Cr(II), Co(II) and Cu(II) complexes with 2-aminodiphenylamine derived Schiff base ligand: Synthesis, Characterization, DFT and Biological insights

Two Schiff bases viz. 2-(((2-(phenylamino)phenyl)imino)methyl)phenol (L1H) and 2-methoxy-6-(((2-(phenylamino)phenyl)imino)methyl)phenol (L2H) were synthesized by the reaction of 2-aminodiphenylamine with salicylaldehyde and o-vanillin in 1:1 molar ratio. A series of transition metal complexes of Cr(II), Co(II) and Cu(II) were synthesized using Schiff bases (L1H) and (L2H) in a 1:2 molar ratios. The newly synthesized ligands and metal complexes were characterized by elemental analysis and different spectroscopic techniques including FT-IR, UV–Vis, NMR and mass spectrometry. The DFT method was incorporated to get the electronic properties of ligands and their transition metal complexes. The spectroscopic analysis and computational method indicate distorted octahedral geometry around metal centers. The in vitro antimicrobial activities of synthesized ligands and transition metal complexes were evaluated against Escherichia coli and Staphylococcus aureus. The results indicate that metal complexes exhibit higher antibacterial activities as compared to free Schiff bases and lower as compared to the standard drug Gentamycin.