氨基甲酸酯型脱氧胆酸分子钳对中性分子的识别性能研究

利用差紫外光谱法考察了新型分子钳1～6对苯胺、对硝基苯胺、对甲氧基苯胺等中性分子的识别性能, 测定了25 ℃下, 在CHCl₃中主客体间的结合常数(K_a)和自由能变化(ΔG⁰). 结果表明, 所有分子钳主体对所考察的客体分子显示良好的识别作用, 主客体间形成1∶1型主客体络合物. 识别作用的主要推动力为多重氢键和π-π重叠等的作用. 讨论了主客体间形状、大小匹配和几何互补及识别模式等因素对识别能力的影响, 并利用核磁共振氢谱与计算机模拟作为辅助手段对实验结果进行了解释.

Recognition of Carbamate-Type Molecular Tweezers Derived from Deoxycholic Acid for Neutral Molecules

Molecular recognition properties of novel molecular tweezers 1～6 have been investigated by using aniline, p-nitroaniline and p-methoxyaniline. The association constants (K_a) and Gibbs free energy changes (ΔG⁰) have been measured by UV-Vis spectroscopic titration for inclusion complexes of these molecular tweezers with aromatic amines in CHCl₃ at 25 ℃. The results show that all the molecular tweezers have good recognition properties for the guests examined and the supramolecular complexes formed between the hosts and guests consist of 1∶1 host and guest molecules. The main driving forces are the multiple hydrogen bonding and π-π stacking interaction between host and guest molecules. The molecular recognition ability is discussed in terms of the size/shape-fit and geometrical complementary relationship as well as the recognition model between host and guest molecules. ¹H NMR spectroscopy and computer-aided study have been employed to elucidate the experimental results.