Inhibition of the formation and decay of stilbene core radical cations by the dendron during the photoinduced electron transfer

摘要

Formation and decay processes of stilbene core radical cation (ST./) during the photoinduced electron transfer have been studied for a series of stilbene bearing benzyl ether-type dendrons (D). ST./ and the radical cation of peripheral dendron (D-./) were generated by intermolecular hole transfer from biphenyl radical cation. which was venerated from photoinduced electron transfer from biphenyl to the singlet-excited 9, 10-dicyanoanthracene in a mixture of acetonitrile and 1.2-dichloroethane (3:1). An intramolecular dimer radical cation of benzyl groups at the terminal of stilbene dendrimer was indicated as a hole trapping site. Subsequent hole transfer from the trapping site to the core ST generated ST./. The shielding effects of D depending on the dendrimer generation on the growth and decay of ST./ were observed. It was revealed for the first time that D acts as the hole trapping site and the hole conductor on the way of the exothermic hole transfer from the terminal of D to the central core ST. We also found that D inhibits the charge recombination with 9, 10-dicyanoanthracene radical anion because of the steric hindrance.