Distance dependence of photoinduced electron transfer through non-conjugated bridges

Abstract

Picosecond time-resolved emission studies of a series of molecules containing an electron donor-acceptor pair interconnected by a series of rigid non-conjugated bridges reveal the occurrence of very fast photoinduced intramolecular electron transfer. The length of the bridge was varied to provide donor-acceptor centre-to-centre separations ranging from 8.1 to 13.3 Å (edge-to-edge 5 to 10.2 Å). At centre-to-centre separations up to 10.7 Å the rate of photoinduced electron transfer exceeded 5×10 10 s −1 (τ<20 ps); at the largest separation, 13.3 Å, the rate was 1.47×10 10 s −1 (τ = 68 ps).