Hydrothermal syntheses, crystal structures and characterization of new vanadoborates: The novel decorated cage cluster [V6B22O44(OH)10]

Heptanuclear Cadmium Borovanadate Containing a Sandwich-Type Anionic Partial Structure {B20V12} as a Heterogeneous Photocatalyst for the Reduction of CO2 into CH4

The novel heptanuclear cadmium borovanadate [Cd(en)3]{[Cd(H2O)(en)]6[B20V12O60(OH)2]}·8H2O (en = ethylenediamine) has been prepared under hydrothermal condition. It exhibits a 2D layered architecture that is built up from the [Cd(H2O)(en)]2+ coordination cations and new sandwich-type borovanadate anions [B20V12O60(OH)2]14- constructed by BO3, BO4, BO3(OH), and VO5 units. It features the first heptanuclear cadmium borovanadate containing the single valence of V4+ cations and unique B/V ratio (B/V = 20/12). Its thermal, magnetic, XPS, and optical properties have been systematically studied. The Eg (2.60 eV), EVB (1.69 eV), and ECB (-0.91 eV) were well determined by the UV-vis diffuse reflectance spectrum, UPS curve, and the formula ECB = EVB - Eg, respectively. The photocatalytic experiments revealed that the borovanadate could be selected as an effective and stable heterogeneous catalyst for the reduction of CO2 to CH4 by means of visible light (the amount for CH4 gas could reach 50.57 μmol·g-1·h-1 when the reaction time was 3 h). The recycling experiment and photocatalytic mechanism were also well investigated and established in detail.

Construction of a unique 2-D layered vanadoborate with water-assisted proton conductivity

In the present work, a new two-dimensional layered vanadoborate Na4[V12B18O54(OH)6(H2O)]•(H2en)4•2(OH)•3H2O (1, en = ethylenediamine), based on a [V12B18O54(OH)6(H2O)]10- cluster unit, was hydrothermally obtained and characterized. In the structure, the clusters...

Vanadoborates: cluster-based architectures, preparation and properties

The different connections of [VO_x] (x = 4, 5, 6) and [AO_x] (A = B, x = 3, 4; A = P, x = 4) polyhedral units ultimately result in a fascinating variety of vanadoborate anionic clusters.

Study on the source of magnetic properties of three novel boratopolyoxovanadates via two-dimensional infrared correlation spectroscopy

Three novel polyoxovanadoborates namely [V₁₂B₁₈O₄₆(OH)₁₄(H₂O)_0.75]·20.5H₂O 1, Na₂[V₁₂B₁₈O₄₈(OH)₁₂(H₂O)_0.5]·26.5H₂O 2 and Cd_0.5{[Na(H₂O)₂]2[Na(H₂O)]₂[Na(H₂O)₃]2V₁₂B₁₈O₅₃(OH)₇(H₂O)_0.5}·11H₂O 3 have been hydrothermally synthesized and structurally characterized. The boratopolyoxovanadate cage [V₁₂B₁₈O₆₀] backbones in 1-3 are constructed by the combination of two hexameric oxovanadate units [V₆O₉] and one puckered [B₁₈O₄₂] ring via sharing O atoms. All three compounds were obtained under alkaline conditions, and the cluster anions were all [V₁₂B₁₈O₆₀]. But the cations were different, it is inferred that the protonation of the three compound cluster ions is different, respectively [V₁₂B₁₈O₄₆(OH)₁₄(H₂O)_0.75] in 1, [V₁₂B₁₈O₄₈(OH)₁₂(H₂O)_0.5]^2- in 2 and [V₁₂B₁₈O₅₃(OH)₇(H₂O)_0.5]^7- in 3. The V oxidation states ratio of V^IV to V^V were 2:1 confirmed by valence bond calculation and XPS. We studied the magnetic properties of three compounds by two methods: The variable temperature magnetic susceptibility and the 2D IR COS under magnetic perturbation. From the 2D IR COS under magnetic perturbation map, it is showed that all three: (1) the presence of V^IV. (2) Certain quasi-aromaticity from B₃O₃ six-membered ring. (3) The difference of protonation and the charge of the cluster anions. This work enriches the theory of two-dimensional correlation spectroscopy and also provides a new approach to the study of magnetic materials.

