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The usage of reactive oxygen species (ROS) is an effective method to treat pollutants in waste water. Chemical synthesis of artificial oxidase for the degradation of dyes is a new and hot research field from inorganic chemistry to printing and dyeing industry. In this paper, an artificial oxidase based on hybrid arsenomolybdate [Zn(en)2(H2O)2]2[(ZnO6)Mo6O18(As3O3)2] (abbreviated as ZAM, en = ethylenediamine), has been synthesized and structurally characterized by elemental analyses, IR spectrum, UV–Vis spectra, scanning electron microscope with energy dispersive X-Ray and single-crystal X-Ray diffraction. Structural analysis reveals that ZAM is an ionic compound, in which the cations are two [Zn(en)2(H2O)2]2+ coordination complexes and the anion is a modified Anderson-type cluster [(ZnO6)Mo6O18(As3O3)2]4−. Notably, ZAM can catalyze the production of ROS in aqueous solution efficiently. Moreover, it can specifically eliminate methylene blue dyes from the solution system by both adsorption and catalytic oxidation.

A novel ruthenium-containing polyoxometalate-based organic–inorganic hybrid, K4Na9H7.4[(AsW9O33)4(WO2)4{Ru3.2(C3H3N2)2}]·42H2O (1), was successfully synthesized by a one-step hydrothermal method under acidic conditions, which applied a self-assembly strategy between inorganic polyoxometalate based on trivacant [B-α-AsW9O33]9− {AsW9} fragments and an organic ligand, imidazole (C3H4N2). Compound 1 was further characterized by single-crystal X-ray diffraction, PXRD, IR spectroscopy, UV-Vis spectroscopy, ESI-MS, elemental analysis and TGA. Single-crystal X-ray diffraction data reveal that the polyanion consists of four trivacant Keggin-type polyanion {AsW9} building blocks bridged by four {WO6} units, leading to a crown-shaped tetrameric structure [(AsW9O33)4(WO2)4{Ru3.2(C3H3N2)2}]20.4−. The ESI-MS result reveals that the polyanion unit has excellent structural integrity in water. Moreover, the catalysis study of 1 was also further investigated, and the experimental results indicate heterogeneous catalyst 1 presents high efficiency (yield = 98%), excellent selectivity (>99%), and good recyclability for the oxidation of 1-(4-chlorophenyl)ethanol to 4′-chloroacetophenone with commercially available 70% aqueous tert-butyl hydroperoxide {TBHP (aq.)} as the oxidant at room temperature.

A nanoscale polyoxoniobate based on trivalent nickel complex and Lindqvist-type cluster, [Ni(en)3]2[H2Nb6O19]·8H2O (abbreviated as NEN) (en = ethylenediamine, C2H8N2) has been synthesized and structurally characterized by elemental analyses, IR spectrum, UV–visible spectra, X-ray photoelectron spectrum (XPS), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. Structural analysis shows that NEN is an ionic compound, in which the cations are two trivalent nickel complexes [Ni(en)3]3+ and the anion is a Lindqvist-type polyoxoniobate [Nb6O19]8− cluster. Notably, NEN can catalyze the production of reactive oxygen species efficiently in aqueous solution system.

Recently, we demonstrated that the in situ formation of a building block is an attractive synthesis strategy for creating novel clusters with controllable structures. Herein, we present the design and synthesis of the first tantaloselenite polyoxoanion [Se4(TaO2)6(OH)4O17]4- (1) and a series of lanthanide derivatives (RE3+ = Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+). In total, we report seven clusters that vary in both composition and structure but which share the same {Se4(TaO2)6} building block. The compounds are fully characterized by single-crystal X-ray diffraction, IR spectra, TG, and PXRD and their decolorization properties for RhB have also been investigated. Compound 1 exhibits good photocatalytic activity for the decolorization of RhB while the introduction of lanthanide into the framework can also maintain this activity.

Three sandwich-type TM-containing (TM = transition metal) organophosphonate-based polyoxotungstate clusters, [TM(H2O)4(SeW6O21)2{Co(OOCCH2NCH2PO3)2}3]12− (TM = Co, Ni), have been successfully synthesized, which are the first reported TM-containing organophosphonate-based selenotungstates. They were structurally characterized by PXRD analyses, IR spectroscopy, TGA analyses, etc. Magnetic measurements show that all three compounds exhibit antiferromagnetic interactions. Besides, Co1 can be used as an efficient heterogeneous catalyst in the Knoevenagel condensation of benzaldehyde and ethyl cyanoacetate under mild conditions (60 °C), and exhibits satisfactory conversion (93%) and high selectivity (99%).

By self-assembly of the KVO3 raw material with propionate ligand using hydrazine hydrate as reducing agents in conventional aqueous solution, a novel propionate-functionalized polyoxovanadate K2[V10O16(OH)6(CH3CH2CO2)6]·20H2O (1) has been successfully synthesized and further structurally characterized by IR spectrum, powder X-ray diffraction (PXRD), thermogravimetric (TG), and single-crystal X-ray diffraction analysis. Structural analysis demonstrates that the polyanion [V10O16(OH)6(CH3CH2CO2)6]2− of 1 is composed of the {V10}-based polyoxovanadate which is further anchored by 6 propionate ligands to form a propionate-stabilized decavanadate. The {V10} building unit of 1 is completely different from the classical [V10O28]6− ion. The catalytic property of 1 for the degradation of methylene blue (MB) was investigated, and the result indicates that 1 exhibits excellent catalytic activity for the degradation of MB.

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.

