Density functional study of uranyl （VI） amidoxime complexes

Uranyl （VI） amidoxime complexes are investigated using relativistic density functional theory. The equilibrium structures, bond orders, and Mulliken populations of the complexes have been systematically investigated under a generalized gradient approximation （GGA）. Comparison of （acet） uranyl amidoxime complexes （[UO2（AO）n]2-n, 1≤ n≤4） with available experimental data shows an excellent agreement. In addition, the U-O（1）, U-O（3）, C（1）-N（2）, and C（3） N（4） bond lengths of [UO2（CH3AO）4]2- are longer than experimental data by about 0.088, 0.05, 0.1, and 0.056 A. The angles of N（3） O（3）-U, O（2）-N（1）-C（1）, N（3）-C（3）-N（4）, N（4）-C（3） C（4）, and C（4）-C（3）-N（3） are different from each other, which is due to existing interaction between oxygen in uranyl and hydrogen in amino group. This interaction is found to be intra-molecular hydrogen bond. Studies on the bond orders, Mulliken charges, and Mulliken populations demonstrate that uranyl oxo group functions as hydrogen-bond acceptors and H atoms in ligands act as hydrogen-bond donors forming hydrogen bonds within the complex.

Uranyl-HTTDN与R/S-丙硫磷农药的配位及选择性

为了探讨新型铀酰受体对丙硫磷的对映选择性,设计了一种新颖的配体:2-(2-羟基-3-甲氧基苯基)-9-(2-羟基苯基)硫代吡喃并[3,2-h]硫代色烯-4,7-二酮(HTTDN),并将HTTDN与铀酰离子结合,来构建一个新的Uranyl-HTTDN受体。在本工作中,利用密度泛函理论研究了Uranyl-HTTDN对R/S-丙硫磷农药的对映选择性识别。结果表明,在真空和甲苯中,Uranyl-HTTDN可以通过与丙硫磷中的S3原子配位来有效的识别R/S-丙硫磷,选择性系数均大于90%。

Plasma-facilitated modification of pumpkin vine-based biochar and its application for efficient elimination of uranyl from aqueous solution

An acrylic modified pumpkin vine-based biochar(p-PVB-PAA) is synthesized by non-thermal plasma-grafting modification of pumpkin vine-based biochar(PVB) for the removal of uranyl from an aqueous solution. Microscopic characterization reveals that compared to PVB the surface of p-PVBPAA has more oxygen-containing functional groups by strong chemical bonding and the specific surface area is increased to 275.3 m^2 g^-1 from 3.8 m^2g^-1. It is found that p-PVB-PAA showed a much higher maximum adsorption capacity for uranyl from aqueous solutions than PVB, which were207.02 mg g^-1 and 67.58 mg g^-1 at pH=5 and 298 K, respectively. Moreover, the adsorption behavior follows a pseudo-second-order kinetics model and the Langmuir adsorption model.Additionally, macroscopic experiments and spectroscopic studies verified that the significantly improved adsorption performance of the p-PVB-PAA is due to surface complexation and electrostatic interactions. Furthermore, the very high removal efficiency and excellent regeneration ability(the percentage of the removal still remained at nearly 90% after five cycles) makes this low-cost, easily obtained, and environmentally friendly material attractive for commercial application.

Influence of anions on the adsorption of uranyl on hydroxylated α-SiO_2(001):A first-principles study

