Aggregation behaviour and copper‐binding properties of surfactants containing imidazole and pyrazole ligands

Abstract

AbstractThe synthesis and aggregation behaviour of simple dialkylamine‐imidazole and dialkylamine‐pyrazole surfactants is described. In the presence of one equivalent of HCl the imidazole surfactants form stable vesicular dispersions. Addition of copper(II) dichloride to these dispersions leads to formation of metallo‐vesicles in which four imidazole groups are coordinated to one copper(II) ion. These metallo‐vesicles are unstable and are slowly converted into stacked bilayers, which precipitate. The pyrazole surfactants on the other hand do not form vesicles but give, with one molar equivalent of HCl, water‐insoluble stacked bilayers. The pyrazole moieties in these stacked bilayers do not coordinate copper(II) ions. This behaviour is most probably due to the formation of an intramolecular hydrogen bond in the mono‐protonated pyrazole surfactant molecule. The imidazole surfactants cannot form such a hydrogen bond.