A novel polyfluorene derivative electrodeposited by direct anodic oxidation of 9-bromofluorene in boron trifluoride diethyl etherate and trifluoroacetic acid

Poly(9-bromofluorene) (PBFe) film, a novel polyfluorene derivative, was synthesized electrochemically by direct oxidation of 9-bromofluorene (BFe) in boron trifluoride diethyl etherate (BFEE) mixed with 15% (by volume) trifluoroacetic acid (TFA) for the first time. The oxidation potential of BFe in this medium was measured to be only 1.30 V vs. SCE, which was much lower than that determined in acetonitrile + 0.1 mol L−1 Bu4NBF4 (1.70 V vs. SCE). Dedoped PBFe films were partly soluble in dimethyl sulfoxide (DMSO) and ethanol. PBFe films obtained from this medium showed good electrochemical behavior even in concentrated sulfuric acid. The structure and morphology of the polymer were studied by UV–vis spectroscopy, FT-IR spectroscopy, 1H NMR spectroscopy, MALDI–TOF mass spectrometry and scanning electron microscopy, respectively. The results of quantum chemistry calculations and the spectroscopies of dedoped PBFe indicated the polymerization mainly occurred at C(2) and C(7) positions. Fluorescent spectral studies indicate that PBFe is a good blue light emitter. Thermal Analysis implied PBFe films had better thermal stability compared with polyfluorene and poly(9-fluorenone).