Synthesis, spectroscopic characterization, crystal structure and Hirshfeld surface analysis of Co(III), Ni(II) and VO(IV) metal complexes with a novel Schiff base ligand and their antimicrobial activities

A new series of transition metal complexes of Co(III), Ni(II) and VO(IV) was synthesized with the bidentate Schiff base ligand (HL) derived from the condensation of 2-amino-3-benzyloxypyridine and 5-bromo salicylaldehyde. The synthesized Schiff base ligand and its metal complexes C1-C6 were structurally characterized by satisfactory elemental analysis, spectral studies such as (Mass, IR, 1H and 13C NMR, conductance measurement, UV-vis and magnetic measurements) and thermal studies. The structure of HL was authenticated by X-ray single-crystal analysis. Hirshfeld surface analysis was carried out to understand the nature of intermolecular contacts, the fingerprint plot provides the information about the percentage contribution. Square-pyramidal geometry is proposed for VO(IV) complexes whereas octahedral geometry for Co(III) and Ni(II) complexes. The Schiff base ligand and its metal complexes have been tested in vitro for their antibacterial activities by using well diffusion method against Gram positive bacteria B. subtilis, S. aureus and Gram negative bacteria S. typhi, E. coli and antifungal activities against A. niger, A. flavus, C. albicans and A. Solani. The antimicrobial activity data show that metal complexes are more potent than the parent ligand