Electrosyntheses of freestanding polyindole films in boron trifluoride diethyl etherate

High-quality freestanding polyindole (PIn) films were synthesized electrochemically through the direct oxidation of indole in pure boron trifluoride diethyl etherate (BFEE). The oxidation potential of indole in this medium was measured to be only 0.86 V versus a saturated calomel electrode, which was lower than that determined in acetonitrile/0.1 mol L-1 Bu4NBF4. PIn films obtained from this medium showed better electrochemical behavior and better thermal stability with a conductivity of 10(-1) S cm(-1), and this indicated that BFEE was a better medium than acetonitrile for the electrosyntheses of PIn films. Structural studies showed that the polymerization of indole ring occurred at the 2,3-position. As-formed PIn films could be partly dissolved in acetone, acetonitrile, tetrahydrofuran, and so forth. Fluorescent spectral studies indicated that PIn was a good blue-light emitter. To the best of our knowledge, this is the first report on the fluorescence of PIn. (c) 2005 Wiley Periodicals, lnc.