The dynamics of photoinduced intramolecular electron/charge transfer of the model compounds with different degrees of electronic interactions between combined donor-acceptor groups in polar solvents have been investigated using femtosecond-picosecond time resolved absorption and fluorescence spectroscopy. In the systems showing a simple one-electron transfer from the excited state localized in the acceptor to the intramolecular ion-pair state, time dependencies of the electron transfer reaction were expressed by an extended exponential function, although the main part of the reaction can be approximated by an exponential function, from which we can estimate the approximate electron transfer time of the compounds. In some compounds, the approximate electron transfer times are found to be faster than the solvation time and the longitudinal dielectric relaxation time of the solvents. The possible mechanisms responsible for the extended exponential behavior are discussed.

In the strongly interacting donor-acceptor systems, the electronic delocalization interaction in the TICT state is affected by the solvent orientational motion as well as the geometrical structure between donor and acceptor.