Binding ability of aminophosphonates containing imidazole and pyridine as additional donor systems

► We present solution studies of 2-imidazole ligands with Cu(II) and Ni(II) ions. ► The presence of 2-imidazole ring makes studied phosphonates very efficient ligands. ► pNi(II) of 2-imidazoles are few orders of magnitude higher than their 4(5)-analogs. ► Introduction of 2-pyridine as additional donor further increases the binding ability.