Photonic switching of photoinduced electron transfer in a dihydropyrene-porphyrin-fullerene molecular triad

Photonic control of photoinduced electron transfer has been demonstrated in a dimethyldihydropyrene (DHP) porphyrin (P) fullerene (C-60) molecular triad. In the DHP-P-C-60 form of the triad, excitation of the porphyrin moiety is followed by photoinduced electron transfer to give a DHP-P.+-C-60(.-) charge-separated state, which evolves by a charge shift reaction to DHP.+-P-C-60(.-). This final state has a lifetime of 2 mus and is formed in an overall yield of 94%. Visible (greater than or equal to300 nm) irradiation of the triad leads to photoisomerization of the DHP moiety to the cyclophanediene (CPD). Excitation of the porphyrin moiety of CPD-P-C-60 produces a short-lived