Synthesis, crystal structure and two-dimensional infrared correlation spectroscopy of a layer-like transition metal (TM)-oxalate templated polyoxovanadium borate

Two-dimensional correlation infrared spectroscopy study on vanadoborate anionic skeleton regulated by countercations

Two novel vanadoborate compounds, [Cu(en)2]3[Li(H2O)]4[Li(H2O)3]2[V12B18O50(OH)10(H2O)]2·33.5H2O (1) and (H2en)4[Li(H2O)]4[V12B18O55(OH)5(H2O)]·14H2O (2), were synthesized via hydrothermal synthesis under identical conditions except for temperature. Structural analysis revealed that although both contain [V12B18O60]n- cluster anion, the different countercations potentially lead to variations in the [V12B18O60]n- cluster anion skeletons. In compound 1, the V4+/V5+ ratio was 10:2; while in compound 2 the ratio was 11:1. It is speculated that different countercations may influence the valence states of cluster anions. In this study, quantum chemical calculations revealed that the aromaticity and activity of the two compounds were different, and two-dimensional correlation infrared spectroscopy (2D-COS-IR) under magnetic perturbation confirmed that distinct response peaks of functional group vibrations to the magnetic field due to the different V4+/V5+ ratios and aromaticity of the two compounds. An electrochemical analysis revealed that compound 2 exhibits higher electrocatalytic activity. The results of quantum chemical calculations are aligned not only with the changes in the 2D-COS-IR spectra but also with the conclusions obtained from experiments on electrochemical properties. Overall, this work proposes a novel strategy for interpreting the alteration of vanadoborate anionic skeleton due to the introduction of different countercations by combining 2D-COS-IR with quantum chemical calculations.

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.

Effective photocatalytic and bifunctional electrocatalytic materials based on Keggin arsenomolybdates and different transition metal capped assemblies

V, Co, and Cu were introduced into {AsMo₁₂} system to build three Keggin derivatives with different caps, which show excellent photocatalytic activity and bifunctional electrocatalytic behavior.

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.

Two unusual 3D honeycomb networks based on Wells–Dawson arsenomolybdates with d10 transition-metal-pyrazole connectors

Two unusual 3D honeycomb networks based on Wells–Dawson arsenomolybdates were first reported, which have highly efficient catalytic ability for the degradation of organic dyes under UV irradiation and obvious electrocatalytic activities for the reduction of H₂O₂.

M3V2B10O23 (M = Ca, Sr): two new vanadoborates with [V2B10O23]∞ double layers

Ca₃V₂B₁₀O₂₃ and Sr₃V₂B₁₀O₂₃ are isostructural and their main frameworks are novel “infinite” 2D [V₂B₁₀O₂₃]_∞ double layers which composed of an [B₅O₉]_∞ infinite layer and VO₄ tetrahedra.

Crystal lattice effect on the quenching of the intracluster magnetic interaction in [V12B18O60H6]10− polyoxometalate

Quenching effect of the intracluster antiferromagnetic coupling by alkaline ions of the crystalline packing.

Synthesis and structure of QD-6: a novel aluminoborate constructed from unprecedented [B@Al6O24] and polyborate clusters

A novel aluminoborate (NH(4))(6)[C(5)NH(12)](6)[Al(12)B(65)O(105)(OH)(33)]·(H(2)O)(15) (QD-6), has been synthesized under mild hydrothermal conditions and characterized by IR, elemental analysis, TGA, powder and single-crystal X-ray diffractions. This compound crystallizes in the rhombohedral space group R3 (No. 148) with the lattice constants a = 23.7421(2) Å, c = 24.7699(3) Å, V = 12091.9(2) Å(3), and Z = 3. QD-6 consists of two unprecedented aluminoborate clusters, [Al(6)B(34)O(54)(OH)(18)](6-) and [Al(6)B(31)O(51)(OH)(15)](6-), which are built from the same hexagon-like [B@Al(6)O(24)] clusters and [B(11)O(17)(OH)(6)] or [B(10)O(16)(OH)(5)] polyborates.