• selfassembly processes of nanoobjects with hydrophilic surfaces leading to unprecedented vesicles,

• exchange reactions at surfaces of minerals,

• templated construction of materials under confined conditions,

• special problems of single molecular magnets,

• water molecule assemblies under confined conditions.

Work/publications of other groups based on the mentioned nanoobjects, for example (see also Molecular Magnetism):

"Synthesis of Orthorhombic Mo-V-Sb Oxide Species by Assembly of Pentagonal Mo₆O₂₁ Polyoxometalate Building Blocks"
M. Sadakane et al. (Angew. Chem. Int. Ed. 2009, 48, 3782).

Figure and text from the graphical abstract

"Mix and match: The pentagonal [Mo₆O₂₁]^n- polyoxomolybdate building block assembles with other sources of Mo, V, and Sb ions to form an orthorhombic Mo-V-Sb oxide. The first single-crystal X-ray analysis of an orthorhombic Mo-V-based oxide, a promising catalyst for light alkane selective oxidation known as the "M1 phase" revealed the structure of the compound."

See also related frontispiece:

"Structural Link between Giant Molybdenum Oxide Based Ions (e.g. our Keplerates) and Derived Keggin Structure: Modular Assemblies Based on the [BW₁₁O₃₉]^9- Ion and Pentagonal {M'M₅} Units (M' = W; M = Mo, W)"
N. Leclerc-Laronze, J. Marrot, R. Thouvenot, E. Cadot (Angew. Chem. Int. Ed. 2009, 48, 4986).

Text:
"Actually, until the beginning of the 1990s, this wide class of compounds was dominated by a few structural archetypes, namely, the Lindqvist, Keggin, and Dawson anions. From 1994, Müller has advanced the knowledge of polyoxometalate chemistry with numerous reports on unprecedented nanosized arrangements based on molybdenum oxide clusters. These topological structures are characterized by a striking pentagonal building unit {Mo(Mo₅)}, which condenses with metal cations to form either spheroidal capsules (keplerate) or wheel-shaped clusters."

From the Graphical Abstract

	Linked to the Pentagon: The addition of molybdate to [HBW11O19]8- ions leads to the formation of mixed pentagonal units {W(Mo5)} and {W(WMo4)} trapped as linkers in the resulting modular assemblies, thus establishing the first link between the conventional Keggin ions derivatives and the giant molybdenum oxide and keplerate ions.

• Studies based on materials obtained by encapsulations in cationic surfactants; this refers to the construction of nanostructures at interfaces (I), of liquid crystals (II) as well as of LB films and monolayers (III).

Related Publications:

(I) "Self-Patterning of Hydrophobic and Highly Ordered Honeycomb Nanostructures at the Air/Water Interface"
D. Fan, X. Jia, P. Tang, J. Hao, T. Liu (Angew. Chem. Int. Ed. 2007, 46, 3342).



SEM images of highly ordered honeycomb architectures of {Mo₇₂Fe₃₀}-DODMA complexes.
(II) a) "Colloidal Organization and Clusters: Self-Assembly of Polyoxometalate-Surfactant Complexes towards Three Dimensional Organized Structures"
S. Polarz, B. Smarsly, M. Antonietti (ChemPhysChem 2001, 2, 457).




b) "Evidence of ionic liquid crystal properties for a DODA⁺ salt of the keplerate [Mo₁₃₂ O₃₇₂(CH₃COO)₃₀(H₂O)₇₂]^42-"
S. Floquet, E. Terazzi, A. Hijazi, L. Guénée, C. Piguet, E. Cadot (New J. Chem. 2012, 36, 865).





Liquid crystalline organization of clusters DODA-Mo₁₃₂. (a) View parallel to the layers illustrating the long range layered organization. (b) View perpendicular to the layers highlighting the local hexagonal packing.



(III) "Langmuir-Blodgett Films of a Mo-Blue Nanoring [Mo₁₄₂O₄₂₉H₁₀(H₂O)₄₉(CH₃ CO₂)₅(CH₃CH₂CO₂)]^30- (Mo₁₄₂) by the Semiamphiphilic Method"
M. Clemente-León, T. Ito, H. Yashiro, T. Yamase, E. Coronado (Langmuir 2007, 23, 4042).


See also:
"Nanoscale Assemblies of Gigantic Molecular {Mo₁₅₄}-Rings: (Dimethyldioctadecylammonium)₂₀[Mo₁₅₄O₄₆₂ H₈(H₂O)₇₀]"
T. Akutagawa, R. Jin, R. Tunashima, S.-i. Noro, L. Cronin, T. Nakamura (Langmuir 2008, 24, 231).

"Metallo-supramolecular modules as a paradigm for materials science"
D. G. Kurth (Sci. Technol. Adv. Mater. 2008, 9, 014103).





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• Construction of hybrid materials obtained by sol-gel processes, while the clusters' integrities as well as reactivities are maintained.

