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In the work, by incorporating polyoxometalates (POMs) into a copper(II)-based network, a novel three-dimensional (3D) porous framework, [Cu

Fourteen lanthanide (Ln)-containing hetero selenato-phosphato-peroxopolyoxoniobates in three series: (1) Cs

Three Ru-induced structural interconversion polyoxometalates (POMs), Na

Two isostructural valence tautomeric (VT) complexes with different critical temperatures were prepared and fully investigated through a series of magnetic, structural, spectral, and differential scanning calorimetry evidence. The kinetic effect in the VT complex was observed for the first time through scan-rate-dependent studies and further validated by annealing tests.

A novel binuclear ruthenium-based polyoxometalate, K

The crown-shaped organotriphosphonate-modified 36-molybdenum cluster (NH4)18Na7H11[Zn(H2O)TeMo6O21{N(CH2PO3)3}]6·23H2O (1) has been synthesized, which is the largest zinc-containing organophosphonate-based polyoxometalate to date. Compound 1 was prepared in buffer solution (pH 5.5) with heptamolybdate and amino trimethylene phosphonic acid (ATMP) as the organic ligand. The polyanion constructed from a hexmeric assembly of [Zn(H2O){TeMo6O21}{N(CH2PO3)3}]6- subunits has been fully investigated by a few characterization methods. In this work, we discovered that 1 exhibited reversible photochromism and it changed from white to reddish brown upon UV irradiation. In addition, compound 1, as a catalyst, can oxidize sulfides to sulfoxides, showing a high yield/conversion and a good selectivity.

A dl-alanine covalently bonded giant arsenotungstate, namely, Na

Polyoxometalate (POM) anions were successfully integrated into Fe(II) spin crossover (SCO) system, which demonstrates an effective role in regulating spin-state switching properties. Specifically, three drastically different magnetic behaviors of Fe(II) ion in the identical cation [Fe(bpp)

A novel telluroniobate, K

A novel organodiphosphonate-based telluromolybdate cluster, (NH4)6Na3H13[TeMo10O37(CoMo2O6L)4]·11H2O [1; L = (O3P)2C(O)(CH2)3NH2], has been successfully synthesized by a simple one-pot aqueous reac...

Developing new catalysts for highly efficient and selective oxidation of saturated C-H bonds is significant due to their thermodynamic strength. Via incorporation of PW12O403-, pyridine-2,5-dicarboxylic acids (pydc), and Fe(III) ions into one framework, a new polyoxometalate-based metal-organic framework, [HFe4O2(H2O)4(pydc)3PW12O40]·10.5H2O (FeW-PYDC), was successfully prepared by a hydrothermal method. Interestingly, FeW-PYDC features a three-dimensional porous structure with {Fe4O2} interconnecting with PW12O403- units. FeW-PYDC displayed excellent performance in the selective oxidation of C-H bonds of alkylbenzenes with high conversion (95.7%) and selectivity (96.6%). As an effective heterogeneous catalyst, FeW-PYDC demonstrates good reusability and structural stability.

A series of benzoate-decorated lanthanide (Ln)-containing tetrameric Dawson-type phosphotungstates [N(CH3)4]6H20[{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]2Cl2·98H2O [Ln = Sm (1), Eu (2), and Gd (3)] were made using a facile one-step assembly strategy and characterized by several techniques. Notably, the Ln-containing tetrameric Dawson-type polyoxoanions [{(P2W17O61)Ln(H2O)3Ln(C6H5COO)(H2O)6]}{[(P2W17O61)Ln(H2O)3}]224- are all established by four monolacunary Dawson-type [P2W17O61]10- segments, encapsulating a Ln3+ ion with two benzoates coordinating to the Ln3+ ions. 1-3 exhibit reversible photochromism, which can change from intrinsic white to blue for 6 min upon UV irradiation, and their colors gradually recover for 30 h in the dark. The solid-state photoluminescence spectra of 1 and 2 display characteristic emissions of Ln components based on 4f-4f transitions. Time-resolved emission spectra of 1 and 2 were also measured to authenticate the energy transfer from the phosphotungstate and organic chromophores to Eu3+. In particular, 1 shows an effectively switchable luminescence behavior induced by its fast photochromism.

