Nanocrystalline Li<Subscript>2</Subscript>TiO<Subscript>3</Subscript> electrodes for supercapattery application

Nanocrystalline Li₂TiO₃ was successfully synthesized using solid-state reaction method. The microstructural and electrochemical properties of the prepared material are systematically characterized. The X-ray diffraction pattern of the prepared material exhibits predominant (002) orientation related to the monoclinic structure with C2/c space group. HRTEM images and SAED analysis reveal the well-developed nanostructured particles with average size of ～40 nm. The electrochemical properties of the prepared sample are carried out using cyclic voltammetry (CV) and chronopotentiometry (CP) using Pt//Li₂TiO₃ cell in 1 mol L^?1 Li₂SO₄ aqueous electrolyte. The Li₂TiO₃ electrode exhibits a specific discharge capacity of 122 mAh g^?1; it can be used as anode in Li battery within the potential window 0.0–1.0 V, while investigated as a supercapacitor electrode, it delivers a specific capacitance of 317 F g^?1 at a current density of 1 mA g^?1 within the potential range ?0.4 to +0.4 V. The demonstration of both anodic and supercapacitor behavior concludes that the nanocrystalline Li₂TiO₃ is a suitable electrode material for supercapattery application.     

Crystal Structure of a Second Polymorph of Gabapentin Hydrochloride Hemihydrate with a Three-Center Bifurcated Hydrogen Bond

Abstract  

Gabapentin hydrochloride hemihydrate, a derivative of Gabapentin [or 1-(aminomethyl) cyclohexaneacetic acid; Gpn, C₆H₁₇NO₂], is a salt of C₉H₁₈NO₂ ⁺ Cl⁻ 0.5 H₂O, which crystallizes in the monoclinic space group I 2/a with unit cell parameters a = 13.2467(3), b = 6.5552(2), c = 26.0094(8) ?, β = 96.561(3)°, Z = 8. The crystal structure and bonding network is compared to its isostructural and previously reported polymorphic derivative, Gpn hydrochloride hemihydrate [C₉H₁₇NO₂ HCl ? H₂O]. Both of these derivatives exhibit extensive inter and intra molecular hydrogen bonding networks between the NH₃ ⁺ group and neighboring Cl⁻, water and carboxyl oxygen atoms as well as similar interactions between the chloride anion and nearby water and carboxyl oxygen atoms. A unique and relatively rare three-center hydrogen bond configuration (with a bifurcated chlorine Cl⁻···H–(N,O) and Cl⁻···H–O acceptor hydrogen bonds) as well as N–H···O donor hydrogen bonds can be seen linking the molecules into chains along the [1 0 1] plane of the unit cell.     

An Efficient Stereoselective Synthesis of Key Fragments of Elaiophylin

The stereoselective synthesis of key fragments 3 and 7 of elaiophylin has been accomplished from readily available epichlorohydrin as the starting material. The key reactions involved are Jacobsen's kinetic resolution, Prins cyclization, pyridinium chlorochromate‐mediated oxidative cleavage, Grignard reaction, and cross‐metathesis reaction.     

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     

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.