Excitation of C 60, solubilized in water by triton X-100 and γ-cyclodextrin, and subsequent charge separation via reductive quenching

Abstract

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