A Study of the Behavior of alpha-Cyclodextrin with Single Solutions of Hydrogenated and Fluorinated Surfactants and Their Mixtures

作者：Xing Hang; Lin Shrong Shi; Xiao Jin Xin^*

来源：Journal of Chemical and Engineering Data, 2010, 55(5): 1940-1944.

DOI：10.1021/je900918e

The interactions between a-cyclodextrin (alpha-CD) and an equimolar mixture of the anionic hydrogenated and fluorinated surfactants sodium decyl sulfate (SDeS) and sodium perfluorooctanoate (SPFO), respectively, were studied by (1)H and (19)F NMR spectroscopy. It was directly proved that alpha-CD preferentially included the hydrogenated surfactant in such a surfactant mixture, although SDeS and SPFO showed almost the same hydrophobicity. The added alpha-CD formed 1:1 and 2:1 complexes with SDeS, but SPFO showed only a weak association with alpha-CD after the near saturation of inclusion of SDeS. Such selectivity of alpha-CD is contrary to that of beta-CD, as shown in our previous work in which beta-CD preferentially included the fluorinated surfactant in an SDeS/SPFO mixture. This selectivity of alpha-CD could be ascribed to the better fit between the cavity of alpha-CD and the hydrocarbon chain. It is consistent with the equilibrium constants (K) for the inclusion complexes in the solution. A peculiar trend of chemical shift variation was noted in mixtures of alpha-CD with the single surfactant SDeS: the chemical shift of beta-CH(2) increased rapidly while omega-CH(3) showed a smaller ascent to declivity, until both of them reached a plateau. The binding constant for the formation of the 2:1 alpha-CD/SDeS complex (K(2)) was found to be relatively large, as determined by the NMR investigation.

• 出版日期2010-5
• 单位北京大学