Professor Sharon Hammes-Schiffer, University of Illinois at Urbana-Champaign.  "Proton-Coupled Electron Transfer:  Theory and Application."  Theoretical Chemistry Seminar.

Proton-Coupled Electron Transfer: Theory and Applications

Sharon Hammes-Schiffer

Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801; shs3@illinois.edu

Proton-coupled electron transfer (PCET) reactions play a vital role in a wide range of chemical and biological processes. This talk will present a general theory for PCET reactions. The quantum mechanical effects of the active electrons and transferring proton(s), as well as the motions of the proton donor-acceptor mode and solvent or protein environment, are included in this theory. This formulation enables the calculation of rate constants and kinetic isotope effects for comparison to experiment. This theory has also been extended to electrochemical processes. Applications to PCET reactions in solution, enzymes, and electrochemical systems will be presented. Studies of the enzyme soybean lipoxygenase provide a physical explanation for the experimental observation of unusually high kinetic isotope effects for C-H bond activation at room temperature.  Investigations of molecular electrocatalysts for hydrogen production identify the thermodynamically and kinetically favorable mechanisms and guide the theoretical design of more effective molecular electrocatalysts. In addition, recent developments of theoretical approaches for simulating the ultrafast nonequilibrium dynamics of photoinduced PCET processes will be presented. Quantum mechanical/molecular mechanical nonadiabatic dynamics simulations enable the investigation of the relaxation pathways following photoexcitation. These calculations provide insights into the roles of proton vibrational relaxation and nonequilibrium solvent dynamics in photoinduced PCET processes in solution and photoreceptor proteins.