【摘要】 用表面张力法及紫外光谱研究了β CD与非离子型表面活性剂TritonN - 10 1(TN)的包结体系。结果表明 ,TN的表面张力值及表观临界胶束浓度 (CMC )随 β CD浓度增加而增大 ,由于实验数据与所构建的 1∶1包结的数学模型完全相符 ,由此推测 β CD与TN形成 1∶1包结物。运用这一数学模型计算了TN与 β CD体系的包结平衡常数Ka(2 98K) ,结果表明Ka值与 β CD浓度成正比。通过Ka值还计算了包结体系自由能变化。紫外光谱结果表明 ,在 β CD浓度较小时 ,TN的疏水链优先进入 β CD内腔 ,而 β CD浓度较大时 ,TN的苯环部分也进入 β CD内腔更多还原

【Abstract】 The complexation of β-CD with a nonionic surfactant Triton N-101 (TN) has been studied by surface tension measurement and UV-visible spectroscopy. The surface tension curves and apparent critical micelle concentrations of TN in the presence of β-CD are higher than that in the absence of β-CD, which indicates that surface activity of TN decrease and formation of micelle is delayed because of the complexation of β-CD with TN. To clearly explicate the influences of β-CD-TN complexation on changes of surface tension and formation of micelle, the surface tension of fixed concentrations of TN mixed with β-CD is measured and the influences of β-CD on fixed concentrations of TN are discussed. When the concentration of TN is below its CMC, its surface tension increases with β-CD concentrations, and then remains at a maximum. But when the concentration of TN is above its CMC, its surface tension remains the same as γ CMC (surface tensions when TN concentrations are above its CMC) firstly, and then it increases with β-CD concentration, finally remains at a maximum. The association constants Ka of β-CD-TN system at 298 K are determined by the numerical method based on surface tension measurements that we developed. By measuring surface tensions of β-CD-TN systems, the plots of calculated S 0-\ value as a function of S 0/\ or S 0/\-1 give good straight line, which verified that, as assumed above, the supramolecular system stoichiometry is 1∶1 for the inclusion complexation. Ka of β-CD-TN system at 298 K is calculated from the slope of the straight line and Gibbs free energy change -ΔG 0 values of β-CD-TN systems have also been obtained. The results show that Ka depends on β-CD concentration, the higher of β-CD concentration, the larger of Ka values. Spectrophotometric titrations have been performed to show the interaction of this supramolecular system. As can be seen from the experiment results, when β-CD concentration is lower, the UV absorbance strength at 200, 222, 275 nm decreases with increasing β-CD concentration. But when the concentration of β-CD reaches at 8.0mmol/L, the absorbance at 275 nm shift to shorter wavelength. On the basis of this observation, we deduce that the hydrophobic chain of TN enter β-CD cavity mainly when β-CD concentration is lower; But when β-CD concentration is increased, the phenyl moiety of TN is located in a more hydrophobic environment, i.e., within the cyclodextrin cavity, rather than in the bulk aqueous solution. The models of the inclusion complexes are also designed based on experimental results.更多还原