Synthesis, structural determination and antimicrobial evaluation of two novel CoII and ZnII halogenometallates as efficient catalysts for the acetalization reaction of aldehydes

Background: Complexes of imidazole derivatives with transition metal ions have attracted much attention because of their biological and pharmacological activities, such as antimicrobial, antifungal, antiallergic, antitumoural and antimetastatic properties. In addition, imidazoles occupy an important place owing to their meaningful catalytic activity in several processes, such as in hydroamination, hydrosilylation, Heck reaction and Henry reaction. In this work, we describe the crystallization of two halogenometallate based on 2-methylimidazole. Their IR, thermal analysis, catalytic properties and antibacterial activities have also been investigated. Results: Two new isostructural organic-inorganic hybrid materials, based on 2-methyl-1H-imidazole, 1 and 2, were synthesized and fully structurally characterized. The analysis of their crystal packing reveals non-covalent interactions, including C/N–HCl hydrogen bonds and stacking interactions, to be the main factor governing the supramolecular assembly of the crystalline complexes. The thermal decomposition of the complexes is a mono-stage process, confirmed by the three-dimensional representation of the powder diffraction patterns (TDXD). The catalytic structure exhibited promising activity using MeOH as solvent and as the unique source of acetalization. Moreover, the antimicrobial results suggested that metal-complexes exhibit significant antimicrobial activity. Conclusion: This study highlights again the structural and the biological diversities within the field of inorganic–organic hybrids. [Figure not available: see fulltext.]

Face or building superiority in peripheral vision reversed by task requirements

Peripheral vision has been the topic of few studies compared with central vision. Nevertheless, given that visual information covers all the visual field and that relevant information can originate from highly eccentric positions, the understanding of peripheral vision abilities for object perception seems essential. The poorer resolution of peripheral vision would first suggest that objects requiring large-scale feature integration such as buildings would be better processed than objects requiring finer analysis such as faces. Nevertheless, task requirements also determine the information (coarse or fine) necessary for a given object to be processed. We therefore investigated how task and eccentricity modulate object processing in peripheral vision. Three experiments were carried out requiring finer or coarser information processing of faces and buildings presented in central and peripheral vision. Our results showed that buildings were better judged as identical or familiar in periphery whilst faces were better categorised. We conclude that this superiority for a given stimulus in peripheral vision results (a) from the available information, which depends on the decrease of resolution with eccentricity, and (b) from the useful information, which depends on both the task and the semantic category

Etude du Comportement des Ondes Ultrasonores dans l'Os Trabéculaire

National audienceLes techniques de mesures quantitatives par ultrasons sont non-destructives et à ce titre sont intéressantes pour déterminer les caractéristiques mécaniques et/ou géométriques de l'os in vivo ou in vitro. La mesure est basée sur l'estimation de vitesses et d'atténuations des ondes qui se sont propagées dans le tissu osseux. Cependant, l'interprétation des résultats est difficile du fait de la complexité de ce tissu lequel est élastique, poreux, anisotrope et hétérogène. Par exemple, en utilisant la technique de transmission transverse in vitro, des études théoriques et expérimentales ont montré que le comportement des ondes dans l'os spongieux, aussi appelé trabéculaire, dépend fortement de l'angle entre la direction d'émission des ondes et l'orientation des trabécules lesquelles constituent la microstructure de ce tissu. Les études réalisées in vitro sur l'os trabéculaire supposent que l'échantillon osseux est un matériau orthotrope dont les axes principaux sont définis par l'orientation des trabécules. Le comportement des ondes transmises à travers l'échantillon est différent selon que les signaux émis sont dans la direction (1) parallèle ou (2) perpendiculaire à la direction principale d'alignement des trabécules. En pratique, les échantillons d'os sont alors coupés suivant ces axes et les mesures sont réalisées pour chaque direction principale. Cependant, il est difficile en pratique de déterminer correctement ces axes et les directions d'émission des ondes peuvent ne pas être parfaitement alignées avec les axes principaux du matériau. Dans ce travail nous étudions les effets de ces erreurs d'alignement sur les caractéristiques des ondes. Pour cela, nous développons un modèle ainsi que son implémentation numérique à l'aide d'une méthode aux éléments finis pour étudier la propagation des ondes transitoires. Ce modèle constitue un système couplé d'un milieu poreux élastique anisotrope saturé (dont le comportement est décrit par le modèle de Biot) immergé dans un fluide acoustique

Investigations on (C6H9N2)2[MIIBr4] halogenometallate complexes with MII = Co, Cu and Zn: Crystal structure, thermal behavior and magnetic properties

International audienceThree complexes with the general formula (C6H9N2)2[MIIBr4] with MII = Cu (1), Co (2) and Zn (3) have been grown by the slow evaporation method at room temperature. These compounds were subjected to the following characterization techniques: single crystal X-ray diffraction, thermal analysis (ATG-TD), In situ X-ray powder diffraction and temperature dependent magnetic susceptibility measurements. The crystals of (C6H9N2)2[CuBr4] belong to the triclinic P1¯ space group, whereas (C6H9N2)2[CoBr4] and (C6H9N2)2[ZnBr4] crystallize in the orthorhombic system with the Pbcn space group. Molecular structures of the three coordination compounds consist of [MBr4]2- anions and 2-amino-6-methylpyridinium cations linked together via non-covalent interactions including hydrogen bonding, π···π stacking and halogen···halogen interactions which lead to three-dimensional supramolecular architecture. The thermal decomposition of the copper compound reveals the slow crystallization of CuBr at 130 °C. Both compounds 1 and 2 exhibit weak antiferromagnetic interactions. © 2017 Elsevier B.V

