Polyoxometalate-based open frameworks (POM-OFs) are extended architectures incorporating metal-oxide cluster units and comprise an emergent family of materials with a large diversity of topologies, structural flexibility and functionality at the nanoscale. Not only do POM-OFs present a wide range of configurable structures, but also a have a vast array of physical properties which reflect the properties of the various ‘modular’ molecular inputs. Here we describe the methodologies that can be used to construct POM-OF materials with important catalytic, electronic, and structural properties and discuss the advantages compared to the metal organic framework analogues. We also show that it is possible to construct POM-OF materials and design and/or fine tune their functionality by manipulating the initially generated building block libraries as well as by controlling the self-assembly towards the specific intermediate (POM) species which is the chemical and structural “information” carrier of the targeted POM-OF material.

Polyoxometalate based open-frameworks (POM-OFs)

A series of novel manganese(II)-substituted polyoxometalates, [(MnII(H2O)3)2(WO2)2(BiW9O33)2]10- (1), [(MnII(H2O))3(SbW9O33)2]12- (2), and [(MnII(H2O)3)2(MnII(H2O)2)2(TeW9O33)2]8- (3), were synthesized and characterized by X-ray structure analyses. The use of these oxidatively and solvolytically stable heteropolyanions as homogeneous catalysts for the epoxidation of dienes was investigated by gas chromatography/mass spectrometry, IR spectroscopy, UV−visible studies, and cyclic voltammetric measurements. The catalytic performance is exemplified by the model substrate (R)-(+)-limonene, at ambient temperatures in a biphasic system, with excellent regioselectivities, >99%, and very high turnovers even with only a small molar excess of hydrogen peroxide.

Highly Efficient Catalysts in Directed Oxygen-Transfer Processes: Synthesis, Structures of Novel Manganese-Containing Heteropolyanions, and Applications in Regioselective Epoxidation of Dienes with Hydrogen Peroxide

The reactivity of the [α-SiW 1 1 O 3 9 ] 8 - monovacant polyoxometalate with lanthanide has been investigated for four different trivalent rare-earth cations (Ln = Nd I I I , Eu I I I , Gd I I I , Yb I I I ). The crystal structures of KCs 4 [Yb(α-SiW 1 1 O 3 9 )-(H 2 O) 2 ].24H 2 O (1), K 0 . 5 Nd 0 . 5 [Nd 2 (α-SiW 1 1 O 3 9 )(H 2 O) 1 1 ].17H 2 O (2a), and Na 0 . 5 Cs 4 . 5 [Eu(α-SiW 1 1 O 3 9 )(H 2 O) 2 ].23H 2 O (3a) are reported. The solid-state structure of compound 1 consists of linear wires built up of [α-SiW 1 1 O 3 9 ] 8 - anions connected by Yb 3 + cations, while the linkage of the building blocks by Eu 3 + centers in 3a leads to the formation of zigzag chains. In 2a, dimeric [Nd 2 (α-SiW 1 1 O 3 9 ) 2 (H 2 O) 8 ] 1 0 - entities are linked by four Nd 3 + cations. The resulting chains are connected by lanthanide ions, leading to a bidimensional arrangement. Thus, the dimensionality, the organization of the polyoxometalate building units, and the Ln/[α-SiW 1 1 O 3 9 ] 8 - ratio in the solid state can be tuned by choosing the appropriate lanthanide. The luminescent properties of compound 3a have been studied, showing that, in solution, the polymer decomposes to give the monomeric complex [Eu(α-SiW 1 1 O 3 9 )(H H O) 4 ] 5 - . The lability of the four exogenous ligands connected to the rare earth must allow the functionalization of this lanthanide polyanion.

Solid-State and solution studies of [Ln(n)(SiW11O39)] polyoxoanions: an example of building block condensation dependent on the nature of the rare earth.

Eine Blaupause fur das Design von Oxidmaterialien kann uns die Natur liefern, da sie bei Biomineralisationsprozessen und bei der Hydrothermalsynthese komplexer Mineralien anorganische Mikrostrukturen beeinflussen kann. Eine Anleihe bei dieser Fahigkeit fuhrt zu einer ganz neuen Klasse von Materialien, bei denen organische Komponenten eine Rolle bei der Kontrolle uber die anorganischen Mikrostrukturen spielen. Der Einsatz von Verbindungen aus der bestandig wachsenden Klasse polymerer Komplexkationen ermoglicht die Herstellung von Molybdanoxiden mit neuartigen Substrukturen (siehe das im Bild gezeigte Beispiel).

