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 pi-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 (M-n = 6100-9600) and low PDI (1.3-1.9). Four substituted EDOT with alkoxy or protected functional groups also undergo direct C-H arylation poly-condensation 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.