Polyoxovanadate(NH_4)_7[MnV_(13)O_(38)] as cathode material for lithium ion battery and improved electrochemical performance

The polyoxovanadate（NH4）7[MnV13O38]（AMV） was synthesized and characterized by X-ray diffraction pattern, Fourier transform infrared spectra, and field emission scanning electron microscope equipped with energy dispersive X-ray spectroscopy. In order to improve the electrochemical performance of AMV, the particle size of as-prepared AMV is decreased to nanoscale by re-precipitation in the water-ethanol solution. The results of the electrochemical impedance spectra and the 4-pin probe measurements show that the electrical conductivity of AMV is improved by decreasing the particle size. The nanoparticle AMV shows higher initial discharge capacity and energy density than the as-prepared AMV when cycled at 0.5C. On the other hand, the nanoparticle AMV exhibits higher rate capability than the as-prepared AMV.

Hydrothermal Synthesis of Polyoxovanadate-based MOFs Microsphere as Supercapacitor

Polyoxovanadate-based MOFs microsphere electrode material, [Ni_2(4,4?-bipyridine)_3(H_2O)_2V_4O_(12)]·2.5 H_2O, was synthesized through a simple hydrothermal method, and then characterized through FT-IR, XRD and SEM. Electrochemical properties of the sample as supercapacitor electrodes in aqueous electrolyte were developed and studied by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy techniques. Results showed that a high specific capacitance of 152.36 F g^(-1) at current density of 1 A g^(-1) in 2 M KOH electrolyte, and 97.62% retention after 2500 charge-discharge cycles at current density of 4 A g^(-1), which is promising for applications in supercapacitors.

Synthesis, Structure Characterization and Biological Activity of a Novel Polyoxovanadate Cluster: [NH_3(CH_2)_2NH_2(CH_2)_2NH_3]_4·[V_6~Ⅴ V_(12)~Ⅳ O_(42)(PO_4)](PO_4)·2H_2O

A new polyoxovanadate cluster, [NH_3(CH_2)_2NH_2(CH_2)_2NH_3]_4[VⅤ_6VⅣ_ 12O_ 42(PO_4)](PO_4)·2H_2O, has been synthesized and characterized by means of elemental analysis, IR spectrometry, EPR spectrometry, TG analysis and single crystal X-ray diffraction. This compound crystallizes in a monoclinic space group C2/c with a= 2.3912(5) nm, b=1.3002(3) nm, c=2.0172(4) nm, β=105.75(3)°, V=6.036(2) nm3, Z=2, R_1=0.0572, wR_2=0.1476. It has a superKeggin structure with a Keggin unit capped by six [VO_5] moieties on the pits on every side of the Keggin unit. The anti-tumor activity of the compound was estimated in three human tumor cell lines in vitro.

Hydrothermal Synthesis and Crystal Structure of a New Supramolecular Channel Framework Based on Cu Complexes and Polyoxovanadate:[Cu(I)(phen)_2]_5[HV_(15)O_(36)(Cl)]_(0.65)[H_3V_(16)O_(38)(Cl)]_(0.35)·2H_2O

A new compound [Cu（I）（phen）2]5[HV15O36（Cl）]0.65[H3V16O38（Cl）]0.35·2H2O 1 （phen = 1,10′-phenanthroline） has been prepared from the hydrothermal reaction of V2O5, CuCl, phen, H2C2O4·2H2O, THMAM （tris（hydroxymethyl）aminomethane） and H2O in the molar ratio of 3：1：1：0.5：2.5：1400. Compound 1 crystallizes in the space group P42212 of the tetragonal system with a = b = 21.5009（8）, c = 28.401（2） A, V= 13129.5（12） A^3 Z = 4, Dc = 1.800 g/cm^3, μ（MoKa） = 1.932 mm^-1, λ（MoKa） = 0.71073 A, F（000） = 7063.4, C120H81.20ClCu5N20O38.7V15.35, Mr = 3557.58, the final R = 0.0594 and wR= 0.1320 for 7761 observed reflections （I 〉 2σ（I））. Structure analysis shows that 1 exhibits a 3D channel framework formed by the supramolecular assembly of Cu complexes and polyoxovanadate clusters via intermolecular hydrogen bonding, and the channels contain Cu complexes. Other characterizations by elemental analysis, XPS, IR, XRD and thermal analysis are also described.

