Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, CdMx 04510, Mexico; Department of Physical Chemistry, University of Chemistry and Technology, Technická 5, 166 28 Prague 6, Czech Republic.
Laboratorio de Biofisicoquímica, Departamento de Fisicoquímica, Facultad de Química, Universidad Nacional Autónoma de México, CdMx 04510, Mexico.
J Colloid Interface Sci. 2017 Nov 1;505:445-453. doi: 10.1016/j.jcis.2017.05.093. Epub 2017 Jun 8.
The interaction of α-cyclodextrin (α-CD) with ten ionic surfactants (S) in water was systematically examined using isothermal titration calorimetry. The S comprised cationic and anionic head groups while the hydrocarbon alkyl chain length varied from eight to fourteen carbon atoms. The heat data were measured at five temperatures ranging from 283.15K to 318.15K and were treated simultaneously allowing the estimation of a thermodynamically consistent temperature dependence of the equilibrium constant, as well as the enthalpy and heat capacity for the sequential formation of the [α-CD·S] and the [α-CD·S] inclusion complexes. All attempts to fit the data assuming that only [α-CD·S] complexes are present failed. It was found that the thermodynamic footprint of the [α-CD·S] complexes does not depend importantly on the head group, while the formation and stabilization of the [α-CD·S] complexes is strongly influenced by the chemical nature of the polar head group. Several contributions to the thermodynamic parameters are discussed in detail. Among the studied surfactants, the decyl- and octylsulfates were identified as those with a predominant content of [α-CD·S] complexes and hence they are promising candidates to form viscoelastic films at the liquid/air interface, as it was found previously for the dodecylsulfate surfactant.
利用等温滴定量热法系统地研究了α-环糊精（α-CD）与十种离子表面活性剂（S）在水中的相互作用。S 包含阳离子和阴离子头基，而烃链长度从八个到十四个碳原子不等。在 283.15K 到 318.15K 的五个温度下测量了热数据，并同时进行了处理，从而可以估计平衡常数的热力学一致的温度依赖性，以及顺序形成[α-CD·S]和[α-CD·S]包络复合物的焓和热容。所有试图拟合数据的尝试都假设仅存在[α-CD·S]复合物，但都失败了。结果发现，[α-CD·S]复合物的热力学特征并不重要地取决于头基，而[α-CD·S]复合物的形成和稳定则强烈受到极性头基的化学性质的影响。详细讨论了热力学参数的几个贡献。在所研究的表面活性剂中，癸基硫酸盐和辛基硫酸盐被确定为具有主要含量的[α-CD·S]复合物的表面活性剂，因此它们是在液体/空气界面形成粘弹性膜的有前途的候选物，正如先前对十二烷基硫酸盐表面活性剂的研究结果。
