Thermal behavior of novel catanionic cholates

Abstract

In this article, we bring new insight into room temperature structure of catanionic cholates and complement their thermal behavior given by the conventional thermal techniques with the XRPD technique. The comparative study of the addition of each dodecyl chain and ammonium group is made bearing in mind the complete architecture of synthesized cholates. The examined samples are crystal smectic phases at room temperature, with proposed sandwich-type structure, promoted by cholates architecture. For most of the studied compounds, thermal behavior is characterized as formation of structural varieties and/or polymorphs as low-temperature phases and formation of high-temperature mesomorphic, lamellae-like phases. The exception is dimeric dicholate, which only forms SmA phase before its decomposition. The dependence of the isotropization temperatures, enthalpy and entropy changes, on the increasing ammonium headgroup number, points to the fact that thermal stability of these catanionics depends on the structure of cationic component that is its constituent, where cholate anion shows minor effect. The chemistry of amphiphiles, their supramolecular behavior and thermotropic affinity is at the frontier of the contemporary research and design of the new functional materials, because this is simple but effective way to control the nature and location of reactions. From that point of view, the systematic analysis of physico-chemical properties of various catanionic amphiphiles brings new findings of their chemical structure–properties relationship, therefore enabling simpler and reliable way of new materials synthesis with desired properties.