Institute of Chemical Sciences, University of Urbino, P.zza Rinascimento 6, I-61029 Urbino, Italy.
Inorg Chem. 2009 Nov 2;48(21):10424-34. doi: 10.1021/ic901459b.
The synthesis and characterization of the new polytopic ligands 1,14-bis(3,6,9-triaza-15-hydroxybicyclo[9.3.1]pentadeca-11,13,1(15)-trien-6-yl)-3,6,9,12-tetraazatetradecane L1, 1,15-bis(3,6,9-triaza-15-hydroxybicyclo[9.3.1]pentadeca-11,13,1(15)-trien-6-yl)-3,6,10,13-tetraazapentadecane L2, and 1,16-bis(3,6,9-triaza-15-hydroxybicyclo[9.3.1]pentadeca-11,13,1(15)-trien-6-yl)-3,7,10,14-tetraazahexadecane L3, containing two equal amino-phenol macrocycles spaced by several linear tetraamines, are reported. The basicity and coordination behavior toward the Cu(II) ion were potentiometrically determined in aqueous solution at 298.1 K. All the ligands show similar acid-base properties behaving as octaprotic bases in the examined pH range (pH = 2-12). The acid protons of L1-L3 cannot be removed under the experimental conditions used; thus, the main deprotonated species obtainable in aqueous solution are the neutral ligands, having amphionic character as demonstrated by UV-vis experiments. These species are able to form mono-, di-, and trinuclear Cu(II) complexes having stoichiometry CuL, Cu(2)L, and Cu(3)L, respectively, that can lose one or two protons giving rise to CuH(-1)L, Cu(2)H(-2)L, and Cu(3)H(-2)L. Depending on the used ligand to metal molar ratio, the mono-, di-, or trinuclear species prevail over the others in solution. Both di- and trinuclear complexes are able to add secondary ligands (such as OH(-)), and in some cases two Cu(II) can cooperate to stabilize them by coordinating the guest in a bridged conformation. The structure of the Cu(2)L3 cation was resolved by X-ray analysis of the {Cu(2)L3(4) x 3 H(2)O}(2) x H(2)O crystalline complex. It shows that each Cu(II) is penta-coordinated by one phenolate oxygen, two amine functions, belonging to one macrocyclic unit, and two amine functions of the spacer; in this species the distance between the two Cu(II) is about 5.3 A.
报告了新的多齿配体 1,14-双（3,6,9-三氮杂-15-羟基双环[9.3.1]十五烷-11,13,1（15）-三烯-6-基）-3,6,9,12-四氮杂十四烷 L1、1,15-双（3,6,9-三氮杂-15-羟基双环[9.3.1]十五烷-11,13,1（15）-三烯-6-基）-3,6,10,13-四氮杂十五烷 L2 和 1,16-双（3,6,9-三氮杂-15-羟基双环[9.3.1]十五烷-11,13,1（15）-三烯-6-基）-3,7,10,14-四氮杂十六烷 L3 的合成与表征，这些配体含有两个相等的氨基-苯酚大环，由几个线性四胺隔开。在 298.1 K 的水溶液中，通过电位法确定了基本碱度和配位行为对 Cu(II)离子的影响。所有配体均表现出相似的酸碱性质，在考察的 pH 范围内（pH = 2-12）表现为八质子碱。在所用的实验条件下，L1-L3 的酸质子不能被除去；因此，在水溶液中可获得的主要去质子化物种是中性配体，如紫外-可见实验所证明的，具有两性离子特性。这些物种能够形成具有化学计量比CuL、Cu(2)L和Cu(3)L的单核、双核和三核 Cu(II)配合物，它们可以失去一个或两个质子，生成CuH(-1)L、Cu(2)H(-2)L和Cu(3)H(-2)L。根据所用的配体与金属的摩尔比，单核、双核或三核物种在溶液中占优势。双核和三核配合物都能够添加次级配体（如 OH(-)），在某些情况下，两个 Cu(II)可以通过桥接构象配位稳定它们来相互配合。通过Cu(2)L3(4) x 3 H2O}2 x H2O 结晶配合物的 X 射线分析，解析了Cu(2)L3阳离子的结构。结果表明，每个 Cu(II)均由一个酚氧基、两个属于一个大环单元的胺功能和两个间隔基的胺功能五配位；在这种物质中，两个 Cu(II)之间的距离约为 5.3 Å。
