Electrosyntheses And Characterizations Of Conducting Polymers With Fused-Ring Structure In Boron Trifluoride Diethyl Etherate

Conducting polymers (CPs) can be conveniently prepared by electrochemical oxidation of corresponding monomers. High-quality CPs obtained from fused-ring compounds by electrochemical polymerization have been investigated as an attractive class of functional materials in recent years. The solvent effect is an important factor during the process of electrosynthesis of CPs. The oxidation potentials of corresponding fused-ring monomers are commonly higher in common neutral solvents, which results in the destruction of the polymers and degradations of their properties. Thus, many efforts have been focused on the decrease of oxidation potentials of monomers in order to prepare high-quality CPs. Boron trifluoride diethyl etherate (BFEE), a middle strong Lewis acid together with good ionic conductivity, is a co-ordination complex obtained from BF3 and diethyl ether (EE) in 1:1 equiv. proportion. The interactions between BFEE and the fused-ring monomers can lower their corresponding oxidation potentials and the catalytic effect of BFEE facilitates the formation of high-quality polymer films. This dissertation focused on the electrosyntheses and characterizations of high-quality CPs prepared from six fused ring compounds in BFEE-based electrolytic system at low potentials.1. High-quality free-standing poly(5-methoxyindole) (P5MIn) films were synthesized electrochemically by direct anodic oxidation of 5-methoxyindole (5MIn) in BFEE. P5Min films obtained from this medium showed good electrochemical behavior and good thermal stability with a conductivity of 0.12 S cm-1. P5MIn films are insoluble in water, acetone and tetrahydrofuran. The structure of the polymer was studied by UV-visible spectroscopy and FT-IR spectroscopy, which indicated that the polymerization occurred at C2 and C3 position. Fluorescent spectral studies indicate that solid P5MIn film is a good blue-light-emitter. Thermal stability of P5MIn film is higher than poly(5-methylindole) obtained from BFEE.2. High-quality soluble poly(5-fluoroindole) (P5FIn) films were synthesized electrochemically by direct oxidation of 5-fluoroindole (5FIn) in BFEE. The oxidation potential of 5FIn in this medium was measured to be only 1.05 V vs. SCE, which was much lower than that determined in acetonitrile+0.1 mol L-1 Bu4NBF4 (1.30 V). P5FIn films obtained from this medium showed good electrochemical behavior and good thermal stability with a conductivity of 7.1×10-2 S cm-1. Dedoped P5FIn films are soluble in dimethyl sulfoxide. Fluorescent spectral studies indicate that P5FIn is a good blue-light-emitter. The structure and morphology of the polymer were studied by UV-vis spectroscopy, FT-IR spectroscopy, 1H NMR spectroscopy and scanning electron microscopy, respectively. The results of the spectroscopies of dedoped P5FIn indicate the polymerization mainly occurs at C2 and C3 positions.3. A novel conducting polymer, high-quality poly(fluorene-9-carboxylic acid) (PFCA) film, was synthesized electrochemically by direct anodic oxidation of fluorene-9-carboxylic acid (FCA) in boron trifluoride diethyl etherate (BFEE) containing a certain amount of trifluoroacetic acid (TFA). The oxidation potential of FCA in this medium was measured to be only 1.22 V vs. SCE. PFCA films obtained from this medium showed good redox activity and stability with a conductivity of 0.62 S cm-1. Optical properties were studied by UV-vis and fluorescent spectroscopy. Fluorescent spectral studies indicate that solid PFCA film is a good blue-light-emitter. The structure and morphology of the polymer were studied by UV-vis spectroscopy, FT-IR spectroscopy and scanning electron microscopy, respectively.4. High-quality poly(9,9-dichlorofluorene) (PDCF), a new part soluble polyfluorene derivative, was easily synthesized electrochemically by direct anodic oxidation of 9,9-dichlorofluorene (DCF) in BFEE containing 15%(by volume) TFA. It was hard for DCF to deposit on the electrode in neutral solvents such as CH3CN system. This methodology may help promotion of researches to reveal unknown properties and applications of polyfluorene materials. PDCF films with conductivity of 3.3×10-2 S cm-1 obtained from this media show good redox activity and thermal stability. The structure and morphology of the polymer were studied by UV-vis, FTIR, 1H NMR spectra, and scanning electron microscopy, respectively. The results of quantum chemistry calculations and the spectroscopies of dedoped PDCF indicate that the polymerization of DCF mainly occurs via C2 and C7 position. Fluorescent spectral studies indicate that PDCF film with high fluorescence quantum yields and photochemical stability is a novel green-light-emitter.5. High-quality polyphenanthrene (PPh) films were synthesized electrochemically by direct anodic oxidation of phenanthrene (Ph) in BFEE containing a certain amount of TFA. The oxidation potential of Ph in this medium was measured to be only 0.63 V vs. SCE, which was greatly lower than that determined in acetonitrile+0.1 mol L-1 Bu4NBF4 (1.55 V vs. SCE). PPh films obtained from this medium showed good redox activity and stability even in concentrated sulfuric acid. Dedoped PPh films were partly soluble in polar solvent such as CH2Cl2, acetone, tetrahydrofuran, and dimethyl sulfoxide. Fluorescent spectral studies indicate that PPh is a good blue-light-emitter. The structure and morphology of the polymer were studied by UV-vis spectroscopy, FTIR spectroscopy, 1H NMR spectroscopy, and scanning electron microscopy, respectively. The results of quantum chemistry calculations of Ph monomer and the spectroscopies of dedoped PPh indicated the polymerization mainly occurred at C9 and C10 positions.6. High-quality poly(9,10-dihydrophenanthrene) (PPh) with good fluorescene properties was synthesized electrochemically by direct anodic oxidation of 9,10-dihydrophenanthrene (Ph) in BFEE. PPh films obtained from BFEE-based electrolytes showed good electrochemical behavior, good thermal stability with electrical conductivity of 2.2×10-3 S cm-1, indicating that BFEE was a better medium for the electrosyntheses of PPh films. Dedoped PPh films were soluble in CH2Cl2, DMF and DMSO. The structure and morphology of the polymer were also characterized by UV-vis spectroscopy, FT-IR spectroscopy,1H NMR spectroscopy, and scanning electron microscopy, respectively, which indicated the polymerization occurrs mainly at C2 and C7 positions. Fluorescent spectral studies indicate that PPh is a good blue-light emitter.