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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Experimental and Theoretical Studies on Halide Binding with a p-Xylyl-Based Azamacrocycle
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Experimental and Theoretical Studies on Halide Binding with a p-Xylyl-Based Azamacrocycle

机译：基于对二甲苯基的氮杂大环与卤化物结合的实验和理论研究

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摘要

A p-xylyl-based macrocycle L has been synthesized and its binding properties with halides have been investigated by H-1 NMR titrations, single crystal X-ray diffraction analysis, and density functional theory (DFT) calculations. As investigated by 1H NMR titrations, the ligand preferentially binds a halide in a 1:2 binding mode, with the association constants (in log K-2) of 2.82, 2.70, 2.28, and 2.20 for fluoride, chloride, bromide, and iodide, respectively. The overall binding trend was found to be in the order of fluoride > chloride > bromide > iodide, reflecting that the binding strength correlates with the relative basicity and size of the respective halide. Crystallographic studies indicate that the ligand forms 1:2 complexes with chloride, bromide and iodide. In the chloride complex, the ligand is hexaprotonated and each chloride is held via three NH.....Cl bonds. The ligand is tetraprotonated for the other complexes, where each halide is H-bonded to two secondary ammonium NH+ groups via NH.....X- bonds. The results of DFT calculations performed on [H(6)L](6+) at M062x/6-311G (d,p) level in both gas and solvent phases, suggest that the ligand binds halides with the binding energy in the order of F- > Cl- > Br- > I- , supporting the experimental data obtained from 1H NMR studies. Results from DFT calculations further indicate that a 1:2 binding is energetically more favorable than a 1:1 binding of the ligand.
机译：已合成了对二甲苯基大环化合物L，并通过H-1 NMR滴定，单晶X射线衍射分析和密度泛函理论（DFT）计算研究了其与卤化物的结合特性。通过1H NMR滴定研究，该配体优先以1：2结合模式结合卤化物，其中氟化物，氯化物，溴化物和碘化物的缔合常数（log K-2中）为2.82、2.70、2.28和2.20。 ， 分别。发现总的结合趋势为氟化物>氯化物>溴化物>碘化物，反映出结合强度与各个卤化物的相对碱性和大小相关。晶体学研究表明，该配体与氯化物，溴化物和碘化物形成1：2的配合物。在氯化物络合物中，配体被六质子化，并且每个氯化物通过三个NH..Cl键保持。对于其他配合物，该配体被四质子化，其中每个卤化物通过NH .... X-键与两个仲铵NH +基团H键合。在气相和溶剂相中均以[H （6） L]（6+）在M062x / 6-311G（d，p）水平上进行的DFT计算结果表明，配体与卤化物结合结合能按F-> Cl-> Br-> I-的顺序排列，支持从1H NMR研究获得的实验数据。 DFT计算的结果进一步表明，配体的1：2结合在能量上比1：1结合更为有利。

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