Radiative electron transfer in planar donor-acceptor quinoxaline derivatives

Synthetic and spectral studies have been performed for a family of electron donor-acceptor (D-A) quinoxaline derivatives possessing an aromatic amine as an electron donor. A photophysical behaviour of the compounds with an in ternal degree of freedom for internal D-A rotation and their rigid analogue s with a fixed planar conformation appears to be very similar. Electronic t ransition dipole moments related to the charge-transfer (CT) absorption and fluorescence are determined by both the direct interactions between the (C T)-C-1 and ground states and by the contributions from the locally excited configurations. The radiative properties of the D-A systems under study can be explained in terms of the simple model which assumes that the electroni c coupling elements are mainly determined by the interactions between the a toms forming the A-D bond. (C) 2000 Elsevier Science B.V. All rights reserv ed.