Two multi-Rh-incorporated polyoxometalates [NH

In view of the water pollution issues caused by pathogenic microorganisms and harmful organic contaminants, nontoxic, environmentally friendly, and efficient antimicrobial agents are urgently required. Herein, a nickel-based Keggin polyoxomolybdate [Ni(L)(HL)]2H[PMo12O40] 4H2O (1, HL = 2-acetylpyrazine thiosemicarbazone) was prepared via a facile hydrothermal method and successfully characterized. Compound 1 exhibited high stability in a wide range of pH values from 4 to 10. 1 demonstrated significant antibacterial activity, with minimum inhibitory concentration (MIC) values in the range of 0.0019–0.2400 µg/mL against four types of bacteria, including Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Escherichia coli (E. coli), and Agrobacterium tumefaciens (A. tumefaciens). Further time-kill studies indicated that 1 killed almost all (99.9%) of E. coli and S. aureus. Meanwhile, the possible antibacterial mechanism was explored, and the results indicate that the antibacterial properties of 1 originate from the synergistic effect between [Ni(L)(HL)]+ and [PMo12O40]3−. In addition, 1 presented effective adsorption of basic fuchsin (BF) dyes. The kinetic data fitted a pseudo-second-order kinetic model well, and the maximum adsorption efficiency for the BF dyes (29.81 mg/g) was determined by the data fit of the Freundlich isotherm model. The results show that BF adsorption was dominated by both chemical adsorption and multilayer adsorption. This work provides evidence that 1 has potential to effectively remove dyes and pathogenic bacteria from wastewater.

By integration of {Ln(H

A new family of trinuclear transition-metal (TM)-sandwiched heteropolyoxovanadates (hetero-POVs) [(SeV10O28(SeO3)3M(H2O)3)2(M(H2O)4)]10- (Se8V20M3, where M = Mn2+, Co2+, and Zn2+) were prepared using two feasible approaches: a stepwise assembly strategy atop the POV precursor Se4V10 and a one-pot reaction approach of KVO3, SeO2, TM2+, and a proline ligand. The crystallographic studies reveal that Se8V20M3 consist of two asymmetric [SeV10O28(SeO3)3M(H2O)3)]6- units, linked by another TM2+ ion, thus forming an interesting staggered sandwich-type arrangement. Additionally, Se8V20M3 and Se8V20M present strong correlations between their structures and catalytic properties. In particular, Se8V20M3 demonstrate an analogical heterogeneous catalytic performance as Se8V20M in the sulfoxidation reaction of thioethers owing to their structural similarities.

Two DyIII complexes, [Dy(bbpen-F)X] [X = Cl (1), Br (2); H2bbpen-F = N,N'-bis(2-hydroxybenzyl)-N,N'-bis(5-fluoro-2-methylpyridyl)ethylenediamine], have been synthesized that show remarkable single-molecule-magnet behavior with effective barriers of magnetic reversal of 837.7 K for 1 and 1149.7 K for 2 under zero direct-current field and hysteresis loops up to 20 K for 1 and 30 K for 2, as confirmed by magnetic properties and ab initio calculations.

A high-nuclearity nickel-substituted polyoxotungstate, Na6K5.5H4.5 {[Ni8(OH)6(H2O)2](CO3)3(SiW9O34)2}·22H2O (1), has been obtained by the reaction of Na10[α-SiW9O34]·18H2O, Ni(NO3)2·6H2O and K2CO3 in aqueous solution and characterized by IR spectroscopy, single crystal X-ray diffraction, thermal gravimetric analysis and elemental analysis. Carbonate is not only used to adjust the pH of the solution, but also is a structure-stabilizing agent. The polyoxoanion {[Ni8(OH)6(H2O)2](CO3)3(SiW9O34)2}16- (1a) can be regarded as two {[Ni4(OH)3(H2O)](SiW9O34)} subunits connected by three carbonate groups, which represents the first polyanion containing an octanuclear nickel cluster based on trivacant Keggin-type polyoxotungstate {XW9} (X = heteroatom). The subunit {[Ni4(OH)3(H2O)](SiW9O34)} can be viewed as a tetranuclear nickel cluster linked to a trivacant Keggin-type polyoxotungstate {SiW9O34}. Furthermore, magnetic measurements show that 1 exhibits antiferromagnetic interactions.

