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.
