Xenon und Krypton

Ohne Zusammenfassung     

气相色谱法测定大气中氪和氙

设计了一套测定气体的可调压进样装置,提出了气相色谱法-脉冲放电氦离子化检测器测定大气中氪和氙的含量。通过采用低温分离、柱程序升温及高效吸气柱消除了样品中基体气体对氪、氙测定的干扰。氪和氙的检出限(3S/N)分别为11 pg和24 pg。     

Die quantitative Trennung von Krypton und Xenon im Trennrohr

Ohne Zusammenfassung     

Preparation and Properties of Inclusion Compounds of Cyclodextrins with Organotransition Metal Complexes

Inclusion compounds of transition metal complexes of cycloocta-1,5-diene (cod) and norbornadiene (nbd) with cyclodextrins were prepared. Two-to-one (cyclodextrin:guest) inclusion compounds were obtained in high yields by the treatment of β-cyclodextrin (β-CD) with [(L)RhCl]₂ (L = nbd or cod) and 1:1 inclusion compounds were obtained by the reaction of β-CD with (cod)PtX₂ (X = Cl, Br, or I) in high yields, while γ-CD formed 1:1 inclusion compounds with (cod)PtX₂ (X = Br or I). The formation of inclusion compounds is selective. α-CD did not form inclusion compounds with any transition-metal complexes with cycloocta-1,5-diene. Thermogravimetric measurements show that the complexes are stabilized by inclusion in cyclodextrin cavities. The inclusion compounds were characterized by ¹ H-NMR, IR, UV, and circular dichroism spectra.     

Structures of Xenon Oxygen Compounds

The structure of long known Xe(OTeF₅)₄ is established by x-ray crystallography. The xenon atom is surrounded by four equidistant oxygen atoms in a square planar manner. O₂Xe(OTeF₅)₂ is formed according to OXe(OTeF₅)₄ → O₂Xe(OTeF₅)₂ + F₅TeOTeF₅, Its structure, again established by x-ray crystallography, shows a very distorted tetrahedral or pseudo-trigonal bipyramidal xenon environment. The electron pair repulsion models fails here in explaining the details of this geometry.     

A Novel Fluorinated Metal-organic Framework for Xenon/Krypton Separation

A porous metal-organic framework[C21H20CoF6O7]was synthesized with Co(CH3 COO)2·4 H2 O and CPHFP(2,2’-bis(4-carboxyphenyl)hexafluoro-propane)under hydrothermal conditions.This FMOF-Co has been characterized by elemental analysis,infrared spectroscopy,thermogravimetric analysis,single-crystal and powder X-ray diffraction.The crystal is of monoclinic space group P21/n with a=7.8911(2),b=29.9053(8),c=10.5811(3)?,β=90.193(10)°,V=2499.70(12)?³,Z=4,M_r=557.3,D_c=1.481 g·cm^–3,F(000)=1132,μ=0.768 mm^–1,GOOF=1.035,the final R=0.0722 and w R=0.2326 for 6347 observed reflections with I>2σ(I).The structure of FMOF-Co is constructed form the linkage of Co(II)through CPHFP,forming a 3 D net framework.The Kr and Xe uptake values are 0.225 and 0.484 mmol·g^–1 at 303 K(100 KPa)with their mol selectivity to be 0.46;while the Kr and Xe uptake values are 0.486 and 0.077 mmol·g^–1 at 233 K(100 KPa),with their mol separation being 6.29 at this condition.     

Structure and Density Comparison of Noble Gas Hydrates Encapsulating Xenon,Krypton and Argon

Understanding the effect of guest species on the host framework is important for the development of structure-based properties of inclusion compounds. Herein, the crystal structures of the noble gas hydrates encapsulating Xe, Kr, and Ar were studied by powder X-ray diffraction measurements. The crystal structures and hydration numbers of these noble gas hydrates were solved by Rietveld refinements using optimized models with the direct-space technique. It was revealed that host cage size of these hydrates changed depending on the type of guest species even though their unit-cell parameters were the same. Based on the structure models obtained, the densities of Xe, Kr, and Ar gas hydrates were also determined to be 1.837, 1.445 and 1.097 g/cm³ at 93 K, respectively. Our findings, from a crystallographic point of view, may give insight into further understanding the thermodynamic stability and physical properties of gas hydrates encapsulating small guests.     

