@article{miller_mengell_shultz_kirk_2024, title={Metal-Ligand Exchange Coupling Alters the Open-Shell Ligand Electronic Structure in a Bis(semiquinone) Complex}, volume={3}, ISSN={["1520-510X"]}, url={https://doi.org/10.1021/acs.inorgchem.4c00380}, DOI={10.1021/acs.inorgchem.4c00380}, abstractNote={The electronic structure of the bis(dioxolene) bridging ligand -SQ2Th2- is responsive to metal-ligand magnetic exchange coupling. Comparison of the crystal structure of (NiSQ)2Th2 to that of (ZnSQ)2Th2 indicates an open-shell biradical ground state for the dinuclear Ni(II) complex compared to the closed-shell quinoidal character found in the dinuclear Zn(II) complex. Consistent with a comparison of bond lengths obtained by X-ray diffraction, the analysis of the variable-temperature magnetic susceptibility data for crystalline (NiSQ)2Th2 yields reduced SQ-SQ radical-radical magnetic exchange coupling (JSQ-SQ = -203 cm-1) compared to that of (ZnSQ)2Th2 (JSQ-SQ = -321 cm-1). The reduced SQ-SQ exchange coupling in (NiSQ)2Th2 derives from an attenuation of the SQ spin densities, which in turn is derived from the Ni-SQ antiferromagnetic exchange interactions. This reduction in SQ--SQ exchange that we observe for (NiSQ)2Th2 correlates with an effective lengthening of the bridge unit by ∼2.1 Å relative to that of (ZnSQ)2Th2. This magnitude of the effective increase in the bridge distance is consistent with the (NiSQ)2Th2 JSQ-SQ value lying between those of (ZnSQ)2Th2 and (ZnSQ)2Th3. The ability to modulate spin populations on an organic radical via pairwise Ni-SQ magnetic exchange interactions is a general way to affect electronic coupling in the Th-Th bridge. Our results suggest that metal-radical exchange coupling represents a powerful mechanism for tuning organic molecular electronic structure, with important implications for molecular electronics and molecular electron transport.}, journal={INORGANIC CHEMISTRY}, author={Miller, Paul D. and Mengell, Joshua and Shultz, David A. and Kirk, Martin L.}, year={2024}, month={Mar} }
 @article{kirk_shultz_marri_est_2024, title={Photoinduced Magnetic Exchange-Jump Promotes Ground State Biradical Electron Spin Polarization}, volume={3}, ISSN={["1520-5126"]}, url={https://doi.org/10.1021/jacs.4c00930}, DOI={10.1021/jacs.4c00930}, abstractNote={Photoinduced electron spin polarization (ESP) is reported in the electronic ground states of three Pt(II) complexes comprised of two S = 1/2 nitronyl nitroxide (NN) radicals attached through different length para-phenylethynyl bridges to the 3,6 positions of a catecholate (CAT, donor) and 4,4'-di-tert-butyl-2,2'-bipyridine (bpy, acceptor). Complexes 1-3 have from 17 to 41 bonds separating NN radicals and display cw-EPR spectra consistent with |JNN-NN| ≫ |aN|, |JNN-NN| ≥ |aN|, and |JNN-NN| < |aN|, respectively, where JNN-NN is the magnetic exchange coupling between NN radicals in the electronic ground state, and aN is the isotropic 14N hyperfine coupling constant. Light-induced transient EPR spectra characterized as enhanced ground-state absorption were observed for all three complexes using 532 nm pulsed laser excitation into the ligand-to-ligand charge transfer (LL'CT) band of the (CAT)Pt(bpy) chromophore. The magnitude of the observed ESP increases in the order 1 < 2 < 3 and is inversely correlated with the magnitude of ground-state JNN-NN. In addition to the experimental observation of net absorptive polarization in 1-3, light excitation also produces multiplet polarization in 2. Since the weak dipolar coupling leads to a strong spectral overlap of the absorptive and emissive components, the multiplet polarization is not observed in 1 and 3 and is very weak in 2. The ability to spin-polarize multiple radical spins with a single photon is anticipated to advance new photoinduced multi qubit/qudit ESP protocols for quantum information science applications.}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Kirk, Martin L. and Shultz, David A. and Marri, Anil Reddy and Est, Art}, year={2024}, month={Mar} }
 @article{kirk_shultz_hewitt_marri_est_2023, title={Competitive reversed quartet mechanisms for photogenerated ground state electron spin polarization}, volume={14}, ISSN={["2041-6539"]}, url={https://doi.org/10.1039/D3SC03049K}, DOI={10.1039/D3SC03049K}, abstractNote={Different excited state equilibration pathways yield ground-state electron spin polarization of radical-elaborated platinum(ii) complexes. The equilibration pathways are controlled through designed molecular conformation.}, number={36}, journal={CHEMICAL SCIENCE}, author={Kirk, Martin L. and Shultz, David A. and Hewitt, Patrick and Marri, Anil Reddy and Est, Art}, year={2023}, month={Sep}, pages={9689–9695} }
 @article{kirk_shultz_hewitt_marri_est_2023, title={Competitive reversed quartet mechanisms for photogenerated ground state electron spin polarization}, volume={8}, ISSN={["2041-6539"]}, DOI={10.1039/d3sc03049}, journal={CHEMICAL SCIENCE}, author={Kirk, Martin L. and Shultz, David A. and Hewitt, Patrick and Marri, Anil Reddy and Est, Art}, year={2023}, month={Aug} }
 @article{shultz_stephenson_kirk_2023, title={Dinuclear ligand-to-ligand charge transfer complexes}, volume={1}, ISSN={["1477-9234"]}, url={https://doi.org/10.1039/D2DT03385B}, DOI={10.1039/D2DT03385B}, abstractNote={The synthesis and characterization of dinuclear ligand-to-ligand charge transfer complexes are described.}, journal={DALTON TRANSACTIONS}, author={Shultz, David A. A. and Stephenson, Riley and Kirk, Martin L. L.}, year={2023}, month={Jan} }
 @article{chen_yang_yadav_shultz_kirk_2023, title={Origin of Ferromagnetic Exchange Coupling in Donor-Acceptor Biradical Analogues of Charge-Separated Excited States}, volume={1}, ISSN={["1520-510X"]}, url={https://doi.org/10.1021/acs.inorgchem.2c02903}, DOI={10.1021/acs.inorgchem.2c02903}, abstractNote={A new donor-acceptor biradical complex, TpCum,MeZn(SQ-VD) (TpCum,MeZn+ = zinc(II) hydro-tris(3-cumenyl-5-methylpyrazolyl)borate complex cation; SQ = orthosemiquinone; VD = oxoverdazyl), which is a ground-state analogue of a charge-separated excited state, has been synthesized and structurally characterized. The magnetic exchange interaction between the S = 1/2 SQ and the S = 1/2 VD within the SQ-VD biradical ligand is observed to be ferromagnetic, with JSQ-VD = +77 cm-1 (H = -2JSQ-VDŜSQ·ŜVD) determined from an analysis of the variable-temperature magnetic susceptibility data. The pairwise biradical exchange interaction in TpCum,MeZn(SQ-VD) can be compared with that of the related donor-acceptor biradical complex TpCum,MeZn(SQ-NN) (NN = nitronyl nitroxide, S = 1/2), where JSQ-NN ≅ +550 cm-1. This represents a dramatic reduction in the biradical exchange by a factor of ∼7, despite the isolobal nature of the VD and NN acceptor radical SOMOs. Computations assessing the magnitude of the exchange were performed using a broken-symmetry density functional theory (DFT) approach. These computations are in good agreement with those computed at the CASSCF NEVPT2 level, which also reveals an S = 1 triplet ground state as observed in the magnetic susceptibility measurements. A combination of electronic absorption spectroscopy and CASSCF computations has been used to elucidate the electronic origin of the large difference in the magnitude of the biradical exchange coupling between TpCum,MeZn(SQ-VD) and TpCum,MeZn(SQ-NN). A Valence Bond Configuration Interaction (VBCI) model was previously employed to highlight the importance of mixing an SQSOMO → NNLUMO charge transfer configuration into the electronic ground state to facilitate the stabilization of the high-spin triplet (S = 1) ground state in TpCum,MeZn(SQ-NN). Here, CASSCF computations confirm the importance of mixing the pendant radical (e.g., VD, NN) LUMO (VDLUMO and NNLUMO) with the SOMO of the SQ radical (SQSOMO) for stabilizing the triplet, in addition to spin polarization and charge transfer contributions to the exchange. An important electronic structure difference between TpCum,MeZn(SQ-VD) and TpCum,MeZn(SQ-NN), which leads to their different exchange couplings, is the reduced admixture of excited states that promote ferromagnetic exchange into the TpCum,MeZn(SQ-VD) ground state, and the intrinsically weaker mixing between the VDLUMO and the SQSOMO compared to that observed for TpCum,MeZn(SQ-NN), where this orbital mixing is significant. The results of this comparative study contribute to a greater understanding of biradical exchange interactions, which are important to our understanding of excited-state singlet-triplet energy gaps, electron delocalization, and the generation of electron spin polarization in both the ground and excited states of (bpy)Pt(CAT-radical) complexes.}, journal={INORGANIC CHEMISTRY}, author={Chen, Ju and Yang, Jing and Yadav, Munendra and Shultz, David A. . and Kirk, Martin L.}, year={2023}, month={Jan} }
 @article{miller_shultz_mengell_kirk_wojtas_2023, title={Variation from closed-shell to open shell electronic structures in oligothiophene bis(dioxolene) complexes}, volume={10}, ISSN={["2041-6539"]}, url={https://doi.org/10.1039/D3SC02341A}, DOI={10.1039/D3SC02341A}, abstractNote={A symmetry-based model that explicitly includes the bridge fragment is used to explain a continuum of electronic structures for Kekulé-type biradicals.}, journal={CHEMICAL SCIENCE}, author={Miller, Paul D. and Shultz, David A. and Mengell, Joshua and Kirk, Martin L. and Wojtas, Lukasz}, year={2023}, month={Oct} }
 @article{kirk_shultz_hewitt_est_2022, title={Excited State Exchange Control of Photoinduced Electron Spin Polarization in Electronic Ground States}, volume={1}, ISSN={["1948-7185"]}, url={https://doi.org/10.1021/acs.jpclett.1c03491}, DOI={10.1021/acs.jpclett.1c03491}, abstractNote={Ground-state electron spin polarization (ESP) is generated in radical elaborated (bpy)Pt(CAT-NN) and (bpy)Pt(CAT-p-Me2PhMe2-NN) (bpy = 5,5'-di-tert-butyl-2,2'-bipyridine, CAT = 3-tert-butylcatecholate, p-Ph = para-phenylene, NN = nitronylnitroxide). Photoexcitation produces an exchange-coupled, three-spin, charge-separated doublet 2S1 (S = chromophore excited spin singlet configuration) excited state that rapidly decays to a 2T1 (T = chromophore excited spin triplet configuration) excited state. The SQ-bridge-NN bond torsions affect the magnitude of the excited state exchange interaction (JSQ-NN), which determines the 2T1-4T1 energy gap. Ground state ESP is dependent on the magnitude of JSQ-NN, and we postulate that this results from differences in 2T1 and 4T1 state mixing. Mechanisms that lead to the rapid transfer of the excited state ESP to the ground state are discussed. Although subnanosecond 2T1 state lifetimes are measured optically in solution, the ground state ESP decays very slowly at 20 K and is observable for more than a millisecond.}, journal={JOURNAL OF PHYSICAL CHEMISTRY LETTERS}, author={Kirk, Martin L. and Shultz, David A. and Hewitt, Patrick and Est, Art}, year={2022}, month={Jan} }
 @article{kirk_shultz_hewitt_chen_est_2022, title={Excited State Magneto-Structural Correlations Related to Photoinduced Electron Spin Polarization}, volume={7}, ISSN={["1520-5126"]}, url={https://doi.org/10.1021/jacs.2c03490}, DOI={10.1021/jacs.2c03490}, abstractNote={Photoinduced electron spin polarization (ESP) is reported in the ground state of a series of complexes consisting of an organic radical (nitronylnitroxide, NN) covalently attached to a donor-acceptor chromophore either directly or via para-phenylene bridges substituted with 0-4 methyl groups. These molecules represent a class of chromophores that undergo visible light excitation to produce an initial exchange-coupled, three-spin [bpy•-, CAT•+ (= semiquinone, SQ) and NN•], charge-separated doublet 2S1 (S = chromophore spin singlet configuration) excited state that rapidly decays by magnetic exchange-enhanced internal conversion to a 2T1 (T = chromophore excited spin triplet configuration) state. The 2T1 state equilibrates with chromophoric and NN radical-derived excited states, resulting in absorptive ESP of the recovered ground state, which persists for greater than a millisecond and can be measured by low-temperature time-resolved electron paramagnetic resonance spectroscopy. The magnitude of the ground state ESP is found to correlate with the excited state magnetic exchange interaction between the CAT+• and NN• radicals, which in turn is controlled by the structure of the bridge fragment.}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Hewitt, Patrick and Chen, Ju and Est, Art van der}, year={2022}, month={Jul} }
 @article{kirk_shultz_marri_hewitt_van der est_2022, title={Single-Photon-Induced Electron Spin Polarization of Two Exchange-Coupled Stable Radicals}, volume={144}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/jacs.2c09680}, DOI={10.1021/jacs.2c09680}, abstractNote={Transient electron paramagnetic resonance spectroscopy has been used to probe photoinduced electron spin polarization of a stable exchange-coupled organic biradical in a Pt(II) complex comprising 4,4'-di-tert-butyl-2,2'-bipyridine (bpy) and 3,6-bis(ethynyl-para-phenyl-nitronyl nitroxide)-o-catecholate (CAT(o-C≡C-Ph-NN)2). Photoexcitation results in four unpaired spins in excited states of this complex, with spins being localized on each of the two radicals, CAT•+ and bpy•-. The four spins are all exchange-coupled in these excited states, and an off-diagonal matrix element in the CAT•+-NN exchange allows for exchange-enhanced intersystem crossing to the 3T1a state, which possesses (bpy•-)Pt(CAT•+) chromophoric triplet character. Fast mixing between this 3T1a state and thermally accessible excited LL'CT state(s) followed by fast relaxation provides spin polarization of the exchange-coupled NN radicals in the 3S0 ground state of the complex. Our results demonstrate that well-defined quantum states of a ground-state biradical can be initialized with single-photon excitation and have the potential for further spin manipulation directed toward quantum information science applications.}, number={46}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Marri, Anil Reddy and Hewitt, Patrick and van der Est, Art}, year={2022}, month={Nov}, pages={21005–21009} }
 @article{kirk_shultz_hewitt_stasiw_chen_est_2021, title={Chromophore-radical excited state antiferromagnetic exchange controls the sign of photoinduced ground state spin polarization}, volume={9}, ISSN={["2041-6539"]}, DOI={10.1039/d1sc02965g}, abstractNote={A change in the sign of the ground state electron spin polarization (ESP) is reported in complexes where an organic radical (nitronylnitroxide, NN) is covalently attached to a donor–acceptor chromophoreviatwo differentmeta-phenylene bridges.}, journal={CHEMICAL SCIENCE}, author={Kirk, Martin L. and Shultz, David A. and Hewitt, Patrick and Stasiw, Daniel E. and Chen, Ju and Est, Art}, year={2021}, month={Sep} }
 @article{leroy_francisco_shepherd_warren_saunders_shultz_raithby_pinheiro_2021, title={Controlled Light and Temperature Induced Valence Tautomerism in a Cobalt-o-Dioxolene Complex}, volume={60}, ISSN={["1520-510X"]}, url={https://doi.org/10.1021/acs.inorgchem.1c00638}, DOI={10.1021/acs.inorgchem.1c00638}, abstractNote={The mononuclear cobalt complex of 3,5-di-tert-butylcathecolate and cyan-pyridine (Co(diox)2(4-CN-py)2) is a very versatile compound that displays valence tautomerism (VT) in the solid state, which is induced by temperature, light, and hard X-rays, and modulated by solvent in the crystal lattice. In our work, we used single crystal X-ray diffraction as a probe for the light-induced VT in solid state and demonstrate the controlled use of hard X-rays via attenuation to avoid X-ray-induced VT interconversion. We report photoinduced VT in benzene solvated crystals of Co(diox)2(4-CN-py)2 illuminated with blue 450 nm light at 30 K with a very high yield (80%) of metastable hs-CoII states, and we also show evidence of the de-excitation of these photoinduced metastable states using red 660 nm light. Such high-yield light-induced VT had never been experimentally observed in molecular crystals of cobalt tautomers, proving that the 450 nm light illumination is triggering a chain of events that leads to the ls-CoIII to hs-CoII interconversion.}, number={12}, journal={INORGANIC CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Leroy, Ludmila and Francisco, Thiago M. and Shepherd, Helena J. and Warren, Mark R. and Saunders, Lucy K. and Shultz, David A. and Raithby, Paul R. and Pinheiro, Carlos B.}, year={2021}, month={Jun}, pages={8665–8671} }
 @article{hewitt_shultz_kirk_2021, title={Magnetic Exchange Coupling through the Nonalternant Cyclopentadienyl pi-System of Ferrocene}, volume={23}, ISSN={["1523-7052"]}, url={https://doi.org/10.1021/acs.orglett.1c02982}, DOI={10.1021/acs.orglett.1c02982}, abstractNote={Electronic and magnetic coupling through nonalternant π-systems is an area of intense interest in photonics and molecular electronics research, yet relatively little is known regarding coupling through nonalternant π-systems. Herein we present magnetic exchange coupling in two semiquinone-based biradicals: 1,3-SQ2Fc has two semiquinone radicals attached to the one- and three-positions of the same cyclopentadienyl ligand (a nonalternant π-system) of ferrocene, whereas 1,1'-SQ2Fc has one semiquinone radical attached to each of the two cyclopentadienyl ligands of ferrocene.}, number={21}, journal={ORGANIC LETTERS}, publisher={American Chemical Society (ACS)}, author={Hewitt, Patrick and Shultz, David A. and Kirk, Martin L.}, year={2021}, month={Nov}, pages={8235–8239} }
 @article{kirk_shultz_chen_hewitt_daley_paudel_der est_2021, title={Metal Ion Control of Photoinduced Electron Spin Polarization in Electronic Ground States}, volume={143}, ISSN={["1520-5126"]}, url={https://doi.org/10.1021/jacs.1c04149}, DOI={10.1021/jacs.1c04149}, abstractNote={Both the sign and intensity of photoinduced electron spin polarization (ESP) in the electronic ground state doublet (2S0/D0) of chromophore-radical complexes can be controlled by changing the nature of the metal ion. The complexes consist of an organic radical (nitronyl nitroxide, NN) covalently attached to a donor-acceptor chromophore via a m-phenylene bridge, (bpy)M(CAT-m-Ph-NN) (1) (bpy = 4,4'-di-tert-butyl-2,2'-bipyridine, M = PdII (1-Pd) or PtII (1-Pt), CAT = 3-tert-butylcatecholate, m-Ph = meta-phenylene). In both complexes, photoexcitation with visible light produces an initial exchange-coupled, three-spin (bpy•-, CAT•+ = semiquinone (SQ), and NN•), charge-separated doublet 2S1 (S = chromophore excited spin singlet configuration) excited state that rapidly decays to the ground state via a 2T1 (T = chromophore excited spin triplet configuration) state. This process is not expected to be spin selective, and only very weak emissive ESP is found for 1-Pd. In contrast, strong absorptive ESP is generated in 1-Pt. It is postulated that zero-field-splitting-induced transitions between the chromophoric 2T1 and 4T1 states (1-Pd and 1-Pt) and spin-orbit-induced transitions between 2T1 and NN-based quartet states (1-Pt) account for the differences in polarization.}, number={28}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Chen, Ju and Hewitt, Patrick and Daley, David and Paudel, Sangita and Der Est, Art}, year={2021}, month={Jul}, pages={10519–10523} }
 @article{hewitt_shultz_kirk_2021, title={Rules for Magnetic Exchange in Azulene-Bridged Biradicals: Quo Vadis?}, volume={86}, ISSN={["1520-6904"]}, url={https://doi.org/10.1021/acs.joc.1c02085}, DOI={10.1021/acs.joc.1c02085}, abstractNote={Electronic coupling through organic bridges facilitates magnetic exchange interactions and controls electron transfer and single-molecule device electron transport. Electronic coupling through alternant π-systems (e.g., benzene) is better understood than the corresponding coupling through nonalternant π-systems (e.g., azulene). Herein, we examine the structure, spectroscopy, and magnetic exchange coupling in two biradicals (1,3-SQ2Az and 1,3-SQ-Az-NN; SQ = the zinc(II) complex of spin-1/2 semiquinone radical anion, NN = spin-1/2 nitronylnitroxide; Az = azulene) that possess nonalternant azulene π-system bridges. The SQ radical spin density in both molecules is delocalized into the Az π-system, while the NN spin is effectively localized onto the five-atom ONCNO π-system of NN radical. The spin distributions and interactions are probed by EPR spectroscopy and magnetic susceptibility measurements. We find that J = +38 cm-1 for 1,3-SQ2Az and J = +9 cm-1 for 1,3-SQ-Az-NN (H=-2JS^SQ·S^SQorNN). Our results highlight the differences in exchange coupling mediated by azulene compared to exchange coupling mediated by alternant π-systems.}, number={21}, journal={JOURNAL OF ORGANIC CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Hewitt, Patrick and Shultz, David A. and Kirk, Martin L.}, year={2021}, month={Nov}, pages={15577–15587} }
