Jacques Simonet

Electroactive polymers containing crown ether or polyether ligands as cation-responsive materials

Abstract The functionalization of electroactive polymers (electroconducting conjugated and redox-type polymers) by monocyclic and acyclic polyether groups is reviewed. In general, materials were chemically or electrochemically deposited as a film onto electrode surfaces from the oxidation of the substituted monomers. The ability of such structures for complexing cations could be evidenced from the modification of their electrochemical and optical properties. In the class of the conjugated polymers, functionalized polythiophenes and polyphenylenes led to numerous representative examples showing they were suited for the building of cation-responsive electrodes. Accordingly, some of these polymers were successfully used for the recognition and the extraction of a large variety of cations including alkali, heavy and precious metal cations. Different strategies were developed not only to enhance the affinity between the ligand and the cation, but also to obtain chemically reversible and selective ionic sensors.

New Boronic-Acid- and Boronate-Substituted Aromatic Compounds as Precursors of Fluoride-Responsive Conjugated Polymer Films

New electropolymerizable aromatic compounds (i.e. pyrrole, thiophene, aniline) bearing boronic acid and ester substituents have been synthesized and their electrochemical behavior has been investigated. Functionalized polythiophene and polypyrrole films could be anodically generated in acetonitrile, whereas the polyaniline derivative was electroformed in an acidic aqueous solution. The electrochemical responses of some of these materials were changed when fluoride ions were added to the electrolytic solutions. The strongest modifications, caused by binding of fluoride by the immobilized boron, were observed for the polypyrrole derivative in hydroorganic media.

Electrochemical and spectroscopic characterization of anodically formed nickel salen polymer films on glassy carbon, platinum, and optically transparent tin oxide electrodes in acetonitrile containing tetramethylammonium tetrafluoroborate

Anodically polymerized films of nickel salen formed on glassy carbon, optically transparent tin oxide, and platinum electrodes in acetonitrile containing tetramethylammonium tetrafluoroborate have been examined by means of cyclic voltammetry, thin-layer voltammetry, spectroelectrochemistry, and scanning electron microscopy. With the aid of thin-layer voltammetry, it has been confirmed that the global oxidative polymerization of nickel(II) salen involves three electrons per monomer. Polymerization proceeds through two distinct phases, the formation of which depend on the potential. Once the polymer film has been formed, the anodic process consists of the reversible one-electron nickel(III)/nickel(II) redox couple. Cyclic voltammetry along with spectroelectrochemistry has been employed to probe the roles of the nickel(III)/nickel(II) and nickel(II)/nickel(I) redox couples in the electrochemical response of the polymer film as well as the interconversion of the different oxidation states of nickel.

The anodic oxidation and polymerization of carbazoles and dicarbazoles N-substituted by polyether chains

The electrochemical oxidation of title compounds (I and II) may yield dimers or polymers according to the effective experimental conditions. The structure of dimers (coupling at the 3 position of each carbazyl unit) was fully confirmed by comparison with chemically prepared samples. Polymerization may also occur anodically. Especially with dicarbazoles (II), redox polymers were obtained. Active centers were identified as being dimer units included in the polymer matrix. Product analysis was based upon voltammetric and spectroelectrochemical data of dimers and polymers.

The anodic oxidation of fluorene and some of its derivatives: conditions for the formation of a new conducting polymer

Introduction (avant ou apres polymerisation) de groupes redox qui peuvent posseder des proprietes specifiques chimiques et electrochimiques

Electrochemical behaviour of different binaphthalene crown ethers. New electroformed polymer films as potential macromolecular hosts

Abstract The oxidation of bis-binaphtho-22-crown-6 (1) and binaphtho-20-crown-6 (2) in CH 2 Cl 2 containing Bu 4 NBF 4 leads to the one-step deposition of an electroactive polymer film onto the electrode surface. In other electrolytic media, the oxidation of these compounds causes the passivation of the electrode or leads reversibly to stable species. The potentiodynamic analysis of poly( 1 ) and poly ( 2 ) shows that these polymers are sensitive to the used potential scan range, in particular a degradation of their electroactivity is evidenced for too positive potential values. The UV-Vis and IR spectroscopic properties of electroformed poly ( 1 ) and poly ( 2 ) films are also investigated. In order to determine the linkage of the naphthalene groups within the polymer structure, the voltammetric study of two non-electropolymerizable derivatives is undertaken. From the obtained results, a structure of poly ( 1 ) is then proposed.

Electrochemical sensing of fluoride and sugars with a boronic acid-substituted bipyridine Fe(II) complex in solution and attached onto an electrode surface

Abstract The electrochemical behaviour of a boronic acid-substituted 2,2′-bipyridine 1 Fe(II) complex ([Fe(II) 1 3 ] 2+ ) has been investigated in aqueous buffered solutions, in the absence and in the presence of F − or various sugars as guest species. The binding of the halide to the boron atom led to a shift of the Fe(II)/Fe(III) oxidation peak towards less positive potentials whereas the sugars, and particularly d -fructose, had an opposite effect. With the aim of developing electrochemical sensors, the immobilization of this redox-active receptor onto an electrode surface has been successfully achieved from an electropolymerizable organometallic assembly consisting of the ligand 1 and a N -substituted pyrrole derivative. Its anodic oxidation yielded polymer films which exhibited stable electroactive properties in CH 3 CN. Owing to the total loss of their electroactivity in aqueous media, only the effect of F − on the response of the immobilized Fe(II)/Fe(III) system has been examined in CH 3 CN. An unusual complexation-induced catalytic phenomenon was evidenced in the presence of this guest anion.

Novel method for grafting alkyl chains onto glassy carbon. Application to the easy immobilization of ferrocene used as redox probe.

Primary alkyl iodides (RI) have been found to react with a cathodically charged glassy carbon surface at potentials more negative than -1.7 V vs Ag/AgCl. In aprotic solvents, this reaction results in grafting of the alkyl chains onto carbon. It is proposed that the process corresponds to the cathodic charge of graphitized and fullerenized zones present in carbon followed by a displacement reaction (analogous to a nucleophilic attack) toward alkyl iodides. This new mode of grafting is applied to the immobilization of ferrocene used as an electrochemical probe. The present work points out the reaction of ω-iodoalkylferrocenes and quantifies the level of grafting of alkyl chains via this promising method for modification of carbon surfaces. Coverage levels were found to be high, reaching the apparent surface concentrations of 8 × 10(-9) mol cm(-2). These large values are explained on the basis of swelling of the interface provoked by progressive charging of the carbon surface via insertion of tetraalkylammonium cations concomitantly with the substitution process. Alkylferrocene layers deposited onto carbon were found to be chemically and electrochemically stable.

The anodic trimerization of aromatic orthodiethers: new developments

Abstract While the anodic trimerization of veratrole (leading to hexamethoxytriphenylene) is now a very well known reaction, developments concerning either mixed electrolysis (mixture of two orthodiethers) and/or oxidation of dissymmetrical substrates have not been conducted go far. The presented method, often specific, allows the synthesis of a new palette of liquid crystal precursors.

A stable carbene as π-acceptor electrochemical reduction to the radical anion

Abstract The electrochemical reduction of the carbene 1 reversibly yielded the corresponding radical anion 2 , which was characterized by ESR measurements. Ab initio calculations provided a better understanding of its structure and stability.