直接进样气相色谱-质谱法分析大气中的氪和氙

大气中氪和氙体积比浓度的测量对于氪-85和放射性氙同位素监测具有重要意义。本实验设计了一套集成定量稀释功能的可调样量进样装置,对质谱检测器的工作参数进行了实验优化,确定了灯丝电离能量70 eV、灯丝发射电流40 mA、推斥极电压27 mV、离子聚焦电压85 mV和透镜补偿电压20 V等最佳工作条件。建立了空气样品直接进样条件下氪和氙的气质联用分析方法,氪和氙的最低可检测浓度分别为3.3×10-8(V/V)和2.6×10-9(V/V)。同时应用本方法测量了实验室所处开放空间大气中氪和氙的体积比浓度,分别为1.1×10-6(V/V)和9.3×10-8(V/V),相对合成标准不确定度分别为2.38%和3.15%。     

可燃"冰"与包合物

可燃"冰"是一种沉睡海底和高寒冻土地带待开发的能源.它储存量大,含能量高,是甲烷类中性分子生成的气体水合物,是一类广泛存在的包合物.这种类型包合物的极限化学式为8X@46H2O.本文就可燃"冰"的发现史、结构特点等辐射到的相关知识做一简单介绍.     

Sorption and Desorption of Inclusion Compound Guests Different Types of Inclusion Compounds

The guests present in inclusion compounds participate in bonding with the hosts. The conditions for the sorption and desorption of the guests are decisive for the properties of the inclusion compounds. They are surveyed for many types of inclusion compounds. This revised version was published online in August 2006 with corrections to the Cover Date.     

Hydrogen-Bonding Assembly Meets Anion Coordination Chemistry: Framework Shaping and Polarity Tuning for Xenon/Krypton Separation

Hybrid hydrogen-bonded (H-bonded) frameworks built from charged components or metallotectons offer diverse guest-framework interactions for target-specific separations. We present here a study to systematically explore the coordination chemistry of monovalent halide anions, i.e., F⁻, Cl⁻, Br⁻, and I⁻, with the aim to develop hybrid H-bond synthons that enable the controllable construction of microporous H-bonded frameworks exhibiting fine-tunable surface polarity within the adaptive cavities for realistic xenon/krypton (Xe/Kr) separation. The spherical halide anions, especially Cl⁻, Br⁻, and I⁻, are found to readily participate in the charge-assisted H-bonding assembly with well-defined coordination behaviors, resulting in robust frameworks bearing open halide anions within the distinctive 1D pore channels. The activated frameworks show preferential binding towards Xe (IAST Xe/Kr selectivity ca. 10.5) because of the enhanced polarizability and the pore confinement effect. Specifically, dynamic column Xe/Kr separation with a record-high separation factor (SF=7.0) among H-bonded frameworks was achieved, facilitating an efficient Xe/Kr separation in dilute, CO₂-containing gas streams exactly mimicking the off-gas of spent nuclear fuel (SNF) reprocessing.     

A New Functional Cyclophane Host. Synthesis, Complex Formation and Crystal Structures of Three Inclusion Compounds

A new macrocyclic host compound 2 having an octamethylsubstituted cyclophane structure with two intra-annular carboxylic acid functions has beensynthesized. The properties of crystalline inclusion formation are studied and X-ray crystalstructures of three inclusion complexes including acetic acid, propionic acid and acetone asthe guest molecules are reported. Inter-host channel formation with complexed guest moleculesaccommodated into the channels are typical features of the acetic acid and acetone 1 : 4 (host : guest) stoichiometric complexes being also hydrated species, while the propionicacid 1 : 2 complex is of the close packing type containing no additional water molecules.Systems of hydrogen bonds involving the host and guest functional groups are common toall structures. In the case of the acetic acid inclusion compound, a complex supramolecularhydrogen-bonded array comprising a bordering tricyclic assembly of eight molecular species exists.     

