Copolymers of thiophene and thiazole. Regioregulation in synthesis, stacking structure, and optical properties

Palladium-catalyzed polycondensation between 2,5-dibromo-4-alkylthiazoles (alkyl = butyl thorough nonyl) and 2,5-bis(trimethylstannyl)thiophene gave charge-transferred-type alternating polymers, PTz(R)Th's. PTz(R)Th's had a high regioregularity as judged from their H-1 NMR and X-ray diffraction (XRD) data, and the head-to-tail content was estimated to be higher than 90% from the H-1 NMR data. The polymer forms a stacked structure, and the stacked structure is proposed based on the XRD data. The tendency of the polymer to form the stacked structure is considered to contribute to the regioregulation in the polymerization. The polymer was susceptible to both electrochemical oxidation (or p-doping) and reduction (or n-doping).