The reaction of the lacunary polyoxotungstate [B-α-BiW9O33]9− with Cu(Ac)2·H2O in the presence of diethylenetriamine under hydrothermal conditions generating a new 2-D layer-like organic-inorganic hybrid tungstobismuthate [Cu(dien)(H2O)]2[Cu2(dien)2]2H2[Bi2W20O70]·15H2O (1) (dien = diethylenetriamine). 1 has been carefully characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis (TGA), X-ray single-crystal diffraction. 1 crystallizes in the orthorhombic Pbca space group with a = 21.077(2) A, b = 21.788(2) A, c = 22.821(2) A, V = 10480.1(17) A3, Z = 4, GOOF = 1.043, R1 = 0.0454, wR2 = 0.0710. Structural analyses show that 1 exhibits an organic-inorganic hybrid 2-D layer-like architecture constructed by [Bi2W20O70]14− polyanions by means of the [Cu2(dien)2]4+ bridges. Notably, the dien ligand presents two kinds of coordination modes in 1, which has been rarely observed in previously reported polyoxometalates. The magnetic study of 1 demonstrates the existence of ferromagnetic coupling interactions between Cu2+ ions in dimeric [Cu2(dien)2]4+ groups.

Three oxalate-bridging lanthanide-based polyoxometalates (Ln-POMs) K17Na2H5[{(As2W19O67(H2O))Ln(H2O)2}2(C2O4)]·50H2O. [Ln = Sm3+ (1), Pr3+ (2), and Ce3+ (3)] were successfully synthesized. The structures were further characterized by single-crystal X-ray diffraction analyses, Raman spectroscopy, elemental analyses, powder X-ray diffraction (PXRD), IR spectra, UV/vis diffuse reflectance spectroscopy, and thermogravimetric analysis (TGA). The structural characterization study reveals that Ln-POMs 1-3 crystallize in the form of the triclinic space group P1[combining macron] and consist of an oxalate bridging di-Ln3+-incorporated H-shaped dimer, which can also be viewed as a combination of two half-units {Ln(As2W19O67(H2O))(H2O)2}222- related by an inversion center. It is worth noting that the opening angle (33.01°) from the [As2W19O67(H2O)]14- fragment in 1-3 is less than that of the [As2W19O67(H2O)]14- precursor (40.99°). Furthermore, the stability of 1-3 in aqueous solution and their solid-state photoluminescence properties have also been investigated in this work.

Three [α2-P2W17O61]10--based lanthanide-containing polyoxometalates (LCPs) [N(CH3)4]3H8{Ln(H2O)7[Ln(H2O)3Ln(H2O)4(α2-P2W17O61)2]}·48H2O [Ln = La3+ (1), Ce3+ (2), and Pr3+ (3)] were successfully obtained by the reaction of a trivacant Dawson-type precursor [P2W15O56]12- and lanthanide ions under hydrothermal conditions. The compounds 1-3 were fully characterized by single-crystal X-ray diffraction and a series of analytical methods, including elemental analyses, powder X-ray diffraction (PXRD), IR spectroscopy, Raman spectroscopy, UV/vis diffuse reflectance spectroscopy, and thermogravimetric analysis (TGA). Single-crystal X-ray diffraction analyses indicated that 1-3 were isostructural and exhibited a 2D network architecture through the alternative connection of [α2-P2W17O61]10- and lanthanide ions. The photoluminescence properties of 1-3 were investigated at room temperature, and 3 displayed the characteristic emissions of a Pr3+ emitting center, indicating that POMs can transfer energy and sensitize Pr3+ emissions. The reason for the weak emission intensity of Pr3+ emitting ions was because the radiationless losses via a charge-transfer Pr → W state negatively affected the emission of the Pr3+ ions in LCPs.

A monomeric phosphotungstate-supported rhenium carbonyl derivative, [N(CH3)4]6H4[P2W17O62{Re(CO)3}2]·25H2O (1), has been synthesized in a conventional solution system and structurally characterized by single crystal X-ray diffraction crystallography, IR spectroscopy, thermogravimetric (TG) analyses, X-ray powder diffraction (XRPD), and electrospray ionization mass spectrometry (ESI-MS). To our knowledge, this is the first time that the {Re2} fragment existing in the polyoxoanion has been observed in polyoxometalate-supported metal carbonyl derivatives. Moreover, UV-vis spectroscopy was employed to elucidate the stability of the polyoxoanion, and its electrochemical properties were also investigated. In particular, complex 1 could act as an efficient homogeneous catalyst for selective oxidation of thiophenes. For example, dibenzothiophene (DBT) undergoes up to 99% conversion and 99% sulfone selectivity in acetonitrile with 30% H2O2 as an oxidant.

Three tartrate-bridging lanthanide-based tungstoarsenate dimers K11H13[Ln3(H2O)8(OH)2(AsW9O33)(AsW10O35(C4O6H3))]2·nH2O (Ln3+ = Eu3+ (1Eu), n = 50; Tb3+ (2Tb), n = 34; C4O6H6 = tartaric acid) and K15H9[Dy3(H2O)15(OH)2(AsW9O33)(AsW10O35(C4O6H3))]2·21H2O (3Dy) have been synthesized and further characterized by elemental analyses, X-ray powder diffraction, IR spectra, thermogravimetric analyses and single-crystal X-ray diffraction. Structural analyses indicate that all the polyanions of 1Eu–3Dy are isostructural, and are composed of two identical asymmetric sandwiched subunits [Ln3(H2O)8(OH)2(AsW9O33)(AsW10O35(C4O6H3))]12– interlinked by two tartrate ligands. Furthermore, the photoluminescence and variable-temperature magnetic properties of 1Eu, 2Tb and 3Dy have also been investigated.

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...

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.

