Nagarjuna Chapireddy, Ramakanth Illa
Department of Chemistry, School of Advanced Sciences, VIT-AP University, Amaravati, Andhra Pradesh 522241, India.
R Soc Open Sci. 2025 Mar 5;12(3):241398. doi: 10.1098/rsos.241398. eCollection 2025 Mar.
A charge transfer gel from a cetyltrimethylammonium bromide (CTAB) and an additive 6-aminocaproic acid (6-ACA), in a two-component solvent mixture at a critical solvent composition of 3 : 1 v/v water : toluene is reported. The pale yellow colour of the gel arising from charge transfer interactions between the amine group (-NH) of hexylamine and the ammonium ion (N) of CTAB was confirmed after performing a set of trial experiments with CTAB-heptanoic acid and CTAB-hexylamine systems. The process of gelation, gel phase development and its microstructure were investigated using spectroscopy, microscopy, and small-angle X-ray scattering (SAXS) techniques. The gel formed a lamellar organization while preserving a loose-packed arrangement of a bilayer of CTAB and 6-ACA molecules, maintaining H-bonding along with significant charge transfer interactions. The SAXS pattern revealed a distinct crystalline form of the lamellar gel, indicating a stable phase characterized by alternating layers of crystalline and amorphous structures. This unique gelation nature was inferred from the interplanar spacings, demonstrating its non-conducive properties in highly polar solvents such as methanol and ethanol, as well as in less polar solvents like cyclohexane and carbon tetrachloride, when the organic solvent polarity was altered in the presence of water in the mixed amphiphilic system.
据报道，在水与甲苯体积比为3:1的临界溶剂组成的二元溶剂混合物中，由十六烷基三甲基溴化铵（CTAB）和添加剂6-氨基己酸（6-ACA）形成了一种电荷转移凝胶。在用CTAB-庚酸和CTAB-己胺体系进行了一系列试验后，证实了凝胶的浅黄色是由己胺的胺基（-NH）与CTAB的铵离子（N）之间的电荷转移相互作用引起的。使用光谱学、显微镜和小角X射线散射（SAXS）技术研究了凝胶化过程、凝胶相发展及其微观结构。该凝胶形成了层状结构，同时保持了CTAB和6-ACA分子双层的疏松堆积排列，维持了氢键以及显著的电荷转移相互作用。SAXS图谱揭示了层状凝胶的一种独特晶型，表明其为一种稳定相，其特征是具有交替的结晶和无定形结构层。这种独特的凝胶化性质是从晶面间距推断出来的，表明在混合两亲体系中存在水的情况下，当有机溶剂极性改变时，它在甲醇和乙醇等高极性溶剂以及环己烷和四氯化碳等低极性溶剂中均具有非导电特性。
