High magnetic field effects on the lifetimes of radical pairs generated by the photoreduction of anthraquinone and n-alkyl anthraquinone-2-carboxylates in micellar solutions

被引:7
作者
Fujiwara, Y [1 ]
Yoda, K [1 ]
Tomonari, T [1 ]
Aoki, T [1 ]
Akimoto, Y [1 ]
Tanimoto, Y [1 ]
机构
[1] Hiroshima Univ, Fac Sci, Dept Chem, Higashihiroshima 7398526, Japan
关键词
D O I
10.1246/bcsj.72.1705
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
The magnetic field effects on the lifetimes of radical pairs (RPs) comprising anthrasemiquinone (AQH(.)) and alkyl radicals generated in Brij35, HDTCl, and SDS micellar solutions of anthraquinone (AQ) and n-alkyl anthraquinone-2- carboxylates (AQ-n) were studied by laser flash photolysis in high magnetic fields up to 13 T. The KP lifetimes of AQ and AQ-n in the three surfactants increased along with increasing the magnetic field from 0 to about 2 T. The RP lifetimes of AQ in Brij35 and HDTCl drastically decreased in a magnetic field from 3 to 13 T, whereas the RP lifetimes of AQ in SDS were almost constant in the same range of the magnetic field. The increase in the three surfactants was explained by spin-lattice relaxation (SLR) modulated by anisotropic hyperfine and electron dipole-dipole interactions. The drastic decrease in Brij35 and HDTCl was interpreted by SLR modulated by an anisotropic Zeeman interaction. The parameters of the anisotropic g-value and the rotational correlation time for an anisotropic Zeeman interaction were obtained. The constant RP lifetimes in SDS at a high magnetic field were interpreted referring to an escape process of AQH(.) from the micelle core.
引用
收藏
页码:1705 / 1715
页数:11
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