Triarylmethanol Host Compounds. Synthesis, Crystalline Complex Formation and X-Ray Crystal Structures of Three Inclusion Species

A variety of triarylmethanol compounds including benzo condensed and laterally substituted derivatives 1–10 have been prepared and shown to act as crystallinehosts for the inclusion of organic solvents involving protic polar, aprotic dipolar and apolar molecules. The inclusion ability is ratherhigh for aprotic dipolar solvents while protic polarcompounds are only rarely enclathrated. Host 9 is an exception, being also efficient with alcohols and amines. Compound3 displays no inclusion formation under theexperimental conditions. X-ray crystal structures of the inclusion compound 1acetone (2:1) and of two amineinclusion compounds of host 9 [9 n-propylamine(1:1), 9di-n-propylamine (1:1)] are reported showing the formation of H-bondedhost-guest associates as the common feature of supramolecular association.Supplementary data relating to this article have beendeposited with the British Library, No. SUP 82226 (10 pages).at Boston Spa, Wetherby, West Yorkshire, U.K., as Supplementary Publication.     

Cyclodextrin Inclusion Compounds in Research and Industry

α-, β-, and γ-Cyclodextrins are cyclic oligosaccharides consisting of six, seven, or eight glucose units, which can be obtained on a large scale from starch. They form inclusion compounds with smaller molecules which fit into their 5—8 Å cavity. These (crystalline) complexes are of interest for scientific research as, contrary to the classical clathrates, they exist in aqueous solution and can be used to study the hydrophobic interactions which are so important in biological systems. Cyclodextrins also serve as models both for polymeric starch and, in the form of their polyiodide complexes, for “blue iodine-starch”. As cyclodextrins catalyze several chemical reactions they and their functionalized derivatives provide useful enzyme models. Cyclodextrins can be used to advantage in the production of pharmaceuticals, pesticides, foodstuffs, and toilet articles—the (micro-encapsulated) active and aromatic substances enclosed within them are protected from the effects of light and atmosphere and can be easily handled and stored in powder from. Substances which are not very soluble in water become more soluble in the presence of cyclodextrins—creams and emulsions can be stabilized, and the growth and yield of grain harvests can be increased. Cyclodextrins can be chemically modified for many different purposes; polymerized cyclodextrin or cyclodextrin bound to a polymer carrier have already been employed in gel inclusion and affinity chromatography.     

含硅金属化合物

近年来,含硅金属化合物由于在催化工业等领域的广泛应用受到了化学工作者的重视.本文综述了以硅原子或硅杂链为配体的桥形成的金属络合物、金属硅氧烷、硅-金属化合物、金属不饱和硅化物和含硅多金属络合物5种含硅金属化合物的研究进展,并对该领域的研究方向提出了展望.     

环糊精与聚合物的包合作用

本文着重介绍了环糊精及其衍生物与聚合物所形成的各种包合物,并扼要介绍了它们的研究和应用前景。     

Inclusion Compounds of Bulky Binaphthyl-type Bis-fluorenol Hosts

Inclusion properties of a new family of clathrate hosts (1–4) containing two 9-hydroxy-9-fluorenyl units or chloro-, bromo- and t-butyl-substituted derivatives of this group attached in the 3,3′-position to a basic 2,2′-binaphthyl construction element are reported (115 examples of clathrates). The crystal structures of six selected clathrates, involving dimethylsulfoxide, cyclopentanol, diethylether, benzylamine, chloroform and acetone as the guest, have been determined by X-ray diffraction, showing varied modes of supramolecular interaction dependent on the host and guest constitutions, while the formation of an intramolecular hydrogen bond between the hydroxy groups of the fluorenol units is a common structural feature (except in 3a) controlling twisted conformation of the host molecules.