Spectroelectrochemical behaviour of poly(2,5-dithienylene-isothianaphthene) and its analogue deuterated on the benzene ring

Poly(2,5-dithienylene-isothianaphthene) and its analogue, deutered on the b enzene ring, have been prepared by voltammetric polymerization of the corre sponding monomers in Bu4NBF4/acetonitrile solutions. The polymers obtained are electroactive, showing in cyclic voltammograms two oxidation peaks asso ciated with p-type doping and two reduction peaks, originating from the de- doping process. The use of the polymer deuterated selectively on the benzen e ring significantly facilitated the interpretation of Raman spectroelectro chemical data, since it allowed for a differentiation between the bands, or iginating from the benzene ring and those characteristic of the thiophene b ackbone. Similarly as cyclic voltammetry, Raman spectroelectrochemistry sho ws that the oxidative doping of the polymer is a two-step process. The spec tral changes observed for the first step of the oxidation are consistent wi th the formation of the quinonoid sequence of bonds upon doping.