Extreme‐ultraviolet compact spectrometer for the characterization of the harmonics content in the free‐electron‐laser radiation at FLASH

The design and the commissioning results of a portable and compact spectrometer for the high harmonics content characterization of the extreme‐ultraviolet radiation of FLASH (free‐electron laser in DESY, Hamburg, Germany) are presented. The instrument is a grazing‐incidence flat‐field spectrometer equipped with two variable‐line‐spaced gratings; it covers the 2–40 nm wavelength region with a spectral resolution in the 0.1–0.2% range. Both spectral and intensity fluctuations of the fundamental emission and the harmonics are monitored.     

Hydrodynamic simulation of a n + − n − n + silicon nanowire

Non-equilibrium electron transport in silicon nanowires has been tackled with a hydrodynamic model. This model has been formulated by taking the moments of the multisubband Boltzmann equation, coupled to the Schrödinger–Poisson system. Closure relations are obtained by means of the maximum entropy principle (MEP) of extended thermodynamics, including scattering of electrons with acoustic and nonpolar optical phonons. Simulation results for a quantum n ⁺ ? n ? n ⁺ silicon diode are shown.     

A chromium-free synthesis of enantiopure 5-oxoborneol

Enantiopure (−)-5-oxoborneol was obtained in 35% overall yield in two steps, starting from readily available (−)-bornyl acetate and using oxone® as a safe and inexpensive oxidant. The reported procedure avoids the use of large excess of noxious chromium(VI), which was required by the so far reported syntheses.     

Structure elucidation of the dye Acid Red 131: complete 1H, 13C and 15N NMR data assignment

The chemistry of dyes and pigments is relevant to the textile industry, because of the importance to establish the best conditions for the finishing process and to understand the interactions among various compounds to yield the correct hue and nuances. For this reason, the molecular structure of a monoazo acid dye, C.I. Acid Red 131, was elucidated and characterized by homo‐ and hetero‐nuclear NMR, MS, IR and UV spectroscopy techniques. Copyright © 2011 John Wiley & Sons, Ltd.     

Silver-Free Au(I) Catalysis Enabled by Bifunctional Urea- and Squaramide-Phosphine Ligands via H-Bonding

A library of gold(I) chloride complexes with phosphine ligands incorporating pendant (thio)urea and squaramide H-bond donors was prepared with the aim of promoting chloride abstraction from Au(I) via H-bonding. In the absence of silver additives, complexes bearing squaramides and trifluoromethylated aromatic ureas displayed good catalytic activity in the cyclization of N-propargyl benzamides, as well as in a 1,6-enyne cycloisomerization, a tandem cyclization-indole addition reaction and the hydrohydrazination of phenylacetylene. Kinetic studies and DFT calculations indicate that the energetic span of the reaction is accounted by both the chloride abstraction step, facilitated by the bidentate H-bond donor via an associative mechanism, and the subsequent cyclization step.