Biological Potential of Homo- and Heteronuclear Complexes of Iminodiacetic Acid

Background: Natural ligands containing the carboxylate group have been broadly utilized in many coordination complexes because of their simple manufacturing strategies, magnificent chelation properties, and biological potential. The carboxylate ligands may bind to the metal atoms in a variety of coordination modes which include monodentate/bidentate/chelating modes and may result in the formation of homo- and heterobimetallic complexes. Objective: Current research is focused on synthesis, characterization, antibacterial and anti-inflammatory studies of homo- and heteronuclear complexes with iminodiacetic acid (NA2L). Methodology: Four homo-bimetallic Me3SnLSnPh3 (1), Me3SnLSn(Cl)Ph2 (2), Ph3SnLSn(Cl)Me2 (3) and Bu3SnLSn(Cl)Me2 (4) products having different organotin moieties were successfully synthesized by refluxing NA2L in toluene firstly with Me3SnCl/Bu3SnCl/Ph3SnCl and then with Ph3SnCl/Ph2SnCl2/Me2SnCl2. Refluxing NA2L with tributyltin(IV) chloride in 1:2 molar ratio for 3 hours and subsequent reaction with equimolar MCl2 produced the heterobimetallic products of the general formula Bu3SnLMLSnBu3 where M (a transition metal) = Zn, Cu, Mn and Cd for compounds 5-8, respectively. The products were characterized by elemental analysis (CHN), FTIR, and 1HNMR spectroscopy. Results: The carboxylate donor sites of NA2L ligand act with organotin(IV) moieties in an iso-bidentate fashion. In solid state, the central tin atom exhibits a trigonal bipyramidal configuration and hetero metal atoms (Zn, Cu, Mn, Cd) has square planer geometry. 1H NMR spectroscopy verified the ligand-metal coordination. The coordination products 2 and 5 have shown the highest biofilm inhibitions against Escherichia coli and Staphylococcus aureus, respectively. Complex 3 is inactive against both strains of bacteria. The anti-inflammatory activities of the synthesized products were lowered in the following descending order: 3>4>1>2>5. Conclusion: We have successfully synthesized four homo-binuclear complexes i.e., Me3SnLSnPh3 (1), Me3SnLSn(Cl)Ph2 (2), Ph3SnLSn(Cl)Me2 (3) and Bu3SnLSn(Cl)Me2 (4) and four heterobimetallic products of the general formula Bu3SnLMLSnBu3 where M = Zn, Cu, Mn and Cd for compounds 5-8, respectively. Their structural features were verified by elemental analysis, FTIR, and 1HNMR spectroscopy. They have generally shown good antibacterial and anti-inflammatory potential.