Highly Conductive Poly(phenylene thienylene)s: m -Phenylene Linkages Are Not Always Bad

Two isomeric polymers, which contain meta- or para-phenylene linkages between conducting segments, were synthesized and compared by electrochem. methods. The nonconjugated poly(1,5-diacetoxy-m-phenylene tetrathienylene) (PMPT-OAc) showed similar electroactivity to the para-isomer, poly(2,5-diacetoxy-p-phenylene tetrathienylene) (PPPT-OAc), in the cyclic voltammetry and in-situ cond. measurements. Spectroelectrochem. showed a similar buildup of sub-band-gap electronic transitions. Deacetylation of the polymers was performed successfully by reaction with hydrazine, producing PMPT-OH and PPPT-OH. Both phenol-substituted polymers exhibited greater electroactivity than the acetoxy-substituted polymers. In addn., the phenol substituents were found to lower the “turn-on” potential in the cond.-potential profile for PMPT-OH, but not for PPPT-OH. An alkoxy-substituted PMPT-OMe shows electroactivity similar to that of PMPT-OAc in the cyclic voltammetry, in-situ cond., and spectroelectrochem. [on SciFinder(R)]