β-环糊精与质子化及非质子化环氧苯乙烷超分子体系的理论研究

Theoretical Study on the Supramolecular System of β-CD-Styrene Oxide and β-CD-Protonated Styrene Oxide

采用分子动力学模拟和量子化学计算方法对β-CD-环氧苯乙烷和质子化的β-CD-环氧苯乙烷形成的超分子体系进行了理论研究.结果表明,质子化的环氧苯乙烷的苯基朝向β-CD的小口时体系最稳定,此时主客体的相互吸引作用相对较大;而对于非质子化的环氧苯乙烷,虽然其苯基朝向-βCD的大口较稳定,但由于主客体之间具有较大的排斥能,最终得到的包结物仍可能以苯基朝向-βCD的小口为主.电荷密度拓扑分析发现,当苯基取向β-CD的小口方向时,质子化以及非质子化的环氧苯乙烷都能与位于-βCD大口边沿的羟基形成氢键.因此,环氧苯乙烷在-βCD内相中的定位作用主要得益于诸如氢键以及偶极等较强的分子间相互作用.

The molecular dynamic simulation and quantum chemistry methods were employed to study the supramolecular systems of β-CD-styrene oxide and β-CD-protonated styrene oxide. The results show that, when the phenyl group of protonated styrene oxide points to the secondary rim of β-CD, the system is inclined to be more stable and its attractive energy is relatively larger. But the case for styrene oxide is in disagreement with the protonated partner. However, in the view of kinetics, the phenyl group of styrene oxide maybe finally point to the secondary rim of β-CD due to its comparatively less repulsive energy in the complex. The property of electron density analyzed by topological study indicates that hydrogen bond was formed between the host and guest molecules when the phenyl group of guest molecules points to the secondary rim of β-CD. As a result, it is suggested that the orientation effect on styrene oxide in the inner phase of β-CD might mostly be attributed to the interactions between the host and guest molecules, such as H-bond, dipole action, etc..