Di- and Tricationic Organic Salts: An Overview of Their Properties and Applications

During recent years growing interest has been devoted to the synthesis and applications of polycationic organic salts. Among them, di- and tricationic organic salts can be considered the natural evolution of monocationic ones. These last have given rise to the large class of ionic liquids. In the cases of di- and tricationic organic salts, the potential to change their structural features simply by varying the properties either of the charged heads or of the spacers separating them provides the opportunity to obtain materials suitable for different applications. This review article highlights recent progress in the study of the properties of di- and tricationic organic salts, as well as in some of their uses as solvent systems, receptors for anion recognition, ionic liquid crystals, low-molecular-weight gelators, additives for dye-sensitized solar cells, and so on.