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Abstract: A novel double-Dawson-anion-templated, triangular trinuclear Cu-trz unit-based metal–organic framework [CuII 8(trz)6(μ3-O)2(H2O)12][P2W18O62]·4H2O (1) (Htrz=1,2,4-triazole), has been hydrothermally synthesized and characterized by routine methods. Compound 1 is the first example of the Cu3-triad triangular unit-based three-dimensional (3D) metal–organic framework templated by double [P2W18O62]6− polyoxoanions. Furthermore, the electrochemical property of compound 1 has been studied. [Copyright &y& Elsevier]

Abstract: Two new compounds based on Weakley-sandwich-type polyanion (WSP), H2[Mn(en)2]2[Mn(en)2(H2O)]2[Mn4(H2O)2(PW9O34)2]·9H2O (1) and Na2[Co(en)2]2[{Co(en)2(H2O)]2[Co4(H2O)2(PW9O34)2]·9H2O (2) (en=ethylenediamine), have been synthesized by the hydrothermal reaction of the trivacant Keggin polyoxoanion [a-A-PW9O34]9− with transition metal ions and en, and structurally characterized by routine physical methods and single-crystal X-ray diffraction. Compound 1 represents a 1D chain structure made up of WSPs and [Mn(en)2]2+ ions. Compound 2 represents a 2D layer structure formed by the interconnection of WSPs, [Co(en)2]2+ and Na+ ions. Compounds 1 and 2 represent the first example of high-dimensional construction based on WSPs and transition metal complexes (TMCs), in which the water molecules located on the featured tetra-metal unit are still remained, and exhibit the property of sorption/desorption of water molecules. [Copyright &y& Elsevier]

Abstract: A novel one-dimensional Wells–Dawson-based compound H2(bbi)0.5[Ni(phen)(bbi)2]2[P2W18O62] (phen=1,10′-phenanthroline, bbi=1,1′-(1,4-butanediyl)bis(imidazole)), has been prepared under the hydrothermal conditions and structurally characterized by elemental analysis, cyclic voltammetry, IR and XPS spectra and single-crystal X-ray diffraction. The title compound exhibits an interesting wavelike chain constructed from Dawson type polyoxoanion and mixed rigid and flexible ligands decorated [Ni(phen)(bbi)2]2+ cationic complex. It represents the first example of polyoxometalate that built from the rigid and flexible ligands at the same time. [Copyright &y& Elsevier]

Abstract: By introducing the flexible 1,1′-(1,4-butanediyl)bis(imidazole) (bbi) ligand into the Keggin system, a novel multi-chain compound, (bbi)1.5[Cu(bbi)]4.5[PW12O40]1.5 (1) was synthesized under the hydrothermal conditions. It was characterized by elemental and TG analysis, IR and XPS spectra, cyclic voltammetry, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. Compound 1 features in two sorts of polyoxometalates (POMs) chains, the poly-chain of [Cu(bbi)]4.5[PW12O40] and the single-chain of (bbi)[PW12O40]0.5, induced by the POM clusters. [Copyright &y& Elsevier]

Abstract: A novel nanosized biological active multilayer film composed of polyoxometalate (POM) anion α-[SiW11O39Co(H2PO4)]7−(abbr. SiW11Co–PO4) and poly(diallyldi methylammonium chloride) (abbr. PDDA) was fabricated by layer-by-layer self-assembly (LBL). The composition and growth processes of the films have been determined by X-ray photoelectron spectra (XPS) and ultraviolet-visible absorption spectra (UV). The composite film was formed by the alternate adsorption of SiW11Co–PO4 and PDDA, and the deposition process was quantitative and highly reproducible from layer to layer. The morphology of the film was studied by atomic force microscopy (AFM), which showed that the film was relatively uniform and smooth, and POM anions aggregated into nanoclusters distributing on the surface uniformly. The film exhibited favorable electrochemical behavior of POM indicated by cyclic voltammetry (CV). The film can immobilize the DNA molecules via Mg2+-bridging medium. [Copyright &y& Elsevier]

Abstract: A novel photosensitive organic–inorganic composite film incorporating polyoxometalate, K7[SiW11O39Co(H3P2O7)] (SiW11CoPP), and diazoresin (DR) has been prepared via layer-by-layer (LBL) self-assembly. Under UV irradiation, followed the decomposition of diazonium in DR, the ionic bonds between the adjacent interfaces of the multilayer film convert to covalent bonds. The LBL multilayers were characterized by UV–vis spectroscopy, X-ray photoelectron spectra (XPS), atomic force microscopy (AFM), FTIR spectrum, cyclic voltammograms (CV), and electron spin resonance (ESR) measurements. UV spectroscopy shows that the deposition process is regular and highly reproducible from layer to layer. XPS spectra confirm the incorporation of DR and SiW11CoPP into the films. Atomic force microscopy image indicates that the film surface is uniform and smooth. Solvent etching experiment proves that the film has significant stability towards polar solvent. Electrochemical behavior of the multilayers is investigated. [Copyright &y& Elsevier]

