AGGREGATION BEHAVIOR AND COPPER-BINDING PROPERTIES OF SURFACTANTS CONTAINING IMIDAZOLE AND PYRAZOLE LIGANDS

The synthesis and aggregation behaviour of simple dialkylamine-imidazo le and dialkylamine-pyrazole surfactants is described. In the presence of one equivalent of HCI the imidazole surfactants form stable vesicu lar dispersions. Addition of copper(II) dichloride to these dispersion s leads to formation of metallo-vesicles in which four imidazole group s are coordinated to one copper(II) ion. These metallo-vesicles are un stable and are slowly converted into stacked bilayers, which precipita te. The pyrazole surfactants on the other hand do not form vesicles bu t give, with one molar equivalent of HCl, water-insoluble stacked bila yers. The pyrazole moieties in these stacked bilayers do not coordinat e copper(II) ions. This behaviour is most probably due to the formatio n of an intramolecular hydrogen bond in the mono-protonated pyrazole s urfactant molecule. The imidazole surfactants cannot form such a hydro gen bond.