The adsorption of uranyl on hydroxylated α-SiO_2(001) in the presence of a series of anionic ligands, i.e. OH^-, CO_3^(2-), NO_3^-, H_2PO_4^-, HPO_4^(2-),CH_3COO^-(Ac^-), C_6H_5COO^-(PhCO_2^-), C_6H_5O^-(PhO^-), was studied by the periodic density functional theory(DFT) implemented in the Vienna ab initio simulation package(VASP). For the ligands other than OH^-and PhO^-, only the bidentate coordination modes to the uranyl were considered. The excess charge effect of a charged system was first evaluated by constructing models with net charge as is or neutralized by creating defect at the bottom of silica, and the results show that a neutralized model, even with defects, is more realistic than the charged ones.All uranyl species prefer to bind with the deprotonated site(—O^-) rather than the protonated one(—O_H), which suggests that the increase of pH,which leads to the deprotonation of the surface, may enhance the uranyl adsorption. On the other hand, the anionic ligands, which are formed at higher pH, have negative effects. The weaker acidic ligands, such as H_2CO_3, H_3PO_4 and H_2O, whose speciation in solutions is sensitive to the fluctuation of pH, have more complex effect on the uranyl adsorption than strong acids or bases. Humic substances may coordinate with uranyl through carboxyl and phenolic groups, with the carboxyl group bound stronger. The ternary complexes with one bidentate(or monodentate)anion and one(or two) H20 as ligands, which leads to the uranyl penta-coordinated in its equatorial plane, are more favorable than other configurations when bound to the same anionic ligand. Both the charged nature and the coordination behavior of an anionic ligand are relevant to its ability to influence the adsorption of uranyl on the mineral surface. In addition, the uranyl species adsorbed at the surface functionalized by anionic ligands were also addressed, and the functionalized surfaces have weaker interaction with hydrated uranyl dication.

Synthesis and Structure of a New Dinuclear Uranyl Complex

With a heptadentate compartmental Schiff-base ligand H3L (1, 3-di[o-(salicylimino) ph- enoxyl]-2-propanol), a new binuclear diuranyl complex [(UO2)2L(OH)]?DMF, C38H45N5O13U2, was synthesized and the crystal structure was determined by X-ray diffraction techniques. The coordination geometry are two pentagonal bipyramids. In each pentagon four kinds of U-O (phenoxido, hydroxo, alkoxo and ether oxo) bonds are discussed.

Hydrothermal Synthesis,Crystal Structure and Luminescent Properties of an Organically Templated 2-D Uranyl Sulfate

An organically templated 2-D uranyl sulfate, {（C2H8N）[（UO2）Cl（SO4）（H2O）] }n 1, has been hydrothermally synthesized. The crystal and molecular structures have been determined by X-ray crystallography method and spectral techniques. 1 belongs to monoclinic, space group P21/c with a = 8.3545（17）, b = 10.550（2）, c = 12.370（3）A, β = 102.64（3）°, V = 1063.9（4）A3, Mr = 464.64, De= 2.901 g/cm^3, F（000） = 836,μ = 15.710 mm^-1, Z= 4, the final R = 0.0286 and wR = 0.0685 for 10164 observed reflections with Ⅰ 〉 2σ（Ⅰ）. 1 presents a two-dimensional layer-like structure constructed from infinite anionic [（UO2）Cl（H2O）（SO4）]^- layers with [C2H8N]^＋ cations balancing the charge and a number of intermoleeular hydrogen bonds （C-H…O and O-H…Cl） existing in the solid state. The fluorescence properties of 1 have also been discussed.

Synthesis and Crystal Structure of Bis(nitrate)bis(dipiperidin-1-yl-methanone)uranyl(II)

The new uranyl complex UO2(NO3)2[C5H10NC(O)NH10C5]2 has been synthesized and its structure was determined by single-crystal X-ray diffraction. Crystal data: C22H40N6O10U, monoclinic, space group P21/c, a = 11.151(3), b = 13.907(3), c = 10.067(2) ?, β = 115.602(4)°, V = 1408.0(5) ?3, Mr = 786.63, Z = 2, Dc = 1.855 g/cm3, F(000) = 772, μ = 5.827 mm-1, R = 0.0465 and wR = 0.1065 for 2916 observed reflections (I > 2σ(I)). The central uranyl ion is coordinated by six oxygen atoms, of which two are from the carbonyl groups of di-piperidin-1-yl-methanone molecules and the other four from two nitrate groups.

pH-dependent Synthesis of Octa-nuclear Uranyl-oxalate Network Mediated by U-shaped Linkers

In this work,we report a novel octa-nuclear uranyl(U8)motif[(UO2)8O4(μ3-OH)2(μ2-OH)2]4+embedded in a uranyl-oxalate coordination polymer(compound 1)based on a U-shaped linker with extra-long xylylene chains for stabilizing the resulting high-nuclear motif through additional cross-linking connectivity.A comparison with dimeric and monomeric uranyl compounds obtained at different pH value from the same hydrothermal system reveals that,solution pH plays a vital role in formation of this octa-nuclear uranyl motif by promoting hydrolysis of uranyl source.Since high similarity of eight uranium centers in this nearly planar U8 motif here,overlapping and broadening of signals in fluorescence,infra-red(IR)and Raman spectra can be found.

