The effect of oxygen partial pressure on physical properties of nano‐crystalline silver oxide thin films deposited by RF magnetron sputtering

Nano‐crystalline silver oxide films were deposited on glass and silicon substrates held at room temperature by RF magnetron sputtering of silver target under different oxygen partial pressures. The influence of oxygen partial pressure on the structural, morphological, electrical and optical properties of deposited films was investigated. Varying oxygen partial pressure during the sputter deposition leads to changes of mixed phase of Ag₂O and Ag to a single phase of Ag₂O and to AgO. The X‐ray diffraction and X‐ray photoelectron spectroscopy results showed the formation of single phase Ag₂O with cubic structure at oxygen partial pressures of 2x10^‐2 Pa while the films deposited at higher oxygen partial pressure of 9x10^‐2 Pa showed the formation of single phase of AgO with monoclinic structure. Raman spectroscopic studies on the single phase Ag₂O showed the stretching vibration of Ag‐O bonds. Single‐phase Ag₂O films obtained at oxygen partial pressure of 2x10^‐2 Pa were nano‐crystalline with crystallite size of 20 nm and possessed an electrical resistivity of 5.2x10^‐3 Ωcm and optical band gap of 2.05 eV. The films deposited at higher oxygen partial pressure of 9x10^‐2 Pa were of AgO with electrical resistivity of 1.8x10^‐2 Ωcm and optical band gap of 2.13 eV. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis and Crystal Structures of Two New Schiff Base Hydrazones Derived from Biphenyl-4-Carbohydrazide

Abstract  

The crystal structures of two novel Schiff base hydrazones have been determined by means of the X-ray diffraction. These compounds: N′-[(E)-(2,5-dimethoxyphenyl)methylidene]biphenyl-4-carbohydrazide, C₂₂H₂₀N₂O₃ (1) and N′-[(E)-(4-fluorophenyl)methylidene]biphenyl-4-carbohydrazide, C₂₀H₁₅FN₂O (2), are the first structurally characterized biphenyl derivatives of phenylmethylidene-carbohydrazide. Both compounds crystallize in the monoclinic space groups, 1 in P2₁/c space group with a = 13.987(2) ?, b = 16.426(3) ?, c = 8.214(2) ?, β = 98.12(2)°, and 2 in C2/c with a = 37.163(5) ?, b = 10.696(2) ?, c = 8.098(2) ?, β = 101.18(2)°. Both molecules have very similar bond lengths and angles pattern, even in the differently substituted phenyl ring. However, the conformations of the molecules differ significantly, the more crowded molecule 1 is much more folded than 2. The dihedral angle between the terminal ring planes is 56.17(6)° in 1 while in 2 it is as small as 2.83(14)°. In both structures relatively short and linear N–H···O hydrogen bonds (created by the best available hydrogen bond donor and acceptor) connect molecules into the chains along the unit cell parameter of ca. 8 ? in length. The next stage of the crystal architecture determination, the secondary interactions, are however quite different: in 1 there are almost solely dispersion van der Waals interactions while in 2 some more specific C–H···F and C–H···π interactions are also involved in the crystal packing.     

Using surface‐enhanced Raman scattering (SERS) and fluorescence spectroscopy for screening yeast extracts,a complex component of cell culture media

Yeastolate or yeast extract, which are hydrolysates produced by autolysis of yeast, are often employed as a raw material in the media used for industrial mammalian cell culture. The source and quality of yeastolate can significantly affect cell growth and production; however, analysis of these complex biologically derived materials is not straightforward. The best current method, liquid chromatography–mass spectrometry (LC‐MS), is time‐consuming and requires extensive expertise. This study describes the use of surface‐enhanced Raman scattering (SERS) and fluorescence excitation–emission matrix (EEM) spectroscopy coupled with robust principal component analysis (ROBPCA) for the rapid and facile characterization and discrimination of yeast extracts in aqueous solution. SERS using silver colloids generates time‐dependent signals, where adenine is the strongest contributor, and the spectra are stable and reproducible (< ~3%) at 180 min after mixing. Combining this spectral behavior with chemometric methods enables SERS to be used in discriminating between different yeastolate sources, for assessing lot‐to‐lot variability, and, potentially, to monitor storage‐induced compositional changes. Fluorescence EEM combined with multiway ROBPCA also provides a rapid and inexpensive method for the discrimination of yeastolate, yielding results in terms of sample discrimination very similar to that obtained with SERS. However, the EEM data does not provide the same level of chemical information that is provided by the SERS. Thus, the combination of these two methodologies has the potential to be extremely useful in biopharmaceutical manufacturing, as well as for the rapid characterization and screening of biogenic hydrolysates from animal or plant sources. Copyright © 2011 John Wiley & Sons, Ltd.     

