Polyazetidine-Coated Microelectrodes: Electrochemical and Diffusion Characterization of Different Redox Substrates

The present paper reports on the diffusion characteristics and electron transfer properties of a membrane obtained from polyazetidine prepolyrner (PAP) consisting of repeating units of 1-(aminomethyl)-1-{2-[(6-oxy-hexane)amino]ethyl}-3-hydroxyazetidinium chloride studied in the presence of seven simple redox electroactive molecules: ABTS, catechol, dopamine, ferrocenecarboxylic acid, ferricyanide, ferrocyanide and the osmium complex bis(2,2-bipyridyl)-4-aminomethylpyridine chloride hexafluorophosphate (Os-[(bpy)(2) 4-AMP Cl](+)). Using water as medium, the apparent diffusion coefficients (D-app), the concentrations of the compounds in the membrane, and the heterogeneous rate constants (K-s) were calculated as a function of temperature, and the influence thereof on these parameters was evaluated. Even if D-app and k(s). values in the presence of PAP are smaller than in solution, this decrease is small enough to indicate that the PAP membrane shows excellent diffusion and electron-exchange properties with respect to other commonly used membranes reported in the literature.