A Highly Efficient Catalytic System for Polycondensation of 2,7-Dibromo-9,9-dioctylfluorene and 1,2,4,5-Tetrafluorobenzene via Direct Arylation

Direct arylation polymerization has attracted a great deal of attention as an efficient method for synthesizing π-conjugated polymers without the use of organometallic reagents. This paper describes that Pd2(dba)3·CHCl3 (0.5 mol %) and P(C6H4-o-OMe)3 (L1, 2.0 mol %), in conjunction with a carboxylic acid (AcOH or PivOH) and a base (Cs2CO3), exhibit high catalyst performance in polycondensation of 2,7-dibromo-9,9-dioctylfluorene and 1,2,4,5-tetrafluorobenzene. Unlike conventional catalytic direct arylation systems that have need to use highly polar solvents such as DMA and DMF, the present catalytic system is sufficiently reactive in THF and toluene to afford poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(2,3,5,6-tetrafluoro-1,4-phenylene)] (PDOF-TP) with extremely high molecular weight (Mn up to 347 700) in high yield.