CRYSTAL STRUCTURE OF DI - NITRATOBIS(ETHYLCAPROLACTAM)URANYL(Ⅱ) UO_2[CH_2(CH_2)_4CONC_2H_5]_2(NO_3)_2

The crystal structure of Di-nitratobis(ethylcaprolactam)uranyl(Ⅱ) UO_2[CH_2(CH_2)_4CONC_2H_5]_2(NO_3)_2 was established by a single-crystal X-ray diffraction study.It is triclinie, space group P1, with a=7.171(2), b=8.655(3), c=10.182(5)A, α=78.27(3), β=70.63(3), γ=81.76(3)°, V=581.7(4)A^3, Z=l, Dc=1.94 g.cm^(-3).Final R value is 0.0218.The result reveals that uranyl ion is coordinated to six oxygen atoms, two of them are from two carbonyl groups of ethylcaprolactam and the other four are from two nitrate groups.

A<i>β</i>-Like Peptide Displayed on Bacteriophage T7 Catalyzes Chromate and Uranyl Reduction

In order to discover genes capable of catalyzing the reductive immobilization of toxic chromate and uranyl ions, we have created a T7 bacteriophage library containing cDNA from environmental microbes (i.e., Geobacter sulfurreducens and Shewanella oneidensis MR-1) that are known to mediate the reduction of chromate and uranyl ions. After three rounds of screening, ten bacteriophage mutants were found to mediate the NADH-dependent reduction of chromate and uranyl ions whose cDNA encodes polypeptide chains ranging 14 to 73 amino acids in length. All identified sequences contain disordered structural motifs similar to the β-amyloid peptide (Aβ) known to promote aggregation and formation of high-affinity metal binding sites. Confirmation of this structural similarity involved phage display of the 42 amino-acid Aβ-peptides that have been found to catalyze the NADH-dependent reduction of both chromate and uranyl ions. Transmission electron microscopy (TEM) and X-ray absorption near edge structure (XANES) measurements confirm that reduced uranium is present on the surface of bacteriophage expressing the Aβ-peptide. The surface-displayed Aβ-like peptide on bacteriophage has the potential to couple naturally occurring electron transfer shuttles present in soils to promote economically viable remediation of contaminated sites containing toxic chromate and uranyl ions.

Adsorption of uranyl complex ions on hydrous titanium oxide (HTO)——Ⅱ Infrared spectrum investigation

-The i. r. spectra of Na4 [UO2 (CO3)3], Na [UO2 (OH)3] and the surface species of uranium on HTO underthe condition of flowing natural seawater and concentrated seawater (NaCl-NaHCO3-U) were recorded, with the bands of urany! of surface species obtained and the finding that iigands of surface species besides HTO are mainly water and OH, and there are some CO32- groups under the condition of natural seawater. Some relations between the complex properties and the j. r. spectroscopic characters for uranyl complexes were studied, and the transferred change quantity of surface complex was calculated.Structure models for surface species of adsorption are herein presented and the mechanism for uranium adsorption is deduced.