Hydrothermal Synthesis and Crystal Structure of a New Polyoxovanadate:[Mn(en)_3]_2en_(0.5)[HV_8~ⅤV_8~ⅣO_(38)(Cl)]·4.5H_2O(en=Ethylenediamine)

A new compound has been synthesized under hydrothermal conditions and characterized by IR, elemental analysis, XPS and single-crystal X-ray diffraction analysis. The title compound [Mn（en）3]2en0.5[HV8VV8IVO38（CI）]·4.5H2O crystallizes in monoclinic, space group C2/c, with a = 17.016（4）, b = 18.858（4）, c = 18.872（4） A, β = 93.667（4）°, V = 6043（2）A3, Z = 4, Dc = 2.242 g/cm3, Mr = 2040.12, F（000） = 4020,μ = 2.895 mm-1, Rint = 0.0921, R = 0.0649 and wR = 0.1325. Single-crystal X-ray structure analysis indicates that the title compound consists of a polyanion [HV8VV8IVO38（CI）]4- cage, two [Mn（en）3]2^2＋ cations, four and a half lattice waters and a half ethylenediamine. In addition, intermolecular O-H...N, O-H...O, N-H...O and C-H...O hydrogen bonds link the molecules together to form a three-dimensional structure.

Design and synthesis of polyoxovanadate-based framework for efficient dye degradation

A new polyoxovanadate-based framework material[Cu(en)_(2)]_(4)V_(18)O_(42)(H_(2)O)·6H_(2)O(1)was designed and synthesized by hydrothermal reaction of NaVO_(3),Cu(NO_(3))_(2)·6H_(2)O and 1,2-diaminoethane(en)via carefully adjusting the pH value of the reaction system.The structure of the title compound has been determined by single-crystal X-ray diff raction analysis,thermogravimetric analysis,infrared spectra and elemental analysis.Detail structural analysis demonstrate the three-dimensional(3D)framework structure of compound 1,which was composed of the[V_(18)O_(42)(H_(2)O)]_(8)−({V_(18)O_(42)(H_(2)O)})anions linked by the Cu^(2+)cations.Compound 1 represents the fi rst 3D framework based on{V_(18)O_(42)(H_(2)O)}polyoxoanions and copper complexes.Solar-driven degradation of residual organic pollutants in industrial wastewater is still a major problem for human beings.Photocatalytic experiments reveal that compound 1 possesses of excellent photocatalytic activity for the degradation of methylene blue and rhodamine B.

26-electrons redox-active polyoxovanadate clusters for aqueous zincion batteries

Aqueous zinc-ion batteries(ZIBs)are attaining increasing attention for their high safety and low cost.Despite significant progresses in realizing high-performance cathode material for ZIBs,simultaneously endowing them with high capacity and fast-charging capability,the long-term cycling stability remains a major unsolved challenge.In this work,a polyoxovanadate cluster of(NH_(4))_(8)[V_(19)O_(41)(OH)_(9)]·11H_(2)O(NOV)is defined as a cathode material for ZIBs that contains mixed-valence vanadium sites(V^(4+)and V^(5+)).A maximum of 26 electrons can be accommodated in one[V_(19)O_(41)(OH)_(9)]^(8-){V_(19)O_(50)}cluster,contributing to the high theoretical specific capacity of 328 mA·h·g^(-1).The Ti_(3)C_(2)T_(x) MXene nanosheets are incorporated into NOV with the help of ionic liquid(IL)linkers to restrain the dissolution of vanadium species and facilitate electron transport across the electrode.The interfacial bonding,anion exchange,and electrostatic interactions among NOV and MXene are provided by IL liquid.The nanohybrid of NOV-IL-MXene endows excellent contact between MXene and NOV,thereby enhanced charge transfer is observed at interface.Subsequently,the as-synthesized NOV-IL-MXene cathodes exhibit high discharge capacity of 413 mA·h·g^(-1) at 0.2 A·g^(-1) even at high mass loading of 5.2 mg·cm^(-2),remarkable rate performance of 182 mA·h·g^(-1) at 10 A·g^(-1),and impressive cycling stability of 94%capacity retention after 2000 cycles.This work opens up new opportunities to develop advanced polyoxovanadate hybrid cathodes for low-cost and high-performance aqueous ZIBs.

