角鲨烯/γ-环糊精包合物制备及分子模拟

Preparation and Molecular Simulation of Squalene/γ-Cyclodextrin Inclusion Complex

采用水溶液法结合冷冻干燥法制备角鲨烯/γ-环糊精包合物,应用相溶解度法、傅里叶变换红外光谱及氢谱核磁共振对包合物进行表征,并对包合物分子结构进行模拟.结果表明,当角鲨烯过量时,形成的包合物主客物质的量比大多为1:1;而当γ-环糊精过量时,可形成平均主客物质的量比为3.45:1的包合物.包合物的分子结构为角鲨烯链状分子将γ-环糊精环状分子均匀地"串联"在一起,且随着主客物质的量比增加,包合物分子结构趋于稳定.由于角鲨烯分子链长所限,理论上最佳主客物质的量比为4:1.包合物的包合常数随温度升高而增大,在55℃条件下最大可达1778.086 L/mol,且在此温度下最大可使角鲨烯的水溶性提高为原来的309倍.根据能量变化推断,熵增加是角鲨烯分子进入γ-环糊精空腔的主要驱动力.

A squalene/γ-cyclodextrin inclusion complex was prepared by aqueous solution method combined with freezedrying. The inclusion complex was characterized by phase solubility method, Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance (1H NMR), and its molecular structure was simulated. The results showed that when excess squalene was available, the molar ratio of the host to the guest in the inclusion complex was mostly 1:1. When excess γ-cyclodextrin was available, an inclusion complex with an average molar ratio of the host to the guest of 3.45:1 was formed. The molecular structure of the inclusion complex was organized by uniform linear connection of the cyclic γ-cyclodextrin molecules to each other via the chain-like squalene molecules and its tended to be stable as the molar ratio of the host to the guest increased. Because the molecular chain length of squalene is limited, the optimum host-to-guest mole ratio is theoretically 4:1. The inclusion constant increased with increasing temperature, and could reach a maximum of 1 778.086 L/mol at 55 ℃;the maximum water solubility of squalene could be increased by 309 times at this temperature. It is inferred from the change in energy that entropy increase is the main driving force for squalene molecules to enter the γ-cyclodextrin cavity.