大环三胺铜(Ⅱ)配合物催化羧酸酯水解动力学研究  

Kinetics of Carboxyester Hydrolysis Promoted by Copper(Ⅱ) Complex of Macrocyclic Triamine

作　　者：郭惠[1] 王晓莉[1] 李珺[1] 张逢星[1] 

机构地区：[1]西北大学合成与天然功能分子化学教育部重点实验室,西北大学化学系,西安710069

出　　处：《无机化学学报》2008年第1期37-42,共6页Chinese Journal of Inorganic Chemistry

摘　　要：合成了大环三胺配体-1,4,7-三氮杂环癸烷([10]aneN3),并对文献方法进行了改进,简化了步骤,节省了溶剂。在25±0.1℃,离子强度I=0.10mol.L-1(KNO3)条件下,采用pH电位滴定法,测定了配体的质子化常数以及与Cu(Ⅱ)离子的配位平衡常数,讨论了配体与金属离子的配位情况。通过分光光度法,在pH值7～9范围内(2×10-4mol.L-1tris做为缓冲溶液),研究了配合物催化对-硝基苯酚乙酸酯(NA)水解动力学行为,得到了NA酯的水解速率常数kcat。结果表明催化水解速率对底物(NA)及配合物浓度均呈一级反应,水解反应遵循速率方程v=(kcatcCu2++kOH-cOH-+…)cNA;在中性和弱碱性条件下能很好的催化NA的水解,pH=9.19时,催化速率常数达到了4.405×10-2mol-1.L.s-1,优于国际上同类研究报道的结果;催化反应受酸碱平衡控制。结合滴定结果,提出了催化反应机理。Macrocyclic triamine ligand 1,4,7-Triazacyclododecane（tacd）was synthesized according to the literature with the improvement on the scheme of the synthesis in order to saving the solvent and predigesting the process.By pH potentiometer titration,protonation constants of the ligand and equilibrium constants of Cu（Ⅱ）complex with the ligand were determined.The kinetics of p-nitrophenyl acetate（NA）hydrolysis catalyzed by the complex was determined spectrophotometrically at 25±0.1 ℃ and at pH values of 7.0～9.0,and the catalytic-rate constants kcat for NA hydrolysis were obtained.The results indicate that the catalytic rate follow the law of rate v=（kcatcCu^2＋＋kOH-cOH^-＋…）cNA and the hydrolysis process is controlled by an acid-base equilibrium.At pH value of 9.16,kcat reaches 4.405×10^-2 mol^-1·L·s^-1 which is better than the catalysis of the similar macrocyclic triamine complexes.The results suggest that this complex can be used as the model of hydrolytic metalloenzyme.The mechanism of hydrolysi was also studied by pH potentiometer titration.

关 键 词：大环三胺 水解酶 催化 速率常数 

分 类 号：O614.12[理学—无机化学] O612[理学—化学]