Assembly of a basket-like {Sr ⊂ P₆Mo₁₈O₇₃} cage from 0D dimmer to 2D network and its photo-/electro-catalytic properties

Abstract

A series of basket-like heteropoly blues, formulated as (H4bth)[{Cu(H2O)}2{Sr ⊂ P6MoV2MoVI16O73}]·4H2O (1), {H2bih}3[{FeII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (2), (H2bih)3[{CoII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (3), (H2bih)3[{NiII(H2O)2}{Sr ⊂ P6MoV2MoVI16O73}]·2H2O (4), (H2bih)2(H2bip)[{Zn (H2O)0.5}{Sr ⊂ P6MoV2MoVI16O73}]·5.5H2O (5), (bth = 1,6-bis(triazole)hexane; bih = 1,6-bis(imidazol)hexane; bip = 1,5-bis(imidazol)pentane) have been synthesized hydrothermally and fully characterized. The structural analysis shows that all the compounds contain two electron reduced polyanions [Sr ⊂ P6MoV2MoVI16O73]8− (abbreviated as {P6Mo18O73}), which consists of a tetra vacant γ-Dawson-type{P2Mo14} unit and a “handle”-shaped {P4Mo4} segment encapsulating a Sr2+ cation in the central cavity. Compound 1 is a 6-connected two-dimensional (2D) layer, which represents the first 2D assembly of basket-type polyoxometalates. Compounds 2–4 are isostructural one-dimensional zigzag chains linked by an M(H2O)2 linker (M = iron for 2, cobalt for 3, and nickel for 4). Compound 5 is a dimeric cluster supported by a binuclear {Zn2(H2O)} unit. The optical band gaps of 1–5 reveal their semiconductive natures. The compounds if used as photocatalysts exhibit a universal high efficiency degradation ability for dyes such as methylene blue, Rhodamine B, and Azon phloxine. The lifetime and reaction mechanism of the catalysts were investigated with a series of experiments. The compounds also show good bifunctional electrocatalytic behavior for the oxidation of ascorbic acid (AA) and reduction of nitrite ions.

Diversity of Polyoxometalate‐Based Copper Compounds Obtained from the Same Reaction System

“…Correspondingly, two new anodic peaks appear at E 1/2 = 0.61 and 1.16 V, the former of which is a two‐electron oxidation, whereas the latter is a one‐electron oxidation; both redox processes are ascribed to the oxidation of HNO 2 . The CAT parameter [Equation ] calculated for peaks IV and VI gives a value of 5 × 10 2 % (at 12.3 m m ), which is comparable to that reported in other work …”

Self-assembly of a novel multicomponent polyoxometalate-based tetrahedral supercluster with high catalytic activity for thioether oxidation

“…It's worth noting that these active coordination sites of P 6 Mo 18 are not fully utilized, so only a few simple P 6 Mo 18 -dimerized clusters but no giant P 6 Mo 18 -based polyhedral superclusters have been reported up to now. 21–23 In addition, inspired from the easy substitution of Mo in Keggin and Well–Dawson anions by transition metal ions, we believe that the same situation would also occur in P 6 Mo 18 . This would lead to the reduction of the overall electron cloud density of the basket-like P 6 Mo 18 and promotes the formation of reactive nucleophilic oxygen, 24 thus provide more chances for the construction of novel cluster-based giant superstructures.…”

Various amide-derived ligands induced five octamolybdate-based metal–organic complexes: synthesis, structure, electrochemical sensing and photocatalytic properties

“…39,40 Generally, many POM-based complexes can be considered as feasible photocatalysts for the degradation of organic dyes. 41 In this work, the diffuse reflectance values of all five complexes were measured (Fig. 9a), and the band gaps of complexes 1-5 are 1.94 eV (1), 2.38 eV (2), 2.86 eV (3), 2.93 eV (4) and 2.61 eV (5), respectively, revealing that complexes 1-5 may be promising photocatalysts with semiconductor properties.…”