A new organic–inorganic hybrid heteropolyoxoniobate, [{Cu(en)(H2O)4}{Cu(en)2(H2O)}{Cu(en)2(H2O)2}]1.5[H8SiTe8Nb15O64]·6H2O (1; en = ethanediamine), has been successfully synthesized by a convention...

We report the synthesis, characterization, and solution self-assembly of plenary Nb6P2W12-based transition-metal substituted polyoxometalate, which is obtained by simply adding transition metals (C...

The oxidation of silanes into silanols is a very necessary transformation, and yet the rational fabrication of efficient catalysts for this reaction remains a challenging task. Here, a 3D polyoxometalate-based metal-organic framework (POMOF), [Cu

Amyloid β-peptide (Aβ) misfolding aggregates with β-sheet structures and surplus reactive oxygen species (ROS) are both considered to be the culprit of neuronal toxicity in Alzheimer’s disease (AD). Therefore, modulating the misfolding mode of Aβ and inhibiting ROS simultaneous has become an important method for anti-AD. Herein, a nanoscale manganese-substituted polyphosphomolybdate (H2en)3[Mn(H2O)4][Mn(H2O)3]2[P2Mo5O23]2·14.5H2O (abbreviated as MnPM) (en = ethanediamine) was designed and synthesized by single crystal to single crystal transformation method. MnPM can modulate the β-sheet rich conformation of Aβ aggregates, and thus reduce the formation of toxic species. Moreover, MnPM also possesses the ability to eliminate the free radicals produced by Cu2+-Aβ aggregates. It can inhibit the cytotoxicity of β-sheet-rich species and protect synapses of PC12 cells. MnPM combines the conformation modulating ability of Aβ and anti-oxidation ability, which makes a promising multi-funcational molecular with a composite mechanism for the new conceptual designing in treatment of such protein-misfolding diseases.

A novel polyoxoniobate cluster directed by AsO33–, {[Cu(phen)]5[Nb6O19][As2Nb6O22]}2 (1a), has been successfully synthesized by a “two-pot” strategy, namely, the conventional aqueous solution and d...

Polyoxotungstate supported titanocene {Cp2Ti}2+ clusters H6{K8(Cp2Ti)2P4W24O88(PO4)2}·14H2O (1), H6[Na2P4W14O58(Cp2Ti)2]·12H2O (2), and H2[K6{Cp2Ti}{PW9O33(WO2)}2{NC5H3(COOK)2}(NC5H3(CH3)COOK)·22H2O] (3) have been synthesized, and their single crystal X-ray structures have revealed unprecedented and intriguing structural features. The synthesized compounds have been characterized by various spectroscopic techniques including UV–vis, cyclic voltammogram, NMR, ESI-MS, and inductive coupled plasma spectroscopy (ICP) in solution and also by IR, TGA, and diffuse reflectance in the solid state. Clusters 1 and 2 are rare examples of lacunary POM supported titanocene clusters obtained by incorporating various phosphorus heteroatoms to form elusive phosphotungstate assemblies, whereas 3 is an unprecedented organometallic as well as heteroleptic pyridyl functionalized POM. Clusters 1–3 show transient photocurrent ON/OFF behavior upon UV-light irradiation and also exhibit characteristic TiIV/III intravalence electro...

