Synthesis, stability, and crystal structure studies of some Ca2+, Cu2+ and Zn2+ complexes of macrocyclic polyamino carboxylates
Synthesis, stability, and crystal structure studies of some Ca2+, Cu2+ and Zn2+ complexes of macrocyclic polyamino carboxylates
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DOI：
10.1021/ic00130a012
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发表时间：
1995-12-20
影响因子：
4.6
通讯作者：
Gougoutas, JZ
中科院分区：
文献类型：
--
作者：
Kumar, K;Tweedle, MF;Gougoutas, JZ
三种配体 DO3A (1,4,7,10-四氮杂环十二烷-1,4,7-三乙酸)、HP-DO3A (10-(2-羟丙基)-1,4,7,10-四氮杂环十二烷-1,4,7-三乙酸) 和 DO3MA (1R,4R,7R)-α,α',α 的配合物的稳定常数''-三甲基-1,4,7,10-四氮杂环十二烷-1,4,7-三乙酸）与Ca2+、Cu2+和Zn2+在25.0+/-0.1℃和mu=0.1（TMACl）下测量。具有五元螯合环的钙和钆络合物遵循线性 log K-ML 与 Sigma pK(a) 以及 log K-GdL 与 log K-CaL 相关性。表明 Ca2+ 和 Gd3+ 具有相似的配位行为。 log K-ML 和 Z/r（HP-DO3A 络合物的金属离子上的电荷密度）之间的线性相关性与 Ca2+ 与 Gd3+ 络合物的较低稳定常数一致。计算了 Gd3+ 相对于其他金属离子的总体选择性常数。通过 X 射线单晶分析确定了三种水合形式的 [Ca(HP-DO3A)](2) 的晶体结构：C-2 对称三核结构。 Ca(H2O)(4)[Ca(HP-DO3A)](2) . 10H(2)O，中心对称六核结构 {Ca(H2O);[Ca(HP-DO34A)](2) . 3H(2)O}(2) 和 C-2 对称三核结构 Ca(H2O)(4)[Ca(HP-DO3A)](2) 。 2H(2)O，它是通过第一个结构在 22 摄氏度下拓扑脱水形成的。大环配体 [3333] 的构象及其与嵌入的钙离子的配位在所有形式中几乎都是相同的。 HCu(DO3A) 晶体结构中的大环结构采用四边形 [2334] 构象，其中四个氮和氧夹在两个几乎平行的平面之间。两个相对的羧酸酯臂与 Cu(II) 原子配位。
The stability constants of the complexes of three ligands, DO3A (1,4,7,10-tetrazacyclododecane-1,4,7-triacetic acid), HP-DO3A (10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid), and DO3MA (1R,4R,7R)-alpha,alpha',alpha ''-trimethyl-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid), with Ca2+, Cu2+, and Zn2+ were measured at 25.0 +/- 0.1 degrees C and mu = 0.1 (TMACl). Calcium and gadolinium complexes which have five-membered chelate rings follow linear log K-ML vs Sigma pK(a) and log K-GdL vs log K-CaL correlations. suggesting Ca2+ and Gd3+ have similar coordination behavior. A linear correlation between log K-ML and Z/r (charge density on the metal ion, for HP-DO3A complexes is consistent with the lower stability constant of the Ca2+ vs Gd3+ complex. The overall selectivity constants for Gd3+ over other metal ions were calculated. The crystal structures of three hydrated forms of [Ca(HP-DO3A)](2) were determined by X-ray single-crystal analysis: a C-2 symmetric trinuclear structure. Ca(H2O)(4)[Ca(HP-DO3A)](2) . 10H(2)O, a centrosymmetric hexanuclear structure. {Ca(H2O);[Ca(HP-DO34A)](2) . 3H(2)O}(2), and a C-2 symmetric trinuclear structure, Ca(H2O)(4)[Ca(HP-DO3A)](2) . 2H(2)O, which is formed through topotactic dehydration of the first structure at 22 degrees C. The conformations of the macrocyclic ligands, [3333], and their coordination to the embedded calcium ions are virtually identical in all forms. The embedded calcium is sandwiched between two nearly parallel planes of four nitrogens and oxygens. The macrocyclic ring in the crystal structure of HCu(DO3A) adopts a quadrangular [2334] conformation in which the four nitrogens and two opposite carboxylate arms are coordinated to the Cu(II) atom.