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A water‐soluble copper catalyst (NH4)8[Cu2(H2O)8W12O42] ⋅ 4H2O is prepared by the generated paratunngstate B in situ, which can catalyze the H2O2 oxidation of cyclohexanol to cyclohexanone with a yield above 98 % in water under much milder conditions of 35 °C and atmospheric pressure, and the substrate can be extend to other secondary alcohols, potentially leading to an economical, green, and efficient ketone production method for industrial use. [ABSTRACT FROM AUTHOR]

Novel Anderson-type polyoxomanganotungstate clusters with the β-isomer structure, [{R1R2C(CH2O)2}MnIVW6O22]6−, were synthesized and monofunctionalized with derivatives of 1,3-propanediol via a one-pot strategy, and show unprecedented coordination activity as non-lacunary polyoxotungstate clusters and could have potential in the future construction of POM-frameworks. [ABSTRACT FROM AUTHOR]

Several novel triol-ligands functionalized Anderson–Evans type polyoxotungstates, K3Na3[{HOCH2C(CH2O)3}AlO3W6O18], K3Na3[{HOCH2C(CH2O)3}CrO3W6O18], K3Na3[{HOCH2C(CH2O)3}CoO3W6O18], and K3Na3[{H3CC(CH2O)3}CoO3W6O18], were successfully synthesized and characterized, in which some of the central metal ions have never been found in the Anderson-type polyoxotungstates. The single crystal X-ray diffraction analysis indicated that the clusters were on a status, in which only one-side μ3-O was protonated. This indicates that the three-protonated cluster is a common type of Anderson cluster aside zero-protonated (A-type) and six-protonated (B-type), which could be named as the T-type. [ABSTRACT FROM AUTHOR]

A series of metallic silver and graphene (GR) co-doped monoclinic BiVO 4 ternary systems (Ag/GR/BiVO 4 ) are demonstrated by a single-step solvothermal method. The phase and chemical structure, morphology, textural and optical absorption properties of the Ag/GR/BiVO 4 ternary systems are well characterized, and then their simulated sunlight and visible-light photocatalytic activity were evaluated by the degradation of a typical dye pollutant, rhodamine B (RhB). For comparison, binary systems of Ag/BiVO 4 and GR/BiVO 4 as well as solitary BiVO 4 are also tested under the same conditions. Meanwhile, the separation and transportation of the photogenerated carriers in the simulated sunlight-irradiating Ag/GR/BiVO 4 ternary systems are studied by photoelectrochemistry experiments, and the active species generated during the process of photodegradation are investigated by free radical and hole scavenging experiments. On the basis of the above results, mechanism of photocatalytic degradation of RhB over the Ag/GR/BiVO 4 ternary system is revealed. Finally, the reusability of the catalyst was evaluated by five consecutive catalytic runs. [ABSTRACT FROM AUTHOR]

Abstract: Three monofunctionalized organoimido derivatives of [Mo6O19]2− bearing an electron-withdrawing chloro group (R= p-ClC6H4 1, m-ClC6H4 2, or o-ClC6H4 3) have been prepared in high purity and moderate to good yields using an easy reaction route of [α-Mo8O26]4− with corresponding aromatic amine hydrochlorides or a mixture of aromatic amines and their hydrochloride salts in the presence of N,N′-dicyclohexylcarbodiimide (DCC). These complexes have been characterized by 1H NMR, IR, UV–Vis, UV–Vis-NIR reflectance spectroscopy, cyclic voltammetry, and their semiconductive and redox properties were explored by these techniques. Their electronic absorption spectra were also interpreted based on first-principles electronic structure calculations and these features of the simulated spectra are qualitatively consistent with the observed UV spectra. Additionally, the composition and structure of compounds 1 and 2 were further confirmed by X-ray single-crystal diffraction studies. [Copyright &y& Elsevier]

A hydrothermal reaction of WO3, CoCl2 and 4,4′-bipyridine, yields a novel organic–inorganic hybrid compound, Co2(bpy)6(W6O19)2, at 170°C. X-ray single crystal structure determination reveals a two-dimensional covalent structure belonging to monoclinic crystal system, space group C2/c, with cell parameters a=19.971(4) Å, b=11.523(2) Å, c=16.138(3) Å, β=96.49(3)°, V=3690.0 Å3 and Z=2. The hexatungstate, [W6O19]2-, acts as a building block in bidentate fashion to bridge the Co(II) centers in the crystal structure. The title compound is found to have an optical energy gap of 2.2 eV from UV–Vis–NIR reflectance spectra. [Copyright &y& Elsevier]

A novel organic–inorganic hybrid vanadium arsenate [H3V3O26(AsO4)4(phen)8(H2O)2] · 2H2O 1 (phen=phenanthroline) was synthesized by the hydrothermal reaction of V2O5, VOSO4, Na2HAsO4 · 7H2O, phen and water. Its structure was determined by elemental analyses, XPS spectra, EPR spectrum, TG analysis, IR spectrum and single-crystal X-ray diffraction. [Copyright &y& Elsevier]