Polyoxometalates (POMs), a unique class of metal-oxygen clusters with an oxygen-rich surface and high negative charge, have attracted great attention due to their unique structural variety and excellent physicochemical properties. In addition, organophosphonates, as an important kind of organic ligands with wide various and rich coordination modes, have lots of potential applications in materials, medicine and catalysis. Therefore, the synthesis of organophosphonates-based POMs with novel structure and good property is of contemporary interest. Polyoxotungstates (POTs) are viewed as one of the most important and vibrant subfamilies in POM chemistry and have been increasingly used as building blocks for the construction of systems with inorganic-organic hybrid compounds. Nevertheless, compared to the abundant derivatives of polyoxomolybdates and polyoxovanadates, organophosphonate-based POTs have been rarely studied. It is commonly that most of the structures just anchor some common transition metals (Co, Ni, Cu) or even do not anchor any metal ions. In contrast, POTs incorporated with lanthanide (Ln) ions and organophosphonate ligands have been rarely explored. Up to now, only a series of Ln-containing organophosphonatebased POTs have been reported. Moreover, the Ln ions possess the 4f electrons, leading to interesting properties such as magnetic and photoluminescent properties. It appeals us to devote in investigating the interesting Ln-containing organophosphonate-functionalized POTs. Herein, a new organic-inorganic hybrid CsH[Pr(H2O)4(AsW9O33)(W2O3)(O3PCOHCH3PO3)Pr(H2O)7]2∙19H2O ( 1 ) has been successfully synthesized by reaction of K14[As2W19O67(H2O)], HEDP and PrCl3∙6H2O in a conventional aqueous method. This structure was structurally characterized by single-crystal X-ray diffraction, TG analysis, PXRD and IR spectrum. The results show that compound 1 exhibits a three-dimensional (3D) framework structure which is consist of the S-shaped inorganic building block {[(AsW9O33)(W2O3)]2}, four Pr ions and two organophosphonate groups {O3PCOHCH3PO3}. Variable temperature magnetic susceptibility of the solid state 1 was also measured at 1.8−300 K with an applied field of 1 kOe. At 300 K, the χ m T product is 6.42 cm3 K mol-1, close to the value of 6.40 cm3 K mol-1 expected for four uncoupled PrIII ions ( L =5, 3H4, g =4/5, S =1). With cooling, the χ m T value decreases continuously down to a value of 5.16 cm3 K mol-1 at 101 K. As the temperature further decreases, the χ m T value starts to decrease rapidly and reaches a minimum of 0.43 cm3 mol-1 K at 1.8 K. This behavior indicates the antiferromagnetic exchange interactions and which is further confirmed by a negative Weiss constant θ = -39.02 K derived by fitting the Curie-Weiss law to the magnetic data between 68 and 300 K The near-infrared (NIR) emission spectra of 1 was also investigated at room temperature. Under the excitation at 448 nm, the NIR emission spectrum of 1 consists of three characteristic peaks of the PrIII ions at 871 nm (ID2→3F2), 1017 nm (ID2→3F4) and 1515 nm (1D2→1G4). Moreover, the NIR decay curve of 1 is fitted into a second-order exponential function with lifetimes of τ 1=4.76 μs (35.53%), τ 2=9.71 μs (64.47%). In the following work, other bridging ligand with different functional groups such as amino or carboxyl-functionalized organophosphonate will be introduced into this system to explore much more Ln-containing organophosphonate-based POTs with intriguing structures and properties.

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.

Three polyoxovanadate-based hybrids {[Ru(phen)3]2[V4O12]}·13H2O (1), [Ru(phen)3]2[V10O28]·15H2O (2), and [Ru(phen)3]2[V6O17]Cl·11H2O (3) (phen = 1,10-phenanthroline) were prepared under hydrothermal conditions and characterized by electron paramagnetic resonance (EPR) spectroscopy, infrared spectroscopy (IR), powder X-ray diffraction (PXRD), thermogravimetric (TG) analysis, X-ray photoelectron spectroscopy (XPS), and single crystal X-ray diffraction analysis. Although the structures of both the cyclic vanadate [V4O12]4− and the [V10O28]6− anions are well-known, interestingly, a novel 1-dimensional (1-D) coordination polymer [V6O17]n4n− anion was constructed from tetranuclear [V4O12]4− and dinuclear [V2O7]4− building blocks, which were linked alternately through corner-shared oxygen atoms. Furthermore, the negative charges of polyoxovanadate [V4O12]4−, [V10O28]6− and [V6O17]4− anions were balanced by two [Ru(phen)3]2+/3+ complex cations. The catalytic properties of compounds 1–3 for the oxidation of 1-phenyl ethanol by tert-butyl hydroperoxide (TBHP) were investigated, and the results demonstrated that 1 and 3 exhibited excellent catalytic activities for the oxidation of 1-phenyl ethanol under mild catalytic conditions.

The double-tartaric bridging Tm-substituted POM derivative [N(CH3)4]6K3H7[Tm(C4H2O6)(α-PW11O39)]2·27H2O (1) was successfully synthesized and well characterized by various physico-chemical analyses. Furthermore, the mixed Dy3+/Tm3+ ion-based POM derivatives [N(CH3)4]6K3H7[DyxTm1-x(C4H2O6)(α-PW11O39)]2·27H2O (3-8) were first synthesized and confirmed by PXRD and IR spectra, indicating compounds 3-8 are isomorphic with 1. The detailed analyses of Ln-O-W bond angle and coordinated aqua ligands around emitting Ln3+ ions have revealed that the mentioned negative factors do not effectively affect the luminescence of emitting Ln3+ ions in 1-8. Investigations of PL emissions reveal that 3-8 can display color-tunable PL properties, emitting color from blue to white to yellow. The study of time-resolved emission spectroscopy of 6 indicates the energy can transfer from the LMCT excited state of POM fragments to Tm3+ and/or Dy3+ ions. Furthermore, the decreased luminescent lifetime of Tm3+ ions in 3-8 reasonably verifies the energy transfer from Tm3+ to Dy3+ ions to efficiently facilitate emissions of the Dy3+ centre.

