ChemInform Abstract: The Trinity of Polyoxometalates: Connecting {M 12 } Keggin and {M 18 } Dawson Clusters to Triangles (original) (raw)
Related papers
Modular Inorganic Polyoxometalate Frameworks Showing Emergent Properties: Redox Alloys
Angewandte Chemie, 2010
The targeted synthesis of new extended modular frameworks exhibiting specific properties is a principal challenge of modern chemistry research. [1] Many inorganic frameworks and metal-organic frameworks (MOFs) have been reported, but the fine manipulation of their electronic properties remains challenging. One such approach could be the development of molecular alloys, analogous to metal alloys, yet this idea has rarely been applied, and three dimensional (3D) framework alloys based upon molecular building blocks have not yet been fully realized. Conceptually, the design of 3D framework alloys could be achieved if the components of two isostructural frameworks "A" and "B" could be mixed at the molecular level (in any proportion) forming a crystal of AB units, perfectly arranged, so the AB alloy is also isostructural to frameworks A and B. [9] The potential applications of such an approach are highly appealing, since the combination of coordination-compound-based building blocks, exhibiting different electronic properties, could allow the targeted tuning of frameworks with properties intermediate between A and B; and even the realization of "emergent" or unexpected properties for the alloy.
Crystal Growth & Design, 2012
The mechanism for the syntheses of inorganic framework materials based solely on polyoxometalate Keggin clusters has been examined and their electronic properties have been investigated. The assembly of the m odular net work co mpounds wit h th e mo lecular formula (C 4 H 10 NO) n [W 72 M 12 O 268 X 7 ] (with the heteroatom X = Si or Ge and the heterometal M = Co(II) or Mn(III)) is based on the isomerization of the metastable precursor material [γ-XW 10 O 36 ] 8− , followed by the inclusion of the heterometal and subsequent assembly into the extended framework structure. The two frameworks featuring manganese substitution can be dis-and reassembled in a recrystallization process while the cobalt versions do not show comparable behavior. The intrinsic differences of the four compounds with regards to their heteroatom and heterometal substitution are shown in terms of their redox behavior.
Inorganic Chemistry, 2001
New organic derivatives of "inverse-Keggin" polyoxometalate (POM) clusters, [Mo 12 O 46 (AsR) 4 ] 4-(R) C 6 H 4-4-COOH, C 6 H 3-4-OH-3-NO 2 , C 6 H 4-4-OH), have been synthesized. Structures of the corresponding sodium or iron salts were elucidated by single-crystal X-ray diffraction and shown to be 3D structures connected through hydrogen bonds and/or O-Na-O linkages. Parameters which influence the final solid-state architecture, such as the crystallizing solvent, organic moiety, and counterions, have been examined. The hydrogen-bonding ability of the solvent affects the connectivity of the POM clusters through interactions with the organic group and the inorganic core. The organic groups influence the structure through hydrogen bonds to other organic groups, to neighboring clusters, and/or to solvent molecules. Hydrogen bonding between the organic groups and the solvent appears to inhibit some possible connectivity patterns, such as the hydrogen-bonded dimerization of carboxylic acid groups. Na + ions were found directly bonded to the cluster oxo ligands and provided linkages between clusters. Larger cations, such as transition metals, did not show this interaction, and other bonding methods dominated.
Engineering polyoxometalates with emergent properties
Chemical Society Reviews, 2012
Polyoxometalates are clusters of metal-oxide units, comprising a large diversity of nanoscale structures, and have many common building blocks; in fact polyoxometalate clusters are perhaps the largest non-biologically derived molecules structurally characterised. Not only can polyoxometalates have gigantic nanoscale molecular structures, but they also a have a vast array of physical properties, many of which can be specifically 'engineered-in'. Here we describe how building block libraries of polyoxometalates can be used to construct systems with important catalytic, electronic, and structural properties. We also show that it is possible to construct complex chemical systems based upon polyoxometalates, manipulating the templating/self templating rules to exhibit emergent processes from the molecular to the macroscopic scale.
Tuning the Dimensionality of Polyoxometalate-Based Materials by Using a Mixture of Ligands
Crystal Growth & Design, 2015
Five molecular one-, two-, or three-dimensional (1D, 2D, or 3D) organic−inorganic hybrid polyoxometalates (POMs) based on the {ε-PMo V 8 Mo VI 4 O 40 Zn 4 } (εZn) Keggin unit have been synthesized under hydrothermal conditions using a mixture of O-and N-donor ligands. (TBA) 6 [PMo V 8 -Mo VI 4 O 37 (OH) 3 Zn 4 ] 2 (C 14 H 8 O 4 ) 3 ·6H 2 O (ε 2 (biphen) 3 ) is a 3D material with two interpenetrated networks built from dimeric (εZn) 2 POMs linked by 4,4′-biphenyldicarboxylate (biphen) ligands. (TBA) 2 [PMo V 8 Mo VI 4 O 38 (OH) 2 Zn 4 ]-(C 7 H 6 N 2 ) 3 (C 14 H 8 O 4 ) 1/2 ·H 2 O (ε(bim) 3 (biphen) 1/2 ), (TBA) 3 -[ P M o V 8