During the second oxidation step, the oxidation of the aniline ring takes place, which triggers a chain of chemical reactions that leads to the formation of a variety of soluble compounds. In the literature, at least 10 different oxidation products have been reported resulting from the oxidation of the quinolone ring. The processes observed at negative potentials after TDMQ20 oxidations are also very complex, involving the participation of both chemisorbed species on the WE surface and the free TDMQ20 and oxidation products present in solution, as is demonstrated by the Bidim-SEC measurements. The definition of these electrochemical process is not optimal, probable because chemisorbed species generated during the oxidation could be partially blocking the electrode surface, as confirmed by electrochemical measurements, where is observed that subsequent oxidation cycles lead to the passivation of the electrode surface (Figure .7). For this reason, the height of the voltammetric peaks in the reduction process is considerable lower than in the oxidation process