Recent Advances in Intramolecular Electronic Energy Transfer

Abstract

A study of intramolecular energy transfer (Intra-ET) in a specifically designed1 series of bichromophoric molecules consisting of cyclic α-diketones incorporating an ortho-, meta-, or para substituted benzene ring (Fig. 1) is reported. Most spectroscopic properties of these molecules are described by a superposition of those of their constituent chromophores. Unique for the bichromophoric molecule is the fact that, depending on the molecular geometry, energy absorbed by the aromatic chromophore is transferred in part to the α-diketone and both chromophores emit their characteristic fluorescence spectra2. An extensive study was made of the intramolecular electronic energy transfer process in solution as a function of temperature3. The results (Fig. 2) indicate that the transfer efficiency is strongly structure dependent suggesting that Dexter type exchange interaction is responsible for Intra-ET between close chromophores in a bichromophoric molecule. The thermal dependence observed in some cases is atributed to conformational factors.