Synthesis, characterization and redox properties of macrocyclic Schiff base by reaction of 2,6-diaminopyridine and 1,3-bis(2-carboxyaldehyde phenoxy) propane and its CuII, NiII, PbII, CoIII and LaIII complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:, 14,15-tribenzo-9,13-dioxacyclohexadeca-1,5-diene ( L) was synthesized by reaction of 2,6-diaminopyridine and 1,3-bis(2-carboxyaldehyde phenoxy) propane. Then, its Cu-II, Ni-II, Pb-II, Co-III and La-III complexes were synthesized by a template effect by reaction of 2,6-diaminopyridine and 1,3-bis (2-carboxyaldehyde phenoxy) propane and Cu(NO3)(2) center dot 3H(2)O, Ni(NO3)(2) center dot 6H(2)O, Co(NO3)(2) center dot 6H(2)O, La(NO3)(3) center dot 6H(2)O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, H-1- and C-13-NMR-, UV-vis spectra, magnetic susceptibility, conductivity measurements, mass spectra and cyclic voltammetry. All complexes are diamagnetic and the Cu-II complex is binuclear. The diamagnetic behaviour of the binuclear complex may be explained by a very strong anti-ferromagnetic interaction in the Cu-Cu pair. The Co-II was oxidised to Co-III.