A molecular triad consisting of a diarylporphyrin (P)covalently linked to a carotenoid polyene (C) and afullerene (C
60) has been prepared and studied usingtime-resolved spectroscopic methods. In2-methyltetrahydrofuransolution, the triad undergoes photoinduced electron transfer to yieldC-P
+-C
60-, whichevolves into C
+-P-C
60- with an overall quantum yield of 0.14.This state decays by charge recombination to yield thecarotenoidtriplet state with a time constant of 170 ns. Even in a glass at77 K, C
+-P-C
60- isformed with a quantum yieldof ~0.10 and again decays mainly by charge recombination to give
3C-P-C
60. The fullerene triplet,formed throughnormal intersystem crossing, is also observed at 77 K. Thegeneration in the triad of a long-lived charge separatedstate by photoinduced electron transfer, the low-temperature electrontransfer behavior, and the formation of a tripletstate by charge recombination are phenomena previously observed mostlyin photosynthetic reaction centers.
