Self-assembling supramolecular columnar organogels formed by wedge shaped cesium 3,4,5-alkyloxy benzene sulfonates

Abstract

A systematic investigation of the homologous series of cesium 3,4,5-tris(alkoxy) benzenesulfonates with different alkyl lengths was conducted to assess their capacity for low molecular weight organogels formation by self-assembling of fibrillar networks. Such goal was achieved through both spontaneous and quench gelation techniques at temperatures of +20 °C, −5 °C, and −20 °C across thirteen different organic solvents. The morphologies of representative gel samples, were monitored using electron microscopy. This analysis revealed the presence of cylindrical elementary fibrils approximately 5 nm in diameter, with sulfonate groups oriented to the axis of the cylinders. Furthermore, the formation of gel netpoints appears to be predominantly facilitated by local branching within fiber bundles. Wedge-shaped dendrons derived from benzenesulfonic acid exhibit a remarkable diversity of phase behavior, attributable to the potential for molecular shape modulation through incremental alterations in their chemical structure. Specifically, variations in the length of aliphatic tails, extending from 14 to 18 methylene units, induce significant transformations in phase behavior. At ambient temperature, these compounds manifest columnar ordered oblique phases in the bulk state. Upon heating they undergo transformation into columnar hexagonal disordered phases and to a cubic BCC phase. General gel structure–property relationships were established and discussed.