LONG-LIVED PHOTOINDUCED CHARGE SEPARATION IN A BRIDGED C-60-PORPHYRINDYAD

Long-range photoinduced energy and electron transfer have been investi gated in a novel dyad containing a zinc tetraarylporphyrin (P-Zn) dono r and a C-60 acceptor separated by a saturated norbomylogous bridge ni ne sigma bonds in length (P-Zn-9 sigma-C-60). In non-polar solvents si nglet-singlet energy transfer from P-Zn to C-60 is observed but in ben zonitrile efficient (> 90%) charge separation occurs with a rate const ant of 1 x 10(10) sec(-1) to yield P-Zn(.+)-9 sigma-C-60(.-). The char ge separated state exhibits a remarkably long lifetime for a dyad of 4 20 ns. This behaviour is discussed with reference to the energetics, d ynamics and orbital symmetry properties of the states involved.