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

Photo- and Electrochromism of Polyoxometalates and Related Materials

Dendrimers in Supramolecular Chemistry: From Molecular Recognition to Self-Assembly.

Polyoxometalates: Very large clusters - Nanoscale magnets

A key reaction in the biological and material world is the controlled linking of simple (molecular) building blocks, a reaction with which one can create mesoscopic structures, which, for example, contain cavities and display specifically desired properties, but also compounds that exhibit typical solid-state structures. The best example in this context is the chemistry of host–guest interactions, which spans the entire range from three- and two-dimensional to one- and “zero-dimensional”, discrete host structures. Members of the class of multidimensional compounds have been classified as such for a long time, for example, clathrates and intercalation compounds. Thus far, however, there are no classifications for discrete inorganic host–guest compounds. The first systematic approach can be applied to novel polyoxometalates, a class of compounds which has only recently become known. Molecular recognition; tailor-made, molecular engineering; control of fragment linkage of spin organization and crystallization; cryptands and coronands as “cages” for cations, anions or anion–cation aggregates as sections of ionic lattices; anions within anions, receptors; host–guest interactions; complementarity, as well as the dialectic terms reduction and emergence are important terms and concepts of supramolecular inorganic chemistry. Of particular importance for future research is the comprehension of the mesoscopic area (molecular assemblies)—that between individual molecules and solids (“substances”)—which acts in the biological world as carrier of function and information and for which interesting material properties are expected. This area is accessible through certain variations of “controlled” self-organization processes, which can be demonstrated by using examples from the chemistry of polyoxometalates. The comprehension of the laws that rule the linking of simple polyhedra to give complex systems enables one to deal with numerous interdisciplinary areas of research: crystal physics and chemistry, heterogeneous catalysis, bioinorganic chemistry (biomineralization), and materials science. In addition, conservative self-organization processes, for example template-directed syntheses, are of importance for natural philosophy in the context of the question about the inherent properties of material systems.

Supramolecular inorganic chemistry : small guests in small and large hosts

[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 (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

Eine Schlusselreaktion der belebten und unbelebten Welt ist die gesteuerte Verknupfung von einfachen (molekularen) Bausteinen, eine Reaktion, mit der man grundsatzlich mesoskopische Gebilde, z.B. solche mit Hohlraumen und beliebigen gewunschten Eigenschaften, erzeugen kann, aber auch Verbindungen mit typischen Festkorperstrukturen. Beispielhaft nutzt diese Reaktion die Wirt-Gast-Chemie, die den Bogen von drei- und zweidimensionalen zu ein- und nulldimensionalen diskreten Wirtstrukturen spannt. Wahrend man zu den mehrdimensionalen Strukturen die schon seit langem bekannten Clathrate und Intercalationsverbindungen zahlt, sind diskrete anorganische Wirt-Gast-Verbindungen, zu denen auch die Polyoxometallate gehoren, bisher nicht klassifiziert worden. Molekulare Erkennung; molekulares „Engineering”; Steuerung der Verknupfung von Fragmenten, der Spinorganisation sowie der Kristallisation; Cryptanden und Coronanden als „Kafige” fur Kationen, Anionen- und sogar Anionen-Kationen-Aggregate (als Ausschnitte aus Ionengittern); Anionen in Anionen; Rezeptoren; Wirt-Gast-Wechselwirkungen, Komplementaritat sowie das dialektische Begriffspaar Reduktion und Emergenz sind wichtige Begriffe der Supramolekularen Anorganischen Chemie. Von besonderer Bedeutung ist das Verstandnis des mesoskopischen Bereiches - desjenigen zwischen einzelnen Molekulen einerseits sowie makroskopischen Molekulverbanden und Festkorpern („Substanzen”) andererseits -, der in der biologischen Welt als Funktions- und Informationstrager dient und fur den interessante Materialeigenschaften zu erwarten sind. Dieser Bereich ist durch „gesteuerte” Selbstorganisationsprozesse zuganglich, wie an Schulbeispielen aus der Polyoxometallatchemie gezeigt werden kann. Das Verstandnis der Gesetzmasigkeiten, die der Verknupfung von einfachen Polyedereinheiten zu komplexen Systemen zugrunde liegen, ermoglicht die Beschaftigung mit zahlreichen interdisziplinaren Forschungsgebieten in der Kristallphysik und -chemie, der heterogenen Katalyse, der Bioanorganischen Chemie (Biomineralisation) und den Materialwissenschaften. Konservative Selbstorganisationsprozesse, z.B. templatgesteuerte Synthesen, sind zudem fur die Naturphilosophie im Zusammenhang mit der Frage nach inharenten Eigenschaften materieller Systeme von Bedeutung.

Supramolekulare Anorganische Chemie: von Gästen in kleinen und großen Wirten

Cation Inclusion within the Mixed‐Valence Polyanion Cluster [(MoVIO3)4Mo 12VO28(OH)12]8−: Syntheses and Structures of (NH4)7[NaMo16(OH)12O40]·4H2O and (Me2NH2)6[H2Mo16(OH)12O40]

S. Dillinger

Papers

Supramolecular inorganic chemistry : small guests in small and large hosts

[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

Supramolekulare Anorganische Chemie: von Gästen in kleinen und großen Wirten

Cation Inclusion within the Mixed‐Valence Polyanion Cluster [(MoVIO3)4Mo 12VO28(OH)12]8−: Syntheses and Structures of (NH4)7[NaMo16(OH)12O40]·4H2O and (Me2NH2)6[H2Mo16(OH)12O40]