Singlet-energy transfer in quadruple hydrogen-bonded oligo(p-phenylenevinylene)–fullerene dyads

Two novel supramolecular dyads consisting of an oligo(p-phenylenevinylene) (OPV) donor and fullerene (C60) acceptor are created via quadruple hydrogen bonding using self-complementary 2-ureido-4[1H]-pyrimidinone units. In the dyads, singlet-energy transfer from the excited OPV unit to the fullerene causes a strong quenching of the OPV fluorescence. The high association constant of the 2-ureido-4[1H]-pyrimidinone quadruple hydrogen-bonding unit results in high quenching factors (Qmax ≥ 90). The lower limit obtained for the rate constant for energy transfer (kEN ≥ 6 × 1010 s−1) is rationalized in terms of the Förster mechanism. Photoinduced electron transfer does not occur in these hydrogen-bonded dimers, even in polar solvents. The absence of charge separation is ascribed to a low electronic coupling between the donor and acceptor in the excited state as result of the long distance between the chromophores.