Search results for "uranyl"

Efficiency of dihydroxamic and trihydroxamic siderochelates to extract uranium and plutonium from contaminated soils

2021

International audience; Actinide-based mineral phases occurring in contaminated soils can be solubilized by organic chelators excreted by plants, such as citrate. Herein, the efficiency of citrate towards U and Pu extraction is compared to that of siderophores, whose primary function is the acquisition of iron(III) as an essential nutrient and growth factor for many soil microorganisms. To that end, we selected desferrioxamine B (DFB) as an emblematic bacterial trishydroxamic siderophore and a synthetic analog, abbreviated (LCy,Pr)H2, of the tetradentate rhodotorulic acid (RA) produced by yeasts. Firstly, the uranyl speciation with both ligands was assessed in the pH range 2–11 by potentiom…

CCDC 137392: Experimental Crystal Structure Determination

2001

Related Article: S.Mahboobi, M.Koller, D.Schollmeyer|2000|Monatsh.Chem.|131|383|doi:10.1007/s007060050319

CCDC 170821: Experimental Crystal Structure Determination

2002

Related Article: S.Arndt, A.Trifonov, T.P.Spaniol, J.Okuda, M.Kitamura, T.Takahashi|2002|J.Organomet.Chem.|647|158|doi:10.1016/S0022-328X(01)01421-8

Advances in the investigation of dioxouranium(VI) complexes of interest for natural fluids

2012

Abstract The interactions of dioxouranium(VI) cation with different organic and inorganic ligands of environmental and biological interest were carefully examined with the aim to draw a chemical speciation picture of this ion in natural aquatic ecosystems and in biological fluids. Since UO22+ ion shows a significant tendency to hydrolyze, particular attention was paid in considering the hydrolysis species formation both in the presence and in absence of ligands. The results reported in the literature show that formation of the hydrolytic species assumes a great importance in the complexation models for all the UO22+-ligand systems considered. In particular, the following ligands have been t…

Interaction of UO2(2+) with ATP in aqueous ionic media.

2005

Interaction of dioxouranium(VI) (uranyl) ion with ATP was studied by ligand/proton and metal/hydroxide displacement technique, at very low ionic strength and at I=0.15 mol L(-1), in aqueous Me4NCl and NaCl solutions, at t=25 degrees C. Measurements were carried out in the pH range 3-8.5, before the formation of precipitate. Computer analysis allowed us to find the quite stable species UO2(ATP)H2(0), UO2(ATP)H-, UO2(ATP)2-, UO2(ATP)2(6-), UO2(ATP)2H2(4-) and UO2(ATP)(OH)3- whose formation constants are (at I=0 mol L(-1)) logbeta(112)=18.21, logbeta(111)=14.70, logbeta(110)=9.14, logbeta(120)=12.84, logbeta(122)=24.82, and logbeta(11-1)=2.09, respectively. Different values were obtained in th…

A density functional theory study of uranium(VI) nitrate monoamide complexes.

2011

Density functional theory calculations were performed on uranyl complexed with nitrate and monoamide ligands (L) [UO(2)(NO(3))(2)·2L]. The obtained results show that the complex stability is mainly governed by two factors: (i) the maximization of the polarizability of the coordinating ligand and (ii) the minimization of the steric hindrance effects. Furthermore, the electrostatic interaction between ligands and uranium(vi) was found to be a crucial parameter for the complex stability. These results pave the way to the definition of (quantitative) property/structure relationships for the in silico screening of monoamide ligands with improved extraction efficiency of uranium(vi) in nitrate ac…

Ion Pair Recognition of Quaternary Ammonium and Iminium Salts by Uranyl-Salophen Compounds in Solution and in the Solid State

2007

Efficient ditopic receptors for quaternary ammonium and iminium salts have been obtained upon functionalization of the uranyl-salophen unit with conformationally flexible side arms bearing phenyl or beta-naphthyl substituents. Binding affinities in chloroform solution have been measured for a large number of quaternary salts comprising tetramethylammonium (TMA), tetrabutylammonium (TBA), acetylcholine (ACh), N-methylpyridinium (NMP), and N-methylisoquinolinium (NmiQ) cations. Recognition of the anion partner is ensured by coordination to the hard Lewis acidic uranyl center, whereas cation-pi/CH-pi interactions of the quaternary ions are established with the aromatic pendants. The role of th…

Interactions UO22+ - amines

2007

Solution and solid-state studies on the halide binding affinity of perfluorophenyl-armed uranyl–salophen receptors enhanced by anion–π Interactions

2016

The enhancement of the binding between halide anions and a Lewis acidic uranyl-salophen receptor has been achieved by the introduction of pendant electron- deficient arene units into the receptor skeleton. The association and the occurrence of the elusive anion-p interaction with halide anions (as tetrabutylammonium salts) have been demonstrated in solution and in the solid state, providing unambiguous evidence on the interplay of the concerted interactions responsible for the anion binding.

Uranyl sorption onto birnessite: A surface complexation modeling and EXAFS study

2014

This work investigates the mechanism of the uranyl interaction with birnessite, one of the most common layer-type MnO2 mineral at the Earth's surface, by coupling macroscopic (surface complexation experiments) and microscopic (EXAFS measurements) approaches. The sorption of uranyl on synthetic hexagonal birnessite, the low-pH birnessite form, was studied under various conditions of pH (3–6), electrolyte backgrounds (0.1 M NaClO4, NaNO3 and Na2CO3), and solid/liquid ratios (from 0.27 to 4.5 g/L). Sorption isotherms exhibit a complex form indicative of at least two types of sorption sites. EXAFS data reveal the presence of two equatorial O shells at ca. 2.32 Å and 2.46 Å for all the samples, …