A 1-D infinite helical chain-like organic–inorganic hybrid arsenotungstate Na4H8[{Pr(H2O)2}2{As2W19O68}{WO2(mal)}2]·24H2O (mal = malate) (1) was prepared, which was characterized by elemental analyses, thermogravimetric (TG) analyses, IR spectroscopy, powder X-ray diffraction (PXRD) and X-ray single-crystal diffraction. Structural characterization revealed that 1 comprises the organo-functionalized [{As2W19O68}{WO2(mal)}2]18− polyanions hinged together by the Pr3+ ions forming a 1-D infinite helical chain-like architecture. The malate ligand may play a vital role to stabilize the structure of 1 by the formation of the five-membered W–O–C–C–O chelate ring. Solid state photoluminescence reveals that 1 features excitation wavelength-dependent emission properties, achieving a reversible emission color switching simply via changing the excitation wavelength. Time-resolved emission spectroscopy (TRES) indicates that the photoexcitation O → M ligand to metal charge transfer (LMCT) of arsenotungstate fragments can sensitize the Pr3+ ions through intramolecular energy transitions in 1.

A novel organic-inorganic hybrid polyoxometalate-based 3D framework K 5 H 4 {Ce 3 (H 2 O) 9 [As 2 W 21 O 72 (mal) 2 ]}·20H 2 O (1) (mal = malic acid) has been synthesized by the metastable precursor [As 2 W 19 O 67 (H 2 O)] 14 − , which was further characterized by IR spectrum, thermogravimetric analysis (TGA), and X-ray single-crystal diffraction. Structural analysis revealed that 1 consists of the organo-functionalized [As 2 W 21 O 72 (mal) 2 ] 18 − units linked together by the Ce 3 + ions resulting in 3D network-like architecture. Magnetic property studies indicate that obvious antiferromagnetic interactions exist in three Ce 3 + ions.

Two ruthenium-containing polyoxometalate-based hybrids (Ru-POMs), KH8[Ru3O(Trz)6Cl3]2[(NaO6)W6(H2O)6(AsW9O33)4]·28H2O (1) and H3[Ru3O(Trz)6Cl3]2[(WO)2W(OH)(AsW9O33)2]·6H2O (2), (Trz = 1,2,4-triazole), were successfully isolated by a one-step hydrothermal method under different acidic conditions and further characterized by single-crystal X-ray diffraction, powder X-ray diffraction (PXRD), IR spectroscopy, electrospray ionization and mass spectrometry (ESI-MS), thermogravimetric (TG) analyses and elemental analyses. Single-crystal X-ray diffraction analyses reveal two polyanions comprised of four/two identical trivacant Keggin-type polyanion building blocks, leading to the formation of tetrameric/dimeric assembly stabilized by additional metal–oxo cores, respectively. ESI-MS shows that the polyanion units [(NaO6)W6(H2O)6(AsW9O33)4]11− and [(WO)2W(OH)(AsW9O33)2]5− are intact in mixed solvent. Moreover, the two heterogeneous catalysts with trinuclear ruthenium cations were further investigated, and 1 was found to exhibit much higher yield (94.1%)/conversion (95.1%) and better selectivity (>99%) towards the oxidation of thioanisole to sulfoxide than 2.

A novel cubane-type Ni-substituted polyoxotungstate based on trivacant Dawson-type [P2W15O56]12 − unit with the formula of Na4H4[P2W15O56(W0.5Ni3.5)(OH)6(H2O)3]·18.5H2O (1) has been synthesized in aqueous medium and characterized by IR spectroscopy, EDX spectrum, thermogravimetric analysis and magnetic measurements. Structural analysis indicates that 1 consists of a trivacant Dawson-type unit [P2W15O56]12 − incorporated in a cubane-type {Ni3.5W0.5O7(OH)6(H2O)3} group. Magnetic studies show that the ferromagnetic Ni Ni exchange interactions exist in the cubane-type cluster.

A novel octa-nuclear cerium(III)-containing organic-inorganic hybrid polyoxometalate [N(CH3)4]8H16[{Ce(η1-C6H5NO2)2(H2O)6[Ce(H2O)3(α2-P2W17O61)]}{Ce(η2-C6H5NO2)2(H2O)5[Ce(H2O)(α2-P2W17O61)]}]2·90H2O (C6H5NO2 = isonicotinic acid) (1) was obtained, which had been hydrothermally synthesized and characterized by IR spectrum, thermogravimetric analysis (TGA), and X-ray single-crystal diffraction. Structural analysis indicated at 1 is composed of four lacunary Dawson-type units [α2-P2W17O61]10 − joined together by eight cerium cations forming an uncommon zigzag tetrameric structure with eight isonicotinic acids as the organic pendants coordinating to the cerium cations. Magnetic property studies indicate that obvious antiferromagnetic interactions exist in eight Ce3 + cations.

A hybrid polyoxometalate based on binuclear copper complex and α-Keggin-type silicotungstate [Cu2(4,4′-bpy) (Phen)2][SiW12O40] (abbreviated as CSW) (4,4′-bpy = 4,4′-bipyridine; Phen = 1,10-phenanthroline) has been synthesized and structurally characterized by elemental analyses, X-ray powder diffraction (XRPD), IR spectrum, X-ray photoelectron spectrum (XPS) and single-crystal X-ray diffraction. Structural analysis shows that CSW is an ionic compound, in which the cation is a binuclear copper complex [Cu2(4,4′-bpy) (Phen)2]4+ and the anion is a α-Keggin-type silicotungstate [SiW12O40]4– cluster. Notably, the Cu ions in the [Cu2(4,4′-bpy) (Phen)2] exist in the form of tri-coordination, which the phenomenon is very rare in polyoxometalates. Moreover, CSW can catalyze the production of reactive oxygen species efficiently.

A new organic-inorganic polyoxoniobate KNa[Co(en)3]2[(HNb6O19)Co(en)]2·30H2O (1) has been successfully synthesized under hydrothermal condition which has been characterized by single-crystal X-ray diffraction, IR spectrum, thermogravimetric analysis and X-ray photoelectron spectroscopy. Compound 1 crystallizes in Ibam space group with a = 19.0985(8) A, V = 27581(2) A3, Z = 8. X-ray structure analysis reveals that the title polyanion consists of a dimeric alignment constructed from two Lindqvist-type {Nb6O19} subunits via two {CoIII(en)} connectors.

