Electropolymerization of 1,4-bis(pyrrol-2-yl)benzene in the presence of the easily oxidized electrolyte sodium tetraphenylborate

The low oxidation potential of 1,4-bis(pyrrol-2-yl)benzene (BPB) at 0.25 V vs. Ag/Ag+ allows its electropolymerization in the presence of easily oxidized electrolytes, such as sodium tetraphenylborate (NaBPh(4)). In contrast, the electropolymerization of pyrrole under the same conditions is unsuccessful due to electrolyte breakdown. The resulting conducting polymer, poly[1,4-bis(pyrrol-2-yl)phenylene tetraphenylborate], is highly electroactive with a low oxidation potential (E(12p) = 0.0 V vs. As/Ag+) for formation of the conducting state. Electrochemical quartz crystal microbalance studies indicate that the BPh(4)(-) anions in the polymer film and electrolyte serve as the mobile dopant ions, moving into and out of the film, when the polymer is electrochemically switched between oxidized and reduced states.