New synthetic routes to poly(isothianaphthene): III. Polymerization of dithiophthalide and 1,1,3,3-tetrachlorothiophthalan

In this paper, the polymerization of sulfur-containing precursor molecules to poly(isothianaphthene) (PITN) is described. Most attention has been devoted to the polymerization of dithiophthalide, as other useful precursors were synthetically less accessible. The thermal polymerization of dithiophthalide leads to the formation of undoped PITN, which had a conductivity in the order of 10−4 S cm−1. The insoluble polymer was characterized by IR, Raman and solid state NMR spectroscopy, and elemental analysis. The polymerization proceeds by simply heating the precursor without the presence of any added reagent or solvent and is the first non-oxidative route to PITN.