Organisch‐anorganische Hybridmaterialien: von „einfachen”︁ Koordinationspolymeren zu Molybdänoxiden mit Organodiamin‐Templaten

A two-dimensional network constructed from hexamolybdate, octamolybdate and [Cu3(4,7-phen)3]3+ clusters: [{Cu3(4,7-phen)3}2{Mo14O45}]

Synthesis, structure of polymeric cobalt-containing heteropolytungstates and their applications in oxidation catalysis

Bleach composition comprising one or more bleaching agents and one or more polyoxometallates of the formula: (Q)q(A a X x M m O y Z z(H2O)b).cndot.cH2O as bleaching catalyst, the symbols Q, A, X, M, Z, q, a, x, m, y, z, b and c being as defined in the description. These polyoxometallates increase the bleaching activity, especially at lower washing temperatures.

Bleaching composition comprising polyoxometallates as bleaching catalyst

A bleach compsn contains: (a) a bleaching agent; and (b) a polyoxymetallate as bleach catalyst

Bleaching composition comprising polyoxometalates bleach catalyst

Manganiferous catalytically active polyoxometalates of formula (1) (Q)q (MnpAaXxYyMmOdZz(H2O)b) c H2O and the process for the manufacture thereof. In formula (I), Q, A, X, Y, M, Z, q, p, a, x, y, m, z, d, b and c have the following meaning: Q represents one or more cations selected from the group H, Li, K, Na, Rb, Cs, Ca, Mg, Sr, Ba, Al, PR?1R2R3R4 and NR1R2R3R4 with R1, R2, R3 et R4? representing H or C?1?-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript q falls in a range of 1 to 60, more especially in a range of 1 to 40 and, in the case of a single-value counter-cation, also describes the charge on the anionic unit; Mn is manganese; subscript p falls in a range of 0.1 to 10, A is a heterometal and represents one or more transitional metals of the 2?nd to 8th? subsidiary groups except for Zn, especially Ru, V, Ti, Zr, Cr, Fe, Co, Cu, Sn, Ni, Re or Os; subscript a falls in a range of 0 to 10; X represents one or more elements selected from the group Ga, B, P, Si, Ge, As, F, Cl, Br and J; subscript x falls in the range of 0 to 10; Y represents Sb, S, Se, Te or Bi; subscript y falls in the range of 0.1 to 10; M represents one or more transition metals selected from the group Mo, W, Nb, Ta and V; subscript m falls in the range of 0.5 to 60; Z represents one or more anions selected from the group OH?-, F-, Cl-, Br-, I-, N?3-, NO3-, ClO4-, NCS-, SCN-, PF?6?-, RSO3-, RSO4-, CF3SO3-, BR4-, BF4-, OAc- with R = H, C?1?-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript z falls in the range 0 to 10; subscript d represents the number of oxygen atoms necessary to balance the charge and b and c are numbers in the range 0 to 50. The oxidisation catalysts described are particularly good for activating peroxide compounds and oxygen.

Manganiferous polyoxometalates, synthesis and use thereof

Manganiferous catalytically active polyoxometalates of formula (1) (Q)q (MnpAaXxYyMmOdZz(H2O)b) c H2O and the process for the manufacture thereof. In formula (I), Q, A, X, Y, M, Z, q, p, a, x, y, m, z, d, b and c have the following meaning: Q represents one or more cations selected from the group H, Li, K, Na, Rb, Cs, Ca, Mg, Sr, Ba, Al, PRRRR and NRRRR with R, R, R et R representing H or C1-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript q falls in a range of 1 to 60, more especially in a range of 1 to 40 and, in the case of a single-value counter-cation, also describes the charge on the anionic unit; Mn is manganese; subscript p falls in a range of 0.1 to 10, A is a heterometal and represents one or more transitional metals of the 2 to 8 subsidiary groups except for Zn, especially Ru, V, Ti, Zr, Cr, Fe, Co, Cu, Sn, Ni, Re or Os; subscript a falls in a range of 0 to 10; X represents one or more elements selected from the group Ga, B, P, Si, Ge, As, F, Cl, Br and J; subscript x falls in the range of 0 to 10; Y represents Sb, S, Se, Te or Bi; subscript y falls in the range of 0.1 to 10; M represents one or more transition metals selected from the group Mo, W, Nb, Ta and V; subscript m falls in the range of 0.5 to 60; Z represents one or more anions selected from the group OH, F, Cl, Br, I, N3, NO3, ClO4, NCS-, SCN-, PF6, RSO3, RSO4, CF3SO3, BR4, BF4, OAc with R = H, C1-C20-alkyl, C5-C8-cycloalkyl or aryl; subscript z falls in the range 0 to 10; subscript d represents the number of oxygen atoms necessary to balance the charge and b and c are numbers in the range 0 to 50. The oxidisation catalysts described are particularly good for activating peroxide compounds and oxygen.

Bernd Dr Scharbert

Papers

Synthesis, structure of polymeric cobalt-containing heteropolytungstates and their applications in oxidation catalysis

Bleaching composition comprising polyoxometallates as bleaching catalyst

Bleaching composition comprising polyoxometalates bleach catalyst

Manganiferous polyoxometalates, synthesis and use thereof

Mangan enthaltende Polyoxometallate, Synthese und Verwendung