The design of highly flexible framework materials requires organic linkers, whereas inorganic materials are more robust but inflexible. Here, by using linkable inorganic rings made up of tungsten oxide (P 8 W 48 O 184 ) building blocks, we synthesized an inorganic single crystal material that can undergo at least eight different crystal-to-crystal transformations, with gigantic crystal volume contraction and expansion changes ranging from −2,170 to +1,720 Å 3 with no reduction in crystallinity. Not only does this material undergo the largest single crystal-to-single crystal volume transformation thus far reported (to the best of our knowledge), the system also shows conformational flexibility while maintaining robustness over several cycles in the reversible uptake and release of guest molecules switching the crystal between different metamorphic states. This material combines the robustness of inorganic materials with the flexibility of organic frameworks, thereby challenging the notion that flexible materials with robustness are mutually exclusive.

We describe why the cyclic heteropolyanion [P8W48O184]40- (abbreviated as {P8W48}) is an ideal building block for the construction of intrinsically porous framework materials by classifying and analyzing >30 coordination polymers incorporating this polyoxometalate (POM) ligand. This analysis shows that the exocyclic coordination of first-row transition metals (TMs) to {P8W48} typically yields frameworks which extend through {W-O-TM-O-W} bridges in one, two, or three dimensions. However, despite the rich structural diversity of such compounds, the coordination of TMs to the {P8W48} ring is poorly understood, and therefore largely unpredictable, and had not until now been present with any structural classification that could allow rational design. Herein, not only do we present a new approach to understand and classify this new class of materials, we also present three {P8W48}-based frameworks which complement those frameworks which have previously been described. These new compounds help us postulate a new taxonomy of these materials. This is possible because the TM coordination sites of the {P8W48} ring are found, once fully mapped, to lead to well-defined classes of connectivity. Together, analysis provides insight into the nature of the building block connectivity within each framework, to facilitate comparisons between related structures, and to fundamentally unite this family of compounds. Hence we have tentatively named these compounds as "POMzites" to reflect the POM-based composition and zeolitic nature of each family member, although crucially, POMzites differ from zeolites in the modular manner of their preparation. As the synthesis of further POMzites is anticipated, the classification system and terminology introduced here will allow new compounds to be categorized and understood in the context of the established materials. A better understanding of TM coordination to the {P8W48} ring may allow the targeted synthesis of new frameworks rather than the reliance on serendipity apparent in current methods.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A new mixed solvent procedure which allows the exchange of polyoxometalate (POM) alkali metal cations for tetrabutylammonium (TBA) and protons is presented. This method has been demonstrated for simple Keggin [PW12O40]3− and Dawson [P2W18O62]6− POMs as well as the larger phosphotungstates [Na⊂P5W30O110]14− and [K4⊂P8W48O184]36− for which no TBA salt has been previously reported.

New polyoxometalate 'sandwiches' have been formed where two [P2W15O56](12-)lacunary Dawson clusters encapsulate two transition metal ions to give clusters with the general formula [M-2(II)(P2W15O56)(2)](20-) (where M = Mn, Co, and Ni respectively), [Fe-2(III)(P2W15O56)(2)](18-), and [Cu-4(II)(P2W15O56)2](16-). The Mn, Co, and Ni clusters exhibit a hitherto unseen alpha beta beta alpha isomeric geometry and all five compounds are associated with tetrabutylammonium cations which allow for their dissolution in non-aqueous solvent.

The process of osmotically driven crystal morphogenesis of polyoxometalate (POM)-based crystals is investigated, whereby the transformation results in the growth of micrometer-scale tubes 10-100 μm in diameter and many thousands of micrometers long. This process initiates when the crystals are immersed in aqueous solutions containing large cations and is governed by the solubility of the parent POM crystal. Evidence is presented that indicates the process is general to all types of POMs, with solubility of the parent crystal being the deciding parameter. A modular approach is adopted since different POM precursor crystals can form tubular architectures with a range of large cationic species, producing an ion-exchanged material that combines the large added cations and the large POM-based anions. It is also shown that the process of morphogenesis is electrostatically driven by the aggregation of anionic metal oxides with the dissolved cations. This leads to the formation of a semi-permeable membrane around the crystal. The osmotically driven ingress of water leads to an increase in pressure, and ultimately rupture of the membrane occurs, allowing a saturated solution of the POM to escape and leading to the formation of a "self-growing" microtube in the presence of the cation. It is demonstrated that the growth process is sustained by the osmotic pressure within the membrane surrounding the parent crystal, as tube growth ceases whenever this pressure is relieved. Not only is the potential of the modular approach revealed by the fact that the microtubes retain the properties of their component parts, but it is also possible to control the direction of growth and tube diameter. In addition, the solubility limits of tube growth are explored and translated into a predictive methodology for the fabrication of tubular architectures with predefined physical properties, opening the way for real applications.

An adaptable polyoxometalate macrocycle: The crown-type polyoxometalate [P8W48O184]40− has been prepared in the absence of potassium to give two new mixed lithium/ammonium compounds, allowing cation binding within the heteropolyanion to be investigated. Characterization of binding sites in the {P8W48} cluster could enable prediction of reaction products and selective functionalization of internal and external binding sites.

