Thermochemical charge generation in polymer-salt films as a function of temperature

Potential was studied as a function of temperature during charge generation in poly(vinyl alcohol) films containing ammonium heptamolybdate, copper nitrate, and polyoxometalate (NH₄)₄₂[Mo ₇₂ ^VI Mo ₆₀ ^V O₃₇₂(HCOO)₃₀(H₂O)₇₂] · 30HCOONH₄ · 250H₂O. The range of the strongest charge generation and its bounds were determined. The results are matched to thermal analysis data. Charge generation correlates with evolution of volatiles from the films.     

Molybdenum polyoxometalate buckyballs containing monochloroacetate groups and polymer compositions on their base

Molybdenum polyoxometalate buckyballs (NH₄)₄₂[MO₇₂^VIMO₆₀^VO₃₇₂(ClCH₂COO)₃₀(H₂O)₇₂] · 250H₂O · 15ClCH₂COONa (Mo132Cl) were synthesized; some of their properties were studied, namely, purity, spectral and crystallographic parameters, buckyball aggregation in solution, and interaction with water-soluble nonionic polymers (poly(vinyl alcohol) and poly(vinylpyrrolidone)). The newly synthesized polyoxometalate was shown to have a lower stability than its analogue containing acetate instead of chloroacetate groups, both having similar thermal destruction pathways. At the first heating steps, water is eliminated from Mo132Cl. Thermal destruction at higher temperature produces chloroacetamide, chloroacetonitrile, and other compounds.     

Thermal behavior of polyoxometalate Mo132

Thermal destruction of (NH₄)₄₂[Mo ₇₂ ^VI Mo ₆₀ ^V O₃₇₂(H₃CCOO)₃₀(H₂O)₇₂]30H₃CCOONH₄ · 250H₂O, polyoxometalate Mo132, was analyzed. Differential scanning calorimetry (DSC) and mass spectrometry were investigative tools. Thermal destruction occurs in air and in nitrogen in three main stages. First, water is eliminated. The thermolysis products at higher temperatures include acetamide and acetonitrile. Molybdenum oxides are formed in solid products through an amorphous stage. The utility of NMR spectroscopy for analyzing poly(oxometalates) is demonstrated.     

The kinetics of photochemical processes in polymer-salt systems

The kinetics of photochemical reactions in aqueous polymer-salt systems containing ammonium heptamolybdate, dodecatungstate, or metavanadate and polyvinyl alcohol or polyvinylpyrrolidone was studied by measurements of photoinduced electrode potential difference. The rate of primary accumulation of reduced d metal forms was evaluated for different systems. Possible reasons for complex oscillatory processes in the systems were analyzed. Comparative data were obtained for compositions containing polyoxometallate shaped like buckyball:(NH₄)₄₂[Mo₇₂^VIMo₆₀^VO₃₇₂(HCOO)₃₀(H₂O)₇₂] · 30HCOONH₄ · 250H₂O. UV irradiation of this system caused the oxidation of molybdenum(V). Original Russian Text ? A.A. Ostroushko, M.Yu. Sennikov, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 1, pp. 127–131.     

New data for molybdenum polyoxometallate with the buckyball structure containing acetate groups and compositions based thereon

Synthesis and characterization of the polyoxometallate (NH₄)₄₂[Mo₇₂^VIMo₆₀^VO₃₇₂(H₃CCOO)₃₀(H₂O)₇₂]30H₃CCOONH₄ · 250H₂O (Mo132) with the buckyball structure were carried out. New crystallographic data were obtained. Stability of Mo132 was studied as a function of external factors, acidity, concentration of the solution, and the presence of a polymeric component. The composition of the most stable complexes of buckyballs with polymers was confirmed. The aggregation of buckyballs in the presence of polyvinylpyrrolidone were studied. Thermochemical studies of Mo132 interaction with polyvinyl alcohol in films were carried out. Electromigration of polymer-salt complexes in solutions was established, the possibility of change of the sign of associates upon interaction of Mo132 anions with lanthanum cations was confirmed.     

Interaction of polyoxometalate Mo132 with poly(vinyl alcohol)

Some aspects of the interaction of (NH₄)₄₂[Mo ₇₂ ^VI Mo ₆₀ ^V O₃₇₂(H₃CCOO)₃₀(H₂O)₇₂] · 30H₃CCOONH₄ · 250H₂O (polyoxometalate Mo132) with a water-soluble nonionic polymer (poly(vinyl alcohol) or related poly(vinylpyrrolidone)) were studied in aqueous solutions and in films. A set of methods was used: spectrophotometry, EPR spectroscopy, visual microscopy, X-ray powder diffraction, scanning probe microscopy, and potentiometry. The complex-formation features of the system were revealed. The miscibility of the components and their influence on crystallization phenomena were considered. The effect of UV and X-rays on poly(vinyl alcohol) + polyoxometalate films was studied. Poly(vinyl alcohol) stabilizes the polymer. Mutual radiation and thermal stabilization of the polymer and polyoxometalate was discovered. The utility of ion-sensitive electrodes for Mo132 determination in solution was demonstrated.     