Weak interaction-steered evolution of polyoxovanadate-based metal-organic polyhedra from transformation via interlock to packing

A bottleneck in biomimetic synthesis consists in the full copy of,for example,the hierarchical structure of proteins directed by weak interactions.By contrast with covalent bonds bearing definite orientation and high stability,weak intermolecular forces within a continuous dynamic equilibrium can be hardly tamed for molecular design.In this endeavor,a ligand-dominated strategy that embodies tunable electrostatic repulsion andπ···πstacking was first employed to shape polyoxovanadate-based metal-organic polyhedra(VMOPs).Structural evolution involving transformation,interlock,and discovery of an unprecedented prototype of the Star of David was hence achievable.Not only as a handy tool for the primary structural control over VMOPs,these weak forces allow for an advanced management on the spatial distribution of such manmade macromolecules as well as the associated physicochemical behaviors,representing an ideal model for simulating and interpreting the conformation-function relationship of proteins.

Reducing obesity and inflammation in mice with organically-derivatized polyoxovanadate clusters

Obesity,characterized by the dysregulation of energy balance in adipose tissue and other metabolic organs,is frequently accompanied by chronic low-grade inflammation.As long-acting insulin sensitizers,the organically-derivatized polyoxovanadates(POVs),can extend the dosing interval of antidiabetic drugs from hourly to almost daily.In this work,the protective activity of POVs is investigated by an eight-week in vivo experiment,in which a small amount of POVs was administrated orally to a mouse model of dietinduced obesity every day.The present study shows that administration of POVs significantly decreases the body weight of mice,reduces adipose tissue accumulation,and simultaneously reduces adipose tissue inflammation.In addition,the anti-obesogenic population of i NKT cells is protected potentially by POVs,which subsequently alleviates visceral adipose tissue inflammation in high-fat-diet(HFD)-fed mice against diet-induced obesity.By contrast,the change in body weight after POV treatment is the result of a substantial reduction in fat mass,with no obvious effects on lean body mass.These findings demonstrate that supplementary of POVs would be an effective way to combat obesity and metabolic disorders while lowering metabolic inflammation.

Polyoxovanadate-based metal-organic frameworks consisted of open vanadium sites for selective catalytic oxidation of sulfides

Three novel polyoxovanadate-based metal-organic frameworks(POV-MOFs),[Co_(2)(1,4-dtzb)_(3)]{V_(4)O_(12)}(V-Co-MOF_(1),1,4-dtzb=1,4-di(4H-1,2,4-triazol-4-yl)benzene],[Co_(3)(1,3-dtzb)_(2)][{V_(6)O_(18)}(V-Co-MOF_(2),1,3-dtzb=1,3-di(4H-1,2,4-triazol-4-yl)benzene],[Co_(4)(4,4’-bdtzb)_(2)]{V_(8)O_(24)}(V-Co-MOF_(3),4,4’-bdtzb=4,4’-(1,1’-biphenyl)-4,4’-diylbis(4H-1,2,4-triazole)benzene]were facilely synthesized and structurally characterized.Single-crystal X-ray diffraction analysis indicates that all the POV-MOFs possess open V sites lined on POV clusters of{V_(4)O_(12)}/{V_(6)O_(18)}/{V_(8)O_(24)}that uniformly distribute on the robust three-dimensional frameworks.This unique structural feature allows them to show high performance for sulfidesulfoxide transformation when performing the reaction in MeOH at 50℃ for 45 min using H_(2)O_(2) as green oxidant.Notably,V-Co-MOF1 exhibited the highest catalytic efficiency,with a conversion>99% and selectivity up to 97% for a series of sulfide substrates.Control reaction demonstrated the catalytically active centers are the open V sites while the MOF skeleton constructed from Co^(2+)and ligands also contributes to enhance the conversion and selectivity via synergistic effect.Furthermore,V-Co-MOF1 can be used as a stable heterogeneous catalyst,and both the structural integrity and catalytic performance were well reserved after five cycles,demonstrating their great potential for advanced catalytic oxidation.

