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

Abstract

AbstractPoly[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.