Two-dimensional layer polyoxometalate-based inorganic metal–organic hybrid supramolecular networks woven by Cu ··· Opolyoxoanion short contact weak interactions

Two polyoxometalate-based inorganic metal-organic hybrid supramolecular complexes [Cu(2,2′-bpy)₂]₂[V^IV ₂Mo^V ₅Mo^VI ₇O₃₈(PO₄)] (1) (2,2′-bpy?=?2,2′-bipyridine) and [Cu(2,2′-bpy)₂]₂[Mo^VMo^VI ₁₁O₃₆(PO₄)]?·?3H₂O (2), have been hydrothermally prepared and structurally characterized by single-crystal X-ray diffraction. Both complexes are constructed from polyoxoanions (the bivanadyl capped α-Keggin polymolybdate anion [V^IV ₂Mo^V ₅Mo^VI ₇O₃₈(PO₄)]^4? for 1 and the reduced 12-molybdophosphate anion [Mo^VMo^VI ₁₁O₃₆(PO₄)]^4? for 2) and copper(II) complex cations [Cu(2,2′-bpy)₂]²⁺, forming two-dimensional (2D) layer network structures, in which the polyoxoanion and the complex fragment cation connect with each other through Cu?···?O_polyoxoanion short contact weak interactions, which mediate ferromagnetic interaction.     

An organic‐inorganic heterogeneous catalyst based on Keplerate polyoxometalates for oxidation of dibenzothiophene derivatives with Hydrogen peroxide

An organic‐inorganic material (NH₄)₂(MimAM)₄₀[Mo₁₃₂O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] have been synthesized by reacting [(NH₄)₄₂[Mo^VI₇₂ Mo^V₆₀O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] with the ionic liquid 3‐Aminoethyl‐1‐methylimidazolium bromide. The catalyst showed remarkably a high catalytic performance in the oxidation of dibenzothiophene (DBT) derivatives with H₂O₂ 35% as a safe and green oxidant. The main parameters affecting the process including catalyst, acid additive, hydrogen peroxide amounts and temperature have been investigated in detail. Sulfur removal of DBT in n‐heptane reached to 98.3% yield at 40 °C using 2.5 mmol H₂O₂ and 100 mg of (NH₄)₂(MimAM)₄₀[Mo₁₃₂O₃₇₂(CH₃COO)₃₀(H₂O)₇₂] after 90 min. Under the optimal conditions, BT (benzothiophene), DBT (dibenzothiophene) and 4,6‐DMDBT (4,6‐dimethyl‐dibenzothiophene) achieved high desulfurization efficiency. Our results showed that the reactivity order of different model sulfur compounds are thiophene <4,6‐dimethyl dibenzothiophene< dibenzothiophene. The catalysts could be easily separated from the reaction solution by simple filtration and recycled for several times without loss of activity.     

Polythermal study of electrophysical characteristics of poly(vinyl alcohol) polymer-salt films

Dielectric constant, dielectric loss tangent, and electrical conductivity were studied as functions of temperature for poly(vinyl alcohol) (PVA) films doped with ammonium metavanadate or polyoxometalate Mo132: (NH₄)₄₂[Mo ₇₂ ^VI Mo ₆₀ ^V O₃₇₂(HCOO)₃₀(H₂O)₇₂]30HCOONH₄·250H₂O. The electrophysical characteristics were measured and analyzed as dependent on the concentration and nature of the salt component and ambient humidity. The conductivity of polymer-salt compositions as a function of salt component concentration has a maximum, which is typical of electrolyte solutions. A conductivity mechanism was suggested: electron conductivity due to radical species at relatively low temperatures and proton conductivity at higher temperatures. Inflections on the electrical conductivity versus temperature and other property plots are due to removal of water from the compositions and thermal destruction.     

