilization of Copper Paddlewheel Based Molecular Building Blocks in Metal–Organic Frameworks}, volume={27}, ISSN={0897-4756 1520-5002}, url={http://dx.doi.org/10.1021/acs.chemmater.5b00084}, DOI={10.1021/acs.chemmater.5b00084}, abstractNote={Copper paddlewheel based molecular building blocks (MBBs) are ubiquitous and have been widely employed for the construction of highly porous metal–organic frameworks (MOFs). However, most copper paddlewheel based MOFs fail to retain their structural integrity in the presence of water. This instability is directly correlated to the plausible displacement of coordinating carboxylates in the copper paddlewheel MBB, [Cu2(O2C−)4], by the strongly coordinating water molecules. In this comprehensive study, we illustrate the chemical stability control in the rht-MOF platform via strengthening the coordinating bonds within the triangular inorganic MBB, [Cu3O(N4–x(CH)xC−)3] (x = 0, 1, or 2). Remotely, the chemical stabilization propagated into the paddlewheel MBB to afford isoreticular rht-MOFs with remarkably enhanced water/chemical stabilities compared to the prototypal rht-MOF-1.}, number={6}, journal={Chemistry of Materials}, publisher={American Chemical Society (ACS)}, author={Gao, Wen-Yang and Cai, Rong and Pham, Tony and Forrest, Katherine A. and Hogan, Adam and Nugent, Patrick and Williams, Kia and Wojtas, Lukasz and Luebke, Ryan and Weseliński, Łukasz J. and et al.}, year={2015}, month={Mar}, pages={2144–2151} }
 @article{gao_pham_forrest_space_wojtas_chen_ma_2015, title={The local electric field favours more than exposed nitrogen atoms on CO2 capture: a case study on the rht-type MOF platform}, volume={51}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c5cc02573g}, DOI={10.1039/c5cc02573g}, abstractNote={Two rht-type metal-organic frameworks (MOFs) based upon the tetrazolate moiety and pyrazolate moiety, respectively, have been investigated for carbon dioxide (CO2) adsorption and selective adsorption of CO2 over CH4, which shows that the rht-MOF featuring the pyrazolate moiety demonstrates superior performances compared to the rht-MOF based on the tetrazolate moiety. In spite of more exposed nitrogen atoms in the tetrazolate-based rht-MOF, the counter-intuitive observations of CO2 capture in the two rht-MOFs were interpreted by computational studies, which reveal that the local electric field favours more than the richness of exposed nitrogen atoms for the interactions with CO2 molecules.}, number={47}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Gao, Wen-Yang and Pham, Tony and Forrest, Katherine A. and Space, Brian and Wojtas, Lukasz and Chen, Yu-Sheng and Ma, Shengqian}, year={2015}, pages={9636–9639} }
 @article{pham_forrest_gao_ma_space_2015, title={Theoretical Insights into the Tuning of Metal Binding Sites of Paddlewheels in rht-Metal-Organic Frameworks}, volume={16}, ISSN={1439-4235}, url={http://dx.doi.org/10.1002/cphc.201500504}, DOI={10.1002/cphc.201500504}, abstractNote={Theoretical investigations of CO2 sorption are performed in four members of the highly tunable rht-metal-organic framework (MOF) platform. rht-MOFs contain two Cu(2+) ions that comprise the metal paddlewheels and both are in chemically distinct environments. Indeed, one type of Cu(2+) ion faces toward the center of the linker whereas the other type faces away from the center of the linker. Electronic structure calculations on the series of rht-MOFs demonstrate that one of the Cu(2+) ions has a consistently higher charge magnitude relative to the other. As a consequence, the Cu(2+) ion with the higher partial positive charge acts as the favored sorbate binding site at initial loading as revealed by grand canonical Monte Carlo (GCMC) simulations that include many-body polarization. It was found that the charge distribution about the copper paddlewheels is dependent on the type of functional groups present on the linker. This study demonstrates how the binding site about the metal paddlewheels in the rht-MOF platform can be controlled by changing the functionality on the organic ligand.}, number={15}, journal={ChemPhysChem}, publisher={Wiley}, author={Pham, Tony and Forrest, Katherine A. and Gao, Wen-Yang and Ma, Shengqian and Space, Brian}, year={2015}, month={Aug}, pages={3170–3179} }
 @article{green_space_2015, title={Time Correlation Function Modeling of Third-Order Sum Frequency Vibrational Spectroscopy of a Charged Surface/Water Interface}, volume={119}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/jp509647w}, DOI={10.1021/jp509647w}, abstractNote={Sum frequency vibrational spectroscopy (SFVS), a second-order optical process, is interface-specific in the dipole approximation [Perry, A.; Neipert, C.; Moore, P.; Space, B. Chem. Rev. 2006, 106, 1234-1258; Richmond, G. L. Chem. Rev. 2002, 102, 2693-2724; Byrnes, S. J.; Geissler, P. L.; Shen, Y. R. Chem. Phys. Lett. 2011, 516, 115-124]. At charged interfaces, the experimentally detected signal is a combination of enhanced second-order and static-field-induced third-order contributions due to the existence of a static field. Evidence of the importance/relative magnitude of this third-order contribution is seen in the literature [Ong, S.; Zhao, X.; Eisenthal, K. B. Chem. Phys. Lett. 1992, 191, 327-335; Zhao, X.; Ong, S.; Eisenthal, K. B. Chem. Phys. Lett. 1993, 202, 513-520; Shen, Y. R. Appl. Phys. B: Laser Opt. 1999, 68, 295-300], but a molecularly detailed approach to separately calculating the second- and third-order contributions is difficult to construct. Recent work presented a novel molecular dynamics (MD)-based theory that provides a direct means to calculate the third-order contributions to SFVS spectra at charged interfaces [Neipert, C.; Space, B. J. Chem. Phys. 2006, 125, 224706], and a hyperpolarizability model for water was developed as a prerequisite to practical implementation [Neipert, C.; Space, B. Comput. Lett. 2007, 3, 431-440]. Here, these methods are applied to a highly abstracted/idealized silica/water interface, and the results are compared to experimental data for water at a fused quartz surface. The results suggest that such spectra have some quite general spectral features.}, number={29}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Green, Anthony J. and Space, Brian}, year={2015}, month={Dec}, pages={9219–9224} }
 @article{pham_forrest_hogan_tudor_mclaughlin_belof_eckert_space_2015, title={Understanding Hydrogen Sorption in In-soc-MOF: A Charged Metal-Organic Framework with Open-Metal Sites, Narrow Channels, and Counterions}, volume={15}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/cg5018104}, DOI={10.1021/cg5018104}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations of hydrogen sorption were performed in In-soc-MOF, a charged metal–organic framework (MOF) that contains In3O trimers coordinated to 5,5′-azobis(1,3-benzenedicarboxylate) linkers. The MOF contains nitrate counterions that are located in carcerand-like capsules of the framework. This MOF was shown to have a high hydrogen uptake at 77 K and 1.0 atm. The simulations were performed with a potential that includes explicit many-body polarization interactions, which were important for modeling gas sorption in a charged/polar MOF such as In-soc-MOF. The simulated hydrogen sorption isotherms were in good agreement with experiment in this challenging platform for modeling. The simulations predict a high initial isosteric heat of adsorption, Qst, value of about 8.5 kJ mol–1, which is in contrast to the experimental value of 6.5 kJ mol–1 for all loadings. The difference in the Qst behavior between experiment and simulation is attributed to the fact that, in experimental ...}, number={3}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Hogan, Adam and Tudor, Brant and McLaughlin, Keith and Belof, Jonathan L. and Eckert, Juergen and Space, Brian}, year={2015}, month={Feb}, pages={1460–1471} }
 @article{pham_forrest_banerjee_orcajo_eckert_space_2015, title={Understanding the H2Sorption Trends in the M-MOF-74 Series (M = Mg, Ni, Co, Zn)}, volume={119}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp510253m}, DOI={10.1021/jp510253m}, abstractNote={Electronic structure calculations and simulations of H2 sorption were performed in four members of the M-MOF-74 series: Mg-MOF-74, Ni-MOF-74, Co-MOF-74, and Zn-MOF-74. Notable differences were observed in the partial charge and polarizability of the metal ions derived from the electronic structure calculations. The modeling parameters obtained from the electronic structure calculations were found to influence certain features in the experimentally observed H2 sorption trends in the M-MOF-74 series. The simulations were performed with the inclusion of explicit many-body polarization, which was required to reproduce the experimental H2 sorption observables (i.e., sorption isotherms and isosteric heats of adsorption (Qst)) and the H2–metal interaction in all four MOFs using classical molecular simulation. Consistent with experimental measurements, the simulations captured the following trend for the H2–metal interaction strength: Ni-MOF-74 > Co-MOF-74 > Mg-MOF-74 > Zn-MOF-74. The calculations revealed that s...}, number={2}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Banerjee, Rahul and Orcajo, Gisela and Eckert, Juergen and Space, Brian}, year={2015}, month={Dec}, pages={1078–1090} }
 @article{pham_forrest_georgiev_lohstroh_xue_hogan_eddaoudi_space_eckert_2014, title={A high rotational barrier for physisorbed hydrogen in an fcu-metal–organic framework}, volume={50}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c4cc05987e}, DOI={10.1039/c4cc05987e}, abstractNote={A combined inelastic neutron scattering (INS) and theoretical study of H2 sorption in Y-FTZB, a recently reported metal-organic framework (MOF) with fcu topology, reveals that the strongest binding site in the MOF causes a high barrier to rotation on the sorbed H2. This rotational barrier for H2 is the highest yet of reported MOF materials based on physisorption.}, number={91}, journal={Chem. Commun.}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Georgiev, Peter A. and Lohstroh, Wiebke and Xue, Dong-Xu and Hogan, Adam and Eddaoudi, Mohamed and Space, Brian and Eckert, Juergen}, year={2014}, month={Oct}, pages={14109–14112} }
 @article{pham_forrest_mclaughlin_eckert_space_2014, title={Capturing the H2–Metal Interaction in Mg-MOF-74 Using Classical Polarization}, volume={118}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp508249c}, DOI={10.1021/jp508249c}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations of H2 sorption were performed in Mg-MOF-74, a metal–organic framework (MOF) that displays very high H2 sorption affinity. Experimental H2 sorption isotherms and isosteric heats of adsorption (Qst) values were reproduced using a general purpose materials sorption potential that includes many-body polarization interactions. In contrast, using two models that include only charge–quadrupole interactions failed to reproduce such experimental measurements even though they are the type normally employed in such classical force field calculations. Utilizing the present explicit polarizable model in GCMC simulation resulted in a Mg2+–H2 distance of 2.60 A, which is close to a previously reported value that was obtained using electronic structure methods and comparable to similar experimental measurements. The induced dipole distribution obtained from simulation assisted in the characterization of two previously identified sorption sites in the MOF: the Mg2+ ions and t...}, number={39}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and McLaughlin, Keith and Eckert, Juergen and Space, Brian}, year={2014}, month={Sep}, pages={22683–22690} }
 @article{nugent_pham_mclaughlin_georgiev_lohstroh_embs_zaworotko_space_eckert_2014, title={Dramatic effect of pore size reduction on the dynamics of hydrogen adsorbed in metal–organic materials}, volume={2}, ISSN={2050-7488 2050-7496}, url={http://dx.doi.org/10.1039/c4ta02171a}, DOI={10.1039/c4ta02171a}, abstractNote={The effects of pore size reduction on the dynamics of hydrogen sorption in metal–organic materials (MOMs) were elucidated by studying SIFSIX-2-Cu and its doubly interpenetrated polymorph SIFSIX-2-Cu-i by means of sorption, inelastic neutron scattering (INS), and computational modeling. SIFSIX-2-Cu-i exhibits much smaller pore sizes, which possess high H2 sorption affinity at low loadings. Experimental H2 sorption measurements revealed that the isosteric heat of adsorption (Qst) for H2 in SIFSIX-2-Cu-i is nearly two times higher than that for SIFSIX-2-Cu (8.6 vs. 4.6 kJ mol−1). The INS spectrum for H2 in SIFSIX-2-Cu-i is rather unique for a porous material, as only one broad peak appears at low energies near 6 meV, which simply increases in intensity with loading until the pores are filled. The value for this rotational transition is lower than that in most neutral metal–organic frameworks (MOFs), including those with open Cu sites (8–9 meV), which is indicative of a higher barrier to rotation and stronger interaction in the channels of SIFSIX-2-Cu-i than the open Cu sites in MOFs. Simulations of H2 sorption in SIFSIX-2-Cu-i revealed two hydrogen sorption sites in the MOM: direct interaction with the equatorial fluorine atom (site 1) and between two equatorial fluorine atoms on opposite walls (site 2). The calculated rotational energy levels and rotational barriers for the two sites in SIFSIX-2-Cu-i are in good agreement with INS data. Furthermore, the rotational barriers and binding energies for site 2 are slightly higher than that for site 1, which is consistent with INS results. The lowest calculated transition for the primary site in SIFSIX-2-Cu is also in good agreement with INS data. In addition, this transition in the non-interpenetrating material is higher than any of the sites in SIFSIX-2-Cu-i, which indicates a significantly weaker interaction with the host as a result of the larger pore size.}, number={34}, journal={Journal of Materials Chemistry A}, publisher={Royal Society of Chemistry (RSC)}, author={Nugent, Patrick and Pham, Tony and McLaughlin, Keith and Georgiev, Peter A. and Lohstroh, Wiebke and Embs, Jan Peter and Zaworotko, Michael J. and Space, Brian and Eckert, Juergen}, year={2014}, month={Jul}, pages={13884} }
 @article{forrest_pham_mclaughlin_hogan_space_2014, title={Insights into an intriguing gas sorption mechanism in a polar metal–organic framework with open-metal sites and narrow channels}, volume={50}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c4cc03070b}, DOI={10.1039/c4cc03070b}, abstractNote={Simulations of H2 and CO2 sorption were performed in the metal-organic framework (MOF), [Cu(Me-4py-trz-ia)]. This MOF was recently shown experimentally to exhibit high uptake for H2 and CO2 sorption and this was reproduced and elucidated through the simulations performed herein. Consistent with experiment, the theoretical isosteric heat of adsorption, Q(st), values were nearly constant across all loadings for both sorbates. The simulations revealed that sorption directly onto the open-metal sites was not observed in this MOF, ostensibly a consequence of the low partial positive charges of the Cu(2+) ions as determined through electronic structure calculations. Sorption was primarily observed between adjacent carboxylate oxygen atoms (site 1) and between nearby methyl groups (site 2) of the organic linkers. In addition, saturation of the most energetically favorable sites (site 1) is possible only after filling a nearby site (site 2) first due to the MOF topology. This suggests that the lack of dependence on loading for the Q(st) is due to the concurrent filling of sites 1 and 2, leading to an observed average Q(st) value.}, number={55}, journal={Chem. Commun.}, publisher={Royal Society of Chemistry (RSC)}, author={Forrest, Katherine A. and Pham, Tony and McLaughlin, Keith and Hogan, Adam and Space, Brian}, year={2014}, pages={7283–7286} }
