Topic
Polyoxometalate
About: Polyoxometalate is a research topic. Over the lifetime, 3493 publications have been published within this topic receiving 94123 citations. The topic is also known as: POM.
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TL;DR: It is reported for the first time polyoxometalate (POM)-based single-molecule magnets with mononuclear transition metal cores with Mononuclear paramagnetic metal ions under the applied dc field.
83 citations
TL;DR: The Keggin-anions being immobilized as part of the metal N-heterocyclic multi-carboxylic acid frameworks not only enhance the thermal stability of compounds 2 and 3, but also introduce functionality inside their structures, thereby, realizing four approaches in the 1D hydrophilic channel used to engender proton conductivity in MOFs for the first time.
Abstract: We have succeeded in constructing a metal-organic framework (MOF), [Cu(bpdc)(H(2)O)(2)](n) (H(2) bpdc=2,2'-bipyridyl-3,3'-dicarboxylic acid, 1), and two poly-POM-MOFs (POM=polyoxometalate), {H[Cu(Hbpdc)(H(2)O)(2)](2) [PM(12)O(40)]·nH(2)O}(n) (M=Mo for 2, W for 3), by the controllable self-assembly of H(2) bpdc, Keggin-anions, and Cu(2+) ions based on electrostatic and coordination interactions. Notably, these three compounds all crystallized in the monoclinic space group P2(1)/n, and the Hbpdc(-) and bpdc(2-) ions have the same coordination mode. Interestingly, in compounds 2 and 3, Hbpdc(-) and the Keggin-anion are covalently linked to the transition metal copper at the same time as polydentate organic ligand and as polydentate inorganic ligand, respectively. Complexes 2 and 3 represent new and rare examples of introducing the metal N-heterocyclic multi-carboxylic acid frameworks into POMs, thereby, opening a pathway for the design and the synthesis of multifunctional hybrid materials based on two building units. The Keggin-anions being immobilized as part of the metal N-heterocyclic multi-carboxylic acid frameworks not only enhance the thermal stability of compounds 2 and 3, but also introduce functionality inside their structures, thereby, realizing four approaches in the 1D hydrophilic channel used to engender proton conductivity in MOFs for the first time. Complexes 2 and 3 exhibit good proton conductivity (10(-4) to ca. 10(-3) S cm(-1)) at 100 °C in the relative humidity range 35 to about 98%.
83 citations
TL;DR: Two kinds of assembly structures (nanorolls and hollow spindles) based on the palladium substituted Wells–Dawson polyoxometalate (Pd-POM) showed high catalytic activity for both the Suzuki–Miyaura coupling reaction and semihydrogenation reaction.
Abstract: The challenge with single-atom catalysts (SACs) is in designing a highly definite structure with accurate location of the single atom and high catalytic efficiency. The noble metal substituted polyoxometalates seem to be a kind of SAC because of their well resolved crystal structure. Here, we got two kinds of assembly structures (nanorolls and hollow spindles) based on the palladium substituted Wells–Dawson polyoxometalate (Pd-POM), which consists of isolated Pd atoms. Both the nanorolls and hollow spindles showed high catalytic activity for both the Suzuki–Miyaura coupling reaction and semihydrogenation reaction. The difference of the chemical surroundings between the nanorolls and hollow spindles leads to their discrepancy in the catalytic activity of semihydrogenation.
83 citations
TL;DR: In this paper, the surface of POM clusters was modified by organic surfactant through single-phase approach, by carefully controlling and varying clusters surrounding environment, all assemblies were found to reverse into each other.
Abstract: Reversible self-assembly of Keggin structure polyoxometalate (POM) nanoclusters into nanodisks, nanocones, and nanotubes is described. The surface of POM clusters was modified by organic surfactant through single-phase approach. By carefully controlling and varying clusters surrounding environment, all assemblies were found to reverse into each other. The different assemblies and their evolutions from each other were studied by scanning electron microscopy and optical microscopy while the inner structure was investigated by transmission electron microscopy. The formation and transformation of different assembly shapes into each other is interpreted by considering electrostatic binding of surfactant molecules with the POM cluster, number of surfactant molecules attached, and particular surrounding environment arising from the optimized mixed solvent.
83 citations
TL;DR: The corrosion resistance against acetic acid vapors and simulated "acid rain" was significantly improved compared with commercial ionic liquids or solid polyoxometalate coatings.
Abstract: Corrosion is a global problem for any metallic structure or material. Herein we show how metals can easily be protected against acid corrosion using hydrophobic polyoxometalate-based ionic liquids (POM-ILs). Copper metal disks were coated with room-temperature POM-ILs composed of transition-metal functionalized Keggin anions [SiW11O39TM(H2O)]n− (TM=CuII, FeIII) and quaternary alkylammonium cations (CnH2 n+1)4N+ (n=7–8). The corrosion resistance against acetic acid vapors and simulated “acid rain” was significantly improved compared with commercial ionic liquids or solid polyoxometalate coatings. Mechanical damage to the POM-IL coating is self-repaired in less than one minute with full retention of the acid protection properties. The coating can easily be removed and recovered by rinsing with organic solvents.
82 citations