Uranocenium: Synthesis,Structure, and Chemical Bonding

Abstraction of iodide from [(η⁵‐C₅ⁱPr₅)₂UI] ( 1 ) produced the cationic uranium(III) metallocene [(η⁵‐C₅ⁱPr₅)₂U]⁺ ( 2 ) as a salt of [B(C₆F₅)₄]^?. The structure of 2 consists of unsymmetrically bonded cyclopentadienyl ligands and a bending angle of 167.82° at uranium. Analysis of the bonding in 2 showed that the uranium 5f orbitals are strongly split and mixed with the ligand orbitals, thus leading to non‐negligible covalent contributions to the bonding. Investigation of the dynamic magnetic properties of 2 revealed that the 5f covalency leads to partially quenched anisotropy and fast magnetic relaxation in zero applied magnetic field. Application of a magnetic field leads to dominant relaxation by a Raman process.     

低浓度下的仿生矿化及其在对映体拆分中的应用

以L-苯丙氨酸衍生物(L-18Phe6PyBr)的自组装体为模板, 在0.30 mmol/L的浓度下, 研究了pH值、 老化时间和四乙氧基硅烷(TEOS)浓度对二氧化硅形貌的影响. 通过扫描电子显微镜和透射电子显微镜对样品进行表征. 结果表明, 在pH=10.01的条件下可以得到左手扭转的纳米带, 而pH=7.15和12.34时, 得到直线的纳米带. 遵循动态模板的方法, 老化时间的延长有利于直线纳米带的形成. 随着TEOS和L-18Phe6PyBr的质量比由2:1增加到15:1, 扭转纳米带的宽度增加, 螺距变长. 通过煅烧除去有机模板后, 得到带状二氧化硅纳米管. 将TEOS与L-18Phe6PyBr质量比为2:1制备得到的二氧化硅作为气相色谱固定相, 涂渍到毛细管色谱柱中进行对映体拆分. 结果表明, 该气相色谱柱可以拆分1-苯基-1-丙醇、 1-(4-氯苯基)乙醇和2-甲基戊酸3种外消旋化合物, 手性超分子印迹是拆分对映体的主要作用力. 对二氧化硅低聚物与小分子凝胶的协同组装行为以及将无机材料作为手性固定相有了一个更好的认识.     

SIMS Analysis of Uranium and Actinides in Microparticles of Different Origin

In the framework of the projects Environmental Sampling and High Performance Trace Analysis in support to the International Atomic Energy Agency (IAEA) and the Euratom Safeguards Office (ESO), the research has been focused on the identification and characterisation of particles of interest containing mainly U and other actinides.Multiple analyses, elemental and isotopic, of single radioactive particles in the µm-size range are key-tools in environmental research and in nuclear forensics. The main purpose in the analysis of single particles by SIMS is the determination of their isotopic composition that has been demonstrated successfully for uranium and plutonium particles. From these results, the enrichment of the material produced, the process used for the enrichment as well as the starting material employed (natural or reprocessed uranium) can be identified.     

2-(2-喹啉偶氮)-5-二甲氨基苯酚光度法测定铀的研究

铀的测定一般采用铀试剂-Ⅲ或5-Br-PADAP光度法。2-喹啉偶氮类试剂已用于一些金属离子的测定,由于其共轭体系大,比吡啶偶氮类试剂具有更高的灵敏度。我们合成了2-(2-喹啉偶氮)-5-二甲氨基苯酚(QADMAP),产品经IR,MS及^1H NMR表征(谱图略)。研究其和铀的显色反应,建立了一种测定矿石中铀的方法。     

Simple route to secondary amides of phosphorylacetic acids and their use for extraction and sorption of actinides from nitric acid solutions

An efficient method for the synthesis of secondary alkylamides of phosphorylacetic acids (APA) was proposed. The method involves amidation of ethyl phosphorylacetates with primary aliphatic amines. The scope of reaction was determined. Reactions with ethylenediamine and 1,4-diaminobutane yield the corresponding bisamides; in the case of 1,3-diaminopropane, N-(3-aminopropyl)diphenylphosphorylacetamide or N,N-propylenebis(diphenylphosphorylacetamide) was obtained, depending on the reaction conditions. The extraction of americium(III) complexes and the sorption of uranium(VI) by sorbents with physically sorbed APA from nitric acid solutions were studied. There is no correlation between the partition coefficient of americium(III) and the structure of APA; in the sorption of uranium(VI), the degree of extraction depends on the complexone structure.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2394–2402, November, 2004.     

