Studies on mixed-ligand complexes of some transition metals of biological interest

Abstract

A series of mixed-ligand complexes of Co(II), Ni(II), Cu(II) and Zn(II) with general formulaM(IM)(L)·H2O, where H2IM=iminodiacetic acid;L=2,2′-bipyridyl ando-phenanthroline, have been studied and isolated in pure state. The metal chelates have been characterized by elemental analysis, IR and electronic spectra, conductivity and magnetic measurements. The octahedral environment around the metal ion has been proposed. The thermal properties of metal complexes in solid state have been studied under non-isothermal condition in nitrogen atmosphere by simultaneous TG and DTA. TG and DTA curves show that the decomposition took place in two steps. Thermodynamic parameters such as activation energy,E, order of reaction,n, entropy of activation, ΔS‡, and free energy of activation, ΔG‡, have been determined by standard methods. All the complexes are non-electrolytic in nature. The antimicrobial activity against fungi is critically examined. The difference in their site of action against various fungi has been explained on the basis of formation constants and liposolubility.