Probing Diverse Disulfur Ligands in the Mo_2S_n~(–/0)(n = 4 ～ 8) Clusters: Structural Evolution and Chemical Bonding

Density functional theory(DFT) and coupled cluster theory(CCSD(T)) calculations were employed to investigate the geometric and electronic structures of a range of dinuclear molybdenum sulfide clusters, Mo_2S_n~– and Mo_2S_n(n = 4～8). The results showed that the sulfur atoms tended to occupy the terminal sites of the clusters continuously in the process of sequential sulfidation. After the oxidation state of Mo atoms reached the maximum of +6, diverse disulfur ligands emerged in the sulfur-rich Mo_2S_n~(–/0)(n = 7, 8) clusters. The driving forces of removing a sulfur atom from different S ligands in Mo_2S_n~(–/0)(n = 4～8) clusters, especially from those disulfur units, were evaluated. The corresponding order may provide insight into the pretreatment of fresh MoS_2 catalysts. Vertical detachment energies(VDEs) were predicted according to the Generalized Koopmans' theorem, and then the photoelectron spectra(PES) were simulated. Molecular orbital and spin density values were analyzed to elucidate the chemical bonding and the evolutionary behavior in the dinuclear molybdenum sulfide clusters.     

Interactions with ATP, DNA Cleavage and Anti-tumor Activities of Complexes with Anions [Mo（V）O2（O2CeH4）2]^3-, [Mo（Ⅴ）0.5W（Ⅵ）0.5O2（O2C6H4）2]^2.5- and [W（Ⅵ）O2（O2C6H4）2]^2-

(NH3CH2CH2NH2)3[Mo(Ⅴ)O2(O2C6H4)2] (1), (NH3CH2CH2NH2)2.5[Mo(Ⅴ)o.sW(Ⅵ)o.502(O2C6H4)2] (2) and(NH3CH2CH2NH2)2[VC(Ⅵ)O2(O2C6H4)2] (3) were synthesized, structurally characterized by X-ray diffraction analysis, and studied on their interactions with ATP, their DNA cleavage activities and antitumor properties. The redox state of molybdenum was not changed on going from crystal to aqueous solutions in complexes 1 and 2, while tungsten underwent reduction from W(VI) to W(V) in complexes 2 and 3. ATP promoted the oxidation of both molybdenum and tungsten from M(Ⅴ) to M(Ⅵ) and the hydrolysis of catecholate ligands in solution consisting of ATP and the complexes. Complex 1 possesses fairly good activity to DNA cleavage and against tumor S180 in mice, and is more effective than the control drug cyclophosphamide under the identical conditions. However, complexes 2 and 3 exhibited marginal effectiveness. The effectiveness of anti-tumor of the complexes was related positively to their DNA cleavage activities and their hydrolysis of catecholate ligands.     

STUDY ON TRANSPORT AND SEPARATION OF MO(Ⅵ) ION BY USING ELM OF TOA-SPAN 80-OXYLENE

A new ELM was prepared for the study on transport of Mo(Ⅵ) ion. Under the experimental conditions, Mo(Ⅵ) can be transported completely and separated from the co-lons.The emulsion liquid membrane(ELM) with Tri-n-octylamine(TOA) as a carrier used for the transport of Mo(Ⅵ) ions and its separation from some cations have been reported in this paper. The transport percentage of Mo(Ⅵ) ion through ELM in 5 min corresponds to that of the literature in 165 min.     