可剥离膜去除不锈钢表面铀污染的研究

退役的核设施中不锈钢制件表面附着的放射性污染物 ,必须经去污处理后才能回收利用。铀是核工业中最常见的污染放射性元素 ,而不锈钢是核设施中最常用的耐腐蚀金属材料 ,由于以ＵＯ2 +2 状态存在的铀 (Ⅵ ) ,在空气和自身的辐射作用下 ,将逐渐转变为不同的氧化物。采用酸性去污液对不锈钢表面铀污染进行浸泡和擦试去污的方法 ,可以有效的除去不锈钢表面铀污染[1] 。但因浸泡需大量的去污液 ,随之产生大量的带有放射性的废液 ,对这些废液还必须经进一步的浓缩———固化处理。擦试法虽产生固体废物 ,但去污操作麻烦 ,难以对大批量、形状复杂…     

Complexing Properties of Uranium and Lanthanoids With 4-(2-Thiazolylazo)-6-Chlororesorcinol

Abstract

4-(2-Thiazolylazo)-6-chlororesorcinol (TAR-Cl) reacts sensitively with uranyl(II) and lanthanoids(III), and forms reddish-brown 1:1 and 1:2 complexes. The complexing behaviors were examined spectrophotometrically. The absorption maxima of the complexes are focused near 553 nm and the optimum pH for complexation lies between 6.5–8.8. Beer's law holds up to about 2 × 10^?5 mol 1^?1, with a molar absorptivity of 3.00 × 10⁴ 1 mol^?1 cm^?1 for uranium and 6 × 10⁴ 1 mol^?1 cm^?1 level for each lanthanoid. The absorptivities are increased with the atomic number, especially in light lanthanoids, that are correlative both to the lanthanoid contraction and the basicity of ortho hydroxyl group in the resorcinol ring, but such effects are not clearly recognized in heavy lanthanoids. Effect of masking agents was also examined, and uranium could be determined selectively in the presence of lanthanoid mixtures by the addition of CyDTA.     

Discovery of powerful uranyl ligands from efficient synthesis and screening

New tripodal gem-(bis-phosphonates) uranophiles were discovered by a screening method that allowed for the selection of ligands with strong uranyl-binding properties in a convenient microtiter-plate format. The method is based on competitive uranium binding by using Sulfochlorophenol S as chromogenic chelate. This dye compound was found to present high uranyl complexation properties and allowed to highlight ligands presenting association constants for UO(2+)(2) up to 10(18) at pH 7.4 and 10(20) at pH 9. A collection of 40 known ligands including polycarboxylate, hydroxamate, catecholate, hydroxypyridonate and hydroxyquinoline derivatives was tested. Also screened was a combinatorial library prepared from seven amine scaffolds and eight acrylates bearing diverse chelating moieties. Among these 96 tested candidates, a tripod derivative bearing gem-bis-phosphonates moieties was found to present the highest complexation properties over a wide range of pH and was further studied.     

[U(CO_3)_3(H_2O)_2]·2H_2O配合物的合成及晶体结构

A uranylcontaining compound [U(CO_3)_3(H_2O)_2]·2H_2O has been synthesized under hydrothermal condition and characterized by X-ray single-crystal analysis. Crystal structural analysis indicates that this compound consists of three CO_3~(2-) molecules, one U~(6+). The results reveal that the title compound presents a 3D frame work built up by O-H……O week hydrogen bonds interactions. The central uranium atom is eight-coordinated through three CO_3~(2-) molecules and two H_2O. The compound shows a coplanar hexagonal network structure, each hexagon containing a hexagonal hole with a water moleculet.