Two novel rare earth-substituted tungstoantimonates [H2N(CH3)2]8Na12[Dy2(H2O)6(tar)(Sb2W21O72)]2·40H2O (DySbW) and [H2N(CH3)2]6Na14[Ho2(H2O)6(tar)(Sb2W21O72)]2·25H2O (HoSbW) (H4tar = tartaric acid) were synthesized. The meso-polyanions are alternately linked by {Na3(H2O)3} clusters and DL-tar ligands to form 1D chains. Notably, HoSbW exhibits excellent catalytic activity and high stability for the synthesis of isoindolinones using EtOH as a green solvent. [ABSTRACT FROM AUTHOR]

Biomass has garnered considerable attention as a globally available, low-cost, and renewable carbon-neutral source in recent decades. The inherent complexity and stability of biomass made the efficient utilization of biomass under mild conditions a daunting challenge. Recently, significant progress has been made in biomass conversion by functionalized polyoxometalates (POMs) catalysts. In this review, the recent advancements in the synthesis of furan derivatives such as 5-hydroxymethylfurfural (HMF), 2-furaldehyde (furfural), 2,5-diformylfuran (DFF), 5-ethoxymethylfurfural (EMF), and other fine chemicals such as formic acid (FA), alkyl levulinates, polyols and organic acids from renewable inedible biomass by using POMs-based catalytic systems were summarized. The future of POMs-catalyzed sustainable chemistry lies in the development of functionalized task-specific POMs as green catalysts, and the rational design of novel reactions that would ultimately pave the pathway for the establishment of green, effective, inexpensive, and sustainable technologies. [Display omitted] • Polyoxometalates-based catalysts offer great prospects in biomass conversion. • Controllable synthesis and structure regulation of polyoxometalates catalysts for biomass conversion are presented. • The excellent performance of polyoxometalates is demonstrated for the synthesis of various fine chemicals from biomass. • The challenge and prospect of biomass conversion over polyoxometalates are discussed. [ABSTRACT FROM AUTHOR]

A novel organic–inorganic hybrid vanadium arsenate [(VO)2(HAsO4)2(phen)2] 1 (phen=phenanthroline) has been hydrothermally synthesized and structurally characterized. The title compound contains an unusual 1D ladder-like {V/As/O} chain with the phen ligand directly coordinated to the vanadium arsenate skeleton. To the best of our knowledge, 1 represents the first example of 1D vanadium arsenate decorated with the directly coordinated organic ligands. [Copyright &y& Elsevier]

A newly prepared nano-organic–inorganic hybrid compound, videlicet [HPDCD]5[BW12O40]·3H2O (HPDCD = hydrolyzed and protonated 2-cyanoguanidine) (1), has been prepared under reflux condition and analyzed by FT-IR and 1H NMR spectroscopies, TG–DT analysis, FE-SEM, cyclic voltammetry, elemental analyses and also single-crystal and powder X-ray diffraction. Hydrogen bonding is the crucial agent in 1 hybrid structure as can be seen from the X-ray data. In this compound, 3D cage-like cavities are constructed by HPDCD counter-ions through hydrogen bonding. Four types of hydrogen bonds in compound 1 lead to the formation of cage-like cavities. [BW12O40]5− clusters are located into compound 1 cage-like cavities. Five types of HPDCD units create cage-like cavities according to which two types of BW12 clusters are placed between the cavities. Moreover, according to powder X-ray diffraction and field emission SEM analyses, the nano-size of 1 cluster has been confirmed. Furthermore, compound 1 has been considered in terms of the electrocatalytic activity and photocatalytic property. [ABSTRACT FROM AUTHOR]

A new organic-inorganic hybrid consisting of Keggin-type polyoxometalate ([BW12O40]5−) and protonated piperazine, namely [H5O2]2[Hpip]2.5[BW12O40]·4H2O (pip = piperazine, C4H10N2) (1), has been created under reflux state and identified through material identification devices like single-crystal crystallography, FT-IR and 1H-NMR spectroscopies, Powder XRD, TG-DT Analysis, Field Emission SEM, elemental-analysis and cyclic voltammetry. Crystallography investigation exhibits that the main factor in the formation of 1 is the numerous number of hydrogen bonding between organic and inorganic species. The arrangement of Hpip groups creates holes in which the [BW12O40]5− clusters fit into the holes. Furthermore, the electrochemical and photochemical attributes of 1 have been considered, and the outcomes present that 1 owns privileged electrocatalytic activity against the reduction of nitrite ions as well as an appropriate photochemical effect on methylene blue (MB) dye depredation. A new organic-inorganic hybrid consisting of Keggin-type polyoxometalate ([BW12O40]5-) and protonated piperazine, namely [H5O2]2[Hpip]2.5[BW12O40]·4H2O (pip = piperazine, C4H10N2) (1), has been created under reflux state. The electrochemical and photochemical attributes of 1 have been considered, and the outcomes present that 1 owns privileged electrocatalytic activity against the reduction of nitrite ions as well as an appropriate photochemical effect on methylene blue (MB) dye depredation. [ABSTRACT FROM AUTHOR]

