<b>Comparative synthesis and characterizations using solution-based and mechanochemical methods on Ni (II) AND CD (II) chelates of paracetamol and aspirin</b><b></b>

This paper reported the Mechanochemical synthesis of Cd(II) and Ni(II) complexes of aspirin and paracetamol by simple grinding of their metal chlorides in the absence of solvent. The conventional (solution-based) method for the synthesis of the above complexes was also reported for comparison purposes. The products obtained from both methods were characterized by IR analyses, solubility test, melting point determination, conductivity measurement and magnetic moment. The IR spectral and analytical data of the complexes were similar for both products of the two synthetic routes, thus, suggesting the formation of identical compounds. Job's method analyses suggested 1:2 metal to ligand ratio for both paracetamol and aspirin complexes. All the complexes have high molar conductance values (109.42 to 207.61 Ω-1cm2mol-1) for aspirin complexes and (77.32-100.22 Ω-1cm2mol-1) for paracetamol complexes indicating their electrolytic nature in dimethyl sulfoxide (DMSO). The complexes were all soluble in dimethyl formamide (DMF) and DMSO. Paracetamol complexes were found to be soluble in acetone and diethyl ether (DEE) while Aspirin was found to be soluble in methanol, DMF and DMSO whereas its complexes were all found to be insoluble in water. The magnetic moment values indicates that Ni(II) complexes are paramagnetic while cadmium complexes are diamagnetic. The complexes decompose at a temperature range of 167.8-189.6°C higher than those of their ligands revealing their higher thermal stability compared to the ligands 170 °C and 137 °C for paracetamol and aspirin respectively.