LASIR, CNRS UMR8516, Université Lille 1 Sciences et Technologies , Bât C5 - 59 655 Villeneuve d'Ascq Cedex - France.
J Phys Chem A. 2014 Apr 10;118(14):2646-55. doi: 10.1021/jp412291z. Epub 2014 Apr 2.
UV-visible absorption spectroscopy combined with quantum chemical calculations and, notably, Time-Dependent Density Functional Theory were used to probe the structure of metal complexes with esculetin in dilute aqueous solution, at pH = 5. For the 1:1 complex formation, the studied metal ions can be classified according to their complexing power: aluminum(III) > copper(II) > lead(II). For the three complexes, a chelate is formed with the fully deprotonated catechol moiety and an absorption band is observed at the same wavelength. In all cases, a pronounced ionic character is calculated for metal-ligand bonds. However, the complexes differ in their coordination sphere. Copper and lead are bound to two water molecules leading to a square plane geometry and a hemidirected complex, respectively, whereas aluminum atom has an octahedral environment involving three water molecules and a hydroxide ion. For Al(III) only, a 2:1 complex is observed, and the involvement of an aluminum dimer was evidenced.
采用紫外-可见吸收光谱结合量子化学计算，特别是时间依赖密度泛函理论，研究了在 pH = 5 的稀水溶液中，esculetin 与金属配合物的结构。对于 1:1 配合物的形成，根据其配位能力，研究的金属离子可以分为：三价铝 > 二价铜 > 二价铅。对于这三种配合物，均形成了完全去质子化的儿茶酚部分的螯合物，并在相同的波长处观察到一个吸收带。在所有情况下，计算得到金属-配体键均具有明显的离子特性。然而，这些配合物在其配位球上有所不同。铜和铅分别与两个水分子结合，形成平面正方形几何形状和半指向配合物，而铝原子具有包含三个水分子和一个氢氧根离子的八面体环境。仅对于三价铝，观察到 2:1 配合物，并且证明存在铝二聚体的参与。
