新型Schiff碱分子钳对中性分子的识别性能研究

Recognition of Neutral Molecules by Novel Schiff Base Molecular Tweezers

采用差紫外光谱法考察了3种新型 Schiff 碱分子钳对-系列二苯甲酮、芳香二胺的识别性能．测定了主客体间的结合常数(K_a)和自由能变化(△G^0)．结果表明，分子钳对所考察的客体显示良好的识别作用，主客体间形成1∶1型超分子配合物．讨论了识别作用的推动力与形状、大小匹配和几何互补等因素对形成主客体配合物的影响，并利用核磁氢谱与计算机模拟作为辅助手段对主要的实验结果与现象进行了解释．

Molecular recognition properties of three novel molecular tweezers as receptors have been investigated using diphenyl ketone and aromatic diamines. The association constants ( K-a) and Gibbs free energy changes (DeltaG(0)) have been measured by UV-visible spectroscopic titration on the complexes of these molecular tweezers with some aromatic diamines and diphenyl ketone. The results show that the supramolecular complexes formed between the tweezers and various substrates consist of 1: 1 host and guest molecules. The molecular recognition ability of the receptors for diphenyl ketone and aromatic diamines is discussed in terms of size/shape-fit, complementary geometrical relationship, and the weak intermolecular forces. H-1 NMR spectroscopy and computer-aided studies have been employed to elucidate the binding behavior of these molecular tweezers. Molecular modeling and H-1 NMR spectroscopy studies suggest that the multiple pi- pi stacking and van der Waals interaction may be the main driving forces in molecular recognition. The size/shape-fit and geometyical complementary relationship between the receptor and the substrate play a pivotal role in the inclusion complextion of these guests with the molecular tweezers.