Photoinduced electron transfer in dendritic macromolecules. 1. Intermolecular electron transfer

Photoinduced electron transfer in a series of dendritic macromolecules 1-6 has been investigated by a fluorescence quenching method. Both electron accepters and electron donors quench the fluorescence of these dendrimers efficiently. The Stern-Volmer quenching constants for higher generation dendrimers for quenching by 1,4-diazabicyclo[2.2.2]octane (DABCO) are unusually large. Steady-state as well as time-resolved fluorescence spectroscopic studies indicate that there is a large contribution from static quenching in higher generation dendrimers. The evidence for ground-state complex formation has been obtained from a Benesi-Hildebrand plot for higher generation dendrimers and DABCO. Higher generation dendrimers also tend to form exciplexes with DABCO in tetrahydrofuran.