Solvation evidence for the lifetime of donor–acceptor complexes

Abstract

A correlation is established between the excitation energy of the donor–acceptor system hexamethylbenzene–tetracyanoethylene and solvent polarisability, but in analogous systems with stronger donors the correlation decreases or fails. These findings are interpreted in terms of charge-transfer excitation of transient species produced during random collision of donor with acceptor molecules interacting with the solvent through dipole–induced dipole forces.