A photoluminescent multilayer film based on Keggin-type polyoxometalate PMo12O403- (PMo12) and transition metal complex tris(2,2-bipyridine) ruthenium [Ru(bpy)3]2+ (Ru(bpy)) was prepared by using layer-by-layer assembly(LBL). The formation of multilayer film was monitored by ultraviolet absorption spectra. The absorption intensity of characteristic peaks increase with a four-layer cycle, indicating that the LBL assembly film grow linearly and reproducibly from layer to layer. The composition of the film was measured by X-ray photoelectron spectrum (XPS). The data of XPS confirmed the presence of the expected elements. The film exhibited photoluminescence arising from π*-t2g ligand-to-metal transition of Ru(bpy) and redox activity attributing to molybdenum-centered redox processes of PMo12. The surface morphology of multilayer film was characterized by atomic force microscopy (AFM). The result shows that the film had a smooth surface with root-mean-square (rms) roughness ca. 1.363 nm for {PEI/(PSS/PEI/PMo12/Ru(bpy))3}. The grains are homogeneously dispersed in the substrate and have a rather narrow diameter size distribution. [Copyright &y& Elsevier]

A luminescent multilayer film has been fabricated from mixed-addenda polyoxometalate anion [Eu(SiW4Mo7O39)2]13- (EuSiWMo) and polyethyleneimine (PEI) through electrostatic layer-by-layer self-assembly (LBL). The fabrication processes of the film have been monitored by UV-Vis absorption spectra. The results indicated that the composite film was formed by the alternate adsorption of EuSiWMo and PEI, and the layer growth was linear and highly reproducible from layer-to-layer. The elemental composition of the film was obtained from X-ray photoelectron spectrum (XPS). The data of XPS confirmed the presence of the expected elements. The film was smooth and homogeneous as indicated by atomic force microscopy images (AFM). The close-packed nanoclusters of the conglomeration of EuSiWV anions, with a mean grain size of ca. 60 nm, are distributed on the surface uniformly. The mean interface roughness estimated by AFM is about 3.8 nm in an area of 2.0×2.0 μm2. The film exhibited characteristic emission bands of rare-earth ions, consisting with those of the solid sample. In addition, the electrochemical behavior of the film was investigated by cyclic voltammetry, indicating that the electrochemical property of EuSiWMo was fully maintained in the LBL film. [Copyright &y& Elsevier]

A nanosized composite film based on polyoxometalate anion [Eu(SiW10VO39)2]15− (EuSiWV) and polyethyleneimine (PEI) has been synthesized by layer-by-layer (LBL) self-assembly. The components and growth processes of the film have been determined by X-ray photoelectron spectra and ultraviolet–visible absorption spectra. The results showed that the composite film was formed by the alternate adsorption of EuSiWV and PEI, and the deposition process was quantitative and highly reproducible from layer to layer. Atomic force microscopy images indicated that the surface of the film was relatively uniform and smooth. The EuSiWV salt aggregated into nanoclusters with approximately 10 nm mean grain size, distributing on the surface uniformly. The surface roughness was approximately 2.4 nm. Fluorescence properties of the film were consistent with those of the solid sample, exhibiting obvious activity of fluorescence and incarnating the characteristic luminescence of Eu3+. In addition, the electrochemical behavior of the film has also been investigated, demonstrating that the electrochemical property of EuSiW10V was fully maintained in the LBL film. [Copyright &y& Elsevier]

Abstract: Multilayer films based on Keggin-type polyoxometalate (POM) α-[SiW12O40]4− (α-SiW12), α-[PMo12O40]3− (α-PMo12) and cationic chitosan have been fabricated in aqueous solution via the layer-by-layer self-assembly technique (LBL). The resulting films were characterized by UV–Vis spectra, X-ray photoelectron spectra (XPS), atomic force microscopy (AFM) and cyclic voltammetry (CV) measurements. UV–Vis spectra show that the absorbance values at characteristic wavelengths of the multilayer films increase almost linearly with the number of chitosan/POM bilayers, suggesting that the deposition process is regular and highly reproducible from layer to layer. XPS spectra confirm the incorporation of chitosan and POMs into the films. AFM images indicate that the surface of the multilayer films is rather uniform and smooth. The antibacterial activities against Escherichia coli of the LBL films have also been investigated by optical density method. [Copyright &y& Elsevier]

Abstract: An inorganic–organic hybrid polyoxometalate (POM) (Hbpy)4[SiMo12O40] (1) (bpy=2,4-bipyridine), has been prepared and characterized. X-ray diffraction study reveals that compound 1 contains interesting organic double helical chains. The hybrid nanoparticles was used as a solid bulkmodifier to fabricate a three-dimensional chemically modified carbon paste electrode (1-CPE) by direct mixing. The electrochemical behavior and electrocatalysis of 1-CPE has been studied in detail. The results indicate that 1-CPE has a good electrocatalytic activity toward the reduction of nitrite in 1M H2SO4 aqueous solution. 1-CPE shows remarkable stability that can be ascribed to the interactions existed between POM anions and organic double helical bpy chains, which are very important for practical applications in electrode modification. [Copyright &y& Elsevier]

