Tailoring the Coordination Microenvironment of Polymolybdate within a Metal-Organic Coordination System for Enhanced Capacitive Activity

The design of a low-cost and efficient electrode material is crucial for electrochemical energy storage. Effectual utilization of polymolybdate as an electrode material for a supercapacitor is promising. Meanwhile, the coordination microenvironments of polymolybdate sho potential effects on its performance. Herein, we designed and synthesized four polymolybdate-based metal-organic complexes using a structure design strategy. Their structures were characterized and analyzed using single crystallographic data. The theoretical calculations revealed that the coordination microenvironments of polymolybdate play a vital role in the hydrogen ions migration. High H adsorption capacity can obviously boost the electrochemical activity. The 1-based glassy carbon electrode showed the highest specific capacitance value of 1739.4 F·g-1 at the current density of 1 A·g-1. Meanwhile, the carbon cloth-based electrode fabricated by complex 1 (1/CC) also displayed a high capacitance performance. A hybrid supercapacitor was assembled using the 1/CC electrodes and showed a high energy density of 29.0 Wh kg-1 at the power density of 0.80 kW kg-1.

Anderson-type polyoxometalates: from structures to functions

Anderson-type polyoxometalates (POMs) are one of the most important groups of the POM family. In the past decade, the functionalization of Anderson-type POMs has achieved significant progress and these materials have already shown unique charm in catalysis, molecular devices, energy materials, and inorganic biochemical drugs. In particular, their highly flexible topological structure and diverse functionalization methods make them the most convenient and universal platforms for rational design and controllable synthesis. This review provides a deep discussion on the recent progress in the synthetic methodology, structural exploration, and promising applications of Anderson-type POMs. It also summarizes the latest research directions and provides future prospects.

Polyoxometalate-based metal–organic frameworks for heterogeneous catalysis

POM-based MOFs simultaneously possessing the virtues of POMs and MOFs exhibit excellent heterogeneous catalytic properties.

Involvement of various anions in tuning the structure of silver(i) coordination polymers based on a S-donor ligand: syntheses, crystal structure and uptake properties

Ag(i) coordination polymers based on a S-donor ligand containing of various anions were synthesized and characterized. Also, the absorption potential of the polymers was examined by the NH3 and H2S gases.

Various Anderson-type polyoxometalate-based metal–organic complexes induced by diverse solvents: assembly, structures and selective adsorption for organic dyes

A series of Anderson-type polyoxometalates (POMs)-based metal–organic complexes with different structures have been synthesized, they show excellent dye adsorption and chromatographic separation in a short time.

How Does the Redox State of Polyoxovanadates Influence the Collective Behavior in Solution? A Case Study with [I@V18O42] q- ( q = 3, 5, 7, 11, and 13)

A series of stable reduction-oxidation states of the cagelike [I@V^IV _xV^V_{18- x}O₄₂]^{5- x} polyoxovanadate (POV) with x = 8, 10, 12, 16, and 18 were studied with density functional theory and molecular dynamics to gain insight into the structural and electron distribution characteristics of these metal-oxo clusters and to analyze the charge/redox-dependent assemblage processes in water and acetonitrile (MeCN) solutions. The calculations show that the interplay between the POV redox state (molecular charge) and the solvent polarity, countercation size, and hydrophilicity (or hydrophobicity) controls the POV agglomeration phenomena, which substantially differ between aqueous and MeCN media. In MeCN, agglomeration is more pronounced for intermediate-charged POVs, whereas in water, the lowest-charged POVs and organic countercations tend to agglomerate into a microphase. Tests made on wet MeCN show diminished agglomeration with respect to pure MeCN. Simulations with alkali countercations in water show that only the highest-charged POV can form agglomerates. The herein presented theoretical investigation aims to support experimental studies of POVs in the field of functional nanomaterials and surfaces, where controlled molecular deposition from the liquid phase onto solid substrates requires knowledge about the features of these metal-oxo clusters in discrete solutions.

Evans–Showell-type polyoxometalate-based metal–organic complexes with novel 3D structures constructed from flexible bis-pyrazine–bis-amide ligands and copper metals: syntheses, structures, and fluorescence and catalytic properties

Two 3D Evans–Showell-type POM-based copper–bis-pyrazine–bis-amide complexes show good heterogeneous catalytic activity for the oxidation of benzyl alcohol.