A novel organophosphonate-based polyoxovanadate, Cs1·5Na3.5[H{V3(H2O)O3}{O3PC- (OH)(CH3)PO3}3]·15H2O (1) has been synthesized and further investigated by single-crystal X-ray diffraction analysis, IR spectrum, UV–vis spectroscopy, X-ray powder diffraction, thermogravimetric analysis and X-ray photoelectron spectroscopy. Single-crystal X-ray analysis reveals that compound 1 crystallizes in the triclinic space group P-1 with a = 9.506(3) A, b = 15.150(5) A, c = 17.915(6) A, V = 2437.9(14) A3 and Z = 2. Compound 1 exhibits a ring-shaped cluster with three branches of the 1-hydroxyethane 1, 1-diphosphonic acid [HEDP = H2O3P(OH)C(CH3)PO3H2] ligands. Furthermore, the magnetic property of compound 1 has also been studied.

The first example of wholly inorganic ruthenium-containing polyoxomolybdate Cs3Na6H[MoVI14RuIV2O50(OH)2]·24H2O (1) was isolated and systematically characterized by element analysis, infrared spectroscopy (IR), thermogravimetric analyses (TGA), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX) and single-crystal X-ray diffraction. Compound 1 is composed of an unprecedented {Mo14}-type isopolymolybdate with a di-ruthenium core precisely encapsulated in its center, exhibiting a three-tiered ladder-like structure. The title compound can act as an efficient heterogeneous catalyst in the transformation of 1-phenylethanol to acetophenone. This catalyst is also capable of being recycled and reused for at least ten cycles with its activity being retained under the optimal conditions.

The nature of carboxylic acid has a profound effect on constructing POM-based architectures. With different carboxylic acid ligands, three novel diphosphonate-containing compounds have been synthesized and further investigated by elemental analyses, single-crystal X-ray diffraction, IR spectroscopy, UV-vis spectroscopy, X-ray powder diffraction (XRPD), 31P NMR spectroscopy, cyclic voltammetric behavior and thermogravimetric (TG) analyses. [(HO3PCH2PO3)Mo6O18(O2CC6H4OH)2]5− (1a) shows a ring-shaped cluster with a {Mo6} plane framework. [{(HO3PCH2PO3)Mo6O18(CH3CO2)2}2Na2(H2O)2]8− (2a) is a reverse symmetrical “crown-type” structure and the subunits are linked by two Na–O(1W)–Na bridges. The polyanion [{(O3PCH2PO3)(Mo6O18(H2O)2)(O2CCH2CO2)}2(Mo2O5)2(μ3-O)2]12− (3a) appears as an “S-shaped” structure with a centre of inversion.

A series of inorganic–organic hybrid heteropolyoxomolybdates built from [TeMo6O21]2− polyoxoanions and multicarboxylic acids including (C3N2H5)4H6[(TeMo6O21)2{O2C(CH2)2CO2}3]·9.5H2O (1), (C3N2H5)8H2[(TeMo6O21)2{O2C(CH2)6CO2}3]·3.5H2O (2) and (CN3H4)16H4[(TeMo6O21)4{C6H3(COO)3}4]·16H2O (3) have been synthesized arising from the reactions of (NH4)6Mo7O24·4H2O, Na2TeO3/TeO2 and the corresponding multicarboxylic acids in an aqueous medium. X-ray single crystal diffraction, X-ray powder diffraction (XPRD), elemental analyses, inductively coupled plasma (ICP) spectra, IR spectra, UV spectra and thermogravimetric (TG) analyses have been implemented. Crystal structure analyses reveal that both compounds 1 and 2 are dimers, while 3 is a tetramer, however, they contain the same {TeMo6} unit which consists of a six-membered MoO6 octahedral ring capped by one {TeO3} trigonal pyramid. Compounds 1–3 exhibit intriguing allochroic properties. They can change color from white to blue/green when heated. Upon the irradiation of a xenon lamp (full wave-band, P = 300 W), their color can change from white to reddish brown.

Eight new lanthanide derivatives containing 6-peroxoniobio-4-phosphate building block, [LnIII(H2O)6]2[H4(NbO2)6P4O24]·nH2O [Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), Er (6), Tm (7), Yb (8), 1–5, 7, 8 n = 12; 6 n = 9], have been successfully obtained using an in-situ strategy and fully characterized in the solid state by single-crystal X-ray diffraction, IR spectra, TG-MS, PXRD. Structural analyses indicate that these isostructural polyanions 1–8 consist of one [P4(NbO2)6O24]10− (P 4 (NbO 2 ) 6 ) clusters and two pendant Ln3+ cations. In these compounds, P 4 (NbO 2 ) 6 clusters are connected by lanthanide cations to form extended two-dimensional architectures. The approach takes advantage of the ability of in-situ formed P 4 (NbO 2 ) 6 cluster to build frameworks by using it as ligands to lanthanide ions. The photoluminescence (PL) and lifetime decay behaviors of 1, 3 and 4 in solid state have been performed at room temperature. The PL emission of 1, 3 and 4 is mainly derived from the characteristic 5D0→7FJ (J = 1, 2, 3, 4), 5D4→7FJ (J = 6, 5, 4, 3) and 4F9/2→6H J (J = 15/2, 13/2, 11/2) transitions of the EuIII, TbIII and DyIII cations, respectively.

Four structurally intriguing members of a new family of lanthanide (Ln)-containing organophosphonate-functionalized polyoxotungstates with the general formula K2[Ln(H2O)4(AsW9O33)(W2O3)(O3PCOHCH3PO3)Ln(H2O)7]2·15H2O [Ln = Ce (1Ce), Nd (2Nd), Sm (3Sm) and Eu (4Eu)] were directly isolated by controlling the reaction parameters and well established by single-crystal X-ray diffraction, PXRD analyses, IR spectra, elemental analyses, TG and EDX analyses. All the four three-dimensional frameworks consist of the S-shaped inorganic building block {[(AsW9O33)(W2O3)]2}, two organophosphonate groups {O3PCOHCH3PO3} and four Ln ions. The magnetic properties of the four compounds and the solid-state photoluminescence properties of 2Nd, 3Sm, and 4Eu were also fully investigated.