 @article{li_zhang_krishna_yao_han_wu_ma_shi_pham_space_et al._2014, title={Introduction of π-Complexation into Porous Aromatic Framework for Highly Selective Adsorption of Ethylene over Ethane}, volume={136}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja502119z}, DOI={10.1021/ja502119z}, abstractNote={In this work, we demonstrate for the first time the introduction of π-complexation into a porous aromatic framework (PAF), affording significant increase in ethylene uptake capacity, as illustrated in the context of Ag(I) ion functionalized PAF-1, PAF-1-SO3Ag. IAST calculations using single-component-isotherm data and an equimolar ethylene/ethane ratio at 296 K reveal that PAF-1-SO3Ag shows exceptionally high ethylene/ethane adsorption selectivity (Sads: 27 to 125), far surpassing benchmark zeolite and any other MOF reported in literature. The formation of π-complexation between ethylene molecules and Ag(I) ions in PAF-1-SO3Ag has been evidenced by the high isosteric heats of adsorption of C2H4 and also proved by in situ IR spectroscopy studies. Transient breakthrough experiments, supported by simulations, indicate the feasibility of PAF-1-SO3Ag for producing 99.95%+ pure C2H4 in a Pressure Swing Adsorption operation. Our work herein thus suggests a new perspective to functionalizing PAFs and other types of advanced porous materials for highly selective adsorption of ethylene over ethane.}, number={24}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Li, Baiyan and Zhang, Yiming and Krishna, Rajamani and Yao, Kexin and Han, Yu and Wu, Zili and Ma, Dingxuan and Shi, Zhan and Pham, Tony and Space, Brian and et al.}, year={2014}, month={Jun}, pages={8654–8660} }
 @article{pham_forrest_mcdonald_space_2014, title={Modeling PCN-61 and PCN-66: Isostructural rht-Metal–Organic Frameworks with Distinct CO2 Sorption Mechanisms}, volume={14}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/cg500860t}, DOI={10.1021/cg500860t}, abstractNote={Simulations of CO2 sorption were performed in two members of the highly tunable rht-metal–organic framework (MOF) platform: PCN-61 and PCN-66. These MOFs differ only in the triisophthalate ligand used to synthesize the respective MOFs. In PCN-61, the center of the ligand contains a benzene ring; this ring is substituted with a triphenylamine group in PCN-66. There are two chemically distinct Cu2+ ions that comprise the copper paddlewheels, [Cu2(O2CR)4], in all rht-MOFs. One type of Cu2+ ion, denoted Cu1, projects into the truncated tetrahedral (T–Td) and truncated octahedral (T–Oh) cages, while the other Cu2+ ion, denoted Cu2, projects into the cuboctahedral (cub–Oh) cages. Electronic structure calculations revealed that, in PCN-61, the Cu2 ions have a significantly higher partial positive charge than the Cu1 ions, whereas the opposite was observed in PCN-66. The simulations revealed that the CO2 molecules sorb initially onto the Cu2+ ions that have the higher partial positive charge, i.e., the Cu2 ions i...}, number={11}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and McDonald, Kyle and Space, Brian}, year={2014}, month={Oct}, pages={5599–5607} }
 @article{elsaidi_mohamed_wojtas_chanthapally_pham_space_vittal_zaworotko_2014, title={Putting the Squeeze on CH4 and CO2 through Control over Interpenetration in Diamondoid Nets}, volume={136}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja500005k}, DOI={10.1021/ja500005k}, abstractNote={We report the synthesis, structure, and sorption properties of a family of eight diamondoid (dia) metal-organic materials (MOMs) that are sustained by Co(II) or Zn(II) cations linked by one of three rigid ligands: 4-(2-(4-pyridyl)ethenyl)benzoate (1), 4-(pyridin-4-yl)benzoate (2), and 4-(pyridin-4-yl)acrylate (3). Pore size control in this family of dia nets was exerted by two approaches: changing the length of the linker ligand from 1 to 3, and using solvent as a template to control the level of interpenetration in nets based upon 1 and 3. The resulting MOMs, dia-8i-1, dia-5i-3, dia-7i-1-Zn, dia-7i-1-Co, dia-4i-3-a, dia-4i-3-b, dia-4i-2, and dia-4i-1, exhibit 1D channels with pore limiting diameters (PLDs) of 1.64, 2.90, 5.06, 5.28, 8.57, 8.83, 11.86, and 18.25 Å, respectively. We selected dia nets for this study for the following reasons: their 1D channels facilitate study of the impact of pore size on gas sorption parameters in situations where pore chemistry is similar (pyridyl benzoate-type linkers) or identical (in the case of polymorphs), and their saturated metal centers eliminate open metal sites from dominating sorbent-solvate interactions and possibly masking the effect of pore size. Our data reveal that smaller pore sizes offer stronger interactions, as determined by the isosteric heat of adsorption (Qst) and the steepness of the adsorption isotherm in the low-pressure region. The porous MOM with the smallest PLD suitable for physisorption, dia-7i-1-Co, was thereby found to exhibit the highest Qst values for CO2 and CH4. Indeed, dia-7i-1-Co exhibits a Qst for CH4 of 26.7 kJ/mol, which was validated through grand canonical Monte Carlo simulation studies of CH4 adsorption. This Qst value is considerably higher than those found in covalent organic frameworks and other MOMs with unsaturated metal centers. These results therefore further validate the critical role that PLD plays in gas adsorption by porous MOMs.}, number={13}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Elsaidi, Sameh K. and Mohamed, Mona H. and Wojtas, Lukasz and Chanthapally, Anjana and Pham, Tony and Space, Brian and Vittal, Jagadese J. and Zaworotko, Michael J.}, year={2014}, month={Mar}, pages={5072–5077} }
 @article{pham_forrest_hogan_mclaughlin_belof_eckert_space_2014, title={Simulations of hydrogen sorption in rht-MOF-1: identifying the binding sites through explicit polarization and quantum rotation calculations}, volume={2}, ISSN={2050-7488 2050-7496}, url={http://dx.doi.org/10.1039/c3ta14591c}, DOI={10.1039/c3ta14591c}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations of hydrogen sorption were performed in rht-MOF-1, a metal–organic framework (MOF) that consists of isophthalate groups joined by copper paddlewheel clusters and Cu3O trimers through tetrazolate moeities. This is a charged rht-MOF that contains extra-framework nitrate counterions within the material. For the simulations performed herein, excellent agreement with experiment was achieved for the simulated hydrogen sorption isotherms and calculated isosteric heat of adsorption, Qst, values only when using a polarizable potential. Thermodynamic agreement is demonstrated via comparing to experimental isotherms and binding sites are revealed by combining simulation and inelastic neutron scattering (INS) data. Simulations involving explicit many-body polarization interactions assisted in the determination of the binding sites in rht-MOF-1 through the distribution of the induced dipoles that led to strong adsorbate interactions. Four distinct hydrogen sorption sites were determined from the polarization distribution: the nitrate ions located in the corners of the truncated tetrahedral cages, the Cu2+ ions of the paddlewheels that project into the truncated tetrahedral and truncated octahedral cages (Cu1 ions), the Cu2+ ions of the Cu3O trimers (Cu3 ions), and the sides of the paddlewheels in the cuboctahedral cage. The simulations revealed that the initial sorption sites for hydrogen in rht-MOF-1 are the nitrate ions; this site corresponds to the high initial Qst value for hydrogen (9.5 kJ mol−1) in the MOF. The radial distribution functions, g(r), about the Cu2+ ions at various loadings revealed that the Cu1 ions are the preferred open-metal sorption sites for hydrogen at low loading, while the Cu3 ions become occupied at higher loadings. The validation of the aforementioned sorption sites in rht-MOF-1 was confirmed by calculating the two-dimensional quantum rotational levels about each site and comparing the levels to the transitions that were observed in the experimental INS spectra for hydrogen in the compound. For each binding site, the rotational transitions from j = 0 to j = 1 were in good agreement to certain transitions that were observed in the INS spectra. From these calculations, the assignment of the peaks in the INS spectra for hydrogen in rht-MOF-1 has been made.}, number={7}, journal={J. Mater. Chem. A}, publisher={Royal Society of Chemistry (RSC)}, author={Pham, Tony and Forrest, Katherine A. and Hogan, Adam and McLaughlin, Keith and Belof, Jonathan L. and Eckert, Juergen and Space, Brian}, year={2014}, pages={2088–2100} }
 @article{pham_forrest_tudor_elsaidi_mohamed_mclaughlin_cioce_zaworotko_space_2014, title={Theoretical Investigations of CO2 and CH4 Sorption in an Interpenetrated Diamondoid Metal–Organic Material}, volume={30}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/la500967w}, DOI={10.1021/la500967w}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations of CO2 and CH4 sorption and separation were performed in dia-7i-1-Co, a metal–organic material (MOM) consisting of a 7-fold interpenetrated net of Co2+ ions coordinated to 4-(2-(4-pyridyl)ethenyl)benzoate linkers. This MOM shows high affinity toward CH4 at low loading due to the presence of narrow, close fitting, one-dimensional hydrophobic channels—this makes the MOM relevant for applications in low-pressure methane storage. The calculated CO2 and CH4 sorption isotherms and isosteric heat of adsorption, Qst, values in dia-7i-1-Co are in good agreement with the corresponding experimental results for all state points considered. The experimental initial Qst value for CH4 in dia-7i-1-Co is currently the highest of reported MOM materials, and this was further validated by the simulations performed herein. The simulations predict relatively constant Qst values for CO2 and CH4 sorption across all loadings in dia-7i-1-Co, consistent with the one type of binding site identified for the respective sorbate molecules in this MOM. Examination of the three-dimensional histogram showing the sites of CO2 and CH4 sorption in dia-7i-1-Co confirmed this finding. Inspection of the modeled structure revealed that the sorbate molecules form a strong interaction with the organic linkers within the constricted hydrophobic channels. Ideal adsorbed solution theory (IAST) calculations and GCMC binary mixture simulations predict that the selectivity of CO2 over CH4 in dia-7i-1-Co is quite low, which is a direct consequence of the MOM’s high affinity toward both CO2 and CH4 as well as the nonspecific mechanism shown here. This study provides theoretical insights into the effects of pore size on CO2 and CH4 sorption in porous MOMs and its effect upon selectivity, including postulating design strategies to distinguish between sorbates of similar size and hydrophobicity.}, number={22}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Tudor, Brant and Elsaidi, Sameh K. and Mohamed, Mona H. and McLaughlin, Keith and Cioce, Christian R. and Zaworotko, Michael J. and Space, Brian}, year={2014}, month={May}, pages={6454–6462} }
 @article{mullen_pham_forrest_cioce_mclaughlin_space_2013, title={A Polarizable and Transferable PHAST CO2 Potential for Materials Simulation}, volume={9}, ISSN={1549-9618 1549-9626}, url={http://dx.doi.org/10.1021/ct400549q}, DOI={10.1021/ct400549q}, abstractNote={Reliable PHAST (Potentials with High Accuracy Speed and Transferability) intermolecular potential energy functions for CO2 have been developed from first principles for use in heterogeneous systems, including one with explicit polarization. The intermolecular potentials have been expressed in a transferable form and parametrized from nearly exact electronic structure calculations. Models with and without explicit many-body polarization effects, known to be important in simulation of interfacial processes, are constructed. The models have been validated on pressure-density isotherms of bulk CO2 and adsorption in three metal-organic framework (MOF) materials. The present models appear to offer advantages over high quality fluid/liquid state potentials in describing CO2 interactions in interfacial environments where sorbates adopt orientations not commonly explored in bulk fluids. Thus, the nonpolar CO2-PHAST and polarizable CO2-PHAST* potentials are recommended for materials/interfacial simulations.}, number={12}, journal={Journal of Chemical Theory and Computation}, publisher={American Chemical Society (ACS)}, author={Mullen, Ashley L. and Pham, Tony and Forrest, Katherine A. and Cioce, Christian R. and McLaughlin, Keith and Space, Brian}, year={2013}, month={Nov}, pages={5421–5429} }
 @article{cioce_mclaughlin_belof_space_2013, title={A Polarizable and Transferable PHAST N2Potential for Use in Materials Simulation}, volume={9}, ISSN={1549-9618 1549-9626}, url={http://dx.doi.org/10.1021/ct400526a}, DOI={10.1021/ct400526a}, abstractNote={A polarizable and transferable intermolecular potential energy function, potentials with high accuracy, speed, and transferability (PHAST), has been developed from first principles for molecular nitrogen to be used in the modeling of heterogeneous processes such as materials sorption and separations. A five-site (van der Waals and point charge) anisotropic model, that includes many-body polarization, is proposed. It is parametrized to reproduce high-level electronic structure calculations (CCSD(T) using Dunning-type basis sets extrapolated to the CBS limit) for a representative set of dimer potential energy curves. Thus it provides a relatively simple yet robust and broadly applicable representation of nitrogen. Two versions are developed, differing by the type of mixing rules applied to unlike Lennard-Jones potential sites. It is shown that the Waldman-Hagler mixing rules are more accurate than Lorentz-Berthelot. The resulting potentials are demonstrated to be effective in modeling neat nitrogen but are designed to also be useful in modeling N2 interactions in a large array of environments such as metal-organic frameworks and zeolites and at interfaces. In such settings, capturing anisotropic forces and interactions with (open and coordinated) metals and charged/polar environments is essential. In developing the potential, it was found that adding a seemingly redundant dimer orientation, slip-parallel (S), improved the transferability of the potential energy surface (PES). Notably, one of the solid phases of nitrogen was not as accurately represented energetically without including S in the representative set. Liquid simulations, however, were unaffected and worked equally well for both potentials. This suggests that accounting for a wide variety of configurations is critical in designing a potential that is intended for use in heterogeneous environments where many orientations, including those not commonly explored in the bulk, are possible. Testing and validation of the potential are achieved via simulations of a thermal distribution of trimer geometries compared to analogous high level electronic structure calculations and molecular simulations of bulk pressure-density isotherms across the vapor, supercritical, and liquid phases. Crystal lattice parameters and energetics of the α-N2 and γ-N2 solid phases are also evaluated and determined to be in good agreement with experiment. Thus the proposed potential is shown to be efficacious for gas, liquid, and solid use, representing both disordered and ordered configurations.}, number={12}, journal={Journal of Chemical Theory and Computation}, publisher={American Chemical Society (ACS)}, author={Cioce, Christian R. and McLaughlin, Keith and Belof, Jonathan L. and Space, Brian}, year={2013}, month={Nov}, pages={5550–5557} }
