手性不对称脲联苯二甲酸分子钳对中性分子的识别性能研究

Recognition of neutral molecules by chiral diphenic acid-based molecular tweezers containing unsymmetrically disubstituted urea unit

用差紫外光谱滴定法考察了新型分子钳1～5对苯胺、对甲氧基苯胺、对氨基苯乙酮等中性分子的识别性能,测定了主客体间的结合常数(ka)和自由能变化(ΔG°).结果表明,分子钳主体对所考察的客体分子显示良好的识别作的协同作用.讨论了主体与客体间形状、大小匹配和几何互补等因素,对形成超分子配合物的影响,并利用计算机分子模拟作为辅助手段对实验结果与现象进行了解释.

Molecular recognition properties of new molecular tweezers based on diphenic acid 1- 5 have been investigated by using aniline, p-methoxyaniline and p-aminoacetophenone. The association constants （ kα ） and Gibbs free energy changes （△G°） have been determined by UV-visible spectroscopic titration for inclusion complexes of these molecular tweezers with aromatic amines in CHCl3 at 25℃. The results indicate that the supramolecular complexes formed between the hosts and guests consist of 1： 1 host and guest molecules. The greatest association constant reached 5119.23 L·mol^-1. The main driving forces come from the hydrogen bonding and π-π stacking force in molecular recognition. The molecular recognition ability is discussed from the viewpoint of the size/shape-fit and geometrical complementary relationship between host and guest molecules. Computer-aided study has been employed to elucidate the binding behavior of these molecular tweezers.