A new organic-inorganic hybrid dimeric phosphotungstate, [N(CH3)4]6K3H7[Ho(C4H2O6)(α-PW11O39)]2·27H2O (1), was obtained by the reaction of [P2W19O69(H2O)]14− precursor with Ho3+ ions in the tartaric acid aqueous medium, which was characterized by IR spectrum, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), elemental analyses, Uv–Vis spectroscopy and single-crystal X-ray diffraction. The polyanion [Ho(C4H2O6)(α-PW11O39)]216− contains two mono-Ho substituted Keggin-type fragments linked together by two tartaric acid groups. This photoreactive compound exhibits reversible photochromism which can change from light pink to blue upon UV irradiation. The solid-state photoluminescence spectra of 1 at room temperature displays the characteristic Ho3+ ions emission patterns of 5S2/5F4→5I8 and 5F5→5I8. Simultaneously, the CIE chromaticity diagram has been acquired according to corresponding emission spectra of 1.

The hydrothermal reaction of Lindqvist [Nb6O19]8−, sodium pyrophosphate with transition metal ion (CoII) in the presence of amine results in one novel transition-metal-linked trivacant Keggin heteropolyniobate: K6Na17[H3{Co(H2O)3}2(P4Nb9O40)2]·24H2O. The compound has been structurally characterized by EDS, IR spectra, XPS, thermogravimatric analysis, and X-ray crystallography. The solid-state structure is composed of two {P4Nb9} fragments linked by [Co(H2O)6]2+ ions, further leading to the formation of 2D sheet-like architecture. Interestingly, the Nb-oxo cluster achieves transformation in situ.

A structurally intriguing polyanion, [{Nb4O6(OH)4}{Nb6P2W12O61}4]36– (2), was directly formed by controlling the reaction parameters and characterized by single-crystal X-ray diffraction, IR spectroscopy, and elemental analyses. Polyanion 2 is the first niobium-substituted Wells–Dawson-based tetramer and contains the largest Nb28 cluster encapsulated by four hexalacunary Wells–Dawson frameworks. The activities of compounds Na12[H24-2]·24H2O (2a), K12[H2P2W12O48]·24H2O, and K7[HNb6O19]·13H2O against three human tumor cell lines were investigated in vitro. The preliminary results revealed that 2a could efficiently inhibit the growth of the human breast cancer MCF-7 cells. Interestingly, the activity of 2a is significantly better than those of the simple reagents.

Two new organic–inorganic polyoxometalates [Cu(dien)(H2O)]2{[Cu2(dien)2(OH)]2[Cu4(B-α-XW9O33)2]}·4H2O (X = Sb, 1; X = As, 2) (dien = diethylenetriamine) were hydrothermally synthesized and characterized by elemental analysis, IR spectra, thermogravimetric (TG) analyses, and single-crystal X-ray diffraction. Both compounds are constructed from one four-coordinate [Cu(dien)(H2O)]2+, one {[Cu2(dien)2(OH)]2[Cu4(B-α-XW9O33)2]} building unit, and four water molecules of crystallization. Structural analysis shows that the sandwich-like polyoxotungstate cluster anions [Cu4(B-α-XW9O33)2]10− are linked by six adjacent dimeric cations [Cu2(dien)2(OH)]3+ into a 2-D architecture with a (6,3)-connected topology. Magnetic measurements of 1 and 2 exhibit the presence of antiferromagnetic interactions within the tetranuclear-CuII cluster.

A new nano-linear Zn-substituted Strandberg-type phosphomolybdate (H2en)6{[Zn(H2O)4](P2Mo5O23)}3·10H2O (abbreviated as ZPM) (en = ethanediamine) has been synthesized and structurally characterized by elemental analyses, X-ray powder diffraction (XRPD), IR spectrum, UV–Vis spectroscopy, scanning electron microscope with energy dispersive X-ray (SEM-EDX), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. Structural analysis shows that [Zn(H2O)4]2+ as a linker connected with two adjacent [P2Mo5O23]6– clusters to form a 1-D structure. Notably, the chemical environment of three adjacent {[Zn(H2O)4](P2Mo5O23)}4– are different in solid state. To our knowledge, the phenomenon is very rare in polyoxometalates. Moreover, ZPM can catalyze the production of ROS efficiently and can inhibit the proliferation of E. coli by the synergy effect of Zn2+ and [P2Mo5O23]6– clusters.

An organic–inorganic hybrid sandwich-type tungstoantimonate [Cu(en) 2 (H 2 O)] 4 [Cu(en) 2 (H 2 O) 2 ][Cu 2 Na 4 ( α -SbW 9 O 33 ) 2 ]·6H 2 O ( 1 ) has been synthesized by reaction of Sb 2 O 3 , Na 2 WO 4 ·2H 2 O, CuCl 2 ·2H 2 O with en (en=ethanediamine) under hydrothermal conditions and structurally characterized by elemental analysis, inductively coupled plasma atomic emission spectrometry, IR spectrum and single-crystal X-ray diffraction. 1 displays a centric dimeric structure formed by two equivalent trivacant Keggin [ α -SbW 9 O 33 ] 9− subunits sandwiching a hexagonal {Cu 2 Na 4 } cluster. Moreover, those related hexagonal hexa-metal cluster sandwiched tungstoantimonates have been also summarized and compared. The variable-temperature magnetic measurements of 1 exhibit the weak ferromagnetic exchange interactions within the hexagonal {Cu 2 Na 4 } cluster mediated by the oxygen bridges.

