Polyoxometalates (POMs) are discrete anionic metaloxygen clusters which can be regarded as soluble oxide fragments. They exhibit a great diversity of sizes, nuclearities, and shapes. They are built from the connection of {MOx} polyhedra, M being a d-block element in high oxidation state, usually VIV,V, MoVI, or WVI.1 While these species have been known for almost two centuries, they still attract much interest partly based on their large domains of applications. They play a great role in various areas ranging from catalysis,2 medicine,3 electrochemistry,4 photochromism,5 to magnetism.6 This palette of applications is intrinsically due to the combination of their added value properties (redox properties, large sizes, high negative charges, nucleophilicity...). Parallel to this domain, the organic-inorganic hybrids area has followed a similar expansion during the last 10 years. The concept of organic-inorganic hybrid materials * To whom correspondence should be addressed. E-mail: dolbecq@ chimie.uvsq.fr. Chem. Rev. 2010, 110, 6009–6048 6009

Hybrid Organic−Inorganic Polyoxometalate Compounds: From Structural Diversity to Applications

This review (over 380 references) summarizes metal–organic frameworks (MOFs), Materials Institute Lavoisier (MILs), iso-reticular metal–organic frameworks (IR-MOFs), porous coordination networks (PCNs), zeolitic metal–organic frameworks (ZMOFs) and porous coordination polymers (PCPs) with selected examples of their structures, concepts for linkers, syntheses, post-synthesis modifications, metal nanoparticle formations in MOFs, porosity and zeolitic behavior for applications in gas storage for hydrogen, carbon dioxide, methane and applications in conductivity, luminescence and catalysis.

MOFs, MILs and more: concepts, properties and applications for porous coordination networks (PCNs)

Triazoles and tetrazoles: Prime ligands to generate remarkable coordination materials

The articles published in the tenth anniversary issue of CrystEngComm are reviewed. The issue highlighted the state-of-the-art of crystal engineering and new trends and developing areas in crystal engineering. In particular, the following article emphasises developments in the areas of intermolecular interactions, notably hydrogen and halogen bonds; metal–organic frameworks or coordination polymers; polymorphism and solvates.

Recent advances in crystal engineering

Ever since the discovery and development of polyoxometalates (POMs), it has been known that they can exist in electron-rich reduced forms of different archetypes, structural flexibilities and functionalities. There are now reliable synthetic strategies for electron-rich POMs — materials that have unique and potentially useful catalytic, electronic and magnetic properties. This Review covers the synthesis and applications of these reduced species, and also highlights their differences and advantages relative to fully oxidized POMs. More than 200 reduced POM structures are described in this Review, with emphasis placed on how reduction influences POM structure, function and properties. The metals in polyoxometalates need not be in their highest oxidation states. Indeed, polyoxometalates can exist in reduced forms, and several different metals can be incorporated into various structural archetypes. This Review describes the synthesis and characterization of these complexes, along with their topical catalytic, electronic and biological properties.

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Synthesis, structures and applications of electron-rich polyoxometalates

Through tuning the length of flexible bis(triazole) ligands and different metal ion coordination geometries, four Wells-Dawson polyoxoanion-based hybrid compounds, [Cu6(btp)3(P2W18O62)]·3H2O (1) (btp = 1,3-bis(1,2,4-triazol-1-y1)propane), [Cu6(btb)3((P2W18O62)]·2H2O (2), [Cu3(btb)6(P2W18O62)]·6H2O (btb = 1,4-bis(1,2,4-triazol-1-y1)butane) (3), and [Cu3(btx)5.5((P2W18O62)]·4H2O (btx = 1,6-bis(1,2,4-triazol-1-y1)hexane) (4), were synthesized and structurally characterized. In compound 1, the metal-organic motif exhibits a ladder-like chain, which is further fused by the ennead-dentate [P2W18O62]6− anions to construct a 3D structure. In compound 2, the metal-organic motif exhibits an interesting Cu−btb grid layer, and the ennead-dentate polyoxoanions are sandwiched by two Cu−btb layers to construct a 3D structure. Compound 3 exhibits a (42·62·82) 3D Cu−btb framework with square and hexagonal channels arranged alternately. The hexa-dentate polyoxoanions incorporate only into the hexagonal channels. In compoun...

