Electroactivity of Electrochemically Synthesized Poly(Aniline Boronic Acid) as a Function of pH: Role of Self-Doping

The influence of pH on the electrochemical behavior of electropolymerized, self-doped poly(aniline boronic acid) thin films in the presence of d-fructose has been investigated with voltammetry and potentiometry in phosphate-buffered saline solution. It was found that the complexation of boronic acid with d-fructose and subsequent formation of self-doped polymer extends the electroactivity of poly(aniline boronic acid) to neutral and alkaline media in a manner similar to that of other self-doped polyanilines. However, the electroactivity exhibits more complex pH-dependent behavior, suggesting a transition between species involved in the self-doping process. Results obtained with in situ UV−vis spectroscopy and ex situ FTIR spectroscopy in conjunction with 11B and 19F NMR studies of monomeric species indicate that the self-doped structure of poly(aniline boronic acid) is pH sensitive and that the anionic boronic acid complex involves either fluoride or hydroxide depending on pH.