A novel Dy(III)-based organodiphosphonate-functionalized polyoxomolybdate [NH2(CH3)2]3{[Dy(DMF)2(H2O)4]3[Dy(DMF)3{(Mo3O8)(O3PCOCH3PO3)}3]2}∙6DMF·2H2O (1) (DMF = N,N-Dimethylformamide) has been synthesized and characterized by elemental analysis, IR spectrum, thermogravimetric analysis (TG), UV spectroscopy, fluorescence spectroscopy and single-crystal powder X-ray diffraction (PXRD). Compound 1 is composed of two monocapped [Dy(DMF)3{(Mo3O8)(O3PCOCH3PO3)}3]6 − subunits and three [Dy(DMF)2(H2O)4]3 + coordination cations, which contain an internal capsule. The UV spectra indicate that compound 1 is stable in the pH range of 2.76–4.75.

A new 2-D network tetra-Zn II -substituted sandwich-type Keggin tungstoarsenate {[Zn(dap) 2 (H 2 O)] 2 [Zn(dap) 2 ] 2 [Zn 4 (Hdap) 2 (B- α -AsW 9 O 34 ) 2 ]}·4H 2 O ( 1 ) (dap = 1,2-diaminopropane) has been synthesized by combining the conventional aqueous solution method and the hydrothermal method and structurally characterized by elemental analyses, X-ray powder diffraction (XRPD), IR spectrum, thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. Structural analysis shows that 1 displays an interesting 2-D (4,4)-topological network constructed by tetra-Zn II -substituted sandwich-type Keggin tungstoarsenate units and [Zn(dap) 2 ) 2+ ] linkers. To our knowledge, 1 represents the first 2-D network Zn-substituted sandwich-type tungstoarsenate. The fluorescent properties of 1 have also been investigated.

An inorganic–organic hybrid hexa-copper-substituted germanotungstate Na{sub 2}[Cu(dap){sub 2}]{sub 2}[Cu(dap){sub 2}] ([Cu{sub 6}(H{sub 2}O){sub 2}(dap){sub 2}][B-α-GeW{sub 9}O{sub 34}]{sub 2})·4H{sub 2}O (1) (dap=1,2-diaminopropane) has been hydrothermally prepared and characterized by elemental analyses, inductively coupled plasma atomic emission spectrometry (ICP–AES) analyses, IR spectra, powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and single-crystal X-ray diffraction. 1 displays the six-connected 3D network with the long topological (O′Keefe) vertex symbol is 4·4·6{sub 4}·4·4·4·4·6{sub 4}·4·4·4·6{sub 4}·4·4·4 and the short vertex (Schlafli) symbol of 4{sup 12}6{sup 3}. Magnetic measurements indicate that there are the overall ferromagnetic exchange interactions in the belt-like hexa-Cu{sup II} cluster in 1. Furthermore, the electrochemical behavior and electrocatalysis of 1 modified carbon paste electrode (1-CPE) have been studied. The reductions of nitrite, bromate and hydrogen peroxide are principally mediated by the W{sup VI}-based wave. - Graphical abstract: A hexa-Cu{sup II} sandwiched germanotungstate has been synthesized and structurally characterized. The magnetic, solid-state electrochemical and electrocatalytic properties have been investigated. Display Omitted - Highlights: • Transition-metal substituted polyoxometalates. • Hexa-copper-substituted germanotungstate. • Six-connected 3D network. • Electrocatalytic reduction of nitrite, bromate and hydrogen peroxide.

Two novel 1D copper-bridged tetrahedral polyoxometalate nanoclusters with tetrameric rare-earth cores and germanotungstate vertexes, Na3H7[Cu(en)2]5[Cu(en)2(H2O)]2[RE4Ge4W46O164(H2O)3]·nH2O (RE = GdIII, n = 25 for 1; RE = YIII, n = 23 for 2; en = ethylenediamine), have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, thermogravimetric analysis (TGA), and single-crystal X-ray diffraction. The most prominent structural feature of 1 and 2 consists of unprecedented tetrahedral RE-substituted germanotungstate nanoclusters {[(α-GeW11O39RE)2(μ3-WO4)(α-GeW11O39RE(H2O))](μ4-WO4)[α-GeW11O39RE(H2O)2]}24–, in which four mono-REIII-substituted Keggin [α-GeW11O39RE(H2O)n]5– (n = 0, 1, 2) moieties are combined together with the aid of two WO42– connectors. What’s more interesting is that adjacent tetrahedral nanoclusters are interconnected with each other via [Cu(en)2]2+ bridges, forming a 1D extended chain architecture. To our knowledge, 1 and 2 are the first polyoxometa...

A novel compound based on saturated Wells–Dawson type phosphomolybdate, [Cu(H2O)4]3[P2Mo18O62]·12H2O (1) has been synthesized by the conventional solution method and characterized by elemental analysis, IR spectrum, UV spectrum, thermogravimetric analysis, electrospray ionization mass spectrometry (ESI-MS), electrochemistry and single-crystal X-ray diffraction. X-ray structural analysis reveals that 1 exhibits the 6-connected 2D topological network with the Schlafli symbol of (3649).

A novel organic–inorganic hybrid sandwich-type germanotungstate [enH2]8[Fe4(en)(α-GeW9O34)2] [Fe4(en)2(α-GeW9O34)2]·en·14H2O has been synthesized by reaction of K8Na2[A-α-GeW9O34]·25 H2O, FeCl3, Ce(NH4)4(SO4)4·4H2O and en (en = ethylenediamine) under hydrothermal conditions and characterized by elemental analyses, IR spectrum, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS) and single-crystal X-ray diffraction. To our knowledge, 1 represents the first organic–inorganic hybrid sandwich-type germanotungstate with discrete [Fe4(en)2(α-GeW9O34)2]8 − polyoxoanions and 1-D [Fe4(en)(α-GeW9O34)2]n8n − polymeric chains in polyoxometalate chemistry. Thermogravimetric curve of 1 between 25 and 700 °C indicates two steps of weight loss. Variable-temperature magnetic susceptibilities of 1 exhibit the ferromagnetic interactions within the belt-like tetra-FeIII clusters mediated by the oxygen bridges.

