Synthesis of a new salt containing polyoxometallate anion and M-Cu-S cluster cation [MS_4Cu_4(γ-MePy)_8][M_6O_19] (M = Mo,W).Crystal structure of [WS_4Cu_4(γ-MePy)_8][W_6O_19]

Reactions of (NH4)2MS4, AgBr and CuBr in r-methylpyridine produced one new compound, [MS4Cu4(r-MePy)8]M6O19] (1, M = W; 2, M = Mo), of which 1 was characterized by single crystal X-ray analysis. The crystal data: orthorhombic, Pbcn, a = 15.434(4),b= 16.732(2), c = 28.657(7) A, V = 7400.8(8) A3, Z = 4, R = 0.072 for 3121 independent data. The compound is the first example which contains both polyoxotnngstate anion and heteropolynuclear cluster cation. In the structure of the cation four edges of the tetrahedral WS42- core are coordinated by four copper atoms, giving a WS4Cu4 aggregate of approximate D2h symmetry. The differences between the reaction of Cu+ with MS42- and that of Ag+ with MS42- in pyridine and its derivatives are discussed.

Heterostructured Pt-Ni_(3)Mo_(3)N formed via ammonia-containing polyoxometalates for highly efficient electrocatalytic hydrogen evolution in acid medium

Constructing heterostructured nanohybrid is considered as a prominent route to fabricate alternative electrocatalysts to commercial Pt/C for hydrogen evolution reaction(HER).In this work,(NH_(4))_(4)[NiH_(6)Mo_(6)O_(4)]·5H_(2)O polyoxometalates(NiMo_(6))are adopted as the cluster precursors for simple fabrication of heterostructured Pt-Ni_(3)Mo_(3)N nanohybrids supported by carbon black(Pt-Ni_(3)Mo_(3)N/C)without using additional N sources.The improved porosity and enhanced electronic interaction of Pt-Ni_(3)Mo_(3)N/C should be attributed to the integration of Pt with NiMo_(6),which favors the mass transport,promotes the formation of exposed catalytic sites,and benefits the regulation of intrinsic activity.Thus,the as-obtained Pt-Ni_(3)Mo_(3)N/C exhibits impressive and durable HER performance as indicated by the low overpotential of 13.7 mV at the current density of 10 mA cm^(-2) and the stable overpotential during continuous working at 100 mA cm^(-2) for 100 h.This work provides significant insights for the synthesis of new highly active heterostructured electrocatalysts for renewable energy devices.

Recent Advances on Polyoxometalate-Based Ion-Conducting Electrolytes for Energy-Related Devices

Solid-state electrolytes have attracted considerable attention in new energyrelated devices due to their high safety and broad application platform.Polyoxometalates(POMs)are a kind of molecular-level cluster compounds with unique structures.In recent years,owing to their abundant physicochemical properties(including high ionic conductivity and reversible redox activity),POMs have shown great potential in becoming a new generation of solid-state electrolytes.In this review,an overview is investigated about how POMs have evolved as ion-conducting materials from basic research to novel solid-state electrolytes in energy devices.First,some expressive POM-based ion-conducting materials in recent years are introduced and classified,mainly inspecting their structural and functional relationship.After that,it is further focused on the application of these ionconducting electrolytes in the fields of proton exchange membranes,supercapacitors,and ion batteries.In addition,some properties of POMs(such as inherent dimension,capable of forming stable hydrogen bonds,and reversible bonding to water molecules)enable these functional POM-based electrolytes to be employed in innovative applications such as ion selection,humidity sensing,and smart materials.Finally,some fundamental recommendations are given on the current opportunities and challenges of POM-based ion-conducting electrolytes.

Single-Molecule Confinement Induced Intrinsic Multi-Electron Redox-Activity to Enhance Supercapacitor Performance

Aggregation of polyoxometalates(POM)is largely responsible for the reduced performance of POM-based energy-storage systems.To address this challenge,here,the precise confinement of single Keggin-type POM molecule in a porous carbon(PC)of unimodal super-micropore(micro-PC)is realized.Such precise single-molecule confinement enables sufficient activity center exposure and maximum electron-transfer from micro-PC to POM,which well stabilizes the electron-accepting molecules and thoroughly activates its inherent multi-electron redox-activity.In particular,the redox-activities and electron-accepting properties of the confined POM molecule are revealed to be super-micropore pore size-dependent by experiment and spectroscopy as well as theoretical calculation.Meanwhile,the molecularly dispersed POM molecules confined steadily in the“cage”of micro-PC exhibit unprecedented large-negative-potential stability and multiple-peak redox-activity at an ultra-low loading of~11.4 wt%.As a result,the fabricated solid-state supercapacitor achieves a remarkable areal capacitance,ultrahigh energy and power density of 443 mF cm^(-2),0.12 mWh cm^(-2)and 21.1 mW cm^(-2),respectively.This work establishes a novel strategy for the precise confinement of single POM molecule,providing a versatile approach to inducing the intrinsic activity of POMs for advanced energy-storage systems.