基于Uranyl-Salophen-SDS体系荧光光谱法检测铀

铀是一种重要的自然资源,在多个领域都有广泛的用途,所以检测铀也变得越来越有意义。建立了一种操作简单,价格低廉,灵敏度高的检测方法,首先将Salophen与铀酰结合成Uranyl-Salophen配合物,接着采用十二烷基硫酸钠(SDS)表面活性剂将配合物包裹,从而达到增敏检测U(VI)的目的。优化了时间、温度、SDS剂量、pH条件,在最优条件下荧光强度与铀的浓度范围在0.005~3.5 mol/m L下呈现良好的线性关系,在实际样品中检测铀的回收率在96%~103%。

Adsorption behavior of uranyl ions onto amino-type adsorbents prepared by radiation-induced graft copolymerization

Amino-type adsorbents(ATAs) were prepared by radiation-induced graft copolymerization of 4-hydroxybutyl acry late glycidyl ether(HB) onto a polyethylene-coated polypropylene(PE/PP) duplex fiber of a non-woven fabric,and modified with different amines of ethylenediamine(EDA),diethylenetriamine(DETA),triethylenetetramine(TETA) and diethylamine(DEA).The adsorption behavior of uranyl ions onto the ATAs was studied in batch experiments.The effects of the contact time,initial concentration of the ions,temperature,and pH value.The salinity were investigated along with the adsorption kinetics and the adsorption isotherms.The kinetic experimental data followed the pseudo second-order kinetic model,and the adsorption isotherms correlated well with the Langmuir model.The ATAs showed good efficiency in adsorbing uranyl ions,with the best saturation adsorption capacity being 64.26 mg g^(-1) for ATA-DETA within 120 min.The temperature dependence of ATADETA was quite abnormal and the quickest behavior was obtained at 25 ℃.ATAs showed good adsorption capacity over a wide pH range of 4.0-8.5,and HCl could be used in the elution process.Salinity of the solution had great effect on the adsorption capacity,3.5%salinity resulted in a 55%loss of capacity from ATA-DETA.The selectivity of ATA-DETA showed an order of:UO_2^(2+)≈Fe^(3+)> Zn^(2+) > VO_3^- > Co^(2+) > Ni^(2+).

A molecular dynamics study of uranyl-carbonate complexes adsorbed on basal surfaces of clay minerals

We use molecular dynamics simulation to study the mechanisms involved in the adsorption of aqueous uranyl species(UO_2^(2+)) to the basal surfaces of clay minerals,including kaolinite,pyrophyllite and montmorillonite.Uranyl ion can form various complexes with carbonates,namely,[UO_2(H_2O)_5]^(2+),[UO_2(H_2O)3(CO_3)],[UO_2(H_2O)2(CO_3)_2]^(2-),[UO_2(CO_3)_3]^(4-).The simulations show that at aqueous clay interfaces,both uranyl species and surface type control the adsorption pattern.The noncarbonato and monocarbonato uranyl species can form outer-sphere complexes on siloxane surfaces through electrostatic interaction,but the dicarbonato and tricarbonato uranyl complexes rarely adsorb on the siloxane surfaces.Strong outer-sphere adsorptions of the uranylcarbonate complexes on gibbsite surfaces are observed,which are fixed by hydrogen bonds between the ligands(carbonate and/or H_2O) and surface hydroxyls.The sorption behaviors derived in this study provide new insights into understanding the migration and enrichment of uranium and other radionuclides.

Synthesis and Crystal Structure of Bis(nitrate)- bis(N,N'-dimethyl-N,N'-dibenzenyl-urea)uranyl(Ⅱ)

The new uranyl complex UO2(NO3)2[PhN(CH3)C(O)(CH3)NPh]2 was synthesized and its crystal structure has been determined by single-crystal X-ray diffraction. Crystal data: C30H32N6O10U, triclinic, space group P with a = 7.772(1), b = 9.267(1), c = 12.644(1) ? a = 68.246(8), b = 73.871(9), g = 84.99(1)o, V = 812.4(2) ?, Mr = 874.65, Z = 1, Dc = 1.788 g/cm3, F(000) = 426, m = 5.062 mm-1, the final R = 0.022 and wR = 0.059 for 3571 observed reflections (I > 2s(I)). The central uranyl ion is coordinated by six oxygen atoms, two from the carbonyl groups of N,N-dimethyl-N,N-dibenzenyl-urea molecules and the other four from two nitrate groups.

