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

作　　者：解永树[1] 刘清亮[1] 寇福平[2] 林瑞森[2] 

机构地区：[1]中国科技大学化学系,合肥230026 [2]浙江大学化学系,杭州310027

出　　处：《无机化学学报》2000年第3期461-466,共6页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金资助!(NO.29773041)

摘　　要：运用 ｐＨ电位滴定法，在 ２５±０．１℃　Ｔ， Ｉ＝０．１（ＫＮＯ_３）条件下，研究了 Ｃｕ（Ⅱ）与三吡啶胺（Ｌ’）和队（２’－羟基苄基）－二乙二胺（ＨＬ~２）的配位行为。结果表明，Ｌ’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 ｐ Ｋａ为 ７．５４。对于 ＨＬ~２，三个氮原子和酚氧负离子与 Ｃｕ（Ⅱ）配位，酚羟基离解常数 ｐ Ｋａ为４．４４。在２５±０．１℃，Ｉ＝０．１（ＫＮＯ_３）条件下，ｐＨ＝６～９（５０ｍｏｌ·Ｌ^（－１））范围内，用紫外、可见分光光度法研究了Ｌ~１的Ｃｕ（Ⅱ）配合物催化对－硝基苯酚乙酸酯（ＮＡ）水解动力学行为，发现配合物催化ＮＡ酯水解反应速率常数ｋ_（ＮＰ）与溶液 ｐＨ呈 Ｓｉｇｍｏｉｄａｌ型曲线， ｋ_（ＮＰ）最大值为 ２． ５３×１０^（－２）Ｌ· ｍｏｌ(－１)· ｓ(－１)。说明 Ｌ~１的 Ｃｕ（Ⅱ）配合物中的 Ｃｕ（Ⅱ）－ＯＨ~－是有效的亲核试剂，对底物ＮＡ酯的水解有较好的催化作用。The complexation processes of Cu (Ⅱ) with tripyridylamine(L^1 ) and N-(2'-hydroxybenzyl) -diethylenetriamine (HL^2) have been studied by PH potentiometric titration at 25±0. 1℃, I = 0.1 (KNO_3). The results indictate that, L^1 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 H_2O molecule with a pKa value of 7.54, which implies that the H_2O bound to Cu (Ⅱ) can readily deprotonate in the physiological pH range. Three nitrogen atoms of amino groups and one phenolic hydroxyl coordinate to Cu (Ⅱ) for HL^2. 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 (KNO_3) in 10% (V/ V) CH_3CN at pH 5. 5 - 9. 0(50mmol. L^(-1) buffers), and the second-rate constants k_(NP) for NA hydrolysis were obtained. The plot of k_(NP) of Cu (Ⅱ) (L^1) _2 vs pH has the characteristics of a Sigmoidal curve, with the maximum k_(NP) value of 2. 53 ×10^(-2)L. mol^(-1). s-1. The results suggest that the Cu (Ⅱ) -bound OH- acts as a good nucleophile and has good catalysis on NA ester hydrolysis.

关 键 词：三吡啶胺 四齿链酚胺 铜配合物 酯水解 

分 类 号：O614.121[理学—无机化学] O621.5[理学—化学]