 @article{nugent_rhodus_pham_forrest_wojtas_space_zaworotko_2013, title={A Robust Molecular Porous Material with High CO2 Uptake and Selectivity}, volume={135}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja4054948}, DOI={10.1021/ja4054948}, abstractNote={We report MPM-1-TIFSIX, a molecular porous material (MPM) based upon the neutral metal complex [Cu2(adenine)4(TiF6)2], that self-assembles through a hydrogen-bonding network. This MPM is amenable to room-temperature synthesis and activation. Gas adsorption measurements and ideal adsorbed solution theory selectivity predictions at 298 K revealed enhanced CO2 separation performance relative to a previously known variant as well as the highest CO2 uptake and isosteric heat of adsorption yet reported for an MPM. MPM-1-TIFSIX is thermally stable to 568 K and retains porosity and capacity even after immersion in water for 24 h.}, number={30}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Nugent, Patrick S. and Rhodus, Vanessah Lou and Pham, Tony and Forrest, Katherine and Wojtas, Lukasz and Space, Brian and Zaworotko, Michael J.}, year={2013}, month={Jul}, pages={10950–10953} }
 @article{forrest_pham_hogan_mclaughlin_tudor_nugent_burd_mullen_cioce_wojtas_et al._2013, title={Computational Studies of CO2Sorption and Separation in an Ultramicroporous Metal–Organic Material}, volume={117}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp405781c}, DOI={10.1021/jp405781c}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations of CO2 sorption and separation were performed in [Zn(pyz)2SiF6], a metal–organic material (MOM) consisting of a square grid of Zn2+ ions coordinated to pyrazine (pyz) linkers and pillars of SiF62– ions. This MOM was recently shown to have an unprecedented selectivity for CO2 over N2, CH4, and H2 under industrially relevant conditions. The simulated CO2 sorption isotherms and calculated isosteric heat of adsorption, Qst, values were in excellent agreement with the experimental data for all the state points considered. CO2 saturation in [Zn(pyz)2SiF6] was achieved at near-ambient temperatures and pressures lower than 1.0 atm. Moreover, the sorbed CO2 molecules were representative of a liquid/fluid under such conditions as confirmed through calculating the isothermal compressibility, βT, values. The simulated CO2 uptakes within CO2/N2 (10:90), CO2/CH4 (50:50), and CO2/H2 (30:70) mixture compositions, characteristic of flue gas, biogas, and syngas, respectively, ...}, number={34}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Forrest, Katherine A. and Pham, Tony and Hogan, Adam and McLaughlin, Keith and Tudor, Brant and Nugent, Patrick and Burd, Stephen D. and Mullen, Ashley and Cioce, Christian R. and Wojtas, Lukasz and et al.}, year={2013}, month={Aug}, pages={17687–17698} }
 @article{mclaughlin_cioce_pham_belof_space_2013, title={Efficient calculation of many-body induced electrostatics in molecular systems}, volume={139}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.4829144}, DOI={10.1063/1.4829144}, abstractNote={Potential energy functions including many-body polarization are in widespread use in simulations of aqueous and biological systems, metal-organics, molecular clusters, and other systems where electronically induced redistribution of charge among local atomic sites is of importance. The polarization interactions, treated here via the methods of Thole and Applequist, while long-ranged, can be computed for moderate-sized periodic systems with extremely high accuracy by extending Ewald summation to the induced fields as demonstrated by Nymand, Sala, and others. These full Ewald polarization calculations, however, are expensive and often limited to very small systems, particularly in Monte Carlo simulations, which may require energy evaluation over several hundred-thousand configurations. For such situations, it shall be shown that sufficiently accurate computation of the polarization energy can be produced in a fraction of the central processing unit (CPU) time by neglecting the long-range extension to the induced fields while applying the long-range treatments of Ewald or Wolf to the static fields; these methods, denoted Ewald E-Static and Wolf E-Static (WES), respectively, provide an effective means to obtain polarization energies for intermediate and large systems including those with several thousand polarizable sites in a fraction of the CPU time. Furthermore, we shall demonstrate a means to optimize the damping for WES calculations via extrapolation from smaller trial systems.}, number={18}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={McLaughlin, Keith and Cioce, Christian R. and Pham, Tony and Belof, Jonathan L. and Space, Brian}, year={2013}, month={Nov}, pages={184112} }
 @article{nugent_rhodus_pham_tudor_forrest_wojtas_space_zaworotko_2013, title={Enhancement of CO2 selectivity in a pillared pcu MOM platform through pillar substitution}, volume={49}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c3cc37695h}, DOI={10.1039/c3cc37695h}, abstractNote={Pillar substitution in a long-known metal-organic material with saturated metal centres, [Cu(bipy)(2)(SiF(6))](n), has afforded the first crystallographically characterized porous materials based upon TiF(6)(2-) and SnF(6)(2-) anions as pillars. Gas adsorption studies revealed similar surface areas and adsorption isotherms but enhanced selectivity towards CO(2)vs. CH(4) and N(2).}, number={16}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Nugent, Patrick and Rhodus, Vanessah and Pham, Tony and Tudor, Brant and Forrest, Katherine and Wojtas, Lukasz and Space, Brian and Zaworotko, Michael}, year={2013}, pages={1606} }
 @article{forrest_pham_nugent_burd_mullen_wojtas_zaworotko_space_2013, title={Examining the Effects of Different Ring Configurations and Equatorial Fluorine Atom Positions on CO2Sorption in [Cu(bpy)2SiF6]}, volume={13}, ISSN={1528-7483 1528-7505}, url={http://dx.doi.org/10.1021/cg401034s}, DOI={10.1021/cg401034s}, abstractNote={Simulations of CO2 sorption were performed in a metal–organic material (MOM) that is part of a “SIFSIX” family of compounds that has remarkable carbon dioxide capture and separation properties. The MOM considered here has the formula [Cu(bpy)2SiF6] (bpy = 4,4′-bipyridine). This hydrophobic MOM is both water-stable and CO2-specific with significant sorption capacity under ambient conditions. The crystal structure reveals bpy rings and equatorial fluorine atoms in multiple possible orientations; the static disorder has been modeled based on single-crystal X-ray diffraction data revealing several possible relatives of atoms in the crystal structure. With regards to the bpy rings, the structure can be interpreted as two pyridyl rings with coplanar configurations within a unit cell (configuration 1), a twisted bpy ring conformation in which orthogonal pyridyl rings have C4 symmetry about the Cu2+ ion (configuration 2), and a twisted bpy ring conformation in which the two orthogonal pyridyl rings are facing one...}, number={10}, journal={Crystal Growth & Design}, publisher={American Chemical Society (ACS)}, author={Forrest, Katherine A. and Pham, Tony and Nugent, Patrick and Burd, Stephen D. and Mullen, Ashley and Wojtas, Lukasz and Zaworotko, Michael J. and Space, Brian}, year={2013}, month={Sep}, pages={4542–4548} }
 @article{pham_forrest_eckert_georgiev_mullen_luebke_cairns_belmabkhout_eubank_mclaughlin_et al._2013, title={Investigating the Gas Sorption Mechanism in an rht-Metal–Organic Framework through Computational Studies}, volume={118}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp409950r}, DOI={10.1021/jp409950r}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations were performed to investigate CO2 and H2 sorption in an rht-metal–organic framework (MOF) that was synthesized with a ligand having a nitrogen-rich trigonal core through trisubstituted triazine groups and amine functional groups. This MOF was synthesized by two different groups, each reporting their own distinct gas sorption measurements and crystal structure. Electronic structure calculations demonstrated that the small differences in the atomic positions between each group’s crystal structure resulted in different electrostatic parameters about the Cu2+ ions for the respective unit cells. Simulations of CO2 sorption were performed with and without many-body polarization effects and using our recently developed CO2 potentials, in addition to a well-known bulk CO2 model, in both crystallographic unit cells. Simulated CO2 sorption isotherms and calculated isosteric heats of adsorption, Qst, values were in excellent agreement with the results reported previousl...}, number={1}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Eckert, Juergen and Georgiev, Peter A. and Mullen, Ashley and Luebke, Ryan and Cairns, Amy J. and Belmabkhout, Youssef and Eubank, Jarrod F. and McLaughlin, Keith and et al.}, year={2013}, month={Dec}, pages={439–456} }
 @article{mohamed_elsaidi_pham_forrest_tudor_wojtas_space_zaworotko_2013, title={Pillar substitution modulates CO2 affinity in “mmo” topology networks}, volume={49}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/c3cc44745f}, DOI={10.1039/c3cc44745f}, abstractNote={The use of WO4(2-) instead of CrO4(2-) or MoO4(2-) as an angular pillar in topology nets has afforded two isostructural porous nets of formula [M(bpe)2WO4] (M = Co or Ni, bpe = 1,2-(4-pyridyl)ethene). The Ni variant, WOFOUR-1-Ni, is highly selective towards CO2 thanks to its exceptionally high isosteric heat of adsorption (Qst) of -65.5 kJ mol(-1) at zero loading.}, number={84}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Mohamed, Mona H. and Elsaidi, Sameh K. and Pham, Tony and Forrest, Katherine A. and Tudor, Brant and Wojtas, Lukasz and Space, Brian and Zaworotko, Michael J.}, year={2013}, pages={9809} }
 @article{nugent_belmabkhout_burd_cairns_luebke_forrest_pham_ma_space_wojtas_et al._2013, title={Porous materials with optimal adsorption thermodynamics and kinetics for CO2 separation}, volume={495}, ISSN={0028-0836 1476-4687}, url={http://dx.doi.org/10.1038/nature11893}, DOI={10.1038/nature11893}, abstractNote={The energy costs associated with the separation and purification of industrial commodities, such as gases, fine chemicals and fresh water, currently represent around 15 per cent of global energy production, and the demand for such commodities is projected to triple by 2050 (ref. 1). The challenge of developing effective separation and purification technologies that have much smaller energy footprints is greater for carbon dioxide (CO2) than for other gases; in addition to its involvement in climate change, CO2 is an impurity in natural gas, biogas (natural gas produced from biomass), syngas (CO/H2, the main source of hydrogen in refineries) and many other gas streams. In the context of porous crystalline materials that can exploit both equilibrium and kinetic selectivity, size selectivity and targeted molecular recognition are attractive characteristics for CO2 separation and capture, as exemplified by zeolites 5A and 13X (ref. 2), as well as metal-organic materials (MOMs). Here we report that a crystal engineering or reticular chemistry strategy that controls pore functionality and size in a series of MOMs with coordinately saturated metal centres and periodically arrayed hexafluorosilicate (SiF(2-)(6)) anions enables a 'sweet spot' of kinetics and thermodynamics that offers high volumetric uptake at low CO2 partial pressure (less than 0.15 bar). Most importantly, such MOMs offer an unprecedented CO2 sorption selectivity over N2, H2 and CH4, even in the presence of moisture. These MOMs are therefore relevant to CO2 separation in the context of post-combustion (flue gas, CO2/N2), pre-combustion (shifted synthesis gas stream, CO2/H2) and natural gas upgrading (natural gas clean-up, CO2/CH4).}, number={7439}, journal={Nature}, publisher={Springer Science and Business Media LLC}, author={Nugent, Patrick and Belmabkhout, Youssef and Burd, Stephen D. and Cairns, Amy J. and Luebke, Ryan and Forrest, Katherine and Pham, Tony and Ma, Shengqian and Space, Brian and Wojtas, Lukasz and et al.}, year={2013}, month={Feb}, pages={80–84} }
 @article{tudor_space_2013, title={Solving the Many-Body Polarization Problem on GPUs: Application to MOFs}, volume={4}, ISSN={2153-4136}, url={http://dx.doi.org/10.22369/issn.2153-4136/4/1/5}, DOI={10.22369/issn.2153-4136/4/1/5}, abstractNote={Massively Parallel Monte Carlo, an in-house computer code available at http://code.google.com/p/mpmc/,has been successfully utilized to simulate interactions between gas phase sorbates and various metal-organic materials.In this regard, calculations involving polarizability were found to be critical, and computationally expensive.Although GPGPU routines have increased the speed of these calculations immensely, in its original state, the program was only able to leverage a GPU's power on small systems.In order to study larger and evermore complex systems, the program model was modified such that limitations related to system size were relaxed while performance was either increased or maintained.In this project, parallel programming techniques learned from the Blue Waters Undergraduate Petascale Education Program were employed to increase the efficiency and expand the utility of this code.}, number={1}, journal={The Journal of Computational Science Education}, publisher={The Shodor Education Foundation, Inc.}, author={Tudor, Brant and Space, Brian}, year={2013}, month={Nov}, pages={30–34} }