Polyoxovanadate-based MOFs Microsphere Constructed from 3-D Discrete Nano-sheets as Supercapacitor

A novel polyoxovanadate-based MOFs microsphere,[Ni(phen)V2O7]·H2O(phen=1,10-phenanthroline),constructed from 3-D discrete nano-sheets has been prepared and characterized by XRD,FT-IR,SEM and TEM.Electrochemical properties as supercapacitor of the as-prepared sample,such as CV,EIS,GCD and the cycle life test have also been studied.The as-prepared MOF(V,Ni)showed a high specific capacitance of 178.09 F×g^(-1) at 1 A×g^(-1) as well as good cycling stability and coulombic efficiency.This work proved that the novel MOFs based on polyoxovanadate hybrid material may serve as a promising electrode material for high-performance supercapacitor.

Synthesis and Structure of a Novel Organic-Inorganic Hybrid Polyoxovanadate, [Ni（bpp）2]2（V4O12） （bpp= 1,3-bi-4-pyridylpropane）

A novel organic-inorganic hybrid polyoxovanadate, [Ni（bpp）2]2（V4O12） （bpp= 1,3-bi-4-pyridylpropane）, was hydrothermally synthesized from a mix.ture of NiCl2＊6H2O, NH4VO3, bpp, EtOH and H2O. The crystal structure consists of ∞^2[Ni（bpp）2]^2＋, two-dimensional networks interpenetrating perpendicularly with each other, and （V4O12）^4-, cyclic tetranuclear clusters linking the ∞^2[Ni（bpp）2]^2＋ networks to form a three-dimensional coordination framework. The crystal belongs to tetragonal space group I41/a with unit cell parameters, a= 2.14705 nm, c= 1.29293 nm. UV-Vis-NIR reflectance spectroscopy study revealed insulator nature for the crystal with an optical energy gap of 2.70 eV.

Sulfonate-Functionalized Polyoxovanadate-Based Metal-Organic Polyhedra for Enhanced Proton Conduction via the Synergy of Linker and Metal Cluster Vertex

Metal-organic polyhedra(MOPs)have emerged as novel porous platforms for proton conduction,however,the concerted employment of both linker and metal cluster vertex is rarely applied for the fabrication of MOPs-based high conducting materials.Herein we report the synthesis of sulfonate-functionalized polyoxovanadate-based MOPs for enhanced proton conduction via the synergistic effect from linker and metal cluster node.MOPs 1 and 2 exhibit octahedral cage configuration constructed from{V_(5)O_(9)Cl}vertex and 5-sulfoisophthalate linker.Owing to the ordered packing of octahedral cages along three axes,3D interpenetrated open channels that are lined with high-density sulfonates are thus formed within 2.Coupled with the proton-conductive{V_(5)O_(9)Cl}vertexs as well as protonated counterions,an extensive H-bonded network is therefore generated for facile proton transfer.2 exhibits high proton conductivity of 3.02×10^(-2)S cm^(-1)at 65℃under 90%RH,recording the highest value for MOPs pellet sample.This value is enhanced~1order of magnitude compared with that of carboxylate-functionalized analogue 3,clearly illustrating the advantage of combining linker and metal cluster node for enhanced proton conduction.This work will further promote the exploitation of high proton conductive MOPs-based materials by the synergy design strategy.