Developing polyoxometalate‐cyclodextrin cluster‐organic supramolecular framework (POM‐CD‐COSF) still remains challenging due to an extremely difficult task in rationally interconnecting two dissimilar building blocks. Here we report an unprecedented POM‐CD‐COSF crystalline structure produced through the self‐assembly process of a Krebs‐type POM, [Zn2(WO2)2(SbW9O33)2]10−, and two β‐CD units. The as‐prepared POM‐CD‐COSF‐based battery separator can be applied as a lightweight barrier (approximately 0.3 mg cm−2) to mitigate the polysulfide shuttle effect in lithium‐sulfur batteries. The designed Li−S batteries equipped with the POM‐CD‐COSF modified separator exhibit remarkable electrochemical performance, attributed to fast Li+ diffusion through the supramolecular channel of β‐CD, efficient polysulfide‐capture ability by the dynamic host–guest interaction of β‐CD, and improved sulfur redox kinetics by the bidirectional catalysis of POM cluster. This research provides a broad perspective for the development of multifunctional supramolecular POM frameworks and their applications in Li−S batteries. [ABSTRACT FROM AUTHOR]

Developing polyoxometalate‐cyclodextrin cluster‐organic supramolecular framework (POM‐CD‐COSF) still remains challenging due to an extremely difficult task in rationally interconnecting two dissimilar building blocks. Here we report an unprecedented POM‐CD‐COSF crystalline structure produced through the self‐assembly process of a Krebs‐type POM, [Zn2(WO2)2(SbW9O33)2]10−, and two β‐CD units. The as‐prepared POM‐CD‐COSF‐based battery separator can be applied as a lightweight barrier (approximately 0.3 mg cm−2) to mitigate the polysulfide shuttle effect in lithium‐sulfur batteries. The designed Li−S batteries equipped with the POM‐CD‐COSF modified separator exhibit remarkable electrochemical performance, attributed to fast Li+ diffusion through the supramolecular channel of β‐CD, efficient polysulfide‐capture ability by the dynamic host–guest interaction of β‐CD, and improved sulfur redox kinetics by the bidirectional catalysis of POM cluster. This research provides a broad perspective for the development of multifunctional supramolecular POM frameworks and their applications in Li−S batteries. [ABSTRACT FROM AUTHOR]

The synthesis of a new organic-inorganic nano-hybrid material [H 5 O 2 ][pip] 2.5 [SiMoV 2 W 9 O 40 ]. 7H 2 O (pip = Piperazine) (1) , in which piperazine is connected to a mixed-addenda Keggin structure of polyoxometalate by hydrogen bonding interaction, is reported. This nano-hybrid is characterized by single-crystal X-ray diffraction, fourier transform infrared (FT-IR), proton nuclear magnetic resonance ( 1 H NMR), powder X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTA), field emission scanning electron microscopy (FESEM) and cyclic voltammetry (CV). Single crystal X-ray analysis reveals that compound 1 has been assembled by hydrogen bonding among polyoxometalate, piperazine and crystallization water units. In this compound, polyoxometalates are located in the cavities which are created by piperazine groups in the zigzag form. In addition, based on XRD and FESEM analyzes, the nano composition of compound 1 can be verified. Moreover, the electrochemical properties of 1 were perused, which represent that 1 has an appropriate electrocatalytic activity towards reduction of nitrate (NO 2 − ) ion attributed to the metal-center and piperazine units. [ABSTRACT FROM AUTHOR]

Both polyoxometalates (POMs) and organic small molecular catalysts show excellent performance in chemical synthesis. The incorporation of nanoscale POMs and organocatalysts allows the full expression of their respective merits and enables elusive reactions to be achieved in one catalytic system. However, the covalent combination of such two components has been rarely explored. Here, we have successfully designed and synthesized a bifunctional nanomolecular catalyst L -Pro-Mn-Anderson by grafting L -proline onto an Mn-Anderson POM for the first time, and catalytic experiments show that L -Pro-Mn-Anderson can realize the one-pot alcohol oxidation/three-component reaction to synthesize two types of heterocyclic compounds (5-aryl-pyrimido[4,5-b]quinoline-dione derivatives and pyrazolo[3,4-b] pyridine derivatives) in high yields up to 97%. The detailed characterization of the catalyst and the catalytic mechanism has shown that L -Pro-Mn-Anderson exhibits synergistic effects that combine both organic and inorganic catalytic functions, and the covalent linkage improves the overall redox activity of the molecular catalyst. This study opens up a new way for the design and application of covalently combined organic–inorganic molecular catalysts toward de novo organic synthesis. [ABSTRACT FROM AUTHOR]

A novel supramolecular complex Li3Cl[(HPW12O40)(H24C12O6)3(CH3CN)2] {CR-PW12} was confirmed first to apply as a sulfur host in lithium–sulfur batteries. The {CR-PW12}@S cathode exhibits a reversible capacity of 1120 mA h g−1 at 1.0 C and excellent cycle stability. [ABSTRACT FROM AUTHOR]