As a new field in POM-based functional materials, polyoxometalate-based coordination polymers (POMCPs), especially transition-metal-containing POMCPs (TM-POMCPs), have undergone substantial advancements over the past few decades for their impressive structural features and desirable properties in optics, electrochemistry, and organic catalysis. Notably, TM-POMCPs based on Keggin-type POM building blocks have attracted widespread research interest and account for more than half of the compounds reported in this class. Keggin-type POMs, strong Lewis acids with adjustable redox properties, can interact with transition metals via self-assembly in the presence of organic ligands, combining the advantages of the three constituents and resulting in many improved properties. This review focuses on Keggin-type TM-POMCPs, which are extended structures with covalently bound metal-oxide clusters with 1D chains, 2D layers, and 3D frameworks. Such coordination polymers not only enrich the structural diversity of Keggin-type POM derivatives but also provide a suitable pathway for designing functional materials with outstanding properties directed by structure–property relationship. In this review, we highlight and discuss the structural features of Keggin-type TM-POMCPs based on various dimensionalities. Furthermore, synthetic strategies and relevant applications, especially in the field of catalysis, are overviewed.

A novel organic-inorganic hybrid dimeric tungstoantimonate [Cu(H2O)4]{[Cu(bpy)] [Cu3(bpy)3(H2O)](SbW9O33)}2·15H2O (1) (bpy = 2, 2′-bipyridine) was synthesized by the metastable precursor [NaSb9W21O86]18−, which was further characterized by IR spectrum, thermogravimetric analysis (TGA), and X-ray single-crystal diffraction. Structural analysis revealed that 1 consists of the two trivacant organo-functionalized {[Cu(bpy)][Cu3(bpy)3(H2O)](SbW9O33)}− units linked together by one [Cu(H2O)4]2+ group resulting in a dimeric architecture. Magnetic property studies indicate that obvious antiferromagnetic interactions above 25 K and weak ferromagnetic coupling interactions below 25 K in these paramagnetic Cu(II) ions.

Two novel polynuclear dysprosium (Dy)-containing polytungstoarsenates, CsK7Na16[(AsW9O33)6Dy6W10O24(H2O)23]·40H2O (1) and Cs2K18Na18[(AsW9O33)7Dy7W8O21(H2O)17(μ3-OH)(OH)]·78H2O (2), have been synthesized via the reaction of the preformed polyoxometalate (POM) precursor [As2W19O67(H2O)]14- and Dy3+ ions through controlling pH. The polyanion of 1 can be described as a dimer of two similar trimers {(AsW9O33)3Dy2W5O12(H2O)6} that are linked by Dy cation and two μ2-oxo groups, and the Dy(III) ions in 1 are arranged in a linear fashion. Compound 2 presenting an interesting W-shaped structure, assembly composed of a dimeric {(AsW9O33)2W3Dy2O8(H2O)7}, a trimer {(AsW9O33)3W4Dy2O11(OH)(H2O)3}, and a particular sandwiched {(AsW9O33)2WDy3O4(μ3-OH)(H2O)7} segment concatenated by μ2-oxo groups. The solid-state luminescence performances and lifetime decay behaviors of 1 and 2 were systematically researched at ambient temperature, and time-resolved fluorescence spectra of 1 and 2 indicate energy transfer (ET) from the photoexcitation O → M ligand to the metal charge-transfer (LMCT) bands of the POM ligands to Dy3+ ions. Moreover, the dynamic magnetic measurement indicates that 1 and 2 exhibit slow relaxation of the magnetization.

A copper-containing polyoxometalate-based metal-organic framework (POMOF), CuI12Cl2(trz)8[HPW12O40] (HENU-7, HENU = Henan University; trz = 1,2,4-triazole), has been successfully synthesized and well-characterized. In addition, the excellent catalytic ability of HENU-7 has been proved by the selective oxidation of diphenylmethane. Under the optimal conditions, the diphenylmethane conversion obtained over HENU-7 is 96%, while the selectivity to benzophenone is 99%, which outperforms most noble-metal-free POM-based catalysts. Moreover, HENU-7 is stable to reuse for five runs without an obvious loss in activity and also can catalyze the oxidation of different benzylic C-H with satisfactory conversions and selectivities, which implied the significant catalytic activity and recyclability.

