Synthesis and Reactivity of Nickel Complexes with various 4-Hydroxy-L-Prolinol Ligands Relevant to the Active Site of Nickel Superoxide Dismutase

• Main Authors: Lin Yu Chen, 林昱辰
• Other Authors: Lee Way Zen
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/95337102960913138409

碩士 === 國立臺灣師範大學 === 化學系 === 101 === Nickel-containing superoxide dismutase (NiSOD) has been found in the Streptomyces species, and marine cyanobacteria in recent years. NiSOD can catalyze the disproportionation of the superoxide anion into hydrogen peroxide and dioxygen avoiding cell damage from oxidative stress. In order to mimic the active site of NiSOD, various pentadentate lignads, BMPORP (R = H, TMS, TPS) and H2BDPPOH, were designed and prepared. As these ligands reacted with [Ni(CH3CN)6](ClO4)2, four complexes, [Ni(BMPOHP)(CH3CN)](ClO4)2 (1), [Ni(BMPOTMSP)- (CH3CN)](ClO4)2 (2), [Ni(BMPOTPSP)(CH3CN)](ClO4)2 (3) and Ni(BDPPOH) (4) were formed. Complexes 1, 2, 3 and 4 were characterized by UV/vis spectroscopy, cyclic voltammetry (CV) and X-ray crystallograph. CV measurements for complex 1, 2 and 3 displayed an irreversible reduction in MeCN at -1.01, -1.04 and -1.09 V vs Ag/Ag+, respectively. It shows that [NiII(BMPORP)CH3CN](ClO4)2 cannot be oxidized to NiIII complexes. However, CV measurements of complex 4 displayed a reversible event centered at 0.52 V vs Ag/Ag+ suggesting that complex 4 could be oxidized by [CP2Fe]PF6. The NiIII complex, [Ni(BDPPOH)]PF6 (5), characterized by UV/vis spectroscopy, CV and EPR, was synthesized by oxidation of complex 4. Complex 5 could oxidize KO2 to form O2 gas and itself was reduced to complex 4. The superoxide dismutase activity, half maximal inhibitory concentration (IC50) for dismutasing superoxide anion, of complex 5 was 1.8 × 10-4 M. The IC50 reveals complex 5 possessing SOD activity.