Photocatalytic decomposition of dispiro(diadamantane-1,2-dioxetane) initiated by Ce(ClO4)(3) in the excited state

被引:2
作者
Kazakov, VP
Voloshin, AI
Ostakhov, SS
Khusainova, IA
Zharinova, EV
机构
[1] Institute of Organic Chemistry, Ufa Research Center, Russian Academy of Sciences, 450054 Ufa
关键词
photocatalysis; quenching; energy transfer; dioxetane; cerium perchlorate;
D O I
10.1007/BF02495196
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Photocatalytic decomposition of dispiro(diadamantane-1,2-dioxetane) (1) to adamantanone (2) initiated by Ce(ClO4)(3) in the excited state in the MeCN-CHCl3 (2:1) mixture was studied. The bimolecular rate constants of quenching k(q) were determined from the kinetics of quenching of Ce3+* by dioxetane at different temperatures. The Arrhenius parameter; of the quenching were calculated from the temperature dependence of k(q):E-a = 3.2+/-0.3 kcal mol(-1) and logA = 1 1.6+0.6. The quantum yields of photolysis of 1 depending on its concentration and the rate constant of the chemical reaction of Ce3+* with 1 were determined. The latter coincides with k(q):k(ch) = (2.6+/-0.3).10(9) L mol(-1) s(-1) (T = 298 K). The fact that the maximum quantum yield of decomposition of dioxetane is equal to I indicates the absence of physical quenching of Ce3+* by dioxetane. It is believed that the electron transfer occurs in the reaction of Ce3+* with 1. Nonradiative deactivation of Ce3+* in solutions of MeCN and in MeCN-CHCl3 mixtures was studied. It is caused by the replacement of H2O molecules in the nearest coordination surroundings of Ce3+ by solvent molecules and reversible transfer of an electron to the ligand. The activation parameters of the nonradiative deactivation of Ce3+* were determined.
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页码:693 / 698
页数:6
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