 @misc{wasielewski_forbes_frank_kowalski_scholes_yuen-zhou_baldo_freedman_goldsmith_goodson_et al._2020, title={Exploiting chemistry and molecular systems for quantum information science}, volume={4}, ISSN={["2397-3358"]}, DOI={10.1038/s41570-020-0200-5}, abstractNote={The power of chemistry to prepare new molecules and materials has driven the quest for new approaches to solve problems having global societal impact, such as in renewable energy, healthcare and information science. In the latter case, the intrinsic quantum nature of the electronic, nuclear and spin degrees of freedom in molecules offers intriguing new possibilities to advance the emerging field of quantum information science. In this Perspective, which resulted from discussions by the co-authors at a US Department of Energy workshop held in November 2018, we discuss how chemical systems and reactions can impact quantum computing, communication and sensing. Hierarchical molecular design and synthesis, from small molecules to supramolecular assemblies, combined with new spectroscopic probes of quantum coherence and theoretical modelling of complex systems, offer a broad range of possibilities to realize practical quantum information science applications.}, number={9}, journal={NATURE REVIEWS CHEMISTRY}, author={Wasielewski, Michael R. and Forbes, Malcolm D. E. and Frank, Natia L. and Kowalski, Karol and Scholes, Gregory D. and Yuen-Zhou, Joel and Baldo, Marc A. and Freedman, Danna E. and Goldsmith, Randall H. and Goodson, Theodore, III and et al.}, year={2020}, month={Sep}, pages={490–504} }
 @article{hewitt_shultz_2020, title={In Search of Stable, High-Spin Polymers}, volume={51}, ISSN={["1613-7507"]}, url={https://doi.org/10.1007/s00723-020-01293-z}, DOI={10.1007/s00723-020-01293-z}, number={11}, journal={APPLIED MAGNETIC RESONANCE}, author={Hewitt, Patrick and Shultz, David A.}, year={2020}, month={Nov}, pages={1331–1341} }
 @article{shultz_kirk_zhang_stasiw_wang_yang_habel-rodriguez_stein_sommer_2020, title={Spectroscopic Signatures of Resonance Inhibition Reveal Differences in Donor–Bridge and Bridge–Acceptor Couplings}, volume={142}, url={https://doi.org/10.1021/jacs.0c00326}, DOI={10.1021/jacs.0c00326}, abstractNote={The torsional dependence of the ground state magnetic exchange coupling (J), and the corresponding electronic coupling matrix element (HDA) for eight transition metal complexes possessing donor-acceptor (D-A) biradical ligands is presented. These biradical ligands are comprised of an S= ½ metal semiquinone (SQ) donor and an S = ½ nitronylnitroxide (NN) acceptor, which are coupled to each other via para-phenylene, methyl-substituted para-phenylenes, or bicyclo[2.2.2]octane ring. The observed trends in electronic absorption- and resonance Raman spectral features are in accord with reduction in electronic and magnetic coupling between D and A units within the framework of our valence bond configuration interaction model. Moreover, our spectroscopic results highlight different orbital mechanisms that modulate coupling in these complexes, that is not manifest in the ferromagnetic JSQ-B-NN values. The work provides new detailed insight into the effects of torsional rotations which contribute to inhomogeneities in experimentally determined exchange couplings, electron transfer rates, and electron transport conductance measurements.}, number={10}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Kirk, Martin L. and Zhang, Jinyuan and Stasiw, Daniel E. and Wang, Guangbin and Yang, Jing and Habel-Rodriguez, Diana and Stein, Benjamin W. and Sommer, Roger D.}, year={2020}, month={Mar}, pages={4916–4924} }
 @article{kirk_dangi_habel-rodriguez_yang_shultz_zhang_2020, title={Transferrable property relationships between magnetic exchange coupling and molecular conductance}, volume={11}, ISSN={["2041-6539"]}, DOI={10.1039/d0sc04350h}, abstractNote={Calculated conductance through Aun–S–Bridge–S–Aun constructs are compared to experimental magnetic exchange coupling parameters in TpCum,MeZn(SQ–Bridge–NN) complexes, where SQ = semiquinone radical and NN = nitronylnitroxide radical.}, number={42}, journal={CHEMICAL SCIENCE}, author={Kirk, Martin L. and Dangi, Ranjana and Habel-Rodriguez, Diana and Yang, Jing and Shultz, David A. and Zhang, Jinyuan}, year={2020}, month={Nov}, pages={11425–11434} }
 @article{stein_dickie_nedungadi_brook_shultz_kirk_2019, title={Long-range spin dependent delocalization promoted by the pseudo Jahn-Teller effect}, volume={151}, ISSN={["1089-7690"]}, url={https://doi.org/10.1063/1.5128117}, DOI={10.1063/1.5128117}, abstractNote={Strong spin-dependent delocalization (double exchange) was previously demonstrated for the complexes, NN-Bridge-SQ-Coiii(py)2Cat-Bridge-NN (where NN = S = 12 nitronylnitroxide, Bridge = 1,4-phenylene and single bond, SQ = S = 12 orthobenzosemiquinone, Coiii = low-spin d6 cobalt 3+, and Cat = diamagnetic catecholate). The mixed-valent S = 12 SQ-Coiii-Cat triad results in ferromagnetic alignment of localized (pinned) NN spins which are ∼22 Å apart (Bridge = Ph). Herein, we report similar ferromagnetic coupling of localized verdazyl (Vdz) radical spins. The origin of the magnetic exchange results from a second order vibronic effect (pseudo Jahn-Teller effect) in [Vdz-diox-Ru(py)2-diox-Vdz]0, which possesses a diamagnetic [diox-Ru-diox]0 triad by virtue of strong antiferromagnetic SQ-Ruiii exchange.}, number={20}, journal={JOURNAL OF CHEMICAL PHYSICS}, author={Stein, Benjamin W. and Dickie, Diane A. and Nedungadi, Sachin and Brook, David J. R. and Shultz, David A. and Kirk, Martin L.}, year={2019}, month={Nov} }
 @article{tichnell_daley_stein_shultz_kirk_danilov_2019, title={Wave Function Control of Charge-Separated Excited-State Lifetimes}, volume={141}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/JACS.8B13011}, DOI={10.1021/JACS.8B13011}, abstractNote={Control of excited-state processes is crucial to an increasing number of important device technologies that include displays, photocatalysts, solar energy conversion devices, photovoltaics, and photonics. However, the manipulation and control of electronic excited-state lifetimes and properties continue to be a challenge for molecular scientists. Herein, we present the results of ground-state and transient absorption spectroscopies as they relate to magnetic exchange control of excited-state lifetimes. We describe a novel mechanism for controlling these excited-state lifetimes that involves varying the magnetic exchange interaction between a stable organic radical and the unpaired electrons present in the open-shell configuration of a charge-separated excited state. Specifically, we show that the excited-state lifetime can be controlled in a predictable manner based on an a priori knowledge of the pairwise magnetic exchange interactions between excited-state spins. These magnetic exchange couplings affect the excited-state electronic structure in a manner that introduces variable degrees of spin forbiddenness into the nonradiative decay channel between the excited state and the electronic ground state.}, number={9}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Tichnell, Christopher R. and Daley, David R. and Stein, Benjamin W. and Shultz, David A. and Kirk, Martin L. and Danilov, Evgeny O.}, year={2019}, month={Feb}, pages={3986–3992} }
 @article{stein_tichnell_chen_shultz_kirk_2018, title={Excited State Magnetic Exchange Interactions Enable Large Spin Polarization Effects}, volume={140}, ISSN={["0002-7863"]}, url={https://doi.org/10.1021/jacs.7b11397}, DOI={10.1021/jacs.7b11397}, abstractNote={Excited state processes involving multiple electron spin centers are crucial elements for both spintronics and quantum information processing. Herein, we describe an addressable excited state mechanism for precise control of electron spin polarization. This mechanism derives from excited state magnetic exchange couplings that occur between the electron spins of a photogenerated electron-hole pair and that of an organic radical. The process is initiated by absorption of a photon followed by ultrafast relaxation within the excited state spin manifold. This leads to dramatic changes in spin polarization between excited states of the same multiplicity. Moreover, this photoinitiated spin polarization process can be "read" spectroscopically using a magnetooptical technique that is sensitive to the excited state electron spin polarizations and allows for the evaluation of wave functions that give rise to these polarizations. This system is unique in that it requires neither intersystem crossing nor magnetic resonance techniques to create dynamic spin-polarization effects in molecules.}, number={6}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={Stein, Benjamin W. and Tichnell, Christopher R. and Chen, Ju and Shultz, David A. and Kirk, Martin L.}, year={2018}, month={Feb}, pages={2221–2228} }
 @article{yang_kersi_richers_giles_dangi_stein_feng_tichnell_shultz_kirk_2018, title={Ground State Nuclear Magnetic Resonance Chemical Shifts Predict Charge-Separated Excited State Lifetimes}, volume={57}, ISSN={["1520-510X"]}, url={https://doi.org/10.1021/acs.inorgchem.8b02087}, DOI={10.1021/acs.inorgchem.8b02087}, abstractNote={Dichalcogenolene platinum(II) diimine complexes, (LE,E')Pt(bpy), are characterized by charge-separated dichalcogenolene donor (LE,E') → diimine acceptor (bpy) ligand-to-ligand charge transfer (LL'CT) excited states that lead to their interesting photophysics and potential use in solar energy conversion applications. Despite the intense interest in these complexes, the chalcogen dependence on the lifetime of the triplet LL'CT excited state remains unexplained. Three new (LE,E')Pt(bpy) complexes with mixed chalcogen donors exhibit decay rates that are dominated by a spin-orbit mediated nonradiative pathway, the magnitude of which is proportional to the anisotropic covalency provided by the mixed-chalcogen donor ligand environment. This anisotropic covalency is dramatically revealed in the 13C NMR chemical shifts of the donor carbons that bear the chalcogens and is further probed by S K-edge XAS. Remarkably, the NMR chemical shift differences also correlate with the spin-orbit matrix element that connects the triplet excited state with the ground state. Consequently, triplet LL'CT excited state lifetimes are proportional to both functions, demonstrating that specific ground state NMR chemical shifts can be used to evaluate spin-orbit coupling contributions to excited state lifetimes.}, number={21}, journal={INORGANIC CHEMISTRY}, publisher={American Chemical Society (ACS)}, author={Yang, Jing and Kersi, Dominic K. and Richers, Casseday P. and Giles, Logan J. and Dangi, Ranjana and Stein, Benjamin W. and Feng, Changjian and Tichnell, Christopher R. and Shultz, David A. and Kirk, Martin L.}, year={2018}, month={Nov}, pages={13470–13476} }
 @article{yang_zhang_duan_2017, title={Effect of hydrologic alteration on the community succession of macrophytes at xiangyang site, hanjiang river, china}, journal={Scientifica}, author={Yang, N. and Zhang, Y. H. and Duan, K.}, year={2017} }
 @article{francisco_gee_shepherd_warren_shultz_raithby_pinheiro_2017, title={Hard X-ray-Induced Valence Tautomeric Interconversion in Cobalt-o-Dioxolene Complexes}, volume={8}, ISSN={1948-7185}, url={http://dx.doi.org/10.1021/ACS.JPCLETT.7B01794}, DOI={10.1021/ACS.JPCLETT.7B01794}, abstractNote={Valence tautomeric interconversion (VTI) is a reversible process occurring in metal complexes in which an intramolecular metal-ligand electron transfer is accompanied by a change of metal ion spin state, creating two switchable electronic states (redox isomers). Herein, we describe the low-temperature, 30-100 K, single-crystal study of the [Co(diox)2(4-CN-py)2]·benzene complex (1) (diox = 3,5-di-t-butylsemiquinonate (SQ•-) and/or 3,5-di-t-butylcatecholate (Cat2-) radical; 4-CN-py = 4-cyano-pyridine) using hard synchrotron X-ray radiation with different intensities. We demonstrate for the first time that hard X-rays can induce VTI, and that the interconversion molar fraction is dependent on both intensity and exposure time. This in turn shows that X-rays, as a probe, might be altering the very nature of many structures under investigation at low temperatures, and consequently their properties. Our findings add new perspectives to VTI studies and might be of significant interest to the entire community investigating photoresponsive complexes.}, number={19}, journal={The Journal of Physical Chemistry Letters}, publisher={American Chemical Society (ACS)}, author={Francisco, Thiago M. and Gee, William J. and Shepherd, Helena J. and Warren, Mark R. and Shultz, David A. and Raithby, Paul R. and Pinheiro, Carlos B.}, year={2017}, month={Sep}, pages={4774–4778} }
 @article{kirk_shultz_zhang_dangi_ingersol_yang_finney_sommer_wojtas_2017, title={Heterospin biradicals provide insight into molecular conductance and rectification}, volume={8}, ISSN={2041-6520 2041-6539}, url={http://dx.doi.org/10.1039/C7SC00073A}, DOI={10.1039/C7SC00073A}, abstractNote={Properties of two isomeric triplet ground state biradical molecules, which serve as constant-bias analogs of single-molecule electronic devices, are described and experimental results are compared with transport calculations in a device geometry.}, number={8}, journal={Chemical Science}, publisher={Royal Society of Chemistry (RSC)}, author={Kirk, Martin L. and Shultz, David A. and Zhang, Jinyuan and Dangi, Ranjana and Ingersol, Laura and Yang, Jing and Finney, Nathaniel S. and Sommer, Roger D. and Wojtas, Lukasz}, year={2017}, pages={5408–5415} }
 @inproceedings{shultz_2017, title={Wavefunction Control of Charge-Separated Excited State Spin Polarization and Lifetimes}, author={Shultz, D}, year={2017}, month={Sep} }
 @article{steenbock_shultz_kirk_herrmann_2016, title={Influence of Radical Bridges on Electron Spin Coupling}, volume={121}, ISSN={1089-5639 1520-5215}, url={http://dx.doi.org/10.1021/ACS.JPCA.6B07270}, DOI={10.1021/ACS.JPCA.6B07270}, abstractNote={Increasing interactions between spin centers in molecules and molecular materials is a desirable goal for applications such as single-molecule magnets for information storage or magnetic metal-organic frameworks for adsorptive separation and targeted drug delivery and release. To maximize these interactions, introducing unpaired spins on bridging ligands is a concept used in several areas where such interactions are otherwise quite weak, in particular, lanthanide-based molecular magnets and magnetic metal-organic frameworks. Here, we use Kohn-Sham density functional theory to study how much the ground spin state is stabilized relative to other low-lying spin states by creating an additional spin center on the bridge for a series of simple model compounds. The di- and triradical structures consist of nitronyl nitroxide (NNO) and semiquinone (SQ) radicals attached to a meta-phenylene(R) bridge (where R = -NH•/-NH2, -O•/OH, -CH2•/CH2). These model compounds are based on a fully characterized SQ-meta-phenylene-NNO diradical with moderately strong antiferromagnetic coupling. Replacing closed-shell substituents CH3 and NH2 with their radical counterparts CH2• and NH• leads to an increase in stabilization of the ground state with respect to other low-lying spin states by a factor of 3-6, depending on the exchange-correlation functional. For OH compared with O• substituents, no conclusions can be drawn as the spin state energetics depend strongly on the functional. This could provide a basis for constructing sensitive test systems for benchmarking theoretical methods for spin state energy splittings. Reassuringly, the stabilization found for a potentially synthesizable complex (up to a factor of 3.5) is in line with the simple model systems (where a stabilization of up to a factor of 6.2 was found). Absolute spin state energy splittings are considerably smaller for the potentially stable system than those for the model complexes, which points to a dependence on the spin delocalization from the radical substituent on the bridge.}, number={1}, journal={The Journal of Physical Chemistry A}, publisher={American Chemical Society (ACS)}, author={Steenbock, Torben and Shultz, David A. and Kirk, Martin L. and Herrmann, Carmen}, year={2016}, month={Dec}, pages={216–225} }
 @article{ribeiro_stasiw_pattison_raithby_shultz_pinheiro_2016, title={Toward Controlling the Solid State Valence Tautomeric Interconversion Character by Solvation}, volume={16}, ISSN={["1528-7505"]}, DOI={10.1021/acs.cgd.6b00159}, abstractNote={Crystals of [Co(diox)2(4-NO2-py)2] (1) and [Co(diox)2(4-CN-py)2] (2) where diox are the o-dioxolene 3,5-di-t-butylsemiquinonate (SQ•–) and/or 3,5-di-t-butylcatecholate (Cat2–) ions, 4-NO2-py is 4-nitro-pyridine, 4-CN-py is 4-cyano-pyridine, are among the few known crystals presenting both thermally induced and photoinduced ls-[M+3(SQ•–)(Cat2–)] ↔ hs-[M2+(SQ•–)2] valence tautomeric interconversion (VTI). In 2, the thermal-induced VTI is cooperative, characterizing an abrupt conversion, and in 1 it is noncooperative. In this work, crystals of [Co(diox)2(4-NO2-py)2]·benzene (1BZ), [Co(diox)2(4-NO2-py)2]·toluene (1TL), [Co(diox)2(4-CN-py)2]·benzene (2BZ), and [Co(diox)2(4-CN-py)2]·toluene (2TL) have been prepared and analyzed by single crystal X-ray diffraction in order to investigate how solvation modulates thermally induced VTI. Crystallographic data were also successfully used together with the two-state equilibrium equation to estimate ΔH° and ΔS° VTI thermodynamic parameters. The solvate crystals, like t...}, number={4}, journal={CRYSTAL GROWTH & DESIGN}, author={Ribeiro, Marcos A. and Stasiw, Daniel E. and Pattison, Philip and Raithby, Paul R. and Shultz, David A. and Pinheiro, Carlos B.}, year={2016}, month={Apr}, pages={2385–2393} }
 @article{stasiw_zhang_wang_dangi_stein_shultz_kirk_wojtas_sommer_2015, title={Determining the Conformational Landscape of a and pi Coupling Using para-Phenylene and "Aviram-Ratner" Bridges}, volume={137}, ISSN={["0002-7863"]}, DOI={10.1021/jacs.5b04629}, abstractNote={The torsional dependence of donor-bridge-acceptor (D-B-A) electronic coupling matrix elements (H(DA), determined from the magnetic exchange coupling, J) involving a spin SD = 1/2 metal semiquinone (Zn-SQ) donor and a spin S(A) = 1/2 nitronylnitroxide (NN) acceptor mediated by the σ/π-systems of para-phenylene and methyl-substituted para-phenylene bridges and by the σ-system of a bicyclo[2.2.2]octane (BCO) bridge are presented and discussed. The positions of methyl group(s) on the phenylene bridge allow for an experimentally determined evaluation of conformationally dependent (π) and conformationally independent (σ) contributions to the electronic and magnetic exchange couplings in these D-B-A biradicals at parity of D and A. The trend in the experimental magnetic exchange couplings are well described by CASSCF calculations. The torsional dependence of the pairwise exchange interactions are further illuminated in three-dimensional, "Ramachandran-type" plots that relate D-B and B-A torsions to both electronic and exchange couplings. Analysis of the magnetic data shows large variations in magnetic exchange (J ≈ 1-175 cm(-1)) and electronic coupling (H(DA) ≈ 450-6000 cm(-1)) as a function of bridge conformation relative to the donor and acceptor. This has allowed for an experimental determination of both the σ- and π-orbital contributions to the exchange and electronic couplings.}, number={29}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Stasiw, Daniel E. and Zhang, Jinyuan and Wang, Guangbin and Dangi, Ranjana and Stein, Benjamin W. and Shultz, David A. and Kirk, Martin L. and Wojtas, Lukasz and Sommer, Roger D.}, year={2015}, month={Jul}, pages={9222–9225} }
 @inproceedings{shultz_2015, title={Donor-Acceptor Biradicals in Ground and Excited States}, author={Shultz, D}, year={2015}, month={Jun} }
 @inproceedings{shultz_2015, title={Semiquinone-Containing Polymers}, author={Shultz, D}, year={2015}, month={Jun} }
 @inproceedings{shultz_2015, title={Superexchange Contributions to Quantum Interference Effects in Donor-Acceptor Biradicals}, author={Shultz, D}, year={2015}, month={Mar} }
