Synthesis and characterization of a new macrocyclic Schiff base derived from 2,6-diaminopyridine and 1,10-bis(2-formylphenyl)-1,4,7,10-tetraoxadecane and its Cu(II), Ni(II), Pb(II), Co(III) and La(III) complexes

A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:19,20-tribenzo-9,12,15,18-tetraoxacyclounkosa-1,5-diene (L) was synthesized by reaction of 2,6-diaminopyridine and 1,10-bis(2-formylphenyl)-1,4,7,10-tetraoxadecane. Then, its Cu-II, Ni-II, Pb-II, Co-III and La-III complexes were synthesized by the template effect by reaction of 2,6-diaminopyridine and 1,10-bis(2-formylphenyl)-1,4,7,10-tetraoxadecane and Cu(NO3)(2)center dot 3H(2)O, Ni(NO3)(2)center dot 6H(2)O, Pb(NO3)(2), 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, u.v-vis spectra, magnetic susceptibility, conductivity measurements and mass spectra. All complexes are diamagnetic and the Cu-II complex is binuclear. The Co-III complex was oxidized to Co-III.