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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]

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 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 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]

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]

The design of a low-cost, highly efficient and durable electrocatalyst is very important to accelerate the energy conversion efficiency of the electrochemical process. Herein, a simple hydrothermal synthesis of the heterostructure of Wells-Dawson polyoxometalate and zinc iron layered double hydroxide nanosheet is presented for the first time on Ni-foam (ZnFe LDH-P 2 Mo 18 /NF). The electrocatalytic activity of ZnFe LDH-P 2 Mo 18 /NF shows significantly low overpotentials of 275, 330 mV and 273, 367 mV for OER and HER to acquire a current density of 20, 50 mA cm−2 respectively. Additionally, the electrolyzer composed of ZnFe LDH-P 2 Mo 18 /NF cathode and anode shows an attractive voltage of 1.54 V to carry 10 mA cm−2. The better electrochemical performance of the ZnFe LDH-P 2 Mo 18 /NF is ascribed to the variation of electronic and chemical features, growth of electrochemically active surface area/sites because of the construction of heterointerface of Wells-Dawson polyoxometalate and zinc iron LDH. These results further demonstrate the benefits of heterointerface engineering for efficient electrolysis. This study presents a novel hybrid of zinc-iron layered double hydroxide and Dawson polyoxometallate (ZnFe LDH-P 2 Mo 18 /NF) for electrocatalytic water splitting. Notably, ZnFe LDH-P 2 Mo 18 /NF reveals excellent electrocatalytic performance with a large number of electroactive sites, extremely low overpotential, and high durability throughout the water splitting process. [Display omitted] • ZnFe LDH-P 2 Mo 18 hybrid is reported first time for overall water splitting. • ZnFe LDH-P 2 Mo 18 hybrid delivers extraordinary performance for OER and HER. • The high structural integrity and ultralong durability is maintained by the hybrid. [ABSTRACT FROM AUTHOR]