 @article{tichnell_shultz_popescu_sokirniy_boyle_2015, title={Synthesis, Characterization, and Photophysical Studies of an Iron(III) Catecholate-Nitronylnitroxide Spin-Crossover Complex}, volume={54}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.5b00298}, abstractNote={The synthesis and characterization of an Fe(III) catecholate-nitronylnitroxide (CAT-NN) complex (1-NN) that undergoes Fe(III) spin-crossover is described. Our aim is to determine whether the intraligand exchange coupling of the semiquinone-nitronylnitroxide Fe(II)(SQ-NN) excited state resulting from irradiation of the CAT → Fe(III) LMCT band would affect either the intrinsic photophysics or the iron spin-crossover event when compared to the complex lacking the nitronylnitroxide radical (1). X-ray crystallographic analysis provides bond lengths consistent with a ferric catecholate charge distribution. Mössbauer spectroscopy clearly demonstrates Fe(III) spin-crossover, hyperfine couplings, and a weak ferromagnetic Fe(III)-CAT-NN exchange, and spin-crossover is corroborated by variable-temperature magnetic susceptibility and electronic absorption studies. To explore the effect of the NN radical on photophysical processes, we conducted room-temperature transient absorption experiments. Upon excitation of the ligand-to-metal charge transfer band, an Fe(II)SQ state is populated and most likely undergoes fast intersystem crossing to the ligand field manifold, where it rapidly decays into a metastable low-spin Fe(III)CAT state, followed by repopulation of the high-spin Fe(III)CAT ground state. The decay components of 1-NN are slightly faster than those obtained for 1, perhaps due to the higher number of microstates present within the LMCT and LF manifolds for 1-NN. Although the effects of the NN radical are manifest in neither the spin-crossover nor the photophysics, our results lay the groundwork for future studies.}, number={9}, journal={INORGANIC CHEMISTRY}, author={Tichnell, Christopher R. and Shultz, David A. and Popescu, Codrina V. and Sokirniy, Ivan and Boyle, Paul D.}, year={2015}, month={May}, pages={4466–4474} }
 @inproceedings{stasiw_shultz_2014, title={Conformational Dependence of Electronic- and Exchange Coupling}, author={Stasiw, D and Shultz, S.}, year={2014} }
 @article{kirk_shultz_stasiw_habel-rodriguez_stein_boyle_2014, title={Correction to “Electronic and Exchange Coupling in a Cross-Conjugated D–B–A Biradical: Mechanistic Implications for Quantum Interference Effects”}, volume={136}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/JA500972C}, DOI={10.1021/JA500972C}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionORIGINAL ARTICLEThis notice is a correctionCorrection to “Electronic and Exchange Coupling in a Cross-Conjugated D–B–A Biradical: Mechanistic Implications for Quantum Interference Effects”Martin L. Kirk*, David A. Shultz*, Daniel E. Stasiw, Diana Habel-Rodriguez, Benjamin Stein, and Paul D. BoyleCite this: J. Am. Chem. Soc. 2014, 136, 10, 4090Publication Date (Web):February 28, 2014Publication History Published online28 February 2014Published inissue 12 March 2014https://doi.org/10.1021/ja500972cCopyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views959Altmetric-Citations1LEARN 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 PDF (119 KB) Get e-Alerts Get e-Alerts}, number={10}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Stasiw, Daniel E. and Habel-Rodriguez, Diana and Stein, Benjamin and Boyle, Paul D.}, year={2014}, month={Feb}, pages={4090–4090} }
 @article{kirk_shultz_stasiw_lewis_wang_brannen_sommer_boyle_2014, title={Correction to “Superexchange Contributions to Distance Dependence of Electron Transfer/Transport: Exchange and Electronic Coupling in Oligo(para-Phenylene)- and Oligo(2,5-Thiophene)-Bridged Donor–Bridge–Acceptor Biradical Complexes”}, volume={136}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/JA500971X}, DOI={10.1021/JA500971X}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to “Superexchange Contributions to Distance Dependence of Electron Transfer/Transport: Exchange and Electronic Coupling in Oligo(para-Phenylene)- and Oligo(2,5-Thiophene)-Bridged Donor–Bridge–Acceptor Biradical Complexes”Martin L. Kirk*, David A. Shultz*, Daniel E. Stasiw, Geoffry F. Lewis, Guangbin Wang, Candice L. Brannen, Roger D. Sommer, and Paul D. BoyleCite this: J. Am. Chem. Soc. 2014, 136, 10, 4089Publication Date (Web):February 28, 2014Publication History Published online28 February 2014Published inissue 12 March 2014https://doi.org/10.1021/ja500971xCopyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1194Altmetric-Citations1LEARN 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 PDF (121 KB) Get e-Alertsclose Get e-Alerts}, number={10}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Stasiw, Daniel E. and Lewis, Geoffry F. and Wang, Guangbin and Brannen, Candice L. and Sommer, Roger D. and Boyle, Paul D.}, year={2014}, month={Feb}, pages={4089–4089} }
 @inproceedings{shultz_2014, title={Correlations of Electron Spin Exchange- and Electronic Coupling in Metal Complexes of Donor-Bridge-Acceptor Biradical Ligands}, author={Shultz, D.}, year={2014} }
 @article{yang_kersi_giles_stein_feng_tichnell_shultz_kirk_2014, title={Ligand Control of Donor–Acceptor Excited-State Lifetimes}, volume={53}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/IC500217Y}, DOI={10.1021/IC500217Y}, abstractNote={Transient absorption and emission spectroscopic studies on a series of diimineplatinum(II) dichalcogenolenes, LPtL', reveal charge-separated dichalcogenolene → diimine charge-transfer (LL'CT) excited-state lifetimes that display a remarkable and nonperiodic dependence on the heteroatoms of the dichalcogenolene ligand. Namely, there is no linear relationship between the observed lifetimes and the principle quantum number of the E donors. The results are explained in terms of heteroatom-dependent singlet-triplet (S-T) energy gaps and anisotropic covalency contributions to the M-E (E = O, S, Se) bonding scheme that control rates of intersystem crossing. For the dioxolene complex, 1-O,O', E(T2) > E(S1) and rapid nonradiative decay occurs from S1 to S0. However, E(T2) ≤ E(S1) for the heavy-atom congeners, and this provides a mechanism for rapid intersystem crossing. Subsequent internal conversion to T1 in 3-S,S produces a long-lived, emissive triplet. The two LPtL' complexes with mixed chalcogen donors and 5-Se,Se show lifetimes intermediate between those of 1-O,O' and 3-S,S.}, number={10}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Yang, Jing and Kersi, Dominic K. and Giles, Logan J. and Stein, Benjamin W. and Feng, Changjian and Tichnell, Christopher R. and Shultz, David A. and Kirk, Martin L.}, year={2014}, month={Apr}, pages={4791–4793} }
 @article{shultz_kirk_2014, title={Molecular spintronics: a web themed issue}, volume={50}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/C4CC90186J}, DOI={10.1039/C4CC90186J}, abstractNote={The emerging field of Molecular Spintronics (Spin Transport Electronics) combines key elements of electron transport and electron spin. The effects of electron spin introduce new and interesting complexities to the molecular electronics field, and provide an attractive platform for the exploitation of new opportunities toward the control of electron transfer and charge transport phenomena, spin delocalization, spin polarization, molecular rectification and spin injection. The exquisite degree of molecular-level synthetic control in the design of organic, inorganic and hybrid organic/ inorganic molecules and materials allows researchers to manipulate openshell electronic structure in ways that are impossible for solid-state materials. When ‘‘magnetic molecules’’ are used in conjunction with solid-state semiconducting and magnetic materials, novel behaviors can be envisioned and are now being realized. Although these are still the ‘‘early days’’ for this nascent field, important advances in molecular spintronics are progressing at a remarkable pace. This is evidenced by the number of high-profile research reports that have recently been published, including the critical works featured in this webthemed collection. The feature articles and communications in this collection highlight remarkable achievements, developments and future prospects in the molecular spintronics field. Significant contributions focus on spin polarization effects, dynamic spin density distribution, spin-dependent molecular rectification, spin-valves, coherent spin manipulation, exchange interactions between ferromagnetic substrates and paramagnetic molecules, donor–acceptor biradicals, and applied-field effects on radical-pair intersystem crossing. A host of cutting edge spectroscopic and magnetic techniques have been used to gain important insight into the complex interplay between electron spin and electron transfer/transport, which form the basis of molecular spintronics research. a Department of Chemistry, NC State University, Raleigh, NC 27695-8204, USA. E-mail: David_Shultz@ncsu.edu b Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, NM 87131-0001, USA. E-mail: mkirk@unm.edu}, number={56}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Shultz, David A. and Kirk, Martin L.}, year={2014}, pages={7401} }
 @inproceedings{tichnell_shultz_2014, title={Radical-Mediated Excited State Processes of Donor-Acceptor Chromophores}, author={Tichnell, C and Shultz, D.}, year={2014} }
 @article{ribeiro_stasiw_shultz_pattison_raithby_pinheiro_2014, title={Towards Controlling the Valance Tautomer Interconversion Character by Solvation}, volume={70}, ISSN={2053-2733}, url={http://dx.doi.org/10.1107/s2053273314087476}, DOI={10.1107/s2053273314087476}, abstractNote={Valence tautomers are bi-stable functional molecular materials in which it is observed charge transference between redox active ligands and a metallic center followed by the change of spin of the metal. Valence tautomerism (VT) interconversion is entropically driven and induced by external stimuli such as irradiation by light and soft X-rays and/or changes in temperature and pressure. VT interconversion is also associated with remarkable variations in optical and magnetic properties and and can be modulated with slight chemical changes [1]. Typical examples of valence tautomers are coordination compounds of Co and o-dioxolenes ligands [2]. Crystals of the [Co(diox)(4-X-py)2], where diox = 3,5-di-t-butylcatecholate/3,5-di-t-butylsemiquinonate, X=CN/NO2, py= pyridine, were initially studied with respect to low spin (LS) to high spin (HS) thermo and photoinduced VT interconversion. It was reported that [Co(diox)(4-CN-py)2] crystals become HS–Co3+ at temperatures below 110 K with cooperative VT interconversion whereas [Co(diox)(4-NO2-py)2] crystals present non cooperative VT interconversion [3]. Toluene and benzene solvates of [Co(diox)(4-NO2-py)2 and [Co(diox)(4-CN-py)2 have been prepared to investigate further the solvation effects on the VT interconversion properties. Analysis of the single crystal X-ray diffraction data obtained during cooling and heating at temperatures ranging from 293 K to 90 K indicated that [Co(diox)(4-CN-py)2] toluene and benzene as well as [Co(diox)(4-NO2-py)2].toluene solvate crystals undergo into non cooperative VT interconversion. The [Co(diox)(4-NO2-py)2].benzene crystal show a highly cooperative VT interconversion with a pronounced hysteresis. Intermolecular interactions between inlayer [Co(diox)(4-X-py)2] molecules are responsible for the VT interconversion in all compounds, however the VT interconversion cooperativity seems to be related with the strength of the Car–H...Odiox interactions and with the correspondent Co–Co separation. Thus solvation plays a key role in the definition of the VT interconversion nature. Acknowledgments: FAPEMIG, CNPq and CAPES grant 10030-12-3.}, number={a1}, journal={Acta Crystallographica Section A Foundations and Advances}, publisher={International Union of Crystallography (IUCr)}, author={Ribeiro, Marcos and Stasiw, Daniel and Shultz, David and Pattison, Philip and Raithby, Paul and Pinheiro, Carlos}, year={2014}, month={Aug}, pages={C1252–C1252} }
 @article{kirk_shultz_stasiw_habel-rodriguez_stein_boyle_2013, title={Electronic and Exchange Coupling in a Cross-Conjugated D–B–A Biradical: Mechanistic Implications for Quantum Interference Effects}, volume={135}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/JA405354X}, DOI={10.1021/JA405354X}, abstractNote={A combination of variable-temperature EPR spectroscopy, electronic absorption spectroscopy, and magnetic susceptibility measurements have been performed on Tp(Cum,Me)Zn(SQ-m-Ph-NN) (1-meta) a donor-bridge-acceptor (D-B-A) biradical that possesses a cross-conjugated meta-phenylene (m-Ph) bridge and a spin singlet ground state. The experimental results have been interpreted in the context of detailed bonding and excited-state computations in order to understand the excited-state electronic structure of 1-meta. The results reveal important excited-state contributions to the ground-state singlet-triplet splitting in this cross-conjugated D-B-A biradical that contribute to our understanding of electronic coupling in cross-conjugated molecules and specifically to quantum interference effects. In contrast to the conjugated isomer, which is a D-B-A biradical possessing a para-phenylene bridge, admixture of a single low-lying singly excited D → A type configuration into the cross-conjugated D-B-A biradical ground state makes a negligible contribution to the ground-state magnetic exchange interaction. Instead, an excited state formed by a Ph-NN (HOMO) → Ph-NN (LUMO) one-electron promotion configurationally mixes into the ground state of the m-Ph bridged D-A biradical. This results in a double (dynamic) spin polarization mechanism as the dominant contributor to ground-state antiferromagnetic exchange coupling between the SQ and NN spins. Thus, the dominant exchange mechanism is one that activates the bridge moiety via the spin polarization of a doubly occupied orbital with phenylene bridge character. This mechanism is important, as it enhances the electronic and magnetic communication in cross-conjugated D-B-A molecules where, in the case of 1-meta, the magnetic exchange in the active electron approximation is expected to be J ~ 0 cm(-1). We hypothesize that similar superexchange mechanisms are common to all cross-conjugated D-B-A triads. Our results are compared to quantum interference effects on electron transfer/transport when cross-conjugated molecules are employed as the bridge or molecular wire component and suggest a mechanism by which electronic coupling (and therefore electron transfer/transport) can be modulated.}, number={39}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Stasiw, Daniel E. and Habel-Rodriguez, Diana and Stein, Benjamin and Boyle, Paul D.}, year={2013}, month={Sep}, pages={14713–14725} }
 @article{pronschinske_bruce_lewis_chen_calzolari_buongiorno-nardelli_shultz_you_dougherty_2013, title={Iron(ii) spin crossover films on Au(111): scanning probe microscopy and photoelectron spectroscopy}, volume={49}, ISSN={1359-7345 1364-548X}, url={http://dx.doi.org/10.1039/C3CC44904A}, DOI={10.1039/C3CC44904A}, abstractNote={The growth of films of [H2B(pz)2]Fe(ii)(bpy) on Au(111) is characterized from the bilayer film to multilayer film regime. Scanning tunneling microscopy shows a transition from a well-ordered, uniform bilayer film to a poorly-ordered film at larger thicknesses. Previous local tunneling spectroscopy and conductance mapping in bilayer films permit the identification of coexisting molecular spin-states at all temperatures. New ultraviolet photoelectron spectroscopy is consistent with this picture and in agreement with the density of states calculated by density functional theory. In thicker films with a polycrystalline morphology, evidence for a more bulk-like change in spin composition as a function of temperature is obtained by observing the reduction in intensity of Fe 2p core level satellites in X-ray photoelectron spectra.}, number={89}, journal={Chemical Communications}, publisher={Royal Society of Chemistry (RSC)}, author={Pronschinske, Alex and Bruce, Robert C. and Lewis, Geoff and Chen, Yifeng and Calzolari, Arrigo and Buongiorno-Nardelli, Marco and Shultz, David A. and You, Wei and Dougherty, Daniel B.}, year={2013}, pages={10446} }
 @article{pronschinske_chen_lewis_shultz_calzolari_buongiorno nardelli_dougherty_2013, title={Modification of Molecular Spin Crossover in Ultrathin Films}, volume={13}, ISSN={1530-6984 1530-6992}, url={http://dx.doi.org/10.1021/nl304304e}, DOI={10.1021/nl304304e}, abstractNote={Scanning tunneling microscopy and local conductance mapping show spin-state coexistence in bilayer films of Fe[(H2Bpz2)2bpy] on Au(111) that is independent of temperature between 131 and 300 K. This modification of bulk behavior is attributed in part to the unique packing constraints of the bilayer film that promote deviations from bulk behavior. The local density of states measured for different spin states shows that high-spin molecules have a smaller transport gap than low-spin molecules and are in agreement with density functional theory calculations.}, number={4}, journal={Nano Letters}, publisher={American Chemical Society (ACS)}, author={Pronschinske, Alex and Chen, Yifeng and Lewis, Geoffrey F. and Shultz, David A. and Calzolari, Arrigo and Buongiorno Nardelli, Marco and Dougherty, Daniel B.}, year={2013}, month={Mar}, pages={1429–1434} }
 @inproceedings{shultz_2013, title={Preliminary Photophysical Studies on Metal Complexes of Catecholate Nitronyl-Nitroxides: Exploring the Effects of Tunable Exchange Couplings on Charge-Separated Excited States}, author={Shultz, D.}, year={2013} }
 @article{kirk_shultz_stasiw_lewis_wang_brannen_sommer_boyle_2013, title={Superexchange Contributions to Distance Dependence of Electron Transfer/Transport: Exchange and Electronic Coupling in Oligo(para-Phenylene)- and Oligo(2,5-Thiophene)-Bridged Donor–Bridge–Acceptor Biradical Complexes}, volume={135}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/JA4081887}, DOI={10.1021/JA4081887}, abstractNote={The preparation and characterization of three new donor-bridge-acceptor biradical complexes are described. Using variable-temperature magnetic susceptibility, EPR hyperfine coupling constants, and the results of X-ray crystal structures, we evaluate both exchange and electronic couplings as a function of bridge length for two quintessential molecular bridges: oligo(para-phenylene), β = 0.39 Å(-1) and oligo(2,5-thiophene), β = 0.22 Å(-1). This report represents the first direct comparison of exchange/electronic couplings and distance attenuation parameters (β) for these bridges. The work provides a direct measurement of superexchange contributions to β, with no contribution from incoherent hopping. The different β values determined for oligo(para-phenylene) and oligo(2,5-thiophene) are due primarily to the D-B energy gap, Δ, rather than bridge-bridge electronic couplings, H(BB). This is supported by the fact that the H(BB) values extracted from the experimental data for oligo(para-phenylene) (H(BB) = 11,400 cm(-1)) and oligo(2,5-thiophene) (12,300 cm(-1)) differ by <10%. The results presented here offer unique insight into the intrinsic molecular factors that govern H(DA) and β, which are important for understanding the electronic origin of electron transfer and electron transport mediated by molecular bridges.}, number={45}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Stasiw, Daniel E. and Lewis, Geoffrey F. and Wang, Guangbin and Brannen, Candice L. and Sommer, Roger D. and Boyle, Paul D.}, year={2013}, month={Nov}, pages={17144–17154} }
