A self-doped oligoaniline with two stable redox couples in a wide pH range

Abstract

2,3-Dicarboxyaniline in its anionic state is oxidatively polymerized in aqueous solution by Na 2 S 2 O 8 as an oxidant to yield oligo(2,3-dicarboxyaniline) as a novel oligoaniline. XPS analysis reveals that the structure of the resulting oligomer is 61% quinoid and 39% benzenoid with ca. 21% self-droping degree. The resulting oligoaniline shows two stable redox couples over a wide pH range on the electrode. Both redox processes involve 1 electron transfer with 1 proton transfer in each 2 monomer units, a redox chemistry that is quite distinct from conventional polyaniline. The redox activity of the resulting polymer in pseudo-neutral conditions is caused by the carboxy group with high density which acts as a proton source for the protonation on the nitrogen atom of the polyaniline chain.