A Keggin-type polyoxometalate-based crystalline complex, [(SiMo12O40)Cu6(2,2′-bipy)6(Mo6O22)] (complex 1), has been prepared by using a Waugh-type polyoxometalate building block [MnMo9O32]6−, and for the first time, Waugh-type polyoxometalate was converted to a Keggin-type structure under hydrothermal conditions by using a Teflon-lined reactor with glass vials. The synthesized complex was characterized by single-crystal and powder X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, ultraviolet-visible spectroscopy, X-ray photoelectron spectroscopy, and elemental analysis. Structural characterization results show that complex 1 comprises Keggin-type [SiMo12O40]4− anions and [Cu6(2,2′-bipy)6(Mo6O22)]4+ cation moieties composed of isopolymolybdates with 2,2′-bipy-coordinated copper ions, leading to a three-dimensional (3D) supramolecular network. This polyoxometalate assembly exhibits excellent photocatalytic properties and good cyclic stability for the photodegradation of methylene blue (MB) dye. In addition, the experimental results demonstrate that complex 1 also possesses outstanding electrocatalytic activity for nitrite reduction. [ABSTRACT FROM AUTHOR]

An effective synthetic strategy for the amino-containing organic derivative of hexavanadate, TBA2[V6O13{(OCH2)3CNH2}2], is presented. By using this method, the yield is increased extremely and crystals of the intermediate and cation-exchanged products are both obtained and structurally characterized via single-crystal X-ray diffraction, IR and 1H-NMR. [ABSTRACT FROM AUTHOR]

The direct catalytic oxidation of alcohols to carboxylic acids is very appealing, however, economic and environmentally friendly catalytic systems should be further explored from the aspect of less waste production and a convenient procedure. Herein, we display a structurally defined inorganic ligand-supported iron compound, (TBA)3[FeMo6O18(OH)6] (simplified as FeMo6), which could be used as a heterogeneous molecular catalyst in water for this conversion, with oxygen as the terminal oxidant and KCl as an additive. The oxidation of various alcohols (aromatic and aliphatic) could be achieved in almost all cases under mild conditions and provided the corresponding carboxylic acids in high yields, including some active molecular entities and natural molecules with carboxyl structures. Detailed studies showed that chloride ions could combine with the molecular catalyst FeMo6 to form a supramolecular aggregate FeMo6·Cl, which could effectively catalyze the reaction, relying on the synergistic effect of chloride ions and FeMo6. Control experiments, 1H NMR studies and density functional theory (DFT) calculations showed that the oxidation reaction might involve a free radical pathway. [ABSTRACT FROM AUTHOR]

Anderson-type ([XM6O24]n−) polyoxometalates (POMs) are a class of polymetallic-oxygen cluster inorganic compounds with special structures and properties. They have been paid extensive attention by researchers now, due to their chemical modification and designability, which have been widely applied in the fields of materials, catalysis and medicine. In contemporary years, the application of Anderson-type POMs in catalytic organic oxidation reaction has gradually shown great significance for the research of green catalytic process. In this paper, we investigate the application of Anderson-type POMs in organic synthesis reaction, and these works are summarized according to the different structure of POMs. This will provide a new strategy for further investigation of the catalytic application of Anderson-type POMs and the study of green catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • POM-ZnFe 2 O 4 hybrid is reported first time for overall water splitting. • POM-ZnFe 2 O 4 hybrid delivers extraordinary performance for OER and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. Electrocatalysts play an important role to increase the energy conversion efficiency of electrolysis processes. In this study, a heterostructure of zinc iron oxide (ZnFe 2 O 4) and polyoxometalate (POM) nanoplates (POM–ZnFe 2 O 4) was fabricated for the first time by a hydrothermal process. The hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) analysis of POM–ZnFe 2 O 4 furnished low overpotentials of 268 and 356 mV, and 220 and 290 mV to achieve current densities of 20 and 50 mA cm−2, respectively. In addition, an electrolytic cell composed of a POM–ZnFe 2 O 4 cathode and anode required an operating voltage of 1.53 V to deliver a current of 10 mA cm−2. The improved electrochemical performance of POM–ZnFe 2 O 4 compared to commercial and recently reported catalysts is attributed to the high electrocatalytically active surface area, modulation in the electronic and chemical properties and the formation of heterojunction of ZnFe 2 O 4 and POM, which are vital for accelerating HER and OER activity. [ABSTRACT FROM AUTHOR]

Trifluoromethylation of tetraphenlyborate counterions was successfully used to improve the electrochemical stabilities and device performance of cationic iridium(III) complexes. Melioration of the thermal, photoluminescent, electrochemical, and electrophosphorescent characteristics was achieved. Interionic hydrogen bonds were first found between the aromatic hydrogen atoms in the ancillary ligands of cations and the fluorine atoms in the trifluoromethyl groups of the anions. The strong impact of the counterions on the charge transport in the devices was investigated. A compound with two trifluoromethyl groups in the tetraphenlyborate ion shows the highest photoluminescent efficiency, the best electrochemical stability, and the greatest performance in green-blue-emitting devices, with a high current efficiency of 12.4 cd A−1 and an emission peak at λ=480 nm. The efficiencies achieved are the highest reported for OLEDs with ionic complexes emitting in the blue-green region. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel 3D nano-assembly of NiCo 2 S 4 /PANI@PW 12 /rGO hybrid is reported first time. • NiCo 2 S 4 /PANI@PW 12 /rGO hybrid delivers extraordinary performance for LIB and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. Engineering hierarchical nanostructures with enhanced charge storage capacity and electrochemical activity are vital for the advancement of energy devices. Herein, a highly ordered mesoporous three-dimensional (3D) nano-assembly of Nickel Cobalt Sulphide/Polyaniline @Polyoxometalate/Reduced Graphene Oxide (NiCo 2 S 4 /PANI@POM/rGO) is prepared first time via a simple route of oxidative polymerization followed by a hydrothermal method. Morphological analysis of the resulting hybrid reveals the sheet-like structures containing a homogeneous assembly of PANI@POM and NiCo 2 S 4 on the graphene exterior maintaining huge structural integrity, large surface area and electrochemically active centres. The electrochemical analysis of the nanohybrid as the anode of the lithium-ion battery (LIB) has delivered ultra-huge reversible capacity of 735.5 mA h g−1 (0.1 A g−1 after 200 cycles), superb capacity retention (0.161% decay/per cycle at 0.5 A g−1 for 1000 cycles), and significant rate capability (355.6 mA h g−1 at 2 A g−1). The hydrogen evolution reaction (HER) measurement also proves remarkable activity, extremely low overpotential and high durability. The extraordinary performance of the nanohybrid is due to the presence of abundant electroactive centres, high surface area and a large number of ion exchange channels. These outstanding results prove the advantages of a combination of NiCo 2 S 4 , graphene sheets, and PANI@POM in energy devices. [ABSTRACT FROM AUTHOR]

