Synthesis, characterization, and electrochemical study of two new macroacyclic Schiff bases and their copper(II) and zinc(II) complexes

Abstract

Two new potentially octadentate N2O6 Schiff-base ligands 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy) phenoxy)phenylimino)methyl)-6-methoxyphenol H2L1 and 2-((E)-(2-(2-(2-((E)-2-hydroxy-3-methoxybenzylideneamino)phenoxy) -4-tert-butylphenoxy)phenylimino)methyl)-6-methoxyphenol H2L 2 were prepared from the reaction of O-Vaniline with 1,2-bis(2'-aminophenoxy)benzene or 1,2-bis(2'-aminophenoxy)-4-t-butylbenzene, respectively. Reactions of H2L1 and H2L 2 with copper(II) and zinc(II) salts in methanol in the presence of N(Et)3 gave neutral [CuL1] 0.5CH2Cl2, [CuL2], [ZnL1] 0.5CH2Cl2, and [ZnL2] complexes. The complexes were characterized by IR spectra, elemental analysis, magnetic susceptibility, ESI-MS spectra, molar conductance (m), UV-Vis spectra and, in the case of [ZnL1] 0.5CH2Cl2 and [ZnL2], with 1H- and 13C-NMR. The crystal structure of [ZnL1] 0.5CH2Cl2 has also been determined showing the metal ion in a highly distorted trigonal bipyramidal geometry. The electrochemical behavior of H2L2 and its Cu(II) complex, [CuL2], was studied and the formation constant of [CuL2] was evaluated using cyclic voltammetry. The logarithm value of formation constant of [CuL 2] is 21.9. © 2010 Taylor & Francis.