Synthesis, characterization, biological studies and DFT study of Schiff Bases and their complexes derived from aromatic diamine compounds with cobalt (II)

Abstract

Based on vanillin and diamine compounds (ortho phenylene diamine, meta phenylene diamine, 3,4- diamine toluene), derivation of two new Schiff base ligands (L1 and L2) was done, after which synthesis and treatment with Co (II) chloride was performed at a metal-to-ligand ratio of 1:1 to get two new complexes, i.e. [CoL3(H2O)2]Cl2 and [CoL1(H2O)2]Cl2. These complexes and ligands were characterized by employing NMR, IR, atomic absorption, UV visible absorption, molecular weight determination, molar conductance, and magnetic measurement techniques. As per the data, the ligands were found to be bidentate ligands that were linked to two azomethine nitrogen sites. It was suggested that these complexes were paramagnetic electrolyte compounds that possessed coordination number four. Screening of the ligands and metal complexes was done to assess their antimicrobial activities against gram-negative and gram-positive bacteria, which was found to show biological activity. Calculations using quantum chemistry were done to examine the molecule geometry. The investigation includes several quantum chemical characteristics derived from frontier molecular orbitals. Keywords: Schiff bases, transition metal complexes, vanillin, diamine aromatic compounds, antibacterial activity, DFT study.