Abstract: The hexamolybdate cluster has been functionalized with fluorine-containing aromatic amine by the DCC (N,N′-dicyclohexylcarbodiimide) dehydrating protocol and two novel mono-functionalized arylimido derivatives of hexamolybdates bearing the electron-withdrawing trifluoromethyl group and trifluoromethoxy group, (Bu4N)2[Mo6O18(≡NAr)] (Ar= o-CF3C6H4) 1 and (Bu4N)2[Mo6O18(≡NAr)] (Ar= p-OCF3C6H4) 2 have been synthesized by improved method. Complete assignments were achieved for the title compounds by elemental analysis, IR, 1H NMR, UV/visible and single-crystal X-ray diffraction analyses. The preliminary herbicidal activity test indicated that they have some herbicidal activities. [Copyright &y& Elsevier]

Abstract: Two lanthanide-decorated polyoxometalates K[Ln2(α-SiW11O39)(H2O)11] (Ln=La, Ce) have been successfully synthesized and characterized with single-crystal X-ray diffraction, IR spectroscopy and thermogravimetric analysis. The two compounds have analogy structures, which consist of one-dimensional chains based on [α-SiW11O39]8− building blocks. The chains are further connected to a two-dimensional layer by potassium ions. The magnetic studies of compound 1 demonstrate a ferromagnetic interaction in 1. [Copyright &y& Elsevier]

A novel organic−inorganic hybrid solid, (n-Bu4N)2[Mo6O17(NAr)2] (Ar = o-CH3OC6H4) 1, has been prepared by refluxing of (n-Bu4N)2[Mo6O19] and appropriate o-anisidine in acetonitrile with N-N'-dicyclohexylcarbodiimide (DCC) as the dehydrating agent. Compound 1 has been characterized by single-crystal X-ray diffraction. Both of the two terminal o-anisidido ligands are linked, respectively, to an Mo atom of the hexamolybdate in a terminal fashion and exhibit an almost linear coordination mode of the Mo⋮N triple bond character. The two o-anisidido aryl rings on the hexamolybdate cluster lie in the cis position, allowing π−π stacking of phenyl ring among the anions. In the crystal, the cluster anions of 1 aggregate into an interesting 1D double chain along the a-axis through π−π stacking and C−H···O hydrogen-bonding interactions. Compared to the hexamolybdate parent, this solid has a smaller optical band gap of 2.25 eV from UV−visible-near-IR reflectance spectroscopy studies. It has also been characterized by 1H NMR, IR, and UV/Vis spectroscopic techniques. The organic−inorganic hybrid (n-Bu4N)2[Mo6O17(NAr)2] (Ar = o-CH3OC6H4) 1 is built from covalently bonded hexamolybdate and two anisidido groups, together with counter tetrabutylammonium cations. It has an interesting 1D aggregate of cluster anions via π−π stacking and C−H···O hydrogen-bonding interactions. UV−visible-near-IR reflectance spectroscopy studies reveal that it behaves as a molecular semiconductor with a photochemical band gap of 2.25 eV. [ABSTRACT FROM AUTHOR]

A new bicapped Keggin heteropolyoxoanion derivative [Co(bpy) 3 ] 2 [V IV O 40 (V IV O) 2 ] [{Co(bpy) 2 (H 2 O)} 2 {V IV O 40 (V IV O) 2 }]  ·  8H 2 O (1) (bpy  =  2,2′-bipyridine), has been hydrothermally synthesized and structurally characterized by elemental analysis, single crystal X-ray diffraction, IR and X-ray photoelectron spectra. Complex 1 consists of two [Co(bpy) 3 ] 2+ cations, an anion of [V IV O 40 (V IV O) 2 ] 4- and a neutral unit [{Co(bpy) 2 (H 2 O)} 2 {V IV O 40 (V IV O) 2 }] in which {V IV O 40 (V IV O) 2 } 4- is coordinated to two Co atoms through its terminal oxygen atoms of the two capping V atoms at opposite sites together with bipyridine and water ligands. The most interesting feature of 1 is that a polyoxoanion and a neutral component coexist in the crystal structure. Hydrogen-bonding contacts are also formed between different polyanions through the lattice water molecules. [ABSTRACT FROM AUTHOR]

