@article{fayad_bui_shepard_castellano_2020, title={Photochemical Upconversion in Water Using Cu(I) MLCT Excited States: Role of Energy Shuttling at the Micellar/Water Interface}, volume={3}, ISSN={2574-0962 2574-0962}, url={http://dx.doi.org/10.1021/acsaem.0c02492}, DOI={10.1021/acsaem.0c02492}, abstractNote={Photochemical upconversion (UC) through triplettriplet annihilation (TTA), which employs a visible absorbing triplet photosensitizer and an annihilator, is a process that generates a high energy photon from two lower energy photons.TTA-UC has been largely developed in pure organic solvents and solid-state polymeric constructs while featuring near exclusive use of rare and expensive metals within the photosensitizer.In this current investigation, we demonstrate that TTA-UC from the long lifetime earthabundant photosensitizer [Cu(dsbtmp)2](PF)6 (dsbtmp = 2,9di(sec-butyl)-3,4,7,8-tetramethyl-1,10-phenanthroline), abbreviated as Cu-PS, functions in water through encapsulation within a cationic-based assembly.Cetyltrimethylammonium bromide (CTAB) was the surfactant of choice as it electrostatically binds the negatively charged water-soluble 10-phenylanthracene-9-carboxylate (PAC) acceptor/annihilator and ultimately facilitated energy transfer across the interface.Efficient and diffusion limited triplettriplet energy transfer (TTET) from Cu-PS to the PAC acceptor was achieved in this aqueous assembly.Unfortunately, the hindered mobility of the PAC moieties ultimately hampered the annihilation process and this was reflected in attenuated TTA rates and efficiencies.The combined experimental data illustrated that the water-soluble PAC acceptor was able to vectorially deliver the excited state energy stored in Cu-PS across the interface into the bulk aqueous solution by engaging in excited state electron transfer with methyl viologen acceptors.These results are important for remotely operating photoredox reactions in water while rendering a photosensitizer spatially isolated in the hydrophobic core of a micelle.}, number={12}, journal={ACS Applied Energy Materials}, publisher={American Chemical Society (ACS)}, author={Fayad, Remi and Bui, Anh Thy and Shepard, Samuel G. and Castellano, Felix N.}, year={2020}, month={Dec}, pages={12557–12564} }
 @article{awwad_bui_danilov_castellano_2020, title={Visible-Light-Initiated Free-Radical Polymerization by Homomolecular Triplet-Triplet Annihilation}, volume={6}, ISSN={2451-9294}, url={http://dx.doi.org/10.1016/j.chempr.2020.08.019}, DOI={10.1016/j.chempr.2020.08.019}, abstractNote={Polymerization reactions initiated by ultraviolet light are ubiquitous in scores of industrial applications but would markedly benefit from visible-light activation to overcome stability, energy consumption, light penetration, and sample geometry limitations. The current work leverages visible-light-driven homomolecular triplet-triplet annihilation (TTA) in zinc(II) meso-tetraphenylporphyrin (ZnTPP) to initiate facile free-radical polymerization in trimethylolpropane triacrylate (TMPTA) and methyl acrylate (MA) monomers through ultrafast electron transfer quenching. Selective Q-band (S1) excitation of ZnTPP in the green or yellow sensitizes TTA occurring between two 3ZnTPP∗ energized chromophores, ultimately generating the highly reducing S2 excited state on one ZnTPP molecule (Ered = −2.13 V versus saturated calomel electrode, SCE). Subsequently, this S2 state engages in electron transfer with TMPTA or MA, thereby initiating the radical polymerization process. Bimolecular electron transfer was confirmed through optically gated fluorescence upconversion. FT-IR and EPR spin-trapping experiments verified visible-light-initiated polymerization leading to the formation of well-defined macro- and microscopic objects.}, number={11}, journal={Chem}, publisher={Elsevier BV}, author={Awwad, Nancy and Bui, Anh Thy and Danilov, Evgeny O. and Castellano, Felix N.}, year={2020}, month={Nov}, pages={3071–3085} }
 @article{salehi_dong_shin_zhu_papa_thy bui_castellano_so_2019, title={Realization of high-efficiency fluorescent organic light-emitting diodes with low driving voltage}, volume={10}, ISSN={2041-1723}, url={http://dx.doi.org/10.1038/s41467-019-10260-7}, DOI={10.1038/s41467-019-10260-7}, abstractNote={Abstract}, number={1}, journal={Nature Communications}, publisher={Springer Science and Business Media LLC}, author={Salehi, Amin and Dong, Chen and Shin, Dong-Hun and Zhu, Liping and Papa, Christopher and Thy Bui, Anh and Castellano, Felix N. and So, Franky}, year={2019}, month={May} }
 @article{garakyaraghi_mccusker_khan_koutnik_bui_castellano_2018, title={Enhancing the Visible-Light Absorption and Excited-State Properties of Cu(I) MLCT Excited States}, volume={57}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/acs.inorgchem.7b03169}, DOI={10.1021/acs.inorgchem.7b03169}, abstractNote={A computationally inspired Cu(I) metal-to-ligand charge transfer (MLCT) chromophore, [Cu(sbmpep)2]+ (sbmpep = 2,9-di(sec-butyl)-3,8-dimethyl-4,7-di(phenylethynyl)-1,10-phenanthroline), was synthesized in seven total steps, prepared from either dichloro- or dibromophenanthroline precursors. Complete synthesis, structural characterization, and electrochemistry, in addition to static and dynamic photophysical properties of [Cu(sbmpep)2]+, are reported on all relevant time scales. UV-Vis absorption spectroscopy revealed significant increases in oscillator strength along with a concomitant bathochromic shift in the MLCT absorption bands with respect to structurally related model complexes (ε = 16 500 M-1 cm-1 at 491 nm). Strong red photoluminescence (Φ = 2.7%, λmax = 687 nm) was observed from [Cu(sbmpep)2]+, which featured an average excited-state lifetime of 1.4 μs in deaerated dichloromethane. Cyclic and differential pulse voltammetry revealed ∼300 mV positive shifts in the measured one-electron reversible reduction and oxidation waves in relation to a Cu(I) model complex possessing identical structural elements without the π-conjugated 4,7-substituents. The excited-state redox potential of [Cu(sbmpep)2]+ was estimated to be -1.36 V, a notably powerful reductant for driving photoredox chemistry. The combination of conventional and ultrafast transient  absorption and luminescence spectroscopy successfully map the excited-state dynamics of [Cu(sbmpep)2]+ from initial photoexcitation to the formation of the lowest-energy MLCT excited state and ultimately its relaxation to the ground state. This newly conceived molecule appears poised for photosensitization reactions involving energy and electron-transfer processes relevant to photochemical upconversion, photoredox catalysis, and solar fuels photochemistry.}, number={4}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Garakyaraghi, Sofia and McCusker, Catherine E. and Khan, Saba and Koutnik, Petr and Bui, Anh Thy and Castellano, Felix N.}, year={2018}, month={Feb}, pages={2296–2307} }