Photoinduced electron transfer in a covalent benzo[a] pyrene diol epoxide—2′-deoxyguanosine complex

The fluorescence of the pyrenyl chromophore in a covalently linked benzo [a] pyrene diol epoxide-N22′-deoxyguanosine complex and in noncovalent 7,8,9,10-tetrahydroxytetrahydrobenzo[a] pyrene—deoxyguanosine complexes, is strongly quenched in aqueous solution by a photoinduced electron transfer mechanism. The results of transient absorption spectroscopy experiments with picosecond laser pulse excitation are consistent with the formation of a short-lived charge transfer exciplex (nanosecond time scale) in which the pyrenyl residue acts as an electron acceptor.