Assembly of the Highest Connectivity Wells-Dawson Polyoxometalate Coordination Polymer: the Use of Organic Ligand Flexibility

Three novel polyoxometalate derivatives decorated by transition metal complexes have been hydrothermally synthesized. Compound 1 consists of [PMoVI6MoV2VIV8O44{Co (2,2‘-bipy)2(H2O)}4]3+ polyoxocations and [PMoVI4MoV4VIV8O44{Co(2,2‘-bipy)2(H2O)}2]3- polyoxoanions, which are both built on mixed-metal tetracapped [PMo8V8O44] subunits covalently bonded to four or two {Co(2,2‘-bpy)2(H2O)}2+ clusters via terminal oxo groups of the capping V atoms. Compound 2 is built on [PMoVI8VIV6O42{CuI(phen)}2]5- clusters constructed from mixed-metal bicapped [PMoVI8VIV6O42]7- subunits covalently bonded to two {Cu(phen)}+ fragments in the similar way to 1. The structure of 3 is composed of [PMoVI9MoV3O40]6- units capped by two divalent Ni atoms via four bridging oxo groups. The crystal data for these are the following:  C120H126Co6Mo16N24O103P2V16 (1), triclinic P1, a = 15.6727(2) A, b = 17.3155(3) A, c = 19.5445(2) A, α = 86.1520(1)°, β = 81.2010(1)°, γ = 63.5970(1)°, Z = 1; C120H85Cu6Mo8N20O44PV6 (2), triclinic P1, a = 1...

Modified Polyoxometalates: Hydrothermal Syntheses and Crystal Structures of Three Novel Reduced and Capped Keggin Derivatives Decorated by Transition Metal Complexes

By introducing the flexible 1,1‘-(1,4-butanediyl)bis(imidazole) (bbi) ligand into the polyoxovanadate system, five novel polyoxoanion-templated architectures based on [As8V14O42]4- and [V16O38Cl]6- building blocks were obtained:  [M(bbi)2]2[As8V14O42(H2O)] [M = Co (1), Ni (2), and Zn (3)], [Cu(bbi)]4[As8V14O42(H2O)] (4), and [Cu(bbi)]6[V16O38Cl] (5). Compounds 1−3 are isostructural, and they exhibit a binodal (4,6)-connected 2D structure with Schlafli symbol (34·42)(34·44·54·63)2, in which the polyoxoanion induces a closed four-membered circuit of M4(bbi)4. Compound 4 exhibits an interesting 3D framework constructed from tetradentate [As8V14O42]4- cluster anions and cationic ladderlike double chains. There exists a bigger M8(bbi)6O2 circuit in 4. The 3D extended structure of 5 is composed of heptadentate [V16O38Cl]6- anions and flexural cationic chains; the latter consists of six Cu(bbi) segments arranged alternately. It presents the largest 24-membered circuit of M24(bbi)24 so far observed made of bbi mo...

High-Dimensional Assembly Depending on Polyoxoanion Templates, Metal Ion Coordination Geometries, and a Flexible Bis(imidazole) Ligand

Three novel supramolecular assemblies constructed from polyoxometalate and crown ether building blocks, [(DB18C6)Na(H2O)1.5]2Mo6O19·CH3CN, 1, and [{Na(DB18C6)(H2O)2}3(H2O)2]XMo12O40·6DMF·CH3CN (X = P, 2, and As, 3; DB18C6 = dibenzo-18-crown-6; DMF = N,N-dimethylfomamide), have been synthesized and characterized by elemental analyses, IR, UV−vis, EPR, TG, and single crystal X-ray diffraction. Compound 1 crystallizes in the tetragonal space group P4/mbm with a = 16.9701(6) A, c = 14.2676(4) A, and Z = 2. Compound 2 crystallizes in the hexagonal space group P63/m with a = 15.7435(17) A, c = 30.042(7) A, γ = 120°, and Z = 2. Compound 3 crystallizes in the hexagonal space group P63/m with a = 15.6882(5) A, c = 29.9778(18) A, γ = 120°, and Z = 2. Compound 1 exhibits an unusual three-dimensional network with one-dimensional sandglasslike channels based on the extensive weak forces between the oxygen atoms on the [Mo6O19]2- polyoxoanions and the CH2 groups of crown ether molecules. Compounds 2 and 3 are isostruct...

Hengqing Jia

Papers

Assembly of the Highest Connectivity Wells-Dawson Polyoxometalate Coordination Polymer: the Use of Organic Ligand Flexibility

Modified Polyoxometalates: Hydrothermal Syntheses and Crystal Structures of Three Novel Reduced and Capped Keggin Derivatives Decorated by Transition Metal Complexes

High-Dimensional Assembly Depending on Polyoxoanion Templates, Metal Ion Coordination Geometries, and a Flexible Bis(imidazole) Ligand

New high-dimensional networks based on polyoxometalate and crown ether building blocks.

Synthesis and crystal structure of a novel compound constructed from tris-(2,2′-bipy)ruthenium(II) and decatungstate