Adsorption behavior of uranium on polyvinyl alcohol-g-amidoxime: Physicochemical properties, kinetic and thermodynamic aspects

Amidoxime-based adsorbents are widely studied as the main adsorbent in the recovery of uranium from seawater.However,the adsorption rate and loading capacity of such adsorbents should be further improved due to the economic viability consideration.In this paper,polyvinyl alcohol functionalized with amidoxime(PVA-g-AO)has been prepared as a new adsorbent for uranium(Ⅵ)adsorption from aqueous solution.The physicochemical properties of PVA-g-AO were investigated using infrared spectroscopy(IR),scanning electron microscope(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).Results showed that the ligand monomers were successfully grafted onto the matrixes.The XRD and XPS analysis showed that uranium was adsorbed in metal ionic form rather than in crystal form.Uranyl(U(Ⅵ))adsorption properties onto PVA-g-AO were evaluated.The adsorption of U(Ⅵ)by PVA-g-AO was fast,with an equilibrium time of less than 50 min.Additionally the maximum adsorption capacity reached 42.84 mg/g at pH 4.0.     

Chromatographic separation of cerium(Ⅲ) in L-valine medium using poly[dibenzo-18-crown-6]

A column chromatographic method has been developed for the separation and determination of cerium(Ⅲ) using poly[dibenzo-18-crown-6]. The separation was carried out in L-valine medium. The adsorption of cerium(Ⅲ) was quantitative from 1×10-1 to 1×10-4 mol/L L-valine. Amongst the various eluents, 1.0-8.0 mol/L hydrochloric acid, 1.0-8.0 mol/L hydrobromic acid, 1.0-8.0 mol/L perchloric acid, 1.0-2.0 mol/L sulfuric acid and 4.0-5.0 mol/L acetic acid, were found to be the efficient eluents for cerium(Ⅲ). The capacity of poly[dibenzo-18-crown-6] for cerium(Ⅲ) was (0.428±0.01) mmol/g. The method was applied to the separation of cerium(Ⅲ) from associated elements link uranium(Ⅵ) and thorium(Ⅳ). It was also applied for the determination of cerium(Ⅲ) in geological samples. The method is simple, rapid and selective with good reproducibility (approximately±2% ).     

In-situ reduction synthesis of manganese dioxide@polypyrrole core/shell nanomaterial for highly efficient enrichment of U(Ⅵ) and Eu(Ⅲ)

Radionuclides with long half-life are toxic,and thereby result in serious threat to human beings and ecological balance.Herein,a simple two-step synthesis method was used to prepare manganese dioxide@polypyrrole(Mn O_2@PPy)core/shell structures for efficient removal of U(Ⅵ)and Eu(Ⅲ)from aqueous solutions.The adsorption of U(Ⅵ)and Eu(Ⅲ)were investigated under different kinds of experimental conditions.The experimental results suggested that the adsorption of U(Ⅵ)and Eu(Ⅲ)on Mn O_2@PPy were greatly affected by p H.U(Ⅵ)adsorption on Mn O_2@PPy was independent of ionic strength at p H6.0,and dependent on ionic strength at p H6.0.However,Eu(Ⅲ)adsorption on Mn O_2@PPy was independent of ionic strength at the whole p H range of experimental conditions.The maximum adsorption capacities(q_(max))of U(Ⅵ)and Eu(Ⅲ)were 63.04 and54.74 mg g~(-1)at T=298 K,respectively.The BET,XRD,FTIR and XPS analysis evidenced that high adsorption capacities of U(Ⅵ)and Eu(Ⅲ)on Mn O_2@PPy were mainly due to high surface area and rich metal oxygen-containing group(i.e.,Mn–OH and Mn–O),and the interaction was mainly attributed to strong surface complexation and electrostatic interaction.This study highlighted the excellent adsorption performance of U(Ⅵ)and Eu(Ⅲ)on Mn O_2@PPy and could provide the reference for the elimination of radionuclides in real wastewater management.     

