Photoinduced Electron Transfer in Donor-linked Fullerenes

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We have prepared ferrocene-porphyrin dimer-fullerene triad where meso, meso-linked porphyrindimer is incorporated successfully into a charge separation unit as photosynthetic multistep electron transfer model for the first time. The triad reveals photoinduced electron transfer from the porphyrin dimer excited singlet state to the C_<60>, followed by charge-shift from the ferrocene to the porphyrin dimer radical cation, to produce the ferricenium ion-C<60> radical ion pair with a high quantum yield (0.71-0.88) as well as a long-lived charge-separated lifetime (16-83 μs) depending on the solvent. It should be emphasized here that the charge-separated lifetime of the present triad has been prolonged by replacing porphyrin monomer with porphyrin dimer without reducing the quantum yield significantly. The charge-separated lifetime is governed by stepwise charge recombination rather than direct charge recombination.