Magnetic field effect on an exciplex between N-vinyl carbazole grafted on cellulose acetate film and 1,4-dicyanobenzene

The present work emphasises the investigation of photoinduced electron tran sfer reaction between an electron-donor fluorophore, N-vinyl carbazole (VCZ ), grafted on a polymeric cellulose acetate film and an electron-acceptor, 1,4-dicyanobenzene, in the presence of an external magnetic field that serv es as a powerful tool to identify the spin states where the initial electro n transfer occurs and to modulate the course of the reaction as desire. Her e initial electron transfer occurs in the singlet spin state, and the forma tion of exciplex increases in the presence of magnetic field. The maximum f ield effect is obtained in the solvent with medium dielectric constant (eps ilon(max)) around 8.0. The epsilon(max) value indicates that the extent of charge transfer in this exciplex is less compared to other similar systems studied so far, owing to the characteristic binding of VCZ to the polymeric backbone through oxygen atom. (C) 1999 John Wiley & Sons, Inc.