Two hybrid organic–inorganic organobisphosphonate polyoxomolybdates, Na4H2[(Mo3O8)2(O){O3PC(O)(CH2-3-C5NH5)PO3}2]·12H2O (1) and Na8[(Mo3O8){O3PC(O)(CH2-3-C5NH5)PO3}]4·30H2O (2), have been successfully synthesized and structurally characterized. Compounds 1 and 2 are prepared in aqueous solution by one-pot reaction of 1-hydroxo-2-(3-pyridyl) ethylidenebisphosphonate (risedronic acid) with molybdate. Structural analysis reveals that the two polyanions are composed of the same building blocks and can be described as a dimeric and tetrameric assembly of [(Mo3O8){O3PC(O)(CH2-3-C5NH5)PO3}]2– subunits, respectively. Elemental analysis, IR spectra, thermogravimetric analysis, and luminescence properties of the compounds have been studied in the solid state. The compounds are also characterized in the solution by multinuclear 31P NMR spectrometry, which evidences a subtle equilibrium between some species, and the results indicate that 1 presents two conformers of these hexanuclear polyanions in solution, whereas 2...

By controlling the pH of the reaction system, a dilacunary γ-Keggin silicotungstate [Cu(en)2(H2O)][H2en]{γ-SiW10O36[Cu(en)2(H2O)]2}·7.5H2O (1) (en = ethylenediamine) has been hydrothermally synthesized by the reaction of CuCl2 with α-H4SiW12O40 and characterized by IR spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. The product is prepared in the pH range 7.9–8.2, which reveals that pH plays a key role in the assembly of saturated α-H4SiW12O40 to dilacunary [γ-SiW10O36]8− polyoxometalate. The polyoxoanion {γ-SiW10O36[Cu(en)2(H2O)]2]}4− of 1 presents a rare [γ-SiW10O36]8−-retaining structure, in which two lacunary sites of [γ-SiW10O36]8− are unoccupied, meanwhile, two [Cu(en)2(H2O)]2+ groups are grafted on either side of the [γ-SiW10O36]8− unit by Cu–O–W bond.

Three new B-Anderson type polyoxometalates, [(C6H5NO2)2Ln(H2O)6](CrMo6O24H6)·2C6H5NO2·6H2O (Ln = Sm 1, Dy 2 and Er 3), have been synthesized in aqueous solution and structurally characterized by single-crystal X-ray diffraction, IR spectra, UV spectroscopy, and fluorescence spectroscopy. Crystal structure analysis reveals that these three compounds have the same composition and are isostructural, assembled by B-Anderson type polyoxoanion [CrMo6O24H6]3−, rare-earth ions, and ligands. UV spectroscopy shows that 1 is stable when pH is 4.50–5.83. The fluorescence spectra of 2 indicate that both rare-earth ions Dy3+ and pyridine-4-carboxylic acid ligands function in the charge transition of the compound.

A new compound H8[NaCu5Cl(H2O)3(B-α-AsW9O33)2] 24H2O (1) is synthetized by the reaction of the CuCl2 2H2O and Na27[NaAs4W40O140] 60H2O in aqueous solution, which is constructed from a {Cu5Na} hexagon moiety sandwiched by two trilacunary [B-α-AsW9O33]9− units. The structure is determined by single-crystal X-ray diffraction technique and further characterized by IR spectroscopy. Single-crystal X-ray diffraction analysis reveals that 1 is built by two trilacunary [B-α-AsW9O33]9− units incorporating a {Cu5Na} hexagon moiety and further linked to each other to form an infinitely extended 2-D network via Cu–O–W bridges. Notably, magnetic measurement demonstrates that the occurrence of intramolecular ferromagnetic Cu–Cu interactions within {Cu5Na} hexagon moiety.

A rare monocapped trivacant Keggin fragment [A-α-AsIIIAsVMo9O34]6– has been captured and an organic-inorganic hybrid arsenomolybdate (H2en)[Ni(en)2(H2O)]{[Ni(en)2][AsIIIAsVMo9O34]}∙3H2O (1) was obtained under hydrothermal conditions. The structure of 1 was determined by X-ray single-crystal diffraction and further characterized by IR spectroscopy, X-ray powder diffraction (XRPD), scanning electron microscope with energy dispersive X-ray (EDX-SEM) and X-ray photoelectron spectroscopy (XPS). Single-crystal structural analysis indicates that 1 contains the peculiar monocapped trivacant [A-α-AsIIIAsVMo9O34]6– fragment derived from the rare trivacant Keggin type [A-α-AsVMo9O34]9– unit capped by a triangular pyramidal {AsO3} group. 1 represents the first Ni-substituted inorganic-organic arsenomolybdate containing the [A-α-AsIIIAsVMo9O34]6– subunit.

An organic–inorganic hybrid 1-D double-chain CuII–YIII heterometallic silicotungstate [Cu(dap)2(H2O)]2 {Cu(dap)2[α-H2SiW11O39Y(H2O)2]2}·10H2O (1) has been synthesized by reaction of Na10[A-α-SiW9O34]·18H2O, CuCl2·2H2O, YCl3 and dap (dap = 1,2-diaminopropane) under hydrothermal conditions and characterized by elemental analyses, IR spectrum, UV spectrum and single-crystal X-ray diffraction. 1 exhibits a novel 1-D double-chain structure constructed from dimeric CuII–YIII heterometallic silicotungstate units. To our knowledge, 1 is the first organic–inorganic hybrid 1-D double-chain CuII–YIII heterometallic polyoxometalate. Thermogravimetry-differential thermal analysis of 1 has been measured from 25 to 750 °C and the thermogravimetric curve indicates two steps of weight loss.