期刊
JOURNAL OF MOLECULAR LIQUIDS
卷 145, 期 3, 页码 197-203出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.molliq.2008.02.009
关键词
Calixarenes; Aqueous solutions; Micelles; Acid-base indicators; Surfactants
Water-soluble ionic calixarenes belong to very promising macrocyclic molecules owing to their applications in biochemistry. However, the state of such substances in aqueous media is still unclear. The present paper is devoted to gaining insight into the properties of aqueous solutions of a cationic calixarene, 5,11,17,23-tetra(N, N-dimethyl-N-hydroxyethylammonium)-methylene-25,2 6,27,28-tetrapropoxycalix[4]arene tetrachloride, within a wide concentration range. For this purpose. we examined the influence of the above system on the equilibrium of sixteen acid-base indicator dyes, with various charge types of acid-base couples, by means of vis-spectroscopy. The deviations of the 'apparent' ionization constants, K-a(a), from the values in pure water, K-a(w), and the shifts of the absorption bands of the dyes were compared with those in micellar solutions of common cationic surfactants. This confrontation, as well as dynamic light scattering measurements, confirms the existence of small positively charged aggregates. Several experiments were made with anionic and nonionic water-soluble calixarenes. The performed study allows to make three conclusions about ionic calixarenes (i) in aqueous media, they form micelle-like aggregates, (ii) such aggregates are able to strongly modify protolytic properties of other dissolved substances and (iii) the calixarene+dye associations are governed rather by electrostatic and hydrophobic interactions, than by expected 'Hosts-Guest' ones. (C) 2008 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据