Intermolecular Phenolic Hydroxy Methylation Occurring between Chiral N,N''''-Bis(2-hydroxyphenyl)-2,2-dimethyl-1,3-dioxolane-4,5-dicarbamide and Co-crystallized Methanol under Electron Impact Ionization Conditions

Introduction Chiral C2-symmetric bisamides are an important and useful type of ligands, which have been widely used in asymmetric catalysis.1-7 They were used successfully in asymmetric molybdenum (0)-catalyzed allylic substitu-tion,2-5 palladium-catalyzed alkylation,1,6 and Lewis acid-catalyzed asymmetric nucleophilic ring opening of epoxides,7 etc. In addition, bisamides are useful ligands for coordination chemistry8 and are used as building blocks9 for the synthesis of dissymmetrical tetra…     

THE SYNTHESIS AND CRYSTAL STRUCTURE OF A NOVEL MOLYBDENUM-SULFUR CLUSTER COMPLEX, (NH_4)_4[Mo_3(NO)_4S_(13)]·3H_2O

The title compound has been synthesized, the crystal structure of which has been detorminedby the single-crystal X-ray diffraction method. The crystal belongs to triclinic space group C-P1 with the unit cell parameters: a =9.535(2)A, b = 9.740(2)A, c = 15.795(4)A, α = 89.85(2)°, β = 91.80(2)°, γ = 99.37(1)°,ν = 1446.6A~3, Ζ = 2. The structure is refined to R = 0.075, R_w = 0.074 for 1903 reflections. There are diverse bonding modes of molybdenum and sulfur in this eompound. The twosulfur atoms at the center bond to three molybdenum atoms from respective sides and formthe two apices of a trigonal bipyramid. Besides, there are S_2~(-2) ligands and a polysulfur chaincomposed of three sulfur atoms. The coordination number for the three molybdenum atomsis seven. Their coordination polyhedra are somewhat distorted pentagonal bipyramid. Eachof the three NO ligands coordinated to molybdenum gives a linear group of Mo-N-O, whilethe fourth NO ligund bonded with a polysulfur chain forms a bent group of S-N     

Solvent Effects on Complexation of Molybdenum（Ⅵ） with Nitrilotriacetic Acid in Different Aqueous Solutions of Propanol

By using spectrophotometric and potentiometric techniques the formation constants of the species formed in the systems H^＋＋ Mo（Ⅵ）＋nitrilotriacetic acid and H^＋ ＋ nitrilotriacetic acid have been determined in aqueous solutions of propanol at 25 ℃ and constant ionic strength 0.1 molodm^-3 sodium perchlorate. The composition of the complex was determined by the continuous variation method. It was shown that molybdenum（Ⅵ） forms a mononuclear 1 ： 1 complex with nitrilotriacetic acid of the type MoO3L^-3 at -lg[H^＋] =5.8. The formation constants in various media were analyzed in terms of Kamlet and Taft＇s parameters. Linear relationships were observed when lg Ks was plotted versusp. Finally, the results were discussed in terms of the effect of solvent on complexation.     

Highly efficient removal of Cr(Ⅵ)from wastewater via adsorption with novel magnetic Fe_3O_4@C@MgAl-layered double-hydroxide

Novel magnetic Fe_3O_4@C@MgAl-layerecl double-hydroxide(LDH) nanoparticles have been successfully prepared by the chemical self-assembly methods.The properties of surface functional groups,crystal structure,magnetism and surface morphology of magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD),thermal gravity-differential thermal gravity(TG-DTG),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).The adsorption studies of the novel adsorbent in removing heavy metals Cr(Ⅵ) from waste water showed that the maximum absorption amount of Cr(Ⅵ) was 152.0 mg/g at 40℃ and pH 6.0.The excellent adsorption capacity of the Fe_3O_4@C@MgAl-LDH nano-absorbents plus their easy separation,environmentally friendly composition and reusability makes them more suitable adsorbents for the removal of metal ions from waste water.     

Preparation of Novel Ultrathin Co doped MoS2 Nanosheets Piezocatalyst for Fast Simultaneous Decomposition of Cr(Ⅵ) and MB in Dark

Ultrathin Co doped MoS2 nanosheets(NSs) with thickness of 3.2 nm was used to simultaneously decompose Cr(Ⅵ) and MB in dark through ultrasonic vibration-assisted piezocatalytic effect. The significantly enhanced piezocatalytic performance of Co doped MoS2 NSs was found in comparison to the pristine MoS2 NSs. The high piezocatalytic activity of Co doped MoS2 NSs may originate from the large amount of charge carriers due to Co doping. The efficient separation of electron-hole pairs under spontaneous polarization were also investigated ill detail, which is responsible for reduction of Cr(Ⅵ) and oxidation of methylene blue(MB). The active species trapping experiments demonstrate that e and ·O2^- are main active substances for Cr(Ⅵ) reduction, while h+,·OH, and ·O2^- participate in MB degradation.     

