Facile Syntheses of Dioxythiophene-Based Conjugated Polymers by Direct C–H Arylation

Various substituted dioxythiophenes bearing 3,4-propylenedioxythiophenes (ProDOT) and 3,4-ethylenedioxythiophene (EDOT) moieties successfully undergo Pd-catalyzed direct C–H arylation to yield π-conjugated polymers. The effects of palladium catalysts, phosphine ligands or additives, and functional groups on this facile polycondensation approach are investigated. Polymers from alkoxy-substituted ProDOT are synthesized with reasonable molecular weight (Mn = 6100–9600) and low PDI (1.3–1.9). Four substituted EDOT with alkoxy or protected functional groups also undergo direct C–H arylation polycondensation to yield corresponding polymers. The obtained polydioxythiophenes exhibit UV–vis absorptions ranging from 480 to 590 nm, and these conjugated polymers are electroactive and reversibly switched between the oxidized and neutral states upon applying potentials.