邻-甲氧基苯酚和α-,β-环糊精包合现象的理论与实验研究

通过紫外可见光谱法考察了水溶液中邻-甲氧基苯酚(o-Mop)和α-与β-环糊精(CD)的分子间相互作用, 利用Hildebrand-Benesi方程给出了两个包合物的稳定常数(K_s). 采用半经验PM3方法研究了α-,β-CD和o-Mop及其类似物苯酚(Phe)、丁香酚(Eug)之间的包络作用, 阐述了这些主客体包合作用过程中体系能量随主客体相对位置改变而变化的细节, 据此推断出主-客体包合物可能的分子结构, 计算了包合物的稳定化能(ΔE_s). 研究结果表明, 本文所选主客体体系而言, 当客体和同一种主体分子作用时, 超分子包合物的ΔE_s随着客体分子苯环上取代基团数目的增多而增加. 基于PM3方法优化得到的主-客体包合物在真空中的分子结构和通过实验方法在水溶液中测定的结构一致.

Experimental and Theoretical Study on the Inclusion Phenomena of o-Methoxyphenol with α- andβ-Cyclodextrin

The intermolecular interactions of α- and β-cyclodextrin (CD) as hosts with o-methoxyphenol (o-Mop) as guest in aqueous solution were investigated by UV-Vis spectroscopy. The stability constants K_s of the two inclusion complexes were calculated via Hildebrand-Benesi equation. Semi-empirical PM3 calculations were performed on the inclusion complexations of α-, β-CD with o-Mop and its analogs. The energy changes involved in these host-guest inclusion processes were clearly observed. Possible structures of the supramolecular complexes were presented and discussed. The stabilization energies (ΔE_s) of the inclusion complexes were also obtained. The value of ΔE_s of an inclusion system increased with increasing numbers of the substituents present on the phenyl ring of the guests selected in this study upon inclusion into the same host. The optimized host-guest supramolecular structures at energy minima, obtained by PM3 method in vacuo, were just accorded with the structures measured in aqueous solution.