Poly(o-aminophenol) with two redox processes: A spectroelectrochemical study

Poly(o-aminophenol) has been synthesized potentiostatically at different electrode potentials in aqueous acidic solution. The cyclic voltammograms of the POAP films synthesized at relatively low electrode potentials (ESCE = 0.70…0.80 V) exhibit two redox processes with a mid point potential between the respective redox potentials ESCE = 0.29 V showing that the redox transition of the POAP from its reduced to completely oxidized state occurs via two consecutive reactions. The polymer has been studied with in situ UV–Vis and in situ Raman spectroelectrochemistry. The nature of a Raman band observed around 1645 cm−1 with red Kr+ laser excitation (647.1 nm) is discussed. The intensity of this band grows during a positive potential shift up to a maximum, located at about ESCE = 0.30 V, and then decreases with a further potential shift indicating the existence of intermediate species during the redox transformation of the polymer.