TY - JOUR
T1 - EPR investigation of photoinduced radical pair formation and decay to a triple state in a carotene-porphyrin-fullerene triad
AU - Carbonera, Donatella
AU - Di Valentin, Marilena
AU - Corvaja, Carlo
AU - Agostini, Giancarlo
AU - Giacometti, Giovanni
AU - Liddell, Paul A.
AU - Kuciauskas, Darius
AU - Moore, Ana
AU - Moore, Thomas
AU - Gust, Devens
PY - 1998/5/13
Y1 - 1998/5/13
N2 - The photochemistry of a molecular triad consisting of a porphyrin (P) covalently linked to a carotenoid polyene (C) and a fullerene derivative (C60) has been studied at 20 K by time-resolved EPR spectroscopy following laser excitation. Excitation of the porphyrin moiety yields C-1P-C60 which decays by photoinduced electron transfer to yield C-P.+-C60.-. This state rapidly evolves into a final charge-separated state C.+-P-C60.-, whose spin polarized EPR signal was observed and simulated. There is a weak exchange interaction between the electrons in the radical pair (J - 1.2 G). The C.+-P-C60.- state decays to give the carotenoid triplet in high yield with a time constant to 1.2 μs. The spin polarization of 3C-P-C60 is characteristic of a triple formed by charge recombination of a single- derived radical pair. The kinetics of the decay of 3C-P-C60 to the ground state were also determined. The photoinduced electron transfer from an excited singlet state at low temperature and the high yield of charge recombination to a spin-polarized triplet mimic similar processes observed in photosynthetic reaction centers.
AB - The photochemistry of a molecular triad consisting of a porphyrin (P) covalently linked to a carotenoid polyene (C) and a fullerene derivative (C60) has been studied at 20 K by time-resolved EPR spectroscopy following laser excitation. Excitation of the porphyrin moiety yields C-1P-C60 which decays by photoinduced electron transfer to yield C-P.+-C60.-. This state rapidly evolves into a final charge-separated state C.+-P-C60.-, whose spin polarized EPR signal was observed and simulated. There is a weak exchange interaction between the electrons in the radical pair (J - 1.2 G). The C.+-P-C60.- state decays to give the carotenoid triplet in high yield with a time constant to 1.2 μs. The spin polarization of 3C-P-C60 is characteristic of a triple formed by charge recombination of a single- derived radical pair. The kinetics of the decay of 3C-P-C60 to the ground state were also determined. The photoinduced electron transfer from an excited singlet state at low temperature and the high yield of charge recombination to a spin-polarized triplet mimic similar processes observed in photosynthetic reaction centers.
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U2 - 10.1021/ja9712074
DO - 10.1021/ja9712074
M3 - Article
AN - SCOPUS:0032513729
SN - 0002-7863
VL - 120
SP - 4398
EP - 4405
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 18
ER -