Abstract: The tetra-capped Keggin anion-supported Cobalt–Phenanthroline complex [Co2(phen)2(OH)2(H2O)4]0.5[{Co(phen)2(H2O)}2AsMo6 VIMo2 VV8 IVO44]·2H2O (1) and the bicapped Keggin anion-based Nickel–phenanthroline compound [Ni(phen)2H2O]2[AsMo11 VIMoVO40(VIVO2)0.5].2H2O(2), have been hydrothermally synthesized and structurally characterized by elemental analyses, single crystal X-ray diffraction, IR and X-ray photoelectron spectrum. The interesting structural feature of 1 is that there are two types of free complex cation [Co2(phen)2(OH)2(H2O)4]2+ in different orientations in the crystal structure of 1, and these free complex cations coexist in the space between polyoxometalate clusters. The structure of compound 2 is very like compound 1 except that the Keggin unit is bi-capped instead of tetra-capped. Compounds 1 and 2 are examples that Arsenicum-centered vanadomolybdate anion acts as an active building block in the fabrication of polyoxometalates-supported hybrid solids. Then, the magnetic characteristic of 1 is typical of a dominant ferromagnetic interactions in the 6–300K temperature range and a succedent antiferromagnetic interactions in the very low temperature range (2–6K), while the magnetic behavior for 2 is characteristic of a dominant ferromagnetic interactions in the 6–300K temperature range and succedent antiferromagnetic interactions in the very low temperature range (2–6K). [Copyright &y& Elsevier]

Abstract: A bicapped Keggin anion-supported cobalt–phenanthroline complex (1) has been hydrothermally synthesized and structurally characterized by elemental analyses, single crystal X-ray diffraction and IR spectrum. Interestingly, all the polyanions constitute an anionic layer, while all the polycations are linked to form a cationic layer by the hydrogen bonding interactions. The result of magnetic measurement for compound 1 shows a typical antiferromagnetic interactions in the 2–300K temperature range. [Copyright &y& Elsevier]

Abstract: A novel polyoxometalate-based organic–inorganic hybrid compound, [Co(bpy)3]2 [Mo6O19] [β-(H2Mo8O26)]·4H2O (1), have been hydrothermally synthesized and structurally characterized by elemental analysis, single-crystal X-ray diffraction, IR and X-ray photoelectron spectra. Compound 1 represents the first example that racemic complexes coexisting with two kinds of polyoxomolybdate anions in the same crystal architecture, which should be of rare chance that four kinds of complexes crystallizes into a compound. [Copyright &y& Elsevier]

A novel bifunctionalized arylimido derivative of hexamolybdate, (Bu4N)2[Mo6O17(&z.tbnd6;NAr)2]2− (Ar=o-CH3C6H4) 1, in which the two o-tolylimido groups are bounded to hexamolybdate at the cis positions, was synthesized by self-assembled metathesis of α-type octamolybdate ion and o-toluidine with DCC as a dehydration agent. The most interesting characteristic of 1 is that the cluster anions form dimers via the π–π stacking between one of its two phenyl rings, and four such dimers are linked in turn via C–H⋯O hydrogen bonding involving terminal hexamolybdate oxygen atoms into ring-like tetramers in the solid state. [Copyright &y& Elsevier]

The carbon–carbon bond cleavage of 1,2-diols is an important chemical transformation. Although traditional stoichiometric and catalytic oxidation methods have been widely used for this transformation, an efficient and valuable method should be further explored from the views of reusable catalysts, less waste, and convenient procedures. Herein an inorganic-ligand supported iron catalyst (NH4)3[FeMo6O18(OH)6]·7H2O was described as a heterogeneous molecular catalyst in acetic acid for this transformation in which hydrogen peroxide was used as the terminal oxidant. Under the optimized reaction conditions, carbon–carbon bond cleavage of 1,2-diols could be achieved in almost all cases and carboxylic acids or ketones could be afforded with a high conversion rate and high selectivity. Furthermore, the catalytic system was used efficiently to degrade renewable biomass oleic acid. Mechanistic insights based on the observation of the possible intermediates and control experiments are presented. [ABSTRACT FROM AUTHOR]

The advancement of a naturally rich and effective bifunctional substance for hydrogen and oxygen evolution reaction is crucial to enhance hydrogen fuel production efficiency via the electrolysis process. Herein, facile and scalable hydrothermal synthesis of bifunctional electrocatalyst of polyoxometalate anchored zinc cobalt sulfide nanowire on Ni‐foam (NF) for overall water splitting is reported for the first time. The electrochemical analysis of POM@ZnCoS/NF displays significantly low HER and OER overpotentials of 170/337 and 200/300 mV to attain a current density of 10/40 and 20/50 mA cm−2, respectively, demonstrating the notable performance of POM@ZnCoS/NF toward H2 and O2 evolution reaction in alkaline medium. Additionally, the electrolyzer consisting of the POM@ZnCoS/NF anode and cathode shows an appealing potential of 1.56 V to deliver 10 mA cm−2 current density for overall water splitting. The high electrocatalytic activity of the POM@ZnCoS/NF is attributed to modulation of the electronic and chemical properties, increment of the electroactive sites and electrochemically active surface area of the zinc cobalt sulfide nanowires due to the anchorage of polyoxometalate nanoparticles. These results demonstrate the advantage of the polyoxometalate incorporation strategy for the design of cost‐effective and highly competent bifunctional catalysts for complete water splitting. [ABSTRACT FROM AUTHOR]

