Triplet Energy Transfer of the Intramolecular System Having Benzophenone and Dibenzazepine at the Chain Ends: Chain Length Dependence

Article abstract of DOI:10.1021/j100162a009

Intramolecular triplet-triplet energy transfer in a series of polymethylene chains having a benzophenone (BP) group as an energy donor and a dibenzazepine (DBA) group as an energy acceptor (BP-O(CH2)nCO-DBA) has been studied by phosphorescence measurement and nanosecond laser photolysis.In a rigid solution and PMMA matrix, the quantum yield of triplet-triplet energy transfer is close to unity for the chain lengths shorter than n = 5.On the basis of the through-space mechanism of energy transfer, phosphorescence decay curves were analyzed by Dexter's equation in which the distribution of donor-acceptor distance was calculated by the conformational energy analysis.The results of the simulation were in fairly good agreement with the experimentally observed decay curves.The rate constant of triplet-triplet energy transfer is strongly dependent on the chain length, i.e., about one-tenth derease per every methylene unit, and the rate is much smaller than that of singlet-singlet energy transfer.