A cross-coupling reaction between dihaloarylene monomers and unsubstituted arylene monomers in the presence of a palladium catalyst, the so-called palladium-catalyzed direct arylation, has been paid numerous attention for environmentally-friendly, efficient, and low-cost method for the synthesis of conjugated polymers compared to conventional cross-coupling reaction, such as Stille coupling reaction and Suzuki coupling reaction. In recent years, the synthesis of conjugated donor polymers by direct arylation has been reported; in contrast to synthesis of conjugated donor polymers, the direct arylation synthesis of conjugated acceptor polymers is far less developed. Horie et al. reported the synthesis of a naphthalene bisimide (NBI)-based acceptor polymer, a potential acceptor polymer for organic photovoltaics and organic field-effect transistors,by direct arylation; however, the molecular weight of the obtained NBI-based acceptor polymer was extremely low (Mn~ 2000). Such a low molecular weight does not meet the requirements for the device applications, which may cause the low stability and low performance of devices; therefore, the development of conjugated acceptor polymers with high molecular weights by direct arylation remains a big challenge.In this work, we found that efficient direct arylation methodology for the synthesis of a NBI-based acceptor polymer (PNBI3T-Dr  ) using a newly designed thiophene-extended NBI monomer under the optimal reaction conditions, which yielded a polymer with a high molecular weight (Mn> 30000) in a relatively high yield. To the best of our knowledge, our work is the first example for the efficient synthesis of conjugated acceptor polymers by direct arylation. This result revealed that direct arylation could be an alternative synthetic method even for conjugated acceptor polymers.

Efficient direct arylation approach to synthesize naphthalene bisimide-based acceptor polymers

248th National Meeting (2014)

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