Amorphous TiO_2-supported Keggin-type ionic liquid catalyst catalytic oxidation of dibenzothiophene in diesel

Supported ionic liquid(IL) catalysts [Cmim]PMoO/Am TiO(amorphous TiO) were synthesized through a one-step method for extraction coupled catalytic oxidative desulfurization(ECODS) system. Characterizations such as FTIR, DRS,wide-angle XRD, Nadsorption–desorption and XPS were applied to analyze the morphology and Keggin structure of the catalysts. In ECODS with hydrogen peroxide as the oxidant, it was found that ILs with longer alkyl chains in the cationic moiety had a better effect on the removal of dibenzothiophene. The desulfurization could reach 100% under optimal conditions, and GC–MS analysis was employed to detect the oxidized product after the reaction. Factors affecting the desulfurization efficiencies were discussed, and a possible mechanism was proposed. In addition, cyclic experiments were also conducted to investigate the recyclability of the supported catalyst. The catalytic activity of [Cmim]PMoO/Am TiOonly dropped from 100% to 92.9% after ten cycles, demonstrating the good recycling performance of the catalyst and its potential industrial application.

Supramolecular Structural Inorganic-organic Hybrid[(4-Bromoanilimiun)([18]crown-6)]3[PMo(12)O(40)]·CH3CN

A novel supramolecular structural inorganic-organic hybrid [（4-bromoanilimiun）（[18]crown-6）]3[PMo（12）O40]·CH3 CN has been synthesized through standard solvent evaporated method. The structure of the title compound was determined through single-crystal X-ray diffraction analysis. It crystallizes in monoclinic system with P21/n space group. The crystal data are a = 18.9529（4）, b = 26.4444（5）, c = 19.0985（4） A, β = 90.132（6）o, V = 9572.1（3） A^3, Z = 4, Dc= 2.203 g·cm^（–1）, μ = 14.956 mm^（–1）, F（000） = 6192, S = 1.098, the final R = 0.0859 and w R（I 〉 2σ（I）） = 0.2100. Supramolecular cations are constructed through strong N–H…O hydrogen bonding interaction between the six oxygen atoms of [18]crown-6 molecule and nitrogen atom of（4-bromoanilimiun） cation. Three kinds of different arranged supramolecular cations exist in the title compound, which are filled into the large space formed by [PMo（12）O40] polyoxoanions. Thermogravimentic differential thermal analysis revealed that hydrogen bonding interaction and intermolecular interaction play an important role in maintaining the stability of the title compound.

Synthesis, Characterization and Conductivity of α-Keggin-type Nanoparticles, Co(en)_3PMo_(12)O_(40)·8H_2O with Optical Activity

Polyoxometallates Co(en) 3PMo 12O 40·8H 2O(+,-)[abbreviated as PMo 12-Co(+,-)], nanoparticles were synthesized by the chemical precipitation reaction at room temperature for the first time. They were characterized by means of elemental analyses, IR spectrometry and X-ray diffraction. The images of scanning electron microscopy(SEM) and the results of calculation by using the Scherrer equation for the line widths of the XRD patterns were used to estimate the average particle size of the powder products, which was 40 nm. The results show that the nanoparticle size was affected by starting materials′ concentrations. The particles had a small size and a narrow distribution, when the concentrations of H 3PMo 12O 40·24H 2O and Co(en) 3I 3·H 2O were around 1.7×10 -4 and 1.0×10 -3 mol/L, respectively. When the concentration was increased, there was no significant increase in the particle size, but more polydisperse Co(en) 3(PMo 12O 40) (+, -) were obtained. In poly(ethylene glycol)(PEG) with an average molecular weight(M W) of 600 g/mol and containing LiClO 4[n(O)/n(Li)=100∶1] as the supporting electrolyte, the conductivity of the composite system increases upon the addition of PMo 12-Co(+ or -) nanoparticles, which was measured by the a.c. impedance technique. The interactions among PEG, LiClO 4, PMo 12, and Co can be used to explain that the PMo 12-Co(+ or -) nanoparticles could promote the conductivity of the PEG-LiClO4-PMo12-Co system.

