Zeolitic Polyoxometalate-Based Metal−Organic Frameworks (Z-POMOFs): Computational Evaluation of Hypothetical Polymorphs and the Successful Targeted Synthesis of the Redox-Active Z-POMOF1

Electrochemical properties of the [SiW10O36(M2O2E2)]6− polyoxometalate series (M = Mo(v) or W(v); E = S or O)

New insights about the electrochemical properties of S-containing polyoxometalates. Electrochemical properties of the compounds γ-[SiW₁₀O₃₆(M₂O₂E₂)]⁶⁻ (M = Mo(v) or W(v); E = O²⁻ or S²⁻) in DMF.

Syntheses, structures and properties of three organic–inorganic hybrid polyoxotungstates constructed from {Ni6PW9} building blocks: from isolated clusters to 2-D layers

Three organic–inorganic hybrid POMs were prepared and characterized, exhibiting 0-D to 2-D assemblies made by {Ni₆PW₉} SBUs and organic ligands.

Ln(iii)-Containing polyoxomolybdates based on β-{Mo8O28}: microwave synthesis and optical and magnetic properties

The reactant mother liquor can be obtained by 600 watt microwave irradiation for 15 minutes. Under ultraviolet irradiation, these two compounds can undergo the photochromic process, and the fading process can occur after the ultraviolet irradiation was turned off.

Oriented electron transmission in polyoxometalate-metalloporphyrin organic framework for highly selective electroreduction of CO2

The design of highly stable, selective and efficient electrocatalysts for CO₂ reduction reaction is desirable while largely unmet. In this work, a series of precisely designed polyoxometalate-metalloporphyrin organic frameworks are developed. Noted that the integration of {ε-PMo₈^VMo₄^VIO₄₀Zn₄} cluster and metalloporphyrin endows these polyoxometalate-metalloporphyrin organic frameworks greatly advantages in terms of electron collecting and donating, electron migration and electrocatalytic active component in the CO₂ reduction reaction. Thus-obtained catalysts finally present excellent performances and the mechanisms of catalysis processes are discussed and revealed by density functional theory calculations. Most importantly, Co-PMOF exhibits remarkable faradaic efficiency ( > 94%) over a wide potential range (−0.8 to −1.0 V). Its best faradaic efficiency can reach up to 99% (highest in reported metal-organic frameworks) and it exhibits a high turnover frequency of 1656 h⁻¹ and excellent catalysis stability ( > 36 h).

While CO2 reduction provides a way to remove carbon from the atmosphere, it is challenging to design effective, selective materials for this process. Here, authors construct metal-organic frameworks from polyoxometalates and porphryins to direct electron flow and improve CO2 reduction efficiencies.

Recent advances in isopolyoxotungstates and their derivatives

During the past decade, isopolyoxotungstates (iso-POTs) and their derivatives have been greatly developed due to their unique structures and potential applications in luminescence, magnetism, catalysis etc. This brief review is principally focused on the main research progress on iso-POTs, iso-POT-based transition-metal derivatives, iso-POT-based rare-earth derivatives, iso-POT-based organometallic derivatives and iso-POT-based heterometallic derivatives, and gives a summary of some representative examples of their syntheses, structures and related properties. In addition, an outlook on the future of this area is presented in the final section. We believe that this systematic commentary on iso-POTs and their derivatives will not only disclose a rich set of iso-POT structures, but also reveal a more promising direction for the further functionalization of iso-POTs.

Organometallic functionalized non-classical polyoxometalates: synthesis, characterization and electrochemical properties

Two monomeric non-classical tellurium-containing heteropolymolybdate-supported metal carbonyl derivatives (NH4)5H3{[Te2Mo12(OH)O44][Mn(CO)3]}·18H2O (1) and (NH4)8{[Te2Mo12(OH)O44][Re(CO)3]}·13H2O (2) have been successfully isolated in good yields. Compounds 1 and 2 are the first two examples of metal carbonyl derivatives of heteromolybdate with tellurium as the central atom. These two compounds have been thoroughly characterized by single-crystal X-ray diffraction, elemental analyses, X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and UV-Vis spectroscopy. The electrochemical catalytic activities of 1 and 2 including cyclic voltammetry and catalytic oxidation of nitrite have also been investigated.

