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The low-lying electronic transitions of the neptunyl(NpO22+) ion are characterized as either chargetransfer (CT)or intra- 5f. Comparison of these classes of electronic transitionsreveals significantly different photophysical properties, especiallyin vibronic coupling. An empirical model developed for analyses ofuranyl CT vibronic transitions is used here to simulate the absorption(excitation) spectra of neptunyl in two compounds of different chemicalcompositions and structural symmetries. Analyses reveal that CT vibroniccoupling in neptunyl has the same characteristics as that in typicaluranyl analogues. The primary profile of the CT spectra is similarfor neptunyl respectively with respect to chloride- and oxide-neptuniumbonding interactions. On the other hand, vibronic coupling to theCT transitions is significantly different from that of f-f transitions,even within a given neptunyl compound. Electronic energy levels, vibroniccoupling strength, and frequencies of various vibration modes wereevaluated for transitions to the excited states of different originsin the region from 8000 cm–1to 21000 cm–1for two neptunyl compounds. [ABSTRACT FROM AUTHOR]

U(VI), Np(VI), and Pu(VI) borates with the formula AnO2[B8O11(OH)4] (An = U, Np, Pu) have been prepared via the reactions of U(VI) nitrate, Np(VI) perchlorate, or Pu(IV) or Pu(VI) nitrate with molten boric acid. These compounds are all isotypic and consist of a linear actinyl(VI) cation, AnO22+, surrounded by BO3 triangles and BO4 tetrahedra to create an AnO8 hexagonal bipyramidal environment. The actinyl bond lengths are consistent with actinide contraction across this series. The borate anions bridge between actinyl units to create sheets. Additional BO3 triangles and BO4 tetrahedra extend from the polyborate layers and connect these sheets together to form a three-dimensional chiral framework structure. UV-vis-NIR absorption and fluorescence spectroscopy confirms the hexavalent oxidation state in all three compounds. Bond-valence parameters are developed for Np(VI). [ABSTRACT FROM AUTHOR]

Four new uranyl borates, Li[UO2B5O9]·H2O (LiUBO-1), Ag[(UO2)B5O8(OH)2] (AgUBO-1), α-Cs[(UO2)2B11O16(OH)6] (CsUBO-1), and β-Cs[(UO2)2B11O16(OH)6] (CsUBO-2) were synthesized via the reaction of uranyl nitrate with a large excess of molten boric acid in the presence of lithium, silver, or cesium nitrate. These compounds share a common structural motif consisting of a linear uranyl, UO22, cation surrounded by BO3triangles and BO4tetrahedra to create an UO8hexagonal bipyramidal environment around uranium. The borate anions bridge between uranyl units to create sheets. Additional BO3triangles extend from the polyborate layers, and are directed approximately perpendicular to the sheets. In Li[(UO2)B5O9]·H2O, the additional BO3triangles connect these sheets together to form a three-dimensional framework structure. Li[UO2)B5O9]·H2O and β-Cs[(UO2)2B11O16(OH)6] adopt noncentrosymmetric structures, while Ag[(UO2)B5O8(OH)2] and α-Cs[(UO2)2B11O16(OH)6] are centrosymmetric. Li[(UO2)B5O9]·H2O, which can be obtained as pure phase, displays second-harmonic generation of 532 nm light from 1064 nm light. Topological relationships of all actinyl borates are developed. [ABSTRACT FROM AUTHOR]

A new neutral borate species, H2B4O7 (also known as tetraboric acid), with a one-dimensional chain structure, is found in the interlayer spacing in Rb2[(UO2)2B8012F6].H2B4O7 (RbUBOF-2) derived from boric acid flux reaction of uranyl(Vl) nitrate with RbBF4. This new form of tetraboric acid possesses a novel borate fundamental building block with the symbol 4Δ:(3Δ)Δ. [ABSTRACT FROM AUTHOR]

The boric acid flux reaction of N

A new neptunium(V) borate, K[(NpO2)B10O14 (OH) 4], was synthesized using boric acid as a reactive flux. The compound possesses a layered structure in which NpV resides in triangular holes, creating a hexagonal-bipyramidal environment around neptunium. This compound is unusual in that it exhibits the Alexandrite effect, a property that is typically restricted to neptunium(IV) compounds. [ABSTRACT FROM AUTHOR]

A Np(V) compound containing three-center cation-cation interations, K(NpO2)3(H2O)Cl4, has been prepared by reacting Np(V) with KCl in molten boric acid. This compound forms a three-dimensional channel structure that is constructed from both two- and three-center cation-cation interactions. Three new bonding modes for cation-cation interactions are added to the summary of all known Np(V) compounds. [ABSTRACT FROM AUTHOR]

The first plutonium(III) borate, Pu2[B12O18(OH)4Br2(H2O)3]·0.5H2O, has been prepared by reacting plutonium(III) with molten boric acid under strictly anaerobic conditions. This compound contains a three-dimensional polyborate network with triangular holes that house the plutonium(III) sites. The plutonium sites in this compound are 9- and 10-coordinate and display atypical geometries. [ABSTRACT FROM AUTHOR]

A radiochemistry laboratory presents potential radiological hazards due to the handling of multiple radionuclides with various half-lives and modes of radiation emission. To minimize these hazards, appropriate safety management and radiation protection strategies should be in place. The radiochemistry laboratory at Soochow University is one such workplace that handles therapeutic radionuclides, fission products, and actinides in liquid, solid, and gas forms. This work highlights the significance of using safety precautions and radiation protection strategies before conducting experiments in such laboratories. The practical knowledge gained from a case of radioactive contamination is discussed to provide valuable experience for safely conducting radiochemistry experiments. [ABSTRACT FROM AUTHOR]

Uranium is not only a strategic resource for the nuclear industry but also a global contaminant with high toxicity. Although several strategies have been established for detecting uranyl ions in water, searching for new uranium sensor material with great sensitivity, selectivity, and stability remains a challenge. We introduce here a hydrolytically stable mesoporous terbium(III)-based MOF material compound 1, whose channels are as large as 27 Å × 23 Å and are equipped with abundant exposed Lewis basic sites, the luminescence intensity of which can be efficiently and selectively quenched by uranyl ions. The detection limit in deionized water reaches 0.9 µg/L, far below the maximum contamination standard of 30 µg/L in drinking water defined by the United States Environmental Protection Agency, making compound 1 currently the only MOF material that can achieve this goal. More importantly, this material exhibits great capability in detecting uranyl ions in natural water systems such as lake water and seawater with pH being adjusted to 4, where huge excesses of competing ions are present. The uranyl detection limits in Dushu Lake water and in seawater were calculated to be 14.0 and 3.5 µg/L, respectively. This great detection capability originates from the selective binding of uranyl ions onto the Lewis basic sites of the MOF material, as demonstrated by synchrotron radiation extended X-ray adsorption fine structure, X-ray adsorption near edge structure, and first principles calculations, further leading to an effective energy transfer between the uranyl ions and the MOF skeleton. [ABSTRACT FROM AUTHOR]