Fabrication of Chemically-Modified Electrode Containing 1:12 Phosphomolybdic Anions by Sol-Gel Technique and Its Electrocatalytic Reduction of BrO_3 ^-Anions

A novel chedrically-modified electrode containing 1:12 phosphomolybdic anions wasachieved on the surface of platinum electrode by the sol-gel technique. The electrode exhibits ahigh catalytic activity towards the electroreduction of BrO3- anions.

Polyoxometalates-engineered hydrogen generation rate and durability of Pt/CNT catalysts from ammonia borane

Heterogeneously catalyzed hydrolytic dehydrogenation of ammonia borane is a remarkable structure sensitive reaction. In this work, a strategy by using polyoxometalates(POMs) as the ligands is proposed to engineer the surface and electronic properties of Pt/CNT catalysts toward the enhanced hydrogen generation rate and durability. Three kinds of POMs, i.e., silicotungstic acid(STA), phosphotungstic acid(PTA)and molybdophosphoric acid(PMA), are comparatively studied, among which the STA shows positive effects on the catalytic activity and durability. A catalyst structure-performance relationship is established by a combination of kinetic and isotopic analyses with multiple characterization techniques, such as HAADF-STEM, EDS, Raman spectroscopy and XPS. It is shown that the STA compared to the other two POMs can increase the Pt binding energy and thus promote the reaction. The insights demonstrated here could open a new avenue for boosting the reaction by employing the POMs as the ligands to engineer the catalyst electronic properties.

Catalytic oxidative desulfurization of fuels in acidic deep eutectic solvents with [(C_6H_(13))_3P(C_(14)H_(29))]_3PMo_(12)O_(40) as a catalyst

Deep eutectic solvents(DESs) are a new class of green solvents analogous to ionic liquids due to their biodegradable capacity and low cost. However, the direct extractive desulfurization of diesel oil by DESs cannot meet the government’s standard. In this work, amphiphilic polyoxometalates were synthesized and characterized by FT-IR and mass spectrometry.The oxidative desulfurization results showed that benzothiophene(BT) could be completely removed by employing a [(CH)P(CH)]PMoO, DES(ChCl/2 Ac) and HOsystem. It was also found that the organic cation of catalysts played a positive role in oxidative desulfurization. The reaction conditions, such as reaction temperature and time, the amount of catalyst and DES and HO/S(O/S) molar ratio, were optimized. Different sulfides were tested to determine the desulfurization selectivity of the optimal reaction system, and it was found that 97.2% of dibenzothiophene(DBT) could be removed followed by 80.7% of 4-MDBT and 76.0% of 4,6-DMDBT. After reaction, the IR spectra showed that the catalyst [(CH)P(CH)]PMoOwas stable during the reaction process and the oxidative product was dibenzothiophene sulfone(DBTO). Furthermore, the catalyst can be regenerated and recycled for four runs with little loss of activity.

Synthesis and Structure Investigation of a Transition Metal Ion Bridging Bis(diphosphopentamolybdates),[H_2BIIM]_3[HBIIM]_4[Mn(H_2O)_4(P_2Mo_5O_(23))_2]·7H_2O

A novel transition metal ion bridging bis（diphosphopentamolybdates） has been synthesized and characterized by elemental analysis,IR spectrum,UV spectrum and single-crystal X-ray diffraction.The single-crystal structure analysis shows that the compound consists of seven charge-compensating 2,2＇-biimidazole cations （BIIM=2,2＇-biimidazole） and one dumbbell-like [Mn（H2O）4（P2Mo5O23）2]10-heteropolyanion which is constructed by two [P2Mo5O23]6-clusters bridged through one [Mn（H2O）4]2＋ cation.

Oxidation of propane over substituted Keggin phosphomolybdate salts

Ammonium salts, （NH4）6HPMo11MO40 （M = Ni, Co, Fe）, have been investigated for the oxidation of propane, with molecular oxygen, at temperature ranging between 380 ℃ and 420 ℃ after in-situ pre-treatment performed at two heating rate of 5 or 9 ℃/min. They were characterized by BET method, XRD, 31p NMR, UV-Vis and IR techniques. The catalysts were found active in the propane oxidation and selective to propene or acrolein, in particular for samples pre-treated with the heating rate of 9 ℃/min.

