Interactions between β-cyclodextrin and an amino acid-based anionic gemini surfactant derived from cysteine
Interactions between β-cyclodextrin and an amino acid-based anionic gemini surfactant derived from cysteine
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DOI：
10.1016/j.jcis.2011.07.101
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发表时间：
2012-02-01
影响因子：
9.9
通讯作者：
Garcia-Rio, Luis
中科院分区：
文献类型：
--
作者：
Faustino, Celia M. C.;Calado, Antonio R. T.;Garcia-Rio, Luis
采用电导法、以酚酞为探针的紫外-可见光谱置换法和核磁共振氢谱法研究了β-环糊精（β-CD）与半胱氨酸（C（8）Cys）2衍生的双子表面活性剂的相互作用.所获得的数据表明，β-CD和所研究的双子表面活性剂之间形成1：1的包合复合物，并考虑到该化学计量，允许测定结合常数K-1。电导率，光谱位移技术，和NMR化学位移测量，获得的含水β-CD-表面活性剂系统，产生一致的K-1值在10（2）dm（3）mol（-1）的顺序，典型的弱结合β-CD-表面活性剂复合物。还研究了包合物的存在对双子表面活性剂胶团化过程的影响，得到了表观临界胶团浓度（cmc*）。发现增加β-CD浓度使cmc* 向更高的值移动，因为络合的表面活性剂单体不能形成胶束，并且仅当所有β-CD空腔被占据时才发生聚集。(C)2011 Elsevier Inc. All rights reserved.
The interaction between beta-cyclodextrin (beta-CD) and an amino acid-based anionic gemini surfactant derived from cysteine (C(8)Cys)2 was studied by three independent techniques: electrical conductivity, UV-Vis spectral displacement technique using phenolphthalein as probe, and H-1 NMR spectroscopy. The data obtained indicated the formation of a 1:1 inclusion complex between beta-CD and the gemini surfactant studied and allowed for the determination of the binding constant, K-1, by considering this stoichiometry. Electrical conductivity, spectral displacement technique, and NMR chemical shift measurements, obtained for aqueous beta-CD-surfactant systems, yielded consistent K-1 values in the order of 10(2) dm(3) mol(-1), typical of a weakly bound beta-CD-surfactant complex. The influence of the presence of the inclusion complex on the micellization process of the gemini surfactant has also been studied and the apparent critical micelle concentration (cmc*) has been obtained. Increasing beta-CD concentration was found to shift the cmc* to higher values, as complexed surfactant monomers are not available to form micelles and aggregation takes place only when all beta-CD cavities are occupied. (C) 2011 Elsevier Inc. All rights reserved.