Design and synthesis of multifunctional metal-organic zeolites

Metal-organic zeolites (MOZs) are an important branch of metal-organic frameworks (MOFs) and combine the advantages of zeolites and MOFs, such as high surface area and porosity as well as the exceptional stability of zeolites, which would have a significant impact on catalysis chemistry, inorganic chemistry, coordination chemistry, materials science and other areas. In this review, we focus on the recent advances in MOZs with a brief outline of the most prominent examples. In particular, we highlight the basic principles of the design and synthesis approaches toward the construction of MOZs. Obeying the principle of charge matching, tuning tetrahedral metal centers, using enlarged tetrahedral building units as clusters, introducing functional groups into ligands, and combining traditional inorganic TO₄ sites in MOZs enable the final materials with diverse topological structures to exhibit superior performance for various applications, such as gas sorption/separation, catalysis, enantio-selectivity, luminescence, etc.

Incorporating cuprous-halide clusters and lanthanide clusters to construct Heterometallic cluster organic frameworks with luminescence and gas adsorption properties

A series of heterometallic cluster organic frameworks based on cuprous-halide Cu₄I₄ clusters and lanthanide clusters have been successfully synthesized under solvothermal conditions.

A new redox-based and stepwise synthetic strategy lead to an unprecedented mixed-valence Keggin-type tungstovanadophosphate (WVI/VIV) bi-capped by vanadium(VIII)-complexes

A new POM-based V^III-organic coordination compound has been prepared using a redox-based and stepwise synthetic strategy.

A new polyoxovanadate-based metal–organic framework: synthesis, structure and photo-/electro-catalytic properties

A new polyoxovanadate-based metal–organic framework has been synthesized, which exhibits high-performance bifunctional photo-/electro-catalytic properties.

A new 3D POMOF with two channels consisting of Wells–Dawson arsenotungstate and {Cl4Cu10(pz)11} complexes: synthesis, crystal structure, and properties

A new 3D POMOF based on Wells–Dawson arsenotungstate was prepared using a hydrothermal reaction. The POMOF exhibits a novel topological structure, photoluminescence properties, and excellent photocatalytic activity.

A Coordination Network with Ligand-Centered Redox Activity Based on facial-[CrIII (2-mercaptophenolato)3 ]3- Metalloligands

The design of redox-active metal-organic frameworks and coordination networks (CNs), which exhibit metal- and/or ligand-centered redox activity, has recently received increased attention. In this study, the redox-active metalloligand (RML) [Me₄ N]₃ fac-[Cr^III (mp)₃ ] (1) (mp=2-mercaptophenolato) was synthesized and characterized by single-crystal X-ray diffraction analysis, and its reversible ligand-centered one-electron oxidation was examined by cyclic voltammetry and spectroelectrochemical measurements. Since complex 1 contains O/S coordination sites in three directions, complexation with K⁺ ions led to the formation of the two-dimensional honeycomb sheet-structured [K₃ fac-{Cr^III (mp)₃ }(H₂ O)₆ ]_n (2⋅6 H₂ O), which is the first example of a redox-active CN constructed from a RML with o-disubstituted benzene ligands. Herein, we unambiguously demonstrate the ligand-centered redox activity of the RML within the CN 2⋅6 H₂ O in the solid state.

POMzites: A Family of Zeolitic Polyoxometalate Frameworks from a Minimal Building Block Library