Two-dimensional (2D) crystalline porous materials with designable structures and high surface areas are currently a hot research topic in the field of proton- and electron-conducting materials, which provide great opportunities to orderly accommodate carriers in available spaces and to accurately understand the conducting path. The 2D dual-conductive inorganic framework [Co(H2O)6]2{[Co(H2O)4]4[WZn3(H2O)2(ZnW9O34)2]}·8H2O (Co6Zn5W19) is synthesized by combining [WZn3(H2O)2(ZnW9O34)2]12- (Zn5W19) and a Co(II) ion via a hydrothermal method. Due to the presence of a consecutive H-bonding network, electrostatic interactions, and packing effects between the framework and guest molecules, Co6Zn5W19 displays a high proton conductivity (3.55 × 10-4 S cm-1 under 98% RH and 358 K) by a synergistic effect of the combined components. Additionally, a photoactuated electron injection into the semiconducting materials is an important strategy for switching electronic conductivity, because it can efficiently reduce the frameworks without destroying the crystallinity. I-V curves of a tablet of Co6Zn5W19 in the reduced and oxidized states yield conductivities of 1.26 × 10-6 and 5 × 10-8 S cm-1, respectively. Moreover, Co6Zn5W19 is also successfully applied in the photocatalytic reduction of the toxic Cr(VI) metal ion by utilizing its excellent electronic storage capacity and Baeyer-Villiger (BV) oxidation in a molecular oxygen/aldehyde system.

A novel crown-shaped 36-molybdate cluster with organophosphonate-functionalized polyoxomolybdates, (NH4)17Na7H12[Co(H2O)TeMo6O21{N(CH2PO3)3}]6·42H2O, has been successfully synthesized and well-characterized. It owns the highest nuclearity in the family of organophosphonate-based polyoxometalates reported so far. Furthermore, for the first time in the field, we illustrated that polyoxomolybdate could work as an effective heterogeneous catalyst for the Knoevenagel condensation reaction with high TOF (7714 h-1) and good recyclability. Impressively, the catalytic performance of 1 was also tested successfully in a large scale (∼10 g) reaction, where 89% of reaction yield and 3216 of TON were afforded.

POM-supported metal carbonyl derivatives (PMCDs) represent a family of tremendous potential catalysts owing to their peculiar physical and chemical properties. Yet low-valence transition metal-substituted Dawson-type PMCD catalysts are uncommon. Hence, we synthesized a tricobalt-substituted PMCDs by conventional aqueous solution method, [Na(H2O)5](NH4)7[P2W15O56Co3(H2O)3(OH)3Re(CO)3]·13H2O (1), and characterized by single crystal X-ray diffraction crystallography, IR, and thermogravimetric analyses (TGA), etc. The obtained compound 1 was employed as a catalyst for the oxidation of diphenylmethane (DPM) to benzophenone, giving 96.8% yield in the presence of tert-butyl hydroperoxide (TBHP) and pyridine. The control experiments indicate that Co metal ion plays an important role in the catalytic reactions. As a side note, the electrospray ionization mass spectrometry (ESI-MS) and UV spectroscopy showed that 1 can retain its integrity in solution, and magnetic measurements indicated that 1 exhibited a weaker ferromagnetic interaction at low temperature.

Two neutral polyoxotantalates {[CuL]2[Cu(L)2]2[Ta6O19]}·nH2O have been synthesized by conventional reaction conditions, and characterized via different physical methods. Single-crystal X-ray analyses were carried out on {[CuL]2[CuL2]2[Ta6O19]}‧21H2O (L = 1,10-phen, denoted as 1) and the isostructural {[CuL]2[CuL2]2[Ta6O19]}‧20H2O (L′ = 2,2′-bipy, denoted as 2). Both complexes comprise a Lindqvist [Ta6O19]8− hexatantalate which acts as an octadentate ligand to coordinate two [CuL] units and two [CuL2] fragments through six bridging and two terminal oxygen atoms. In addition, the solid-state magnetic susceptibility of 1 and 2 are investigated briefly.

