Isotopomeric diols by “one-pot” Ru-catalyzed homogeneous hydrogenation of dicarboxylic acids

The “one-pot” homogeneous hydrogenation of γ-butyrolactone and succinic or fumaric acid to 1,4-butandiol, have been successfully realized in the presence of the catalytic system [Ru(acac)₃]/triphos] [triphos:MeC(CH₂PPh₂)₃]. The influence of some reaction parameters on the regioselectivity and the rate of the reaction were investigated. The study was then extended to the “one-pot” synthesis of isotopomeric 1,4-butandiols by deuteration of the appropriate substrates in a deuterated solvent. 1,4-butandiol-d₈, which was fully characterized, was obtained with 96% yield and 100% isotopomeric selectivity. A mechanism was proposed to rationalize the role of catalyst, solvent and deuterium distribution.     

d6 metal systems for white phosphorus activation

This short review describes a breakthrough provided by the synthesis of d⁶ metal complexes containing the intact molecules P₄ and P₄S₃. The coordinated cage molecules acquire unexpected reactivity and undergo dismutation reactions in mild conditions in the presence of water. The outcomings are obtained either in form of free or coordinated molecules; the former are hypophosphorous and phosphorous acids, the latter comprise, besides phosphine, PH₃, such species as thiophosphinous acid, PH₂SH, diphosphane, P₂H₄, 1-hydroxytriphosphane, PH(OH)PHPH₂ and 1,1,4-tris-hydroxytetraphosphane, P(OH)₂PHPHPH(OH), which are either unknown or extremely reactive as free molecules. The formation of the above molecules provides a clue to the hydrolytic activation of the P₄ and P₄S₃ cage molecules.     

Three‐dimensional imaging of chemical phase transformations at the nanoscale with full‐field transmission X‐ray microscopy

The ability to probe morphology and phase distribution in complex systems at multiple length scales unravels the interplay of nano‐ and micrometer‐scale factors at the origin of macroscopic behavior. While different electron‐ and X‐ray‐based imaging techniques can be combined with spectroscopy at high resolutions, owing to experimental time limitations the resulting fields of view are too small to be representative of a composite sample. Here a new X‐ray imaging set‐up is proposed, combining full‐field transmission X‐ray microscopy (TXM) with X‐ray absorption near‐edge structure (XANES) spectroscopy to follow two‐dimensional and three‐dimensional morphological and chemical changes in large volumes at high resolution (tens of nanometers). TXM XANES imaging offers chemical speciation at the nanoscale in thick samples (>20 µm) with minimal preparation requirements. Further, its high throughput allows the analysis of large areas (up to millimeters) in minutes to a few hours. Proof of concept is provided using battery electrodes, although its versatility will lead to impact in a number of diverse research fields.     

A unified model for adhesive interfaces with damage,viscosity, and friction

A general framework for models describing adhesive contact between rigid bodies is proposed. The intensity of adhesion is supposed to decrease under the action of prescribed tangential and normal relative displacements. The reduction is attributed to progressive damage, and comes with energy dissipation. Additional dissipation due to viscosity and friction is also taken into account. The response of the interface is described by a single state variable. It is determined by general laws expressing a mechanical version of the first two laws of thermodynamics, combined with a set of phenomenological assumptions.     

Wake flow past a plate with spoiler II: Gravity effects

Summary The effects of transverse gravity on steady flow past a split plate are investigated, by adopting the wake model proposed in the preceding paper (I). The existence and uniqueness of the solution as well as the convergence of an iteration process involving the free streamlines are proved for large Froude numbers by means of the Banach contraction mapping principle using Lipschitz norms.

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Sunto Si studiano gli effetti dovuti ad un campo di gravità uniforme trasversale sul flusso con scia attorno ad un profilo sottile con spoiler usando un modello proposto nel precedente lavoro (I). Si dimostra l'esistenza, unicità, e la convergenza di un procedimento iterativo sulle linee di corrente libere, per grandi numeri di Froude, mediante il principio di contrazione in spazi di Banach.