Synthesis, characterization and applications of various metal carboxylates derived from N & S containing ligands

Abstract

Three new series of ligands (derived from amino acids) have been synthesized from view point of their structural and biological studies. The first series belongs to amide derivatives of amino acids (A1-A9), second belongs to urea derivatives of amino acids (A10-A18) and the third one belongs to thiourea derivatives of amino acids (A19-A30). Tributyltin(IV) and bismuth(III) derivatives of these ligands have also been prepared in good yields by refluxing the respective ligand with bismuth(III) chloride or tributyltin(IV) chloride in presence of potassium hydroxide in appropriate stoichiometric ratios in dry methanol as solvent. The structure of the synthesized compounds were characterized by elemental analysis, ICP-OES, FT-IR, multinuclear (1H, 13C, 119Sn) NMR spectroscopy and single crystal X-ray diffraction. Based on these results, the synthesis of ligands have been confirmed and the data also suggested that these ligands appeared to coordinate the bismuth and tin centers through the oxygen of carboxylate moiety. The tributyltin(IV) derivatives mostly demonstrate tetrahedral geometry both in solid and solution state. Whereas octahedral geometry was proposed for bismuth(III) complexes both in solid and solution state based on single crystal X-ray analysis, FT-IR and NMR spectroscopy respectively. Finally the biological activity tests such as anti-bacterial, anti-fungal, anti-oxidant, enzyme inhibition and lethality bioassays for majority of the synthesized ligands were carried out and found some encouraging results. All of the synthesized compounds were evaluated for their potential as anti-bacterial and anti-fungal agents against different strains of bacteria and fungi. Both of the tributyltin(IV) and bismuth(III) complexes have shown good to significant anti-bacterial and anti-fungal properties and some of them were found to be more potent than standard drugs available in markeet. It was observed that tributyltin(IV) complexes have shown slightly better activities than bismuth(III) complexes. These results propose that these compounds may be utilized as anti-bacterial and anti-fungal agents in future in the wake of following the medication improvement methodologies. Anti-oxidant potential of these newly synthesized compounds was also evaluated and some of them exhibited significant anti-oxidant activity. viii These compounds were also examined for their α-glucosidase inhibition, urease inhibition and lipoxygenase inhibition activity and some of the compounds showed excellent results in inhibiting these enzymes, even more than the standard drugs. Some compounds from all the series were tested for anti-tubercular activity and show poor activity. They were also assayed for their brine shrimp lethality test and data suggests that the compounds show low toxicity. However the data pertaining to bioassay tests for all the synthesized compounds exhibiting some encouraging results and may be trialed further in drug discovering processes to find out the lead compounds by modifying/altering their structural motifs.