TY - JOUR
T1 - Reaction center models in liquid crystals
T2 - Identification of paramagnetic intermediates
AU - Di Valentin, Marilena
AU - Bisol, Arianna
AU - Giacometti, Giovanni
AU - Carbonera, Donatella
AU - Agostini, Giancarlo
AU - Liddell, Paul A.
AU - Moore, Ana
AU - Moore, Thomas
AU - Gust, Devens
N1 - Funding Information:
This work was supported by the TMR EC project no. CT98-0214, by the CNR project no. CNRG004079 and by the U. S. NSF, grant no. CHE-0078835. We thank Prof. Alberta Ferrarini for helpful discussion. *To whom correspondence should be addressed (m.divalentin@chfi.unipd.it).
PY - 2003
Y1 - 2003
N2 - Photoinduced charge separation and recombination to the triplet state in a carotene (C) porphyrin (P) fullerene (C 60) triad have been followed by time-resolved electron paramagnetic resonance (EPR). The electron transfer process has been studied at different temperatures in both a glassy isotropic matrix (2-methyltetrahydrofuran) and uniaxial liquid crystal (E-7). In both media, the triad undergoes two-step photoinduced electron transfer, with the generation of a long-lived charge separated state (C* +-P-C 60* -), and charge recombination to the triplet state, localized in the carotene moiety. The carotenoid triplet state is initially polarized according to the mechanism of recombination of a radical pair with singlet precursor. Both the photoinduced spin-correlated radical pair and the carotene triplet are observed in E-7 starting from the glass to the liquid crystal phase. The exchange interaction between the electrons in the radical pair (J = 1.2 Gauss) has been evaluated by simulation of the EPR spectrum in the isotropic glass and comparison with the corresponding spectrum in the oriented medium.
AB - Photoinduced charge separation and recombination to the triplet state in a carotene (C) porphyrin (P) fullerene (C 60) triad have been followed by time-resolved electron paramagnetic resonance (EPR). The electron transfer process has been studied at different temperatures in both a glassy isotropic matrix (2-methyltetrahydrofuran) and uniaxial liquid crystal (E-7). In both media, the triad undergoes two-step photoinduced electron transfer, with the generation of a long-lived charge separated state (C* +-P-C 60* -), and charge recombination to the triplet state, localized in the carotene moiety. The carotenoid triplet state is initially polarized according to the mechanism of recombination of a radical pair with singlet precursor. Both the photoinduced spin-correlated radical pair and the carotene triplet are observed in E-7 starting from the glass to the liquid crystal phase. The exchange interaction between the electrons in the radical pair (J = 1.2 Gauss) has been evaluated by simulation of the EPR spectrum in the isotropic glass and comparison with the corresponding spectrum in the oriented medium.
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U2 - 10.1080/15421400390193648
DO - 10.1080/15421400390193648
M3 - Article
AN - SCOPUS:10444289895
SN - 1542-1406
VL - 394
SP - 19
EP - 30
JO - Molecular Crystals and Liquid Crystals
JF - Molecular Crystals and Liquid Crystals
ER -