Polyoxometalates (POMs) have demonstrated strong potential in various fields, such as catalysis, magnetism, medicine, photochemistry and materials science, for their remarkable physical and chemical properties. Through the introduction of organic functional moieties to the POM systems via self-assembly, grafting, doping or intercalation strategies, advantages from both the POMs and organic moieties are well maintained, resulting in many new properties. Among all the existing organo-functionalized POMs, carboxylate covalently modified POMs (CCMPs, carboxylic acid ligands covalently grafted to the POM skeletons) attract intensive research efforts. The carboxylic acid ligands not only help to enrich the structural diversities of the CCMPs, but also facilitate the tuning of redox behaviors and photoreduction activities of the CCMPs because of the possible electron transfer between the organic ligands and the POM units. Encouraged by the impressive structural diversities and potential applications in optics, magnetism and materials science, the design and exploration of new CCMP complexes have become some of the most compelling and challenging areas in POM chemistry. In this review, we herein discuss the research progress achieved for CCMPs in the past decades in the areas of synthesis methodologies, structural features and relevant applications (photochromism, photoluminescence and magnetism, etc.). In addition, some personal insights are also presented in the last section of the paper with sincere wishes for continuous exploration of the undiscovered world of CCMPs.

By adopting different crystal growth methods, two novel organic-inorganic hybrids, [{Cu(phen)}6(H2O)(Te5Nb15.5Cu0.5O57)]3.5- and its dimer, have been successfully synthesized. These are fabricated by simple compound reactions and directed by the tellurite anions, which act as heteroanion templates and linkers, as well as a pendant ligand. The compounds were characterized by IR spectra, UV/vis, thermogravimetric analysis, and single crystal X-ray diffraction. Furthermore, the solution behavior was also investigated.

A novel polyoxometalate cluster, i.e., Na1.5H4.5[(CH3)4N]2{[Mn(CO)3]4(Se2W11O43)}·9H2O (1), has been successfully synthesized under moderately acidic conditions. Compound 1 contains four electron-donating {Mn(CO)3}+ organometallic entities, which are grafted over an unprecedented heteropolytungstate electron-acceptor group. Compound 1 was further structurally characterized by various physicochemical techniques like elemental analyses, inductively coupled plasma (ICP) analyses, IR and UV–vis spectroscopy, electrochemistry, and single-crystal X-ray diffraction, and so on. The polyoxoanion of 1 comprises a novel {Se2W11} fragment, which is obtained from molecular assembly of rare {SeW3} and {SeW8} species. Evaluation of the data from solution-state IR spectrum showed excellent agreement with the solid state IR spectrum, indicating the intact clusters in the CH3CN/Na2SO4 solvent. Also, negative electrospray ionization mass spectrometry (ESI-MS) was an alternative tool to verify the stability of 1 in the mixed...

The first Co-containing polyoxotantalate cluster, [H5Co8Ta24O80]15–, has been obtained. The tetramer has by far the highest degree of polymerization of any polyoxotantalate based on {Ta6O19} and is the largest high-nuclearity Co-cluster-containing polyoxotantalate obtained thus far. The synthesis of new polyoxotantalates has long been a challenging subject in polyoxotantalate chemistry. The findings of this study show the possibility of using Ta-based polyoxometalates as ligands to construct large aggregated structures analogous to the related Nb compounds. Therefore, the work demonstrates exciting progress in the synthesis of new polyoxotantalates.

A new [P2W16O59]12− ({P2W16})-based polyoxometalate (POM) derivative (TMA)10H5[Ce3(H2O)6(P2W16O59)2]⋅41H2O (1) (TMA = tetramethyleneamine) was successfully synthesized, which has been characterized by single crystal X-ray diffraction analysis, elemental analyses, cyclic voltammetry, thermogravimetric analyses (TGA), IR spectroscopy and 31P NMR spectroscopy. The single crystal X-ray diffraction analyses indicate that polyanion of 1 consists of two divacant {P2W16} units connected by one standard isosceles triangle {Ce3} bridging cluster via Ce O W and Ce O P linkages. The investigation of 31P NMR spectroscopy shows the presence of two types of phosphorus in compound 1. The study of magnetic susceptibility for 1 reveals the strong spin-orbital coupling and weak antiferromagnetic interactions exist in the three Ce3+ ions. The photoluminescence study indicates that the presence of 5d → 4f electron transition of Ce3+ ion in 1.

