Electrochemical Reduction of NAP on the Glassy Carbon Electrodes Modified with Aromatic Diazonium Salts

The electrochemical reduction of 4-{[(1E)-(2-hydroxynaphthyl)methylidene]amino}-1,5-dimethyl-2-phenyl- 2,3-dihydro-1H-pyrazol-3-one (NAP) was studied by using cyclic voltammetry in acetonitrile media at a glassy carbon (GC) and modified GC electrodes. The GC electrodes were grafted by electrochemical reduction of diazonium salts of various organic molecules. GC surfaces modified with anthraquinone, p-nitrophenyl, p-aminophenyl, p-amino-N,Ndimethylphenyl and p-methoxyphenyl radicals were used to investigate the reduction behaviors of NAP. The effect of the modified glassy carbon electrodes on the reduction of NAP was studied as being related to the role of the electron donor or the electron acceptor groups on the phenyl ring attached to the surface. The compound NAP shows two reduction peaks in a cyclic voltammogram. These peaks were observed at -2.1 V and -2.7 V on the GC electrode surface. Also, the reduction peaks of NAP were obtained for all the modified electrodes studied. The p-methoxyphenyl modified GC electrode showed a significant increase in the rate of electron transfer at the reduction of NAP. The kinetics and the mechanism of the electrode process were simulated and some parameters were calculated using BAS Digi-Sim® software.