Alain Louati

New ionic liquid crystals based on imidazolium salts

The new ionic liquid crystal 1-(4-dodecyloxybenzyl)-3-methyl-1H-imidazol-3-ium bromide has been synthesized and its X-ray structure obtained; various salts containing BF4−, SCN−, PF6−, CF3SO3−, (CF3SO2)2N− have been prepared by anion metathesis in water from bromide species as starting materials, and finally, the mesomorphism and electrochemical behavior have been investigated.

A convenient method for preparing rigid-core ionic liquid crystals

Summary An efficient, solvent free method for the N-arylation of imidazole by 1-(dodecyloxy)-4-iodobenzene using Cu(II)-NaY as catalyst and K2CO3 as base is reported. By this synthetic approach, mesomorphic 3-[4-(dodecyloxy)phenyl]-1-methyl-1H-imidazol-3-ium iodide was synthesized in a two-step procedure, and its mesomorphism has been fully investigated by polarised optical microscopy, differential scanning calorimetry and X-ray diffraction. In addition its lamellar crystal structure, electrochemical behaviour and UV (absorption and emission) properties are reported.

First synthesis of a '1,2-diquinone-calix[4]arene'. Interaction of its reduced form with Ag+

Abstract Electrochemical oxidation of 5,11,17,23-tetra- tert -butyl-25,26-bis(diphenylphosphinoylmethoxy)-27,28-dihydroxycalix[4]arene ( 3 ), a calixarene with two phosphoryl units appended on proximal positions, affords the corresponding ‘1,2-diquinone-calix[4]arene’ ( 4 ). The formation of 4 results from nucleophilic attack of residual water on anodically generated diphenoxylium cations. Preliminary voltammetric experiments in CH 3 CN on a platinum electrode showed that 4 is suitable for electrochemical detection of the silver metal cation.

Anodic oxidation of p-But-calix[4]arene-(OH)2-(OCH2CONEt2)2. Electrogeneration of a calixdiquinone in dichloromethane

The electrochemical oxidation of p-But-calix[4]arene-(OH)2-(OCH2CONEt2)2 1 has been investigated for the first time and was shown to result in the formation of the corresponding diquinone 3. The reaction proceeds via two successive two-electron irreversible oxidation steps both governed by an ECE mechanism. Alkali cations recognition can be realized by exhaustive oxidation of 1 in the presence of alkali salts.

Electrochemical cyanation of porphyrins: Meso-mono to tetracyanoocta-ethylporphyrins

Abstract Electrochemical oxidation of Zn-octaethylporphyrin in the presence of CN − gave meso-mono-, di-(ab+ac), tri- and tetracyanooctaethylporphyrin with good selectivity and yields.

Capping Methodology in Cyclodextrin Chemistry: Use of a Symmetrical Diketone Reagent for Regiospecific Installation of Unsymmetrical Imine–Enamine and Imidazole Caps

Methylated α- and β-cyclodextrin skeletons were both equipped with an unsymmetrical N-(2-N-alkylaminoacenaphthenyl)alkylimine rigid handle. The capping reaction, which consists of condensing a diaminocyclodextrin with highly symmetrical acenaphthenequinone, was found to be regiospecific when starting from cyclodextrin-diamines without any symmetry element. All modified cyclooligosaccharides have intra-annular nitrogen donor atoms. They undergo further cyclization on oxidation, whether chemically with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone or electrochemically, to give highly strained cyclodextrins capped with an unsymmetrical 1,2-disubstituted 1H-imidazole unit.

In Situ FTIR Spectroelectrochemical Investigations on Cu2+-ZSM-5 Modified Electrodes. Reactivity of the Electrogenerated Species Towards NO in Aqueous Solution

In situ FTIR spectroelectrochemical experiments have been carried out on Cu2+-ZSM-5 with 40 and 100 % ion exchange level with Nafion films coated on glassy carbon electrodes, and on the application of these electrodes to the interaction of NO with the electrogenerated species in aqueous solution. Voltammetric results revealed that the reduction of Cu2+–exchanged zeolites proceeds by two successive quasireversible one-electron steps. The first electron gain resulted in the formation of Cu+-ZSM-5. Cathodic peak potential shifts observed in NO-saturated aqueous solution indicated electrogenerated Cu+-ZSM-5–NO interactions. FTIR measurements showed that the Cu+ ions in the electroreduced Cu2+-ZSM-5 form with NO, among others products, Cu+-ZSM-5-nitrosylic complexes.

Synthesis of N,N′-phenyleneporphyrines. Models for cytochrome P-450–1-aminobenzotriazole inactivation products

N,N′-Phenyleneporphyrins were prepared either by oxidative cyclisation of cobalt(II)-N-phenylporphyrins or by direct interaction of a cobalt(III)-porphyrin and 1-aminobenzotriazole in the presence of dioxygen.

Voltampérométrie et comportement rédox de métalloporphyrines inhabituelles

Abstract Tetraphenylporphyrin (TPP) compounds of rhenium-tricarbonyl have been investigated by pulse polarography, by cyclic voltammetry and by hydrodynamic voltammetry at Levichs rotated disk electrode. The metalloporphyrins HTPPRe(CO) 3 and TPP(Re(CO) 3 ) 2 exhibited several anodic and cathodic waves, which corresponded qualitatively to well-known one-electron transfer processes of the free base H 2 TPP. Quantitatively, however, the relevant electron affinities and redox reactivities of H 2 TPP where shifted appreciably by coordination with rhenium-tricarbonyl. The observed shifts in half-wave potentials and electrochemical kinetics are satisfactorily accounted for by charge distribution effects on the porphyrin moiety, induced by bonding between Re(CO) 3 and three of the four nitrogen atoms of the tetrapyrole ring.