Evaluation of the anti-oxidant properties of a SOD-mimic Mn-complex in activated macrophages

SOD-mimics are small complexes that reproduce the activity of superoxide dismutases, natural proteins that catalytically dismutate the superoxide anion. Activated macrophages, which produce ROS and RNS fluxes, constitute a relevant model to challenge antioxidant activity in a cellular context and were used to test a Mn-complex which was shown to efficiently alter the flow of O(2)(-), ONOO(-) and H(2)O(2).     

Microwaves-assisted solvent-free synthesis of N-acetamides by amidation or aminolysis

The preparation of acetamides directly from amines and an acetyl donor under microwaves without any catalyst is described. The inexpensive, solvent free, and fast reaction conditions are the important features of this procedure.     

A Landau-Zener Formula for Non-Degenerated Involutive Codimension 3 Crossings

In this paper, we study 2 x 2 systems of semi-classical pseudo-differential evolution equations which display eigenvalue crossing. We assume that the classical trajectories which hit the crossing set form the union of two involutive manifolds, with some non-degeneracy hypothesis, which covers the case of the Schrödinger equation with a matrix potential displaying a generic codimension 3 crossing. We derive an explicit formula for the energy transfer induced by the crossing, using two-scale Wigner measures. The proof is based on a normal form theorem which reduces the problem to an operator-valued Landau-Zener formula. Résumé. Cet article est consacré à létude dun système de deux équations dévolution pseudo-différentielles semi-classiques présentant un croisement de modes. Nous supposons que lensemble des trajectoires classiques qui rencontrent le croisement est lunion de deux sous-variétés involutives vérifiant une hypothèse de non-dégénérescence; cette situation contient le cas de léquation de Schrödinger avec un potentiel matriciel présentant un croisement générique de codimension 3. Nous obtenons une formule explicite décrivant le transfert dénergie au-dessus du croisement, à laide des mesures de Wigner à deux échelles. La démonstration repose sur un théorème de forme normale qui permet de se ramener à une formule de Landau-Zener à valeurs opérateurs. Communicated by Bernard Helffer submitted 16/09/02, accepted: 11/03/03     

Stability of divalent europium in an ionic liquid: spectroscopic investigations in 1-methyl-3-butylimidazolium hexafluorophosphate

In this work, devoted to 1-methyl-3-butylimidazolium hexafluorophosphate ionic liquid (BumimPF(6)), the importance of the purity of the solvent for spectroscopic investigations is highlighted. Results from small angle X-ray scattering indicate that the pure solvent exhibits a local organization. Europium(II), which appears to be unusually stable in BumimPF(6), is characterized by spectroscopic techniques (absorption, luminescence). Solvation of Eu(II) in BumimPF(6) and complexation effects in the presence of the crown ether 15C5 solubilized in the ionic liquid are discussed.     

Structural Studies of Crystalline Pentacalent Organobismuth Compounds

The syntheses and X-Ray analyses of three pentavalent organobismuth compounds are described; one of these compounds has a novel diphenylbis(trifluoroacetato)-bismuthate anion with trigonal bipyramidal geometry and a stereochemically active lone pair. Analysis of these structures together with other data from the literature allows a mapping of the reaction coordinate for bismuth polyhedra.     

Crotonates as dienophiles in high pressure-induced diels-alder cycloadditions: compared intra and intermolecular situations

The cyclization reactions of trienes 1 and 2 related intermolecular systems (5+6) and (9+10) have been investigated.     

Natural frequencies and axial response of a spinning liquid layer in a micro-gravity field

The natural frequencies of a solidly rotating liquid layer around a center-core, which under the action of an axial gravity changes to an amphora-type geometry, are determined. The liquid is frictionless and incompressible. According to the rotational Webernumber and the axial Bondnumber we have to distinguish natural frequencies for different modes. In additional the response of the free liquid surface to axial excitation has been obtained.

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Zusammenfassung Es werden Eigenfrequenzen einer rotierenden Flüssigkeitsschicht bestimmt, die sich unter dem Einfluß eines axialen Gravitationsfeldes zu einer Amphora-Geometrie verändert. Die Flüssigkeit ist reibungsfrei und inkompressibel. In Abhängigkeit von Weber- und Bondzahl zeigen sich unterschiedliche Eigenfrequenzen für verschiedene Moden. Zusätzlich wird das Antwortverhalten der freien Flüssigkeitsoberfläche auf axiale Anregung untersucht.

     

Synthesis and X-ray structure of the MnIICl2 and MnIIIF2 complexes of N,N'-dimethyl-2,11-diaza[3,3](2,6)pyridinophane. High-field electron paramagnetic resonance and density functional theory studies of the MnIII complex. Evidence for a low-lying spin triplet state

Two manganese complexes, (py2(NMe)2)MnIICl2 (1) and [(py2(NMe)2)MnIIIF2]+ (2), are here described with the macrocyclic ligand py2(NMe)2 (py2(NMe)2 = N,N'-dimethyl-2,11-diaza[3,3](2,6)pyridinophane). For both, the crystal structure is reported. The UV-visible spectrum of 2 exhibits a very broad near-infrared (NIR) band corresponding to the transition between the two e(g)-type orbitals split by the Jahn-Teller effect. A negative D value of ca. -4 cm(-1) was estimated by high-field and high-frequency electron paramagnetic resonance (HF-EPR) spectroscopy, which was consistent with symmetry considerations. Density functional theory (DFT) calculations on 2 support the 5B1 electronic ground state predicted from the X-ray structure. Moreover, to explain the large value of the D parameter, a spin triplet first excited spin state was postulated to occur at low energy. This was confirmed by the DFT calculations.     

Excess properties of binary alkanol-ether mixtures and the application of the ERAS model

Experimental results are reported of excess molar volumes V^E and excess molar enthalpies H^E for binary mixtures of 1-propanol, 2-propanol, 1-butanol and 2-butanol with diisopropyl ether (DIPE) and dibutyl ether (DBE) at 298.15 K. A vibrating-tube densitometer was used to determine V^E, and H^E was measured using a quasi-isothermal flow calorimeter. The applicability of the ERAS model has been investigated for describing the experimental data as well as literature data of alkanol-ether mixtures containing DBE or dipropyl ether (DPE).