Surface enhanced resonance Raman spectroelectrochemical study of electrochemically generated copolymer films of aniline and aminonaphthalenedisulfonates

Copolymers of aniline and either 2-aminonaphthalene-4,8-disulfonic acid, or 2-aminonaphthalene-6,8-disulfonic acid, have been electrodeposited at a gold electrode, and studied by the means of in situ surface enhanced resonant Raman spectroelectrochemistry. Characteristic Raman features have been identified, and their dependencies on the electrode potential have been discussed. The nature of Raman band, observed at ca. 1630 cm−1 with the red He-Ne laser excitation (632.8 nm), is discussed. The intensity of this band grows during a positive potential shift up to a maximum, located at ca. 0.4-0.5 V vs. Ag/AgCl, and then decreases with a further potential shift up to 1.0 V. Based on this, a possible alternate structure of electrogenerated copolymers has been discussed, which includes a ladder-type phenazin-like molecular unit. The “ortho-coupling” instead or parallel to the usual “para-coupling” has been suggested to proceed during electrocopolymerization of the monomers studied with aniline.