 @article{pham_forrest_mclaughlin_tudor_nugent_hogan_mullen_cioce_zaworotko_space_2013, title={Theoretical Investigations of CO2and H2Sorption in an Interpenetrated Square-Pillared Metal–Organic Material}, volume={117}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp402764s}, DOI={10.1021/jp402764s}, abstractNote={Simulations of CO2 and H2 sorption and separation were performed in [Cu(dpa)2SiF6-i], a metal–organic material (MOM) consisting of an interpenetrated square grid of Cu2+ ions coordinated to 4,4′-dipyridylacetylene (dpa) rings and pillars of SiF62– ions. This class of water stable MOMs shows great promise in practical gas sorption/separation with especially high selectivity for CO2 and variable selectivity for other energy related gases. Simulated CO2 sorption isotherms and isosteric heats of adsorption, Qst, at ambient temperatures were in excellent agreement with the experimental measurements at all pressures considered. Further, it was observed that the Qst for CO2 increases as a function of uptake in [Cu(dpa)2SiF6-i]. This suggests that nascently sorbed CO2 molecules within a channel contribute to a more energetically favorable site for additional CO2 molecules, i.e., in stark contrast to typical behavior, sorbate intermolecular interactions enhance sorption energetics with increased loading. The simul...}, number={19}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and McLaughlin, Keith and Tudor, Brant and Nugent, Patrick and Hogan, Adam and Mullen, Ashley and Cioce, Christian R. and Zaworotko, Michael J. and Space, Brian}, year={2013}, month={May}, pages={9970–9982} }
 @article{pham_forrest_nugent_belmabkhout_luebke_eddaoudi_zaworotko_space_2013, title={Understanding Hydrogen Sorption in a Metal–Organic Framework with Open-Metal Sites and Amide Functional Groups}, volume={117}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp402304a}, DOI={10.1021/jp402304a}, abstractNote={Grand canonical Monte Carlo (GCMC) studies of the mechanism of hydrogen sorption in an rht-MOF known as Cu-TPBTM are presented. The MOF is a decorated/substituted isostructural analogue to the unembellished rht-MOF, PCN-61, that was studied previously [Forrest, K. A.J. Phys. Chem. C 2012, 116, 15538−15549.]. The simulations were performed using three different hydrogen potentials of increasing complexity. Simulated hydrogen sorption isotherms and calculated isosteric heat of adsorption, Qst, values were in excellent agreement with the reported experimental data for only a polarizable model in one of four experimentally observed crystal structure configurations. The study demonstrates the ability of modeling to distinguish the differential sorption of distinct strucures; one configuration is found to be dominant due to favorable interactions with substrates. In addition, it was discovered that the presence of polar amide groups had a significant effect on the electrostatics of the Cu2+ ions and directs the...}, number={18}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Pham, Tony and Forrest, Katherine A. and Nugent, Patrick and Belmabkhout, Youssef and Luebke, Ryan and Eddaoudi, Mohamed and Zaworotko, Michael J. and Space, Brian}, year={2013}, month={Apr}, pages={9340–9354} }
 @article{mclaughlin_cioce_belof_space_2012, title={A molecular H2 potential for heterogeneous simulations including polarization and many-body van der Waals interactions}, volume={136}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.4717705}, DOI={10.1063/1.4717705}, abstractNote={A highly accurate aniostropic intermolecular potential for diatomic hydrogen has been developed that is transferable for molecular modeling in heterogeneous systems. The potential surface is designed to be efficacious in modeling mixed sorbates in metal-organic materials that include sorption interactions with charged interfaces and open metal sites. The potential parameters are compatible for mixed simulations but still maintain high accuracy while deriving dispersion parameters from a proven polarizability model. The potential includes essential physical interactions including: short-range repulsions, dispersion, and permanent and induced electrostatics. Many-body polarization is introduced via a point-atomic polarizability model that is also extended to account for many-body van der Waals interactions in a consistent fashion. Permanent electrostatics are incorporated using point partial charges on atomic sites. However, contrary to expectation, the best potentials are obtained by permitting the charges to take on values that do not reproduce the first non-vanishing moment of the electrostatic potential surface, i.e., the quadrupole moment. Potential parameters are fit to match ab initio energies for a representative range of dimer geometries. The resulting potential is shown to be highly effective by comparing to electronic structure calculations for a thermal distribution of trimer geometries, and by reproducing experimental bulk pressure-density isotherms. The surface is shown to be superior to other similarly portable potential choices even in tests on homogeneous systems without strong polarizing fields. The present streamlined approach to developing such potentials allows for a simple adaptation to other molecules amenable to investigation by high-level electronic structure methods.}, number={19}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={McLaughlin, Keith and Cioce, Christian R. and Belof, Jonathan L. and Space, Brian}, year={2012}, month={May}, pages={194302} }
 @article{green_perry_moore_space_2012, title={A theoretical study of the sum frequency vibrational spectroscopy of the carbon tetrachloride/water interface}, volume={24}, ISSN={0953-8984 1361-648X}, url={http://dx.doi.org/10.1088/0953-8984/24/12/124108}, DOI={10.1088/0953-8984/24/12/124108}, abstractNote={Theoretical approximations to the sum frequency vibrational spectroscopy (SFVS) of the carbon tetrachloride/water interface are constructed using the quantum-corrected time correlation functions (TCF) to aid in interpretation of experimental data and to predict novel vibrational modes. Instantaneous normal mode (INM) methods are used to characterize the observed modes leading to the TCF signal, thus providing molecular resolution of the vibrational lineshapes. Detailed comparisons of the theoretical signals are made with those obtained experimentally and show excellent agreement for the spectral peaks in the O–H stretching region of water. An intermolecular mode, unique to the interface, at 848 cm−1 is also identifiable, similar to the one seen for the water/vapor interface. INM analysis reveals the resonance is due to a wagging mode (hindered rotation) that was previously identified (Perry et al 2005 J. Chem. Phys. 123 144705) as localized on a single water molecule with both hydrogens displaced normal to the interface—generally it is found that the symmetry breaking at the interface leads to hindered translations and rotations at hydrophilic/hydrophobic interfaces that assume finite vibrational frequencies due to anchoring at the aqueous interface. Additionally, examination of the real and imaginary parts of the theoretical SFVS spectra reveal the spectroscopic species attributed the resonances and possible subspecies in the O–H region; these results are consistent with extant experimental data and associated analysis.}, number={12}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Green, Anthony J and Perry, Angela and Moore, Preston B and Space, Brian}, year={2012}, month={Mar}, pages={124108} }
 @article{mclaughlin_cioce_belof_space_2012, title={Erratum: “A molecular H2 potential for heterogeneous simulations including polarization and many-body van der Waals interactions” [J. Chem. Phys. 136, 194302 (2012)]}, volume={137}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.4755289}, DOI={10.1063/1.4755289}, abstractNote={First Page}, number={12}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={McLaughlin, Keith and Cioce, Christian R. and Belof, Jonathan L. and Space, Brian}, year={2012}, month={Sep}, pages={129901} }
 @article{mohamed_elsaidi_wojtas_pham_forrest_tudor_space_zaworotko_2012, title={Highly Selective CO2 Uptake in Uninodal 6-Connected “mmo” Nets Based upon MO42– (M = Cr, Mo) Pillars}, volume={134}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja309452y}, DOI={10.1021/ja309452y}, abstractNote={A novel 4(8).6(7) topology metal-organic material (MOM) platform of formula [M(bpe)(2)(M'O(4))] (M = Co or Ni; bpe = 1,2-bis(4-pyridyl)ethene; M' = Mo or Cr) has been synthesized and evaluated in the context of gas sorption. These MOMs have been assigned RCSR code mmo and are uninodal 6-connected nets. [Ni(bpe)(2)(MoO(4))], MOOFOUR-1-Ni, and its chromate analogue, CROFOUR-1-Ni, exhibit high CO(2) affinity and selectivity, especially at low loading. This behavior can be attributed to exceptionally high isosteric heats of adsorption (Q(st)) of CO(2) in MOOFOUR-1-Ni and CROFOUR-1-Ni of ∼56 and ∼50 kJ/mol, respectively, at zero loading. These results were validated by molecular simulations which indicate that the electrostatics of these inorganic anions affords attractions toward CO(2) that are comparable to those of unsaturated metal centers.}, number={48}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Mohamed, Mona H. and Elsaidi, Sameh K. and Wojtas, Lukasz and Pham, Tony and Forrest, Katherine A. and Tudor, Brant and Space, Brian and Zaworotko, Michael J.}, year={2012}, month={Nov}, pages={19556–19559} }
 @article{matanović_belof_space_sillar_sauer_eckert_bačić_2012, title={Hydrogen adsorbed in a metal organic framework-5: Coupled translation-rotation eigenstates from quantum five-dimensional calculations}, volume={137}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.4730906}, DOI={10.1063/1.4730906}, abstractNote={We report rigorous quantum five-dimensional (5D) calculations of the coupled translation-rotation (T-R) eigenstates of a H(2) molecule adsorbed in metal organic framework-5 (MOF-5), a prototypical nanoporous material, which was treated as rigid. The anisotropic interactions between H(2) and MOF-5 were represented by the analytical 5D intermolecular potential energy surface (PES) used previously in the simulations of the thermodynamics of hydrogen sorption in this system [Belof et al., J. Phys. Chem. C 113, 9316 (2009)]. The global and local minima on this 5D PES correspond to all of the known binding sites of H(2) in MOF-5, three of which, α-, β-, and γ-sites are located on the inorganic cluster node of the framework, while two of them, the δ- and ε-sites, are on the phenylene link. In addition, 2D rotational PESs were calculated ab initio for each of these binding sites, keeping the center of mass of H(2) fixed at the respective equilibrium geometries; purely rotational energy levels of H(2) on these 2D PESs were computed by means of quantum 2D calculations. On the 5D PES, the three adjacent γ-sites lie just 1.1 meV above the minimum-energy α-site, and are separated from it by a very low barrier. These features allow extensive wave function delocalization of even the lowest translationally excited T-R eigenstates over the α- and γ-sites, presenting significant challenges for both the quantum bound-state calculations and the analysis of the results. Detailed comparison is made with the available experimental data.}, number={1}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Matanović, Ivana and Belof, Jonathan L. and Space, Brian and Sillar, Kaido and Sauer, Joachim and Eckert, Juergen and Bačić, Zlatko}, year={2012}, month={Jul}, pages={014701} }
 @article{forrest_pham_mclaughlin_belof_stern_zaworotko_space_2012, title={Simulation of the Mechanism of Gas Sorption in a Metal–Organic Framework with Open Metal Sites: Molecular Hydrogen in PCN-61}, volume={116}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp306084t}, DOI={10.1021/jp306084t}, abstractNote={Grand canonical Monte Carlo (GCMC) simulations were performed to investigate hydrogen sorption in an rht-type metal–organic framework (MOF), PCN-61. The MOF was shown to have a large hydrogen uptake, and this was studied using three different hydrogen potentials, effective for bulk hydrogen, but of varying sophistication: a model that includes only repulsion/dispersion parameters, one augmented with charge-quadrupole interactions, and one supplemented with many-body polarization interactions. Calculated hydrogen uptake isotherms and isosteric heats of adsorption, Qst, were in quantitative agreement with experiment only for the model with explicit polarization. This success in reproducing empirical measurements suggests that modeling MOFs that have open metal sites is feasible, though it is often not considered to be well described via a classical potential function; here it is shown that such systems may be accurately described by explicitly including polarization effects in an otherwise traditional empir...}, number={29}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Forrest, Katherine A. and Pham, Tony and McLaughlin, Keith and Belof, Jonathan L. and Stern, Abraham C. and Zaworotko, Michael J. and Space, Brian}, year={2012}, month={Jul}, pages={15538–15549} }
 @article{stern_belof_eddaoudi_space_2012, title={Understanding hydrogen sorption in a polar metal-organic framework with constricted channels}, volume={136}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.3668138}, DOI={10.1063/1.3668138}, abstractNote={A high fidelity molecular model is developed for a metal-organic framework (MOF) with narrow (approximately 7.3 Å) nearly square channels. MOF potential models, both with and neglecting explicit polarization, are constructed. Atomic partial point charges for simulation are derived from both fragment-based and fully periodic electronic structure calculations. The molecular models are designed to accurately predict and retrodict material gas sorption properties while assessing the role of induction for molecular packing in highly restricted spaces. Thus, the MOF is assayed via grand canonical Monte Carlo (GCMC) for its potential in hydrogen storage. The confining channels are found to typically accommodate between two to three hydrogen molecules in close proximity to the MOF framework at or near saturation pressures. Further, the net attractive potential energy interactions are dominated by van der Waals interactions in the highly polar MOF - induction changes the structure of the sorbed hydrogen but not the MOF storage capacity. Thus, narrow channels, while providing reasonably promising isosteric heat values, are not the best choice of topology for gas sorption applications from both a molecular and gravimetric perspective.}, number={3}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Stern, Abraham C. and Belof, Jonathan L. and Eddaoudi, Mohamed and Space, Brian}, year={2012}, month={Jan}, pages={034705} }
 @article{belof_cioce_xu_zhang_space_woodcock_2011, title={Characterization of Tunable Radical Metal–Carbenes: Key Intermediates in Catalytic Cyclopropanation}, volume={30}, ISSN={0276-7333 1520-6041}, url={http://dx.doi.org/10.1021/om2001348}, DOI={10.1021/om2001348}, abstractNote={A new class of radical metal-carbene complex has been characterized as having Fischer-like orbital interactions and adjacent π acceptor stabilization. Density Functional Theory (DFT) along with Natural Bond Orbital (NBO) analysis and Charge Decomposition Analysis (CDA) has given insight into the electronics of this catalytic intermediate in an open-shell cobalt-porphyrin, [Co(Por)], system. The complex has a single bond from the metal to the carbene and has radical character with localized spin density on the carbene carbon. In addition, the carbene carbon is found to be nucleophilic and "tunable" through the introduction of different α-carbon substituents. Finally, based on these findings, rational design strategies are proposed which should lead to the enhancement of catalytic activity.}, number={10}, journal={Organometallics}, publisher={American Chemical Society (ACS)}, author={Belof, Jonathan L. and Cioce, Christian R. and Xu, Xue and Zhang, X. Peter and Space, Brian and Woodcock, H. Lee}, year={2011}, month={May}, pages={2739–2746} }
