Radiative and nonradiative electron transfer in donor-acceptor phenoxazineand phenothiazine derivatives

Radiative and nonradiative electron transfer (exemplified by the CT fluores cence 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 q uantities relevant for the radiative electron transfer in the Marcus invert ed region. Using a nonadiabatic theory of electron transfer and the latter parameters, the rate constants for nonradiative electron transfer can be pr edicted. Electronic coupling elements V-0 between the (CT)-C-1 state and th e ground state obtained from the radiative rates are in agreement with thos e calculated from the simple LCAO MO model which assumes that V-0 are mainl y determined by the interactions between the atoms forming the A-D bond. (C ) 1999 Elsevier Science B.V. All rights reserved.