C. Chevrot

Electropolymerization of 3,4-ethylenedioxythiophene and 3,4-ethylenedioxythiophene methanol in the presence of dodecylbenzenesulfonate

Abstract Electropolymerization of 3,4-ethylenedioxythiophene (EDT) and its hydroxymethyl derivative (EDTM) was carried out in sodium dodecylbenzenesulfonate aqueous solution by cyclic voltammetry and chronoamperometry on a platinum electrode. PEDTM seems to be irreversibly damaged at lower potentials than PEDT (+1.2 V/SCE versus +1.4 V/SCE, respectively). Moreover, scanning electronic microscopy (SEM) and surface profiling revealed a higher compaction for PEDTM films. Nevertheless, these films stopped growing for a charge of about 80 mC cm −2 as demonstrated by a UV-Vis spectrophotometric study.

Electrochemical behaviour of 3, 4-ethylenedioxythiophene functionalized by a sulphonate group. Application to the preparation of poly(3, 4-ethylenedioxythiophene) having permanent cation-exchange properties

We report the synthesis of a new 3,4-ethylenedioxythiophene monomer functionalized by a sulphonate group. Its electrochemical polymerization in water allows the generation of water-soluble oligomers. Furthermore the electrochemical polymerization of an equimolar aqueous solution of this new monomer and the unsubstituted one produces a polymer film having permanent cation-exchange properties. This phenomenon has been investigated with hexamine ruthenium(III) and uranyl cationic species using electrochemical and radiochemical methods.

Chain length effect on the electroactivity of poly(N-alkyl-3,6-carbazolediyl) thin films

Abstract Several poly(N-alkyl-3,6-carbazolediyl)s (PCZS) have been obtained by electroreduction of the corresponding dibromomonomers in the presence of a catalytic Ni(0)-based system. Depending on the nature of the alkyl group linked to the nitrogen atom, PCZS are soluble in organic solvents such as nitrobenzene, chloroform and tetrahydrofuran and insoluble in acetonitrile and alcohols. Taking these properties into account thin films have been prepared (in the neutral state) either by casting from solutions or directly by electrodeposition onto conducting substrates in the CH3CN/NBu4BF4 medium. Electrochemical behavior of these materials in the range 0–1.4 V versus saturated calomel electrode (SCE) is strongly dependent on the macromolecular chain length, but is slightly affected by the nature of the alkyl chain. Depending on the potential applied, the films are either colorless, green or blue. The redox processes involved in electrochemical oxidation of the polymer as well as those of the oligomers are discussed.

Electrosynthese catalytique d'acides benzoiques para-substitues a partir du derive halogene correspondant et de l'anhydride carbonique

Abstract Electrochemical reduction of the complex formed by insertion of an electrogenerated nickel(0) atom into the carbon—halogen bond of a p -halogeno-substituted aromatic compound in the presence of CO 2 leads to formation of the corresponding aromatic carboxylate. At room temperature the electrochemical synthesis needs catalytic quantities of nickel chloride coordinated to triphenylphosphine or 1,2-bis(diphenylphosphino)ethane.

Synthesis and characterization of poly (N-butyl-3,6-carbazolediyl)

SummaryPoly (N-butyl-3,6-carbazolediyl) was synthesized by electrochemcial reduction of the NiBr2, 2,2′bipyridine/3,6 dibromo N-butylcarbazole system in N,N dimethylacetamide. The favorable interactions between solvent and butyl groups lead to the solubilization of the electroactive polymer in organic medium and allowed the determination of macromolecular and structural features by means of classical methods. From 13C NMR investigations it was concluded to a Π conjugation centered on the nitrogen atom of the carbazolic structure.