钼钒磷杂多酸铵蓝的合成和性质研究

本实验采用分步加原料的方法，以不同的磷钼钒比，直接合成了三种１：１２系列的钼钒磷杂多酸铵蓝，即（ＮＨ４）４Ｈ２·１５Ｈ２Ｏ（ｂｌｕｃ—１），（ＮＨ４）５Ｈ２·和（ＮＨ４）６Ｈ２·３０Ｈ２Ｏ（ｂｌｕｃ－３），并研究了反应条件对这些钼钒磷杂多酸铵蓝形成的影响．通过元素分析、电位滴定、电子光谱和Ｘ射线衍射等测试手段研究了配合物的性质，并确定了配合物的组成．     

A New Molybdophosphate Constructed From {Mo<Stack><Subscript>2</Subscript><Superscript>V</Superscript></Stack>O<Subscript>4</Subscript>(H<Subscript>2</Subscript>O)<Subscript>6</Subscript>}<Superscript>2+</Superscript> and 1-Hydroxyethylidenediphosphonate

A new molybdophosphate (NH₄)₈{Mo₂^VO₄[(Mo₂^VIO₆)CH₃C(O)(PO₃)₂]₂}·14H₂O (1), has been synthesized by the reaction of {Mo₂^VO₄(H₂O)₆}²⁺ fragments with 1-hydroxyethylidenediphosphonate (hedp HOC(CH₃)(PO₃H₂)₂), and it is characterized by ³¹P NMR, IR, UV, element analysis, TG and single-crystal X-ray analysis. The structure analysis reveals that the polyoxoanion can be described as two {(Mo₂^VIO₆)(CH₃C(O)(PO₃)₂} units connected by a {Mo₂^VO₄}²⁺ moiety. In the structure, the six Mo atoms are arranged into a new “W-shaped” structure, which represents a new kind of molybdophosphate.     

Molybdenum Bisphosphonates with Cr(III) or Mn(III) Ions

The synthesis of Mo^VI bisphosphonates (BPs) complexes in the presence of a heterometallic element has been studied. Two different BPs have been used, the alendronate ligand, [O₃PC(C₃H₆NH₃)(O)PO₃]^4? (Ale) and a new BP derivative with a pyridine ring linked to the amino group, [O₃PC(C₃H₆NH₂CH₂C₅H₄N)(O)PO₃]^4? (AlePy). Three compounds have been isolated, a tetranuclear Mo^VI complex with Cr^III ions, (NH₄)₅[(Mo₂O₆)₂(O₃PC(C₃H₆NH₃)(O)PO₃)₂Cr]·11H₂O (Mo₄(Ale)₂Cr), its Mn^III analogue, (NH₄)_4.5Na_0.5[(Mo₂O₆)₂(O₃PC(C₃H₆NH₃)(O)PO₃)₂Mn]·9H₂O (Mo₄(Ale)₂Mn), and a cocrystal of two polyoxomolybdates, (NH₄)₁₀Na₃[(Mo₂O₆)₂(O₃PC(C₃H₆NH₂CH₂C₅H₄N)(O)PO₃)₂Cr]₂[CrMo₆(OH)₆O₁₈]·37H₂O ([Mo₄(AlePy)₂Cr]₂[CrMo₆]). In this latter compound an Anderson-type POM [CrMo₆(OH)₆O₁₈]^3? is sandwiched between two tetranuclear Mo^VI complexes with AlePy ligands. The protonated triply bridging oxygen atoms bound to the central Cr^III ion of the Anderson anion develop strong hydrogen bonding interactions with the oxygen atoms of the bisphosphonate complexes. The UV–Vis spectra confirm the coexistence in solution of both POMs. Cyclic voltammetry experiments have been performed, showing the reduction of the Mo centers. In strong contrast with the reported Mo^VI BP systems, the presence of trivalent cations in close proximity to the Mo^VI centers dramatically impact the potential solid-state photochromic properties of these compounds.     

New Perspectives in Polyoxometalate Chemistry by isolation of compounds containing very large moieties as transferable building blocks: (NMe4)5[As2Mo8V4AsO40] · 3H2O, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] · 65 H2O, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] · 14 H2O,and (NH4)12[Mo36(NO)4O108(H2O)16] · 33 H2O

The compounds (NMe₄)₅[As₂Mo₈V₄AsO₄₀] · 3 H₂O 2a , (NH₄)₂₁[H₃Mo₅₇V₆(NO)₆O₁₈₃(H₂O)₁₈] · 65 H₂O 3a , (NH₂Me₂)₁₈(NH₄)₆[Mo₅₇V₆(NO)₆O₁₈₃(H₂O)₁₈] · 14 H₂O 3b and (NH₄)₁₂[Mo₃₆(NO)₄O₁₀₈(H₂O)₁₆] · 33 H₂O 4a ( 3a and 4a were not correctly reported in the literature regarding to their composition, structures and the oxidation states of the metal centres) which contain large isolated anionic species, have been prepared (among them 3a, 3b , and 4a in rather high yield) and characterized by complete crystal structure analysis as well as IR/Raman, UV/VIS/NIR, ESR spectroscopy and magnetic susceptibility measurements, redox titrations, bond valence sum calculations, elemental analyses and thermogravimetric studies. Perspectives for polyoxometalate chemistry referring to the synthesis of “extremely” large nanoscaled species are discussed, together with the occurrence of a large transferable {Mo₁₇} building block in the compounds 3a, 3b and 4a which also exists in the corresponding iron compound Na₃(NH₄)₁₂[H₁₅Mo₅₇Fe₆(NO)₆O₁₈₃(H₂O)₁₈] · 76 H₂O 7a .     