 @article{kirk_shultz_2013, title={Transition metal complexes of donor–acceptor biradicals}, volume={257}, ISSN={0010-8545}, url={http://dx.doi.org/10.1016/J.CCR.2012.07.007}, DOI={10.1016/J.CCR.2012.07.007}, abstractNote={The nature of the electronic coupling in transition metal Donor–Acceptor and Donor–Bridge–Acceptor systems has become a subject of interest in the last decade due to the importance of electronic coupling in molecular electronics. Here we review the synthesis, structure, magnetism, and spectroscopy of donor–acceptor biradicals as they pertain to understanding the electronic origins and magnitude of the electronic coupling matrix element that figures prominently in electron transfer (transport). Stable D–A systems may be thought of as ground state analogues of charge separated states generated in photoinduced electron transfer processes and as model systems for understanding single molecule mediated electron transport between biased nanoelectrodes. The strong coupling (adiabatic) regime will be covered in this review as well as the methodology for probing the magnitude of the electronic coupling in this limit. D–A biradicals can facilitate long-range ferromagnetic exchange between localized spins mediated by delocalized electrons, and this is a new phenomenon in molecular systems. The use of the VBCI approach to develop a complete electronic structure description of strong electronic coupling in D–A and D–B–A biradicals, the origin of long-range biradical ferromagnetic exchange, and the relationship of these biradicals to molecular electronic materials will form the basis of the review.}, number={1}, journal={Coordination Chemistry Reviews}, publisher={Elsevier BV}, author={Kirk, Martin L. and Shultz, David A.}, year={2013}, month={Jan}, pages={218–233} }
 @article{calzolari_chen_lewis_dougherty_shultz_buongiorno nardelli_2012, title={Complex Materials for Molecular Spintronics Applications: Cobalt Bis(dioxolene) Valence Tautomers, from Molecules to Polymers}, volume={116}, ISSN={1520-6106 1520-5207}, url={http://dx.doi.org/10.1021/jp3099895}, DOI={10.1021/jp3099895}, abstractNote={Using first principles calculations, we predict a complex multifunctional behavior in cobalt bis(dioxolene) valence tautomeric compounds. Molecular spin-state switching is shown to dramatically alter electronic properties and corresponding transport properties. This spin state dependence has been demonstrated for technologically relevant coordination polymers of valence tautomers as well as for novel conjugated polymers with valence tautomeric functionalization. As a result, these materials are proposed as promising candidates for spintronic devices that can couple magnetic bistability with novel electrical and spin conduction properties. Our findings pave the way to the fundamental understanding and future design of active multifunctional organic materials for spintronics applications.}, number={43}, journal={The Journal of Physical Chemistry B}, publisher={American Chemical Society (ACS)}, author={Calzolari, Arrigo and Chen, Yifeng and Lewis, Geoffrey F. and Dougherty, Daniel B. and Shultz, David and Buongiorno Nardelli, Marco}, year={2012}, month={Oct}, pages={13141–13148} }
 @inproceedings{schultz_2012, title={Donor-Bridge-Acceptor Structure-Property Relationships in Metal Complexes of Semiquinone-Bridge-Nitronyl Nitroxide Ligands}, author={Schultz, D}, year={2012} }
 @inproceedings{schultz_2012, place={Germany}, title={Evaluating Bridge-Dependent Electronic Coupling via Exchange Couplings and Hyperfine Coupling Constants in Metal Complexes of Donor-Bridge-Acceptor Biradicals}, publisher={University of Hamburg}, author={Schultz, D}, year={2012}, month={Sep} }
 @misc{schultz_2012, title={Photoresponsive Cobalt Bis(dioxolene) Valence Tautomer Complexes and Their Utility in Novel Molecular Spintronics Devices}, author={Schultz, D}, year={2012}, month={Sep} }
 @article{kirk_shultz_depperman_habel-rodriguez_schmidt_2012, title={Spectroscopic Studies of Bridge Contributions to Electronic Coupling in a Donor-Bridge-Acceptor Biradical System}, volume={134}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja300233a}, DOI={10.1021/ja300233a}, abstractNote={Variable-temperature electronic absorption and resonance Raman spectroscopies are used to probe the excited state electronic structure of Tp(Cum,Me)Zn(SQ-Ph-NN) (1), a donor-bridge-acceptor (D-B-A) biradical complex and a ground state analogue of the charge-separated excited state formed in photoinduced electron transfer reactions. Strong electronic coupling mediated by the p-phenylene bridge stabilizes the triplet ground state of this molecule. Detailed spectroscopic and bonding calculations elucidate key bridge distortions that are involved in the SQ(π)(SOMO) → NN-Ph (π*)(LUMO) D → A charge transfer (CT) transition. We show that the primary excited state distortion that accompanies this CT is along a vibrational coordinate best described as a symmetric Ph(8a) + SQ(in-plane) linear combination and underscores the dominant role of the phenylene bridge fragment acting as an electron acceptor in the D-B-A charge transfer state. Our results show the importance of the phenylene bridge in promoting (1) electron transfer in D-Ph-A systems and (2) electron transport in biased electrode devices that employ a 1,4-phenylene linkage. We have also developed a relationship between the spin density on the acceptor, as measured via the isotropic NN nitrogen hyperfine interaction, and the strength of the D → A interaction given by the magnitude of the electronic coupling matrix element, H(ab).}, number={18}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Depperman, Ezra C. and Habel-Rodriguez, Diana and Schmidt, Robert D.}, year={2012}, month={May}, pages={7812–7819} }
 @article{sloop_shultz_marcus_shepler_2011, title={Linear free-energy relationships in semiquinone species and their Mn(II) and Cu(II) complexes}, volume={25}, ISSN={0894-3230}, url={http://dx.doi.org/10.1002/poc.1878}, DOI={10.1002/poc.1878}, abstractNote={Linear free‐energy relationships for a series of functionalized semiquinone ligands and their MnII‐ and CuIIhydro‐tris(3‐cumenyl‐5‐methylpyrazolyl) borate complexes were examined. Quinone–semiquinone cycle half‐wave reduction potentials and semiquinone hydrogen hyperfine coupling constants (aH) were determined and their correlation with Hammett σ parameters reported. A new σ parameter, σaH, has been proposed. MnII and CuII metal complex metal–ligand charge transfer and n → π* UV transitions were found to be modulated by substituents. Satisfactory Hammett correlations between UV transitions and various σ values have been determined and compared in a number of instances. Copyright © 2011 John Wiley & Sons, Ltd.}, number={2}, journal={Journal of Physical Organic Chemistry}, publisher={Wiley}, author={Sloop, Joseph C. and Shultz, David A. and Marcus, Mithra Beikmohamadi and Shepler, Benjamin}, year={2011}, month={Jun}, pages={101–109} }
 @article{lee_lee_kim_bang_shultz_schmidt_forbes_lee_2011, title={Nitronyl Nitroxide Radicals as Organic Memory Elements with Both n- and p-Type Properties}, volume={50}, ISSN={1433-7851}, url={http://dx.doi.org/10.1002/anie.201004899}, DOI={10.1002/anie.201004899}, abstractNote={Organic molecules are being actively explored for use in logical devices, either as individual memory elements or as components embedded in small organic and polymeric materials. Conventional inorganic semiconductor devices are limited in terms of performance improvement owing to increased costs for device fabrication as well as physical limitations on minimum feature dimensions. Organic memory, however, is a possible substitute for both volatile and non-volatile memory devices. It has the advantages of facile tailoring through organic synthesis, simple device fabrication (even upon flexible substrates), and very low power consumption. Volatile organic memory is expected to be applied towards dynamic random access memory (DRAM), which typically requires a data refresh every few milliseconds, while non-volatile organic memory can be applied to read-only memory (ROM) and flash-type memory. Several types of organic and polymeric materials have been reported for this purpose, such as organic semiconductors, charge-transfer complexes (including redoxactive compounds), and metal-nanoparticle-dispersed thin films. Recently, a new type of organic memory has been added to this list, namely organic radical molecules (nitroxide radicals, NOC) that contain an unpaired electron that is capable of undergoing oxidation or reduction by applied bias voltages. In 1901, Piloty and Schwerin succeeded in the synthesis and isolation of porphyrexide, the first organic nitroxide. The most prominent member of this class of compounds is the 2,2,6,6-tetramethylpiperidine-N-oxyl radical (TEMPO). TEMPO and many other NO radicals belong to the category of persistent radicals. Since this pioneering work, the Nakahara group has reported the synthesis of a polymeric TEMPO radical derivative, poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate) (PTMA), for an organic radical battery. The research group of Nishide extended this work toward applications, such as radical batteries as cathode active materials, organic light-emitting diodes as holeinjection layers, and memory as p-type redox active materials. The TEMPO radical is easily oxidized to yield the corresponding oxoammonium salt, returning to the TEMPO radical by a p-type one-electron reduction. However, for the complete circuit of the organic semiconducting device using PTMA, an n-type redox active material as a partner to the p-type material is required. Some previously reported polymer-based organic radical memory devices required additional organic layers, such as an electron-accepting layer for n-type and even a metalparticle-dispersed dielectric layer for actuation of the organic memory device. While previous research into polymerbased organic radical memory has led to significant advances, for a complete organic radical memory circuit it is crucial to find new organic radical molecules that demonstrate switchability and present both pand n-type properties within the molecule. Also, new molecules can facilitate understanding of the origin of memory effects and whether that effect is induced by the organic radical alone or whether other environmental or chemical factors must be considered. Herein we report novel molecular radical memory behavior using a stable organic radical molecule. We have synthesized and characterized the nitronyl nitroxide (NN) radical molecule 2-(3’-tert-butyl-4’,5’-dimethoxymethoxybiphenyl-4-yl)-4,4,5,5-tetramethylimidazolidine-1-oxyl-3-oxide (NN-Ph-CatMOM2) [14] (see also the Supporting Information). The NN radical possesses one unpaired electron that is delocalized across the two equivalent N O groups (Scheme 1). Owing to delocalization, the oxidized and reduced states of the NN radicals were expected to be stabilized over a wide window of applied voltages, leading to a high switchability for the NN radical memory. The ability of the NN-Ph-CatMOM2 to act as both electron donor and acceptor was investigated by cyclic voltammetry (CV) and simultaneous electrochemical electron paramagnetic resonance (SEEPR) spectroscopy under an applied voltage. Cyclic voltammograms were [*] Dr. J. Lee, E. Lee, S. Kim, Dr. G. S. Bang, Prof. H. Lee NCRI, Center for Smart Molecular Memory Department of Chemistry, Sungkyunkwan University Suwon 440-746 (Republic of Korea) Fax: (+ 82)31-299-5934 E-mail: hyoyoung@skku.edu Prof. D. A. Shultz, Dr. R. D. Schmidt Department of Chemistry, North Carolina State University Raleigh, NC 27695-8204 (USA) Fax: (+ 1)919-515-8920 E-mail: david_shultz@ncsu.edu}, number={19}, journal={Angewandte Chemie International Edition}, publisher={Wiley}, author={Lee, Junghyun and Lee, Eunkyo and Kim, Sangkwan and Bang, Gyeong Sook and Shultz, David A. and Schmidt, Robert D. and Forbes, Malcolm D. E. and Lee, Hyoyoung}, year={2011}, month={Apr}, pages={4414–4418} }
 @article{sloop_shultz_coote_shepler_sullivan_kampf_boyle_2011, title={Synthesis of and structure-property relationships in zinc complexes of bis-metaphenylene semiquinone biradical species}, volume={25}, ISSN={0894-3230}, url={http://dx.doi.org/10.1002/poc.1917}, DOI={10.1002/poc.1917}, abstractNote={The design of novel, functionalized bis‐metaphenylene semiquinone (SQ) ligands and their corresponding metal complexes which combine conformational flexibility and electron‐withdrawing, electron‐donating, and conjugating substituents enable investigation of multiple structure–property relationships. Along these lines, we report the synthesis of three new bis(ZnII(SQ)TpCum,Me) complexes containing the bis‐metaphenylene coupling fragment. Using electron paramagnetic resonance spectroscopy, ab initio computations and superconducting quantum interference device magnetometry, we show how spin‐density is affected by the bis‐metaphenylene system substituents. Copyright © 2011 John Wiley & Sons, Ltd.}, number={4}, journal={Journal of Physical Organic Chemistry}, publisher={Wiley}, author={Sloop, Joseph C. and Shultz, David A. and Coote, Tashni and Shepler, Benjamin and Sullivan, Ubie and Kampf, Jeff W. and Boyle, Paul D.}, year={2011}, month={Aug}, pages={314–321} }
 @article{schmidt_shultz_martin_boyle_2010, title={Goldilocks Effect in Magnetic Bistability: Remote Substituent Modulation and Lattice Control of Photoinduced Valence Tautomerism and Light-Induced Thermal Hysteresis}, volume={132}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja101957c}, DOI={10.1021/ja101957c}, abstractNote={The thermal-induced and photoinduced valence tautomerism of a series of Co(dioxolene)(2)(4-X-py)(2) complexes (dioxolene = 3,5-di-tert-butylcatecholate or 3,5-di-tert-butylsemiquinonate; 4-X-py = 4-(X)pyridine, X = H (1), OMe (2), Me (3), CN (4), Br (5), NO(2) (6)) is described. The thermal valence tautomerism (ls-Co(III)(SQ)(Cat)(4-X-py)(2) <--> hs-Co(II)(SQ)(SQ)(4-X-py)(2)) is only observed for complexes 4, 5, and 6 where each is accompanied by a hysteresis loop of ca. 5 K. When a crystalline sample of 4-6 is held at 10 K in a SQUID magnetometer and irradiated with white light (lambda = 400-850 nm), the hs-Co(II) tautomer is formed. When the light source is removed, and the sample is slowly heated, the hs-Co(II) tautomer persists until ca. 90 K, approximately 40 K higher than the thermal stability of previously reported complexes. Heating and cooling the sample while maintaining irradiation results in the appearance of a new light-induced thermal hysteresis loop below 90 K (DeltaT = ca. 25 K). Below 50 K, the hs-Co(II) tautomer displays temperature-independent relaxation to the ls-Co(III) form, and above 50 K, the relaxation is thermally activated with an activation energy E(a) > ca. 1500 cm(-1). The coordination geometry (trans-pyridines), pyridine substitution, and crystal packing forces conspire to create the comparatively thermally stable photogenerated hs-Co(II) tautomer, thus providing an excellent handle for molecular and crystal engineering studies.}, number={17}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Schmidt, R. D. and Shultz, D. A. and Martin, J. D. and Boyle, P. D.}, year={2010}, month={May}, pages={6261–6273} }
 @article{kirk_shultz_habel-rodriguez_schmidt_sullivan_2010, title={Hyperfine Interaction, Spin Polarization, and Spin Delocalization as Probes of Donor-Bridge-Acceptor Interactions in Exchange-Coupled Biradicals}, volume={114}, ISSN={["1520-5207"]}, DOI={10.1021/jp102955j}, abstractNote={Computations and EPR spectroscopy are used to probe the spin distribution of donor-bridge-acceptor (D-B-A) biradical complexes: Tp(Cum,Me)Zn(SQ-NN) (1), Tp(Cum,Me)Zn(SQ-1,4-Ph-NN) (2), Tp(Cum,Me)Zn(SQ-2,5-TP-NN) (3), and Tp(Cum,Me)Zn(SQ-2,5-Xyl-NN) (4) (SQ = orthosemiquinone and NN = nitronylnitroxide). These complexes are ground-state analogs of the charge-separated excited states formed in photoinduced electron transfer reactions. The intraligand magnetic exchange interaction (J) in these complexes is mediated by the bridges and has been found to stabilize the triplet ground states of 1 and 2. Detailed spectroscopic and bonding calculations have been used to elucidate the role of the bridge fragment (B) and its conformation relative to donor (SQ) and acceptor (NN) on spin density distributions. The computed results correlate well with experimental nitrogen hyperfine coupling constants.}, number={45}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Kirk, Martin L. and Shultz, David A. and Habel-Rodriguez, Diana and Schmidt, Robert D. and Sullivan, Ubie}, year={2010}, month={Nov}, pages={14712–14716} }
 @article{schmidt_shultz_martin_2010, title={Magnetic Bistability in a Cobalt Bis(dioxolene) Complex: Long-Lived Photoinduced Valence Tautomerism}, volume={49}, ISSN={["1520-510X"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-77950273381&partnerID=MN8TOARS}, DOI={10.1021/ic901998p}, abstractNote={The thermal- and photoinduced valence tautomerism of a cobalt bis(dioxolene) complex is described. The thermal conversion is precipitous, complete within 10 K, and is accompanied by a 5 K hysteresis loop (107 K < T(1/2) < 112 K). Rapid thermal quenching (300 K --> 10 K in ca. 5 s) and photoinduced valence tautomerism result in trapping of the metastable Co(II)-state at low temperatures through intermolecular hydrogen bonding. This lattice stabilization results in unmatched kinetic and thermal stability for a valence tautomer from 10-50 K, with residual hs-Co(II) persisting until about 90 K.}, number={7}, journal={INORGANIC CHEMISTRY}, author={Schmidt, Robert D. and Shultz, David A. and Martin, James D.}, year={2010}, month={Apr}, pages={3162–3168} }
 @inproceedings{shultz_2010, title={Spin Dependent Internal Conversion}, author={Shultz, D.}, year={2010}, month={Oct} }
 @inproceedings{shultz_2009, title={Electronic Structure and Metal Complexes of Donor-Acceptor Biradicals}, author={Shultz, D}, year={2009} }
 @article{kirk_shultz_schmidt_habel-rodriguez_lee_lee_2009, title={Ferromagnetic Nanoscale Electron Correlation Promoted by Organic Spin-Dependent Delocalization}, volume={131}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja904648r}, DOI={10.1021/ja904648r}, abstractNote={We describe the electronic structure and the origin of ferromagnetic exchange coupling in two new metal complexes, NN-SQ-Co(III)(py)(2)Cat-NN (1) and NN-Ph-SQ-Co(III)(py)(2)Cat-Ph-NN (2) (NN = nitronylnitroxide radical, Ph = 1,4-phenylene, SQ = S = (1)/(2) semiquinone radical, Cat = S = 0 catecholate, and py = pyridine). Near-IR electronic absorption spectroscopy for 1 and 2 reveals a low-energy optical band that has been assigned as a Psi(u) --> Psi(g) transition involving bonding and antibonding linear combinations of delocalized dioxolene (SQ/Cat) valence frontier molecular orbitals. The ferromagnetic exchange interaction in 1 is so strong that only the high-spin quartet state (S(T) = (3)/(2)) is thermally populated at temperatures up to 300 K. The temperature-dependent magnetic susceptibility data for 2 reveals that an excited state spin doublet (S(T) = (1)/(2)) is populated at higher temperatures, indicating that the phenylene spacer modulates the magnitude of the magnetic exchange. The valence delocalization within the dioxolene dyad of 2 results in ferromagnetic alignment of two localized NN radicals separated by over 22 A. The ferromagnetic exchange in 1 and 2 results from a spin-dependent delocalization (double exchange type) process and the origin of this strong electron correlation has been understood in terms of a valence bond configuration interaction (VBCI) model. We show that ferromagnetic coupling promoted by organic mixed-valency provides keen insight into the ability of single molecules to communicate spin information over nanoscale distances. Furthermore, the strong interaction between the itinerant dioxolene electron and localized NN electron spins impacts our ability to understand the exchange interaction between delocalized electrons and pinned magnetic impurities in technologically important dilute magnetic semiconductor materials. The long correlation length (22 A) of the itinerant electron that mediates this coupling indicates that high-spin pi-delocalized organic molecules could find applications as nanoscale spin-polarized electron injectors and molecular wires.}, number={51}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Schmidt, Robert D. and Habel-Rodriguez, Diana and Lee, Hyoyoung and Lee, Junghyun}, year={2009}, month={Dec}, pages={18304–18313} }
 @inproceedings{schultz_2009, title={Part I: Photochemistry without Photons: Electron Transfer Parameters from Electronic Structure Studies of Donor-Acceptor Biradicals}, author={Schultz, D}, year={2009} }
 @article{schultz_2008, title={Donor-Acceptor Biradicals: From Analogs of Photoinduced Charge-Separated Excited States to Nanoscale Electron Correlation}, author={Schultz, D}, year={2008} }
 @inproceedings{schultz_2008, title={The Physical Organic Chemistry of Electron Spin Exchange Coupling}, author={Schultz, D}, year={2008} }