Unusual room temperature CO(2) uptake in a fluoro-functionalized MOF: insight from Raman spectroscopy and theoretical studies

We herein report an unusual CO(2) adsorption behavior in a fluoro-functionalized MOF {[Zn(SiF(6))(pyz)(2)]·2MeOH}(n) (1) with a 1D channel system, which is made up of pyrazine and SiF(6)(2-) moieties. Surprisingly, desolvated 1 (1') adsorbs higher amounts of CO(2) at 298 K than at 195 K, which is in contrast to the usual trend. Combined Raman spectroscopic and theoretical studies reveal that slanted pyrazine rings in 1' with an angle of 17.2° with respect to the (200) Zn(ii)-Si plane at low temperature block the channel windows and thus reduce the uptake amount.     

The first stereoselective total synthesis of the Z-isomer of cytospolide E

A convergent and highly stereoselective total synthesis of the Z-isomer of cytospolide E has been achieved via Evan’s aldol reaction, Sharpless kinetic resolution and RCM cyclisation.     

Synthesis and antiosteoclast activity of Di(1‐oxo/thioxoperhydro‐1λ5‐[1,3,2] diazaphospholo [1,5‐a]pyridine‐1‐yl) (4‐substituted phenyl) boronates

A new family of di(1‐oxo/thioxoper‐hydro‐1λ⁵‐[1,3,2]diazaphospholo[1,5‐a]pyridine‐1‐yl)(4‐substituted phenyl) boronates ( 4a – j ) has been synthesized in a two‐step process. A reaction of (±)‐piperidin‐2‐yl‐methanamine ( 1 ) phosphoryl/phosphorothioyl chloride in the presence of triethylamine in dry tetrahydrofuran formed the intermediate monochloride ( 2 ), which on condensation with p‐substituted phenylboronic acids ( 3a – j ) afforded the titled compounds ( 4a – j ). They were characterized by elemental, IR, ¹H, ¹³C, ³¹P NMR, and mass spectral analyses. All these compounds showed moderate to high antiosteoclast and osteoblast activity. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:247–253, 2012; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.21010     

Solution growth of new ferroelectric glycine phosphite unidirectional single crystals at room temperature

Glycine phosphite [NH₃CH₂COOH₃PO₃], abbreviated as GPI is the second hydrogen bonded ferroelectric crystal combination of phosphorous acid and amino acid following βnine phosphite crystals abbreviated as BPI. Sankaranarayanan and Ramasamy‐Technique was adopted to prepare the ferroelectric glycine phosphite unidirectional single crystal. The growth orientation was imposed by the pre‐grown 〈010〉 seed. As water was the solvent, transparent, colourless crystal with cylindrical shaped ingot of sized 20mm‐diameter was grown. Powder X‐ray diffraction, HRXRD, FTIR, dielectric and mechanical studies were carried out. The results are discussed in detail. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structures of substituted imidazolidine derivatives

The crystal structures of isoxazole, 3-[[dihydro-2-[(Z)-2-oxohyrazono]-1H-imidazol-1-(3H)-yl]methyl-5-phenyl-,N-oxide] (C₁₃H₁₃N₅O₃) (I), isoxazole,3-[[dihydro-2-[(Z)-2-oxohyrazono]-1H-imidazol-1-(3H)-yl]-methyl-5-(4-methylphenyl)-,N-oxide] (C₁₄H₁₅N₅O₃) (II) and isoxazole, 3-[[dihydro-2-[(Z)-2-oxohyrazono]-1H-imidazol-1-(3H)-yl]-methyl-5-(2-methoxyphenyl)-,N-oxide] (C₁₄H₁₅N₅O₄) (III) have been determined by X-ray diffraction studies. The compound I, crystallized in triclinic space group with unit cell dimensions a = 7.2405(7) ?, b = 7.9936(8) ?, c = 11.6573(11) ?, α = 97.801(2)°, β = 90.884(2)°, γ = 96.250(2)° and Z = 2. Compound II crystallized in orthorhombic space group Pna2₁ with unit cell dimensions a = 10.1778(10) ?, b = 28.228(3) ?, c = 5.1206(5) ?, and Z = 4. Compound III crystallized in monoclinic space group P2₁/n with unit cell dimensions a = 7.8439(9) ?, b = 7.8544(9) ?, c = 23.534(3) ?, β = 99.464(2)° and Z = 4. For all three compounds, the five-membered imidazolidine ring adopts an envelope conformation. The crystal structures are stabilized by both the intramolecular N–H···O and intermolecular N–H···N hydrogen bonding.