A New 3-D Open-Framework Zinc Borovanadate with Catalytic Potentials in α-Phenethyl Alcohol Oxidation

A novel 3-D open-framework zinc borovanadate [Zn₆(en)₃][(VIVO)₆(VVO)₆O₆(B18O36(OH)₆)·(H₂O)]₂·14H₂O (1, en = ethylenediamine) was hydrothermally obtained and structurally characterized. The framework was built from [V12B18O54(OH)₆(H₂O)]10- polyanion clusters bridged by Zn(en) complex fragments. The compound not only possessed a three-dimensional open-framework structure with unique plane-shaped channels, but also exhibited excellent catalytic activities for the oxidation of α-phenethyl alcohol.

The origin of the electronic transitions of mixed valence polyoxovanadoborates [V12B18O60]: from an experimental to a theoretical understanding

New insights in the electronic properties of mixed-valence polyoxovanadoborate clusters.

Analogies between Vanadoborates and Planar Aromatic Hydrocarbons: A High-Spin Analogue of Aromaticity

The vanadium-vanadium interactions in the polygonal aggregates of d¹ vanadium(IV) atoms, with a total of 4k + 2 vanadium electrons (k an integer) imbedded in an electronically inactive borate matrix in certain vanadoborate structures are analogous to the ring carbon-carbon interactions in diamagnetic planar cyclic hydrocarbons. They thus represent a high-spin analogue of aromaticity. Thus, the vanadoborate anion [V₆B₂₀O₅₀H₈]⁸⁻ with six V(IV) electrons (i.e., 4k + 2 for k = 1) contains a macrohexagon of d¹ V(IV) atoms with four unpaired electrons. This high-spin system is related to the low-spin aromaticity in the diamagnetic benzene having six π electrons. Similarly, the vanadoborate anion [V₁₀B₂₈O₇₄H₈]¹⁶⁻ with ten V(IV) electrons (i.e., 4k + 2 for k = 2) contains a macrodecagon of d¹ V(IV) atoms with eight unpaired electrons. Again, this high-spin system is related to the aromaticity in the diamagnetic 1,6-methanol[10]annulene, having ten π electrons.

Proton conduction in a new 3-D open-framework vanadoborate with an abundant hydrogen bond system

A 3-D hydrogen bond-enriched vanadoborate was successfully synthesized under hydrothermal conditions and it exhibited good proton conductivity.

A new 3-D open-framework Li-rich vanadoborate and its high ionic conductivity after transforming into glasses

A Li-rich vanadoborate was transformed into its glassy phase at 220 °C, which then exhibits high ionic conductivity.

A 3D cadmium–vanadium bimetallic framework with luminescence properties

Luminescent properties of a novel cadmium–vanadium bimetallic 3D framework possessing a pillared-layer.

Employing a new 12-connected topological open-framework copper borovanadate as an effective heterogeneous catalyst for oxidation of benzyl-alkanes

A new 12-connected topological open-framework copper borovanadate with a unique B/V ratio (20/12) and a -B3O7(OH)-Na(μ-OH)[B(OH)2]-B3O7(OH)- connection mode has been hydrothermally obtained and characterized. It not only features the first 3-D copper(II) borovanadate which possesses the largest ratio of TM(2+) and borovanadate anion, but also displays highly catalytic activities for the oxidation of benzyl-alkanes.

A new 3-D open-framework cadmium borovanadate with plane-shaped channels and high catalytic activity for the oxidation of cyclohexanol

A new 3-D open-framework cadmium borovanadate with 6-connected topology was hydrothermally obtained and structurally characterized. It not only features new cadmium(II) borovanadate which possesses an open-framework structure with unique plane-shaped channels, but also exhibits interesting absorption properties and high catalytic activities for the oxidation of cyclohexanol.

Layered V-B-O polyoxometalate nets linked by diethylenetriamine complexes with dangling amine groups

Two layered V-B-O contained polyoxometalate (POM) net structures, denoted as SUT-12 and SUT-13, are reported here. SUT-12 was synthesized by the boric acid flux method, and it represents the first 2D structure constructed from the V6B20 vanadoborate cluster. SUT-13 was synthesized by the hydrothermal method and constructed from V12B6P12 vanadium borophosphate clusters. In both structures, the vanadoborate or vanadium borophosphate clusters were linked through in situ formed Zn(DETA)2 or Cu(DETA)2 complexes. Surprisingly, for all DETA molecules in the two metal complexes, there is one dangling amine group when it is coordinated to the metal. The phenomenon of the dangling amine group feature is abnormal and the Cu(DETA)2 complexes in SUT-13 were taken as an example and studied by the density functional theory (DFT) calculations in order to understand this unusual feature.