 @article{kirk_shultz_depperman_brannen_2007, title={Donor−Acceptor Biradicals as Ground State Analogues of Photoinduced Charge Separated States}, volume={129}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja065384t}, DOI={10.1021/ja065384t}, abstractNote={A Valence Bond Configuration Interaction (VBCI) model is used to relate the intraligand magnetic exchange interaction (J) to the electronic coupling matrix element (HAB) in Tp(Cum,MeZn)(SQNN), a compound that possesses a Donor-Acceptor (D-A) SemiQuinone-NitronylNitroxide (SQNN) biradical ligand. Within this framework, an SQ --> NN charge transfer state mixes with the ground state and stabilizes the spin triplet (S = 1). This charge-transfer transition is observed spectroscopically and probed using resonance Raman spectroscopy. In addition, the temperature-dependent electronic absorption spectrum of the Ni(II) complex, Tp(Cum,MeNi)(SQNN), has been studied. Exchange coupling between the S = 1 Ni(II) ion and S = 1 SQNN provides a mechanism for observing the formally spin-forbidden, ligand-based 3GC --> 1CTC transition. This provides a means of determining U, the mean GC --> CTC energy, and a one-center exchange integral, K(0). The experimental determination of J, U, and K(0) permits facile calculation of HAB, and we show that this methodology can be extended to determine the electronic coupling matrix element in related SQ-Bridge-NN molecules. As magnetic susceptibility measurements are easily acquired in the solid state, H(AB) may be effectively determined for single molecules in a known geometry, provided a crystal structure exists for the biradical complex. Thus, SQ-Bridge-NN molecules possess considerable potential for probing both geometric and electronic structure contributions to the magnitude of the electronic coupling matrix element associated with a given bridge fragment.}, number={7}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Kirk, Martin L. and Shultz, David A. and Depperman, Ezra C. and Brannen, Candice L.}, year={2007}, month={Feb}, pages={1937–1943} }
 @article{carlson_kuehl_ogallo_shultz_thompson_kirk_martin_john_morris_2007, title={Influence of Ligand Geometry in Bimetallic Ytterbocene Complexes of Bridging Bis(bipyridyl) Ligands}, volume={26}, ISSN={0276-7333 1520-6041}, url={http://dx.doi.org/10.1021/om061157o}, DOI={10.1021/om061157o}, abstractNote={Two new bimetallic complexes, [Cp*2Yb]2(μ-1,3-(2,2‘-bipyridyl)-5-tBu-C6H3) (1) and [Cp*2Yb]2(μ-1,4-(2,2‘-bipyridyl)-C6H4) (2), and their corresponding two-electron oxidation products [1]2+ and [2]2+ have been synthesized with the aim of determining the impact of the bridging ligand geometry on the electronic and magnetic properties of these materials. Electrochemistry, optical spectroscopy, and bulk susceptibility measurements all support a ground-state electronic configuration of the type [(f)13-(πa*)1-(πb*)1-(f)13]. Density functional theory calculations on the uncomplexed bridging ligands as doubly reduced species also indicate that the diradical electronic configuration is the lowest lying for both meta- and para-bis(bipyridyl) systems. The electrochemical and optical spectroscopic data indicate that the electronic coupling between the metal centers mediated by the diradical bridges is weak, as evidenced by the small separation of the metal-based redox couples and the similarity of the f−f transitions...}, number={17}, journal={Organometallics}, publisher={American Chemical Society (ACS)}, author={Carlson, Christin N. and Kuehl, Christopher J. and Ogallo, Linda and Shultz, David A. and Thompson, J. D. and Kirk, Martin L. and Martin, Richard L. and John, Kevin D. and Morris, David E.}, year={2007}, month={Aug}, pages={4234–4242} }
 @article{shultz_sloop_coote_beikmohammadi_kampf_boyle_2007, title={Substituent Effects on Exchange Coupling:  5-Aryl-Substituted Semiquinones and Their Complexes with MnIIand CuII}, volume={46}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/ic061807g}, DOI={10.1021/ic061807g}, abstractNote={A series of functionalized radical anion semiquinone (SQ-Ar) ligands and their MnII- and CuIIhydro-tris(3-cumenyl-5-methylpyrazolyl)borate (TpCum,MeMII) complexes were prepared and characterized. The semiquinone ligands have substituted phenyl rings (Ar = -C6H5NO2, -C6H5OMe, -C6H5-tert-Bu, etc.) attached to the SQ 5-position. Despite the "remoteness" of the phenyl ring substituents, the MII-SQ exchange parameters, J, were found to vary nearly 3-fold. Attempts to quantify the substituent effects on J are complicated by the fact that not all complexes could be structurally characterized. As such, substituent effects and phenyl-ring torsion angles could conspire to produce the observed variation in J values. Although there is no clear trend in the J values as a function of SQ substituent for the MnII complexes, for the CuII complexes, electron-withdrawing substituents on the phenyl ring have greater ferromagnetic J values than the CuII complexes of SQ ligands with electron-donating substituents. This trend suggests a FM contribution from MLCT excited states in the copper complexes.}, number={1}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Sloop, Joseph C. and Coote, Tashni-Ann and Beikmohammadi, Mithra and Kampf, Jeff and Boyle, Paul D.}, year={2007}, month={Jan}, pages={273–277} }
 @article{shultz_sloop_washington_2006, title={Design, Synthesis, and Properties of Conformationally Fixed Semiquinone Monoradical Species}, volume={71}, ISSN={0022-3263 1520-6904}, url={http://dx.doi.org/10.1021/jo061502j}, DOI={10.1021/jo061502j}, abstractNote={The design of novel, functionalized semiquinone (SQ) ligands which combine structural rigidity and electron-withdrawing, electron-donating, and electroneutral substituents enables investigation of multiple structure-property relationships and building blocks for new materials, including components of sensors, switches, and molecular spintronics. Along these lines, we report the synthesis of several new SQ ligands containing fused heterocyclic ring systems. Using both electron paramagnetic resonance spectroscopy and quantum chemical calculations, we show how spin density is affected by the fused ring system substituents.}, number={24}, journal={The Journal of Organic Chemistry}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Sloop, Joseph C. and Washington, Gary}, year={2006}, month={Nov}, pages={9104–9113} }
 @article{shultz_mussari_ramanathan_kampf_2006, title={Electron Spin−Spin Exchange Coupling Mediated by the Porphyrin π System}, volume={45}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/ic060209z}, DOI={10.1021/ic060209z}, abstractNote={The syntheses and electron paramagnetic resonance (EPR) spectral characterizations of porphyrins (1-3) substituted with two radical groups bound to trans-meso positions are described. One of these compounds, 3, has been studied by variable-temperature magnetic susceptibility and has been structurally characterized. Biradical porphyrin 3 is monoclinic, space group P2(1)/n, with a = 12.239(2) A, b = 17.819(3) A, c = 34.445(7) A, alpha = 90 degrees , beta = 97.466(3) degrees , gamma = 90 degrees , and Z = 2. The bis(nitroxide) porphyrins 1 and 2 exhibit fluid solution EPR spectra consistent with |J| >> |a|. No evidence was observed for conformational modulation of J by rotation about single bonds as shown by the lack of change of the EPR spectra as a function of temperature. The bis(semiquinone) porphyrin 3 exhibits frozen-solution EPR spectra with zero-field splitting and a Deltam(s) = 2 transition characteristic of a triplet state. The intensity of the Deltam(s) = 2 transition of 3 was measured as a function of temperature, and the data fit according to a singlet-triplet model to yield J(3,solution) = -75 cm(-1) (H = - 2Jŝ1.ŝ2). Polycrystalline samples of porphryin 3 were examined by variable-temperature magnetometry. The paramagnetic susceptibility data were fit using a modified Bleaney-Bowers equation to give J(3,solid) = -29 cm(-1) (H = - 2Jŝ(1).ŝ(2)). The antiferromagnetic J values are consistent with the pi topology of the porphyrin ring.}, number={15}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Mussari, Christopher P. and Ramanathan, Krishna Kumar and Kampf, Jeff W.}, year={2006}, month={Jul}, pages={5752–5759} }
 @article{beni_dei_shultz_sorace_2006, title={Ligand design modulates photoinduced properties of cobalt-dioxolene valence tautomers}, volume={428}, ISSN={["1873-4448"]}, DOI={10.1016/j.cplett.2006.07.054}, abstractNote={A cobalt(III)-polydioxolene polymer undergoing valence tautomeric interconversion was irradiated at cryogenic temperatures. Magnetic and EPR data suggest the occurrence of photoinduced VT interconversion, with a maximum degree of about 10%. The kinetics data evidence a larger amount of cooperativity than previously observed in simple monomer, a phenomenon that we attribute to the 1D nature of the system. In the range 9–40 K the relaxation time follows two different regimes, both temperature dependent. The small values of the activation energies suggest the existence of phonon assisted relaxation mechanisms based on a tunneling process involving the totalsymmetric breathing mode of the complex.}, number={4-6}, journal={CHEMICAL PHYSICS LETTERS}, author={Beni, Alessandra and Dei, Andrea and Shultz, David A. and Sorace, Lorenzo}, year={2006}, month={Sep}, pages={400–404} }
 @article{bin-salamon_brewer_depperman_franzen_kampf_kirk_kumar_lappi_peariso_preuss_et al._2006, title={Testing Bridge-Mediated Differences in Dinuclear Valence Tautomeric Behavior}, volume={45}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/ic060170y}, DOI={10.1021/ic060170y}, abstractNote={Two structurally characterized dinuclear valence tautomers are described. Cobalt ions are bridged by p- and m-phenylene units connected to 2,2'-bipyridines. X-ray crystal structures show that the molecules are in the [(Co(III))(Co(III))] forms at ca. 125 K, while spectroscopic studies show that both molecules can achieve the [(Co(II))(Co(II))] form above 400 K and confirm the [(Co(III))(Co(III))] form below 10 K. Magnetic susceptibility studies are also included. Our results highlight the necessity of studying both crystalline and amorphous samples to distinguish the effects of intrinsic electronic structure and intermolecular forces on valence tautomeric behavior.}, number={11}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Bin-Salamon, Sofi and Brewer, Scott H. and Depperman, Ezra C. and Franzen, Stefan and Kampf, Jeff W. and Kirk, Martin L. and Kumar, R. Krishna and Lappi, Simon and Peariso, Katrina and Preuss, Kathryn E. and et al.}, year={2006}, month={May}, pages={4461–4467} }
 @article{kirk_shultz_depperman_2005, title={Beyond the active-electron approximation: Origin of ferromagnetic exchange in donor-acceptor heterospin biradicals}, volume={24}, ISSN={["0277-5387"]}, DOI={10.1016/j.poly.2005.08.010}, abstractNote={The complex, (NNSQ)CuTpCum,Me, is comprised of three different spin carrying units. These three S = 1/2 sites are comprised of Cu(II), nitronyl nitroxide (NN), and 5-tert-butyl-semiquinone (SQ). Both the Cu(II)–SQ and SQ–NN pairwise interactions are strongly exchange coupled resulting an ST = 3/2 ground state due to ferromagnetic interactions. Low-temperature EPR spectroscopy confirms the ST = 3/2 ground state determined from magnetic susceptibility studies and indicates that the quartet is zero-field split by |D| ∼ 0.5 cm−1. We have probed the origin of the strong ferromagnetic exchange within the NNSQ heterospin biradical ligand by a combination of electronic absorption, and low-temperature magnetic circular dichroism spectroscopies. The origin of the strong intraligand NNSQ ferromagnetic exchange has been suggested to result from an intraligand charge transfer (ILCT) transition transition that possesses appreciable SQ π → NN π* charge transfer character. The magnitude of the ferromagnetic exchange has been related to the energy of this ILCT transition, the magnitude of the NN single site exchange integral, and the magnitude of the electronic coupling matrix element that connects the SQ SOMO with the NN LUMO.}, number={16-17}, journal={POLYHEDRON}, author={Kirk, ML and Shultz, DA and Depperman, EC}, year={2005}, month={Nov}, pages={2880–2884} }
 @article{bin-salamon_brewer_franzen_feldheim_lappi_shultz_2005, title={Supramolecular control of valence-tautomeric equilibrium on nanometer-scale gold clusters}, volume={127}, ISSN={["0002-7863"]}, DOI={10.1021/ja042520q}, abstractNote={This communication describes the preparation and characterization of a valence tautomer complex covalently attached to gold nanoparticles. Variable-temperature IR spectroscopy is used to determine the equilibrium thermodynamic parameters for the valence tautomerization. These results are compared with a nonsurface combined valence tautomer complex. The results show that surface confinement attenuates both DeltaH degrees and DeltaS degrees . We attribute these changes to a reduced accessible molecular surface area.}, number={15}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Bin-Salamon, S and Brewer, S and Franzen, S and Feldheim, DL and Lappi, S and Shultz, DA}, year={2005}, month={Apr}, pages={5328–5329} }
 @article{shultz_kumar_bin-salamon_kirk_2005, title={Valence tautomerization and exchange coupling in a cobalt-nitronylnitroxide-semiquinone complex}, volume={24}, ISSN={["0277-5387"]}, DOI={10.1016/j.poly.2005.03.016}, abstractNote={Abstract The synthesis, variable-temperature electronic absorption spectroscopy, magnetic susceptibility of a novel valence tautomer are presented, and thermodynamic parameters for the valence tautomeric equilibrium were determined. The dioxolene used is a semiquinone–nitronylnitroxide donor–acceptor ligand. Due to the ferromagnetic coupling inherent in the semiquinone–nitronylnitroxide donor–acceptor biradical, the Co III form of the valence tautomer may display an additional stabilization of the high-spin ground state resulting from valence delocalization. As such, this would represent a unique example of double exchange in an organic system.}, number={16-17}, journal={POLYHEDRON}, author={Shultz, DA and Kumar, RK and Bin-Salamon, S and Kirk, ML}, year={2005}, month={Nov}, pages={2876–2879} }
 @inproceedings{schultz_2004, title={Exchange Coupling in Paramagnetic Ligands}, author={Schultz, D}, year={2004} }
 @inproceedings{schultz_2004, place={Tsukuba, Japan}, title={New Valence Tautomeric Molecules and Materials}, author={Schultz, D}, year={2004} }
 @inproceedings{conformational modulation of both exchange and mixed-valency in cross-conjugated, open-shell molecules_2003, year={2003}, month={Sep} }
 @article{shultz_fico_lee_kampf_kirschbaum_pinkerton_boyle_2003, title={Mechanisms of Exchange Modulation in Trimethylenemethane-type Biradicals:  The Roles of Conformation and Spin Density}, volume={125}, ISSN={["0002-7863"]}, DOI={10.1021/ja037787o}, abstractNote={The molecular structures and magnetic properties of six dinitroxide biradicals are described. Five of the dinitroxides are trimethylenemethane-type (TMM-type) biradicals; that is, the intramolecular exchange parameter, J, is modulated by a carbon-carbon double bond. However, the efficacy of the carbon-carbon double bond as an exchange coupler is determined by the molecular conformation. Our results show that the exchange parameters correlate with phenyl-ring torsion angles (phi) via a simple Karplus-Conroy-type relation: J = 44 cos(2) phi - 17. Comparison of these results to those obtained for our isostructural series of bis(semiquinone) biradicals shows that both the magnitude of J and the resistance of ferromagnetic J to bond torsions is proportional to the spin density adjacent to the exchange coupler.}, number={50}, journal={Journal of the American Chemical Society}, author={Shultz, D.A. and Fico, R.M., Jr. and Lee, H. and Kampf, J.W. and Kirschbaum, K. and Pinkerton, A.A. and Boyle, P.D.}, year={2003}, pages={15426–15432} }
 @misc{feldheim_marinakos_shultz_2003, title={Nanoparticle composites and nanocapsules for guest encapsulation and methods for synthesizing same}, volume={6,602,932}, number={2003 Aug. 5}, publisher={Washington, DC: U.S. Patent and Trademark Office}, author={Feldheim, D. L. and Marinakos, S. M. and Shultz, D. A.}, year={2003} }
 @inproceedings{schultz_2003, title={New Valence Tautomeric Molecules and Materials}, author={Schultz, D}, year={2003} }
 @article{franzen_shultz_2003, title={New paradigm for design of high-spin organic molecules: The mechanism of spin-dependent delocalization in exchange-coupled, mixed-valent organic species}, volume={107}, ISSN={["1520-5215"]}, DOI={10.1021/jp0276000}, abstractNote={A theory is developed to describe the electronic structure of mixed-valent, exchange-coupled organic biradicals. The phenomena described are analogous to those of spin-dependent delocalization observed in binuclear inorganic complexes in the sense that coupling of delocalized hole states favors a triplet state over a singlet state. However, the mathematical description of the delocalization is quite similar to Kramers' treatment of antiferromagnetic and ferromagnetic terms in metal oxides (Physica 1934, 1, 182). There is a similarity in that a delocalized orbital in the mixed-valent biradical anion can play the role of oxide in conventional superexchange. As in Kramers' theory, there are two terms that result from the analysis, a second-order term and a third-order term. However, the significance of the terms is different for delocalized magnetic orbitals than for the metal-bridge-metal system considered by Kramers. The computational chemistry shows that the third-order ferromagnetic term dominates for large dihedral angles, in agreement with previous experimental results. The mechanism presented suggests a new paradigm for the design of high-spin organic molecules.}, number={21}, journal={JOURNAL OF PHYSICAL CHEMISTRY A}, author={Franzen, S and Shultz, DA}, year={2003}, month={May}, pages={4292–4299} }
 @inproceedings{schultz_2003, title={Orbital Control of Exchange Coupling in Organic Biradicals}, author={Schultz, D}, year={2003}, month={Nov} }
 @article{bencini_caneschi_dei_gatteschi_sangregorio_shultz_sorace_vaz_2003, title={Polyoxolenes may provide a tool for designing paramagnetic molecules with predetermined spin topologies}, volume={6}, ISSN={["1631-0748"]}, DOI={10.1016/S1631-0748(03)00120-6}, abstractNote={The development of the chemistry of transition metal complexes formed by o-semiquinonato radical ligands has provided a useful topic for learning how to use chemical methods for obtaining systems with predetermined magnetic properties. Similar complexes can be used as building blocks for assembling magnetically coupled networks with multidimensional extended topologies. The examples reported here show how an appropriate strategy in designing linked semiquinonates can be used to fix the magnetic properties of a collection of paramagnetic centres. To cite this article: A. Bencini et al., C. R. Chimie 6 (2003). Le développement de la chimie des complexes o-semiquinonato des métaux de transition a fourni des outils très utiles pour l’appréhension de méthodes chimiques visant à l’obtention de systèmes moléculaires présentant des propriétés magnétiques prédéterminées. Des complexes similaires peuvent être utilisés comme briques paramagnétiques pour assembler des réseaux multidimensionnels possédant des topologies étendues. Les exemples présentés montrent comment une stratégie appropriée à la conception de ligands peut être employée pour la détermination des propriétés magnétiques d’une série de centres paramagnétiques. Pour citer cet article : A. Bencini et al., C. R. Chimie 6 (2003).}, number={7}, journal={COMPTES RENDUS CHIMIE}, author={Bencini, A and Caneschi, A and Dei, A and Gatteschi, D and Sangregorio, C and Shultz, D and Sorace, L and Vaz, MGF}, year={2003}, month={Jul}, pages={663–676} }
 @article{shultz_2003, title={The donor-acceptor contributions to ferromagnetic exchange coupling in heterospin biradicals}, volume={22}, ISSN={["0277-5387"]}, DOI={10.1016/S0277-5387(03)00217-1}, abstractNote={Abstract Frontier orbital perturbation theory analysis provides insight into a donor–acceptor contribution to ferromagnetic exchange in biradicals having two, chemically distinct paramagnetic groups.}, number={14-17}, journal={POLYHEDRON}, author={Shultz, DA}, year={2003}, month={Jul}, pages={2423–2426} }
