Mimicking oxide surfaces: different types of defects and ligand coordination at well defined positions of a molybdenum oxide based nanocluster

The mixed valence cluster anion of the compound (NH4)32[MoVI110MoV28O416H6(H2O)58(CH3CO2)6].xH2O 1 (x approximately 250), synthesized under one-pot conditions, contains well-defined different types of defects--missing groups compared to the complete parent (Mo154) type cluster with full D7d symmetry--and acetate ligand coordination; this proves that the giant-wheel type anion can be considered as an object with a variety of nanoscale structural features ("nanostructured landscape") allowing reactions at a variety of well defined centers.     

Archimedean Synthesis and Magic Numbers: "Sizing" Giant Molybdenum-Oxide-Based Molecular Spheres of the Keplerate Type

Pythagorean harmony can be found in the spherical polyoxometalate clusters described here (see illustration for an example of a structure), since there are interesting relationships between the so-called magic numbers (12, 32, 42, 72, 132) relevant for spherical viruses and the number of the building blocks in the cluster. The size of these Keplerate clusters can be tailored by varying the type of connections between the pentagons by means of different spacers.     

Dynamic Light Scattering Evidence for a Ligand-Induced Motion between the Two Domains of Glucoamylase G1 of Aspergillus niger with Heterobivalent Substrate Analogues

Heterobifunctional ligands that bind at the same time to the catalytic domain and to the starch-binding domain of glucoamylase induce a conformational change of the protein, as shown by dynamic light scattering. The ligands consist of acarbose and β-cyclodextrin linked together by oligoethylene glycols of variable length (see the schematic diagram).     

Formation of a Ring-Shaped Reduced “Metal Oxide” with the Simple Composition [(MoO3)176(H2O)80H32]

The largest inorganic molecular system so far , [(MoO₃)₁₇₆(H₂O)₈₀H₃₂] ( 1 ; the picture on the right shows the polyhedral representation), which has been characterized by X-ray structure analysis, possesses a cavity of diameter 2.3 nm and remarkably shows the stoichiometry of a (reduced) protonated and hydrated “molecular molybdenum trioxide”. It is formed by reduction of an aqueous solution of lithium molybdate with tin(II ) chloride at very high H⁺ concentrations.     

Organizational Forms of Matter: An Inorganic Super Fullerene and Keplerate Based on Molybdenum Oxide

Plato and Kepler would have been pleased . Despite the large number of atoms present the cluster anion 1 resembles an icosahedral-type structure. This represents definitively an unprecedented event in chemistry! The structure is made up of 12 {Mo₁₁} fragments such that the fivefold symmetry axes are retained in the resulting spherical object. As an inscribed icosahedron can be recognized in the spherical shell of 1 (see picture), similarities with Kepler's famous shell model of the cosmos can be seen.     

Heterobinuclear complexes as building blocks in designing extended structures

The heterobinuclear complex [CuPrL(NO(3))(3)] has been used as a building block for the construction of a two-dimensional coordination polymer with the formula [CuPrL(NO(3)(2)(IN)], 1 (L(2-) = the dianion of the compartmental Schiff-base ligand obtained from the 2:1 condensation of 3-methoxysalicylaldehyde with 1,3-propanediamine; IN(-) = the isonicotinate ion). The heterobinuclear units, [CuPrL(NO(3))(2)](+), are connected through the unsymmetrical exo-bidentate ligands, IN(-), leading to a unique extended structure. Crystal data for compound 1: FW, 790.94; monoclinic, space group P2(1)/n, a = 11.2837(3) A, b = 14.7785(4) A, c = 16.9745(4) A, beta = 100.427(1) degrees; V = 2783.86(12) A(3); Z = 4; R1 = 0.0210, wR2 = 0.0562 [I > 2sigma(I)].