Ni(II) complex of (3,3-dimethyl-7-oxo-6-(2-Phenylacetamido)-4-thia1-Azabicyclo[3.2.0]heptane-2-carboxylic acid : Synthesis, characterization and antibacterial activities

Abstract

The ligand (3,3-Dimethyl-7-oxo- 6-(2-phenylacetamido)-4-thia-1-azabicyclo[3.2.0-] heptane-2-carboxylic acid (DPTA) is a β-lactamin derivative used in the treatment of infections caused by gram-positive bacterial strains and few gramnegative bacterial strains.[Ni(DPTA)] was synthesized by the reaction of DPTA with NiCl2.6H2O. Physical properties such as solubility, colour and melting point were determined for the ligand, DPTA and the synthesized complex, [Ni(DPTA)]. The complex is found to be light green in colour. The ligand and the complex are ionic in nature with molar conductivity values of 218.2 and 126.0 Sm2mol-1 respectively. The complex was characterized based on elemental analysis, UVVisible, infrared, 1H NMR and 13C NMR spectroscopy. Spectroscopic data suggested that the DPTA coordinated to Ni ion through OH, C=O of amide, C=O of carboxylic acid, C=O of β-lactam and NH functional groups. Also since DPTA was coordinated to nickel centre through five sites it was also proposed that it acted as a pentadentate ligand around the nickel centre. The antibacterial studies of the ligand and its nickel complex were carried out against four-gram negative bacterial strains (Escherichia coli, Enterobacter cloacae, Pneumonia aeruginosa and Campylobacter fetus) and four-gram positive bacterial strains (Staphylococcus aureus, Bacillus substilis, Bacillus cerus and Enterococcus faecalis). The results  showed that [Ni(DPTA)] exhibited better antibacterial activity than DPTA. Its study concluded that the process of chelation affected the biological behavior of the compound which in turn increase the inhibitory potential against the bacterial strains.