 @article{shultz_fico_bodnar_kumar_vostrikova_kampf_boyle_2003, title={Trends in exchange coupling for trimethylenemethane-type bis(semiquinone) biradicals and correlation of magnetic exchange with mixed valency for cross-conjugated systems}, volume={125}, ISSN={["0002-7863"]}, DOI={10.1021/ja0367849}, abstractNote={A magnetostructural correlation (conformational electron spin exchange modulation) within an isostructural series of biradical complexes is presented. X-ray crystal structures, variable-temperature electron paramagnetic resonance spectroscopy, zero-field splitting parameters, and variable-temperature magnetic susceptibility measurements were used to evaluate molecular conformation and electron spin exchange coupling in this series of molecules. Our combined results indicate that the ferromagnetic portion of the exchange couplings occurs via the cross-conjugated pi-systems, while the antiferromagnetic portion occurs through space and is equivalent to incipient bond formation. Thus, molecular conformation controls the relative amounts of ferro- and antiferromagnetic contributions to exchange coupling. In fact, the exchange parameter correlates with average semiquinone ring torsion angles via a Karplus-Conroy-type relation. Because of the natural connection between electron spin exchange coupling and electronic coupling related to electron transfer, we also correlate the exchange parameters in the biradical complexes to mixed valency in the corresponding quinone-semiquinone radical anions. Our results suggest that delocalization in the cross-conjugated, mixed-valent radical anions is proportional to the ferromagnetic contribution to the exchange coupling in the biradical oxidation states.}, number={38}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Shultz, DA and Fico, RM and Bodnar, SH and Kumar, RK and Vostrikova, KE and Kampf, JW and Boyle, PD}, year={2003}, month={Sep}, pages={11761–11771} }
 @article{shultz_vostrikova_bodnar_koo_whangbo_kirk_depperman_kampf_2003, title={Trends in metal-biradical exchange interaction for first-row M-II(nitronyl nitroxide-semiquinone) complexes}, volume={125}, ISSN={["0002-7863"]}, DOI={10.1021/ja020715x}, abstractNote={We report molecular structures and temperature-dependent magnetic susceptibility data for several new metal complexes of heterospin triplet ground-state biradical ligands. The ligands are comprised of both nitronyl-nitroxide (NN) and semiquinone (SQ) spin carriers. Five compounds are five-coordinate M(II) complexes (M = Mn, Co, Ni, Cu, and Zn), and one is a six-coordinate Ni(II) complex. Five compounds were structurally characterized. During copper complex formation a reaction with methanol occurs to form a unique methoxy-substituted SQ ring. Variable-temperature magnetic susceptibility studies are consistent with strong intraligand (NN-SQ and NN-PhSQ) ferromagnetic exchange coupling. For the five-coordinate Mn, Co, and Ni complexes, the S = 1 ligand is antiferromagnetically coupled to the metal. For both the five-coordinate Cu complex and the six-coordinate Ni complex, the ligand is ferromagnetically coupled to the metal spins in accordance with orbital symmetry arguments. Despite the low molecular symmetries, the predicted trend in metal-ligand exchange interactions is supported by spin dimer analysis based on extended Hückel calculations. For (NN-SQ)NiTp(Cum,Me)() (Tp(Cum,Me)() = hydro-tris(3-cumenyl-5-methylpyrazolyl)borate), an antisymmetric exchange term was required for the best fit of the magnetic susceptibility data. Antisymmetric exchange was less important for the other complexes due to inherently smaller Deltag. Finally, it is shown that intraligand exchange coupling is of paramount importance in stabilizing high-spin states of mixed metal-biradical complexes.}, number={6}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Shultz, DA and Vostrikova, KE and Bodnar, SH and Koo, HJ and Whangbo, MH and Kirk, ML and Depperman, EC and Kampf, JW}, year={2003}, month={Feb}, pages={1607–1617} }
 @article{caneschi_dei_mussari_shultz_sorace_vostrikova_2002, title={High-spin metal complexes containing a ferromagnetically coupled tris(semiquinone) ligand}, volume={41}, ISSN={["0020-1669"]}, DOI={10.1021/ic0106322}, abstractNote={The tris-bidentate ligand 1,3,5-tris(5'-tert-butyl-3',4'-dihydroxyphenyl)benzene ((TBCat)(3)Ph) was synthesized. The reaction of this molecule in basic solution with two paramagnetic acceptors, i.e., a nickel(II)minus signtetraazamacrocyclic ligand complex (Ni(CTH)) (CTH = dl-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) and manganese(II)-hydrotris[3-(4'-cumenyl)-5-methylpyrazolyl]borate (Mn(Tp(Cum,Me))), yielded two complexes whose analytical formulas are consistent with those of trinuclear complexes. Spectroscopic and magnetic measurements suggest that these derivatives contain divalent metal ions coordinated to the tris(semiquinone) form of the ligand. Analysis of the magnetic data shows that the pi-connectivity of the ligand enforces ferromagnetic coupling between the three semiquinone units of the molecule, giving rise to complexes with S = 9/2 (M = Ni(II)) and S = 6 (M = Mn(II)) ground states. The coupling within the tris(semiquinone) unit is quite large (J = -26 cm(-1) for the nickel(II) derivative and J = -40 cm(-1) for the manganese(II) one, using the general exchange Hamiltonian H = sigma J(ij)S(i)S(j)), and it is of the same order of magnitude as that observed in an analogous series of bis(semiquinone) complexes that we recently reported.}, number={5}, journal={INORGANIC CHEMISTRY}, author={Caneschi, A and Dei, A and Mussari, CP and Shultz, DA and Sorace, L and Vostrikova, KE}, year={2002}, month={Mar}, pages={1086–1092} }
 @inproceedings{schultz_2002, title={New Developments in Semiquinone Chemistry}, author={Schultz, D}, year={2002} }
 @inproceedings{shultz_2002, title={New Valence Tautomeric Materials}, author={Shultz, D.}, year={2002} }
 @article{shultz_bodnar_lee_kampf_incarvito_rheingold_2002, title={Singlet-triplet gap in triplet ground-state biradicals is modulated by substituent effects}, volume={124}, ISSN={["0002-7863"]}, DOI={10.1021/ja020154+}, abstractNote={Three S = 1 bis(semiquinone) complexes have been prepared. To ensure ferromagnetic intramolecular exchange coupling, the two semiquinones are attached 1,3 to a 5-substituted phenylene ring. The biradical complexes differ in their meta-substituents: 1-NMe(2)(), X = N,N-dimethylamino; 1-t-Bu, X = tert-butyl; 1-NO(2)(), X = nitro. All three structures have been determined by X-ray crystallography. Results of structural studies indicate that the biradical ligands of all three complexes have nearly identical conformations with average semiquinone ring torsions of 32 degrees +/- 2 degrees relative to the 5-substituted phenylene ring. The exchange parameter, J (Eta = -2JS(1).S(2)), ranges from +31.0 +/- 0.6 cm(-)(1) for 1-NO(2)() to +59.3 +/- 1.2 cm(-)(1) for 1-t-Bu, with J = +34.9 +/- 0.7 cm(-)(1) for 1-NMe(2)(). Since the conformations are nearly identical, the differences in exchange coupling parameter J are due to substituent effects. The experimental results are supported by Hückel theory arguments and previous computational work.}, number={34}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Shultz, DA and Bodnar, SH and Lee, H and Kampf, JW and Incarvito, CD and Rheingold, AL}, year={2002}, month={Aug}, pages={10054–10061} }
 @article{shultz_2002, title={Structure-property relationships in new serniquinone-type ligands: Past, present, and future research efforts}, volume={23}, ISSN={["1548-9574"]}, DOI={10.1080/02603590214375}, abstractNote={The utility of cross-conjugated, redox-active semiquinone ligands and their complexes for exploration and elucidation of various molecular structure-property relationships is discussed.}, number={1}, journal={COMMENTS ON INORGANIC CHEMISTRY}, author={Shultz, DA}, year={2002}, pages={1–21} }
 @inbook{shultz_2002, place={New York}, title={Valence Tautomerism in Dioxolene Complexes of Cobalt}, ISBN={9783527600595 9783527303014}, url={http://dx.doi.org/10.1002/3527600590.ch8}, DOI={10.1002/3527600590.ch8}, abstractNote={This chapter contains sections titled: Introduction – Bistability, Hysteresis and Electronically Labile Materials Bistability and Hysteresis Electronically Labile Materials Valence Tautomerism in Dioxolene Complexes of Cobalt Valence Tautomerism – A General Chemical Description Valence Tautomerism – A Simplified MO Description VT Thermodynamics Experimental Determination of Thermodynamic Parameters Dependence of KVT Equilibrium on Ancillary Ligands Pressure-induced VT Light-induced VT and Rates of VT VT Complexes of Other Quinone Ligands and Redox Chemistry of VT Complexes Polymeric VT Materials Future Directions}, booktitle={Magnetism: Molecules to Materials II: Models and Experiments}, publisher={Wiley-VCH Verlag GmbH & Co. KGaA}, author={Shultz, David A.}, editor={Miller, Joel S. and Drillon, MarcEditors}, year={2002}, pages={281–306} }
 @article{bodnar_caneschi_dei_shultz_sorace_2001, title={A bis-bidentate dioxoleneligand induces thermal hysteresis in valence tautomerism interconversion processes}, DOI={10.1039/B106192P}, abstractNote={The use of a bis-bidentate ligand in a solid cobalt dioxolene complex affords the necessary cooperative properties that lead to thermal hysteresis in a valence tautomeric interconversion equilibrium.}, number={20}, journal={Chemical Communication}, author={Bodnar, S.H. and Caneschi, A. and Dei, A. and Shultz, D.A. and Sorace, L}, year={2001}, pages={2150–2151} }
 @article{bencini_daul_dei_mariotti_lee_shultz_sorace_2001, title={Charge distribution in bis-dioxolene radical metal complexes. Synthesis and DFT characterization of dinuclear Co(III) and Cr(III) complexes with a mixed-valent, S=1/2 semiquinone-catecholate ligand}, volume={40}, ISSN={["0020-1669"]}, DOI={10.1021/ic0007052}, abstractNote={Bis-dioxolene bridged dinuclear metal complexes of general formula M2(CTH)2(diox-diox)(PF6)n (n = 2, 3; M = Co(III), Cr(III); CTH = tetraazamacrocycle) have been synthesized using the bis-bidentate ligand 5,5'-di-tert-butyl-3,3',4,4'-tetrahydroxybiphenyl. These complexes were characterized by means of ESR, UV-vis, temperature dependent magnetic susceptibility, and cyclic voltammetry. Our results unambiguously suggest that the tripositive dimetal cations can be described as containing a fully delocalized bis-dioxolene trinegative radical ligand (Cat-Sq) bridging two tripositive metal cations. In this frame the sextet electronic ground state characterizes the Cr2(CTH)2(Cat-SQ)3+ as a result of the antiferromagnetic coupling of the radical bridging ligand with the two equivalent paramagnetic metal centers. The electronic and geometrical structure and the magnetic properties of Cat-Sq and of its complexes have been studied with density functional theory.}, number={7}, journal={INORGANIC CHEMISTRY}, author={Bencini, A and Daul, CA and Dei, A and Mariotti, F and Lee, H and Shultz, DA and Sorace, L}, year={2001}, month={Mar}, pages={1582–1590} }
 @article{caneschi_dei_lee_shultz_sorace_2001, title={Ferromagnetically coupled bis(semiquinone) ligand enforces high-spin ground states in bis-metal complexes}, volume={40}, ISSN={["0020-1669"]}, DOI={10.1021/ic000440r}, abstractNote={The π-connectivity of a bis(semiquinone) ligand enforces ferromagnetic coupling between the two semiquinone halves of the molecule. Using the ligand in connection with paramagnetic metal ions leads to complexes with S = 3 (M = NiII), S = 2 (M = CuII), and S = 2 (M = CrIII) ground states.}, number={2}, journal={INORGANIC CHEMISTRY}, author={Caneschi, A and Dei, A and Lee, H and Shultz, DA and Sorace, L}, year={2001}, month={Jan}, pages={408-+} }
 @article{shultz_bodnar_kampf_2001, title={Molecular structure of and exchange coupling in a bis(semiquinone) complex}, ISSN={["1359-7345"]}, DOI={10.1039/b008037n}, abstractNote={The first example of a structurally characterized, rationally 
designed, triplet ground-state bis(semiquinone) complex is presented; the 
intramolecular exchange coupling is ferromagnetic with J = +209 
cm−1.}, number={01}, journal={CHEMICAL COMMUNICATIONS}, author={Shultz, DA and Bodnar, SH and Kampf, JW}, year={2001}, pages={93–94} }
 @article{shultz_bodnar_kumar_lee_kampf_2001, title={Molecular structures of carbonyl-linked bis(dioxolene) complexes: Can a carbonyl group act as an effective ferromagnetic coupler?}, volume={40}, ISSN={["0020-1669"]}, DOI={10.1021/ic000956a}, abstractNote={Molecular structures of two bis(ZnIIdioxolene) complexes are described: (TpCum,MeZn)(2)1-H2 (C106H123.50B2N12O10Zn2), tetragonal, P4/ncc, a = 25.1810(2) A, b = 25.1810(2) A, c = 34.7744(2) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 8; (TpCum,MeZn)(2)1-H (C101H120B2N12O6Zn2), triclinic, P1, a = 13.6624(2) A, b = 13.80920(10) A, c = 26.62340(10) A, alpha = 96.6910(10) degrees, beta = 91.8560(10) degrees, gamma = 109.0190(10) degrees, Z = 2. One of the complexes, (TpCum,MeZn)(2)1-H2, has two protonated catecholate ligands, while the other complex, (TpCum,MeZn)(2)1-H, has one protonated catecholate and one semiquinone ligand. When reacted with PbO2, a labile S = 1, bis(ZnIIsemiquinone) complex is formed in which the two semiquinones are attached to a common carbonyl group.}, number={3}, journal={INORGANIC CHEMISTRY}, author={Shultz, DA and Bodnar, SH and Kumar, RK and Lee, H and Kampf, JW}, year={2001}, month={Jan}, pages={546–549} }
 @article{shultz_fico_boyle_kampf_2001, title={Observation of a hysteretic phase transition in a crystalline dinitroxide biradical that leads to magnetic bistability}, volume={123}, ISSN={["0002-7863"]}, DOI={10.1021/ja011341v}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTObservation of a Hysteretic Phase Transition in a Crystalline Dinitroxide Biradical That Leads to Magnetic BistabilityDavid A. Shultz, Rosario M. Fico,, Paul D. Boyle, and Jeff W. KampfView Author Information Department of Chemistry North Carolina State University Raleigh, North Carolina 27695-8204 Department of Chemistry University of Michigan Ann Arbor, Michigan 48109-1055 Cite this: J. Am. Chem. Soc. 2001, 123, 42, 10403–10404Publication Date (Web):September 27, 2001Publication History Received1 June 2001Published online27 September 2001Published inissue 1 October 2001https://doi.org/10.1021/ja011341vCopyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views378Altmetric-Citations28LEARN 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 (51 KB) Get e-AlertscloseSupporting Info (2)»Supporting Information Supporting Information SUBJECTS:Bistability,Exchange coupling,Hysteresis,Molecules,Phenyls Get e-Alerts}, number={42}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Shultz, DA and Fico, RM and Boyle, PD and Kampf, JW}, year={2001}, month={Oct}, pages={10403–10404} }
 @article{shultz_kumar_2001, title={One-electron reduction of an antiferromagnetically coupled triradical yields a mixed-valent biradical with enhanced ferromagnetic coupling}, volume={123}, ISSN={["0002-7863"]}, DOI={10.1021/ja010630g}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOne-Electron Reduction of an Antiferromagnetically Coupled Triradical Yields a Mixed-Valent Biradical with Enhanced Ferromagnetic CouplingDavid A. Shultz and R. Krishna KumarView Author Information Department of Chemistry North Carolina State University Raleigh, North Carolina 27695-8204 Cite this: J. Am. Chem. Soc. 2001, 123, 26, 6431–6432Publication Date (Web):June 8, 2001Publication History Received9 March 2001Published online8 June 2001Published inissue 1 July 2001https://doi.org/10.1021/ja010630gCopyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views570Altmetric-Citations21LEARN 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 (44 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Delocalization,Electron paramagnetic resonance spectroscopy,Molecular design,Molecules,Quantum mechanics Get e-Alerts}, number={26}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Shultz, DA and Kumar, RK}, year={2001}, month={Jul}, pages={6431–6432} }
 @article{depperman_bodnar_vostrikova_shultz_kirk_2001, title={Spin robustness of a new hybrid inorganic-organic high-spin molecule}, volume={123}, DOI={10.1021/ja003739h}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSpin Robustness of a New Hybrid Inorganic−Organic High-Spin MoleculeEzra C. Depperman, Scot H. Bodnar, Kira E. Vostrikova, David A. Shultz, and Martin L. KirkView Author Information Department of Chemistry, The University of New Mexico Albuquerque, New Mexico 87131-1096 Department of Chemistry, North Carolina State University Raleigh, North Carolina 27695-8204 October 23, 2000Cite this: J. Am. Chem. Soc. 2001, 123, 13, 3133–3134Publication Date (Web):March 7, 2001Publication History Revised2 January 2001Published online7 March 2001Published inissue 1 April 2001https://doi.org/10.1021/ja003739hCopyright © 2001 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views214Altmetric-Citations21LEARN 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 (33 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Electronic structure,Magnetic materials,Magnetic properties,Quantum mechanics,Spectroscopy Get e-Alerts}, number={13}, journal={Journal of the American Chemical Society}, author={Depperman, E. C. and Bodnar, S. H. and Vostrikova, K. E. and Shultz, David and Kirk, M. L.}, year={2001}, pages={3133–3134} }
 @article{shultz_2001, title={Structure-property relationships in building blocks for open-shell molecules and materials}, volume={122}, ISSN={["0379-6779"]}, DOI={10.1016/S0379-6779(01)00323-X}, abstractNote={The utility of cross-conjugated, redox-active molecules for exploration and elucidation of molecular structure–property relationships is demonstrated. In particular, connections between mixed valency and exchange coupling in two different oxidation states of cross-conjugated molecules are made.}, number={3}, journal={SYNTHETIC METALS}, author={Shultz, DA}, year={2001}, month={Aug}, pages={495–500} }
 @article{shultz_2001, title={Structure-property relationships in cross-conjugated, high-spin, dinuclear ligands: building blocks for open-shell molecules and materials}, volume={20}, ISSN={["0277-5387"]}, DOI={10.1016/S0277-5387(01)00664-7}, abstractNote={We assert that redox-active paramagnetic ligands will play an important role in molecule-based magnetic materials. In addition, cross-conjugated redox-active molecules are uniquely suited for correlating exchange coupling in biradical oxidation states with spin/charge delocalization in mixed-valent oxidation states. We present several examples of such ligands and emphasize pertinent molecular structure–property relationships.}, number={11-14}, journal={POLYHEDRON}, author={Shultz, DA}, year={2001}, month={May}, pages={1627–1631} }
 @inproceedings{bodnar_shultz_2000, title={Electronic and structural properties of unique semiquinone-like zinc complexes}, author={Bodnar, S and Shultz, D.}, year={2000} }
 @inproceedings{schultz_2000, title={New Organic Building Blocks for Open-Shell Molecules and Materials}, author={Schultz, D}, year={2000} }
 @inproceedings{shultz_2000, title={New Organic Building Blocks for Open-Shell Molecules and Materials}, author={Shultz, D}, year={2000} }
 @inproceedings{ramanathan_shultz_2000, title={Porphyrins as a building block for the assembly of organic molecular magnets}, author={Ramanathan, KK and Shultz, D.}, year={2000} }
 @article{shultz_hollomon_2000, title={Preparation and EPR spectroscopic investigation of conjugated oligomers containing semiquinone repeat units}, volume={12}, ISSN={["1520-5002"]}, DOI={10.1021/cm9907155}, abstractNote={Three protected catechol-containing conjugated oligomers have been prepared using Pd-mediated coupling reactions. Two of the oligomers are poly[o-phenylenevinylene] type while the other is poly[o-p...}, number={2}, journal={CHEMISTRY OF MATERIALS}, author={Shultz, DA and Hollomon, MG}, year={2000}, month={Feb}, pages={580–585} }
 @inproceedings{fico_shultz_2000, title={Relationship between phenyl torsion and exchange coupling in diaryl-trimethylenemethane-type dinitroxide biradicals}, author={Fico, R, Jr and Shultz, D.}, year={2000} }
 @inproceedings{mussari_shultz_2000, title={Spin-spin coupling in semiquinone-substituted porphyrins}, author={Mussari, C and Shultz, D.}, year={2000} }
 @inproceedings{beikmohamadi_shultz_2000, title={Substituent effects on spin distribution in 3-tert-butyl-5-aryl-semiquinones}, author={Beikmohamadi, M and Shultz, D.}, year={2000} }
 @inproceedings{shultz_2000, title={Synthesis and Properties of Novel Semiquinone Ligands}, author={Shultz, David}, year={2000} }
