Sonochemical synthesis and characterization of new nanostructures cobalt(II) metal-organic complexes derived from the azo-coupling reaction of 4-amino benzoic acid with anthranilic acid, salicylaldehyde and 2-naphtol

Nanostructures of three new cobalt(II) complexes, (CoL1)·0.5DMF·1.5MeOH (1), [H2L1 = 5-(4-Carboxy phenyl azo) anthranilic acid], (Co(L2)2)·1.5MeOH (2), [HL2 = 5-(4-Carboxy phenyl azo) salicylaldehyde] and (Co(L3)2)·0.5 DMF·0.5MeOH (3), [HL3 = 1-(4-Carboxy phenyl azo) 2-naphtol], have been synthesized by the reaction of H2L1, HL2 and HL3 with Co(OAc)2·4H2O through sonochemical process. Calcination of the nano-sized compounds 1-3 yield Co3O4 nanoparticles at 450 °C under air atmosphere. These nanostructures were characterized by X-ray powder diffraction (XRD) and Scanning Electron Microscopy (SEM). Thermal stability of compounds 1-3 was studied by thermogravimetric (TG) and differential thermal analyses (DTA).