Langmuir-Blodgett films of an alkoxy derivative of poly(3,4-ethylenedioxythiophene)

Abstract The amphiphilic character of a conducting polymer obtained by chemical polymerization of a C14 alkylated 3,4-ethylenedioxythiophene methanol monomer allowed the formation of a stable monolayer at the air-water interface. Several monolayers were transferred on a solid substrate and a lamellar well-organized structure was obtained. The doping was carried out in gas phase by NO2 and monitored by ultraviolet-visible spectroscopy and quartz crystal microbalance. The doped material showed a good conductivity as compared to other Langmuir-Blodgett films of conducting molecules.

Optical and electronic properties of undoped and doped poly(N-alkylcarbazole) thin layers

Optical and electrochemical properties of a cast film of poly(N-alkylcarbazole) (PCZ) obtained from an organic solution and of an electrodeposited thin layer on indium—tin oxide (ITO) glass are described. The electrochromic effect can then be quantified from a spectro-electrochemical study. Moreover, the chemical doping of PCZ solution with iron trichloride has been controlled by recording the evolution of the optical absorption spectrum. From such a solution, a thin layer of doped PCZ has been coated, characterized and its conductivity determined.

Investigation on the electrocatalyzed step polymerization of soluble electroactive poly(N-alkyl-3,6-carbazolylenes)

Abstract Simultaneous GPC and cyclic voltammetry (CV) measurements were carried out in the course of the electrocatalyzed polymerization of various 3,6-dibromo(N-alkylcarbazoles). The evolution of the molar mass population distribution as a function of the electrolysis time reveals a step polymerization processm while showing a termination of the chain growth due to the occurrence of monobrominated species. The consumption of the catalytic species corresponds in a first step to an increase in the chain length, while after given periods there is no more chain growth related to the continuous consumption of the catalytic precursor. The study of the effect of the initial [monomer]/[catalyst] ratio on the molar mass population evolution indicates that the coupling of Ni(0)-activated species is responsible for the chain growth.

Electrosynthesis and study of phenylene-carbazolylene copolymers

Abstract Phenylene-carbazolylene copolymers with variable composition and properties were prepared by electrocatalyzed dehalogenative polycondensation of 4,4′-dihalobiphenyl and N -alkyl-3,6-dibromocarbazole mixtures in the presence of a zero valent nickel catalyst. The polymers are partly soluble in polar solvents and this solubility depends on the proportion of carbazolylene units in the materials. For a given composition, solubility increases with length of the aliphatic substituent linked to the nitrogen. The conductivity upon doping varies between those of the corresponding homopolymers and is a function of the length of the alkyl substituents. Thin films of these materials can be prepared either by solvent casting or by direct electrodeposition onto various supports. The electrochemical behavior is strongly dependent on the copolymer composition and reveals the existence of two distinct electronic states (two quantum wells): the first one is related to the presence of the carbazolylene units, while the second shows the presence of phenylene moieties.

Characterization and properties of the charge transfer complex of carbazole derivatives

Abstract The purpose of this work is to characterize the charge transfer complex (CTC) formed between one carbazolic derivative and an organic electron acceptor, and to compare some physicochemical properties. We have used either poly (N-vinylcarbazole) or poly(N-butylcarbazole) or again 3,3′-diethyl-9,9′-dicarbazole (DEC) as a donor, and one of the following as acceptor: tetracyanoethylene (TCNE), 2,4,7-trinitro-9-fluorenone (TNF), 1,4-naphthoquinone (NQ) or 2,3-dicyano-1,4-naphthoquinone (DCNQ). The characterization of the CTC has been made following two methods: optical spectroscopy or differential scanning calorimetry (DSC). In fact, when the optical absorption of the CTC corresponds to a well-defined peak, its characterization by optical spectroscopy leads to the determination of some intrinsic properties such as equilibrium constant, molar extinction coefficient, etc. On the contrary, if the optical absorption is indiscernible of the absorption peaks of acceptor or donor alone, we have shown that use of DSC allows us to characterize the formation of CTC measuring the fusion enthalpy of the CTC. These determinations are only described, in this paper, in the case of the dimer DEC as a donor which possesses a well-defined melting point. The CTC between DEC and each acceptor has been characterized in this way.