 @inproceedings{schultz_2000, title={Synthesis and Properties of Novel Semiquinone Ligands}, author={Schultz, D}, year={2000} }
 @article{shultz_bodnar_vostrikova_kampf_2000, title={Synthesis and structure of a complex having a quartet ground state with three entirely different spin carriers: Nitronyl nitroxide, o-semiquinone, and Cu-II}, volume={39}, ISSN={["0020-1669"]}, DOI={10.1021/ic0009122}, abstractNote={A "spin diverse" S = 3/2 ground-state complex, NN-SQCuTpCum,Me, has been prepared. The three S = 1/2 spin carriers are nitronyl nitroxide (NN), o-semiquinone (o-SQ), and cupric ion. The solid-state structure of the ZnII derivative, NN-SQZnTpCum,Me (C56H69BN8O4Zn), was determined: monoclinic, P2(1)/c, a = 12.5781(12) A, b = 17.7408(17) A, c = 24.440(2) A, alpha = 90.00 degrees, beta = 98.240(2) degrees, gamma = 90.00 degrees, Z = 4. The results of X-ray structural characterization of the ZnII derivative suggest substantial interaction between the two spin carriers NN and o-SQ. Indeed, strong intramolecular exchange coupling has been determined by variable-temperature magnetic susceptibility studies. Intraligand ferromagnetic exchange is considerably greater than kT, such that only the triplet state is populated at 300 K, and CuII-ligand exchange is ferromagnetic, with J = +75 cm-1.}, number={26}, journal={INORGANIC CHEMISTRY}, author={Shultz, DA and Bodnar, SH and Vostrikova, KE and Kampf, JW}, year={2000}, month={Dec}, pages={6091–6093} }
 @article{wu_sa o'neill_brousseau_mcconnell_shultz_linderman_feldheim_2000, title={Synthesis of nanometer-sized hollow polymer capsules from alkanethiol-coated gold particles}, ISSN={["1359-7345"]}, DOI={10.1039/b001019g}, abstractNote={A tripodal alkythiolate ligand has been assembled on gold 
nanoparticles, which upon metathesis polymerization and particle etching, 
yields crosslinked spherical hollow polymer capsules.}, number={9}, journal={CHEMICAL COMMUNICATIONS}, author={Wu, ML and SA O'Neill and Brousseau, LC and McConnell, WP and Shultz, DA and Linderman, RJ and Feldheim, DL}, year={2000}, pages={775–776} }
 @article{shultz_bodnar_kumar_kampf_1999, title={Both an oxidation/reduction sequence and deprotonation of a unique paramagnetic ligand lead to a mixed-valent complex}, volume={121}, ISSN={["0002-7863"]}, DOI={10.1021/ja9931675}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTBoth an Oxidation/Reduction Sequence and Deprotonation of a Unique Paramagnetic Ligand Lead to a Mixed-Valent ComplexDavid A. Shultz, Scot H. Bodnar, R. Krishna Kumar, and Jeff W. KampfView Author Information Department of Chemistry North Carolina State University Raleigh, North Carolina 27695-8204 Department of Chemistry, University of Michigan Ann Arbor, Michigan 48109-1055 Cite this: J. Am. Chem. Soc. 1999, 121, 45, 10664–10665Publication Date (Web):November 3, 1999Publication History Received2 September 1999Published online3 November 1999Published inissue 1 November 1999https://doi.org/10.1021/ja9931675Copyright © 1999 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views208Altmetric-Citations27LEARN 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 (94 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Anions,Deprotonation,Ligands,Potassium,Redox reactions Get e-Alerts}, number={45}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Shultz, DA and Bodnar, SH and Kumar, RK and Kampf, JW}, year={1999}, month={Nov}, pages={10664–10665} }
 @inbook{shultz_1999, title={Conformational exchange modulation in trimethylenemethane-type biradicals}, booktitle={Magnetic properties of organic materials}, publisher={New York: Marcel Dekker}, author={Shultz, D. A.}, year={1999}, pages={103–126} }
 @misc{shultz_lee_kumar_gwaltney_1999, title={Cross-conjugated bis(porphryin)s: Synthesis, electrochemical behavior, mixed valency, and biradical dication formation}, volume={64}, ISSN={["0022-3263"]}, DOI={10.1021/jo991046h}, abstractNote={The synthesis and characterization of seven (ZnII)2bis(porphyrin) molecules are described. The molecular structures of two bis(porphyrin)s (6 and 7) were determined by X-ray diffraction methods. Four of the compounds have their porphyrin moieties attached in a meta-fashion to a substituted benzene ring (1−4), two have porphyrin rings attached in a gem-fashion to a carbon−carbon double bond (6 and 7), and one bis(porphyrin) (5) has a p-phenylene coupler. Bis(porphyrin)s 1, 4, and 5 contain tetraaryl-type porphyrins, while 2, 3, 6, and 7 contain triarylethynylporphyrins. Except for exciton coupling in the unoxidized species, interaction between porphyrins is greater in the triarylethynyl-type bis(porphyrin)s than in the tetraaryl-type bis(porphyrin)s regardless of the number of bonds through which the interaction propagates. The cyclic voltammetry of the bis(porphyrin)s was examined, and a varying degree of interaction between electrophores within the series was found. Redox splitting was observed for porph...}, number={25}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Shultz, DA and Lee, H and Kumar, RK and Gwaltney, KP}, year={1999}, month={Dec}, pages={9124–9136} }
 @article{shultz_lee_gwaltney_sandberg_1999, title={Electronic properties of bisporphyrin biradical dications}, volume={334}, ISSN={["1058-725X"]}, DOI={10.1080/10587259908023342}, abstractNote={Abstract We describe the oxidations of bisporphyrins 1-Zn2 - 6-Zn2 , and present EPR spectra of chemically oxidized species that are consistent with exchange-coupled biradicals.}, number={1999}, journal={MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS}, author={Shultz, DA and Lee, H and Gwaltney, KP and Sandberg, KA}, year={1999}, pages={459–467} }
 @article{marinakos_shultz_feldheim_1999, title={Gold Nanoparticles as Templates for the Synthesis of Hollow Nanometer‐Sized Conductive Polymer Capsules}, volume={11}, ISSN={["0935-9648"]}, DOI={10.1002/(SICI)1521-4095(199901)11:1<34::AID-ADMA34>3.0.CO;2-I}, abstractNote={By Stella M. Marinakos, DavidA. Shultz,* andDaniel L. Feldheim*The organization of materials on the nanoscale is an im-portant objective of chemists and materials scientists. Con-trol over the spatial arrangement of nanoscopic buildingblocks often leads to new materials with chemical, mechan-ical, optical, or electronic properties distinctly differentfrom those of their component parts.}, number={1}, journal={Advanced Matter}, author={Marinakos, S.M. and Shultz, D.A. and Feldheim, D.L.}, year={1999}, month={Jan}, pages={34–37} }
 @article{shultz_bodnar_1999, title={Paramagnetic zinc(II) complexes of a bis(catechol): Dependence of product spin state on tantomerization of the bis(catechol) ligand}, volume={38}, ISSN={["1520-510X"]}, DOI={10.1021/ic981092k}, abstractNote={We report the preparation and characterization of zinc(II) hydrotris(3-cumenyl-5-methylpyrazolyl)borate (LZn) complexes, (LZn)(2)()1'-H and (LZn)(2)()1, of a bis(catechol) ligand. The formation of (LZn)(2)()1'-H, an S = (1)/(2) complex, rather than (LZn)(2)()1, an S = 1 complex, is observed due to tautomerization of a reaction intermediate. The biradical complex, (LZn)(2)()1, can be prepared from (LZn)(2)()1'-H by oxidation, a conversion that is accompanied by a blue-green to red-purple color change and an increase in spin from (1)/(2) to 1. The frozen solution EPR spectrum of the biradical complex (LZn)(2)()1 exhibits zero-field splitting and a Deltam(s)() = 2 transition characteristic of a triplet state. The temperature dependence of the EPR signal intensity is consistent with high-spin coupling of the unpaired electrons of the ligand.}, number={3}, journal={INORGANIC CHEMISTRY}, author={Shultz, DA and Bodnar, SH}, year={1999}, month={Feb}, pages={591–594} }
 @article{shultz_sandberg_1999, title={Semiempirical computational assessment of porphyrins as building blocks for molecule-based magnets: spin-spin coupling in radical-substituted metalloporphyrins}, volume={12}, ISSN={["0894-3230"]}, DOI={10.1002/(SICI)1099-1395(199901)12:1<10::AID-POC85>3.3.CO;2-7}, abstractNote={Semiempirical PM3-RHF-CI calculations were used to probe structure–exchange coupling relationships in radical-substituted Zn(II) porphyrins. The results support a number of important design elements for creating high-spin molecules from metalloporphyrins and the corresponding pi-cation radicals. The calculations showed that inactive porphyrin–active phenoxy union mode provides stronger exchange coupling than active porphyrin–inactive phenoxy union mode. Connecting radicals to the metalloporphyrin core via an ethynyl linkage eliminates severe torsion, permitting a coplanar alignment of the two pi systems. Metalloporphyrins could be excellent redox-activated exchange couplers: porphyrin radical cation exchange couples attached radicals more effectively than the neutral porphyrin. Finally, the magnitude of exchange coupling between a metalloporphyrin pi-cation radical depends on the nature of the attached radical. The results of the calculations were explained using a coupler spin analysis. Copyright © 1999 John Wiley & Sons, Ltd.}, number={1}, journal={JOURNAL OF PHYSICAL ORGANIC CHEMISTRY}, author={Shultz, DA and Sandberg, KA}, year={1999}, month={Jan}, pages={10–18} }
 @article{shultz_boal_lee_farmer_1999, title={Structure-property relationships in trimethylenemethane-type biradicals. 2. Synthesis and EPR spectral characterization of dinitroxide biradicals}, volume={64}, ISSN={["0022-3263"]}, DOI={10.1021/jo990061j}, abstractNote={Several trimethylenemethane-type (TMM-type) dinitroxide biradicals have been prepared that differ in tert-butylaminoxylphenyl ring torsion angles by virtue of different steric demands of their “spin-protecting groups”. In addition, the synthesis of a TMM-type dinitroxide having a planar π-system is reported. The synthetic route employed for the planar TMM-type biradical is general and should therefore expand the utility of TMM-type biradicals that are susceptible to bond torsions that attenuate exchange coupling. The compounds presented are designed to be effective to map out J-coupling/conformation space in TMM-type biradicals. EPR spectroscopic parameters (hfcc and D-values) were compared to determine if their values reflected differences in conformation in the series of biradicals. Interestingly, neither N- nor H-hfcc varied within our series of biradicals/monoradicals in a regular fashion, indicating that there is no apparent relationship between N- or H-hfcc and conformation (as judged by molecular m...}, number={12}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Shultz, DA and Boal, AK and Lee, H and Farmer, GT}, year={1999}, month={Jun}, pages={4386–4396} }
 @article{shultz_lee_fico_1999, title={Synthesis and characterization of a planarized, trimethylenemethane-type bis(semiquinone) biradical}, volume={55}, ISSN={["0040-4020"]}, DOI={10.1016/s0040-4020(99)00714-0}, abstractNote={The synthesis and characterization of a biradical in which two semiquinone rings are held rigidly co-planar and are attached in a geminal fashion to a carbon-carbon double bond is described. The results of cyclic voltammetry and variable-temperature EPR studies are interpreted in terms of the interaction of the two semiquinones through the carbon-carbon double bond coupling unit.}, number={41}, journal={TETRAHEDRON}, author={Shultz, DA and Lee, HY and Fico, RM}, year={1999}, month={Oct}, pages={12079–12086} }
 @article{shultz_gwaltney_lee_1998, title={A Modified Procedure for Sonogashira Couplings:  Synthesis and Characterization of a Bisporphyrin, 1,1-Bis[zinc(II) 5‘-ethynyl-10‘,15‘,20‘-trimesitylporphyrinyl]methylenecyclohexane}, volume={63}, ISSN={0022-3263 1520-6904}, url={http://dx.doi.org/10.1021/jo980098o}, DOI={10.1021/jo980098o}, abstractNote={The preparation of a bisporphyrin, 1,1-bis[zinc(II) 5‘-ethynyl-10‘,15‘,20‘-trimesitylporphyrinyl]methylenecyclohexane (1), is described. The new molecule was prepared by two routes employing modified palladium-mediated coupling methodology. Our modification consists of in situ liberation of alkyne from the corresponding TMS-protected compound. This variation decreases yields of undesired products presumably by keeping the unprotected alkyne concentration low during the reaction. In addition, our method obviates TMS-alkyne deprotection and subsequent purification steps. The electronic absorption spectrum of 1 is compared to two model compounds.}, number={12}, journal={The Journal of Organic Chemistry}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Gwaltney, Kevin P. and Lee, Hyoyoung}, year={1998}, month={Jun}, pages={4034–4038} }
 @inproceedings{boal_farmer_shultz_1998, title={EPR Spectral Characterization of Bis(Semiquinones}, author={Boal, A and Farmer, G and Shultz, D}, year={1998} }
 @article{shultz_boal_campbell_1998, title={Effect of aliphatic amine bases on the aggregation of alkali metal salts of 3,5-di-tert-butylsemiquinone (3,5-DBSQ)}, volume={37}, ISSN={["0020-1669"]}, DOI={10.1021/ic971113v}, abstractNote={The alkali metal salts (Li+, Na+, K+) of 3,5-di-tert-butylsemiquinone anion (3,5-DBSQ) have been prepared in the presence of three amine bases, triethylamine (TEA), tetramethylethylenediamine (TMEDA), and pentamethyldiethyltriamine (PMDTA), as well as in the absence of amine in two solvents, toluene and THF. EPR spectral evidence shows that for M(3,5-DBSQ), aggregation of the lithium and sodium salts is effectively prohibited by Lewis basic amines PMDTA and TMEDA, with the former being more effective than the latter. The EPR spectra of the least Lewis acidic metal ion, K+, are unaffected by addition of amines. In the absence of amines, the coordinating solvent, THF, is effective at preventing aggregation, while substantial aggregation occurs in the noncoordinating solvent, toluene. The effectiveness of PMDTA is so great that M(3,5-DBSQ) (M = Li+ and Na+) aggregation is prevented even in toluene. The combination of solution and frozen solution spectra is best for determining the presence of aggregates due ...}, number={7}, journal={INORGANIC CHEMISTRY}, author={Shultz, DA and Boal, AK and Campbell, NP}, year={1998}, month={Apr}, pages={1540–1543} }
 @article{sagara_midorikawa_shultz_zhao_1998, title={Electrochemical and Spectroelectrochemical Study of a Bis(arylgalvinol)-Substituted Alkyl Disulfide Monolayer and Mixed Monolayers on Polycrystalline Gold}, volume={14}, ISSN={0743-7463 1520-5827}, url={http://dx.doi.org/10.1021/la980136z}, DOI={10.1021/la980136z}, abstractNote={The monolayer of bis(arylgalvinol)-substituted alkyl disulfide and mixed monolayers with decanethiol (DT) on a polycrystalline gold electrode were characterized in an aqueous solution by means of cyclic voltammetry and in situ electroreflectance (ER) spectroscopy. Both neat and mixed monolayers exhibited a quasi-reversible redox response of galvinol/galvinoxyl radical couple (GalH/Gal•) at the same formal potentials. The ER signal involved responses due to both the redox reaction and the Stark effect on Gal•. The ER spectrum of the redox reaction showed a difference absorption spectral feature, and it was found that the absorption bands of both immobilized GalH and Gal• are red shifted in comparison to their absorption bands measured in organic solvents. The ER spectral profile for the redox reaction was unaffected by mixing with DT, while the contribution of Stark effect on Gal• to the ER signal was significantly suppressed by increasing the amount of DT in the monolayer. The amount of immobilized GalH i...}, number={13}, journal={Langmuir}, publisher={American Chemical Society (ACS)}, author={Sagara, Takamasa and Midorikawa, Takahiro and Shultz, David A. and Zhao, Qi}, year={1998}, month={Jun}, pages={3682–3690} }
 @inproceedings{shultz_lee_gwaltney_1998, title={Electronic Properties of Bisporphyrin Biradical Dications}, author={Shultz, D and Lee, H and Gwaltney, K}, year={1998} }
 @article{sandberg_shultz_1998, title={Improved method for estimating the ZFS parameter D for delocalized biradicals}, volume={11}, ISSN={["0894-3230"]}, DOI={10.1002/(SICI)1099-1395(1998110)11:11<819::AID-POC72>3.0.CO;2-W}, abstractNote={An ‘average’ approximation for calculating the zero-field splitting parameter, D, gives reasonable results when used to calculate D values for non-disjoint delocalized organic biradicals. When used to calculate disjoint localized organic biradicals the D values are approximately half the experimental values. © 1998 John Wiley & Sons, Ltd.}, number={11}, journal={JOURNAL OF PHYSICAL ORGANIC CHEMISTRY}, author={Sandberg, KA and Shultz, DA}, year={1998}, month={Nov}, pages={819–824} }
 @inproceedings{schultz_gwaltney_lee_1998, title={Oxidation of a Bis[Zn(II) Porphyrin] Yields a Nondisjoint Dication-Biradical Exhibiting a ∆Ms=2 Transition}, author={Schultz, D and Gwaltney, K and Lee, H}, year={1998} }
 @misc{shultz_lee_gwaltney_1998, title={Oxidation of a bis[Zn(II) porphyrin] yields a nondisjoint, exchange-coupled pi dication-biradical}, volume={63}, ISSN={["0022-3263"]}, DOI={10.1021/jo981488d}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOxidation of a Bis[Zn(II) porphyrin] Yields a Nondisjoint, Exchange-Coupled π Dication-BiradicalDavid A. Shultz, Hyoyoung Lee, and Kevin P. GwaltneyView Author Information Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204 Cite this: J. Org. Chem. 1998, 63, 22, 7584–7585Publication Date (Web):October 3, 1998Publication History Received29 July 1998Published online3 October 1998Published inissue 1 October 1998https://doi.org/10.1021/jo981488dCopyright © 1998 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views295Altmetric-Citations16LEARN 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 (99 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Electron paramagnetic resonance spectroscopy,Exchange coupling,Molecules,Oxidation,Pyrroles Get e-Alerts}, number={22}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Shultz, DA and Lee, HY and Gwaltney, KP}, year={1998}, month={Oct}, pages={7584–7585} }
 @inproceedings{schultz_borbeau_boal_1998, place={Dallas}, title={Structure-Property Relationships in Trimethylenemethane-type Biradicals: Bis-(3,5-Di-tert-butyl-4-phenoxyl)methylene-adamantane vs. Bis-(3,5-Di-tert-butyl-4-phenoxyl)methylene-norbornane}, author={Schultz, D and Borbeau, M and Boal, A}, year={1998} }
 @inproceedings{boal_farmer_shultz_1998, title={Structure-Property Relationships in Trimethylenemethane-type Bis(nitroxide) Biradicals}, author={Boal, A and Farmer, G and Shultz, D}, year={1998} }
 @article{schultz_gwaltney_lee_1998, title={Synthesis and Characterization of Phenylnitroxide-Substituted Zinc(II) Porphyrins}, volume={63}, ISSN={["0022-3263"]}, DOI={10.1021/jo971736q}, abstractNote={The syntheses and fluid-solution EPR spectra of nitroxide-substituted porphyrins 1-3 are described. The phenylnitroxide is attached to the meso-position of three porphyrins: (a) directly through a single bond (1); (b) through an ethenyl group (2); and (c) through an ethynyl group (3). The spin distribution in each of the three radicals is discussed and compared to model compounds 4-9. It is suggested that delocalization increases in the order 2, 1, 3.}, number={3}, journal={Journal of Organic Chemistry}, author={Schultz, D and Gwaltney, K.P. and Lee, H.J.}, year={1998}, pages={769–774} }
 @article{shultz_farmer_1998, title={Synthesis and characterization of a nitroxide-semiquinone biradical}, volume={63}, ISSN={["0022-3263"]}, DOI={10.1021/jo980562p}, abstractNote={The synthesis and characterization of an anion biradical, 1(-)(*)(*), composed of semiquinone and nitroxide functionalities is described. The biradical was prepared by reduction of the nitroxide-orthoquinone precursor using both electrochemical and chemical methods. The zero-field-splitting parameter, |D/hc|, for 1(-)(*)(*) is consistent with the proposed electronic structure, based on a comparison to |D/hc| of related biradicals. Finally, the results of variable-temperature EPR spectroscopy are in agreement with ferromagnetic (high-spin) coupling of the two unpaired electrons through the m-phenylene group.}, number={18}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Shultz, DA and Farmer, GT}, year={1998}, month={Sep}, pages={6254–6257} }
