Anodic oxidation of dipyrrolyls linked with conjugated spacers: study of electronic interactions between the polypyrrole chain and the spacers (original) (raw)
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Journal of Electroanalytical Chemistry, 1998
Dipyrrolyl monomers with more or less flexible and bulky spacers have been synthesized. The electrochemical behaviour of these monomers and their corresponding polymers has been investigated. Convergent results, obtained by cyclic voltammetry of the monomers and the polymers, ESCA analysis and mass measurements, demonstrate that from an early stage of polymerization, the monomers are oxidized at both pyrrolyl units, leading to different polymer structures, depending on the spacers used.
Polymer, 2006
This work reports a theoretical investigation about the structural and electronic properties of polymers constituted by pyrrole and Nhydroxymethylpyrrole in both neutral and p-doped states. Ab initio quantum mechanical calculations were performed on neutral and positively charged oligomers to evaluate the bond length alternation pattern in the p-system, the molecular conformation, the p-p* transition energies and the ionization potential. Results, which have been extrapolated to infinite polymer chains, allow analyze the influence of N-hydroxyalkylation of polypyrrole on these properties.
Halomethylpyrroles as candidate monomers for conducting polymers: a theoretical study
Chemical Physics, 2004
Structural, electronic, thermochemical and electrical properties of mono-, di-and trihalomethylpyrroles (HMPys), NC 4 H 4-CH n X 3 À n ; X = F, Cl, Br; n = 0, 1, 2, 3, and their radical cations have been studied using DFT-B3LYP method with 6-31G(d,p) basis set. Vibrational frequencies and NMR shielding constants of these compounds have also been calculated and analyzed. HMPys are proposed in this research as candidate monomers for conducting polymers with modified characteristics compared to polypyrrole and polymethylpyrrole. Stability of HMPy radical cations have been studied in detail and compared with available experimental data, including oxidation potentials. Results of the present study show that bromomethylpyrroles have the highest thermochemical stability and have higher characteristics for electropolymerization compared to fluoro-and chloromethylpyrroles. Stability of HMPys increases with increasing number of substituted halogen atoms.
Probing Polymer–Pendant Interactions in the Conducting Redox Polymer Poly(pyrrol-3-ylhydroquinone)
The Journal of Physical Chemistry C, 2014
Conducting polymers with redox active pendant groups show properties typical of both conducting polymers (i.e., capacitive charging and intrinsic conductivity) and redox polymers (i.e., electrochemical surface response at the formal potential of the pendant groups). The two components can also exert significant interaction on each other during their separate electrochemical reactions. In poly(pyrrol-3-ylhydroquinone), a polypyrrole derivative functionalized with hydroquinone units, the redox conversion of the pendant groups has a large impact on the polymer backbone. This interaction is manifested by a loss of bipolaron states during the hydroquinone oxidation, leading to a decreasing pdoping level with increasing potential, something which, to the best of our knowledge, has never been observed for a conducting polymer. Another effect is a contraction of the polymer film, and subsequent mass loss due to solvent expulsion upon hydroquinone oxidation, which counteracts the normal swelling of polypyrrole with increased potential. The conducting redox polymer under investigation has been synthesized via two routes, leading to different fractions of subunits bearing redox active hydroquinone groups. While the redox potentials are unaffected by the synthesis route, the backbone/pendant group interaction varies notably depending on the degree of quinone functionalization. This type of polymers could find use in, e.g., organic energy storage materials, since the polymer backbone both increases the electronic conductivity and prevents dissolution of the active material, as well as in actuator application, due to polymer contraction over the relatively narrow potential region where the pendant group redox chemistry occurs.
Synthetic Metals, 2007
A series of 2,2 -dipyrrole monomers separated by aza-spacers (N,N -bis-(1H-pyrrol-2-ylmethylene)-benzene-1,4-diamine; N 4 ,N 4 -bis-(1H-pyrrol-2-ylmethylene)-biphenyl-4,4 -diamine; N,N -bis-[1-(1H-pyrrol-2-yl)-ethylidene]-hydrazine; and 4,4 -bis[(1H-pyrrol-2-yl)-diazenyl] biphenyl) have been synthesised using modified Schiff and azo-coupling reactions. The new 2,2 -dipyrroles linked with conjugated aza-spacers have been evaluated as precursors of narrow band gap conducting polymers. Electrochemically synthesized poly(N,N -bis-[1-(1H-pyrrol-2-yl)ethylidene]-hydrazine) displays a narrow band gap of just 0.7 eV, making it a suitable candidate for optoelectronic applications. (C. Pozo-Gonzalo), boris trofimov@irioch.irk.ru (B.A. Trofimov), zaitsev@organ.su.se (A.B. Zaitsev).
