紫外-可见光谱研究β-环糊精与β-胡萝卜素的包结作用

Study on the Inclusion Complexation Interaction of β-Cyclodextrin and β-Carotene by UV-Vis Spectra

用紫外 可见光谱研究了 β 环糊精与 β 胡萝卜素的包结作用 ,结果表明 ,3 2 5个 β 环糊精分子与 1个分子 β 胡萝卜素依据范德瓦尔斯作用力和疏水作用力发生包结作用 ,生成稳定的包结物 ,包结物和 β 环糊精的红外光谱也显示包结物的形成和存在。包结物适宜的制备条件为 :β 环糊精与 β 胡萝卜素的摩尔比为 3 2 5∶1,主客体溶液的浓度比为 12∶1;包结温度 30℃ ;反应时间 2h。用可见 紫外光谱测定的包结物的包结常数为 9 4 6× 10 11L·mol-1,包结物稳定。

cyclodextrin(β-CD), a kind of cyclic oligosaccharides, was found to possess a strong inclusion ability with β-carotene. The inclusion compounds of β-CD with β-carotene were prepared by the coprecipitation method, and studied by UV-Vis spectra of different mole ratio β-CD/β-carotene in the H 2O+ethanol solution (H 2O for β-CD, and ethanol for β-carotene). Equilibrium constant of inclusion compound was determined by UV-Vis spectra. The results indicate that 3.25 moles of β-CD can include one mole β-carotene to form inclusion compound by Van der Waals force and hydrophobic interaction etc. The optimum synthesis conditions of inclusion compound of β-CD with β-carotene is that the mole ratio of β-CD/β-carotene is 3.25∶1(mol/mol), the concentration ratio of β-CD H 2O solution/ β-carotene solution is 12∶1(mol·L -1/mol·L -1), and the time and temperature of inclusion reaction are 2 h and 30 ℃, respectively. Equilibrium constant of inclusion compound(K a) is 9.46×10 11 L·mol -1. The selective binding ability of β-CD with β-carotene has been discussed from the viewpoint of size/shape-fitting and geometry fitting between the host cavity and the guest molecule. The resistance to oxidation and photooxidation, and the solubility in H 2O of β-carotene were increased by inclusion with β-CD.