Molecular design of tetraazamacrocyclic derivatives bearing a spirobenzopyran and three carboxymethyl moieties and their metal-ion complexing behavior
Molecular design of tetraazamacrocyclic derivatives bearing a spirobenzopyran and three carboxymethyl moieties and their metal-ion complexing behavior
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DOI：
10.2116/analsci.24.463
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发表时间：
2008-04-01
影响因子：
1.6
通讯作者：
Kimura, Keiichi
中科院分区：
文献类型：
--
作者：
Machitani, Koji;Sakamoto, Hidefurni;Kimura, Keiichi
合成了含有一个螺苯并吡喃和三个羧甲基结构的四氮杂环十二烷和四氮杂环十四烷衍生物I和2，以及含有一个螺苯并吡喃和四个羧甲基结构的二亚乙基三胺衍生物3。这些配体的螺苯并吡喃部分的异构化行为进行了研究，通过紫外-可见分光光度法在水溶液中含有各种金属离子在中性pH值。这些配体形成稳定的1：1配合物与镧系元素离子，而螺苯并吡喃部分异构化，其相应的mercury形式，即使在黑暗条件下。在含有镧系元素离子的水溶液中，1或2的吸收光谱显示出显着的蓝移，而在可见光区的最大吸收波长处的荧光增强，这种变化是由于异构化的mercury形式的螺苯并吡喃部分。这些结果表明，由于镧系离子的高电荷密度，汞部分的酚盐阴离子与络合部分结合的镧系离子非常强烈地相互作用。与此相反，大环配体与过渡金属离子如Cu 2+和Zn 2+的络合会降低汞的吸光度。这一结果表明，大环配体1和2仅通过氨基羧酸根与过渡金属离子形成络合物，而汞的酚根离子不能参与络合。密度泛函理论计算也证实了这一结论。
Tetraazacyclododecane and tetraazacyclotetradecane derivatives bearing a spirobenzopyran and three carboxymethyl moieties, I and 2, and a diethylenetriamine derivative bearing a spirobenzopyran and four carboxymethyl moieties 3 were synthesized. The isomerization behaviors based on the spirobenzopyran moiety of these ligands were studied by UV-visible spectrophotometry in aqueous solutions containing various metal ions at neutral pH. These ligands formed stable 1:1 complexes with lanthanide ions, while the spirobenzopyran moiety was isomerized to its corresponding merocyanine form even under dark conditions. In aqueous solutions containing a lanthanide ion, the absorption spectra of 1 or 2 showed remarkable blue shifts, while absorbances at the maximum absorption wavelengths in the visible region were enhanced; such changes are attributable to the isomerization to the merocyanine form of the spirobenzopyran moiety. These results suggest that the phenolate anion of the merocyanine moiety interacts very strongly with a lanthanide ion bound by the complexing moiety because of the high charge density of lanthanide ions. In contrast, the absorbance of merocyanine form was decreased by the complexation of the macrocyclic ligand with transition metal ions, such as Cu2+ and Zn2+. This result indicates that macrocyclic ligands, 1 and 2, formed complexes with transition metal ions only by the aminocarboxylate moieties, and the phenolate ion of merocyanine moiety was not able to participate in the complexation. This conclusion was also demonstrated by density functional theory calculations.