Syntheses and Structures of Three Hybrid Materials Using Vanadium Polyoxoanions and Macrocyclic Copper Complex as Building Blocks

The reactions of the four-coordinated macrocyclic copper complex [CuL]（ClO4）2（L = 1,4,8,11-tetraazacyclotetradecane） with NH4VO3 under different conditions gave three inorganic-organic hybrid materials of [CuL][VO3]2·2.33H2O（1）, [CuL]3[V（10）O（28）]·8H2O（2） and [Cu L]3[V6O（18）]·8H2O（3）. Single-crystal X-ray diffraction analyses reveal that three diverse vanadium polyoxoanions, [V6O（18）]6- ring, [V（10）O（28）]6- cluster, and [V（12）O（35）]^10- ring, were isolated from the same reactant NH4VO3 under different conditions. The [CuL]^2＋ bridges the [V10O28]6- clusters to form a two-dimensional sheet in 2, and link the [V6O（18）]^6- rings in 1 and [V（12）O（35）]^10- rings in 3 into three-dimensional frameworks, respectively.

Hydrothermal Synthesis and Characterization of [V_(16)O_(38)(Cl)][Cu(enMe)_2]_(3.5)·2H_2O Containing {V_(16)O_(38)} Cluster

Compound [V_ 16 O_ 38 (Cl)][Cu(enMe)_2]_ 3.5 ·2H_2O(1) has been hydrothermally synthesized and characterized by means of single-crystal X-ray diffraction,elemental analysis,IR,EPR and TGA analysis. The X-ray crystallography shows that compound 1 contains a new {V_ 16 O_ 38 } cluster shell,which is connected by [Cu(enMe)_2] 2+ coordination fragments into a 3-D framework. The compound crystallized in a monoclinic system with space group P2(1)/n,M =2235.82,a =1.26076(3) nm,b =2.55802(6) nm,c =2.14742(4) nm,β =90.7380(10)°, V =6.9250(3) nm 3,Z =4,F (000)=4418,D _c=2.145 g·cm -3 , μ =3.227 mm -1 ,( Δ/σ )=0.000,S =1.066.

12-Ring Network Coordination Polymer——{[Cu(C_4N_2H_(10))_4]_2·H_4V_4O_(14)}_n Formed by Linking cyclo-[H_4V_4O_(14)]^(4-) with Cu(C_4N_2H_(10))^(2+)_4 Cation Clusters

A novel 12-ring network coordination polymer, { [ Cu （ C4 N2 H10 ） 4 ]2 H4 V4 O14 } n （ denoted as QUST-4）, was hydrothermally synthesized and structurally determined by X-ray single-crystal diffraction analysis. QUST-4 was crystallized in a monoelinic system with space group P21/n. The parameters of the unit cell are a = 1. 0497（2） nm, b = 1.6728（3） nm, c=1.2857（3） nm, 3=94. 14（3）°, V=2.2517（8） nm^3, Z=4, Dcal = 1.841 Mg/m^3, R1 = 0. 1071, and wR3 =0. 2703. The largest difference peak and hole were 2284 and - 1040 c/nm^3, respectively. The SBU（ secondary building unit） of QUST-4 was a new cyclo- aggregate of polyoxovanadate cyelo-[ S4V4O14 ]^4 - , different from cyclo-[ V4O12 ]^4-, which was condensed from two tetrahedral and two trigonal bipyramids via ahernate arrangement. Cu（piper） 4 （ piper = piperazine ） group connected the cyclo- [ H4 V4 O14 ] ^4 - anions to form the 12-ring network. The adjacent layers were linked by van der Walls forces.

