Polyoxometalate based open-frameworks (POM-OFs)

Miras, Haralampos N.; Vilà‐Nadal, Laia; Cronin, Leroy

doi:10.1039/c4cs00097h

Cited by 393 publications

(257 citation statements)

References 117 publications

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“…There are seven types (OA-OG in Figure 3) of possible protonation sites, taking account of the D2h symmetry. The solution-state 17 O NMR spectra of [V10O28] 6− (enriched by the addition of H2 17 O) show an up-field shift of the 17 O NMR signals assignable to OB and OC upon acidification with HCl [71,74]. It has been reported that the protonation of oxygen atoms in POMs [38,55,56].…”

Section: Isopolyoxometalatesmentioning

confidence: 99%

“…Protons of crystalline H3PW12O40·6H2O are present as the hydrated species, H5O2 + , each of which links four neighboring POMs by hydrogen bonding to the terminal W-O oxygen atoms [21]. For anhydrous H3PW12O40, the protons have been reported to be attached to the most basic bridging oxygen atoms based on infrared (IR) and 17 O NMR spectroscopy results [21]. Himeno and co-workers reported that the potential difference between the first one-and two-electron redox waves of cyclic voltammograms served as a useful criterion for the basicity of Keggin anions [85,86] …”

Section: Heteropolyoxometalatesmentioning

confidence: 99%

“…Isopolyoxometalates are often utilized as photocatalysts and building units for the synthesis of POM-based functional assemblies [12][13][14]17,35]. In addition, their basic properties have been extensively studied due to their simple compositions and structures.…”

Section: Isopolyoxometalatesmentioning

confidence: 99%

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Base Catalysis by Mono- and Polyoxometalates

Kamata

Sugahara

2017

Catalysts

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Abstract:In sharp contrast with acid-, photo-, and oxidation-catalysis by polyoxometalates, base catalysis by polyoxometalates has scarcely been investigated. The use of polyoxometalates as base catalysts have very recently received much attention and has been extensively investigated. Numerous mono-and polyoxometalate base catalyst systems effective for the chemical fixation of CO 2 , cyanosilylation of carbonyl compounds, and C-C bond forming reactions have been developed. Mono-and polyoxometalate base catalysts are classified into four main groups with respect to their structures: (a) monomeric metalates; (b) isopolyoxometalates; (c) heteropolyoxometalates; and (d) transition-metal-substituted polyoxometalates. This review article focuses on the relationship among the molecular structures, the basic properties, and the unique base catalysis of polyoxometalates on the basis of groups (a)-(d). In addition, reaction mechanisms including the specific activation of substrates and/or reagents such as the abstraction of protons, nucleophilic action toward substrates, and bifunctional action in combination with metal catalysts are comprehensively summarized.

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Section: Isopolyoxometalatesmentioning

confidence: 99%

Section: Heteropolyoxometalatesmentioning

confidence: 99%

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Base Catalysis by Mono- and Polyoxometalates

Kamata

Sugahara

2017

Catalysts

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“…Their formation is mainly based on the appropriate charge to ionic radius ratio and charge density which: (i) prohibits infinite polymerization; (ii) promotes formation of π-bonds with the O 2− ligands; (iii) exhibits flexible and various coordination geometries. In the past decades, the properties of POMs have been extensively investigated due to a wide range of composition, sizes, rich redox chemistry, charge distribution and photochemistry to fulfill specific requirements in a variety of applications, including functional materials in catalysis, molecular electronics, magnetism, materials science and medicine [28][29][30][31]. Based on the above observations, various groups reported their efforts to design POM-based heterogeneous catalytic systems for the promotion of specific reactions.…”

Section: Pom-ldh Composite Materialsmentioning

confidence: 99%

Polyoxometalate (POM)-Layered Double Hydroxides (LDH) Composite Materials: Design and Catalytic Applications

Miras

Song

2017

Catalysts

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Layered double hydroxides (LDHs) are an important large class of two-dimensional (2D) anionic lamellar materials that possess flexible modular structure, facile exchangeability of inter-lamellar guest anions and uniform distribution of metal cations in the layer. Owing to the modular accessible gallery and unique inter-lamellar chemical environment, polyoxometalates (POMs) intercalated with LDHs has shown a vast array of physical properties with applications in environment, energy, catalysis, etc. Here we describe how polyoxometalate clusters can be used as building components for the construction of systems with important catalytic properties. This review article mainly focuses on the discussion of new synthetic approaches developed recently that allow the incorporation of the element of design in the construction of a fundamentally new class of materials with pre-defined functionalities in catalytic applications. Introducing the element of design and taking control over the finally observed functionality we demonstrate the unique opportunity for engineering materials with modular properties for specific catalytic applications.Keywords: layered double hydroxides; polyoxometalates; intercalated materials Layered Double Hydroxides (LDHs)-Intro BackgroundLayered double hydroxides (LDHs) or hydrotalcite-like compounds are a large family of two-dimensional (2D) anionic clay materials made up of positively charged brucite-like layers with an interlayer region containing charge compensating anions and solvation molecules, which can be represented by the general formula -4]. As shown in Figure 1 and generally in the range of 0.20-0.33, which occupy the space between the layers compensating for the positive charge and inducing stability in the overall structure [5,6]. The M II /M III -based edge shared octahedra are used to construct 2D infinite sheets, whereas hydroxyl groups are organized on the vertices of the octahedra with the hydrogen atoms pointing toward the interlayer region, as a consequence forming a complex network of hydrogen bonds with the interlayer anions and water molecules [1,[7][8][9][10]. LDH-based materials are very attractive systems due to their robust structure,

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“…The interplay of supramolecular interactions (through hydrogen bonds, van der Waals forces), as well as reactivity between POM clusters and transition metals or metal complexes, can lead to the formation of extended networks of coordinatively linked 1D chains, 2D sheets and 3D compounds. As shown in the figure below, the POM clusters can be linked through transitional metals (TM) via grafted organic units, directly through transition metals, through organic linkers and through organic linkers via transition metals ( Figure 8) [50]. POM-OFs are porous materials with interesting structural flexibility, stability and interesting physical properties.…”

Section: Pom-ofsmentioning

confidence: 99%

Self-Assembly in Polyoxometalate and Metal Coordination-Based Systems: Synthetic Approaches and Developments

et al. 2018

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Abstract:Utilizing new experimental approaches and gradual understanding of the underlying chemical processes has led to advances in the self-assembly of inorganic and metal-organic compounds at a very fast pace over the last decades. Exploitation of unveiled information originating from initial experimental observations has sparked the development of new families of compounds with unique structural characteristics and functionalities. The main source of inspiration for numerous research groups originated from the implementation of the design element along with the discovery of new chemical components which can self-assemble into complex structures with wide range of sizes, topologies and functionalities. Not only do self-assembled inorganic and metal-organic chemical systems belong to families of compounds with configurable structures, but also have a vast array of physical properties which reflect the chemical information stored in the various "modular" molecular subunits. The purpose of this short review article is not the exhaustive discussion of the broad field of inorganic and metal-organic chemical systems, but the discussion of some representative examples from each category which demonstrate the implementation of new synthetic approaches and design principles.

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Polyoxometalate based open-frameworks (POM-OFs)

Cited by 393 publications

References 117 publications

Base Catalysis by Mono- and Polyoxometalates

Base Catalysis by Mono- and Polyoxometalates

Polyoxometalate (POM)-Layered Double Hydroxides (LDH) Composite Materials: Design and Catalytic Applications

Self-Assembly in Polyoxometalate and Metal Coordination-Based Systems: Synthetic Approaches and Developments

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