Electrochemical studies of 1,3,7,9-tetramethyluric acid in aqueous and micellar media

The electrochemical behaviour of 1,3,7,9-tetramethyluric acid has been studied in the phosphate buffers in the pH range 2.2–8.9 at PGE by linear and cyclic sweep voltammetry, spectral studies, controlled potential electrolysis and related techniques. The oxidation occurred in a single pH independent 2e step to give an unstable diimine which decomposed in a chemical follow-up step. Due to the presence of four methyl groups in tetramethylateduric acid, positive charges at position N1 and N3 are produced due to canonical structures and at N9 due to protonation. It was observed that the positive charges at methylated nitrogen atoms greatly affect the peak potential values, rate of reaction and the products. The kinetics of decomposition of UV absorbing intermediate generated during electrooxidation of 1,3,7,9-tetramethyluric acid at pH 7.2 becomes so fast that it is not possible to detect the decay of the UV-absorbing intermediate. The surfactants have been found to significantly affect the electrode reaction parameters. Cationic surfactant catalyses the electron transfer at electrode surface. A detailed interpretation of the redox mechanism of tetramethylated uric acid in aqueous and micellar systems has also been suggested.