Poly(thiaheterohelicene) derived from the long‐alkylated polysulfonium precursor

Poly[4,6‐bis(dodecylthio)‐1,3‐phenylene‐ alt ‐2‐methyl‐1,3‐phenylene] (Poly‐S) was synthesized via Suzuki–Miyaura coupling of 1,3‐dibromo‐2,6‐bis(dodecylthio)benzene and 2‐methyl‐1,3‐phenylenebis(pinacol borate). After quantitative oxidation of the pendant sulfide moiety to the sulfoxide derivative (Poly‐SO), the m ‐linked benzene rings were fused via intramolecular ring‐closing condensation with excess triflic acid to form the corresponding poly(sulfonium cation) (Poly‐S + ) with a helical structure. Poly‐S + was quite soluble in non‐polar solvents due to the long alkyl dodecyl chain. The Poly‐S + film, especially the film cast from its acetone solution, gave a polarized optical micrograph, suggesting an oriented structure of the helical poly(sulfonium) derivative. The X‐ray diffraction pattern of the film supported a hexagonal columnar packing of the polymer. The polysulfonium derivative in the film state was converted to the corresponding poly(thiaheterohelicene) ( Poly‐TH ) via the dealkylation with a basic potassium hydroxide methanol solution or pyridine. The Poly‐TH film was doped with iodine. Its conductivity was enhanced about 30 times when compared to that of the undoped film. Copyright © 2008 John Wiley & Sons, Ltd.