Maxime Roche

Reaction of diarylnitrilimines with 3-arylidene-4-isothiochromanones. A general approach to the first thiadiazaphenanthrene

Abstract A general synthesis of derivatives of 1,2,4-triphenyl-4,10-dihydro-10-thia-3,4-diazaphenanthrene (a new heterocyclic skeleton) in two steps from 3-arylidene-4-isothiochromanones via cycloaddition route is recorded.

Functionalization of polypyrroles with acids and β-diketones as complexing groups. Part 1: electrochemical synthesis and properties

The synthesis of pyrroles functionalized by complexing groups such as acetylacetone, dibenzoylmethane or carboxylic acids is described, as well as their electrooxidation into functionalized polypyrroles. We have studied the behavior of poly(functionalized pyrrole) films in the presence of Li+, Ni2+ and Co2+ cations by cyclic voltammetry (CV) and infrared (IR) spectroscopy. The electrochemical response under various conditions differs with the nature of the complexing group. We have also demonstrated the possibility to electrochemically generate copolymers with pyrrole and each functionalized pyrrole. The proportion of functional groups in the copolymers was estimated by following the peak potential dependence in cyclic voltammetry and was confirmed by IR spectroscopy.

Functionalization of polypyrroles with acids and β-diketones as complexing groups. Part 2: electrochemical growth of polypyrrole into hybrid zirconium oxopolymer sol–gel coatings

New hybrid materials were prepared by a sol–gel route from zirconium propoxide and functionalized polypyrroles bearing a complexing group (carboxylic acid or β-diketone). Formation of polypyrroles in the gel deposited on an indium tin oxide (ITO) electrode was performed electrochemically in aqueous media. The optimal conditions for the preparation of stable sols were determined, as well as the deposition conditions to obtain reproducible transparent uniform coatings in which electropolymerization was possible. The xerogels as well as the composites after polymerization were analyzed with the help of optical microscopy (OM), scanning electron microscopy (SEM) and X-ray fluorescence. The electrochemical characteristics of the composites were investigated by cyclic voltammetry and their adherence evaluated. From the polymerization rate and simple assumptions, the rate constant for pyrrole polymerization inside the gels has been evaluated.

Electrochemical properties of some benzoxazines: conditions for electropolymerization in alkaline medium

Abstract The electro-oxidation of three isomeric methyl benzoxazines has been studied in acetonitrile and methanol in either neutral or alkaline media. Oxidation potentials have been determined and the reactivity of the benzoxazine cation radicals estimated. In alkaline methanol, the mechanism changes in favour of oxidation of the benzoxazine anion, and formation of a thin polymer layer is observed on metallic substrates. The resulting polymers were analysed by X-ray photoelectron spectroscopy measurements and a polymer formula has been proposed.

Electropolymerization of carboxylic acid functionalized pyrrole into hybrid zirconium–silicon oxopolymer sol–gel coatings

We describe the preparation of new hybrid materials using a novel method previously reported by us. These materials are constituted of an organic part and an inorganic network of silicon and zirconium oxopolymers. The organic polymer is obtained by electropolymerization of an N-functionalized pyrrole entrapped in the xerogel. The latter was obtained from a sol prepared by hydrolysis condensation of a mixture of alkoxysilanes, zirconium alkoxydes and the organic monomer. The chemical and electrochemical conditions to prepare these hybrid materials were investigated by varying the zirconium content, the presence and the nature of doping species in the xerogel, the nature of the electrolytic salt and the hydrolysis catalyst. From the results of cyclic voltammetry, optical microscopy, scanning electron microscopy and X-ray fluorescence, we show that the formation of a conducting polymer with good properties in the xerogel depends on the zirconium content and on both the nature and the presence of doping species in the xerogel, whereas the influence of the electrolytic salt is very limited.

Electrochemical oxidation of some enol silyl ethers; investigations on the reactivity of cyclizable cation-radicals

The electrochemical oxidation of several silyl enolethers (SE) formed from a variety of differently substituted α- or β-tetralones by side chains is described. The behaviour of the cation radicals of the SE has been found to be strongly dependent on the substituted lateral chain, especially when the substituent contains a cyclizable group like a double bond. The difference between the oxidation potentials has been attibuted to the occurence of a first order chemical reaction between the cation radical and the substituent, which is probably a cyclization reaction. The relative rates of this reaction have been discussed in relation to the substituent.