Linear chain aluminium(III) carboxymethylphosphonate with encapsulated ammonium ions

An aluminium carboxymethylphosphonate of composition (NH(4))(2)Al(H(1/2)O(3)PCH(2)CO(2))(2) has been prepared hydrothermally. The aluminium cation is chelated by six membered rings formed from bonding by both the carboxylate and phosphonate oxygens. These chelate rings in turn form larger eight membered rings by connecting to similar chelate groups to form chains running along the a-axis.     

Carbene-stabilized diphosphorus: bidentate complexation of BH2(+)

Reaction of carbene-stabilized diphosphorus, L:P-P:L (L: = :C{N(2,6-Pr(i)(2)C(6)H(3))CH}(2), 1), with excess BH(3)·THF affords the boronium salt [L:P(μ-BH(2))P:L](+)[B(2)H(7)](-), 2, which contains a three-membered P(2)B ring. When 2 is dissolved in THF, compounds 1 and 2 exist in a dynamic solution equilibrium.     

Seebeck coefficients in ionic liquids--prospects for thermo-electrochemical cells

Measurement of Seebeck coefficients in a range of ionic liquids (ILs) suggests that these electrolytes could enable the development of thermoelectric devices to generate electrical energy from low-grade heat in the 100-150 °C range.     

NMR chromatography using microemulsion systems

NMR spectroscopy is an excellent tool for structural analysis of pure compounds. However, for mixtures, it performs poorly because of overlapping signals. Diffusion ordered NMR spectroscopy (DOSY) can be used to separate the spectra of compounds with widely differing molecular weights, but the separation is usually insufficient. NMR "chromatographic" methods have been developed to increase the diffusion separation but these usually introduced solids into the NMR sample that reduce resolution. Using nanostructured dispersed media, such as microemulsions, eliminates the need for suspensions of solids and brings NMR chromatography into the mainstream of NMR analytical techniques. DOSY was used in this study to resolve spectra of mixtures with no increase in line-width as compared to regular solutions. Components of a mixture are differentially dissolved into the separate phases of the microemulsions. Several examples of previously reported microemulsions and those specifically developed for this purpose were used here. These include a fully dilutable microemulsion, a fluorinated microemulsion, and a fully deuterated microemulsion. Log(diffusion) difference enhancements of up to 1.7 orders of magnitude were observed for compounds that have similar diffusion rates in conventional solvents. Examples of commercial pharmaceutical drugs were also analyzed via this new technique, and the spectra of up to six components were resolved from one sample.     

Dielectric confinement on exciton binding energy and nonlinear optical properties in a strained Zn1-xinMgx（in）Se/Zn1-x（out）Mgx（out）Se quantum well

正The band offsets for a Zn_(1-Xin)Mg_(Xin)Se/Zn_(1-Xout)Mg_(1-Xout)Se quantum well heterostructure are determined using the model solid theory.The heavy hole exciton binding energies are investigated with various Mg alloy contents.The effect of mismatch between the dielectric constants between the well and the barrier is taken into account.The dependence of the excitonic transition energies on the geometrical confinement and the Mg alloy is discussed.Non-linear optical properties are determined using the compact density matrix approach.The linear,third order non-linear optical absorption coefficient values and the refractive index changes of the exciton are calculated for different concentrations of magnesium.The results show that the occurred blue shifts of the resonant peak due to the Mg incorporation give the information about the variation of two energy levels in the quantum well width.     

Electroanalytical studies of the corrosion-protection properties of 4-amino-4H-1,2,4-triazole-3,5-dimethanol (ATD) on mild steel in 0.5?N sulfuric acid