Publication:
"The Interplay of Colloidal Organization and Oxo-Cluster Chemistry: Polyoxometalate-Silica Hybrids - Materials with a Nanochemical Function"
S. Polarz, B. Smarsly, C. Göltner, M. Antonietti (Adv. Mater. 2000, 12, 1503).




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• Study of cation transport through inorganic membranes/vesicles formed from {Mo₇₂Fe₃₀} Keplerates.

Publication:
"Membranes Based on "Keplerate"-Type Polyoxometalates: Slow, Passive Cation Transportation and Creation of Water Microenvironment"
P. P. Mishra, J. Pigga, T. Liu (J. Am. Chem. Soc. 2008, 130, 1548).





Important in the context: A theoretical study of the formation/stabilization mechanisms of the mentioned new type of vesicles.

See also: "Lag Periods During the Self-Assembly of {Mo₇₂Fe₃₀} Macroions: Connection to the Virus Capsid Formation Process"
J. Zhang, D. Li, G. Liu, K. J. Glover, T. Liu (J. Am. Chem. Soc. 2009, 131, 15152).

Publication:
"Charge Regulation as a Stabilization Mechanism for Shell-Like Assemblies of Polyoxometalates"
W. K. Kegel et al. (Phys. Rev. Lett. 2007, 99, 066104:1-4).


Abstract: "We show that the equilibrium size of single-layer shells composed of polyoxometalate macroions is inversely proportional to the dielectric constant of the medium in which they are dispersed. [...] This observation points to a new class of thermodynamically stable shell-like objects. We point out the possible relevance our findings have for certain surfactant systems."


Related figures taken from the mentioned publication:



Fig. 1 Polyoxometalates Mo72Fe30 (top, left) and Mo132 (bottom, left) and a cartoon of their shell-like superstructure where the size range refers to the situation in aqueous solutions.	Fig. 2 Shell radius as determined by dynamic light scattering as a function of the inverse relative dielectric constant of the solvent (water, methanol, ethanol, propanol, acetone, acetone-water mixtures) for two different polyoxometalates: Mo72Fe30 and Mo132.

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• Preparation of unprecedented supramolecular compounds.




Publication:
"Directed 1D Assembly of a Ring-Shaped Inorganic Nanocluster Templated by an Organic Rigid-Rod Molecule: An Inorganic/Organic Polypseudorotaxane"
M. A. Alam, Y.-S. Kim, S. Ogawa, A. Tsuda, N. Ishii, T. Aida (Angew. Chem. Int. Ed. 2008, 47, 2070).



See also: "A Molybdenum Crown Cluster Forms Discrete Inorganic-Organic Nanocomposites with Metalloporphyrins"
A. Tsuda, E. Hirahara, Y.-S. Kim, H. Tanaka, T. Kawai T. Aida (Angew. Chem. Int. Ed. 2004, 43, 6327).




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• Separation of {Mo₇₂Fe₃₀}-embedded nanocapsules which could be aligned in a magnetic field (though {Mo₇₂Fe₃₀} is a paramagnetic molecule).
Publication:
"Magnetic {Mo₇₂Fe₃₀}-embedded hybrid nanocapsules"
J. Cui, D. Fan, J. Hao (J. Colloid and Interface Science 2009, 330, 488).

Related figures taken from the publication:



Scheme 1: Illustration of the LbL assembly of PAH, PSS and POM ({Mo72Fe30}) on PSA particles and hollow microcapsules. The first stage (a-b) involves stepwise deposition of PE on PSA colloidal particles. (b-e) Alternative assembly PAH and {Mo72Fe30} nanoparticles. (e-f) Decomposition of PSA cores and formation of hollow [(PAH/PSS)2(PAH/{Mo72Fe30})6PAH] microcapsules.	Fig. 6 TEM image of {Mo72Fe30}-embedded nanocapsules aligned in an external magnetic field.

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• Modeling of water ligand exchange rates on mineral surfaces with relevance for geochemical aspects.

Publication:
"Minerals as Molecules - Use of Aqueous Oxide and Hydroxide Clusters to Understand Geochemical Reactions"
W. H. Casey, J. R. Rustad, L. Spiccia (Chem. Eur. J.. 2009, 15, 4496).






Figure 11: The molecule Mo₇₂Fe₃₀ with thirty >Fe^III - OH₂ was intended to shed light on the rates of ligand substitution in ferric hydroxide soil minerals, like the goethite structure shown, which also have isolated >Fe^III - OH₂. Balogh et al. examined earlier (see below) the rates of water exchange on a Keplerate molecule that had thirty >Fe^III - OH₂ functional groups accessible to the bulk aqueous solution.