 @article{chen_stern_space_johnson_2010, title={Atomic Charges Derived from Electrostatic Potentials for Molecular and Periodic Systems}, volume={114}, ISSN={1089-5639 1520-5215}, url={http://dx.doi.org/10.1021/jp103944q}, DOI={10.1021/jp103944q}, abstractNote={We present a method for fitting atomic charges to the electrostatic potential (ESP) of periodic and nonperiodic systems. This method is similar to the method of Campa et al. [ J. Chem. Theory Comput. 2009, 5, 2866]. We compare the Wolf and Ewald long-range electrostatic summation methods in calculating the ESP for periodic systems. We find that the Wolf summation is computationally more efficient than the Ewald summation by about a factor of 5 with comparable accuracy. Our analysis shows that the choice of grid mesh size influences the fitted atomic charges, especially for systems with buried (highly coordinated) atoms. We find that a maximum grid spacing of 0.2−0.3 A is required to obtain reliable atomic charges. The effect of the exclusion radius for point selection is assessed; we find that the common choice of using the van der Waals (vdW) radius as the exclusion radius for each atom may result in large deviations between the ESP generated from the ab initio calculations and that computed from the fitted charges, especially for points closest to the exclusion radii. We find that a larger value of exclusion radius than commonly used, 1.3 times the vdW radius, provides more reliable results. We find that a penalty function approach for fitting charges for buried atoms, with the target charge taken from Bader charge analysis, gives physically reasonable results.}, number={37}, journal={The Journal of Physical Chemistry A}, publisher={American Chemical Society (ACS)}, author={Chen, De-Li and Stern, Abraham C. and Space, Brian and Johnson, J. Karl}, year={2010}, month={Sep}, pages={10225–10233} }
 @article{hilker_fields_stern_space_zhang_harmon_2010, title={Dielectric analysis of poly(methyl methacrylate) zinc(II) mono-pinacolborane diphenylporphyrin composites}, volume={51}, ISSN={0032-3861}, url={http://dx.doi.org/10.1016/j.polymer.2010.08.049}, DOI={10.1016/j.polymer.2010.08.049}, abstractNote={Poly(methyl methacrylate) (PMMA) composites were made from a polar metalloporphyrin [5-(4′,4′,5′,5′-tetramethyl[1′,3′,2′]dioxaborolan-2′-yl)-10,20-diphenylporphyrinato]zinc(II) (Zn(II)Bpin-DPP) in select weight % (wt%). Differential Scanning Calorimetry (DSC) showed that porphyrin acted as an antiplasticizer raising the glass transition (Tg) from 105 °C to 123 °C. Dielectric Analysis (DEA) was performed in the frequency range of 0.3 Hz to 100 kHz between −150 and 270 °C. Permittivity (ɛ′), loss factor (ɛ″) and dielectric response of beta (β), alpha beta (αβ), and conductivity relaxations were studied. Previous DEA data was limited to 190 °C. This study brings analysis to 270 °C which is start point for the first part of PMMA degradation. Thus forwarding DEA can be used to evaluate PMMA degradation. The electric modulus formalism is used to reveal the β and conductivity relaxations. The apparent activation energies (Ea) for the molecular relaxations are presented. AC (σAC) and DC (σDC) conductivity are also evaluated.}, number={21}, journal={Polymer}, publisher={Elsevier BV}, author={Hilker, Brent and Fields, Kimberly B. and Stern, Abraham and Space, Brian and Zhang, X. Peter and Harmon, Julie P.}, year={2010}, month={Oct}, pages={4790–4805} }
 @article{mcintyre_lowe_belof_ivkovic_shafer_space_merkler_2010, title={Evidence for Substrate Preorganization in the Peptidylglycine α-Amidating Monooxygenase Reaction Describing the Contribution of Ground State Structure to Hydrogen Tunneling}, volume={132}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja1019194}, DOI={10.1021/ja1019194}, abstractNote={Peptidylglycine α-amidating monooxygenase (PAM) is a bifunctional enzyme which catalyzes the post-translational modification of inactive C-terminal glycine-extended peptide precursors to the corresponding bioactive α-amidated peptide hormone. This conversion involves two sequential reactions both of which are catalyzed by the separate catalytic domains of PAM. The first step, the copper-, ascorbate-, and O(2)-dependent stereospecific hydroxylation at the α-carbon of the C-terminal glycine, is catalyzed by peptidylglycine α-hydroxylating monooxygenase (PHM). The second step, the zinc-dependent dealkylation of the carbinolamide intermediate, is catalyzed by peptidylglycine amidoglycolate lyase. Quantum mechanical tunneling dominates PHM-dependent C(α)-H bond activation. This study probes the substrate structure dependence of this chemistry using a set of N-acylglycine substrates of varying hydrophobicity. Primary deuterium kinetic isotope effects (KIEs), molecular mechanical docking, alchemical free energy perturbation, and equilibrium molecular dynamics were used to study the role played by ground-state substrate structure on PHM catalysis. Our data show that all Ν-acylglycines bind sequentially to PHM in an equilibrium-ordered fashion. The primary deuterium KIE displays a linear decrease with respect to acyl chain length for straight-chain N-acylglycine substrates. Docking orientation of these substrates displayed increased dissociation energy proportional to hydrophobic pocket interaction. The decrease in KIE with hydrophobicity was attributed to a preorganization event which decreased reorganization energy by decreasing the conformational sampling associated with ground state substrate binding. This is the first example of preorganization in the family of noncoupled copper monooxygenases.}, number={46}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={McIntyre, Neil R. and Lowe, Edward W., Jr. and Belof, Jonathan L. and Ivkovic, Milena and Shafer, Jacob and Space, Brian and Merkler, David J.}, year={2010}, month={Nov}, pages={16393–16402} }
 @article{belof_stern_space_2009, title={A Predictive Model of Hydrogen Sorption for Metal−Organic Materials}, volume={113}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp901988e}, DOI={10.1021/jp901988e}, abstractNote={Newly developed hydrogen and MOM (Metal−Organic Materials) potential energy functions for molecular simulation are presented. They are designed to be highly transferable while still describing sorbate−MOM interactions with predictive accuracy. Specifically, they are shown to quantitatively describe hydrogen sorption, including isosteric heats, in MOF-5 over the broad temperature and pressure ranges that have been examined experimentally. The approach that is adopted is general and demonstrates that highly accurate and predictive models of molecular interaction with MOMs are quite feasible. Molecular interactions giving rise to the isosteric heat have been characterized and validated against the experimentally relevant data. Finally, inspection of the isothermal compressibility of hydrogen in MOF-5 reveals that under saturating high-pressure conditions (even at temperatures well above the neat boiling point) the state of hydrogen is characteristic of a liquid, i.e., with a compressibility similar to that o...}, number={21}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Belof, Jonathan L. and Stern, Abraham C. and Space, Brian}, year={2009}, month={May}, pages={9316–9320} }
 @article{belof_stern_space_2008, title={An Accurate and Transferable Intermolecular Diatomic Hydrogen Potential for Condensed Phase Simulation}, volume={4}, ISSN={1549-9618 1549-9626}, url={http://dx.doi.org/10.1021/ct800155q}, DOI={10.1021/ct800155q}, abstractNote={An anisotropic many-body H2 potential energy function has been developed for use in heterogeneous systems. The intermolecular potential has been derived from first principles and expressed in a form that is readily transferred to exogenous systems, e.g. in modeling H2 sorption in solid-state materials. Explicit many-body polarization effects, known to be important in simulating hydrogen at high density, are incorporated. The analytic form of the potential energy function is suitable for methods of statistical physics, such as Monte Carlo or Molecular Dynamics simulation. The model has been validated on dense supercritical hydrogen and demonstrated to reproduce the experimental data with high accuracy.}, number={8}, journal={Journal of Chemical Theory and Computation}, publisher={American Chemical Society (ACS)}, author={Belof, Jonathan L. and Stern, Abraham C. and Space, Brian}, year={2008}, month={Jul}, pages={1332–1337} }
 @article{space_2008, title={Making a life in the physical sciences}, volume={29}, ISSN={0894-3796}, url={http://dx.doi.org/10.1002/job.534}, DOI={10.1002/job.534}, abstractNote={As a practicing physical chemist, I argue that the challenges faced by the physical sciences have more parallels with organization science than it might first appear. While the physical sciences do represent a strong paradigm endeavor, many of the same issues that were raised in the article “Making a life in the field of organizational science” arise in physical sciences. An essential difference between the physical sciences and organization science is the essentially capital intensive nature of our research. Ironically, the constant pursuit of the requisite research dollars leads to substantial similarity between the fields. The state of academic physical sciences is analyzed in this context informed by the current state of research funding in the United States. Copyright © 2008 John Wiley & Sons, Ltd.}, number={6}, journal={Journal of Organizational Behavior}, publisher={Wiley}, author={Space, Brian}, year={2008}, month={May}, pages={755–759} }
 @article{mokdad_belof_yi_shuler_mclaughlin_space_larsen_2008, title={Photophysical Studies of the Trans to Cis Isomerization of the Push−Pull Molecule: 1-(Pyridin-4-yl)-2-(N-methylpyrrol-2-yl)ethene (mepepy)}, volume={112}, ISSN={1089-5639 1520-5215}, url={http://dx.doi.org/10.1021/jp803268r}, DOI={10.1021/jp803268r}, abstractNote={Organic molecules possessing intramolecular charge-transfer properties (D-pi-A type molecules) are of key interest particularly in the development of new optoelectronic materials as well as photoinduced magnetism. One such class of D-pi-A molecules that is of particular interest contains photoswitchable intramolecular charge-transfer states via a photoisomerizable pi-system linking the donor and acceptor groups. Here we report the photophysical and electronic properties of the trans to cis isomerization of 1-(pyridin-4-yl)-2-(N-methylpyrrol-2-yl)ethene ligand (mepepy) in aqueous solution using photoacoustic calorimetry (PAC) and theoretical methods. Density functional theory (DFT) calculations demonstrate a global energy difference between cis and trans isomers of mepepy to be 8 kcal mol(-1), while a slightly lower energy is observed between the local minima for the trans and cis isomers (7 kcal mol(-1)). Interestingly, the trans isomer appears to exhibit two ground-state minima separated by an energy barrier of approximately 9 kcal mol(-1). Results from the PAC studies indicate that the trans to cis isomerization results in a negligible volume change (0.9 +/- 0.4 mL mol(-1)) and an enthalpy change of 18 +/- 3 kcal mol(-1). The fact that the acoustic waves associated with the trans to cis transition of mepepy overlap in frequency with those of a calorimetric reference implies that the conformational transition occurs faster than the approximately 50 ns response time of the acoustic detector. Comparison of the experimental results with theoretical studies provide evidence for a mechanism in which the trans to cis isomerization of mepepy results in the loss of a hydrogen bond between a water molecule and the pyridine ring of mepepy.}, number={36}, journal={The Journal of Physical Chemistry A}, publisher={American Chemical Society (ACS)}, author={Mokdad, Audrey and Belof, Jonathan L. and Yi, Sung Wook and Shuler, Stephen E. and McLaughlin, Mark L. and Space, Brian and Larsen, Randy W.}, year={2008}, month={Sep}, pages={8310–8315} }
 @article{neipert_space_2007, title={A Distributed Hyperpolarizability Model for Liquid Water}, volume={3}, ISSN={1574-0404}, url={http://dx.doi.org/10.1163/157404007782913291}, DOI={10.1163/157404007782913291}, abstractNote={In a recent work a novel, molecular dynamics (MD) based, theory was presented that provides a direct means to calculate the third order contributions to sum frequency vibrational spectroscopy (SFVS) at charged interfaces.[1] This contribution is described by a time correlation function (TCF) of the system's total hyperpolarizability (β) and dipole. A system's hyperpolarizability[2, 3, 4, 5] is difficult to calculate on the fly – no appropriate non-electronic structure (ES) techniques exist. In this work, such a model is developed for liquid water based on a formalism proposed previously.[1] The model is parametrized from and tested against, ab initio ES calculations. It was found that it is possible to reproduce the hyperpolarizability tensor of a gas phase water molecule and a water dimer accurately. Also, most relevant components of the hyperpolarizability derivative tensor of both the water and water dimer were also accurately fit, however, some elements were not able to be simultaneously reproduced. The model was also tested to assess whether or not it could reproduce the three non-zero condensed phase water hyperpolarizability tensor components. It was found that the model could capture two of the three relevant components.}, number={2}, journal={Computing Letters}, publisher={Brill}, author={Neipert, C. and Space, B.}, year={2007}, month={Nov}, pages={431–440} }
 @article{neipert_space_roney_2007, title={Generalized Computational Time Correlation Function Approach:  Quantifying Quadrupole Contributions to Vibrationally Resonant Second-Order Interface-Specific Optical Spectroscopies†}, volume={111}, ISSN={1932-7447 1932-7455}, url={http://dx.doi.org/10.1021/jp066934c}, DOI={10.1021/jp066934c}, abstractNote={Second-order optical measurements are interface specific (vanishing in isotropic media) in the dipole approximation. Given this approximation, there has been debate, and it is of much interest, to determine the quantitative contribution of bulk media to the second-order optical spectra. Simple estimates and extant experiments have clearly demonstrated that quadrupole contributions can be on the order of dipole contributions for some liquids. However, no definitive set of criteria exists to determine when this will be the case. To this end, a computationally tractable time correlation function formalism is developed that goes beyond the dipole approximation, accounting for dipole, dipole−quadrupole, and pure quadrupole contributions. This theory generalizes an earlier description by both avoiding the rotating wave approximation and including higher order quadrupole contributions. It is, therefore, capable of also describing sum frequency vibrational spectroscopy (SFVS) spectra at low and intermediate frequ...}, number={25}, journal={The Journal of Physical Chemistry C}, publisher={American Chemical Society (ACS)}, author={Neipert, Christine and Space, Brian and Roney, Alfred B.}, year={2007}, month={Jun}, pages={8749–8756} }
