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.

Vibrational Spectroscopy of a Keggin Polyoxometalate on Metal Electrode Surfaces

Abstract: Polarization modulation infrared reflection−absorption spectroscopy and surface-enhanced Raman spectroscopy are used to interrogate the behavior of the Keggin-type polyoxometalate α-[SiW12O40]4- on...

Robust Cluster Building Unit: Icosanuclear Heteropolyoxocopperate Templated by Carbonate.

Abstract: The encapsulation of carbonate derived from atmospheric CO2 has resulted in an icosanuclear heteropolyoxocopperate, isolated as a metal-organic 1D chain, 2D sheet, or 3D framework, in which the Cu20 nanocluster represents the first eight-capped α-Keggin polyoxometalate with the late-transition-metal Cu(II) as the polyatom, CO3(2-) as the heteroanion, and OH(-) and suc(2-) or glu(2-) (H2suc=succinic acid; H2glu=glutaric acid) as the terminal ligands, which suggests a conceptual similarity to classical polyoxometalates. Even in the presence of competitive SO4(2-) in the assembly system, the CO3(2-) anion is still captured as a template to direct the formation of the Cu20 nanocluster, which indicates the stronger templation ability of CO3(2-) compared with SO4(2-). When other aliphatic dicarboxylates, such as glutaric acid, were used as ligands, the CO3(2-)-templated Cu20 nanocluster was maintained and acted as a cluster building unit (CBU) to be linked by two glutarate bridges to generate a distinct 1D metal-organic chain. This report presents not only a rare example of a huge anion-templated transition-metal cluster, but also its use as a robust CBU to construct novel coordination architectures. Variable-temperature magnetic susceptibility studies revealed that an antiferromagnetic interaction exists within the Cu20 nanocluster. The correlation between the coordination structure and the electron paramagnetic resonance spectra recorded of both powder and single-crystal samples are discussed in detail.

Novel copper-complex-substituted tungstogermanates.

Abstract: Two copper-complex-substituted tungstogermanates [Cu5(2,2‘-bpy)6(H2O)][GeW8O31]·9H2O, 1, and {[Cu5(2,2‘-bpy)5(H2O)][GeW9O34]}2·7H2O, 2 (2,2‘-bpy = 2,2‘-bipyridyl), have been hydrothermally synthesized and structurally characterized. X-ray structural analyses show that 1 is a rare tetralacunary Keggin anion of [B-β-GeW8O31]10- substituted by copper complexes, while dimer 2 consists of two trilacunary [B-α-GeW9O34]10- Keggin units bridged by copper complexes. Magnetic measurement for 2 shows the presence of antiferromagnetic interactions within the dinuclear Cu2+ cations.

Polyoxometalate-based manganese clusters as catalysts for efficient photocatalytic and electrochemical water oxidation

Abstract: A manganese containing polyoxometalate (POM) [Mn 3 (H 2 O) 3 (SbW 9 O 33 ) 2 ] 12− ( 1 ) was synthesized and characterized in detail. The photocatalytic activity of 1 is definitely better than other manganese containing POM water oxidation catalysts reported so far according to oxygen yield, whereas the analogues [Mn 3 (H 2 O) 5 (PW 9 O 34 ) 2 ] 9− ( 2 ) and [Mn 3 (H 2 O) 3 (AsW 9 O 33 ) 2 ] 12− ( 3 ) show no to slight photocatalytic O 2 evolution amount. Meanwhile, the electrocatalytic activities of 1 - 3 were investigated in 80 mM pH 9.0 borate buffer, which follows the catalytic activity order of 1 > 2 > 3 . Multiple experiments including UV−vis absorption, catalysts aging experiments, tetra- n -heptylammonium nitrate (THpANO 3 ) toluene extraction, electrochemical experiments and capillary electrophoretic measurements results confirm that catalyst 1 is a homogeneous molecular catalyst. No Mn 2+ (aq.) or manganese oxide under the reaction conditions of photocatalytic and electrochemical water oxidation was detected.

Tetrahedral connection of ε-Keggin-type polyoxometalates to form an all-inorganic octahedral molecular sieve with an intrinsic 3D pore system.

Abstract: A new type of polyoxometalate-based porous material was successfully synthesized. The new material is the first fully inorganic Keggin-type polyoxometalate-based microporous material with intrinsically ordered open micropores and is the third member of the small family of octahedral molecular sieves (OMSs). Twelve MoO6 or VO6 octahedra surround a central VO4 tetrahedron to form e-Keggin polyoxometalate building blocks (e-VMo9.4V2.6O40) that are linked by BiIII ions to form crystalline Mo–V–Bi oxide with a diamondoid topology. The presence of a tetrahedral shape of the e-Keggin polyoxometalate building block results in arrangement of microporosity in a tetrahedral fashion which is new in OMSs. Owing to its microporosity, this Mo–V–Bi oxide shows zeolitic-like properties such as ion-exchange and molecule adsorption.