Another application of (NH4)42[MoVI72MoV60O372(CH3COO)30(H2O)72] as a highly efficient recyclable catalyst for the synthesis of dihydropyrano[3,2‐c]chromenes

In continuation of our previous works on the application of (NH₄)₄₂[Mo^VI₇₂Mo^V₆₀O₃₇₂(CH₃COO)₃₀(H₂O)₇₂], a Keplerate‐type giant‐ball nanoporous isopolyoxomolybdate, as a catalyst for the synthesis of heterocyclic compounds, in this paper, we report another application of this attractive catalyst in the synthesis of 2‐amino‐5‐oxo‐4,5‐dihydropyrano[3,2‐c]chromene‐3‐carbonitriles via a one‐pot three‐component reaction of 4‐hydroxycoumarin, aldehydes and malononitrile. The reactions occur in ethanol–water as solvent at room temperature and the process is operative with various aldehydes, giving the corresponding products in high yields. Other beneficial features of this protocol include short reaction times, simple work‐up and the recyclability and reusability of the catalyst for up to five consecutive runs. Copyright © 2016 John Wiley & Sons, Ltd.     

Two organic–inorganic hybrid compounds constructed from [PMoV1MoVI7VIV2VV4O42]4− and different transition metal fragments

Two new organic–inorganic hybrid compounds, [Cu(phen)(prz)]₂[PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂]·4H₂O (1) and [Ag₂(phen)₄]₂[PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂] (2) (phen = 1,10-phenanthroline, prz = pyrazine), have been synthesized and characterized by IR, XPS, XRD, UV–vis, fluorescent spectra analyses, elemental analyses, X-ray diffraction analyses, TG analyses, and cyclic voltammetric measurements. Both compounds are formed by Keggin POM cores and transition metal fragments. Compound 1 exhibits an unprecedented 1-D chain structure constructed from [PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂]^4? and [Cu(phen)(prz)]²⁺ in the –A–B↑–C–B↓– linking mode. Compound 2 shows a supramolecular structure formed by [PMo^V₁Mo^VI₇V^IV₂V^V₄O₄₂]^4? and [Ag₂(phen)₄]²⁺.     

Controlling the Self‐Assembly of a Mixed‐Metal Mo/V–Selenite Family of Polyoxometalates

Five mixed‐metal mixed‐valence Mo/V polyoxoanions, templated by the pyramidal SeO₃^2? heteroanion have been isolated: K₁₀[Mo^VI₁₂V^V₁₀O₅₈(SeO₃)₈]?18 H₂O ( 1 ), K₇[Mo^VI₁₁V^V₅V^IV₂O₅₂(SeO₃)]?31 H₂O ( 2 ), (NH₄)₇K₃[Mo^VI₁₁V^V₅V^IV₂O₅₂(SeO₃)(Mo^V₆V^V‐ O₂₂)]?40 H₂O ( 3 ), (NH₄)₁₉K₃[Mo^VI₂₀V^V₁₂V^IV₄O₉₉(SeO₃)₁₀]?36 H₂O ( 4 ) and [Na₃(H₂O)₅{Mo_18?xV_xO₅₂(SeO₃)} {Mo_9?yV_yO₂₄(SeO₃)₄}] ( 5 ). All five compounds were characterised by single‐crystal X‐ray structure analysis, TGA, UV/Vis and FT‐IR spectroscopy, redox titrations, and elemental and flame atomic absorption spectroscopy (FAAS) analysis. X‐ray studies revealed two novel coordination modes for the selenite anion in compounds 1 and 4 showing η,μ and μ,μ coordination motifs. Compounds 1 and 2 were characterised in solution by using high‐resolution ESI‐MS. The ESI‐MS spectra of these compounds revealed characteristic patterns showing distribution envelopes corresponding to 2? and 3? anionic charge states. Also, the isolation of these compounds shows that it may be possible to direct the self‐assembly process of the mixed‐metal systems by controlling the interplay between the cation “shrink‐wrapping” effect, the non‐conventional geometry of the selenite anion and fine adjustment of the experimental variables. Also a detailed IR spectroscopic analysis unveiled a simple way to identify the type of coordination mode of the selenite anions present in POM‐based architectures.     