Crystal architecture and thermal decomposition of two new organically templated cadmium sulfates

International audienceTwo organic-inorganic hybrid compounds (C5H14N2)[Cd(H2O)6](SO4)2 (I) and R-(C5H14N2)×[Cd(H2O)6](SO4)2 (II) are synthesized by the slow evaporation method and characterized by single crystal X-ray diffraction, thermogravimetry, temperature-dependent X-ray diffraction, and infrared spectroscopy. The first compound crystallizes in the centrosymmetric space group P21/n with the following unit cell parameters: a = 6.6208(2) Å, b = 10.6963(3) Å, c = 12.9318(4) Å, V = 893.05(6) Å3, and Z = 2. Its structure is solved by direct methods and refined by the least-squares analysis [R 1 = 0.0389 and wR 2 = 0.0821]. This compound shows a crystallographic disorder II destroys the inversion symmetry and leads to a fully ordered structure. Indeed, compound II crystallizes in the non-centrosymmetric space group P21 with the following unit cell parameters: a = 6.6306(1) Å, b = 10.7059(2) Å, c = 12.9186(1) Å, V = 894.67(2) Å3, and Z = 2. The crystal structure of both compounds is built from isolated SO 4 2− anions, disordered 2-methylpiperazinediium, (C5H14N2)2+ in compound I or R-2-methylpiperazinediium R-(C5H14N2)2+ in compound II, and divalent metal cations surrounded by six water molecules. These different entities are connected together only by a 3D hydrogen bond network. The thermodiffractometry and the thermogravimetric analyses indicate that the decomposition of the supramolecular precursors proceeds through several stages leading to cadmuim oxide

Zn2+ and Cu2+ doping of one-dimensional lead-free hybrid perovskite ABX3 for white light emission and green solar cell applications

International audienceThe one-dimensional ABX3 hybrid perovskite (A=(CH3)2NH2=DMA, B=Cd and X=Cl) was synthesized and structurally characterized. The optical analysis showed that the material has a direct band-gap nature with a gap energy of 5.36 eV. The obtained compound exhibited a “cold” white-light emission under an excitation wavelength of 240 nm with a color-rendering index up to 92 and a correlated color temperature (CCT) of 7582 K. The doping of the crystal with Cu2+ ions decreased the gap energy toward 2.51 eV. The partial substitution of the Cd atoms with Cu atoms decreased the intensity of the emitted white-light under 240 nm and led to a “cold” white-light emission with a CCT of 7117 K. The doping of the material with Zn2+ yielded a blue-shift and the emitted light revealed a CCT of 11,028 K. On the other hand, by incorporating Cu2+ions into the B site a broad absorption band is observed in the visible region resulting from the d-d transitions around the copper atoms which makes the material a good visible-light absorber. Hence, the Cu doped compound could be suitable for both white-light emission and photovoltaic solar cells

Copper(II) complexes with an arylhydrazone of methyl 2-cyanoacetate as effective catalysts in the microwave-assisted oxidation of cyclohexane

Reaction of sodium (E/Z)-2-(2-(1-cyano-2-methoxy-2-oxoethylidene)hydrazinyl)benzene-sulfonate (NaHL) with copper(II) nitrate hydrate in the presence of imidazole (im) in methanol affords [CuL(im)(H2O)] (1). Complex 1 is characterized by IR spectroscopy and ESI-MS spectrometry, elemental and single crystal X-ray crystal structural analyses. The coordination environment of the central copper(II) is nearly intermediate between ideal square-based pyramidal and trigonal bipyramidal geometry, three sites being occupied by the L2− ligand, which chelates in the O, N, O fashion, while two other sites are filled with the water and imidazole molecules. Extensive intermolecular hydrogen bonds between the L2−, water and imidazole ligands lead to a 3D supramolecular network. 1 and known Cu(II) complexes [Cu(H2O)2L]·H2O (2), [Cu(H2O)(py)L]·H2O (3) and [Cu3(µ3-OH)(NO3)(CH3OH)(µ2-X)3(µ2-HL)] (4) act as effective catalysts in the oxidation of cyclohexane to cyclohexanol and cyclohexanone, using low power microwave (MW) irradiation, under mild conditions. Without a promoter, the activity of the catalyst reached a turnover number of 1.44 × 103 and a turnover frequency of 1.98 × 103 h−1, after 2 h, at 50 °C. © 2017 Elsevier B.V

Food, nutrition and health in the Mediterranean

Folder : Rethinking the Mediterranean diet for the 21st century, Cosimo Lacirignola and Roberto Capona (CIHEAM-MAI, Bari).Existing and emerging malnutrition problems in the Mediterranean Region, Jean-Jacques Denis and Nouzha Guessous (IEM2S).Tackling child malnutrition in Egypt, Habiba Hassan-Wassef (Independent expert, Egypt).New food policies in the Mediterranean Region, Martine PADILLA (CIHEAM-MAI, Montpellier).Interview Paolo Maria Tafuri (Danone Djurdjura, Algeria).International audienc