Polyoxometalate-based silica-supported ionic liquids for heterogeneous oxidative desulfurization in fuels

With the aim of deep desulfurization, silica-supported polyoxometalate-based ionic liquids were successfully prepared by a one-pot hydrothermal process and employed in heterogeneous oxidative desulfurization of various sulfur compounds. The compositions and structures of the hybrid samples were characterized by various methods such as FT-IR, XPS, Raman,UV–Vis, wide-angle XRD and N2adsorption–desorption. The experimental results indicated that the hybrid materials presented a high dispersion of tungsten species and excellent catalytic activity for the removal of 4,6-dimethyldibenzothiophene without any organic solvent as extractant, and the sulfur removal could reach 100.0% under mild conditions.The catalytic performance on various substrates was also investigated in detail. After cycling seven cycles, the sulfur removal of the heterogeneous system still reached 93.0%. The GC-MS analysis results demonstrated that the sulfur compound was first adsorbed by the catalyst and subsequently oxidized to its corresponding sulfone.

Synthesis, Crystal Structure and Biological Activity of a Novel Amino Acid Salt (HGly)_4[HPMo_(12)O_(40) ]_2·22H_2O

A novel compound, (HGly) 4[HPMo 12 O 40 ] 2·22H 2O, was synthesized and characterized by means of elemental analysis, IR and X ray diffraction. The compound crystallized in a monoclinic space group Cc with a =4 0060(0 8) nm, b =1 2527(0 3) nm, c =1 9930(0 4) nm, β =96 36(3)°, V =9 940(3) nm 3, Z =2, R 1=0 0576, wR 2 =0 1746. The anti tumor activity of this compound was tested in two human tumor cell lines in vitro .

Synthesis, Electrocatalytic Properties and Crystal Structure of a New Organic-inorganic Hybrid Constructed from Dodecamolybdophosphoric Acid and Benzotriazole

A new compound, (C 6H 6N 3) 7(PMo Ⅵ 12 O 40 )(PMo ⅤMo Ⅵ 11 O 40 )·2CH 3CH 2OH·5H 2O, was synthesized and characterized by means of elemental analyses, IR spectroscopy, 1H NMR spectroscopy and single crystal \{X ray\} diffraction. This is the first example of benzotriazole polyoxometalates species. The compound crystallized in a triclinic space group P 1 with a =1 8378(4) nm, b =1 9078(4) nm, c =2 1037 (4) nm, α =\{63 41(3)°\}, β =64 31(3)°, γ =68 38(3)°, V =5 803(2) nm 3, Z =2, R 1=0 0486, wR 2=0 1357. The X ray crystallographic study showed that the crystal structure was constructed by electrostatic interactions and hydrogen bonds between dodecamolybdophosphorate anions and protonated benzotriazole cations. The electrochemical behavior and the reduction of nitrite and hydrogen peroxide electrocatalyzed by the title compound were studied.

Synthesis,Structure Characterization and Biological Activity of a Novel Amino Acid Salt(HAla)_8(H_3O)_(10)[PMo_(12)O_(40)]_6·22H_2O

A novel compound was synthesized and characterized by means of elemental analysis, IR and UV spectra, TG, CV and single crystal X-ray diffraction. The compound crystallized in an orthorhombic space group C222 with a = 1. 622 4(3) nm, b=3. 498 4(7) nm, c=l. 301 5(3) nm,V=7. 387(3) nm3, Z = 6, R1 = 0. 037 3, wR2 = 0. 114 0. The Ala (Ala = alanine) molecules were protonated at the amino nitrogen N (1) and the C (2) of Ala group with the terminal oxygen atom O(15), O(14), O(26) and O(27) of the polyoxometalates participating in the hydrogen bond network. The anti-tumor activity of the title compound was estimated against Hela and Pc-3m cancer cells.