Electropolymerized multilayer and copolymeric structures based on substituted pyrroles
Journal of …, 1988
The preparation of thin polymeric films containing redox couples on carbon or platinum electrodes is described based on the oxidative ~~~o~lyrn~tion of substituted pyrroks. The redox couples involved are pyrrole derivatives of the chromophore [Ru(bpy),]" (bpy is 2,2'-bipyridine), the electron transfer acceptor paraquat (PQ'+ ): and the electron transfer donor phenothiazine. Copolymeric films containing more than one redox couple have been prepared as having film structures in which there are spatially segregated bi-and trilayers, each layer containing a different couple.
Electrochemical polymerization of some dihydrobenzodipyrroles
1989
Anodic coupling of the dihydrobenzodipyrrole isomer:< 1 H,8H-pyrrolo[3,2-g]indule (I) , I H,7H-pyrrolo[3,2-flindole (2). and 1 H,5H-pyrrolo[2,3.-f]indole (3) in 0,l 51 tetraelhylammonium perchlorate in acetunitrile produces polymeric films which are reversibly oxidiLed around 0,3 V vs. Ag/Ag+ with 0,5 electrons per monomeric unit. IR reflectance, UV-vis dnd cyclic voltammetry show t hat the oxidized polymers undergo easy overoxidation al the benmle ring without affecting the charge slurage ability. Conductivities (0,2 ~ 5 '. cm ~ ') A r e higher than those presented by chemically prepared samples-10-l Q-'. c m-') and are attributed 10 more ordered structures of the polymers.
Journal of Solid State Electrochemistry, 2013
Conducting poly(pyrrole-N-methylpyrrole) (P(Py-NMPy)) was electrochemically synthesized on a gold electrode in a lithium perchlorate-containing acetonitrile electrolyte solution and compared with polypyrrole (PPy) and poly(N-methylpyrrole) (PNMPy) prepared under the same conditions. The obtained polymers were characterized with cyclic voltammetry, in situ resistance measurements, in situ UV-vis spectroscopy, FTIR spectroscopy, and scanning electron microscopy. The onset potentials for pyrrole and N-methylpyrrole monomer oxidation differ by about 0.1 V. Nucleation processes initiated by the radical cations are followed by growth of nuclei into continuous films. The oxidation and reduction peaks for the P(Py-NMPy) copolymer synthesized at 1:1 M concentration ratio of the comonomers are between those of PPy and PNMPy. A decreased [Py]/[NMPy] comonomer concentration ratio yields in the copolymers shifts of peak potentials to more positive values. The in situ resistance of copolymers measured from −0.20 to 0.90 V vs. Ag/AgCl decreased with increasing [Py]/[NMPy] concentration ratio. In situ UV-vis and ex situ FTIR spectra of copolymers show spectroscopic behavior intermediate between those of the homopolymers. Scanning electron microscopy micrographs of the samples show fundamental differences between the morphology of the homo-and copolymers.
Pure and Applied Chemistry, 1997
The present paper describes some recent results concerning processable electroconducting materials prepared starting with properly substituted pyrrole derivatives. The first approach was based on the preparation of a precursor polymer by free radical polymerization of N-vinylpyrrole. This insulating, soluble and filmable polymer could be converted into an electroconducting product by intramolecular ladderization through oxidation of the pyrrole side chains. In the same frame the chemical homo and copolymerization of 3-decylpyrrole with pyrrole allowed to produce soluble or swellable polymers having conductivity variable with copolymer composition. The ladder formation and internal plastification by the long aliphatic side chain have been combined to give polymers derived from 3-decyl-N-vinylpyrrole and its copolymers with N-vinylpyrrole. Relationships between electroconductivity and controlled structure of the subject materials are discussed with reference to their blends with insulating plastomers.