Radiative and nonradiative electron transfer in donor–acceptor phenoxazine and phenothiazine derivatives

Abstract

Radiative and nonradiative electron transfer (exemplified by the CT fluorescence and nonradiative charge recombination process in the singlet manifold, respectively) in a series of donor–acceptor phenoxazine and phenothiazine derivatives is reported. An analysis of the CT fluorescence leads to the quantities relevant for the radiative electron transfer in the Marcus inverted region. Using a nonadiabatic theory of electron transfer and the latter parameters, the rate constants for nonradiative electron transfer can be predicted. Electronic coupling elements V 0 between the 1 CT state and the ground state obtained from the radiative rates are in agreement with those calculated from the simple LCAO MO model which assumes that V 0 are mainly determined by the interactions between the atoms forming the A–D bond.