Polyoxometalates represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form structures that can bridge several length scales. The new building block principles that have been discovered are beginning to allow the design of complex clusters with desired properties and structures and several structural types and novel physical properties are examined. In this critical review the synthetic and design approaches to the many polyoxometalate cluster types are presented encompassing all the sub-types of polyoxometalates including, isopolyoxometalates, heteropolyoxometalates, and reduced molybdenum blue systems. As well as the fundamental structure and bonding aspects, the final section is devoted to discussing these clusters in the context of contemporary and emerging interdisciplinary interests from areas as diverse as anti-viral agents, biological ion transport models, and materials science.

Polyoxometalate clusters, nanostructures and materials: From self assembly to designer materials and devices

Polyoxometalates (POMs) are a subset of metal oxides that represent a diverse range of molecular clusters with an almost unmatched range of physical properties and the ability to form dynamic structures that can range in size from the nano- to the micrometer scale Herein we present the very latest developments from synthesis to structure and function of POMs We discuss the possibilities of creating highly sophisticated functional hierarchical systems with multiple, interdependent, functionalities along with a critical analysis that allows the non-specialist to learn the salient features We propose and present a "periodic table of polyoxometalate building blocks" We also highlight some of the current issues and challenges that need to be addressed to work towards the design of functional systems based upon POM building blocks and look ahead to possible emerging application areas

Polyoxometalates: Building Blocks for Functional Nanoscale Systems

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

Photo- and Electrochromism of Polyoxometalates and Related Materials

Polyoxometalates: Very large clusters - Nanoscale magnets

[Mo154(NO)14O420(OH)28(H2O)70](25 ± 5)−: A Water‐Soluble Big Wheel with More than 700 Atoms and a Relative Molecular Mass of About 24000

The compounds Cs12[VIV18O42(H2O)]·14H2O (1a), K12[VIV18O42(H2O)]·16H2O (1b), Rb12[VIV18O42(H2O)]·19H2O (1c), K9[H3VIV18O42(H2O)]·14H2O·4N2H4 (1d), K11[H2VIV18O42(Cl)]·13H2O·2N2H4 (2a), K9[H4VIV18O4...

Polyoxovanadates: High-Nuclearity Spin Clusters with Interesting Host−Guest Systems and Different Electron Populations. Synthesis, Spin Organization, Magnetochemistry, and Spectroscopic Studies

The compounds (NMe4)5[As2Mo8V4AsO40] . 3 H2O 2a, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] . 65 H2O 3a, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] . 14 H2O 3b and (NH4)12[Mo36(NO)4O108(H2O)16] . 33 H2O 4a (3a and 4a were not correctly reported in the literature regarding to their composition, structures and the oxidation states of the metal centres) which contain large isolated anionic species, have been prepared (among them 3 a, 3 b, and 4 a in rather high yield) and characterized by complete crystal structure analysis as well as IR/Raman, UV/VIS/NIR, ESR spectroscopy and magnetic susceptibility measurements, redox titrations, bond valence sum calculations, elemental analyses and thermogravimetric studies. Perspectives for polyoxometalate chemistry referring to the synthesis of ''extremely'' large nanoscaled species are discussed, together with the occurrence of a large transferable {Mo17} building block in the compounds 3a, 3b and 4a which also exists in the corresponding iron compound Na3(NH4)12[H15Mo57Fe6(NO)6O183(H2O)18] . 76H2O 7a.

New Perspectives in Polyoxometalate Chemistry by isolation of compounds containing very large moieties as transferable building blocks: (NMe4)5[As2Mo8V4AsO40] · 3H2O, (NH4)21[H3Mo57V6(NO)6O183(H2O)18] · 65 H2O, (NH2Me2)18(NH4)6[Mo57V6(NO)6O183(H2O)18] · 14 H2O, and (NH4)12[Mo36(NO)4O108(H2O)16] · 33 H2O

Jochen Meyer

Papers

[Mo154(NO)14O420(OH)28(H2O)70](25 ± 5)−: A Water‐Soluble Big Wheel with More than 700 Atoms and a Relative Molecular Mass of About 24000

Polyoxovanadates: High-Nuclearity Spin Clusters with Interesting Host−Guest Systems and Different Electron Populations. Synthesis, Spin Organization, Magnetochemistry, and Spectroscopic Studies

Molybdenum blue: A 200 year old mystery unveiled

[Mo154(NO)14O420(OH)28(H2O)70](25 ± 5)−: ein wasserlösliches Riesenrad mit mehr als 700 Atomen und einer relativen Molekülmasse von ca. 24000