PHOTOINDUCED ELECTRON TRANSFER IN A CAROTENOBUCKMINSTERFULLERENE DYAD

Abstract

Abstract A carotenoid‐fullerene dyad has been synthesized by condensing a carotenoid amine with an acid group attached to C 60 by a cyclopropane‐based linkage. The lowest excited singlet state of the fullerene is strongly quenched by electron transfer from the carotenoid moiety to generate the charge‐separated species Car + ‐C 60 .‐ . In CS 2 solution Car + ‐C 60 .‐ has a rise time of 0.8 ps and decays by charge recombination in 534 ps. Light absorbed by either chromophore produces a high yield of Car + ‐C 60 .‐ , which implies that internal conversion in the carotenoid is negligible. The lowest triplet level in the dyad is localized on the carotenoid and is populated in low yield from the charge‐separated species. The sensitization of singlet oxygen by the fullerene component is effectively curtailed in the dyad.