Photochemical Redox Reactions of Copper(II)鈥揂lanine Complexes in Aqueous Solutions

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• 作者：Chen-Jui Lin ; Chao-Sheng Hsu ; Po-Yen Wang ; Yi-Liang Lin ; Yu-Shiu Lo ; Chien-Hou Wu
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：May 19, 2014
• 年：2014
• 卷：53
• 期：10
• 页码：4934-4943
• 全文大小：439K
• 年卷期：v.53,no.10(May 19, 2014)
• ISSN：1520-510X

文摘

The photochemical redox reactions of Cu(II)/alanine complexes have been studied in deaerated solutions over an extensive range of pH, Cu(II) concentration, and alanine concentration. Under irradiation, the ligand-to-metal charge transfer results in the reduction of Cu(II) to Cu(I) and the concomitant oxidation of alanine, which produces ammonia and acetaldehyde. Molar absorptivities and quantum yields of photoproducts for Cu(II)/alanine complexes at 313 nm are characterized mainly with the equilibrium Cu(II) speciation where the presence of simultaneously existing Cu(II) species is taken into account. By applying regression analysis, individual Cu(I) quantum yields are determined to be 0.094 卤 0.014 for the 1:1 complex (CuL) and 0.064 卤 0.012 for the 1:2 complex (CuL₂). Individual quantum yields of ammonia are 0.055 卤 0.007 for CuL and 0.036 卤 0.005 for CuL₂. Individual quantum yields of acetaldehyde are 0.030 卤 0.007 for CuL and 0.024 卤 0.007 for CuL₂. CuL always has larger quantum yields than CuL₂, which can be attributed to the Cu(II) stabilizing effect of the second ligand. For both CuL and CuL₂, the individual quantum yields of Cu(I), ammonia, and acetaldehyde are in the ratio of 1.8:1:0.7. A reaction mechanism for the formation of the observed photoproducts is proposed.