The polycondensation product of 3,7-diamino-2,8-dimethyl-5-phenylphenazinium chloride and 2,3,5,6-tetrachloro-1,4-benzoquinone: a new semiconducting ladder polymer

We report the synthesis and characterization of a new semiconducting ladder polymer. The polymer is synthesized from the polycondensation reaction of 3,7-diamino-2,8-dimethyl-5-phenylphenazinium chloride with 2,3,5,6-tetrachloro-1,4-benzoquinone in an acidic solvent, an organic solvent or the solid phase. We have employed a model reaction between 2,3,5,6-tetrachloro-1,4-benzoquinone and 2-aminotoluene to aid in the characterization of the polymer. This model reaction results in the synthesis of the pentacyclic compound 6,13-dichloro-5,12-dihydro-5,12-diazapentacene (DCDHDAP). Evidence for the polymer structure is provided by elemental analysis and the close match of the Fourier-transform infrared (FT-IR) spectra of the polymers with that of the model compound. The d.c. electrical conductivity of the polymer varies slightly depending on the polymerization method. Variations from 8.0 × 10−6 S cm−1 for the polymer prepared in polyphosphoric acid (PPA) to 7.2 × 10−8 S cm−1 for the polymer prepared in dimethylacetamide (DMAC) and 2.2 × 10−7 S cm−1 for the polymer prepared in the solid phase are observed. Preliminary doping experiments show that there is no increase in conductivity upon doping with iodine.