Preparation of π-conjugated polythiazoles and their electrically conducting properties

Poly(thiazole-2,5-diyl) (PTz), poly(4-methylthiazole-2,5-diyl) (PMeTz) and poly(4,4′-dimethyl-2,2′-bithiazole-5,5′-diyl) (PMeBTz) are synthesized by dehalogenation polycondensation of the corresponding dibromothiazoles with zero-valent nickel complexes. PTz and PMeTz are soluble in formic acid and trifluoroacetic acid, whereas PMeBTz is soluble in trifluoroacetic acid. PTz and PMeBTz have weight-average molecular weights (Mw) of 5.9 × 104 and 3.2 × 103, respectively, as determined by a light scattering method. The UV-Vis spectra of PTz, PMeTz and PMeBTz show π-π∗ absorption peaks at 421 nm (in formic acid), 420 nm (in formic acid) and 425 nm (in trifluoroacetic acid), respectively. These absorption peaks are shifted to longer wavelength compared with that (λmax = 233 nm) of thiazole. Sodium doping of polythiazoles affords semiconducting materials with conductivity (σ) values of an order of 10−4 S cm−1.