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), [H2 L1 =5-(4-Carboxy phenyl azo) anthranilic acid], (Co(L2 )2 )·1.5MeOH (2), [HL2 =5-(4-Carboxy phenyl azo) salicylaldehyde] and (Co(L3 )2 )·0.5DMF·0.5MeOH (3), [HL3 =1-(4-Carboxy phenyl azo) 2-naphtol], have been synthesized by the reaction of H2 L1 , HL2 and HL3 with Co(OAc)2 ·4H2 O through sonochemical process. Calcination of the nano-sized compounds 1-3 yield Co3 O4 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).