129Xe NMR as a probe of polymer blends

The miscibility of two-component polymer blends has been investigated using xenon-129 (¹²⁹Xe) nuclear magnetic resonance (NMR) to probe the phase morphology. The chemical shift of ¹²⁹Xe dissolved in a given polymer is unique, thus heterogeneous blends with large domain sizes exhibit two ¹²⁹Xe NMR lines. When a single resonance is obtained, the data are consistent with miscibility, yielding an upper bound on the domain size. The temperature dependence of the relative solubilities and chemical shifts of ¹²⁹Xe dissolved in the pure components may allow a determination of the phase morphology in blends exhibiting a single resonance. The method is used to demonstrate that polychloroprene and 25% epoxidized 1,4-polyisoprene form a miscible blend.     

ChemInform Abstract: Characterization of the Oxo-Anions of Bromine BrO- x (x = 1-4) by IR,NMR, and Bromine K-Edge Extended X-Ray Absorption Fine Structure Techniques.

This detailed spectroscopic and structural study of the complete series BrO- x (x = 1-4) for the first time yields a value for the bond length in the hypobromite ion.     

ChemInform Abstract: Multinuclear Magnetic Resonance Studies of the Hydrolysis of Aluminum(III). Part 8. Base Hydrolysis Monitored at Very High Magnetic Field.

Using high-field ¹H and ²⁷Al NMR spectroscopy with increased sensitivity data can be obtained at concentrations as low as 1·10^-3 mol/dm³.     

Bonding analysis for NgAuOH (Ng = Kr,Xe)

Noble‐gas‐noble‐metal hydroxides NgAuOH (Ng = Kr, Xe) are investigated at the MP2 theoretical level. All species are found to be in Cs symmetry with an approximate linear Ng? Au? O moiety. The noble‐gas‐noble‐metal bond lengths are comparable with covalent limits, and the corresponding binding energies have been computed to be 59.6 and 83.4 kJ/mol for KrAuOH and XeAuOH, respectively. Except the charge‐induced dipole contribution to the binding energies, the remainder could be ascribed to the higher‐order charge‐induction energies, dispersion energies, the contributions of multipole moments on AuOH and covalent effects. The title species are sufficiently chemical bound and are expected to be stable species theoretically. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

ChemInform Abstract: Steric Activity of the Central Atom Free Valence Electron Pairs in Free BrF- 6 and IF- 6 Ions.

Raman polarization and ¹⁹F NMR spectra are recorded for MeCN solutions of CsBrF₆ and CsIF₆.     

ChemInform Abstract: C70 Fulleryl Radicals.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

超极化129Xe核磁共振技术及其在多孔催化材料研究中的应用

 激光抽运和自旋交换的超极化 129Xe 核磁共振是近几年发展起来的一种新方法,它比普通 129Xe 核磁共振的检测灵敏度提高约104 ～105倍,是研究材料孔结构和孔内粒子分布的强有力工具. 本文介绍了超极化 129Xe 核磁共振技术并综述了其在多孔催化材料研究中的应用,特别是对催化反应中广泛使用的无机微孔和介孔材料中的应用进行了详细的讨论. 最后展望了此技术的应用前景.     

ChemInform Abstract: Endohedrally Filled [Ni@Sn9]4‐and [Co@Sn9]5‐Clusters in the Neat Solids Na12Ni1‐xSn17 and K13‐xCo1‐xSn17: Crystal Structure and 119Sn Solid‐State NMR Spectroscopy.

The title Zintl phases are prepared by reactions of the corresponding elemental alkali metals with pre‐prepared M‐Sn alloys (M: Ni, Co) at 550—880 °C for 48 h.     

ChemInform Abstract: Electronic Spectra of the Solvated Cations of Chromium(III) and Manganese(II) in Anhydrous Hydrogen Fluoride.

The UV/VIS spectra of Cr(OH₂)₆³⁺ and Mn(OH₂)₆²⁺ in H₂O and of Cr(FH)₆³⁺ and Mn(FH)₆²⁺ in anhydrous HF are recorded.     

ChemInform Abstract: NMR Characterization of the Na3AlP3O9N and Na2Mg2P3O9N Nitridophosphates: Location of the (NaAl)/Mg2 Substitution.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

ChemInform Abstract: 7Li and 29Si Solid State NMR and Chemical Bonding of La2Li2Si3.

The title compound is synthesized from the elements (flowing Ar, Nb ampule, 1000 K, 48 h) and characterized by powder and single crystal XRD, ⁷Li and ²⁹Si MAS NMR spectroscopy, and DFT electronic structure calculations.     

On the porous structure of coals: Evidence for an interconnected but constricted micropore system and implications for coalbed methane recovery

An experimental and theoretical study of adsorption and diffusion of carbon dioxide and methane in coals of widely varying rank was carried out. Low pressures adsorption isotherms of CO₂ were obtained and analyzed using Dubinin's theory of volume filling of micropores. High-pressure adsorption isotherms of CH₄ were obtained and analyzed using tracer pulse chromatography in conjunction with an appropriate adsorption/diffusion model. A preliminary¹²⁹Xe NMR analysis of chemical shifts experienced by xenon atoms in particles of different sizes is also reported.The heretofore undocumented and/or underestimated effects of activated diffusion of CO₂ at 273–298 K complicate the elucidation of the true microporous structure of coals, especially its dependence on coal rank. Activated diffusion of both CO₂ and methane at room temperature does not allow reliable estimates of coalbed gas content to be made. A model of an interconnected network of pores which includes randomly distributed, numerous and ultramicroporous constrictions (at any size scale) is consistent with all these experimental and theoretical findings.Presented in part at the International Conference on Coal Science, Banff, Alberta, Canada. September 1993, and at the 21st Biennial Conference on Carbon, Buffalo, NY, June 1993.     

ChemInform Abstract: Spectroscopic and Structural Studies of Difluorophosphoryl Azide F2P(O)N3, Difluorophosphoryl Isocyanate F2P(O)NCO,and Difluorophosphoric Acid Anhydride,F2(O)POP(O)F2.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

NMR and MRI of blood-dissolved hyperpolarized Xe-129 in different hollow-fiber membranes

Magnetic resonance of hyperpolarized (129)Xe has found a wide field of applications in the analysis of biologically relevant fluids. Recently, it has been shown that the dissolution of hyperpolarized gas into the fluid via hollow-fiber membranes leads to bubble-free (129)Xe augmentation, and thus to an enhanced signal. In addition, hollow-fiber membranes permit a continuous operation mode. Herein, a quantitative magnetic resonance imaging and spectroscopy analysis of a customized hollow-fiber membrane module is presented. Different commercial hollow-fiber membrane types are compared with regard to their (129)Xe dissolution efficiency into porcine blood, its constituents, and other fluids. The presented study gives new insight into the suitability of these hollow-fiber membrane types for hyperpolarized gas dissolution setups.     

ChemInform Abstract: ESR Investigation of the HBBH(X3σ) Radical in Neon and Argon Matrices at 4 K. Comparison with ab Initio SCF and CI Calculations.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.