A series of DyxEr(1–x)-polyoxometalates (POMs) were successfully synthesized and characterized well by various physicochemical analysis. The structurally isolated compounds exhibit three characteristic emissions at 480 nm (blue, 4F9/2 → 6H15/2 transition), 573 nm (yellow, 4F9/2 → 6H13/2 transition), and 663 nm (red, 4F9/2 → 6H11/2 transition) whose luminescent color coordinates appear in the near-white area in the CIE 1931 chromaticity diagram. Time-resolved emission spectroscopy was used in DyxEr(1–x)-POM to further authenticate energy transfer from the photoexcitation O → M ligand to the metal charge-transfer state of phosphotungstate components to active Dy3+/Er3+ ions and energy transfer between Dy3+ ion and Er3+ ion via intramolecular energy transitions. The relative emission intensity of ∼32%, ∼53%, and ∼85% for Dy-POM, Dy0.9Er0.1-POM, and Dy0.8Er0.2-POM respectively, were obtained under 300 min of UV irradiation, which indicates better photostability of Dy0.8Er0.2-POM. Furthermore, DyxEr(1–x)-POM s...

Oxidation of organosilanes is one of the pivotal reactions in organic synthesis and the corresponding products of silanols are widely as raw materials in industrial processes. In this paper, a new type of polyoxomolybdate containing mixed-valence antimony, [SbVSbIII4Mo18O66]7− (1a), has been isolated as tetramethyl ammonium salt in aqueous solution. The compound was structurally characterized by FT-IR, XPRD, TG, XPS, ESI–MS etc. It is the first time that the containing mixed-valence antimony polyoxomolybdate was used as a heterogeneous catalyst to efficaciously catalyze the oxidation of organosilanes to silanols under mild reaction conditions. Furthermore, the catalyst was stable and maintained its catalytic activity after three reaction cycles.

A novel class of organophosphonate-based polyoxomolybdate derivatives, K4H5[Ln3(H2O)14{(Mo8O24)(O3PCH2COO)3}2]·23H2O (Ln = Gd (1Gd), Tb (2Tb), Dy (3Dy)), have been fully investigated by a few characterization methods such as single-crystal X-ray crystallography, XRPD, elemental analysis, TGA, and IR spectra. The magnetic properties of 1Gd, 2Tb, and 3Dy were investigated, as well as the solid-state luminescence properties of 2Tb and 3Dy. The catalysis properties of 1Gd, 2Tb, and 3Dy for thioether oxidization have been investigated using hydrogen peroxide (H2O2) as an oxidant. The catalysis study demonstrated the efficient and selective conversion of various thioethers to their corresponding sulfones in excellent yields.

The high-nuclearity polyoxovanadate-based carboxylate derivative K6H[VV17VIV12(OH)4O60(OOC(CH2)4COO)8]·nH2O (1) has been successfully synthesized by conventional aqueous methods and structurally characterized. The [VV17VIV12(OH)4O60(OOC(CH2)4COO)8]7- polyanion is built up from three cages: one {VV17(OH)4O44} cage and two identical [(VIV3O6)2(OOC(CH2)4COO)4]8- cages. Of the three cages, the {VV17(OH)4O44} is a purely inorganic polyoxovanadate cluster, whereas each of the [(VIV3O6)2(OOC(CH2)4COO)4]8- cages is a vanadium-based organic-inorganic hybrid cluster framed via four adipate ligands linking simultaneously to two triangular {V3} units. The two [(VIV3O6)2(OOC(CH2)4COO)4]8- cages are covalently attached to the central {VV17(OH)4O44} cage via V-O-V bonds in a linear arrangement, resulting in a {V29}-based hybrid cluster skeleton. The catalytic properties of compound 1 for the oxidation of sulfides by tert-butyl hydroperoxide were investigated, and the result indicates that 1 exhibits excellent catalytic activity for the oxidation of sulfides under mild conditions.