STUDIES OF THE EFFECT OF TRANSITION METAL ION ON THE BIOLOGICAL ACTIVITY OF SOME NOVEL ORGANIC COMPOUNDS

Abstract

This project was aimed at the synthesis of some chromone derived ligands and their transition metal complexes of biological significance. The ligands 1–17 were synthesized by the reactions of 6,8-dichloro-3-formylchromone and 4-aminobenzoic hydrazide, 4-brmobenzoic hydrazide 4- chlorobenzoic hydrazide, , 4-hydroxybenzoic hydrazide, isonicotinic hydrazide, nicotinic hydrazide, 2,5-dichlorophenylhydrazine, tetraflororophenylhydrazine, 2,5-diflororophenylhydrazine, m-tolylhydrazine hydrochloride, 2,3,5,6- 4-methoxyphenylhydrazine hydrochloride and 4-hydrazinobenzoic acid, semicabazide, 4-phenylsemicarbazide, 4,4- diphenylsemicarbazide, thiosemicarbazide and 4-phenylthiosemicarbazide respectively. The structures of all the ligands were determined by analytical and spectral (IR, 1H-NMR) techniques. These ligands 1–17 were used for synthesizing their copper (II) complexes 18 – 34. All the synthesized metal complexes were characterized by elemental analyses, molar conductance, magnetic moment, IR, electronic spectral and thermal data and were found to be six-coordinated exhibiting octahedral geomatry. The synthesized ligands and their transition metal complexes were screened for their in vitro antibacterial activity against four Gram-negative (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Shigella flexneri) and two Gram-positive (Bacillus subtilis, Staphylococcus aureus) bacterial strains by the agar-well diffusion method. The ligands were found to exhibit either no or low to moderate activity against one or more of the bacterial species. Whereas, all the metal complexes exhibited varied activity against different bacteria. The ligands, which were inactive before complexation became active and less active ones became more active upon coordination with copper ions. The complexes 18 - 22, 27 - 28 and 30 - 33 showed comparatively much higher activity. However, the metal complex 34 was found to be the most active one.