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

Abstract

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.

Helicenes: Synthesis and Applications

“…Recently another novel type of ladder polymer forming a one-dimensional wire, constructed from fused benzothiophene rings, was described by Nishide and co-workers (Scheme ) . In previous theoretical simulations they found that the conductivity of a helical molecular wire (like 669 ) could be greatly improved by chemical doping .…”

Structural and Electronic Properties of Poly(thiaheterohelicene)s

“…In basic environments, the dodecyl group can be removed from the soluble Poly-Sp giving place to the corresponding poly(thiaheterohelicene) (Poly-TH; Scheme 1b). 15 Interestingly, a previous study on a very similar system, that is, poly(phenylene-4-6-dithia-1,3-diyl), showed that a solenoid-like magnetism occurs upon electronic transmittance around the helical π-conjugated structure. 16 This feature suggests that poly(thiaheterohelicene)s are potential candidates for the construction of organic molecular-based electromagnets able to act as nanowires.…”

“…This ladder polymer showed a very stiff helical structure with extended π-conjugation. In basic environments, the dodecyl group can be removed from the soluble Poly-Sp giving place to the corresponding poly(thiaheterohelicene) ( Poly-TH ; Scheme b) . Interestingly, a previous study on a very similar system, that is, poly(phenylene-4−6-dithia-1,3-diyl), showed that a solenoid-like magnetism occurs upon electronic transmittance around the helical π-conjugated structure .…”

The hetero-Friedel-Crafts-Bradsher Cyclizations with Formation of Ring Carbon-Heteroatom (P, S) Bonds, Leading to Organic Functional Materials

“…Nishide and coworkers synthesized poly(thiaheterohelicene) (64) containing dibenzothiophene moieties. In this synthesis, the palladium catalyzed polycondensation of cyclic diboronic acid diesters (65) with 2,4-dibromo-1,5-di-n-dodecylthiobenzene (66) followed by oxidation of the sulfide to sulfoxide function with hydrogen peroxide provided polyphenylene (67), which was cyclized to the corresponding dibenzothiophene polymer (64) under strong acidic conditions via sulfonium derivative (68) (Scheme 12) [26]. Tuschida and coworkers synthesized a new type of polythiophene oligomers (69) by the cyclization reaction of bithienyls or terthienyls (70) to sulfonium derivatives (71) followed by aromatization with pyridine to give fused thieno-systems (69) (Scheme 13) [27].…”

“…Nishide and coworkers synthesized poly(thiaheterohelicene) ( 64 ) containing dibenzothiophene moieties. In this synthesis, the palladium catalyzed polycondensation of cyclic diboronic acid diesters ( 65 ) with 2,4-dibromo-1,5-di- n -dodecylthiobenzene ( 66 ) followed by oxidation of the sulfide to sulfoxide function with hydrogen peroxide provided polyphenylene ( 67 ), which was cyclized to the corresponding dibenzothiophene polymer ( 64 ) under strong acidic conditions via sulfonium derivative ( 68 ) ( Scheme 12 ) [ 26 ].…”