Pd-catalysed oxidative C-H/C-H coupling polymerization for polythiazole-based derivatives

- Pd-catalysed oxidative C-H/C-H coupling reaction achieves the homopolymerization of thiazole derivatives.
- Conjugated polythiazole derivatives exhibit interesting photoelectric properties.
- This synthetic strategy is expected to be applied in direct oxidative C-H/C-H coupling polymerization of other heteroarenes.

Pd-catalysed oxidative C-H/C-H coupling homopolymerization of thiazole derivatives with different numbers (n = 1-3) of thiophene as bridged units was described. It represents a facile and practical methodology to prepare thiazole-based conjugated polymers in excellent yields. Three conjugated polythiazole derivatives (P1-P3) were synthesized by utilization of ligand-free Pd(OAc)2 as a catalyst in the presence of Ag2CO3 and KOAc. Their chemical structure and molecular weights were established by 1H and 13C NMR, as well as size exclusion chromatography (SEC), respectively. Polymerization conditions including amounts of Pd(OAc)2 and oxidant, solvent medium and other catalysts were screened and optimized. Furthermore, the optical and electrical properties of the resulting polymers P1-P3 were investigated by UV-vis and fluorescent spectroscopy, as well as cyclic voltammetry, respectively, and the influence of the length of bridged units on the photoelectric properties of these polymers was also discussed. This synthetic strategy would be applied in direct oxidative C-H/C-H coupling polymerization of other heteroarenes to construct versatile π-conjugated polymers for optoelectronic applications.