A highly efficient method to oxidize methylarenes to their corresponding acids with a reusable Cr catalyst was developed. The reaction can be carried out in water with 1 atm oxygen and K2S2O8 as cooxidants, proceeds under green and mild conditions, and is suitable for the oxidation of both electron-deficient and electron-rich methylarenes, including heteroaryl methylarenes, even at the gram level. The excellent result, together with its simplicity of operation and the ability to continuously reuse the catalyst, makes this new methodology environmentally benign and cost-effective. The generality of this methodology gives it the potential for use on an industrial scale. Differing from the accepted oxidation mechanism of toluene, GC-MS studies and DFT calculations have revealed that the key benzyl alcohol intermediate is formed under the synergetic effect of the chromium and molybdenum in the Cr catalyst, which can be further oxidized to afford benzaldehyde and finally benzoic acid. [ABSTRACT FROM AUTHOR]

Organo disulfides represent an abundant class of compounds in chemical biology, pharmaceutical fields, and industry. They are traditionally synthesized by the oxidation of mercaptan in the presence of an organic ligand supported metal catalyst or toxic oxidants under harsh conditions. Here, we disclose a highly-efficient pathway in which disulfide is synthesized by organic boric acid and Na2S2O3 using the catalyst (NH4)3[CrMo6O18(OH)6], demonstrating a high activity and excellent selectivity. Various boric acid derivatives have been successfully transformed into the corresponding disulfides. Mechanistic insights have been furnished based on the observation of intermediate and control experiments. [ABSTRACT FROM AUTHOR]

We report an efficient method for the oxidative dehydrogenation of hydrazines and diarylamines in aqueous ethanol using Anderson-type polyoxomolybdate-based iron(III) as a catalyst and hydrogen peroxide as an oxidant. A series of azo compounds and tetraarylhydrazines were obtained in moderate to excellent yields. The reaction conditions and substrate scopes are complementary or superior to those of more established protocols. In addition, the catalyst shows good stability and reusability in water. The preliminary mechanistic studies suggest that a radical process is involved in the reaction. [ABSTRACT FROM AUTHOR]

Direct Hydroxylation of benzene to phenol with high yield and selectivity has been the goal of phenol industrial production. Photocatalysis can serve as a competitive method to realize the hydroxylation of benzene to phenol owing to its cost‐effective and environmental friendliness, however it is still a forbidding challenge to obtain good yield, high selectivity and high atom availability meanwhile. Here we show a series of supramolecular catalysts based on alkoxohexavanadate anions and quinolinium ions for the photocatalytic hydroxylation of benzene to phenol under UV irradiation. We demonstrate that polyoxoalkoxovanadates can serve as efficient catalysts which can not only stabilize quinolinium radicals but also reuse H2O2 produced by quinolinium ions under light irradiation to obtain excellent synergistic effect, including competitive good yield (50.1 %), high selectivity (>99 %) and high atom availability. [ABSTRACT FROM AUTHOR]

Direct Hydroxylation of benzene to phenol with high yield and selectivity has been the goal of phenol industrial production. Photocatalysis can serve as a competitive method to realize the hydroxylation of benzene to phenol owing to its cost‐effective and environmental friendliness, however it is still a forbidding challenge to obtain good yield, high selectivity and high atom availability meanwhile. Here we show a series of supramolecular catalysts based on alkoxohexavanadate anions and quinolinium ions for the photocatalytic hydroxylation of benzene to phenol under UV irradiation. We demonstrate that polyoxoalkoxovanadates can serve as efficient catalysts which can not only stabilize quinolinium radicals but also reuse H2O2 produced by quinolinium ions under light irradiation to obtain excellent synergistic effect, including competitive good yield (50.1 %), high selectivity (>99 %) and high atom availability. [ABSTRACT FROM AUTHOR]

Phosphorescent quantum yields have been increased by 12 times by choosing bulky boracic anions as counterions for blue-emitting cationic iridium(iii) complexes. [ABSTRACT FROM AUTHOR]

The direct esterification of alcohols with non-noble metal-based catalytic systems faces great challenges. Here, we report a new chrome-based catalyst stabilized by a single pentaerythritol decorated Anderson-type polyoxometalate, [N(C4H9)4]3[CrMo6O18(OH)3C{(OCH2)3CH2OH}], which can realize the efficient transformation from alcohols to esters by H2O2 oxidation in good yields and high selectivity without extra organic ligands. A variety of alcohols with different functionalities including some natural products and pharmaceutical intermediates are tolerated in this system. The chrome-based catalyst can be recycled several times and still keep the original configuration and catalytic activity. We also propose a reasonable catalytic mechanism and prove the potential for industrial applications. [ABSTRACT FROM AUTHOR]

