Deprotometalation-iodolysis and computed CH acidity of 1,2,3- and 1,2,4-triazoles. Application to the synthesis of resveratrol analogues

International audience1-Aryl- and 2-aryl-1,2,3-triazoles were synthesized by N-arylation of the corresponding azoles using aryl iodides. The deprotometalations of 1-phenyl-1,2,3-triazole and -1,2,4-triazole were performed using a 2,2,6,6-tetramethylpiperidino-based mixed lithium-zinc combination and occurred at the most acidic site, affording by iodolysis the 5-substituted derivatives. Dideprotonation was noted from 1-(2-thienyl)-1,2,4-triazole by increasing the amount of base. From 2-phenyl-1,2,3-triazoles, and in particular from 2-(4-trifluoromethoxy)phenyl-1,2,3-triazole, reactions at the 4 position of the triazolyl, but also ortho to the triazolyl on the phenyl group, were observed. The results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method. 4-Iodo-2-phenyl-1,2,3-triazole and 4-iodo-2-(2-iodophenyl)-1,2,3-triazole were next involved in Suzuki coupling reactions to furnish the corresponding 4-arylated and 4,2’-diarylated derivatives. When evaluated for biological activities, the latter (which are resveratrol analogues) showed moderate antibacterial activity and promising antiproliferative effect against MDA-MB-231 cell line

Sulfur isotope evolution in sulfide ores from Western Alps: Assessing the influence of subduction-related metamorphism

Sulfides entering subduction zones can play an important role in the release of sulfur and metals to the mantle wedge and contribute to the formation of volcanic arc-associated ores. Fractionation of stable sulfur isotopes recorded by sulfides during metamorphism can provide evidence of fluid-rock interactions during metamorphism and give insights on sulfur mobilization. A detailed microtextural and geochemical study was performed on mineralized samples from two ocean floor-related sulfide deposits (Servette and Beth-Ghinivert) in high-pressure units of the Italian Western Alps, which underwent different metamorphic evolutions. The combination of microtextural investigations with d34S values from in situ ion probe analyses within individual pyrite and chalcopyrite grains allowed evaluation of the effectiveness of metamorphism in modifying the isotopic record and mobilizing sulfur and metals and have insights on fluid circulation within the slab. Textures and isotopic compositions inherited from the protolith are recorded at Beth-Ghinivert, where limited metamorphic recrystallization is attributed to limited interaction with metamorphic fluids. Isotopic modification by metamorphic processes occurred only at the submillimeter scale at Servette, where local interactions with infiltrating hydrothermal fluid are recorded by metamorphic grains. Notwithstanding the differences recorded by the two deposits, neither underwent intensive isotopic reequilibration or records evidence of intense fluid-rock interaction and S mobilization during metamorphism. Therefore, subducted sulfide deposits dominated by pyrite and chalcopyrite are unlikely to release significant quantities of sulfur to the mantle wedge and to arc magmatism sources at metamorphic grades below the lower eclogite facies

Gestion des crises lors du dépassement des seuils de traitabilité des filières biologiques : cas de l'ammonium à Choisy-le-Roi

Les usines du Syndicat des Eaux d'Ile-de-France tendent à reproduire en les accélérant les cycles biologiques les plus importants de l'auto épuration. Les gains qui résultent de cette application sont évidents : la suppression de la chloration de l'eau brute a permis la réduction à son niveau le plus bas de la production de composés organochlorés sapides et dangereux ; l'utilisation étagée de l'ozone et le couplage avec la filtration sur charbon actif granulé ont abaissé la valeur du paramètre carbone organique et notamment de la fraction assimilable ultérieurement dans le réseau ce qui conduit à une grande stabilité du résiduel bactériostatique : le seuil de saveur a été très significativement réduit. En revanche la biologie s'accomode mal de variations brutales de la qualité de l'eau brute et les seuils de traitabilité sont variables en fonction de paramètres multiples. Concernant la nitrification, sa mise en place à Choisy a été à l'origine d'une évolution profonde des modalités de l'exploitation. Pour éviter un retour à la chloration finale génératrice de saveurs, le fonctionnement de la filière doit être suivi de très près. Un système expert et un réseau d'alerte rendent possible l'anticipation de toute décision telle que le ralentissement de la vitesse de filtration et l'utilisation des secours. Un effort particulier doit être mené en parallèle pour contrôler en permanence la qualité de la ressource et l'utilisation optimale des dispositifs d'épuration

Magnetic Interactions In YbBa2_{\bf 2}Cu3_{\bf 3}Ox_{\bf x} (x = 7.0, 6.0) From 170^{\bf 170}Yb3+^{\bf 3+} Mössbauer Measurements

The magnetic interactions in superconducting YbBa$_2$Cu$_3$O$_7$ and non-superconducting YbBa$_2$Cu$_3$O$_6$ have been examined using $^{170}$Yb$^{3+}$ Mössbauer spectroscopy on grain-oriented samples. In YbBa$_2$Cu$_3$O$_7$ where the Yb$^{3+}$ sublattice orders at 0.35 K and the saturated magnetic moment is 1.75 $\mu_{\rm B}$, the saturated molecular field is 0.4 T and it is directed perpendicular to the $c$-axis. In YbBa$_2$Cu$_3$O$_6$, where the Cu(2) sublattice also orders, the average saturated molecular field on Yb$^{3+}$ is 0.2 T. It is disordered in direction and contains contributions from both the Yb$^{3+}$ and the Cu(2)$^{2+}$ sublattices. The presence of a Cu(2)$^{2+}$ derived molecular field shows the Yb$^{3+}$ ions are not at a center of magnetic inversion symmetry relative to the ordered Cu(2)$^{2+}$ moments