Photoinduced electron transfer within porphyrin-containing poly(amide) dendrimers

The synthesis and photophysical characterization of a series of free base porphyrin-containing polyamide dendrimers terminated with anthraquinone groups (FbP-Ga-AQ(n)(), a = 1-3, n = 12, 36, 108) are described. Substantial quenching (58-75%) of the porphyrin fluorescence of FbP-Ga-AQ(n)() is observed when compared to the analogous ethyl-terminated dendrimers (FbP-Ga-Et(n)()) in steady-state fluorescence experiments and is attributed to intramolecular electron transfer. Time-resolved fluorescence experiments were fit to 2-3 exponentials, indicating multiple orientations for electron transfer, consistent with the flexible nature of these dendrimers.