STUDY ON THE ANION-EXCHANGE BEHAVIOUR OF MOLYBDENUM(Ⅵ) AND TUNGSTEN(Ⅵ)IN MIXED ORGANIC-AQUEOUS SOLVENTS

The anion一exehange behaviour0fFF)molybdenum(Vl)and tungsten(VlOna stroog一baseanion一exehange re吕in(Zerolithas been studied in hydroehlorie aeid and eom-Plexing agent一hydrochlorie aeid sy‘tems eontaining an organie solvent.The mainf己etors affeeting the distribution of molybdenum(Vl》and tungsten(vl)betweenresin and昌olution oh乙se昌工n an organie solvent and the distribution meehan工sm aredi‘c二usseel.The Poss一七〕王l工ty主5 offered for the seParation and eoneentration of traeeamoun…     

在L-缬氨酸介质中应用聚二苯并-18-冠醚-6-分离铈（III)

 A column chromatographic method has been developed for the separation and determination of cerium(Ⅲ) using poly［dibenzo-18-crown-6］. The separation was carried out in L-valine medium. The adsorption of cerium(Ⅲ) was quantitative from 1×10-1 to 1×10-4 mol/L L-valine. Amongst the various eluents, 1.0-8.0 mol/L hydrochloric acid, 1.0-8.0 mol/L hydrobromic acid, 1.0-8.0 mol/L perchloric acid, 1.0-2.0 mol/L sulfuric acid and 4.0-5.0 mol/L acetic acid, were found to be the efficient eluents for cerium(Ⅲ). The capacity of poly［dibenzo-18-crown-6］ for cerium(Ⅲ) was （0.428±0.01） mmol/g. The method was applied to the separation of cerium(Ⅲ) from associated elements link uranium(Ⅵ) and thorium(Ⅳ). It was also applied for the determination of cerium(Ⅲ) in geological samples. The method is simple, rapid and selective with good reproducibility (approximately±2%).     

BORONIC ACIDS AS LIGANDS FOR AFFINITY CHROMATOGRAPHY

 A review on the principles and applications of boronic acids as affinity ligands for the chromatographic separation of carbohydrates, nucleic acid components, glycoproteins, and other small biomolecules. The mechanisms of interactions between boronate ligands and analytes are described. Various boronate ligands and supports are discussed. Examples of the use of boronate affinity chromatography for separation of each class of analytes are presented.     

CRYSTAL STRUCTURE OF TRINUCLEAR MOLYBDENUM CLUSTER H(Mo_3O(OAc)_3Cl_6)·3H_2O

<正> INTRODUCTION. Reacting of MoCl_3·3H_2O with organic ligands to-synthesize di- and trinuclear molybdenum complexes is an interesting research area. We wish to report the crystal structure of the title compound. It is one of our research results on structural chemistry of di- and trinuclear molybdenum complexes. The title compound was synthesized by reacting of MoCl_3·3H_2O with CH_3COCl。     

Preconcentration by Using Microcrystalline Phenolphthalein for Determining Trace Molybdenum （Ⅵ） in Water by GFAAS

Molybdenum（ Ⅵ ） is a biologically essential trace element and its role in an extremely wide variety of systems has been reported. Most common methods often fail to determine trace Mo （ Ⅵ ） in the analysis of molybdenum-containing samples, due to limitations such as inadequate detection limits and matrix interference, which make the direct determinations impossible. To solve this problem, various approaches are employed to concentrate and separate Mo（ Ⅵ ） to detectable levels. Concentration and separation methods play a main role in the analysis of trace Mo（Ⅵ）. Therefore, many separation and preconcentration procedures have been developed for the determination of Mo （ Ⅵ ）.     