We describe why the cyclic heteropolyanion [P8W48O184]40- (abbreviated as {P8W48}) is an ideal building block for the construction of intrinsically porous framework materials by classifying and analyzing >30 coordination polymers incorporating this polyoxometalate (POM) ligand. This analysis shows that the exocyclic coordination of first-row transition metals (TMs) to {P8W48} typically yields frameworks which extend through {W-O-TM-O-W} bridges in one, two, or three dimensions. However, despite the rich structural diversity of such compounds, the coordination of TMs to the {P8W48} ring is poorly understood, and therefore largely unpredictable, and had not until now been present with any structural classification that could allow rational design. Herein, not only do we present a new approach to understand and classify this new class of materials, we also present three {P8W48}-based frameworks which complement those frameworks which have previously been described. These new compounds help us postulate a new taxonomy of these materials. This is possible because the TM coordination sites of the {P8W48} ring are found, once fully mapped, to lead to well-defined classes of connectivity. Together, analysis provides insight into the nature of the building block connectivity within each framework, to facilitate comparisons between related structures, and to fundamentally unite this family of compounds. Hence we have tentatively named these compounds as "POMzites" to reflect the POM-based composition and zeolitic nature of each family member, although crucially, POMzites differ from zeolites in the modular manner of their preparation. As the synthesis of further POMzites is anticipated, the classification system and terminology introduced here will allow new compounds to be categorized and understood in the context of the established materials. A better understanding of TM coordination to the {P8W48} ring may allow the targeted synthesis of new frameworks rather than the reliance on serendipity apparent in current methods.

Functional materials discovery using energy-structure-function maps

Molecular crystals cannot be designed in the same manner as macroscopic objects, because they do not assemble according to simple, intuitive rules. Their structures result from the balance of many weak interactions, rather than from the strong and predictable bonding patterns found in metal-organic frameworks and covalent organic frameworks. Hence, design strategies that assume a topology or other structural blueprint will often fail. Here we combine computational crystal structure prediction and property prediction to build energy-structure-function maps that describe the possible structures and properties that are available to a candidate molecule. Using these maps, we identify a highly porous solid, which has the lowest density reported for a molecular crystal so far. Both the structure of the crystal and its physical properties, such as methane storage capacity and guest-molecule selectivity, are predicted using the molecular structure as the only input. More generally, energy-structure-function maps could be used to guide the experimental discovery of materials with any target function that can be calculated from predicted crystal structures, such as electronic structure or mechanical properties.

Electrochemical and diffuse reflectance study on tetrahedral ε-Keggin-based metal–organic frameworks

Two polymolybdate-based metal–organic frameworks composed of Zn-ε-Keggin nodes and semi-rigid organic linkers were successfully synthesized. The electrochemical behaviors of these two compounds were studied, as well as their diffuse reflectance performance.

A novel 3D POMOF based on Wells–Dawson arsenomolybdates with excellent photocatalytic and lithium-ion battery performance

A novel 3D POMOF based on Wells–Dawson arsenomolybdates exhibits fluorescence property and efficient and stable photocatalytic activity for MB and RhB under UV irradiation and has also been evaluated as the anode material for LIBs.

Construction of (3,6)-connected polyoxometalate-based metal–organic frameworks (POMOFs) from triangular carboxylate and dimerized Zn4-ε-Keggin

The methodology of extension of reduced transition metal-grafted ε-Keggin polyoxoanions with two types of terphenyl-based tricarboxylates was used to isolate two (3,6)-connected 3D POMOFs.

Perspectives on metal–organic frameworks with intrinsic electrocatalytic activity

This highlight article focuses on the rapidly emerging area of electrocatalytic metal–organic frameworks (MOFs) with a particular emphasis on those systems displaying intrinsic activity.

A highly stable polyoxometalate-based metal–organic framework with an ABW zeolite-like structure

A novel polyoxometalate-based metal–organic framework (POMOF) with an ABW network, NENU-601, was synthesized in situ.

Anderson-like alkoxo-polyoxovanadate clusters serving as unprecedented second building units to construct metal-organic polyhedra

Unprecedented Anderson-like alkoxo-polyoxovanadate [V6O6(OCH3)9(μ6-SO4)(COO)3](2-) polyanions can serve as 3-connected second building units (SBUs) that assemble with dicarboxylate or tricarboxylate ligands to form a new family of metal organic tetrahedrons of V4E6 and V4F4 type (V = vertex, E = edge, and F = face). To our knowledge, this alkoxo-polyoxovanadate-based SBU is the first ever reported.

