Synthesis, spectral characterization, crystal structure and antibacterial activity of nickel(II), copper(II) and zinc(II) complexes containing ONNO donor Schiff base ligands

In the present study, a series of mononuclear Ni(II), Cu(II) and Zn(II) complexes with ONNO donor salentype Schiff base ligands, derived from different 3,5-dihalosalicylaldehyde with polymethylenediamines of varying chain length, have been prepared. All the synthesized compounds were characterized by using various spectroscopic (FT-IR and I H NMR) and analytical (CHN etc.) techniques. Furthermore, three complexes (ZnL1, NiL3 and NiL4) were successfully characterized by single crystal X-ray diffraction. The data revealed that the geometry around Zn(II) was distorted square pyramidal for ZnL1, while NiL3 and NiL4 complexes adapted slightly distorted octahedral geometries around Ni(II). The antibacterial activities of the synthesized ligands and their respective complexes were elaborated by screening them against two strains of Gram positive (Staphylococcus aureus and Bacillus cereus) and two strains of Gram negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. It was found from the measurements of zones of inhibition that metal chelates are marginally more effective than free ligands. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, a series of mononuclear Ni(II), Cu(II), and Zn(II) complexes with ONNO donor salentype Schiff base ligands were prepared and characterized. The antibacterial activities of the synthesized compounds were tested, with metal chelates showing slightly better effectiveness than free ligands.