Exciplex Formation and Electron Transfer in a Vinyl Copolymer

Abstract

Studies have been made on the exciplex formation in a vinyl copolymer, its characteristics, and the electron-transfer process in polar solvents using a p-N,N-dimethylaminostyrene-p-cyanostyrene copolymer. The copolymer was found to exhibit a much more intense intramolecular exciplex fluorescence than the model N,N-dimethylaniline–cyanobenzene system where the intermolecular exciplex formation occurs. The copolymer system has an advantage over the model system in the exciplex formation process but suffers a disadvantage in the process of ionic dissociation in polar solvents. The ionic dissociation for the copolymer system, however, was attained in the presence of a stronger electron acceptor, p-dicyanobenzene, in polar solvents. The results of flash photolysis and exciplex quenching indicated that the p-dicyanobenzene, anion radical was generated by successive electron transfer from the cyanobenzene anion radical portion in the copolymer to p-dicyanobenzene. That is, in the copolymer system, the interaction between the pendant donor and acceptor groups is favored even in the presence of a stronger electron acceptor.