Photocatalytic properties of thin films of ruthenium metallopolymers/gold nanoparticle: Polyoxometalate composites using visible excitation

Thin layers of an electrostatically associated adduct RuPVP-AuNP:POM formed between the polyoxomolybdate, [S2 Mo18 O62 ]4, the polycationic metallopolymer [Ru(bpy)2(PVP)10 ](ClO4)2 and DMAP-protected gold nanoparticle have been deposited onto electrodes using two separate methods, alternate immersion layer-by-layer assembly and pre-assembled drop-casting; PVP is poly(4-vinylpyridine), BPY is 2,2'-bipyridyl, and DMAP is 4-dimethylaminopyridine. Significantly, the efficiency of the photocatalysis depends markedly on the structure of the [RuPVP-AuNP:POM] even when photonic properties are very similar. Strikingly, despite their similar photonic properties, an additional optical transition is observed in UV-vis and the Raman spectra of pre-assembled drop cast [RuPVP-AuNP:POM], which was not seen in dip coated [RuPVP-AuNP:POM]. Importantly, this electronic communication enhances the photocatalytic oxidation of benzaldehyde by a factor of more than four. While there is clear evidence for photosensitisation in the drop cast not present for the dip coated systems, the magnitude of the photocurrent, i.e.,(82.2 6.6) nA·cm 2for pre-assembled drop cast [RuPVP-AuNP:POM] at a ruthenium to Au nanoparticle mole ratio of 48:1, is twice as large as that those found in [Ru-PVP:POM] film.

A New Bis-(As_3O_6) Capping 6-Molybdonickelate Complex:Preparation and Characterization of [Ni(en)_2(H_2O)]_2[(NiO_6)Mo_6O_(18)(As_3O_3)_2]·2H_2O

A new complex constructed from a unit with two As3O6 rings capping Anderson-type moieties,[Ni（en）2（H2O）2]2[（NiO6）Mo6O18（As3O3）2]·2H2O（1,en = ethylenediamine）,has been hydrothermally synthesized and characterized by IR,single-crystal X-ray diffraction and thermogra-vimetric analysis.The compound crystallizes in triclinic,space group P1 with a = 9.1230（16）,b = 11.8078（9）,c = 12.2111（9） ,α = 114.5210（10）,β = 98.0350（10）,γ = 100.0320（10）o,Mr = 2029.80,C8H44As6Mo6N8Ni3O36,V = 1145.0（2） 3,Dc = 2.944 g/cm3,Z = 1,GOF = 0.997,μ = 7.203 mm-1,F（000） = 970,R = 0.0352 and wR = 0.1019.Compound 1 consists of an Anderson-type capped by a two-ring（As3O6） unit [（NiO6）Mo6O18（As3O3）2]4-,two six-coordinate [Ni（en）2（H2O）2]2＋ cations and two water molecules.

Assembly and Electrochemical Study of Transition Metal Substituted Polyoxometalates SiW_(11)NiO_(39)^(6-) and SiW_(11)MnO_(39)^(6-) on 4-Aminothio-phenol Modified Glassy Carbon Electrode

Via layer-by-layer assembly, the polyoxometalates of Keggin type, SiW_ 11O_ 39Ni(H_2O) 6-(SiNiW_ 11) and {SiW_ 11O_ 39Mn(H_2O) 6-}(SiMnW_ 11) were first immobilized on a 4-aminothiophenol(4-ATP) modified glassy carbon electrode surface. The electrochemical behavior of these polyoxometalates was investigated. They exhibited some special properties in the films, which are different from those in a homogeneous aqueous solution. Their reaction mechanism in a multilayer film is proposed. The electrocatalytic behavior of these multilayer film electrodes for the reduction of BrO-_3 and NO-_2 were comparatively studied.

Synthesis and Crystal Structure of the Heteropolymate Compound Na_3H_2[Ce_3(H_2O)_(18)Bi_2W_(22)O_(76)]·23H_2O

A Bi(Ⅲ) contained heteropolymate compound Na3H2[Ce3(H2O)18Bi2W22O76] 23H2O 1 has been synthesized. It crystallizes in the triclinic system, space group P1 with a = 14.370(3), b = 17.113(3), c = 24.764(5) , = 74.33(3), = 77.20(3), ?= 65.29(3), V = 5285.3(18) 3, Z = 2, Mr = 6908.66, Dc = 4.341 g/cm3, F(000) = 6042, m(MoKa) = 28.543 mm-1, R = 0.0604 and wR = 0.1659 for 15788 reflections with I > 2(I). The structure analysis revealed that in the anionic framework of the title compound the [Bi2W22O76]14- anions are connected by Ce3+ and Na+ cations into a three dimensional network.