Direct arylation polycondensation of chlorinated thiophene derivatives to high-mobility conjugated polymers

High-mobility conjugated polymers (CPs) that can be synthesized in a large scale by direct arylation polycondensation (DArP) are highly desired for printable electronics. To realize this purpose, a readily accessible C-H monomer with high reactivity and selectivity is crucial. Herein, we demonstrated that chlorination enables the efficient DArP of thiophene derivatives, i.e., 3,3′,4,4′-tetrachloro-2,2′-bithiophene (4ClBT) and (E)-1,2-bis(3,4-dichlorothien-2-yl)ethene (4ClTVT), which can be prepared with no more than two steps. No evidence of structure defects was found in the resulting polymers. This finding allows the facile synthesis of high-molecular-weight CPs via DArP. The presence of Cl···S weak intramolecular interaction, which can improve the coplanarity of conjugated skeleton, was confirmed by single-crystal structural analysis. With diketopyrrolopyrrole derivatives as C-Br monomers, CPs with electron mobility up to 1.44 cm2 V-1 s-1 in air have been obtained via DArP. This work demonstrates that chlorinated thiophene derivatives are promising C-H monomers for large-scale synthesis of high-mobility CPs via an atom-economical and green method, i.e., DArP. © 2020 American Chemical Society.