Photoinduced electron transfer in a fullerene–oligophenylenevinylene dyad

Abstract

A dialkylamino-subtituted oligophenylenevinylene (OPV) derivative bearing a fullerene subunit (F–D) has been prepared. The electrochemical properties of F–D have been investigated by cyclic voltammetry. Whereas the first reduction is centered on the C₆₀ unit, the oxidation is centered on the dialkylamino subunit of the OPV rod. In F–D, both the OPV and the fullerene-centered fluorescence bands are quenched and this suggests the presence of photoinduced electron transfer from the amino-substituted OPV to the carbon sphere. By means of bimolecular quenching experiments, transient absorption spectral fingerprints of the radical cationic species have been detected in the VIS (670 nm) and NIR (1300–1500 nm) regions, along with the much weaker fullerene anion band at λ_max = 1030 nm. Intramolecular photoinduced electron transfer occurs in the investigated dyad and a relatively long-lived charge-separated state has been detected, with a lifetime of 135 and 85 ns in toluene and benzonitrile, respectively. The longer lifetime in the less polar solvent suggests a Marcus inverted region behavior for the charge recombination process.