 @article{belof_stern_eddaoudi_space_2007, title={On the Mechanism of Hydrogen Storage in a Metal−Organic Framework Material}, volume={129}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja0737164}, DOI={10.1021/ja0737164}, abstractNote={Monte Carlo simulations were performed modeling hydrogen sorption in a recently synthesized metal-organic framework material (MOF) that exhibits large molecular hydrogen uptake capacity. The MOF is remarkable because at 78 K and 1.0 atm it sorbs hydrogen at a density near that of liquid hydrogen (at 20 K and 1.0 atm) when considering H2 density in the pores. Unlike most other MOFs that have been investigated for hydrogen storage, it has a highly ionic framework and many relatively small channels. The simulations demonstrate that it is both of these physical characteristics that lead to relatively strong hydrogen interactions in the MOF and ultimately large hydrogen uptake. Microscopically, hydrogen interacts with the MOF via three principle attractive potential energy contributions: Van der Waals, charge-quadrupole, and induction. Previous simulations of hydrogen storage in MOFs and other materials have not focused on the role of polarization effects, but they are demonstrated here to be the dominant contribution to hydrogen physisorption. Indeed, polarization interactions in the MOF lead to two distinct populations of dipolar hydrogen that are identified from the simulations that should be experimentally discernible using, for example, Raman spectroscopy. Since polarization interactions are significantly enhanced by the presence of a charged framework with narrow pores, MOFs are excellent hydrogen storage candidates.}, number={49}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Belof, Jonathan L. and Stern, Abraham C. and Eddaoudi, Mohamed and Space, Brian}, year={2007}, month={Dec}, pages={15202–15210} }
 @article{ridley_stern_green_devane_space_miksosvska_larsen_2006, title={A combined photothermal and molecular dynamics method for determining molecular volume changes}, volume={418}, ISSN={0009-2614}, url={http://dx.doi.org/10.1016/j.cplett.2005.10.093}, DOI={10.1016/j.cplett.2005.10.093}, abstractNote={Here, we present synergistically combined experimental and theoretical approaches to describe the molecular volume change associated with the photoisomerization of aqueous trans-azobenzene to cis-azobenzene. Although the cis isomer is sterically larger a volume contraction (trans–cis) of 4 mL/mol is observed by photoacoustic calorimetry in aqueous solution. Theoretical methods predict the same volume contraction and have determined the origin to be due to electrostriction arising from the newly formed dipolar species.}, number={1-3}, journal={Chemical Physics Letters}, publisher={Elsevier BV}, author={Ridley, Christina and Stern, Abraham C. and Green, Tony and DeVane, Russell and Space, Brian and Miksosvska, Jaroslava and Larsen, Randy W.}, year={2006}, month={Jan}, pages={137–141} }
 @article{neipert_space_2006, title={A time correlation function theory describing static field enhanced third order optical effects at interfaces}, volume={125}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.2397687}, DOI={10.1063/1.2397687}, abstractNote={Sum vibrational frequency spectroscopy, a second order optical process, is interface specific in the dipole approximation. At charged interfaces, there exists a static field, and as a direct consequence, the experimentally detected signal is a combination of enhanced second and static field induced third order contributions. There is significant evidence in the literature of the importance/relative magnitude of this third order contribution, but no previous molecularly detailed approach existed to separately calculate the second and third order contributions. Thus, for the first time, a molecularly detailed time correlation function theory is derived here that allows for the second and third order contributions to sum frequency vibrational spectra to be individually determined. Further, a practical, molecular dynamics based, implementation procedure for the derived correlation functions that describe the third order phenomenon is also presented. This approach includes a novel generalization of point atomic polarizability models to calculate the hyperpolarizability of a molecular system. The full system hyperpolarizability appears in the time correlation functions responsible for third order contributions in the presence of a static field.}, number={22}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Neipert, Christine and Space, Brian}, year={2006}, month={Dec}, pages={224706} }
 @article{devane_kasprzyk_space_keyes_2006, title={Theoretical Investigation of the Temperature Dependence of the Fifth-Order Raman Response Function of Fluid and Liquid Xenon†}, volume={110}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/jp055275l}, DOI={10.1021/jp055275l}, abstractNote={The temperature dependence of the fifth-order Raman response function, R(5)(t1,t2), is calculated for fluid xenon by employing a recently developed time-correlation function (TCF) theory. The TCF theory expresses the two-dimensional (2D) Raman quantum response function in terms of a two-time, computationally tractable, classical TCF. The theory was shown to be in excellent agreement with existing exact classical MD calculations for liquid xenon as well as reproducing line shape characteristics predicted by earlier theoretical work. It is applied here to investigate the temperature dependence of the fifth-order Raman response function in fluid xenon. In general, the characteristic line shapes are preserved over the temperature range investigated (for the reduced temperature points T* = 0.5, 1.0, and 2.0); differences in the signal decay times and a large decline in intensity with decreasing temperature (and associated anharmonicity) are observed. In addition, there are some signature features that were not observed in earlier results for T* = 1. The most dramatic difference in line shape is observed for the polarization condition, xxzzxx, that shows a vibrational echo peak. In contrast, the fully polarized signal changes mainly in magnitude.}, number={8}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={DeVane, Russell and Kasprzyk, Christina and Space, Brian and Keyes, T.}, year={2006}, month={Mar}, pages={3773–3781} }
 @article{perry_neipert_space_moore_2006, title={Theoretical Modeling of Interface Specific Vibrational Spectroscopy:  Methods and Applications to Aqueous Interfaces}, volume={106}, ISSN={0009-2665 1520-6890}, url={http://dx.doi.org/10.1021/cr040379y}, DOI={10.1021/cr040379y}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheoretical Modeling of Interface Specific Vibrational Spectroscopy: Methods and Applications to Aqueous InterfacesAngela Perry, Christine Neipert, Brian Space, and Preston B. MooreView Author Information Department of Chemistry, University of South Florida, Tampa, Florida 33620-5250 Department of Chemistry and Biochemistry, University of the Sciences in Philadelphia, Philadelphia, Pennsylvania 19104 Cite this: Chem. Rev. 2006, 106, 4, 1234–1258Publication Date (Web):February 24, 2006Publication History Received17 June 2005Published online24 February 2006Published inissue 1 April 2006https://doi.org/10.1021/cr040379yCopyright © 2006 American Chemical SocietyRequest reuse permissionsArticle Views1483Altmetric-Citations150LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (875 KB) Get e-AlertscloseSUBJECTS:Interfaces,Molecular structure,Molecules,Nonlinear optics,Polarization Get e-Alerts}, number={4}, journal={Chemical Reviews}, publisher={American Chemical Society (ACS)}, author={Perry, Angela and Neipert, Christine and Space, Brian and Moore, Preston B.}, year={2006}, month={Apr}, pages={1234–1258} }
 @article{devane_space_jansen_keyes_2006, title={Time correlation function and finite field approaches to the calculation of the fifth order Raman response in liquid xenon}, volume={125}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.2403129}, DOI={10.1063/1.2403129}, abstractNote={The fifth order, two-dimensional Raman response in liquid xenon is calculated via a time correlation function (TCF) theory and the numerically exact finite field method. Both employ classical molecular dynamics simulations. The results are shown to be in excellent agreement, suggesting the efficacy of the TCF approach, in which the response function is written approximately in terms of a single classical multitime TCF.}, number={23}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={DeVane, Russell and Space, Brian and Jansen, Thomas l. C. and Keyes, T.}, year={2006}, month={Dec}, pages={234501} }
 @article{perry_neipert_kasprzyk_green_space_moore_2005, title={A theoretical description of the polarization dependence of the sum frequency generation spectroscopy of the water/vapor interface}, volume={123}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.2046630}, DOI={10.1063/1.2046630}, abstractNote={An improved time correlation function (TCF) description of sum frequency generation (SFG) spectroscopy was developed and applied to theoretically describing the spectroscopy of the ambient water/vapor interface. A more general TCF expression than was published previously is presented-it is valid over the entire vibrational spectrum for both the real and imaginary parts of the signal. Computationally, earlier time correlation function approaches were limited to short correlation times that made signal processing challenging. Here, this limitation is overcome, and well-averaged spectra are presented for the three independent polarization conditions that are possible for electronically nonresonant SFG. The theoretical spectra compare quite favorably in shape and relative magnitude to extant experimental results in the O-H stretching region of water for all polarization geometries. The methodological improvements also allow the calculation of intermolecular SFG spectra. While the intermolecular spectrum of bulk water shows relatively little structure, the interfacial spectra (for polarizations that are sensitive to dipole derivatives normal to the interface--SSP and PPP) show a well-defined intermolecular mode at 875 cm(-1) that is comparable in intensity to the rest of the intermolecular structure, and has an intensity that is approximately one-sixth of the magnitude of the intense free O-H stretching peak. Using instantaneous normal mode methods, the resonance is shown to be due to a wagging mode localized on a single water molecule, almost parallel to the interface, with two hydrogens displaced normal to the interface, and the oxygen anchored in the interface. We have also uncovered the origin of another intermolecular mode at 95 cm(-1) for the SSP and PPP spectra, and at 220 cm(-1) for the SPS spectra. These resonances are due to hindered translations perpendicular to the interface for the SSP and PPP spectra, and translations parallel to the interface for the SPS spectra. Further, by examining the real and imaginary parts of the SFG signal, several resonances are shown to be due to a single spectroscopic species while the "donor" O-H region is shown to consist of three distinct species-consistent with an earlier experimental analysis.}, number={14}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Perry, Angela and Neipert, Christine and Kasprzyk, Christina Ridley and Green, Tony and Space, Brian and Moore, Preston B.}, year={2005}, month={Oct}, pages={144705} }
 @article{devane_ridley_space_keyes_2005, title={Applications of a time correlation function theory for the fifth-order Raman response function I: Atomic liquids}, volume={123}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.2038768}, DOI={10.1063/1.2038768}, abstractNote={Multidimensional spectroscopy has the ability to provide great insight into the complex dynamics and time-resolved structure of liquids. Theoretically describing these experiments requires calculating the nonlinear-response function, which is a combination of quantum-mechanical time correlation functions R5(t1,t2) was expressed with a two-time, computationally tractable, classical TCF. Writing the response function in terms of classical TCFs brings the full power of atomistically detailed molecular dynamics to the problem. In this paper, the new TCF theory is employed to calculate the fifth-order Raman response function for liquid xenon and investigate several of the polarization conditions for which experiments can be performed on an isotropic system. The theory is shown to reproduce line-shape characteristics predicted by earlier theoretical work.}, number={19}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={DeVane, Russell and Ridley, Christina and Space, Brian and Keyes, T.}, year={2005}, month={Nov}, pages={194507} }
 @article{perry_neipert_ridley_space_moore_2005, title={Identification of a wagging vibrational mode of water molecules at the water/vapor interface}, volume={71}, ISSN={1539-3755 1550-2376}, url={http://dx.doi.org/10.1103/physreve.71.050601}, DOI={10.1103/physreve.71.050601}, abstractNote={An improved time correlation function description of sum frequency generation (SFG) spectroscopy was applied to theoretically describe the water/vapor interface. The resulting spectra compare favorably in shape and relative magnitude to extant experimental results in the O-H stretching region of water. Further, the SFG spectra show a well-defined intermolecular mode at 875 cm(-1) that has significant intensity. The resonance is due to a wagging mode localized on a single water molecule. It represents a well-defined population of water molecules at the interface that, along with the free O-H modes, represent the dominant interfacial species.}, number={5}, journal={Physical Review E}, publisher={American Physical Society (APS)}, author={Perry, Angela and Neipert, Christine and Ridley, Christina and Space, Brian and Moore, Preston B.}, year={2005}, month={May} }
 @article{roney_space_castner_napoleon_moore_2004, title={A Molecular Dynamics Study of Aggregation Phenomena in Aqueousn-Propanol}, volume={108}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/jp037922j}, DOI={10.1021/jp037922j}, abstractNote={Low-frequency Raman studies of various concentrations of aqueous n-propanol at room temperature indicate that both water and n-propanol form single-component aggregates in solution. Small-angle X-r...}, number={22}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Roney, Alfred B. and Space, Brian and Castner, Edward W. and Napoleon, Raeanne L. and Moore, Preston B.}, year={2004}, month={Jun}, pages={7389–7401} }