 @article{shultz_boal_farmer_1998, title={Synthesis of bis(semiquinone)s and their electrochemical and electron paramagnetic resonance spectral characterization}, volume={63}, ISSN={["0022-3263"]}, DOI={10.1021/jo981597s}, abstractNote={The syntheses of three new bis(semiquinone)s (2••2-, 3••2-, and 5••2-) linked through carbon−carbon double bonds in a geminal fashion (2••2- and 3••2-), and through an sp3 carbon (5••2-), are presented, as well as the results of variable-temperature EPR (VT-EPR) spectroscopy on these biradicals and two previously reported bis(semiquinone)s, 1••2- and 4••2-. We suggest that the potential difference in redox couples associated with a biradical is useful for qualitatively assessing changes in the exchange parameter within an isostructural series. The zero-field-splitting parameters for 1••2-−5••2- are consistent with their electronic structures:  biradicals 1••2-−3••2- which have conjugating groups attached to the semiquinone rings have D-values less than 5••2-, a bis(semiquinone) that lacks such a conjugating group. Also, the D-value of 3••2- is significantly less than those of 1••2- and 2••2-, in agreement with larger interelectron separation in 3••2-, a biradical with quinone-methide π-system delocalizati...}, number={25}, journal={JOURNAL OF ORGANIC CHEMISTRY}, author={Shultz, DA and Boal, AK and Farmer, GT}, year={1998}, month={Dec}, pages={9462–9469} }
 @inproceedings{shultz_gwaltney_lee_1998, title={Topology-Mediated Spin-Spin Coupling in Bis(Porphyrin) Biradical Dications}, author={Shultz, D and Gwaltney, K and Lee, H}, year={1998} }
 @article{brousseau_zhao_shultz_feldheim_1998, title={pH-Gated Single-Electron Tunneling in Chemically Modified Gold Nanoclusters}, volume={120}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja981262s}, DOI={10.1021/ja981262s}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTpH-Gated Single-Electron Tunneling in Chemically Modified Gold NanoclustersLouis C. Brousseau, Qi Zhao, David A. Shultz, and Daniel L. FeldheimView Author Information Department of Chemistry, North Carolina State University Raleigh, North Carolina 27695 Cite this: J. Am. Chem. Soc. 1998, 120, 30, 7645–7646Publication Date (Web):July 21, 1998Publication History Received15 April 1998Published online21 July 1998Published inissue 1 August 1998https://doi.org/10.1021/ja981262sCopyright © 1998 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views361Altmetric-Citations75LEARN 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 (42 KB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Cluster chemistry,Electrical properties,Gold,Nanoclusters,Nanoparticles Get e-Alerts}, number={30}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Brousseau, Louis C. and Zhao, Qi and Shultz, David A. and Feldheim, Daniel L.}, year={1998}, month={Aug}, pages={7645–7646} }
 @article{anderson_shultz_dougherty_1997, title={Attempted Synthesis of a Stable, Quintet, Tetraphenoxyl Tetraradical:  Facile Rearrangement of a Substituted Bicyclobutane}, volume={62}, ISSN={0022-3263 1520-6904}, url={http://dx.doi.org/10.1021/jo970614v}, DOI={10.1021/jo970614v}, abstractNote={The preparation of tetraphenol 3 and its attempted oxidation to tetraradical 2 are described. Tetraphenoxyl 2 was envisioned as a more stable analog of the previously reported, quintet tetraradical 1. However, EPR studies on 3 and model compounds and crystallographic characterization of the product from oxidation of 3 suggest that 2 is not a viable target. Apparently, 2 or an intermediate in the multistep oxidation path leading to it undergoes a ring closure to a bicyclobutane. The bicyclobutane, in turn, undergoes a surprisingly facile rearrangement to the analogous butadiene structure.}, number={22}, journal={The Journal of Organic Chemistry}, publisher={American Chemical Society (ACS)}, author={Anderson, Kraig K. and Shultz, David A. and Dougherty, Dennis A.}, year={1997}, month={Oct}, pages={7575–7584} }
 @inproceedings{shultz_1997, title={Molecular Assemblies with Interesting/Useful Magnetic or Magnetooptic Properties}, author={Shultz, D.}, year={1997} }
 @inbook{schultz_1997, title={Organic Chemistry}, booktitle={Chemistry, A Molecular Science}, publisher={Patterson Jones Interactive}, author={Schultz, D}, editor={Wertz, D.W.Editor}, year={1997} }
 @misc{shultz_1997, title={Organic Polymers as Building Blocks for Molecule-Based Magnets}, author={Shultz, D}, year={1997}, month={Apr} }
 @article{shultz_boal_driscoll_farmer_kitchin_miller_tew_1997, title={Preparation of paramagnetic ligands for coordination complexes and networks with interesting magnetic properties}, volume={305}, DOI={10.1080/10587259708045067}, abstractNote={Abstract We hypothesize that paramagnetic, multidentate, chelating ligands can be used to create molecular magnetic materials with high ordering temperatures. The ligands proposed for such materials are di-, tri-, and oligosemiquinone molecules. This paper will discuss the synthesis and characterization of these semiquinone ligands.}, number={1997}, journal={Molecular Crystals and Liquid Crystals Science and Technology. Section A, Molecular Crystals and Liquid Crystals}, author={Shultz, David and Boal, A. K. and Driscoll, D. J. and Farmer, G. T. and Kitchin, J. R. and Miller, D. B. and Tew, G. N.}, year={1997}, pages={303} }
 @article{shultz_boal_farmer_1997, title={The biradical, bis(3,5-di-tert-butyl-4-phenoxyl)methyleneadamantane, exhibits matrix-dependent EPR spectra suggesting rotamer bistability with differential exchange coupling}, volume={119}, ISSN={["0002-7863"]}, DOI={10.1021/ja964330o}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTThe Biradical, Bis(3,5-di- tert-butyl-4-phenoxyl)methyleneadamantane, Exhibits Matrix-Dependent EPR Spectra Suggesting Rotamer Bistability with Differential Exchange CouplingDavid A. Shultz, Andrew K. Boal, and Gary T. FarmerView Author Information Department of Chemistry North Carolina State University Raleigh, North Carolina 27695-8204 Cite this: J. Am. Chem. Soc. 1997, 119, 16, 3846–3847Publication Date (Web):April 23, 1997Publication History Received17 December 1996Published online23 April 1997Published inissue 1 April 1997https://doi.org/10.1021/ja964330oCopyright © 1997 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views371Altmetric-Citations37LEARN 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 (150 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Aromatic compounds,Electron paramagnetic resonance spectroscopy,Exchange coupling,Hydrocarbons,Solvents Get e-Alerts}, number={16}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Shultz, DA and Boal, AK and Farmer, GT}, year={1997}, month={Apr}, pages={3846–3847} }
 @book{pavia_lampman_kriz_1996, place={Fort Worth, TX}, edition={2nd}, title={Introduction to Spectroscopy}, publisher={Harcourt Brace College Publishers}, author={Pavia, D.L. and Lampman, G.M. and Kriz, G.S.}, editor={Schultz, D.Editor}, year={1996} }
 @inproceedings{schultz_hollomon_1996, place={Orlando}, title={Preparation and Characterization of Conjugated Polymers with Semiquinone Repeat Units}, author={Schultz, D and Hollomon, M}, year={1996} }
 @inproceedings{schultz_gwaltney_1996, title={Preparation and Characterization of a Nitroxide-Substituted Metalloporphyrin}, author={Schultz, D.A. and Gwaltney, K.P.}, year={1996} }
 @article{shultz_zhao_1996, title={Preparation and characterization of a bis-galvinoxyl-disulfide}, volume={37}, ISSN={0040-4039}, url={http://dx.doi.org/10.1016/s0040-4039(96)02067-9}, DOI={10.1016/s0040-4039(96)02067-9}, abstractNote={Abstract The synthesis of a biradical disulfide is described. This biradical exhibits an EPR spectrum consistent with ¦ J ¦>> a . Cyclic voltammetry of monolayers of this biradical shows that the radical monolayer exhibits less pH-dependence than its phenol counterpart.}, number={49}, journal={Tetrahedron Letters}, publisher={Elsevier BV}, author={Shultz, David A. and Zhao, Qi}, year={1996}, month={Dec}, pages={8837–8840} }
 @inproceedings{schultz_1996, title={Preparation of Paramagnetic Ligands for Coordination-Complexes and Networks With Interesting Magnetic Properties}, author={Schultz, D}, year={1996}, month={Jul} }
 @inproceedings{schultz_1996, title={Radical-Substituted Alkanethiol Monolayers: Toward Molecule-Based Multilayer Magnetic Materials}, author={Schultz, D}, year={1996}, month={Oct} }
 @inproceedings{shultz_1996, title={Semiquinones as Building Blocks for Molecular Magnets}, author={Shultz, D}, year={1996}, month={Jul} }
 @inproceedings{schultz_1995, title={Metal-Semiquinone Complexes as Building Blocks for Molecular Magnetic Materials}, author={Schultz, D}, year={1995} }
 @article{schultz_boal_1995, title={Nitroxyl-Galvinoxyl – A New Biradical}, volume={272}, DOI={10.1080/10587259508055274}, abstractNote={Abstract The synthesis and solution phase EPR spectrum of a new biradical is presented. The H-hyperfine coupling constants of the biradical indicate interaction of the unpaired electrons in the molecule.}, number={1}, journal={Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals}, author={Schultz, D and Boal, AK}, year={1995}, pages={75–79} }
 @article{shultz_boal_driscoll_kitchin_tew_1995, title={Preparation and Characterization of a Bis-Semiquinone: a Bidentate Dianion Biradical}, volume={60}, ISSN={0022-3263 1520-6904}, url={http://dx.doi.org/10.1021/jo00117a004}, DOI={10.1021/jo00117a004}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPreparation and Characterization of a Bis-Semiquinone: a Bidentate Dianion BiradicalDavid A. Shultz, Andrew K. Boal, Debra J. Driscoll, John R. Kitchin, and Gregory N. TewCite this: J. Org. Chem. 1995, 60, 12, 3578–3579Publication Date (Print):June 1, 1995Publication History Published online1 May 2002Published inissue 1 June 1995https://doi.org/10.1021/jo00117a004RIGHTS & PERMISSIONSArticle Views284Altmetric-Citations30LEARN 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 PDF (253 KB) Get e-AlertsSupporting Info (2)»Supporting Information Supporting Information Get e-Alerts}, number={12}, journal={The Journal of Organic Chemistry}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Boal, Andrew K. and Driscoll, Debra J. and Kitchin, John R. and Tew, Gregory N.}, year={1995}, month={Jun}, pages={3578–3579} }
 @inproceedings{schultz_1995, title={Synthesis and Characterization of Trisemiquinone Ligands}, booktitle={209th National ACS Meeting}, author={Schultz, D}, year={1995} }
 @inproceedings{schultz_sandberg_boal_1995, title={Synthesis of Radical-Substituted Metalloporphyrins}, author={Schultz, DA and Sandberg, KA and Boal, AK}, year={1995} }
 @inproceedings{linderman_tennyson_schultz_1994, title={Comparative Stability of Fluoroketone Hemi-thioacetals, -Ketals, and -Hydrates}, author={Linderman, R.J and Tennyson, S.D. and Schultz, D.A.}, year={1994} }
 @article{linderman_tennyson_shultz_1994, title={Comparative stability of fluoroketone hemi-thio acetals, ketals and hydrates}, volume={35}, ISSN={0040-4039}, url={http://dx.doi.org/10.1016/s0040-4039(00)78240-2}, DOI={10.1016/s0040-4039(00)78240-2}, abstractNote={The relative thermodynamic stability of hemi-thio acetals, ketals and hydrates of fluoroketones have been determined by AM1 and NMDO calculations of isodesmic reactions.}, number={35}, journal={Tetrahedron Letters}, publisher={Elsevier BV}, author={Linderman, Russell J. and Tennyson, Scott D. and Shultz, David A.}, year={1994}, month={Aug}, pages={6437–6440} }
 @article{shultz_tew_1994, title={Electrochemical Oxidation of a Galvinol-Substituted Alkanethiol Monolayer}, volume={59}, ISSN={0022-3263 1520-6904}, url={http://dx.doi.org/10.1021/jo00100a012}, DOI={10.1021/jo00100a012}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical Oxidation of a Galvinol-Substituted Alkanethiol MonolayerDavid A. Shultz and Gregory N. TewCite this: J. Org. Chem. 1994, 59, 21, 6159–6160Publication Date (Print):October 1, 1994Publication History Published online1 May 2002Published inissue 1 October 1994https://doi.org/10.1021/jo00100a012RIGHTS & PERMISSIONSArticle Views140Altmetric-Citations11LEARN 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 PDF (266 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts}, number={21}, journal={The Journal of Organic Chemistry}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Tew, Gregory N.}, year={1994}, month={Oct}, pages={6159–6160} }
 @book{fox_whitesell_1994, place={Sudbury, Mass.}, title={Organic Chemistry}, publisher={Jones and Bartlett}, author={Fox, M and Whitesell, J}, editor={Schultz, D.Editor}, year={1994} }
 @inproceedings{schultz_1994, title={Recent Advances in the Synthesis of High-spin Organic Molecules}, author={Schultz, D}, year={1994} }
 @inproceedings{shultz_1994, title={Recent Advances in the Synthesis of Multispin Organic Molecules}, author={Shultz, D}, year={1994} }
 @inproceedings{schultz_tew_1994, title={Synthesis and Characterization of Galvinol-Substituted Alkanethiols}, author={Schultz, D.A. and Tew, G.N}, year={1994}, month={Aug} }
 @inproceedings{schultz_driscoll_1994, title={Synthesis and Characterization of Galvinol-substituted SALEN Ligands}, author={Schultz, D and Driscoll, DJ}, year={1994}, month={Aug} }
 @inproceedings{shultz_driscoll_1994, title={Synthesis and Characterization of Galvinol-substituted Salen Ligands}, author={Shultz, D and Driscoll, D.J.}, year={1994} }
 @inproceedings{schultz_boal_1994, title={Synthesis and Characterization of New Galvinoxyl Radical Derivatives}, author={Schultz, D and Boal, A.K.}, year={1994} }
 @inproceedings{schultz_hollomon_1994, place={Washington}, title={Synthesis and Characterization of Organic Polymers with Paramagnetic Repeat Units}, author={Schultz, DA and Hollomon, MG}, year={1994}, month={Aug} }
 @inproceedings{schultz_sandberg_1994, title={Synthesis and Characterization of Paramagnetic Species Generated from a Metallotetraphenylporphyrin Derivative}, author={Schultz, DA and Sandberg, KA}, year={1994}, month={Aug} }
 @article{jacobs_shultz_jain_novak_dougherty_1993, title={Evaluation of potential ferromagnetic coupling units: the bis(TMM)  bis(trimethylenemethane)] approach to high-spin organic molecules}, volume={115}, DOI={10.1021/ja00058a020}, abstractNote={Four new hydrocarbon tetraradicals, 1-4, each composed of two triplet trimethylenemethane (TMM) subunits linked 
by a potential ferromagnetic coupling unit (FC), were synthesized and characterized by variable-temperature electron paramagnetic resonance (EPR) spectroscopy. Simulation of the EPR powder spectra and a priori calculation of the zero-field splitting parameters 
aided spectral assignment. The Heisenberg Hamiltonian appears to quantitatively model relative spin-state energies in 1-4. In three cases ferromagnetic coupling was achieved, as evidenced by quintet ground states in the resulting tetraradicals. In one case, strong evidence for antiferromagnetic coupling was obtained.}, number={5}, journal={Journal of the American Chemical Society}, author={Jacobs, S.J. and Shultz, D.A. and Jain, R. and Novak, J. and Dougherty, D.A.}, year={1993}, pages={1744–1753} }
 @inproceedings{schultz_1993, title={Macrocyclic Tetrapyrrole Assemblies as Building Blocks for Molecular Magnetic Materials}, author={Schultz, D}, year={1993} }
 @inproceedings{schultz_1993, title={Preparation of meso-Tetra(4-galvinolphenyl)porphyrin — A Building Block for Molecular Magnetic Materials}, author={Schultz, D}, year={1993} }
 @article{shultz_knox_morgan_sandberg_tew_1993, title={Preparation of meso-tetra(4-galvinolphenyl)porphyrin—A building block for molecular magnetic materials}, volume={34}, ISSN={0040-4039}, url={http://dx.doi.org/10.1016/s0040-4039(00)60593-2}, DOI={10.1016/s0040-4039(00)60593-2}, abstractNote={The synthesis and oxidative electrochemistry of a free-radical substituted metalloporphyrin are described. The porphyrin is prepared in four steps in good yield. Oxidation at a platinum electrode shows the molecule undergoes five reversible one-electron transfers to a stable pentaradical.}, number={25}, journal={Tetrahedron Letters}, publisher={Elsevier BV}, author={Shultz, David A. and Knox, David A. and Morgan, Larry W. and Sandberg, Kay and Tew, Gregory N.}, year={1993}, month={Jun}, pages={3975–3978} }
 @inbook{dougherty_grubbs_kaisaki_chang_jacobs_shultz_anderson_jain_ho_stewart_1991, title={Approaches to Magnetic Organic Materials}, ISBN={9789401054355 9789401132541}, url={http://dx.doi.org/10.1007/978-94-011-3254-1_6}, DOI={10.1007/978-94-011-3254-1_6}, booktitle={Magnetic Molecular Materials}, publisher={Springer Netherlands}, author={Dougherty, D. A. and Grubbs, R. H. and Kaisaki, D. A. and Chang, W. and Jacobs, S. J. and Shultz, D. A. and Anderson, K. K. and Jain, R. and Ho, P. T. and Stewart, E. G.}, year={1991}, pages={105–120} }
 @article{shultz_fox_1990, title={Structural effects on the disproportionation equilibrium of tethered tetraphenylethylene radical anions}, volume={55}, ISSN={0022-3263 1520-6904}, url={http://dx.doi.org/10.1021/jo00290a043}, DOI={10.1021/jo00290a043}, abstractNote={The electrochemistry of four bis[n.1]metacyclophanylidenes has been studied by cyclic and differential pulse voltammetric methods. The potential differences between the first and second reduction steps for these cyclophanes depend on the length of the hydrocarbon tethers and therefore on the magnitude of phenyl ring torsion}, number={3}, journal={The Journal of Organic Chemistry}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Fox, Marye Anne}, year={1990}, month={Feb}, pages={1047–1051} }
 @article{shultz_fox_1989, title={Effect of phenyl ring torsional rigidity on the photophysical behavior of tetraphenylethylenes}, volume={111}, ISSN={0002-7863}, url={http://dx.doi.org/10.1021/ja00198a049}, DOI={10.1021/ja00198a049}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTEffect of phenyl ring torsional rigidity on the photophysical behavior of tetraphenylethylenesDavid A. Shultz and Marye Anne FoxCite this: J. Am. Chem. Soc. 1989, 111, 16, 6311–6320Publication Date (Print):August 1, 1989Publication History Published online1 May 2002Published inissue 1 August 1989https://doi.org/10.1021/ja00198a049RIGHTS & PERMISSIONSArticle Views850Altmetric-Citations86LEARN 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 PDF (1 MB) Get e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts}, number={16}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Shultz, David A. and Fox, Marye Anne}, year={1989}, month={Aug}, pages={6311–6320} }
 @article{shultz_fox_1988, title={Spectroscopic Properties of [n.1]-metacyclophanylidenes}, volume={29}, DOI={10.1016/S0040-4039(00)80499-2}, abstractNote={The syntheses and fluorescence emission spectra of a series of bis-[n.1]-metacyclophanenylidenes (1: n=4; 2: n=5; 3: n=6) are discussed. The photophysical properties of 1–3 are compared to a model compound, tetrakis-(m-tolyl)-ethylene, 4. Varying the degree of phenyl ring torsional freedom drastically alters the fate of the arylethylene excited singlet. Compound 1 exhibits strong fluorescence at room temperature (∅f = 0.43), while 2 and 3, though over ten times less fluorescent (∅f(2) = 0.03, ∅f (3)= 0.01), are still at least ten times more fluorescent than 4 (∅f < 0.001). These results are suggestive of the importance of phenyl ring torsional motion in the nonradiative decay of the excited singlet state. The light-induced ring closure, typical of arylethylenes, is attenuated in 1–3.}, number={35}, journal={Tetrahedron Letters}, author={Shultz, D.A. and Fox, M.A.}, year={1988}, pages={4377–4379} }
 @article{fox_shultz_1988, title={Twisting in the tetraphenylethylene dianion}, volume={53}, ISSN={0022-3263 1520-6904}, url={http://dx.doi.org/10.1021/jo00253a036}, DOI={10.1021/jo00253a036}, abstractNote={The dipotassium salt of the tetraphenylethylene dianion (1/sup 2 -/) has been studied by /sup 1/H and /sup 13/C NMR spectroscopy and ..pi..-MO calculational techniques. Analysis of one-bond and three-bond carbon-carbon coupling constants permits a description of the geometry of the contact ion pair of 1/sup 2 -/. A linear relationship between ..pi.. bond order and carbon-carbon coupling constants, which provides information concerning the torsional angles about those bonds was noted. The preferred geometry of 1/sup 2 -/ is one in which the C/sub ..cap alpha../-C/sub /alpha'// torsional angle is closer to the C/sub ..cap alpha../-C/sub /alpha'// torsional angle of neutral 1 than to 90/degrees/, with the estimated range of this torsional angle being 8.4-28/degrees/. 41 references, 2 figures, 5 tables.}, number={18}, journal={The Journal of Organic Chemistry}, publisher={American Chemical Society (ACS)}, author={Fox, Marye Anne and Shultz, David}, year={1988}, month={Sep}, pages={4386–4390} }
 @inproceedings{shultz_boal, title={Synthesis and Characterization of New Galvinoxyl Radical Derivatives}, author={Shultz, D.A. and Boal, A.K.} }