EXCITATION OF C-60, SOLUBILIZED IN WATER BY TRITON X-100 AND GAMMA-CYCLODEXTRIN, AND SUBSEQUENT CHARGE SEPARATION VIA REDUCTIVE QUENCHING

The excitation of C60 incorporated in triton X-100 micelles has been studied by laser flash photolysis. Reductive quenching of triplet-excited C-3(60) by diazabicyclooctane (DABCO) has been established in the micellar assembly, in aqueous solution of the fullerene embedded in gamma-cyclodextrin, in alcohols and non-polar toluene. In aqueous media potassium hexacyanoferrate (II) and potassium iodide have been employed in the reductive quenching process as well. The C60-. radical anion in all investigations has been characterized by its IR absorption. The formation and the half-life of C60-. have been shown to be strongly dependent on the polarity of the environment. By utilizing DABCO as a quencher a half-life of 440 mus has been observed in the micellar assembly, while the respective values in propan-2-ol and butan-1-ol are 110 and 98 mus, respectively. In aqueous solution the radical anion gamma-CD/C60-. decays with a half-life of 59 mus and, in contrast, in the non-polar toluene no formation of any C60-. could be detected. The results are consistent with a charge-separated C-3(60)-quencher contact pair.