Inhibition of the corrosion of mild steel in aerated 0.5?N H₂SO₄ solution by 4-amino-4H-1,2,4-triazole-3,5-dimethanol (ATD) was investigated by use of potentiodynamic polarization (Tafel), electrochemical impedance spectroscopy, adsorption, and surface morphological studies. The effects on the rate of corrosion of inhibitor concentration, temperature, extent of surface coverage, adsorption kinetics, and surface morphology were investigated. Inhibition efficiency increased markedly with increasing ATD concentration and decreased slightly with increasing temperature. The presence of ATD reduced the capacitance of the double layer and increased the charge-transfer resistance. Values of the activation energy (E _a) and of the thermodynamic data adsorption equilibrium constant (K _ads) and free energy of adsorption (??G _ads) were computed from the temperature dependence of the corrosion current. The inhibitor molecule first became adsorbed on the mild steel surface, obeying the Langmuir adsorption isotherm, and substantially reduced the rate of corrosion. Results of electroanalytical studies revealed that ATD acts as a mixed-type inhibitor.     

Surface crystallization of rapamycin on stents using a temperature induced process

Metallic drug eluting stents (DES) are usually prepared by coating with a drug-polymer matrix as a rate controlling diffusion barrier. However, coating materials may display numerous problems, thus carrier-free DES are desired, yet releasing drug over long period of time. For this, we are reporting a novel temperature induced (TI) crystallization process for coating rapamycin on stents. Rapamycin crystals with a defined morphology and target drug load were applied from supersaturated solution. This method enables fabrication of controllable and homogeneous crystalline coatings on stent scaffolds and allowing the drug to release for several weeks.     

Reactions of Microsolvated Organic Compounds at Ambient Surfaces: Droplet Velocity,Charge State,and Solvent Effects

The exposure of charged microdroplets containing organic ions to solid-phase reagents at ambient surfaces results in heterogeneous ion/surface reactions. The electrosprayed droplets were driven pneumatically in ambient air and then electrically directed onto a surface coated with reagent. Using this reactive soft landing approach, acid-catalyzed Girard condensation was achieved at an ambient surface by directing droplets containing Girard T ions onto a dry keto-steroid. The charged droplet/surface reaction was much more efficient than the corresponding bulk solution-phase reaction performed on the same scale. The increase in product yield is ascribed to solvent evaporation, which causes moderate pH values in the starting droplet to reach extreme values and increases reagent concentrations. Comparisons are made with an experiment in which the droplets were pneumatically accelerated onto the ambient surface (reactive desorption electrospray ionization, DESI). The same reaction products were observed but differences in spatial distribution were seen associated with the “splash” of the high velocity DESI droplets. In a third type of experiment, the reactions of charged droplets with vapor phase reagents were examined by allowing electrosprayed droplets containing a reagent to intercept the headspace vapor of an analyte. Deposition onto a collector surface and mass analysis showed that samples in the vapor phase were captured by the electrospray droplets, and that instantaneous derivatization of the captured sample is possible in the open air. The systems examined under this condition included the derivatization of cortisone vapor with Girard T and that of 4-phenylpyridine N-oxide and 2-phenylacetophenone vapors with ethanolamine.     

A Designed Inhibitor of a CLC Antiporter Blocks Function through a Unique Binding Mode

1. Download : Download high-res image (148KB)
2. Download : Download full-size image

Highlights? OADS is a known small-molecule inhibitor of a CLC antiporter ? OADS specifically inhibits the ClC-ec1 antiporter but not the ClC-1 channel ? Photoaffinity labeling and mass spectrometry have localized OADS binding to two discrete sites ? The unique binding mode and lipid dependence of OADS suggest potential mechanisms of action     

Equations for the Partition of Neutral Molecules, Ions and Ionic Species from Water to Water–Ethanol Mixtures

Equations set up for the transfer of neutral solutes from water to water?Cethanol mixtures can also be used to correlate the transfer of ions and ionic species, as log₁₀ P, where P is the partition coefficient. Only two additional terms are required in the equations, one for anions and one for cations. The extended equations can fit log₁₀ P values for anions and cations with a standard deviation of about 0.2 to 0.3 log units for transfer of 41 anions and cations from water to various water?Cethanol mixtures from 10?% ethanol to 100?% ethanol by volume. The log₁₀ P values for carboxylate anions and protonated amine cations as obtained from the variation of pK _a with solvent are quite compatible with log₁₀ P values for simple anions and cations.