Abstract: A new hydrogen-bonded network featuring bicapped dimerized polyanion, (1) (bpy=4,4′-bipyridine), has been synthesized under hydrothermal conditions. The study of electrochemical property of compound 1 shows it undergoes three two-electron redox processes. [Copyright &y& Elsevier]

Abstract: Two new neutral bicapped bisupporting Keggin-polyoxometalate derivatives: [M(2,2′-bpy)2(H2O)]2[] (M=Co 1, Zn 2; 2,2′-bpy=2,2′-bipyridine), have been synthesized under hydrothermal conditions by directly using H4SiMo12O40 as starting materials. Crystal data for compound 1: C40H36Co2Mo12N8O44SiV2, triclinic, space group , , , , , , , V=1706.3(6)Å3, ; for compound 2, C40H36Mo12N8O44SiV2Zn2, triclinic, space group , , , , , , , V=1709.6(6)Å3, . The studies of the electrochemical property of compounds 1 and 2 exhibit similar redox behavior to the parent [(C4H9)4N]4SiMo12O40, undergoing three two-electron reversible reductions. Variable-temperature magnetic susceptibility measurement of compound 1 demonstrates the presence of antiferromagnetic interactions. [Copyright &y& Elsevier]

Abstract: The solid hybrid material (H3/4pbpy)4[PMo12O40]·1.25H2O (1) (pbpy=5-phenyl-2-(4-pyridinyl)pyridine) has been prepared and characterized. A structural feature of compound 1 is that the polyoxometalate anions exhibit a one-dimensional inorganic double chain-like structure via weak interactions of O…O. The organic moiety exhibits regular packing with offset aromatic–aromatic interactions between the pbpys, leading to a compact supramolecular framework structure to accommodate the inorganic chains. Compound 1 was employed to fabricate the three-dimensional bulk-modified carbon paste electrode (1-CPE) to research on its electrochemistry properties. The results indicate that 1 retained Keggin molybdate anion electrocatalytic activities toward the reduction of chlorate, hydrogen peroxide and nitrite. [Copyright &y& Elsevier]

Abstract: A Keggin polyoxometalate with pendant tricyclic, aromatic entity, formulated as (Hpbpy)5[PW11O39Co(pbpy)]·2H2O (1) (pbpy=5-phenyl-2-(4-pyridinyl)pyridine), was synthesized and characterized by X-ray single crystal structure analysis and temperature-dependent magnetic susceptibility, which represents an unprecedented organic capped-structure. Crystal data: C96H81N12O41PCoW11, triclinic, P-1, a=14.352(3)Å, b=20.467(4)Å, c=21.141(4)Å, α=61.30(3)°, β=75.87(3)°, γ=88.63(3)°, V=5250.5(18)Å3, Z=2. [Copyright &y& Elsevier]

Abstract: A new bicapped Keggin polyoxometalate derivative, [Co(phen)3]2[SiMoVI8MoV4VIV2O42]·H2O (phen=1,10′-phenanthroline), has been synthesized under hydrothermal conditions by using H4SiMo12O40 as starting materials. Two kinds of crystallographic unique supramolecular chains coexisted in the crystal structure. Single crystal X-ray analysis revealed that compound 1 crystallized in the triclinic system, space group , a=11.911(4) Å, b=13.726(0) Å, c=14.892(6) Å, α=105.492(2)°, β=91.358(4)°, γ=97.432(4)°, V=2322.37(8) Å3, Z=1. Other characterizations by elemental analysis, IR, XPS, ESR and TGA analysis were also described in this paper. [Copyright &y& Elsevier]

The first example of one-dimensional organic–inorganic polymetallic coordination polymer based on heptamolybdate anions, formulated (NH4)[Cu(en)2][Na(en)Cu(en)2(H2O)(Mo7O24)] · 4H2O (en = ethylenediamine) (1) has been hydrothermally synthesized and characterized by element analysis, IR, EPR, CV and single crystal X-ray diffraction. The structure of 1 is fabricated by self-assembly of integrated heptamolybdic anions without collapse of primary structure and copper-ethylenediamine(en) coordination groups into one-dimensional zigzag-shaped chains. [Copyright &y& Elsevier]

Abstract: A new inorganic–organic hybrid compound constructed from Keggin-type polyoxometalate and cadmium-organic units, namely, [Cd(Htrz)3]2[SiW12O40]·2H2O (1), [Htrz=1-H-1,2,4-triazole], has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, IR, TG, and UV–vis absorption spectra. In compound 1, each [SiW12O40]4− cluster is modified by six [Cd(Htrz)3]2+ metal–organic fragments, meanwhile, each [Cd(Htrz)3]2+ also connects with three [SiW12O40]4− to built up a binodal (3,6)-connected 2D planar network with the (43)2(46·66·83)-kgd topology. Interestingly, [SiW12O40]4− cluster exhibits a rare coordination mode acting as a hexadentate ligand, in which all of the six terminal oxygen atoms in the equatorial plane are synchronously participated in coordination. The diffuse reflectivity spectrum shows it can be regarded as a wide gap semiconductor. Moreover, the photocatalytic performance shows good photocatalytic activity for the degradation of Rhodamine B. [Copyright &y& Elsevier]