Aromatic azo compounds, which play an important role in pharmaceutical and industrial applications, still face great challenges in synthesis. Herein, we report a molybdenum oxide compound, [N(C4H9)4]2[Mo6O19] (1), catalyzed selective oxidation of anilines with hydrogen peroxide as green oxidant. The oxidation of anilines can be realized in a fully selectively fashion to afford various symmetric/asymmetric azobenzene and azoxybenzene compounds, respectively, by changing additive and solvent, avoiding the use of stoichiometric metal oxidants. Preliminary mechanistic investigations suggest the intermediacy of highly active reactive and elusive Mo imido complexes. [ABSTRACT FROM AUTHOR]

Aromatic azo compounds, which play an important role in pharmaceutical and industrial applications, still face great challenges in synthesis. Herein, we report a molybdenum oxide compound, [N(C4H9)4]2[Mo6O19] (1), catalyzed selective oxidation of anilines with hydrogen peroxide as green oxidant. The oxidation of anilines can be realized in a fully selectively fashion to afford various symmetric/asymmetric azobenzene and azoxybenzene compounds, respectively, by changing additive and solvent, avoiding the use of stoichiometric metal oxidants. Preliminary mechanistic investigations suggest the intermediacy of highly active reactive and elusive Mo imido complexes. [ABSTRACT FROM AUTHOR]

A simple and efficient protocol for the formylation of amines with formic acid, catalyzed by a polyoxometalate-based chromium catalyst, is described. Notably, this method shows excellent activity and chemoselectivity for the formylation of primary amines; diamines have also been successfully employed. Importantly, the chromium catalyst is potentially non-toxic, environmentally benign and safer than the widely used high valence chromium catalysts such as CrO3 and K2Cr2O7. The catalyst can be recycled several times with a negligible impact on activity. Finally, a plausible mechanism is provided based on the observation of intermediate and control experiments. [ABSTRACT FROM AUTHOR]

A new organic-inorganic hybrid consisting of Keggin-type polyoxometalate ([BW 12 O 40 5-) and imidazole, namely [H 5 O 2 [imi] 4 [BW 12 O 40 ·nH 2 O (imi = Imidazole) (1) , has been created under reflux state and identified through material identification devices like single crystal crystallography, FT-IR and 1H NMR spectroscopies, powder XRD, TG-DT Analysis, field emission SEM, elemental-analysis and cyclic voltammetry. Crystallography investigation exhibits that two main factors which are the numerous number of hydrogen bonding between organic and inorganic species and π-π stacking interaction between two adjacent imidazole rings a have crucial role in 1 formation. In addition, three types of imidazole exist in 1 structure in terms of different kind of hydrogen bonding among [BW 12 O 40 5- clusters and imidazole cations. Furthermore, the electrochemical and photochemical attributes of 1 have been considered, and the outcomes present that compound owns privileged electrocatalytic activity against the reduction of nitrite ions as well as an appropriate photochemical effect on methylene blue (MB) dye depredation. Because of the use of catalyst 1 in the form of modified carbon paste electrode (MCPE) to reduce nitrite ions, and of course its ability to recover and reuse repeatedly in the degradation of MB, this catalyst can be classified in green chemistry domain. Image 1 • This compound is a new organic-inorganic nano-hybrid. • Hydrogen bonding and π-π stacking interaction are two main factors in the formation of 1. • Compound 1 exhibits remarkable electrocatalytical activity on the nitrite reduction. • Hybrid 1 shows notable photocatalytical property on the methylene blue degradation. [ABSTRACT FROM AUTHOR]

Abstract: A new monofunctionized arylimido derivative of hexamolybdate, (Bu4N)2[Mo6O18NC6H4N(CH3)2−p], is synthesized by α-octamolybdate and hydrochloride salt of N,N-dimethyl-1,4-dianiline with DCC as a dehydrating agent. The derivative’s crystal data has been obtained and the IR, UV–Vis, 1H NMR spectra and cyclic voltammetry properties have also been studied. [Copyright &y& Elsevier]

Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes. [ABSTRACT FROM AUTHOR]

Two novel polyoxovanadate-iodoBodipy supramolecular assemblies, named as (2I-BDP-C6)2V6 and (2I-BDP-C6)3V10, were first synthesized by the self-assembly of anionic hexavanadate and decavanadate with cationic iodoBodipy for photochemotherapy, respectively. The mechanisms for synergistic photochemotherapy of the anion–cation pairs were determined. In particular, (2I-BDP-C6)3V10 can effectively kill lung cancer cells (HepG2) by synergetic chemotherapy as well as photodynamic therapy. [ABSTRACT FROM AUTHOR]

The first example of an inorganic-ligand supported iron(III) catalysed coupling of formic acid and amines to form formamides is reported. The pure inorganic catalyst (NH4)3[FeMo6O18(OH)6] (1), which consists of a central FeIII single-atomic core supported within a cycle-shaped inorganic ligand consisting of six MoVIO6 octahedra, shows excellent activity and selectivity, and avoids the use of complicated/commercially unavailable organic ligands. Various primary amines and secondary amines have been successfully transformed into the corresponding formamides under mild conditions, and the formylation of primary diamines has also been achieved for the first time. The Fe catalyst 1 can be reused several times without appreciable loss of activity. [ABSTRACT FROM AUTHOR]