Effects of a low-radiotoxicity uranium salt(uranyl acetate) on biochemical and hematological parameters of the catfish,Clarias gariepinus

Specimens of Clarias gariepinus were treated with lethal(70,75,80,85,90,and 95 mg/L) and sub-lethal concentrations(8,12 and 16 mg/L) of uranyl acetate,a low-radiotoxicity uranium salt. The LC 50 value was registered as 81.45 mg/L. The protein and glycogen concentrations in liver and muscles were decreased in the fish exposed to sub-lethal concentrations. The red blood cell(RBC) and white blood cell(WBC) counts,haemoglobin(Hb) concentration and haematocrit(Hct) values were decreased. Different blood indices like mean corpuscular volume(MCV),mean corpuscular haemoglobin(MCH) and mean corpuscular haemoglobin concentration(MCHC) were negatively affected. Level of plasma glucose was elevated whereas protein was decreased. The level of calcium concentration(Ca) was declined in the blood of exposed fish whereas magnesium(Mg) remains unchanged. The activity level of glutamic-oxaloacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) was elevated in exposed fish. These effects were more pronounced in the last period of exposure and in higher concentrations. Results of the present study indicate that uranyl acetate has adverse effects on C larias gariepinus and causes changes in the biochemical and hematological parameters of the fish.

Synthesis and Crystal Structure of Bis(nitrate)bis(N-n-octyl-α-pyrrolidone)uranyl (II)

The crystal structure of the title compound UO2(NO3)2[CH2(CH2)2CONC8H17] was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P , a = 7.456(2), b = 8.371(2), c = 13.470(3) ? ?= 95.66(1), ?= 94.64(2), ?= 102.67(2), C24H46N4O10U, Mr = 788.68, V = 811.7(3) ?, Dc = 1.613 g/cm3, Z = 1, F(000) = 390, ?= 5.052 mm-1, the final R = 0.0256 and wR = 0.0568 for 2826 observed reflections (I > 2(I)). The central uranyl ions are coordinated by six oxygen atoms. Two of them are from the carbonyl groups of N-octyl-a-pyrrolidone molecules, and the other four from two nitrate groups.

Extraction of uranyl(VI) ion with N,N-dibutyloctadecanamide from nitric acid solution

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Synthesis,structures and photoluminescence of uranyl polyoxometalate clusters based on trilacunary[TeW_(9)O_(33)]^(8-)

Synthesis of uranyl polyoxometalate clusters attract more attention but remain great challenging.Herein,two uranyl polyoxometalate inorganic clusters of{Na_(6)(NH_(4))_(19)[(TeW_(9)O_(33))_(4)[TeO_(2)(OH)](UO_(2))4(H_(2)O)_(2)]·50H_(2)O}n(1,Te-U_(4))and(NH_(4))18{Na@[(TeW_(9)O_(32)OH)(TeW_(9)O_(33))_(2)[TeO(OH)][W_(3)O_(12)(μ_(3)-OH)](UO_(2))_(6)(μ_(2)-OH)_(2)H_(2)O]}·75H_(2)O(2,Te-U6)were prepared using trilacunary[α-B-TeW_(9)O_(33)]8-as inorganic ligands.Structural analysis showed that compound 1 is a one-dimensional chain structure formed by tetrameric aggregates of[(α-B-TeW_(9)O_(33))_(4)(TeO_(2)(OH))(UO_(2))_(4)(H_(2)O)2]25-as nodes and Na+ions as linkers.The anionic tetrameric aggregates in 1 is made of two sandwich-type dimers of[(TeW_(9)O_(33))_(2)(UO_(2))_(2)H_(2)O]12-bridged by a[TeO_(2)(OH)]-unit.Compound 2 is a triangular trimeric architecture templated by Na+ion.The solid-state luminescence emission spectra of compounds 1 and 2 show the characteristic peaks of uranyl ions.Compound 1 with one-dimensional chain structure exhibited a higher photoluminescence quantum yields(PLQY)than that of 2,due to the more rigidity of 1 reducing the nonradiative transitions.