Ligand-Controlled Assembly of Heteropolyoxomolybdates from Plenary Keggin Germanomolybdates and Cu-Ln Heterometallic Units

By virtue of combining an in-situ assembly process with a stepwise synthesis in conventional aqueous solution, two series of unique organic-inorganic hybrid heteropolyoxomolybdates were constructed from plenary Keggin germanomolybdates and Cu-Ln heterometallic units and fully characterized: [H₂ INA]₂ H₈ [LnCu(INA)₄ (H₂ O)₆ ]₂ [α-GeMo₁₂ O₄₀ ]₃ ⋅52 H₂ O (Ln=La³⁺ (1), Ce³⁺ (2), Pr³⁺ (3), Nd³⁺ (4), Sm³⁺ (5), Eu³⁺ (6); HINA=isonicotinic acid) and (NH₄ )[Cu(PA)₂ ][Cu(PA)₂ Ln(H₂ O)₈ ][α-GeMo₁₂ O₄₀ ]⋅10 H₂ O (Ln=Nd³⁺ (7), Sm³⁺ (8), Eu³⁺ (9); HPA=picolinic acid). The most remarkable structural characteristic of compounds 1-6 was that their molecular units were defined by three discrete plenary Keggin [α-GeMo₁₂ O₄₀ ]^4- polyoxoanions and two organic-inorganic hybrid heterometallic [LnCu(INA)₄ (H₂ O)₆ ]⁺ moieties, whereas compounds 7-9 exhibited a nice-looking 1D chain-like structure that was built from plenary [α-GeMo₁₂ O₄₀ ]^4- polyoxoanions, pendent [Cu(PA)₂ ] complexes, and bridging {[Cu(PA)₂ ][Ln(H₂ O)₈ ]}³⁺ heterometallic groups. Notably, two different pyridine carboxylic acid ligands led to the discrepancy between the two structure types. To the best of our knowledge, compounds 1-9 constitute the first examples of plenary Keggin heterometallic germanomolybdates that include Cu-Ln-organic subunits. Further studies revealed that compounds 3 and 8 exhibited fast adsorption capacity for cationic dyes methylene blue (MB) and rhodamine B (RhB) in water. Moreover, compounds 3 and 8 could quickly and selectively adsorb MB from a mixture of MB/methyl orange (MO) or MB/azophloxine (Apo).

One-dimensional networks formed via the self-assembly of anthracenedibenzoic acid with zinc(II)

Self-assembly of metal-organic coordination polymers occurs because of enthalpically favorable interactions. In the case of the bulky 4,4'-(anthracene-9,10-diyl)dibenzoic acid ligand (abdH₂), we demonstrate that the presence of numerous π-π and C-H...π interactions outweigh the formation of saturated coordination complexes with zinc, leading to the formation of a dimethylformamide (DMF) solvate, namely 4,4'-(anthracene-9,10-diyl)dibenzoic acid dimethylformamide disolvate, C₂₈H₁₈O₄·2C₃H₇NO or [(abdH₂)(DMF)₂], at low concentrations of zinc. Meanwhile, at higher zinc concentrations, the abdH₂ ligand gives rise to the nonporous one-dimensional coordination polymer catena-poly[[bis(dimethylformamide-κO)zinc(II)]-μ-4,4'-(anthracene-9,10-diyl)dibenzoato-κ²O:O'], [Zn(C₂₈H₁₆O₄)(C₃H₇NO)₂]_n or [Zn(abd)(DMF)₂]_n, when assembled in dimethylformamide, while a related compound is observed when N,N-dimethylacetamide (DMA) is used as the solvent, namely catena-poly[[[bis(N,N-dimethylacetamide-κO)zinc(II)]-μ-4,4'-(anthracene-9,10-diyl)dibenzoato-κ²O:O'] N,N-dimethylacetamide monosolvate], {[Zn(C₂₈H₁₆O₄)(C₄H₉NO)₂]·C₄H₉NO}_n or {[Zn(abd)(DMA)₂]·DMA}_n. Attempts to use other amide-based solvents did not give rise to any other assembled structures.

Dicarboxylate-induced structural diversity of luminescent ZnII/CdII coordination polymers derived from V-shaped bis-benzimidazole

Six Zn^II/Cd^II CPs (1–6), derived from V-shaped bbib and dicarboxylates, have been synthesized; complex 2 is a good bifunctional chemosensor for the detection of Fe³⁺ and MnO₄⁻.