Hydrothermal Synthesis and Structure of a Novel Two-dimensional Complex:[Ni_(0.5)(H_2O)_(1.5){Ni(en)_2}_3V_(18)O_(42)(Cl)]3.5H_2O

A novel two-dimensional compound [Ni0.5(H2O)1.5{Ni(en)2}3V18O42(Cl)]3.5H2O 1 has been hydrothermally synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction analysis. Crystal data for 1: monoclinic, space group C2/c with a = 12.824(3), b = 27.873(6), c = 21.092(4) , b = 92.93(3), V = 7529(3) 3, Z = 4, Dc = 2.012 g/cm3, Mr = 2280.56, F(000) = 4476 and m = 3.092 mm-1. The final R and wR are 0.0769 and 0.1783, respectively for 4203 observed reflections with I>2s(I). The structure consists of [V18O42(Cl)]7- clusters linked by trans- {Ni(en)2} groups into linear chains, while cis-{Ni(en)2} groups provide the cross-linking adjacent chains to form a two-dimensional structure.

Hydrothermal Synthesis and Crystal Structure of a New 2D Layer Compound [{Ni(en)_2}_2Sb_8V_(14)O_(42)]·5.5H_2O

A new compound based on polyoxovanadate [{Ni（en）2}2Sb8V14O42]·5.5H2O（en=ethylenediamine）（1） was synthesised hydrothermally as black rhombus crystals.Compound 1 crystallized in the monoclinic system with space group P21/n,Z=4,a=1.46953（9） nm,b=1.28623（8） nm,c=1.76008（11） nm,β=105.7230（10）°.In the asymmetric unit,cluster {Sb8V14O42} can be considered as an Sb derivative of the {V18O42} unit.Each {Sb8V14O42} cluster as a building block interconnected to four other neighboring units by {Ni（en）2} bridging groups which are linked through the terminal oxygen atoms of the polyoxoanions,forming a two dimensional network.

Preparation, Characterization and Crystal Structure Determination of (C_6H_(14)N)_5(V_5O_(15))

A 1D chain-like organic/inorganic composite material with polyoxovanadates serving as building blocks has been synthesized by the reaction of cyclohexylamine with vana- dium pentoxide, and characterized by IR, UV spectra and TG-DTA technique. The title compound (C30H70N5O15V5, Mr = 995.61) crystallizes in orthorhombic, space group P212121 with a = 6.0093(12), b = 26.780(5), c = 27.979(6) ? V = 4502.6(16) 3, Z = 4, Dc = 1.461 g/cm3, F(000) = 2060, = 1.063 mm-1, R = 0.0651 and wR = 0.1084 for 3426 observed reflections (I > 2(I)). Single-crystal X-ray structural analysis indicates that the title compound consists of five proto- nated cyclohexylamine molecules and a polyoxovanadate anion of V5O155-. In addition, the results of IR spectra and single-crystal X-ray diffraction exhibit that there exists comparatively stronger interaction between the organic groups and polyoxovanadate anion in solid state. Adjacent structure units are bridged through corner-sharing oxygen atoms of VO4 tetrahedra to construct a novel one-dimensional zigzag infinite linear chain arrangement. The curves of TG- DTA elucidate that the process of weight loss of the title compound is divided into two stages, and also reveal that the framework of polyoxovanadate anion decomposes at 473.0 ℃.

Sub-nanosized vanadate hybrid clusters maintain glucose homeostasis and restore treatment response in inflammatory disease in obese mice

Obesity is closely related with insulin resistance and chronic inflammation.Here,we report that unsaturated lipid-modified polyoxovanadates(ULPOVs)can restrict weight gain of diet-induced obese mice and improve their glycemic control and obesity-associated inflammation.Oral administration of the sub-nanosized ULPOVs at a low dosage for 7 weeks reduces the body weight and almost normalizes the blood glucose levels of obese mice fed on a high-fat diet.ULPOV treatment increases the activity of the nuclear receptor peroxisome proliferator-activated receptorγ(PPARγ)and reduces intestinal caloric intake,which may be the main reason for blood sugar and body weight control.In addition to insulin-sensitizing,PPARγactivation induced by ULPOV treatment in obese mice with atopic dermatitis(AD)promotes the type 2 T helper(TH_(2))cell selective responses and therapeutic effects on immune dysregulation caused by obesity.These data suggest sub-nanosized polyoxovanadate clusters as a class of potential candidates to relieve symptoms accompanied by diet-induced obesity.