POTENTIAL-ENERGY SURFACES FOR ELECTRON-TRANSFER IN A SUPRAMOLECULAR TRIAD SYSTEM A(1)-D-A(2) IN A POLAR-SOLVENT

Electron-transfer processes in a supramolecular triad system A1-D-A2 in a polar solvent are theoretically investigated where D and A(i) stand for donor and acceptor subunits. Two relevant coordinates are introduced which represent the solvent polarization. Potential energy surfaces for the locally excited (LE) and charge-transfer (CT) states of the supramolecular system are calculated by using the dielectric continuum approximation for the solvent polarization. The model may easily be generalized or verified by using a more realistic molecular description of the solvent polarization. The correlation coefficient of the two solvent polarization coordinates is analyzed as a function of the distances between the donor and the two acceptors in the triad system. The expressions for the rates of electron transfer are derived in the nonadiabatic limit on the basis of the potential energy surfaces calculated. The decay rate coefficient of the locally excited state in the supramolecular system is calculated for different values of the free energy change in the case of nonadiabatic electron transfer.