Synthesis, spectroscopic and antimicrobial properties of Co(II), Ni (II) and Cu(II) complexes of (E)-N’-(2-hydroxy -5-nitrobenzylidene)isonicotinohydrazide)

The objective of this study is to investigate the antimicrobial activity of novel Schiff base metal complexes. The resistance of micro-organisms to classical antimicrobial compounds poses a challenge to effective management and treatment of some diseases. In line with this, copper (II), nickel (II) and cobalt (II) complexes of the Schiff base ligand (E)-N’-(2- hydroxy-5-nitrobenzylidene) isonicotinohydrazide) were synthesized and characterized based on elemental analysis, conductivity measurements, infrared and electronic absorption spectroscopy. The results suggest a 1:2 [M:L] stoichiometry for the copper and cobalt complexes and a 1:1 [M:L] ratio for the nickel complex. The electronic absorption spectral data support octahedral geometry for cobalt(II) and copper(II) complexes and square planar for nickel (II). In-vitro antimicrobial properties of the compounds evaluated against five pathogenic bacteria using the agar-well diffusion method revealed that the activity was in the order Ni>Co>Cu. These compounds can be used as substrates for development of new antimicrobial agents.Keywords: isonicotinohydrazide, Schiff base metal complexes, in-vitro, antimicrobial activity, electronic spectra, 2-hydroxy-5-nitrobenzaldehyd