Syntheses of Rigid and Semirigid Molecules for Investigations of Photoinduced Electron Transfer Reactions
摘要:
Investigations of electron transfer reactions in donor-spacer-acceptor (DSA) molecules posessing small numbers of reactive conformations have significantly increased understanding of factors that control transfer rate constants. The syntheses of polynorbornane-based DSA molecules 12, 16, 20, 26, 30, and 34 and heptacyclotetradecane-based DSA molecules 40, 47, 51, and 60 are described. These molecules have been used to explore the effects of electronic symmetry, solvent electronic structure, and temperature on photoinduced electron transfer reactions.
A series of derivatives of the titled compound with donor and acceptor substituents were prepared. Efficient fluorescence quenching was observed for the molecules in which donor and acceptor pi -chromophores are coplanar. Charge recombination of the radical ion pairs resulted in broad charge transfer bands centered at ca. 510 nm. Twisting the donor and acceptor chromophores 90 degrees with respect to each other seemed to retard the electron transfer process. (C) 2000 Elsevier Science Ltd. All rights reserved.