Visible light induced photo-oxidation of water. Formation of intermediary hydroxyl radicals through the photoexcited triplet state of perfluorophenazine
作者:Takayuki Kitamura、Hiroyuki Fudemoto、Yuji Wada、Kei Murakoshi、Mitsuhiro Kusaba、Nobuaki Nakashima、Tetsuro Majima、Shozo Yanagida
DOI:10.1039/a604920f
日期:——
1,2,3,4,5,6,7,8-Octafluorophenazine (F-Phen) has an absorption
spectrum in the longer wavelength extending to the visible-light
region and has a more positive oxidation potential than for
unfluorinated phenazine. F-Phen has been photolysed with water in
acetonitrile under visible-light irradiation to produce
stoichiometrically 1,3,4,5,6,7,8-heptafluoro-2-hydroxyphenazine
(F-Phen-2-OH). Photolysis of F-Phen with water in the presence of
benzene leads to the formation of phenol followed by the disappearance
of F-Phen. EPR analysis and laser flash photolysis reveal that the
photoexcited triplet state of F-Phen participates in water oxidation
to hydroxyl radicals with concurrent conversion to F-Phen-2-OH. The
mechanism is discussed with the results of semi-empirical molecular
orbital calculations.
1,2,3,4,5,6,7,8-八氟吩嗪(F-Phen)的吸收光谱波长较长,可延伸至可见光区域,与未氟化的吩嗪相比,其氧化电位更正。在可见光的照射下,F-Phen 与乙腈中的水发生光解反应,按比例生成 1,3,4,5,6,7,8-七氟-2-羟基吩嗪(F-Phen-2-OH)。在苯的存在下,F-Phen 与水发生光解,生成苯酚,随后 F-Phen 消失。EPR 分析和激光闪烁光解显示,F-Phen 的光激发三重态参与了水氧化成羟自由基的过程,并同时转化成 F-Phen-2-OH。该机制与半经验分子轨道计算的结果进行了讨论。