Mn(II), Co(II), Ni(II), and Cu(II) complexes of amino acid derived Schiff base ligand: Synthesis, characterization and in-vitro antibacterial investigations

A O Rajee,A A Aliyu,J A Obaleye,A O Sheriff,W A Osunniran,M Lawal,A Lawal,H F Babamale

doi:10.4314/bcse.v35i1.8

Abstract

Four complexes of Mn(II), Co(II), Ni(II) and Cu(II) with Schiff base ligand (H3L) derived from 2-amino-3-methylbutanoic acid and acetylacetonate were synthesized. All complexes were characterized by elemental analysis, Fourier-transform infrared spectroscopy and electronic spectroscopy. The results confirmed the coordination of the ligand to metals in tridentate fashion via the hydroxyl oxygen, the azomethine nitrogen and the enolic acetylacetonate oxygen. Antimicrobial activities were established for all complexes, free ligand and ciprofloxacin for comparison. Both the ligand and its metal complexes were active against Gram-positive and negative bacterial strains. The Cu(II) complex, showed highest antibacterial activity among the complexes screened. Other complexes displayed considerable antibacterial activity. Octahedral geometry was proposed for the metal(II) complexes with the Schiff base.  KEY WORDS: Schiff base, Amino acid, Metal Complexes, Antibacterial agents  Bull. Chem. Soc. Ethiop. 2021, 35(1), 97-106. DOI: https://dx.doi.org/10.4314/bcse.v35i1.8

Highlights

Microbial resistance to antibiotics has become an issue of worldwide concern, which requires concerted efforts to address it [1, 2]
The Schiff base behaves as a tridentate as the results indicates, coordinating to the central metals through the enol form of the acac oxygen, azomethine nitrogen and carboxylate oxygen (Figure 2)
The disc diffusion method was employed in screening the antibacterial potential of the Schiff base and metal complexes against clinical isolates of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniea

Summary

Introduction

The Schiff base ligand (H3L) was prepared by condensation of 2-amino-3-methylbutanoic acid (0.06 mmol) with acetylacetonate (0.06 mmol) in 20 mL of H2O/ethanol and the mixture was stirred for 4-5 h. Mn(II), Co(II), Ni(II), and Cu(II) complexes of amino acid derived Schiff base ligand 99 A new series of Schiff base complexes, [M(H3L)(H2O)Cl2], (Mn(II), Ni(II), Co(II) and Cu(II)) have been derived from the reaction of 2-amino-3-methylbutanoic acid and acetylacetonate in presence of respective metal salts.

Results

Conclusion