| 三吡啶胺和四齿链酚胺配体与Cu(Ⅱ)配位性质及其配合物催化酯水解研究 |
| Coordination of Cu (Ⅱ) with Tripyridylamine and a Tetradentate Ligand and Hydrolysis of 4-Nitrophenyl Acetate Catalyzed by these Complexes |
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| 摘要: 运用pH电位滴定法,在25±0.1℃ T,I=0.1(KNO3)条件下,研究了Cu(Ⅱ)与三吡啶胺(L1)和队(2'-羟基苄基)-二乙二胺(HL2)的配位行为。结果表明,L1以二齿的形式和Cu(Ⅱ)形成稳定的2:1(L:M)配合物。其配位水分子的离解常数pKa为7.54.对于HL2,三个氮原子和酚氧负离子与Cu(Ⅱ)配位,酚羟基离解常数pKa为4.44.在25±0.1℃,I=0.1(KNO |
| 关键词: 金属水解酶 亲核试剂 催化水解 |
| 基金项目: 国家自然科学基金资助(NO．29773041) |
| Abstract: The complexation processes of Cu (Ⅱ) with tripyridylamine(L1) and N-(2'-hydroxybenzyl) -diethylenetriamine (HL2) have been studied by PHpotentiometric titration at 25±0.1℃, I = 0.1 (KNO3).The results indictate that, L1 is a bidentate ligand and only forms stable Cu (Ⅱ) complex with a ratio L: Cu (Ⅱ) = 2:1.In the complex Cu (Ⅱ) is able to combine a H2Omolecule with a pKa value of 7.54, which implies that the H2O bound to Cu (Ⅱ) can readily deprotonate in the physiological pHrange.Three nitrogen atoms of amino groups and one phenolic hydroxyl coordinate to Cu (Ⅱ) for HL2.The coordinated hydroxyl can dissociate with a pKa value of 4.44.The kinetics of p-nitrophenyl acetate (NA) hydrolysis catalyzed by the complexes was determined spectrophotometrically at 25 ±0.1℃ and I = 0.1 (KNO3) in 10% (V/ V) CH3CN at pH 5.5～9.0(50mmol·L-1 buffers), and the second-rate constants kNP for NA hydrolysis were obtained.The plot of kNP of Cu (Ⅱ) (L1) 2 vs pHhas the characteristics of a Sigmoidal curve, with the maximum kNP value of 2.53 ×10-2L·mol-1·s-1.The results suggest that the Cu (Ⅱ) -bound OH- acts as a good nucleophile and has good catalysis on NAester hydrolysis. |
| Keywords: metallohydrolases nucleophiles catalytic hydrolysis |
| 投稿时间：1999-09-09 修订日期：1999-12-20 |
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| 解永树,寇福平,林瑞森,刘清亮.三吡啶胺和四齿链酚胺配体与Cu(Ⅱ)配位性质及其配合物催化酯水解研究[J].无机化学学报,2000,16(3):461-466. |
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