Geminal imidazolium salts: a new class of gelators

Ionic Liquids (ILs) are organic salts characterized by a low melting point (less than 100 °C), high thermal stability and high structural order in the liquid state. ILs, when used as solvents, are able to influence the outcome of some organic reactions. In the last few years, some new generation Ionic Liquids have attracted the attention of researchers. These salts are defined Geminal Ionic Liquids and are characterized by the presence of two cationic moieties on the same molecule. Geminal ILs present a higher thermal stability than monocationic ones. Their properties depend, not only on the nature of the ions, but also on the structure of the linker.1 Under this light, we decided to synthesise Geminal Ionic Liquids that had small differences in their molecular structure. In particular we studied 3,3’-di-n-octil-1,1’-(1,3-phenylenedimethylene)diimidazolium 1,5-naphtalendisulfonate, 3,3’-di-n-octil-1,1’-(1,3-phenylenedimethylene)diimidazolium 2,6-naphtalendisulfonate, 3,3’-di-n-octil-1,1’-(1,4-phenylenedimethylene)diimidazolium 1,5-naphtalendisulfonate, 3,3’-di-n-octil-1,1’-(1,4-phenylenedimethylene)diimidazolium 2,6-naphtalendisulfonate. Thanks to the network of interactions acting in their structure, they are able to form Organogels when dissolved in some alcohols. With the aim to evaluate the stability of formed gels, we determined the Tgel at different composition of the mixture.In a gel phase the understanding of tridimensional organization of gelator molecules is a very important feature. For this reason we decided to study the gelation mechanism using Resonance Light Scattering spectroscopy.