Electrogeneration of ferrate (Ⅵ) in low concentration NaOH solution for flow-injection-chemiluminescence detection

<正>The possibility of direct analytical applications of ferrate(Ⅵ) solution,which was freshly electrogenerated in low-concentration NaOH electrolyte,was studied by a flow-injection-chemiluminescence(FI-CL) system.It was found that some inorganic ions, organic molecule and biomolecule could enhance the chemiluminescence emission caused by ferrate(Ⅵ)-luminol reaction.V(Ⅴ), Ca(Ⅱ),Mg(Ⅱ),phloroglucinol,and bovine hemoglobin(Hb) chosen as samples were successfully detected by this developed method.The analytical characteristics of the system for the analytes determination including linear ranges,correlation coefficients, limits of detection combined with FI analysis were studied.     

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

1 INTRODUCTION Tri-butyl phosphate (TBP) has been widely used as the extraction reagent in U-Th fuel to separate uranium from thorium. But di-butyl phos- phate (DBP) and butyl phosphate (MBP), the radio- lytic products of TBP, exhibit some coordinated ability to the fission elements, such as Zr and Nb. The substitutes for TBP have being studied for several decades[1～4]. The physical and chemical properties of amides are similar to those of TBP and they selectively extract U(Ⅵ…     

Design criteria for tetradentate phenanthroline-derived heterocyclic ligands to separate Am(Ⅲ) from Eu(Ⅲ)

To design novel phenanthroline-derived soft ligands for selectively separating minor actinides from lanthanides, four tetradentate phenanthroline-derived heterocyclic ligands(BTPhen, BPyPhen, BPzPhen, and BBizPhen) were constructed and their complexation behaviors with Am(ⅡI) and Eu(ⅡI) were systematically investigated by density functional theory(DFT) coupled with relativistic small-core pseudopotential. In all the 1:1-type species, the metal ion is in the center of the cavity and coordinates with two nitrogen atoms(N1 and N1′) of the phenanthroline skeleton and the other two nitrogen atoms(N2 and N2′) of the auxiliary groups. The bond lengths of Am–N are comparable to or even shorter than those of Eu–N bonds because the ionic radii of Am(ⅡI) are larger than those of Eu(ⅡI). Additionally, the negative ΔΔGAm/Eu value for the reaction of [M(H2O)4-(NO3)3] + L → ML(NO3)3 + 4H2 O indicates that the complexation reaction of Am(ⅡI) is more energetically favorable than that of Eu(ⅡI); this can be considered as an important design criterion to screen phenanthroline-derived ligands for MA(ⅡI) extraction. According to this criterion, the selectivity of tetradentate phenanthroline-derived ligands for separating Am(ⅡI) over Eu(ⅡI) follows the order of BTPhen BBizPhen BPyPhen BPzPhen.     

配合物(ArO)2Yb(NPh2)2K(THF)4(Ar=C6H2-t-Bu3-2,4,6)的合成、分子结构和催化行为

Reaction of anhydrous YbC13 with 2 equiv, of sodium 2,4,6-tri-tert-butylphenoxide (ArONa, Ar=C6H2-t-Bu3-2,4,6) and 2 equiv, of potassium diphenyl amide in THF afforded the first bis(aryloxo) amido-lanthanide complex of (ArO)2Yb(NPh2)2K(THF)4 (1). In 1, the ytterbium and potassium were bridged via diphenyl amido ligands.The ytterbium metal center was coordinated to two oxygen atoms of aryloxide ligands and two nitrogen atoms of diphenyl amido ligands in a conventional distorted tetrahedral fashion, while the potassium interacted in η^2-fashion with two phenyl rings of the diphenyl amido ligands besides four THF molecules. 1 displayed moderate catalytic activities for the polymerization of methyl methacrylate and acrylonitrile.