Walter John - Inorganic Materials Research Laboratory, Department of Pure and Applied Chemistry, University of Calabar, Nigeria.
Ayi Ayi - Inorganic Materials Research Laboratory, Department of Pure and Applied Chemistry, University of Calabar, Nigeria.
Chinyere Anyama - Inorganic Materials Research Laboratory, Department of Pure and Applied Chemistry, University of Calabar, Nigeria.
Providence Ashishie - Inorganic Materials Research Laboratory, Department of Pure and Applied Chemistry, University of Calabar, Nigeria.

1-ethyl-3-methylimidazolium acetate (EMIMOAC) and 1-buthyl-3-methylimidazolium acetate (BMIMOAC) ionic liquids have been used as a solvent and stabilizing agent in an attempt to prepare cobalt nanoparticles via chemical reduction method. The SEM and UV-Vis techniques confirm the formation of nanoparticles. XRD reveals the nanocrystalline nature of the products with average crystallite size of 27.5 and 24.1 nm for CoEMIMOAC and CoBMIMOAC, respectively. The SEM and EDAX morphological/atomic weight ratio analyses show not much difference between the nanocrystals formed in EMIMOAC or BMIMOAC. These results indicate that the cationic part of the ionic liquid did not play significant role during nucleation and growth of the particles. The zone of inhibition of CoEMIMOAC obtained against Staphylococcus aureus and Escherichia coli are 23 and 14 mm, respectively whereas that of CoBMIMOAC against the bacterial under investigation is 15 mm. The synthesized nanocrystals have therefore demonstrated great potentials as nanodrugs in the treatment of infections caused by gram-positive microorganisms.

nanocrystals, Ionic Liquids, Chemical reduction, Nanoparticles, Antimicrobial activities