Direct arylation polymerization : a green, streamlining synthetic approach to π-conjugated polymers

Transition-metal-catalyzed aryl-aryl coupling though C-H bonds activation, termed direct arylation, has been widely used in synthesis of a broad range of small molecules. In contrast to traditional coupling methods such as Suzuki coupling and Stille coupling, direct arylation does not involve tedious preparation of unstable, toxic organometallic reagents. Despite these advantages, direct arylation has not been applied to synthesis of π-conjugated polymers until recently. In this perspective, we summarize the progress of direct arylation polymerization for synthesis of various π-conjugated polymers, including homopolymers of polythiophene derivatives and donoracceptor alternating copolymers. We also discuss present challenges and future directions of this nascent methodology of polymerization for synthesis of functional π-conjugated polymers that can find applications in optoelectronic devices such as solar cells and field effect transistors