"This molecule has 30 exterior-bound water molecules or >Fe^III - OH₂ functional groups, which are isolated from one another, as are the water molecules bound to the mineral" (p. 4509, left column)

See also: "Rates of Ligand Exchange between >Fe^III - OH₂ Functional Groups on a Nanometer-Sized Aqueous Cluster and Bulk Solution"
E. Balogh, A. M. Todea, A. Müller, W. H. Casey (Inorg. Chem. 2007, 46, 7087)


"With this molecule, one can illuminate some pressing questions about ligand-exchange rates in subcoloidal Fe(III) oxyhydroxide materials, such as whether the rates scale with bond lengths and if deprotonation of some of the isolated waters affects the reactivities of those that remain" (p. 7087, right column).




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• The Mo₁₅₄ and Mo₁₇₆ type "big-wheels" have unique surface and structure properties. Some of these are reported in the following.

Publication:
"Adsorption and Catalytic Properties of the Inner Nanospace of a Gigantic Ring-Shaped Polyoxometalate Cluster"
S.-i. Noro, R. Tsunashima, Y. Kamiya, K. Uemura, H. Kita, L. Cronin, T. Akutagawa, T. Nakamura (Angew. Chem. Int. Ed. 2009, 48, 8703).




From the Graphical Abstract

	Functional inner space: A gigantic ring-shaped {Mo154} polyoxometalate cluster anion can be stabilized by encapsulation in dimethyldioctadecylammonium (DODA) cations. Its inner nanospace enables adsorption of gases and vapors, and it acts as a water-tolerant solid acid catalyst .

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• In context with our interest for the preferable formation of spherical structures we wrote in the abstract of a related paper:
  
  "A novel and fundamental reaction system of matter following a type of 'supramolecular Darwinism' leads to the formation of giant spherical nano-sized cluster capsules as kinetically controlled destination having the highest possible symmetry (I_h) and formed directly from the decomposition products of the well known but less symmetrical Keggin anions (T_d) in aqueous medium in the presence of Fe^III - acting as a type of environmental influence - under conditions where Keggin anions are known to be extremely stable; remarkably the remaining non-decomposed Keggin anions finally get (non-covalently) encapsulated protected by the formed spherical capsules of a new type (of supramolecular compound...)" This is highlighted in the following.

Publication:

"From supramolecular chemistry towards constitutional dynamic chemistry and adaptive chemistry"
J.-M. Lehn (Chem. Soc. Rev. 2007, 36, 151).




We read: "Such a self-optimisation (the formation of guanine quartet-based hydrogels) behaviour may be of broader significance, namely for prebiotic chemical evolution, whereby selection is driven by phase cohesion, the entity selected being that giving the most stable organised supramolecular assembly in a sort of prebiotic Darwinism driven by self-organisation. The supramolecular organisation drives the selection of the components giving the " fittest" constituent."⁶⁰ (Ref. 60: For systems presenting a type of supramolecular Darwinism, see: A. Müller, S. K. Das, H. Bögge, M. Schmidtmann, A. Botar, A. Patrut, Chem. Commun. 2001, 657).

Title of our original paper: "Generation of cluster capsules (I_h) from decomposition products of a smaller cluster (Keggin-T_d) while surviving ones get encapsulated: species with core-shell topology formed by a fundamental symmetry-driven reaction".








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• Regarding catalytic properties of Mo₇₂ Fe₃₀ Keplerates.

Publications:
(I) "Catalytic properties of the macromolecular polyoxomolybdate cluster in selective oxidation of sulfides"
N. V. Izarova, O. A. Kholdeeva, M. N. Sokolov, V. P. Fedin (Russ. Chem. Bull., Int. Ed. 2009, 58, 134-137).

(II) "CVD growth of carbon nanotubes using molecular nanoclusters as catalyst"
K. Goss, A. Kamra, C. Spudat, C. Meyer, P. Kögerler, C. M. Schneider (Phys. Status Solidi B 2009, 246, 2494-2497).


   

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General Literature (Reviews): A. Proust, R. Thouvenot, P. Gouzerh, "Functionalization of polyoxometalates: towards advanced applications in catalysis and materials science", Chem. Commun. 2008, 1837 (see sections "Introduction" and "Nanosized polyoxomolybdates with multifunctionality"); A. Müller, S. Roy , "Multifunctional metal oxide based nanoobjects: spherical porous capsules/artificial cells and wheel-shaped species with unprecedented materials properties", J. Mater. Chem. 2005, 15, 4673; A. Müller, S. Roy, "Linking Giant Molybdenum Oxide Based Nano-Objects Based on Well-Defined Surfaces in Different Phases", Eur. J. Inorg. Chem. 2005, 3561; D.-L. Long, L. Cronin, "Towards Polyoxometalate-Integrated Nanosystems", Chem. Eur. J. 2006, 12, 3698; P. Gouzerh, M. Che, "From Scheele and Berzelius to Müller: Polyoxometalates (POMs) revisited and the "missing link" between the bottom up and top down approaches", L'Actualité Chimique 2006, June Issue, p. 9; A. Müller, S. Roy, in "The Chemistry of Nanomaterials: Synthesis, Properties and Applications" (Eds.: C. N. R. Rao, A. Müller, A. K. Cheetham), Wiley-VCH, Weinheim 2004, p. 452.