Preparation of antiferromagnetic Co3O4 nanoparticles from two different precursors by pyrolytic method: in vitro antimicrobial activity

Abstract

Two varieties of Co₃O₄ nano particles (Co₃O₄-I and Co₃O₄-II) have been synthesized from two different precursors using a pyrolytic technique. Co₃O₄-I was prepared by using a coordination polymer [Co(dca)₂(2-benzoylpyridine)]_n (dca = dicyanamide) as sole precursor, whereas Co₃O₄-II was obtained from a dinuclear complex [Co₂(HL)(OAc)₂](OAc)₂·4H₂O [HL = 2,6-bis(N-ethylpiperazine-iminomethyl)-4-methyl phenol]. The synthesized nanoparticles were characterized by FTIR spectroscopy, magnetic measurements and X-ray diffraction studies. Both Co₃O₄-I and Co₃O₄-II are high-quality mono-dispersed, stable and defect-free nanoparticles. The surface morphology of these nanoparticles was revealed by scanning electron microscopy. Co₃O₄-I nanoparticles have square shape and size ranging from 10 to 25 nm, whereas Co₃O₄-II nanoparticles have hexagonal shape with larger particle size (100–150 nm). The size distribution of the nanoparticles was determined by dynamic light scattering. The particle size and microstructure were studied by transmission electron microscopy (TEM) images. These nanoparticles show an effective anti-microbial activity, employing Staphylococcus aureus and Escherichia coli as model microbial species, evidenced from the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values.