New Schiff base ligand and some of its coordination compounds: Synthesis, spectral, molecular modeling and biological studies

Abstract

Schiff bases are important compounds due to their various applications, especially from the biological point of view. A series of metal complexes derived from the 2-((4-oxopentan-2-ylidene)amino)benzoic acid (H2L) with Co(II), Zn(II), Cu(II) and Ni(II) were isolated and characterized. The elemental, mass and thermal analyses confirmed the suggested 1:1 (M:L) stoichiometric. The IR and 1H NMR spectra indicated that the new Schiff's base ligand coordinated to the metal ion as binegative tridentate chelator through azomethine nitrogen along with the deprotonated carboxylate and enolized carbonyl oxygen atoms. The DFT calculations of frontier molecular orbitals for the synthesized compounds were carried out and their HOMO-LUMO energy gap (ΔEH-L) displayed good agreement with the experimentally determined optical band gap (Eg). Furthermore, the antimicrobic activity of the isolated compounds against four microorganism, Staphylococcus aureus, Vibrio cholerae, Aspergillus Niger and Aspergillus flavus were screened and indicated that the Ni(II) and Zn(II) complexes were the most active.