Structure-controlled electrodeposition and electrochemical behavior of films from isomeric diphenols at the solid-liquid interface

The deposition efficiency and the electrochemical properties, as well as the thickness and hydrophilicity, of the coatings obtained from catechol (1,2-benzenediol), resorcinol (1,3-benzenediol) and hydroquinone (1,4-benzenediol) at pH 5.0 have been compared with the aid of cyclic voltammetry, chronoamperometry and electrochemical impedance spectra on carbon and gold working electrodes. Coating electrodeposition was found to be more efficient in the case of resorcinol than for catechol whereas no detectable coating was formed from hydroquinone. Both quinone-forming isomers, catechol and hydroquinone, displayed reversible electrochemical properties with a reduction current following the initial oxidation wave, whereas resorcinol displayed a markedly decreasing oxidation current in the second cycle, denoting thus an irreversible process. These and other results were rationalized in the light of the divergent oxidation chemistries of the isomeric benzenediols, paving the way to novel structure-property relationship studies for coating design and tailoring. Anyway thick and hydrophilic coatings can be obtained easily and in a short time as shown on gold working electrodes.