The new tungstogermanate: Tungsten atoms: black, Cerium atoms: orange, Germanium atoms: green,WO6-octahedrons: light blue
Ulrich Kortz, Professor of Chemistry at Jacobs University, and his team successfully synthesized a polyoxometalate with 100 Tungsten and 20 Cerium atoms that has a molar mass of about 30 kilo Dalton. With a maximum diameter of 4.2 nm the inorganic molecule is comparable in size to large complex bio-molecules or even small viruses.
Polyoxometalates are anionic metal-oxygen clusters of large structural diversity with chemical properties, which make them especially interesting for applications in catalysis, but also in materials science and nanotechnology.
Ulrich Kortz and his co-workers now achieved the synthesis of the tungstogermanate*, which belongs to the polyoxometalates, by condensation of the precursors [α-GeW9O34]10- and Cerium(III) ions in aqueous solution.
With about 600 atoms in total, amongst them 100 atoms of the heavy metal Tungsten, the new compound is the third largest molecular polytungstate ever synthesized. In addition it contains the largest number of atoms of the Rare Earth Cerium ever incorporated in such a compound.
"A single molecule of our new giant tungstate has many catalytically active centers and therefore a very high catalytic potential, which normally applies only to biological catalyst molecules. Being a lot less temperature and oxidatively sensitive than bio-catalysts though and in crystalline form applicable as a heterogenic solid catalyst in liquid phase reactions our new tungstogermanate is predestined for industrial purposes," says Ulrich Kortz about the possible applications of the newly created molecule.
"In addition our successful synthesis allows very good inferences about the mechanism of formation by stepwise self-assembly of the simple precursors in a classic one-pot synthesis, which is vitally important for the development of other so-called 'molecular machines', large molecules designed to have very specific functions," the Jacobs chemist concludes.
*Tungstogermanate [Ce20Ge10W100O376(OH)4(H2O)30]56-
The reaction conditions and the molecular structure were published in Angewandte Chemie (doi: 10.1002/anie.200701422).
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