Proton Coupled Electron Transfer. Redox Cofactors, Catalysis, and Photochemistry

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In this award, the Chemical Catalysis program of the Chemistry Division supports Professor Thomas Meyer of The University of North Carolina at Chapel Hill for the research on "Proton Coupled Electron Transfer (PCET). Redox Cofactors, Catalysis, and Photochemistry." PCET is a chemical process that involves movement of a negatively charged electron that is facilitated by the simultaneous transfer of a positively charged hydrogen ion. This process plays an important role in both chemical and biological systems. However, its implications for catalysis, energy conversion, and for biological function and disease are only beginning to be fully appreciated. In fact, a full understanding of the elementary processes in PCET has not been achieved. This project explores the details of the PCET mechanisms that help dictate biological function and involves both experimental and theoretical studies. In addition, PCET is being extended toward the preparation of valuable organic chemicals. Graduate students and postdoctoral research fellows are actively involved in the project as are undergraduate students from "Climate LEAP," a summer program that targets underrepresented groups.The research focuses on two important themes. One is an investigation of the role of PCET in key redox cofactors of biology with an eye toward elucidating its role in the larger sweep of enzymatic reactivity. In the other, recently uncovered roles for PCET in excited state chemistry are being extended to map its role in molecular photochemistry, and, potentially, its role in chemical synthesis and energy conversion. In the first, the PCET mechanism will be explored in concert with functional analysis of oxido-reductase protein structures with application of a computational protocol based on the Rosetta energy function. PCET and electron proton transfer (EPT) will be investigated in quinone/hydroquinone interconversion and in the isoalloxazine functional group of flavins and the dihydropyridine/pyridinium functional group of nictotinamides. Investigations on redox cofactors will be extended to modified electrodes to explore PCET/EPT at electrode interfaces with possible applications in analysis and electrocatalysis. Finally, excited state PCET will be extended to H-atom and photoEPT reactivity in solution and on the surfaces of mesoscopic, nanostructured oxide films with an eye toward photoelectrochemical organic synthesis.