Self-condensation-type direct arylation synthesis of naphthalene bisimide-bithiophene alternating copolymers

The self-condensation-type direct arylation of naphthalene bisimide (NBI)-bithiophene alternating copolymers (PNBI2T), which was classified as one of high-performance acceptor polymers in organic field-effect transistors and organic photovoltaics, was developed. A new AB-type NBI monomer (NBI2T-Br) was designed for the self-condensation-type direct arylation. A PNBI2T was successfully synthesized by using NBI2T-Br; as a result of screening of the reaction conditions, the PNBI2T with M _n = 13,000 was obtained in the high yield (87 %) in the presence of Pd(OAc)₂, PCy₃·HBF₄, PivOH, and K₂CO₃. Furthermore, analyses of spectroscopy, optical, electrochemical, and thermal properties indicated that the PNBI2T with the desired structure was synthesized by the self-condensation-type direct arylation.