Ab initio and DFT studies on hydrolyses of phosphorus halides

Hydrolyses of phosphorus halides, (RO)(2)POX where R = H or Me and X = F or Cl, in the gas phase and in the reaction field have been investigated theoretically with ab initio and the density functional theory (DFT). The free energy of activation in the reaction field was also estimated using the Onsager method with a correction of entropy change and basis set superposition error (BSSE). The reaction of (MeO)(2)POF proceeds through a path with bifunctional catalysis regardless of the medium, but the reaction of (MeO)(2)POCl proceeds through bifunctional and general base catalysis in the gas phase and in water, respectively. The estimated free energy barrier of 23 kcal/mol for the hydrolysis of (MeO)(2)POF is in good agreement with the experimental values of 24 kcal/mol, and relative barrier of 3 kcal/mol to the (MeO)(2)POCl is also in good agreement with the experimental values of 5 kcal/mol of diisopropyl phosphorus halides ((Pr(i)O)(2)POX, X = F and Cl).     

Synthesis and characterization of a magnetic semiconductor Na(2)RuO(4) containing one-dimensional chains of Ru(6+)

A new ternary ruthenium oxide Na(2)RuO(4) was prepared and shown to crystallize with a new structure type. Single crystal X-ray diffraction measurements reveal that Na(2)RuO(4) consists of RuO(4) chains made up of RuO(5) trigonal bipyramids by sharing axial corners. Na(2)RuO(4) is a magnetic semiconductor with a variable range hopping behavior, and its molar magnetic susceptibility chi(mol) has a broad maximum at approximately 74 K. The derivative d(chi(mol).T)/dT exhibits a peak at 37.7 K which has been confirmed by heat capacity measurement to be due to long-range antiferromagnetic ordering.     

A Sensitive and Selective LC-MS Method for the Determination of Lurasidone in Rat Plasma,Bile, and Urine

A liquid chromatography-mass spectrometry (LC-MS) assay was developed and validated for the quantification of lurasidone, an atypical antipsychotic drug, in rat plasma, bile, and urine. Rat plasma, bile, or urine samples were processed by liquid–liquid extraction and injected onto an LC-MS system for the quantification of lurasidone and ziprasidone (an internal standard). Lurasidone and ziprasidone were separated from endogenous substances using a Gemini C6-Phenyl column with mixture of acetonitrile and 0.1 % formic acid (80:20, v/v) as the mobile phase. Quantification was performed using the selected ion monitoring mode at m/z 493 for lurasidone and m/z 413 for the IS. The detector response was specific and linear for lurasidone in the concentration range 5–5,000 ng mL⁻¹ The intra- and inter-day accuracy and precision of the method were determined to be within the acceptable criteria for assay validation guidelines. In addition, lurasidone was stable under a variety of processing and handling conditions. Lurasidone concentrations could be readily measured in rat plasma, bile, and urine samples up to 24 h after an intravenous or oral administration, suggesting that the assay can be used in pharmacokinetic studies of lurasidone in rats.

     

Preparation of Silver Nanoparticles through Alcohol Reduction with Organoalkoxysilanes

Silver nanoparticles of narrow size distribution were prepared through the chemical reduction in an alcohol solution with several organoalkoxysilanes. In this system, organoalkoxysilanes served as a stabilizer, protecting silver nanoparticles from aggregation. The changes in size and morphology of colloidal silver nanoparticles were investigated with the addition of organoalkoxysilanes such as 3-aminopropyltriethoxysilane (APS), methyltriethoxysilane (MTS), phenyltrimethoxysilane (PTS), vinyltriethoxysilane (VTS), and 3-glycidoxypropyltrimethoxysilane (GPS) as stabilizers. The organic functional groups of organoalkoxysilanes interact with silver ions and clusters, which stabilize silver nanoparticles in the system. The silver nanoparticles obtained were characterized with transmission electron microscopy (TEM), UV-vis spectroscopy, etc.     

Di­cyano{[(1S)‐(1‐phenyl­ethyl)­aziridin‐2‐yl]­methano­lato‐κ2N,O}boron

In the title compound, C₁₃H₁₄BN₃O, the aziridine ring is an almost equilateral triangle, the C—C distance being slightly shorter than the C—N distances, probably because of the dative B—N bond. The five‐membered ring, composed of two C atoms and N, B and O atoms, is fused with the aziridine ring to form a six‐membered ring with a chair conformation.     