Effect of the central metal on coordination of 1,10-phenanthroline-5,6-dione in Keggin-based hybrid compounds

Two new Keggin-based hybrid compounds, [Cu₂(pdon)₃][PMo^VI ₁₁Mo^VO₄₀]·3H₂O (1) and [Mn₂Cl(H₂O)₂(pdon)₄][PMo₁₂O₄₀]·2H₂O (2) (pdon = l, l0-phenanthroline-5,6-dione) (pdon), were synthesized under hydrothermal conditions. By using different metal ions and tuning the ratio of metal to ligand, pdon shows different coordination modes. In compound 1, pdon with three kinds of coordination modes link Cu^II ions to form a 1D wave chain and Keggin-type polyanions [PMo^VI ₁₁Mo^VO₄₀]^4? fringe this 1D chain; hydrogen bonding interactions extend these 1D chains into a 2D supramolecular network. Compound 2 exhibits a discrete structure, in which pdon shows a single chelating coordination. Electrochemical properties of the title compounds have been investigated.     

A new α-keggin unit coordinated to two cobalt complex moieties {PMoVI 11MovO40[Co(TATP)2(H2O)]2}·4H2O

A new α-Keggin unit supported transition metal complex, {PMo^VI ₁₁Mo^VO₄₀ [Co(TATP)₂(H₂0)]₂}?·?4H₂O (1) (TATP?=?1,4,8,9-tetranitrogen-trisphene), has been hydrothermally synthesized and characterized by single crystal X-ray diffraction. X-Ray analysis showed that the two [Co(TATP)₂(H₂O)] units are covalently bonded to the α-Keggin unit [PMo^VI ₁₁Mo^V04o]^4? via the terminal oxygen atoms. 1 represents the α-Keggin type polyoxoanion coordinated with two transition metal complex moieties, which further acts as a neutral molecular unit to construct an interesting 3D supramolecualr framework.     

Hydrothermal synthesis and structural characterization of two new reduced phosphomolybdates based on an organoamine template and copper ion

Two new compounds, (H₂en)₃(H₂enMe)₄(H₃O){Cu^I[Mo^V ₆O₁₂(OH)₃(HPO₄)(PO₄)₃]₂}?·?6H₂O (1) and (H₂enMe)₄{Cu^ICu^II[Mo^V ₆O₁₂(OH)₃(PO₄)(HPO₄)₂(H₂PO₄)]₂}?·?3H₂O (2), were hydrothermally synthesized and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction analysis. Crystallographic analysis reveals that 1 is constructed from cluster anions {Cu^I[Mo^V ₆O₁₂(OH)₃(HPO₄)(PO₄)₃]₂}^15?, protonated organic amines, and water molecules. Each cluster is bridged through hydrogen bonds to form a 3-D supermolecular structure. For 2, {Cu^I[Mo^V ₆O₁₂(OH)₃(PO₄)(HPO₄)₂(H₂PO₄)]₂}^11? are connected by Cu^II cations to form an infinite chain. The formation of 1 and 2 reveals that organoamines influence the structures of the crystals.     

Keplerate巨型纳米多孔聚氧钼酸盐作为可重复使用催化剂用于合成1,2,4,5-四取代咪唑(英文)

The Keplerate‐type giant nanoporous isopolyoxomolybdate (NH4)42[MoVI72MoV60O372‐(CH3COO)30(H2O)72], denoted {Mo132}, has been used as a catalyst for the synthesis of1,2,4,5‐tetrasubstituted imidazoles by the one‐pot, four‐component thermal reaction of benzil with aromatic aldehydes, primary amines, and ammonium acetate under solvent‐free conditions. The catalyst was prepared according to a previously published literature procedure using inexpensive and readily available starting materials, and subsequently characterized by FT‐IR, UV and X‐ray diffraction spectroscopy, as well as microanalysis. The results showed that {Mo132} exhibited high catalytic activity towards the synthesis of 1,2,4,5‐tetrasubstituted imidazoles, with the desired products being formed in good to high yields. Furthermore, the catalyst was recyclable and could be reused at least three times without any discernible loss in its catalytic activity. Overall, this new catalytic method for the synthesis of 1,2,4,5‐tetrasubstituted imidazoles provides rapid access to the desired compounds following a simple work‐up procedure, and avoids the use of harmful organic solvents. This method therefore represents a significant improvement over the methods currently available for the synthesis of tetrasubstituted imidazoles.