The kinetic study of electron transfer reactions of macrocyclic cobalt complexes with coordinated superoxo dicobalt complexes

• Main Authors: Ya-Hsuan Lee, 李亞瑄
• Other Authors: Shaoyung Lee
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/74703495205953440022

碩士 === 義守大學 === 化學工程學系暨生物技術與化學工程研究所 === 104 === Superoxide ion is one of the main reactive oxygens in organisms, but can’t exist in aqueous solution. The superoxide bonded transition metals are therefore widely used as a mimic in related biological research. Vitamin B12 is an important coenzyme in the human body. The electron transfer reaction of cobalt(II) macrocyclic complexes have been studied extensively due to the similar structure as vitamin B12 and the differences in oxidation potential in order to understand the mechanism of electron transfer reactions. The kinetics of the reactions between the superoxo di-cobalt complexes (((en)(dien)CoO)25+、((tetren)CoO)25+) and Cobalt(II) macrocycleic complexes ((Co(H2O)2Me6[14]4,11-dieneN42+)、(Co(H2O)2[15]aneN42+)、(Co(H2O)2[14]aneN42+)) are examined in the present study. The reactions were studied in pseudo-first order kinetic condition. Kinetic analysis found the rate law is: rate = k[superoxo][macro cyclic] The second order rate constants of the oxidation of cobalt(II) macrocyclic complexes with (en)(dien)CoO)25+at 25℃ are k = 75.8M-1s-1 (Co(H2O)2Me6[14]4,11-dieneN42+)、k = 14.4 M-1s-1 (Co(H2O)2[15]aneN42+). The reactions follow an outer-sphere electron transfer pathway based on Marcus theory. The dependence of the temperature and proton concentration as well was the thermodynamic activation parameters are discussed.