Metal complexes as antibacterial agents: Synthesis, characterization and antibacterial activity of some 3d metal complexes of sulphadimidine

Abstract

Metal complexes of Sulphadimidine(SAD) were synthesized.The complexes were formulated as [Co(SAD) 2 Cl 2 ], [Cu(SAD) 2 (H 2 O) 2 ], [Ni (SAD) 2 Cl 2 H 2 O], [Cd (SAD) 2 Br 2 ], [Fe (SAD) 3 ](H­ 2 O)­ 3 and [Mn (SAD) 2 Cl 2 ] characterized by elemental Analysis, conductivity, IR , UV-Vis, Magnet moment and 1 H-NMR and Mass spectroscopies. Co(II), Mn (II), and Ni(II) sulphadimidine complexes consist of metal ion which coordinates through amino nitrogen of the terminal NH 2 group and oxygen of sulfonamidic group of the two molecules of sulphadimidine ligand and two halide ions to form octahedral structure while Cd(II) coordinates with sulphadimidine through amino nitrogen of the terminal NH 2 group with two bromine ions to complete tetrahedral structure. In Cu(II) sulphadimidine complex, copper ion coordinates through both pyrimidinic nitrogen (heterocyclic nitrogen) and sulfonamidic nitrogen of the two molecules of sulphadimidine. Fe(III) coordinates to three molecules of sulphadimidine through heterocyclic nitrogen (pyrimidinic nitrogen) and sulfonamidic nitrogen,with three molecules of water outside the coordination sphere. Both Fe(III) and Cu(II) complexes exhibit octahedral geometry. The antibacterial activity of the complexes and the ligands was investigated against Esherichia coli , Staphylococcus aureus and Klebsiella pneumonia . The data obtained revealed that the complexes showed greater activity against the three micro-organisms when compared to parent compound. Stability constant of the complexes were evaluated for the metal salts, the order of stability constant b was found to be Cu (II) > Fe (III) >Ni(II)> Co (II) > Cd (II).The values of stability constant ( b ) was found to be log 6.31, 5.93, 5.29, 4.63 and 3.92, respectively. The stability constant data revealed that this ligand may be used as antidote or chelating agent for medical treatment of metals overload or poisoning.