Spectral, magnetic, thermal, antioxidant and biological studies on new mixed ligand complexes

Abstract

In this study, new mixed ligand complexes have been synthesized from bis(2,4,4-trimethylpentyl)dithiophosphinic acid (C16H35PS2) and 1,10-phenanthroline (C12H8N2) with various metal(II) ions. The molecular formula of the metal complexes were [Mn(C16H34PS2)(C12H8N2)] (1), [Fe(C16H34PS2)(C12H8N2)] (2), [Ni(C16H34PS2)(C12H8N2)] (3), [Zn(C16H34PS2)(C12H8N2)] (4) and [Cd(C16H34PS2)(C12H8N2)] (5). These complexes have been characterized by various physico-chemical techniques such as melting point, molar conductance, magnetic susceptibility measurements as well as UV–vis, IR, TG and mass spectroscopic analyses. The surface morphology was determined by scanning electron microscope (SEM). The magnetic moment value, color as well as spectral measurements suggested that the geometrical structures of the metal complexes were tetrahedral. The spectral data showed that bis(2,4,4-trimethylpentyl)dithiophosphinic acid and 1,10-phenanthroline ligands acted as uninegative and neutral bidentate ligand, respectively. They also coordinated with metal(II) ion through two sulfur and two nitrogen atoms. The obtained mixed ligand complexes were more stable in air and highly soluble in common organic solvent. The bio-efficacy of ligands and metal complexes have been screened against the test microorganism using agar disc diffusion method. The biological activity results of metal complexes showed that complex 4 displayed potential antibacterial activity against Clostridium botulinum as compared to the standard drug, imipenem. The complex 2 and 4 were found to have better scavenging activity against 2,2-diphenyl-1-picrylhydrazyl.