ENERGETICS OF CHARGE-TRANSFER REACTIONS IN SOLVENTS OF DIPOLAR AND HIGHER-ORDER MULTIPOLAR CHARACTER .1. THEORY

We extend a recent molecular theory of solvation dynamics to accommoda te static solvent effects on the energetics of charge transfer (CT) pr ocesses. Our theory is based on a simple renormalized linear response development which incorporates nonlinear aspects of equilibrium solvat ion. It can accommodate polarizable solvent molecules as well as the l imiting case represented by electronically rigid interaction site mode l (ISM) solvent molecules. We focus on the diabatic free energy profil es governing CT processes in solute donor-acceptor systems of chemical interest. By studying CT in ISM solution models we naturally cover bo th the short range and long range solute-solvent interactions, thereby enabling applications to CT in solvents of higher multipolar as well as dipolar character. We derive expressions for the key energetic para meters of a CT process; the solvent reorganization energy, the solvent contribution to the change in thermodynamic free energy, and the opti cal absorption and fluorescence frequencies. (C) 1996 American Institu te of Physics.