Professor Matthew B. Zimmt, of the Department of Chemistry at Brown University, is supported by the Organic Dynamics Program and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate for his exploration of solvent-mediated electronic coupling in electron transfer and energy transfer reactions. The mediation of electronic coupling between an electron donor and an electron acceptor by the surrounding medium represents an essential element in chemical and biological electron transfer. Through the synthesis of a family of molecules bearing donor and acceptor moieties attached to a common rigid spacer, Professor Zimmt explores the role of intervening solvents in electron transfer processes, addressing the generality of solvent-mediated coupling in electron-mediated and hole-mediated processes, the dependence of solvent-mediated coupling on solvent properties and on donor-bridge-acceptor electronic symmetry, the effects of interference between solvent- and bond-mediated coupling, and the relevance of solvent-mediated electronic coupling to triplet energy transfer. Reactions in which an electron is transferred from one molecule to another form the basis of a wide range of important chemical and biological processes, including the photosynthetic capture and utilization of energy from sunlight by plants. With the support of the Organic Dynamics Program and the Office of Multidisciplinary Activities of the Mathematical and Physical Sciences Directorate, Professor Matthew B. Zimmt, of the Department of Chemistry at Brown University, studies chemical factors influencing the transfer of an electron from one molecule to another. By constructing molecules designed to hold the donor and the acceptor of the electron with a well-defined orientation and spacing with respect to one-another, Professor Zimmt examines the role of intervening solvent molecules in mediating the electron transfer process. These model studies shed light on the fundamental factors controlling biological electron transfer reactions and are of additional relevance to areas such as the design and construction of molecular-scale electronic devices.
