荧光光谱法研究葫芦[7]脲与6-巯嘌呤和腺嘌呤的包结作用

采用荧光光谱法分别研究了葫芦7]脲(CB7])对6-巯嘌呤(6-MP)和腺嘌呤(ADP)的包结作用。实验考察了时间、pH值以及温度对荧光强度和包结作用的影响,利用Benesi-Hildebrand方程分别计算出6-MP和ADP与CB7]的包结常数。结果表明:酸度对体系的包结有明显的影响。在pH值为8.0和2.0左右时,6-MP和ADP分别具有稳定和最佳激发和发射波长,随着CB7]浓度的增大,体系的荧光强度都有明显增强,包结作用迅速(小于5 min)。实验得出CB7]与6-MP和ADP的包结比均为1∶1,在298 K时的包结常数分别为3.6797×102L·mol-1和2.2033×102L·mol-1。通过热力学参数的变化,探讨了维系包结物稳定性的主要作用力。CB7]是葫芦脲家族中水溶性最强的主体分子,作为一种安全低毒的药物载体极具潜力。

Study on the Inclusion Interactions of Cucurbit[7]uril with 6-Mercaptopurine and Adenine by Fluorescence Spectrometric Method

The inclusion interactions of cucurbit7]uril(CB7]) with 6-mercaptopurine(6-MP)and adenine(ADP) were studied by fluorescence spectrometric method.Several effect factors such as time,the pH value and temperature on the fluorescence intensity and the stability of the complex were investigated.The complex constants of CB7] with 6-MP and ADP were determined according to the Benesi-Hildebrand equation,respectively.The results indicated that the pH value had a significant effect on the inclusion interactions.6-MP and ADP had the optimal and stable excitation and emission wavelength as the pH value were 8.0 for 6-MP and 2.0 for ADP within 5 min.With the increasing of the concentrations of CB7],the fluorescence of the two complexes increased obviously.The inclusion constants were 3.6797×102 L·mol-1 for 6-MP-CB7] and 2.2033×102 L·mol-1 for ADP-CB7] at 298 K with the same inclusive ratio of 1∶1.The main interaction forces between CB7] and the above purines were discussed based on the thermodynamic parameters.CB7] is only well water-soluble superamolecules among cucurbituril family members,and has great potential as drug carriers with safety and low toxicity.