Synthesis and ion binding properties of A p-keto-oxime and a vic-dioxime derivative of calix[6]arene

A keto-oxime derivative of calix[6]arene was synthesized from 5,11,17,23,-29,35-hexaacetyl-37,38,39,40,41,42-hexamethoxycalix[6]arene by oxidation of the CH3 group of the acetyl groups to isonitroso groups. The prepared compound was converted into its vic-dioxime derivative by treatment with NH2OH.HCl. The resulting ligands (2, 3) were treated with three transition metal salts (e.g., CuCl2.2H2O, NiCl2.6H2O or CoCl2.6H2O) . While the Cu(II), Ni(II) and Co(II) complexes of the vic-dioxime derivative of calix[6]arene were obtained, only Co(II) gave a complex with the keto-oxime derivative of calix[6]arene. All the complexes have a metal-ligand ratio of 3:1. The Cu(II) and Ni(II) complexes of 3 are square-planar, while the Co(II) complex of both ligands are octahedral with water molecules as axial ligands.