Chen Jia-Mei, Ruan Wen-Juan, Meng Liang, Gao Feng, Zhu Zhi-Ang
Department of Chemistry, Nankai University, Tianjin 300071, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2008 Nov 1;71(1):191-8. doi: 10.1016/j.saa.2007.12.007. Epub 2007 Dec 23.
Metal (M = Zn(II), Ni(II), Cu(II)) complexes with tetradentate Schiff base ligand, bis(pyrrol-2-ylmethyleneamine)phenyl, has been synthesized and characterized by elemental analyses, 1H NMR, mass spectra and UV-vis spectra. The standard association constants (Ktheta) and the thermodynamic parameters (Delta(r)Hmtheta,Delta(r)Smtheta,Delta(r)Gmtheta) for axial coordination of imidazole derivatives with these Shiff base complexes were measured with UV-vis spectrophotometric titration. The decrease of enthalpy is found to be the drive of the axial coordination. Our Schiff base complexes can incorporate two axial ligands, except 2-Et-4-MeIm with two big substituents of great steric bulk according to stoichiometry of 1:1. ZnL displays high selectively binding to imidazole due to the steric bulk effect. Supporting density functional theory (DFT) calculations have been undertaken on B3LYP/6-31G(d) level.
已合成了金属（M = Zn(II)、Ni(II)、Cu(II)）与四齿席夫碱配体双（吡咯-2-基亚甲基胺）苯形成的配合物，并通过元素分析、1H NMR、质谱和紫外可见光谱对其进行了表征。用紫外可见分光光度滴定法测定了咪唑衍生物与这些席夫碱配合物轴向配位的标准缔合常数（Kθ）和热力学参数（ΔrHmθ、ΔrSmθ、ΔrGmθ）。发现焓的降低是轴向配位的驱动力。根据1:1的化学计量比，除了具有两个大的空间位阻取代基的2-Et-4-MeIm外，我们的席夫碱配合物可以结合两个轴向配体。由于空间位阻效应，ZnL对咪唑表现出高选择性结合。已在B3LYP/6-31G(d)水平上进行了支持密度泛函理论（DFT）计算。
