Synthesis and crystal structure of manganese(III), zinc(II) and cadmium(II) complexes based on a symmetrical macroacyclic Schiff base ligand containing piperazine moiety, DNA binding studies of complexes

Abstract

Three macroacyclic Schiff base complexes have been obtained by the reaction of a previously known Schiff base ligand, 2-((Z)-(2-((4-((Z)-2-((Z)-2-hydroxy-3-methoxybenzylideneamino)benzyl)piperazin-1-yl)methyl)phenylimino)methyl)-6-methoxyphenol (H2L), and Mn(II), Zn(II) and Cd(II) ions in mixture of ethanol and methanol solvents. The resultant complexes were characterized by physical and spectroscopic methods. Molar conductivity (ɅM) data were measured at 25 °C using 10−3 M solutions of the complexes in acetonitrile solvent. In addition, the structure of the [MnL]ClO4·CH3CN complex has been revealed by a single-crystal X-ray structural analysis. In this complex, the Mn(II) has been oxidized to Mn(III), with the manganese ion being in a slightly distorted trans-O2N4 octahedral coordination environment arising from all six donor atoms of the doubly deprotonated ligand. The interaction of the ligand and the corresponding Mn(III), Zn(II) and Cd(II) complexes with calf thymus DNA (ct-DNA) has been appraised by dynamic viscosity, emission titration and competitive fluorescence methods which revealed that the compounds interact with ct-DNA via an intercalation mechanism.