New crystalline complex metal oxides created by unit-synthesis and their catalysis based on porous and redox properties

The development of new complex metal oxides having structural complexity suitable for solid-state catalysis is of great importance in fundamental catalysis research and practical applications. However, examples of these materials are rare. Herein, we report two types of crystalline complex metal oxides with new structures and their catalytic properties. The first one is an all-inorganic ε-Keggin polyoxometalate-based material with intrinsic microporosity. The framework of the material is formed by the assembly of ε-Keggin polyoxomolybdate units with metal ion linkers in a diamondoid topology. The micropores of the material can be opened without change of the structures, and the material adsorbs small molecules. This material has both redox properties and acidity and can be applied to O₂ adsorption, selective oxidation of methacrolein, and hydrolysis of cellobiose. The other material is a crystalline metal oxide based on molecular nanowires. The hexagonal POM units stack along the c axis to form prismatic clusters as molecular wires. The molecular wires further assemble in a hexagonal fashion to form the crystals, and NH₄⁺ and water are present in between the molecular wires. The material is active as an acid catalyst for cellobiose conversion.

A multifunctional lanthanide metal–organic framework supported by Keggin type polyoxometalates

An unusual multifunctional POM@MOF neodymium metal–organic framework with 1D nanotubular channels incorporating Keggin type [SiWV3WVI9O₃₈]³⁻ polyoxometalates was successfully synthesized.

Comparing gas separation performance between all known zeolites and their zeolitic imidazolate framework counterparts

Candidate structures for environmental and industrial gas separations. No correlation between zeolites and their respective Zeolitic Imidazolate framework counterparts.

New organic–inorganic hybrid compounds constructed from polyoxometalates and transition metal mixed-organic-ligand complexes

Five compounds constructed from different polyoxoanions and metal mixed-organic complexes of carboxylates and nitrogen-containing ligands have been synthesized and characterized.

Research progress on polyoxometalate-based transition-metal–rare-earth heterometallic derived materials: synthetic strategies, structural overview and functional applications

This review summarizes the structural types of reported polyoxometalate-based transition-metal–rare-earth heterometallic derived materials (PTRHDMs) together with synthetic strategies, structural motifs and relevant functional applications.

A series of organic–inorganic hybrid materials consisting of flexible organic amine modified polyoxomolybdates: synthesis, structures and properties

A series of hybrid materials consisting of Tris[(2-pyridyl)methyl]amine modified polyoxomolybdates were obtained and some complexes have efficient photocatalytic activities to degrade pararosaniline hydrochloride dye molecules.

Polyoxometalate-based supramolecular architecture constructed from a purely inorganic 1D chain and a metal–organic layer with efficient catalytic activity

A new polyrotaxane structure constructed from a pure inorganic polyoxometalate-based 1D chain, exhibited efficient catalytic activity for desulfurization and electrocatalytic redox activity.

Structure and Solution Speciation of U(IV) Linked Phosphomolybdate (Mo(V)) Clusters

Crystals of [NaU(Mo6P4O31H7)2]·5Na·(H2O)n (NaUMo6) have been synthesized by slow evaporation of an aqueous mixture containing uranyl nitrate, sodium molybdate, phosphoric acid, and sodium dithionate. Single crystal diffraction of NaUMo6 reveals the assembly of {Mo6P4} clusters linked into one-dimensional chains with alternating Na(+) and U(4+) cations. To our knowledge, NaUMo6 is a unique example of Mo(5+) based polyoxometalate associated with actinides. With the use of similar synthesis conditions but without uranium in the aqueous solution, [Na(Mo6P4O31H10)2]·5Na·(H2PO4)·(H2O)n (NaMo6) is obtained. NaMo6 is a sandwich type cluster which is built on the assemblage of two {Mo6P4} units linked by one sodium cation. Using small-angle X-ray scattering techniques and aqueous electrolyte based dissolution strategies, we can accurately observe chains of [UNa(Mo6P4O31H7)2]n(5n), where n = 7 is the dominant soluble specie. Likewise, the dimeric form of [Na(Mo6P4O31H10)2](5-) dominates the aqueous solution, revealing the structural units observed in the crystal structure are also stable in solution, under appropriate dissolution conditions.