Electrochemical study of the mixed ligand complexes of Co(II) and Ni(II) with acetylsalicylic acid and nicotinamide

The interaction of acetylsalicylic acid (aspirin, aspH) and nicotinamide (NA) with Co(II) and Ni(II) ions was investigated using square-wave and cyclic voltammetry techniques. In the presence of Ni(II)/Co(II), nicotinamide gave new peaks at -0.85 V and -1.12 V, corresponding to the reduction of Ni(II)-nicotinamide (log beta(1:2)=5.97) and Co(II)-nicotinamide (log beta(1:2)=5.19) complexes, respectively. In the presence of Ni(II)/Co(II), acetylsalicylic acid gave new peaks at -0.91 V and -1.19 V, respectively, corresponding to the reduction of Ni(II)-salicylate (log beta(1:2) = 8.48) and Co(II)-salicylate (log beta(1:2) = 8.14) complexes. In the presence of nicotinamide, Ni(II)-salicylate and Co(II)-salicylate form mixed ligand complexes, reducing at -0.78V (log beta1:2:2 = 9.68) and -1.14V (log beta(1:2:2) = 8.64), respectively.