Four new open-framework alkali metal uranyl silicates, Rb4(UO2)2(Si8O20) (USH-2Rb), Rb2(UO2)(Si2O6)?H2O (USH-4Rb), and A2(UO2)(Si2O6)?0.5H2O (USH-5A; A ~ Rb, Cs), have been prepared hydrothermally at 245 uC. The structures of USH-2, -4, and -5 contain UO6 tetragonal bipyramidal units connected by double chains, 4-membered rings, and single chains of SiO4 tetrahedra, respectively. The compounds ...

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Crystals of four sodium uranyl molybdates, Na3Tl3[(UO2)(MoO4)4] (1), Na13–xTl3+x[(UO2)(MoO4)3]4(H2O)6+x (x = 0.1) (2), Na3Tl5[(UO2)(MoO4)3]2(H2O)3 (3) and Na2[(UO2)(MoO4)2](H2O)4 (4), have been synthesized by hydrothermal methods. The structure of each was solved and refined on the basis of F2 for all unique data collected using MoK X-radiation and a CCD-based detector. The structure of 1 [orth...

The coordination environment of uranyl in water has been studied using a combined quantum mechanical and molecular dynamics approach. Multiconfigurational wave function calculations have been performed to generate pair potentials between uranyl and water. The quantum chemically determined energies have been used to fit parameters in a polarizable force field with an added charge transfer term. ...

Nuclear weapons and fuel production have left many soils and sediments contaminated with toxic levels of uranium (U). Although previous short-term experiments on microbially mediated U(VI) reduction have supported the prospect of immobilizing the toxic metal through formation of insoluble U(IV) minerals, our longer-term (17 months) laboratory study showed that microbial reduction of U can be tr...

The complexation of uranyl ions with lipopolysaccharide (LPS), the main component of the cell wall of Gram-negative bacteria, was investigated on a molecular level with U L(III)-edge extended X-ray absorption fine structure (EXAFS) and attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy over a wide pH range (2.6 to 7.0). For the first time, structural determinations ...

The multiwavelength anomalous diffraction (MAD) method for phase evaluation is now widely used in macromolecular crystallography. Successful MAD structure determinations have been carried out at the K or L absorption edges of a variety of elements. In this study, we investigate the anomalous scattering properties of uranium at its M(IV) (3.326 A) and M(V) (3.490 A) edge. Fluorescence spectra sh...