ON THE EXCIPLEX FORMATION IN THE ENERGY-TRANSFER FROM AROMATIC-HYDROCARBONS TO CRYSTAL VIOLET

The interaction of a triphenyl methane (TPM) dye: crystal violet (CV) with the triplet state (S-3) Of the aromatic molecules biphenyl, p-te rphenyl or anthracene was studied by pulse radiolytic kinetic spectrop hotometry. in each case, studies of time-resolved spectra and kinetics showed that an exciplex between sensitiser triplet and ground state o f CV is formed as an intermediate before the former dissociates to giv e triplet state of CV, [S-3 + CV (kb)reversible arrow(kf) (3)(S..CV)* -->(k3) S + (CV)-C-3]. A detailed kinetic analysis has been carried out to evaluate various kinetic kb parameters. The equilibrium constan t, K (k(f)/k(b)), was found to be 1.8 X 10(4) dm(3) mol(-1), 1.53 X 10 (4) dm(3) mol(-1) and 1.32 X 10(4) dm(3) mol(-1) in the case of biphen yl, p-terphenyl and anthracene sensitiser triplet states, respectively . (C) 1998 Elsevier Science S.A.