Conformational dependence of the intrinsic acidity of the aspartic acid residue sidechain in N-acetyl- -aspartic acid-N′-methylamide

The sidechain conformational potential energy hypersurfaces (PEHS) for the γ_L, β_L, α_L, and α_D backbone conformations of N-acetyl- -aspartate-N′-methylamide were generated. Of the 81 possible conformers initially expected for the aspartate residue, only seven were found after geometric optimizations at the B3LYP/6-31G(d) level of theory. No stable conformers could be located in the δ_L, _L, γ_D, δ_D, and _D backbone conformations. The ‘adiabatic’ deprotonation energies for the endo and exo forms of N-acetyl- -aspartic acid-N′-methylamide were calculated by comparing their optimized relative energies against those found for the seven stable conformers of N-acetyl- -aspartate-N′-methylamide. Sidechain conformational PEHSs were also generated for the estimation of ‘vertical’ deprotonation energies for both endo and exo forms of N-acetyl- -aspartic acid-N′-methylamide. All backbone–sidechain (N–H⁻O–C) and backbone–backbone (N–HO=C) hydrogen bond interactions were analyzed. A total of two backbone–backbone and four backbone–sidechain interactions were found for N-acetyl- -aspartate-N′-methylamide. The deprotonated sidechain of N-acetyl- -aspartate-N′-methylamide may allow the aspartyl residue to form strong hydrogen bond interactions (since it is negatively charged) which may be significant in such processes as protein–ligand recognition and ligand binding. As a primary example, the molecular geometry of the aspartyl residue may be important in peptide folding, such as that in the RGD tripeptide.     

Quantitative determination of enzalutamide,an anti‐prostate cancer drug,in rat plasma using liquid chromatography–tandem mass spectrometry,and its application to a pharmacokinetic study

This report details a method using liquid chromatography–tandem mass spectrometry (LC‐MS/MS) that allows one to determine the concentration of an atypical anticancer drug, enzalutamide, in rat plasma. Specifically, this method involves the addition of an acetonitrile and bicalutamide (internal standard) solution to plasma samples. Following centrifugation of this mixture, an aliquot of the supernatant was directly injected into the LC‐MS/MS system. Separation was achieved using a column packed with octadecylsilica (5 µm, 2.1 × 50 mm) with 10 mM ammonium acetate in acetonitrile as the mobile phase; detection was accomplished using MS/MS by multiple‐reaction monitoring via an electrospray ionization source. This method demonstrated a linear standard curve (r = 0.997) over a concentration range of 0.001–1 µg/mL, as well as an intra‐ and inter‐assay precision of 2.7 and 5.1%, respectively, and an accuracy range from 100.8 to 105.6%. The lower limit of quantification was 1.0 ng/mL in 50 μL of rat plasma sample. We also demonstrated that this analytical method could be successfully applied to the pharmacokinetic study of enzalutamide in rats. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of a Zn-salen resorcinarene-based cavitand and its fluorescence response to nitro compounds

The synthesis, spectroscopic characterisation, conformational switching and fluorescence quenching efficiency of a resorcinarene-based cavitand containing Zn-salen (Zn-Cav) are reported. Synthesis of Zn-Cav was accomplished by the condensation of a quinoxaline derivatised with Zn-salen and a resorcinarene-based cavitand containing three quinoxalines. ¹H NMR spectroscopy confirmed that in DMSO, chloroform and acetone Zn-Cav resides in the vase conformation. The molecular geometry of Zn-Cav selectively changes from vase to kite under acidic conditions. Detection by fluorescence quenching of nitro-containing molecules, such as 4-nitrotoluene, 2,4-dinitrotoluene and 2,3-dimethyl-2,3-dinitrobutane was explored by spectrofluorimetry. It was found that the fluorescence of Zn-Cav is efficiently quenched by nitroaromatic compounds.     

Topography and field effects in the inner side of microvia hole using ToF‐SIMS

We have developed a simple and powerful method, which is called ‘angled sample holder method’, to characterize a topographic structured sample such as microsized via hole of ball grid array using time‐of‐flight SIMS. The diameter of via holes was 100 µm and the depth was 70 µm. To remove the shaded area by incidence primary ion beam and to extract secondary ions from the bottom of a via hole, several types of angled sample holders with compensation steering plate were applied on the basis of simulation results using SIMION code. And the analyses using angled sample holder method enabled us to characterize the bottom and side wall of a via hole in clear. Copyright © 2014 John Wiley & Sons, Ltd.     

Hydrolytic Transformation of Microporous Metal–Organic Frameworks to Hierarchical Micro‐ and Mesoporous MOFs

A new approach to the synthesis of hierarchical micro‐ and mesoporous MOFs from microporous MOFs involves a simple hydrolytic post‐synthetic procedure. As a proof of concept, a new microporous MOF, POST‐66(Y), was synthesized and its transformation into a hierarchical micro‐ and mesoporous MOF by water treatment was studied. This method produced mesopores in the range of 3 to 20 nm in the MOF while maintaining the original microporous structure, at least in part. The degree of micro‐ and mesoporosity can be controlled by adjusting the time and temperature of hydrolysis. The resulting hierarchical porous MOF, POST‐66(Y)‐wt, can be utilized to encapsulate nanometer‐sized guests such as proteins, and the enhanced stability and recyclability of an encapsulated enzyme is demonstrated.