 @article{devane_space_perry_neipert_ridley_keyes_2004, title={A time correlation function theory of two-dimensional infrared spectroscopy with applications to liquid water}, volume={121}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.1776119}, DOI={10.1063/1.1776119}, abstractNote={A theory describing the third-order response function R((3))(t(1),t(2),t(3)), which is associated with two-dimensional infrared (2DIR) spectroscopy, has been developed. R((3)) can be written as sums and differences of four distinct quantum mechanical dipole (multi)time correlation functions (TCF's), each with the same classical limit; the combination of TCF's has a leading contribution of order variant Planck's over 2pi (3) and thus there is no obvious classical limit that can be written in terms of a TCF. In order to calculate the response function in a form amenable to classical mechanical simulation techniques, it is rewritten approximately in terms of a single classical TCF, B(R)(t(1),t(2),t(3))=micro(j)(t(2)+t(1))micro(i)(t(3)+t(2)+t(1))micro(k)(t(1))micro(l)(0), where the subscripts denote the Cartesian dipole directions. The response function is then given, in the frequency domain, as the Fourier transform of a classical TCF multiplied by frequency factors. This classical expression can then further be quantum corrected to approximate the true response function, although for low frequency spectroscopy no correction is needed. In the classical limit, R((3)) becomes the sum of multidimensional time derivatives of B(R)(t(1),t(2),t(3)). To construct the theory, the response function's four TCF's are rewritten in terms of a single TCF: first, two TCF's are eliminated from R((3)) using frequency domain detailed balance relationships, and next, two more are removed by relating the remaining TCF's to each other within a harmonic oscillator approximation; the theory invokes a harmonic approximation only in relating the TCF's and applications of theory involve fully anharmonic, atomistically detailed molecular dynamics (MD). Writing the response function as a single TCF thus yields a form amenable to calculation using classical MD methods along with a suitable spectroscopic model. To demonstrate the theory, the response function is obtained for liquid water with emphasis on the OH stretching portion of the spectrum. This approach to evaluating R((3)) can easily be applied to chemically interesting systems currently being explored experimentally by 2DIR and to help understand the information content of the emerging multidimensional spectroscopy.}, number={8}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={DeVane, Russell and Space, Brian and Perry, Angela and Neipert, Christine and Ridley, Christina and Keyes, T.}, year={2004}, month={Aug}, pages={3688–3701} }
 @article{devane_ridley_space_keyes_2004, title={Tractable theory of nonlinear response and multidimensional nonlinear spectroscopy}, volume={70}, ISSN={1539-3755 1550-2376}, url={http://dx.doi.org/10.1103/physreve.70.050101}, DOI={10.1103/physreve.70.050101}, abstractNote={Nonlinear spectroscopy provides insights into dynamics, but the response functions required for its interpretation pose a challenge to theorists. We proposed an approach in which the fifth-order response function [R5( t1, t2)] was expressed as a two-time classical time correlation function (TCF). Here, we present TCF theory results for R5( t1, t2) in liquid xenon. Using a first-order dipole-induced dipole polarizability model, the result is compared to an exact numerical calculation showing remarkable agreement. In addition, R5( t1, t2) is calculated using the exactly solved polarizability model, yielding different results and predicting an echo signal.}, number={5}, journal={Physical Review E}, publisher={American Physical Society (APS)}, author={DeVane, Russell and Ridley, Christina and Space, Brian and Keyes, T.}, year={2004}, month={Nov} }
 @article{devane_ridley_larsen_space_moore_chan_2003, title={A Molecular Dynamics Method for Calculating Molecular Volume Changes Appropriate for Biomolecular Simulation}, volume={85}, ISSN={0006-3495}, url={http://dx.doi.org/10.1016/s0006-3495(03)74703-1}, DOI={10.1016/s0006-3495(03)74703-1}, abstractNote={Photothermal methods permit measurement of molecular volume changes of solvated molecules over nanosecond timescales. Such experiments are an important tool in investigating complex biophysical phenomena including identifying transient species in solution. Developing a microscopic understanding of the origin of volume changes in the condensed phase is needed to complement the experimental measurements. A molecular dynamics (MD) method exploiting available simulation methodology is demonstrated here that both mimics experimental measurements and provides microscopic resolution to the thermodynamic measurements. To calculate thermodynamic volume changes over time, isothermal-isobaric (NPT) MD is performed on a solution for a chosen length of time and the volume of the system is thus established. A further simulation is then performed by "plucking" out a solute molecule of interest to determine the volume of the system in its absence. The difference between these volumes is the thermodynamic volume of the solute molecule. NPT MD allows the volume of the system to fluctuate over time and this results in a statistical uncertainty in volumes that are calculated. It is found in the systems investigated here that simulations lasting a few nanoseconds can discern volume changes of approximately 1.0 ml/mole. This precision is comparable to that achieved empirically, making the experimental and theoretical techniques synergistic. The technique is demonstrated here on model systems including neat water, both charged and neutral aqueous methane, and an aqueous beta-sheet peptide.}, number={5}, journal={Biophysical Journal}, publisher={Elsevier BV}, author={DeVane, Russell and Ridley, Christina and Larsen, Randy W. and Space, Brian and Moore, Preston B. and Chan, Sunney I.}, year={2003}, month={Nov}, pages={2801–2807} }
 @article{perry_ahlborn_space_moore_2003, title={A combined time correlation function and instantaneous normal mode study of the sum frequency generation spectroscopy of the water/vapor interface}, volume={118}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.1565994}, DOI={10.1063/1.1565994}, abstractNote={Theoretical approximations to the interface specific sum frequency generation (SFG) spectrum of O–H stretching at the water/vapor interface are constructed using time correlation function (TCF) and instantaneous normal mode (INM) methods. Both approaches lead to a (SSP polarization geometry) signal in excellent agreement with experimental measurements; the SFG spectrum of the entire water spectrum, both intermolecular and intramolecular, is reported. The observation that the INM spectrum is in agreement with the TCF result implies that motional narrowing effects play no role in the interfacial line shapes, in contrast to the O–H stretching dynamics in the bulk that leads to a narrowed line shape. This implies that (SSP) SFG spectroscopy is a probe of structure with dynamics not represented in the signal. The INM approach permits the elucidation of the molecular basis for the observed signal, and the motions responsible for the SFG line shape are well approximated as local O–H stretching modes. The complex...}, number={18}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Perry, Angela and Ahlborn, Heather and Space, Brian and Moore, Preston B.}, year={2003}, month={May}, pages={8411–8419} }
 @article{devane_ridley_space_keyes_2003, title={A time correlation function theory for the fifth order Raman response function with applications to liquid CS2}, volume={119}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.1601607}, DOI={10.1063/1.1601607}, abstractNote={A new theory for the fifth order Raman response function, R(5)(t1,t2), is presented. Using this result, R(5)(t1,t2) is shown to have a classical limit given by a combination of time derivatives of the real and imaginary parts of a two time correlation function (TCF) of the polarizability. In contrast with one time correlation functions, no exact analytic relationship exists between the real and imaginary parts of the quantum mechanical TCF that would allow the classical limit to be written in terms of classical TCF’s. Writing the nonlinear response function in terms of classical TCF’s would allow R(5)(t1,t2) to be calculated with minimal computational effort, in contrast to existing (exact) classical formulations. However, a simple approximate relationship is shown to exist between the real and imaginary parts of the two time TCF for a harmonic system with nonlinear polarizability. In the spirit of quantum correction, this relationship is used to write the exact classical response function in terms of cla...}, number={12}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={DeVane, Russell and Ridley, Christina and Space, Brian and Keyes, T.}, year={2003}, month={Sep}, pages={6073–6082} }
 @inbook{moore_ahlborn_space_2002, title={A Combined Time Correlation Function and Instantaneous Normal Mode Investigation of Liquid-State Vibrational Spectroscopy}, ISBN={084123762X 0841219206}, ISSN={1947-5918}, url={http://dx.doi.org/10.1021/bk-2002-0820.ch003}, DOI={10.1021/bk-2002-0820.ch003}, abstractNote={Our work investigates the instantaneous normal mode (INM) and time correlation function (TCF) of several different liquids and compares the results with the experimental infrared (IR) and Raman spectra. Our work demonstrates that INM and TCF methods can be used in a complementary fashion in describing liquid state vibrational spectroscopy. INM derived spectra often lead to inter-molecular spectra that are in agreement with corresponding TCF results, suggesting that the inter-molecular dynamics can be interpreted as oscillations. TCF derived spectra, while formally exact in the low frequency regime (hw ≪ kT), suffer severely from the need for quantum (detailed balance) correction at higher frequencies. Our approach is to compare TCF spectra with experiment to establish that our MD methods can reliably describe the system of interest, and to employ INM methods to analyze the molecular and dynamical basis for the observed spectroscopy. We have been able to}, booktitle={ACS Symposium Series}, publisher={American Chemical Society}, author={Moore, Preston B. and Ahlborn, Heather and Space, Brian}, year={2002}, month={Jun}, pages={30–43} }
 @article{constantine_gardecki_zhou_ziegler_ji_space_2001, title={A Novel Technique for the Measurement of Polarization-Specific Ultrafast Raman Responses}, volume={105}, ISSN={1089-5639 1520-5215}, url={http://dx.doi.org/10.1021/jp004277x}, DOI={10.1021/jp004277x}, abstractNote={A simple time domain method for the observation of polarization-specific Raman responses in electronically nonresonant materials is demonstrated. When a cutoff filter is placed in the probe beam path before the detector in the conventional pump−probe configuration, the in-phase dichroic optical heterodyne-detected (OHD) response is enhanced as compared to the usual putative corresponding dichroic response observed when the probe is not dispersed. The ultrafast excited OHD responses of CS2 obtained by this method are reported for parallel, perpendicular, and magic angle relative orientations of pump and probe pulse polarizations. The observed dispersed dichroic signal can be derived from the real part alone of the third-order nuclear response function. The decay of the CS2 isotropic response is found to be dominated by a ∼500 fs decay process for times longer than ∼0.7 ps. This relaxation time scale matches the nondiffusive exponential decay seen in the birefringent and dichroic anisotropic responses of CS2. Calculated instantaneous normal mode (INM) isotropic and anisotropic nuclear response functions are found to exhibit exponential decays in this same 500−600 fs time scale, suggesting that this decay component may be predominantly determined by the distribution of Raman-weighted density of states.}, number={43}, journal={The Journal of Physical Chemistry A}, publisher={American Chemical Society (ACS)}, author={Constantine, S. and Gardecki, J. A. and Zhou, Y. and Ziegler, L. D. and Ji, Xingdong and Space, Brian}, year={2001}, month={Nov}, pages={9851–9858} }
 @article{ji_ahlborn_space_moore_zhou_constantine_ziegler_2000, title={A combined instantaneous normal mode and time correlation function description of the optical Kerr effect and Raman spectroscopy of liquid CS2}, volume={112}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.481539}, DOI={10.1063/1.481539}, abstractNote={The depolarized reduced Raman and corresponding optical Kerr effect (OKE) spectral density of ambient CS2 have been calculated by way of time correlation function (TCF) and instantaneous normal mode (INM) methods and compared with experimental OKE data. When compared in the reduced Raman spectrum form, where the INM spectrum is proportional to the squared polarizability derivative weighted density of states (DOS), the INM results agree nearly quantitatively (at all but the lowest frequencies) with the TCF results. Both are in excellent agreement with experimental measurements. The INM signal has a significant contribution from the imaginary INMs. Within our INM theory of spectroscopy the imaginary INMs contribute like the real modes, at the magnitude of their imaginary frequency. When only the real modes are allowed to contribute, and the spectrum is rescaled to account for the missing degrees of freedom, the results are much poorer, as has been observed previously. When the spectra are compared in their ...}, number={9}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Ji, Xingdong and Ahlborn, Heather and Space, Brian and Moore, Preston B. and Zhou, Y. and Constantine, S. and Ziegler, L. D.}, year={2000}, month={Mar}, pages={4186–4192} }
 @article{ji_ahlborn_space_moore_2000, title={A theoretical investigation of the temperature dependence of the optical Kerr effect and Raman spectroscopy of liquid CS2}, volume={113}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.1318772}, DOI={10.1063/1.1318772}, abstractNote={The ambient pressure, temperature dependent optical Kerr effect (OKE) spectral density of CS2 has been calculated by way of time correlation function (TCF) and instantaneous normal mode (INM) methods and compared with corresponding experimental OKE data [R. A. Farrer, B. J. Loughnane, L. A. Deschenes, and J. T. Fourkas, J. Chem. Phys. 106, 6901 (1997)]. Over this temperature range the viscosity of CS2 varies by more than a factor of 5, and the molecular dynamics (MD) spectroscopic methods employed do an excellent job in capturing the associated changes in molecular motions that lead to the observed spectroscopy. The resulting TCF spectra are also in very good agreement with experimental measurements at all temperatures, and this is remarkable considering the range of conditions considered. When compared in the reduced Raman spectrum form, where the INM spectral density is proportional to the squared polarizability derivative weighted density of states (DOS), the INM results agree very well with the TCF re...}, number={19}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Ji, Xingdong and Ahlborn, Heather and Space, Brian and Moore, Preston B.}, year={2000}, month={Nov}, pages={8693–8699} }
