Electronic texture of the thermoelectric oxide Na0.75CoO2

From 59Co and 23Na NMR, we demonstrate the impact of the Na+ vacancy ordering on the cobalt electronic states in Na0.75CoO2: at long time scales, there is neither a disproportionation into 75% Co3+ and 25% Co4+ states, nor a mixed-valence metal with a uniform Co3.25+ state. Instead, the system adopts an intermediate configuration in which 30% of the lattice sites form an ordered pattern of localized Co3+ states. Above 180 K, an anomalous mobility of specific Na+ sites is found to coexist with this electronic texture, suggesting that the formation of the latter may contribute to stabilizing the Na+ ordering. Control of the ion doping in these materials thus appears to be crucial for fine-tuning of their thermoelectric properties.     

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

Quinones undergo a one-step two-electron reduction in molten acetamide at the mercury and platinum electrodes. The reversibility of reduction increases in the order benzoquinone < napthaquinone = phenanthrquinone < anthraquinone.     

A new non-cubic equation of state

A new non-cubic equation of state is presented in this work. This expression is obtained from the original Redlich—Kwong equation of state by assuming that the attraction parameter depends not only on temperature, but also on density. Vapour—liquid equilibria in the coexistence region and PVT properties for the liquid, gas and supercritical fluid phases are accurately calculated with four parameters per isotherm. The generalization of this equation by a corresponding states correlation enables it to be applied over wide ranges of temperature, pressure and hydrocarbon molecular weight.     

Synthese electrochimique de bipyrannylidenes une nouvelle voie d'acces a des systemes fortement donneurs

The electrochemical method is used in the easy synthesis of donating systems by means of the cathodic reduction of thiopyrones in the presence of alkyl halides.     

Binucleophiles formes par voie electrochimique : synthese d'heterocycles macrocycliques oxa et oxa-aza

The mixed electrolyses of organic substrates (leading readily to dianions with a nucleophilic character) and bifunctional electrophiles allow the electrochemical synthesis of macroheterocycles. The experimental conditions are presented.     

Electrochemical reduction of α-unsaturated carbonyl compounds: Part VI. Effect of electrogenerated bases in very weakly protic solvents

Unsaturated carbonyl compounds were reduced electrochemically in carefully dried aprotic solvents. In the absence of protonating impurities, the i—V curves could be modified due to the de-activation of a part of the substrate by the action of the electrogenerated bases. In DMF solutions, the electrogenerated base which is able to deprotonate the ketone is mainly the dianion and discrepancies occur with, classical polarograms, of this class of reactants as observed at the level of the second step. For more conjugated ketones, a very cathodic step is assumed to correspond to the reduction of the conjugated anion of the ketone but the instability of this anion (inducing polymerisation reactions) prevents the acquisition of careful analytical evidence.     

Ionic liquids and CE combination

This paper reviews and discusses the analytical combination of ionic liquids (IL) with CE. On the one hand, it shows CE as a powerful technique to separate impurities from IL as well as being capable to determine physical and chemical properties of IL. On the other hand, it also shows how IL are employed in CE separations to enhance resolution, peak efficiency and peak symmetry. Specifically, IL are used as additives in CZE, NACE, and MEKC and as support coatings of the capillary wall in electrochromatography. The integrity of the IL in the electrophoretic system as well as the roles of the cations and anions of the IL in the electrophoretic separation are also discussed.