Research progress of SERS on uranyl ions and uranyl compounds: A review

There is an urgent demand for rapid and sensitive analysis of uranyl ions and uranyl compounds in the environmental monitoring and nuclear emergency fields. However, most of the current analytic...

Topological analysis of the layered uranyl compounds bearing slabs with UO2:TO4 ratio of 2:3

Nine new templated uranyl sulfates and selenates, [(H9O4)2(H2O)][(UO2)2(SO4)3(H2O)2] (H9US), [(C5H7 NO)2(H2O)][(UO2)2(SeO4)3(H2O)2](H2O) (OUSe), [C6H6N3][H5O2] [(UO2)2(SeO4)3(H2O)] (BH5USe), [C6H6N3][H7O3][(UO2)2(SO4)3 (H2O)](H2O) (BH7US), [C6H16N][H5O2][(UO2)2(SeO4)3(H2O)] (TeH5USe), [C6H18N2][(UO2)2(SO4)3(H2O)] (TmUS), [H5O2]2 [(UO2)2(SeO4)3(H2O)](H2O) (H5USe-1), [H5O2]2[(UO2)2(SeO4)3 (H2O)2](H2O)9 (H5USe-2), and [C4H14N2][(UO2)2(SeO4)3(H2O)](H2O) (DmUSe) have been prepared by isothermal evaporation of aqueous solutions containing extra sulfuric or selenic acid. Their crystal structures can be considered as organo-inorganic hybrids constructed of alternating [(UO2)2 (TO4)3(H2O)n]2− slabs (T = Se6+, S6+, n = 1, 2) and layers containing templating organic moieties and/or hydronium ions and water molecules. The organic and inorganic parts of the structures are linked by multiple hydrogen bonds. Besides structure description, we offer topological analysis of the inorganic fragments with UO2:TO4 ratio of 2:3 as modular units resulting from self-assembly of fundamental chains formed by [(UO2)2(TO4)2] tetramers and TO4 tetrahedra.

Dimensional evolution in hydrated K+-bearing uranyl sulfates: from 2D-sheets to 3D-frameworks

Six new uranyl compounds were synthesized within the K+-bearing uranyl sulfate system. An unexpected example of dimensional evolution is demonstrated.

Effect of solution acidity on the structure of amino acid-bearing uranyl compounds

A series of uranyl sulfates and selenates templated by protonated forms of amino acids (glycine, α- and β-alanine, threonine, nicotinic, and isonicotinic acid) has been prepared via isothermal evaporation of strongly acidic solutions. Their structures have been refined by the direct methods and can be classified as inorganic [(UO2)m(TO4)n (H2O)k] (T=S6+, Se6+) moieties combined with the protonated amino acid cations, water molecules and hydronium ions. Their overall motifs demonstrate common features with related structures templated by organic amines. The role of carboxylic acid groups depends on the nature of the corresponding amino acid. They can either link two protonated organic moieties into dimers, or contribute to hydrogen bonding between organic and inorganic parts of the structure. The ammonium ends of the amino acid cations form strong directional bonds to the oxygens of the uranyl and TO4 anions.

Зондовая спектроскопия комбинационного рассеяния света поликристаллов ураниловых соединений

Regularities in the Raman spectra of acetate uranyl compounds CsUO_2(CH_3COO)_3, CsUO_2(CD_3COO)_3, NaUO_2(CH_3COO)_3, NaUO_2(CD_3COO)_3, UO_2(CH_3COO)_2, and RbUO_2(CH_3COO)_3 have been analyzed. The Raman spectra are excited by 785-nm laser radiation and recorded using a miniature fiber-optic spectrometer with a multielement detector. It is established that the spectra of all these compounds contain a strong Raman satellite with a frequency in the range of 850–860 cm^–1. This satellite corresponds to symmetric stretching vibrations (type A _1) of the uranyl group. The obtained results make it possible to detect and analyze small amounts of uranyl compounds.

Complex Uranyl Dichromates Templated by Aza-Crowns

Three new uranyl dichromate compounds templated by aza-crown templates were obtained at room temperature by evaporation from aqueous solutions: (H2diaza-18-crown-6)2[(UO2)2(Cr2O7)4(H2O)2](H2O)3 (1), (H4[15]aneN4)[(UO2)2(CrO4)2(Cr2O7)2(H2O)] (H2O)3.5 (2) and (H4Cyclam)(H4[15]aneN4)2[(UO2)6(CrO4)8(Cr2O7)4](H2O)4 (3). The use of aza-crown templates made it possible to isolate unprecedented and complex one-dimensional units in 2 and 3, whereas the structure of 1 is based on simple uranyl-dichromate chains. It is very likely that the presence of relatively large organic molecules of aza-crown ethers does not allow uranyl chromate chain complexes to condense into the units of higher dimensionality (layers or frameworks). In general, the formation of 1, 2, and 3 is in agreement with the general principles elaborated for organically templated uranyl compounds. The negative charge of the [(UO2)(Cr2O7)2(H2O)]2−, [(UO2)2(CrO4)2(Cr2O7)2(H2O)]4− and [(UO2)3(CrO4)4(Cr2O7)2]6− one-dimensional inorganic motifs is compensated by the protonation of all nitrogen atoms in the molecules of aza-crowns.