用PM3分子轨道方法研究了α -环糊精的包合作用对环己烷构象平衡的影响。发现α -环糊精的包合作用可以改变环己烷的构象平衡。计算结果表明 ,虽然环己烷的椅式构象比船式构象稳定 1 8.5kJ·mol-1,但在α-环糊精的包合物中 ,船式环己烷包合物比椅式环己烷包合物稳定4.4kJ·mol-1。因此 ,超分子体系中客体分子的构象平衡不能简单地从其游离态的构象平衡外推得到 ,而应该考虑在超分子体系中分子间相互作用对构象的影响 The influence of inclusion of α - cyclodextrin on the conformational equilibrium of cyclohexane was studied by PM3 molecular orbital method. The inclusion of α - cyclodextrin was found to change the conformational equilibrium of cyclohexane. The calculated results show that although the chair conformation of cyclohexane is stable at 8.5 kJ · mol-1 compared with that of the boat conformation, in the inclusion complex of α-cyclodextrin, the ratio of the cyclohexane inclusion to the chair ring Hexane inclusion was stable at 4.4 kJ · mol -1. Therefore, the conformational equilibrium of guest molecules in a supramolecular system can not simply be extrapolated from its free-state conformational equilibrium, but the effect of intermolecular interactions on the conformation in a supramolecular system should be considered