 @article{shah_bowen_space_2000, title={An atomically detailed description of metal–dielectric interfaces: The crossover from surface to bulk conducting properties of Ag–Xe}, volume={112}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.481739}, DOI={10.1063/1.481739}, abstractNote={An atomically detailed simulation method designed to be efficacious for modeling conduction properties of closed shell atoms or molecules resident at interfaces that was developed earlier is applied to a metal–dielectric interface of Ag–Xe. The effective mass of conduction electrons resident at Ag–Xe interfaces as a function of the number of layers of xenon present has been measured experimentally by the Harris group [J. D. McNeill, R. L. Lingle, Jr., R. E. Jordan, D. F. Padowitz, and C. B. Harris, J. Chem. Phys. 105, 3883 (1996)]. Here a simple yet effective theoretical model of the interface is developed and the effective mass that results is in quantitative agreement with the empirical measurements. The effective mass of a conduction electron is calculated by solving the Schrodinger–Bloch equation using Lanczos grid methods to obtain the Bloch wave vector (k) dependent energies. The metal is treated as a continuum within the effective mass approximation for the purpose of calculating the eigenenergies....}, number={24}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Shah, Vaishali and Bowen, H. F. and Space, Brian}, year={2000}, month={Jun}, pages={10998–11004} }
 @article{ahlborn_space_moore_2000, title={The effect of isotopic substitution and detailed balance on the infrared spectroscopy of water: A combined time correlation function and instantaneous normal mode analysis}, volume={112}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.481408}, DOI={10.1063/1.481408}, abstractNote={We have recently demonstrated that simple classical molecular dynamics methods are capable of nearly quantitatively reproducing most of the intermolecular and intramolecular infrared (IR) spectroscopy of water [H. Ahlborn, X. Ji, B. Space, and P. B. Moore, J. Chem. Phys. 111, 10622 (1999)]. Here it is demonstrated that the result is robust by quantitatively reproducing experimentally measured D2O IR spectroscopy utilizing the same models. This suggests that the quantum effects associated with light atom motion are relatively unimportant. Instantaneous normal mode (INM) theory and the time correlation function (TCF) methodology are used in a complimentary fashion to analyze the molecular origin of the IR spectroscopy of deuterated water (D2O). The TCF methods demonstrate that our models of the dynamics and the system dipole are reasonable by successful quantitative comparison of the theoretical spectrum with experimental results. INM methodology is then employed to analyze what condensed phase motions are ...}, number={18}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Ahlborn, Heather and Space, Brian and Moore, Preston B.}, year={2000}, month={May}, pages={8083–8088} }
 @article{ahlborn_ji_space_moore_1999, title={A combined instantaneous normal mode and time correlation function description of the infrared vibrational spectrum of ambient water}, volume={111}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.480415}, DOI={10.1063/1.480415}, abstractNote={A formal connection is made between the vibrational density of states (DOS) of a liquid and its approximation by way of instantaneous normal modes (INMs). This analysis leads to a quantum generalization of the INM method (QINM), and to the possibility of evaluating the classical DOS exactly. Further, INM approximations to spectroscopic quantities (e.g., infrared absorption and Raman scattering) follow in a consistent manner by evaluating the appropriate golden rule expressions for harmonic oscillators, using the INM or QINM DOS in place of the true DOS. INM and QINM methods are then applied along with traditional time correlation function (TCF) methods to analyze the entire infrared (IR) spectrum of ambient water. The INM and TCF approaches are found to offer complimentary information. TCF methods are shown to offer an unexpectedly accurate description of the O–H stretching line shape. Further, the 19-fold enhancement in liquid phase absorption compared to the gas phase is also reproduced. INM and QINM methods are used to analyze the molecular origin of the water spectrum, and prove especially effective in analyzing the broad O–H stretching absorption. Further, it is argued that a motional narrowing picture is qualitatively useful in analyzing INM approximations to spectroscopy.}, number={23}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Ahlborn, Heather and Ji, Xingdong and Space, Brian and Moore, Preston B.}, year={1999}, month={Dec}, pages={10622–10632} }
 @article{esposito_juliani_space_1998, title={Electrostatic potential surfaces and geometries of novel N-acylglycine substrates for peptididylglycine A-amidating enzyme via electronic structure calculations and comparison with crystal structures}, volume={216}, journal={Abstracts of Papers of the American Chemical Society}, author={Esposito, E.X. and Juliani, J. and Space, B.}, year={1998}, pages={711–711} }
 @article{ahlborn_space_ji_moore_1998, title={Instantaneous normal mode theory of condensed phase absorption}, volume={216}, journal={Abstracts of Papers of the American Chemical Society}, author={Ahlborn, H.L. and Space, B. and Ji, X.D. and Moore, P.B.}, year={1998}, pages={765–765} }
 @article{esposito_space_manner_1998, title={The Utilization of Electronics Structure Calculations and Crystal Structures for the Structural Comparison of Novel N-Acylglycine Substrates for Peptidylglycine -Amidating Enzyme}, volume={71}, journal={Pennsylvania Academy of Science Publications}, author={Esposito, E.X. and Space, B. and Manner, B.}, year={1998}, pages={170–170} }
 @article{ji_space_ahlborn_1998, title={The infrared spectra of water from quantum mechanical and classical instantaneous normal mode (INM) theories}, volume={216}, journal={Abstracts of Papers of the American Chemical Society}, author={Ji, X.D. and Space, B. and Ahlborn, H.}, year={1998}, pages={760–760} }
 @article{esposito_space_1998, title={The structural comparison of novel N-acylglycine substrates for peptidylglycine alpha-amidating enzyme through the utilization of electronic structure calculations and crystal structures}, volume={215}, journal={Abstracts of Papers of the American Chemical Society}, author={Esposito, E.X. and Space, B.}, year={1998}, pages={218–218} }
 @article{space_bowen_1997, title={The origin and molecularly detailed calculation of the effective mass of excess electrons in condensed xenon}, volume={214}, journal={Abstracts of Papers of the American Chemical Society}, publisher={Space}, author={Space, B. and Bowen, F.}, year={1997}, pages={66- PHYS} }
 @article{esposito_space_merkler_1997, title={The structural activity relationship of novel N-Acylglycine substrates for peptidylglycine alpha-amidating enzyme through the utilization of computational chemistry}, volume={214}, journal={Abstracts of Papers of the American Chemical Society}, author={Esposito, E.X. and Space, B. and Merkler, D.}, year={1997}, pages={133–CHED} }
 @article{space_coker_1992, title={Dynamics of trapping and localization of excess electrons in simple fluids}, volume={96}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.462449}, DOI={10.1063/1.462449}, abstractNote={We employ a surface hopping trajectory method to study the rapid nonadiabatic relaxation after an excess electron is injected in unperturbed fluid helium. Several distinctively different relaxation processes, characterized by their relative importance at different times during the relaxation to a localized equilibrium state are detailed. These processes include: Short time nonadiabatic leakage from cavity to cavity, exploring the fluctuating unperturbed solvent structure. This relaxation involves slow drifting of the occupied state through a continuum of levels. This is followed by rapid diabatic expansion of a particular solvent cavity once the electron–solvent forces begin to take effect on the solvent atoms in a particular region of the fluid. We also study the importance of nonadiabatic hang up trajectories in which the excess electron gets caught in the first excited state of a bistable well potential offered by a pair of closely coupled cavities in the solvent. We study the density dependence of the...}, number={1}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Space, B. and Coker, D. F.}, year={1992}, month={Jan}, pages={652–663} }
 @phdthesis{space_1992, place={Boston, MA}, title={Energetics and dynamics of excess electrons in simple fluids}, school={Boston University}, author={Space, B.}, year={1992} }
 @article{space_coker_1992, title={Nonadiabatic Dynamics of Excess Electrons in Molten-Salts}, volume={203}, journal={Abstracts of Papers of the American Chemical Society}, author={Space, B. and Coker, D. F.}, year={1992}, pages={271- PHYS} }
 @article{coker_space_1992, title={Nonadiabatic Trapping and Localization Mechanisms of Excess Electrons in Fluids}, volume={203}, journal={Abstracts of Papers of the American Chemical Society}, author={Coker, D. F. and Space, B.}, year={1992}, pages={273– PHYS} }
 @article{space_coker_1991, title={Nonadiabatic dynamics of excited excess electrons in simple fluids}, volume={94}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.459920}, DOI={10.1063/1.459920}, abstractNote={We present a surface hopping trajectory method for studying nonadiabatic excess electronic relaxation in condensed systems. This approach is used to explore the nonadiabatic relaxation after photoexciting an equilibrated excess electron in dense fluid helium. We survey the different types of nonadiabatic phenomena which are important in excess electronic relaxation. Very rapid diabatic processes are common when the nuclear dynamics provides only weak couplings between the adiabatic states. This is generally the case when the states are localized in different regions of space. We find that the nuclear dynamics provides a mechanism for strong coupling between s‐ and p‐like states localized in the same solvent cavity. These strong nonadiabatic interactions can persist over a wide range of nuclear configurations and for many hundreds of femtoseconds.We present a surface hopping trajectory method for studying nonadiabatic excess electronic relaxation in condensed systems. This approach is used to explore the nonadiabatic relaxation after photoexciting an equilibrated excess electron in dense fluid helium. We survey the different types of nonadiabatic phenomena which are important in excess electronic relaxation. Very rapid diabatic processes are common when the nuclear dynamics provides only weak couplings between the adiabatic states. This is generally the case when the states are localized in different regions of space. We find that the nuclear dynamics provides a mechanism for strong coupling between s‐ and p‐like states localized in the same solvent cavity. These strong nonadiabatic interactions can persist over a wide range of nuclear configurations and for many hundreds of femtoseconds.}, number={3}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Space, B. and Coker, D. F.}, year={1991}, month={Feb}, pages={1976–1984} }
 @article{poliakoff_kelly_duffy_space_roy_southworth_white_1989, title={Interchannel interactions following shape resonant excitation of core electrons}, volume={129}, ISSN={0301-0104}, url={http://dx.doi.org/10.1016/0301-0104(89)80019-9}, DOI={10.1016/0301-0104(89)80019-9}, abstractNote={Interchannel coupling of a core electron shape resonance with a valence-hole ionic continuum is studied with vibrational resolution. A core-hole shape resonance is created via N2 (1s→continuum e−) photoabsorption, and this complex decays to form the N2+ (B2Σu+) state via continuum interchannel coupling. The vibrational branching ratios for the N2+ (B2Σu+) state are then determined from N2+ (B2Σu+→2Σg+) fluorescence. The molecular motion provides excellent sensitivity to the resonant excitation, as underscored by two observations. First, the vibrational branching ratios for resonant and nonresonant excitation are qualitatively different. Secondly, the rotational motion of the ion is affected by the resonant excitation. These measurements demonstrate that continuum interchannel coupling can be probed precisely via dispersed fluorescence.}, number={1}, journal={Chemical Physics}, publisher={Elsevier BV}, author={Poliakoff, E.D. and Kelly, L.A. and Duffy, L.M. and Space, B. and Roy, P. and Southworth, S.H. and White, M.G.}, year={1989}, month={Jan}, pages={65–71} }
 @article{kelly_duffy_space_poliakoff_roy_southworth_white_1989, title={Vibrationally resolved shape resonant photoionization of N2O}, volume={90}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.456097}, DOI={10.1063/1.456097}, abstractNote={We report a vibrationally resolved dispersed fluorescence study of 7σ−1 shape resonant photoionization in N2O. Previous work indicates that there are two shape resonances in the εσ channel, and our results demonstrate that the lower energy shape resonance (hνexc≊20 eV) results in non-Franck–Condon vibrational branching ratios over a wide range. Moreover, the cross section curves for alternative vibrational modes behave differently, and we show that the symmetric stretch exerts a greater influence on resonance behavior than the asymmetric stretching vibration. Such comparisons of vibrationally resolved partial cross section curves provide qualitative insights into the shape resonant photoionization dynamics for polyatomic targets. The higher energy shape resonance is apparently masked by the presence of the dominant nonresonant επ channel. In addition to information on the photoionization dynamics, these results also provide spectroscopic data on the ionic potential surfaces. Specifically, we obtain ratios of Franck–Condon factors for N2O+ (A→X) transitions which are useful for testing calculated properties of the ion.}, number={3}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Kelly, L. A. and Duffy, L. M. and Space, B. and Poliakoff, E. D. and Roy, P. and Southworth, S. H. and White, M. G.}, year={1989}, month={Feb}, pages={1544–1550} }
 @article{poliakoff_kelly_duffy_space_roy_southworth_white_1988, title={Vibrationally resolved electronic autoionization of core–hole resonances}, volume={89}, ISSN={0021-9606 1089-7690}, url={http://dx.doi.org/10.1063/1.454838}, DOI={10.1063/1.454838}, abstractNote={We investigate the dynamics of molecular core–hole decay using dispersed fluorescence from an ionic valence–hole state in N2. A core–hole excited state is created via the N2(1s→1 π*g) transition, and this state electronically autoionizes to the N+2(B 2Σ+u) state. The vibrational branching ratios for the N+2(B 2Σ+u) state are then determined from N+2(B 2Σ+u→X 2Σ+g) fluorescence. Fundamental aspects of core–hole state decay emerge clearly from these measurements. In particular, interference effects due to lifetime broadening of vibrational levels of the core–hole state can be investigated quantitatively using this method. As a result, dispersed fluorescence detection serves as a powerful tool for investigating R‐dependent aspects of molecular core–hole resonances. The experimental results do not agree with predictions based on previous theoretical developments, and possible causes for the discrepancy are discussed.}, number={7}, journal={The Journal of Chemical Physics}, publisher={AIP Publishing}, author={Poliakoff, E. D. and Kelly, L. A. and Duffy, L. M. and Space, B. and Roy, P. and Southworth, S. H. and White, M. G.}, year={1988}, month={Oct}, pages={4048–4053} }