Ionochromic and Thermochromic Phenomena in a Regioregular Polythiophene Derivative Bearing Oligo(oxyethylene) Side Chains

Abstract

Structural, thermal, and optical studies on regioregular poly[3-oligo(oxyethylene)-4-methylthiophene] have revealed interesting thermochromic and ionochromic effects related to a planar/nonplanar transition of the conjugated backbone. This first-order-like conformational transition (formation of twistons) seems driven by side-chain disordering induced by an increase of temperature or through noncovalent interactions with specific cations. The twisting of one repeat unit of this regioregular polythiophene derivative provokes the twisting of a large number of adjacent thiophene units (a domino effect) which leads to an amplification of the resulting optical (i.e., absorption or emission band) signal. These features are particularly promising for the development of novel affinitychromic and photochromic sensors based on new regioregular poly(3-alkoxy-4-methylthiophene)s.

Synthesis and Physical Properties of Regioregular Poly(3-alkoxy-4-methylthiophene)s

“…If PMThO derivatives were a regiorandom structure in the polymer backbone, 16 sets of 13 C resonances are detected. 9,12,18,19 The 13 C NMR spectrum of PMThO derivatives supports the interpretation of the 1 H NMR data. 1 H NMR and 13 C NMR data of PMThO derivatives demonstrate that PMThO derivatives with regioregular structure in the polymer backbone can be easily obtained by the conventional oxidative polymerization using iron trichloride as a catalyst.…”

“…Leclerc et al reported that regioregular 3,4-disubstituted PTh derivatives were obtained by chemical oxidation of the relative monomers by iron trichloride. [14][15][16][17][18][19] This method is very easy way to obtain regioregular PTh derivatives compared to the synthetic methods using Rieke zinc y To whom correspondence should be addressed (Tel: +81-3-5228-8248, Fax: +81-3-3235-2214, E-mail: nkoide@ch.kagu.sut.ac.jp). or nickel catalyzed cross-coupling.…”

The Chemistry of Conducting Polythiophenes

“…[167] This type of discovery is yet another indication that regioregularity is an important factor in the development of ionoselective sensors.…”

Structure dependence of photochromism and thermochromism of azobenzene-functionalized polythiophenes

“…Upon heating, an absorption band at 560 nm related to a planar (or nearly planar) conjugated backbone showed a decrease, meanwhile a new absorption band located at 446 nm appeared and gradually increased with increasing the heating temperature. The latter is characteristic of a delocalized twisted (less conjugated) form of the polythiophene backbone [14]. This absorbance change is fully reversible, and, upon cooling, the COP64 film recovers its initial absorption spectrum.…”