TY - JOUR
T1 - Magnetic field effects and time-resolved EPR studies on the photogenerated biradicals in phenothiazine-C60 linked systems
T2 - Clarification of the mechanism of novel magnetic field effects by dependences of methylene chain length and temperature
AU - Moribe, Shinya
AU - Yonemura, Hiroaki
AU - Yamada, Sunao
N1 - Funding Information:
The authors are grateful to Mr. H. Horiuchi for the preparation of quartz cells for transient absorption spectral experiments. The authors also thank The Centre of Advanced Instrumental Analysis, Kyushu University, for 1 H NMR measurements. The present study was financially supported by the grants of the Inamori Foundation and the society for the support of Kyushu University, and by the Grant-in-Aids for Scientific Research: Priority Area of ‘Innovative Utilisation of Strong Magnetic Fields’ (Area 767, No. 15085203) and ‘Molecular Nano Dynamics’ (Area 432, No. 17034051), Scientific Research (C) (No. 17550131), and 21st Century COE Program ‘Function Innovation of Molecular Informatics’ from MEXT of the Japan.
PY - 2007/4/20
Y1 - 2007/4/20
N2 - Magnetic field effects (MFEs) on photogenerated biradical in phenothiazine (Ph)-C60 linked compound with four methylene group (Ph(4)C60) have been investigated. Transient absorption spectra showed photoinduced intramolecular electron-transfer reactions from the Ph to triplet excited state of C60(3 C60*) . With increasing magnetic field, the decay rate constant of the photogenerated biradical decreased steeply at lower magnetic fields (<0.2 T), and then recovered in the 0.2 T < H < 1.0 T region. Temperature dependence on the reverse phenomenon of the MFEs in Ph(4)C60 was clearly different from those in other linked compounds (Ph(n)C60 (n = 6, 8, 10, 12)). The present MFEs can be explained by the contribution of not only spin-lattice relaxation mechanism but also spin-spin relaxation mechanism related to {divides}2J{divides}. In time-resolved EPR measurements, the spectra in Ph(n)C60 (n = 4-12) are assigned to spin-correlated radical pairs. The methylene chain dependence of the time-resolved EPR spectra also supports the mechanism suggested in MFEs.
AB - Magnetic field effects (MFEs) on photogenerated biradical in phenothiazine (Ph)-C60 linked compound with four methylene group (Ph(4)C60) have been investigated. Transient absorption spectra showed photoinduced intramolecular electron-transfer reactions from the Ph to triplet excited state of C60(3 C60*) . With increasing magnetic field, the decay rate constant of the photogenerated biradical decreased steeply at lower magnetic fields (<0.2 T), and then recovered in the 0.2 T < H < 1.0 T region. Temperature dependence on the reverse phenomenon of the MFEs in Ph(4)C60 was clearly different from those in other linked compounds (Ph(n)C60 (n = 6, 8, 10, 12)). The present MFEs can be explained by the contribution of not only spin-lattice relaxation mechanism but also spin-spin relaxation mechanism related to {divides}2J{divides}. In time-resolved EPR measurements, the spectra in Ph(n)C60 (n = 4-12) are assigned to spin-correlated radical pairs. The methylene chain dependence of the time-resolved EPR spectra also supports the mechanism suggested in MFEs.
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U2 - 10.1016/j.chemphys.2007.03.009
DO - 10.1016/j.chemphys.2007.03.009
M3 - Article
AN - SCOPUS:34247333478
SN - 0301-0104
VL - 334
SP - 242
EP - 252
JO - Chemical Physics
JF - Chemical Physics
IS - 1-3
ER -