Structural and Microbial Studies of some Transition Metal Complexes of 7-Substituted-8-Hydroxyquinoline-5-Sulphonic Acid Ligands

Abstract

The reaction of 7-substituted derivatives of the ligand 5-sulpho-8-hydroxyquinoline (7-X-HL), (X=H, NH 2 , NO 2 and I), with some biologically important transition metal ion such as {Cr(III), Fe(III), Mn(II), Fe(II), Co(II), Ni(II), and Cu(II)} was investigated. The formation of ML n (n=1, 2) complexes of the ligand Na[7-I-HL] has been established by conductometric titrations in 10% (v/v) ethanol-water. The complexes of the ligands with all of the above transition metal ions which have been synthesized were characterized by elemental analyses, molecular weight determinations, X-ray diffraction (XRD), magnetic moments (µ eff ), and thermal analyses (DTA and TG). The data suggest the composition of these complexes, which have an octahedral coordination. The general formula is Na 2 [ML 2 (H 2 O) 2 ]·4H 2 O where M(II)=Mn, Fe, Co, Ni and Cu. The thermal analyses of the complexes show that for Na 3 [ML 3 ]·6H 2 O where M(III)=Cr and Fe all water molecules are lattice water. The antibacterial activity of these ligands and their divalent transition metal complexes has been determined on gram-positive ( Sarcina lutea ) and gram-negative ( Escherichia coli ) bacteria at 37°C, and antifungal activity has been determined on common fungi viz . ( Aspergillus niger , and Candida albicans ) at 30°C. A considerable increase in the biocidal activity of these ligands on being coordinated with transition metal ions has been reported. These compounds can be recommended to use for the chemotherapy of candidiaces and other fungal skin diseases.