A Fluorescent Ditopic Rotaxane Ion‐Pair Host

We report a rotaxane based on a simple urea motif that binds Cl^? selectively as a separated ion pair with H⁺ and reports the anion binding event through a fluorescence switch‐on response. The host selectively binds Cl^? over more basic anions, which deprotonate the framework, and less basic anions, which bind more weakly. The mechanical bond also imparts size selectivity to the ditopic host.     

Electrochemical approaches for the fabrication and/or characterization of pure and hybrid templated mesoporous oxide thin films: a review

Electrochemistry can be used for fabrication and characterization of mesoporous oxide films. First, this review provides insight into the methods used to prepare templated mesoporous thin films on an electrode surface, i.e., evaporation-induced self-assembly (EISA) and electrochemically assisted self-assembly (EASA). Electrochemical characterization of mass transport processes in pure and organically functionalized mesoporous oxide films is then discussed. The electrochemical response can be basically restricted by the electron/mass transfer reaction at the electrode–film interface and diffusion through mesopore channels. The contributions of cyclic voltammetry, hydrodynamic voltammetry, electrochemical impedance spectroscopy, and scanning electrochemical microscopy to the characterization of films with distinct mesostructures are finally described, with special emphasis on identification of conditions that can affect the electrochemical response recorded with such modified electrodes.

Structure determination of a new cocrystal of carbamazepine and dl‐tartaric acid by synchrotron powder X‐ray diffraction

The crystal structure of a new cocrystal of carbamazepine (systematic name: 5H‐dibenzo[b,f]azepine‐5‐carboxamide, C₁₅H₁₂N₂O) and dl ‐tartaric acid (C₄H₆O₆), obtained by liquid‐assisted grinding, was solved by powder X‐ray diffraction (PXRD). The high‐resolution PXRD pattern of this new phase was recorded at room temperature thanks to synchrotron experiments at the European Synchrotron Radiation Facility (Grenoble, France). The starting structural model was generated by a Monte‐Carlo simulated annealing method. The final structure was obtained through Rietveld refinement and an energy minimization simulation was used to estimate the H‐atom positions. The stability of the proposed structure as a function of temperature was also assessed from molecular dynamics simulations. The symmetry is monoclinic (space group P2₁/c) and contains eight molecules per unit cell, namely, four dl ‐tartaric acid and four carbamazepine molecules.     

Calorimetric investigation of the structural relaxation and crystallization of amorphous Ge16Te84 alloys

Differential scanning calorimetric measurements have been performed on amorphous Ge₁₆Te₈₄ alloys; the study of the dependence of the cooling rate on the reciprocal fictive temperature yields the activation energy of the relaxation process; this value fits well that deduced from shear viscosity measurements. The enthalpy difference between the supercooled liquid and the crystal has been investigated by drop calorimetry on samples annealed at different temperatures below T_g, during different times. These results, combined with the former obtained by DSC lead to the enthalpy values of the metastable liquid system from 390 to 510 K.     

Photon energy dependence of fragmentation of small argon clusters

Photofragmentation of small argon clusters with size below ten atoms is reported. In this size range significant modifications from the electronic properties and geometry take place. When tuning the photon energy through the argon 2p edge, the fragmentation pattern is changed. Specifically, cation dimer production is enhanced at the 2p(32)-->4s resonance, while above the 2p edge almost complete atomization is observed. In both cases, the widths of the peaks in the mass spectra indicate that a large amount of kinetic energy is imparted to the fragment due to the formation of multiply charged clusters. A model based on "Coulomb explosion"-charge separation, simply resulting in a complete atomization of the cluster with no dependence on the photon energy-is insufficient to explain the observed photofragmentation of small clusters.     

Composition dependence of fundamental edge in Ga1−xAlxSb alloys

The fundamental edge of Ga_1-xAl_xSb alloys has been measured at room temperature. Piezomodulated reflection and transmission measurements permited to obtain the variation with composition of the Γ_15v ? Γ_1c and Γ_15v ? X_1c gaps and to deduce for the direct indirect crossover composition a value of x_c = 0.4 ± 0.02.     

Preparation of chiral ruthenium(IV) complexes and applications in regio- and enantioselective allylation of phenols

Facile preparations of chiral [Ru(Cp*)]- and [Ru(Cp')]-based allyl complexes featuring N,O chelate derived from (+)-nopinone are described. Single crystal X-ray structural analysis of one complex revealed the preferential configuration of the ruthenium centre and the orientation of the unsymmetrical allylic substituent. Applications of these complexes in catalysis for nucleophilic allylic substitution allowed regio- and enantioselective formation of branched allyl ethers from phenols.     

Borylation of Unactivated Aryl Chlorides under Mild Conditions by Using Diisopropylaminoborane as a Borylating Reagent

The synthesis of arylboronic ester derivatives from aryl chlorides by using aryl(amino)boranes is described. Palladium‐catalyzed coupling between aryl chlorides and diisopropylaminoborane leads to the formation of a C?B bond under mild conditions. A wide range of functional groups are tolerated, making this method particularly useful for the borylation of functionalized aromatics.