Theoretical investigation of proton-coupled electron transfer reactions in condensed phases

A comprehensive theoretical investigation of proton-coupled electron transfer (PCET) reactions in various systems is presented. The study is motivated by experimental results showing that proton motion coupled to electron transfer is important throughout chemistry and biology. PCET is a crucial step in a wide range of biological processes such as photosynthesis and respiration. Moreover, PCET occurs in numerous enzyme reactions, solid state materials and electrostatic processes. The theoretical study of PCET reactions elucidates the fundamental principles of the process and provides additional insight for the experimental observations.; We use a multistate continuum theory to investigate the mechanism of PCET in the systems of interest. In this formulation the solvent is represented as a dielectric continuum, the solute is described by an empirical valence bond (EVB) model, and the transferring proton is treated quantum mechanically. This theoretical approach allows us to calculate free energy surfaces, rates and kinetic isotope effects for the PCET reactions, as well as to predict trends that can be verified experimentally.