A design approach for the preparation of the {(DMAH)(7)[H2SbW18O60]} (DMAH-2) and {(DMAH)(7)[H2BiW18O60]} (DMAH-3) (DMAH = dimethylammonium) systems in a highly pure crystalline form is presented, and the latter is characterized by electrospray ionization mass spectrometry (ESI-MS) methods for the first time. These, together with the archetypal [W10O32] cluster, are used as precursors for the formation of unique framework materials incorporating Ag(I) as a linking species. The systems are fully characterized by X-ray crystallography, elemental analysis, IR and thermogravimetric analysis (TGA), and the pyrolysis of the {Ag-4-W10O32} system (1) leads to the formation of silver microparticles embedded in the resulting tungsten oxide and this has been observed by us previously with other systems. In contrast, the carefully controlled decomposition of the antimony and bismuth systems {Ag418O60} (Ag-2) and {Ag-4-SbW18O60} (Ag-3) gives rise to the formation of highly pure, discrete silver microparticles as confirmed by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. These unique materials may be interesting for applications such as catalysis, antimicrobial agents, or electroactive/photoactive coatings, and this work demonstrates how the molecular organization of the building blocks on the nanoscale can affect the assembly of materials over a range of length scales.

Polyoxometalates (POM) are metal oxide cluster compounds with applications in many fields from medicine to nanotechnology. The wide interest and numerous applications mean that the development of POM clusters beyond the traditional molybdenum-, tungsten-, and vanadium-based building blocks is important. The development of polyoxoniobates is still at an early stage and has built upon the isopolyoxoniobate [Nb6O19] 8 ion reported by Lindqvist along with the [Nb10O28] 6 , [Nb20O54] 8 , and [H9Nb24O72] 15 ions. Also, the discovery of the first heteropolyanion, a {Nb12} Keggin-like structure ({[Ti2O2] [SiNb12O40]} 12 ) by Nyman et al. and the recent developments presented by Casey and co-workers demonstrate that Nbbased POMs have great potential. However, the expansion of the field of polyoxoniobates is severely limited by the difficulty in controlling the synthesis. In particular, the narrow window of pH values for solution polyoxoniobate chemistry lies around 10.5–12.5 for reactions under ambient conditions. Given these difficulties, there is a need to develop new approaches to extended polyoxoniobate-based architectures, which is especially important owing to their unique basic properties and potential for catalysis, for example in water splitting. Herein we report the synthesis and structural characterization of two compounds 1 and 2, which contain the polyoxoniobate anions [HNb27O76] 16 (1a) and [H10Nb31O93(CO3)] 23 (2a), respectively. To our knowledge, 1a is the largest isopolyoxoniobate cluster reported to date, while 2a is even bigger than 1 a, but with carbonate ion coordinated on the outside of the cluster; cluster 2a is also intrinsically chiral. Furthermore, structural analysis by single-crystal X-ray crystallography reveals that both of these polyoxoniobates are unprecedented, as they are built from pentagonal {Nb(Nb)5} building units. K13Na3·1a·25H2O (1) and K19Na4·2a·35H2O (2) are prepared in similar syntheses under hydrothermal conditions using K7HNb6O19·13H2O [12] as the precursor in the presence of sodium dibenzyldithiocarbamate. Slow vapor diffusion of methanol into the aqueous solution gave single crystals of K13Na3·1a·25H2O (hexagonal blocks), while K19Na4·2a·35H2O (blocks) is crystallized by slow evaporation of the mother liquor after it was subjected to the hydrothermal conditions. Compound 1 contains the [HNb27O76] 16

Angewandte Chemie International EditionVolume 49, Issue 1 p. 113-116 Communication The Construction of High-Nuclearity Isopolyoxoniobates with Pentagonal Building Blocks: [HNb27O76]16− and [H10Nb31O93(CO3)]23−† Ryo Tsunashima Dr., Ryo Tsunashima Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorDe-Liang Long Dr., De-Liang Long Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorHaralampos N. Miras Dr., Haralampos N. Miras Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorDavid Gabb, David Gabb WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorChullikkattil P. Pradeep Dr., Chullikkattil P. Pradeep Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorLeroy Cronin Prof., Leroy Cronin Prof. l.cronin@chem.gla.ac.uk WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this author Ryo Tsunashima Dr., Ryo Tsunashima Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorDe-Liang Long Dr., De-Liang Long Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorHaralampos N. Miras Dr., Haralampos N. Miras Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorDavid Gabb, David Gabb WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorChullikkattil P. Pradeep Dr., Chullikkattil P. Pradeep Dr. WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this authorLeroy Cronin Prof., Leroy Cronin Prof. l.cronin@chem.gla.ac.uk WestCHEM, Department of Chemistry, The University of Glasgow, University Avenue, Glasgow G12 8QQ (UK), Fax: (+44) 141-330-4888 http://www.croninlab.comSearch for more papers by this author First published: 22 December 2009 https://doi.org/10.1002/anie.200903970Citations: 158 † We thank The Royal Society, EPSRC, WestCHEM and the University of Glasgow for supporting this work. Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Big, bigger, biggest: Polyoxoniobate anions [HNb27O76]16− and [H10Nb31O92(CO3)]23− incorporate pentagonal Nb(Nb)5 building blocks; the central Nb ion is seven-coordinate within the clusters. The Nb27 species was observed using ESI-MS, thus demonstrating some solution stability; the Nb31 species is chiral and incorporates a carbonate ligand in the outer section of the cluster. The two species are the largest polyoxoniobates reported to date. Citing Literature Supporting Information Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Filename Description anie_200903970_sm_miscellaneous_information.pdf1.7 MB miscellaneous_information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article. Volume49, Issue1January 4, 2010Pages 113-116 RelatedInformation

Two cyclic cobalt-substituted heteropolyoxometalates K15Li5[Co-10(H2O)(34)(P8W48O184)]center dot 54H(2)O (1) and K8Li12[Co-10 (H2O)(44)(P8W48O184)]center dot 60H(2)O (2) have been synthesised from the reaction of Co(II) ions and the superlacunary {P8W48} polyanion in mildly acidic aqueous media. The cluster's anion cavities are filled with Co(II) and K cations and careful manipulation of reaction conditions determines the formation of distinct Co-linked frameworks.