German researchers have constructed an artificial cell using an inorganic macromolecule, a spherical polyoxymolybdate cluster, rather than the more usual organic and protein components associated with cell membranes. NMR played a key role in tracking their progress towards this system and has shed let on the properties of the resulting complex.

A little imagination and a lot of experience with inorganic macromolecules has allowed Achim Mueller of the University of Bielefeld, Germany, and his colleagues to construct what they describe as an "artificial cell" from a cluster of augment molybdenum atoms. They explain how their molybdenum cell has twenty circular pores, each surrounded by an alternating series of nine molybdenum and nine oxygen atoms. Each pore has a non-covalently bonded urea "stopper". The presence of doubly charged sulfate groups covalently bonded to the interior of the cell endow it with a large overall negative charge. The team has also shown that the artificial cell is partially filled with water molecules and ⁹⁵Mo NMR and Raman spectroscopy was used to demonstrate its stability and the complex's water solubility.

Mueller explains that this artificial cell is a proof of principle and that the general methodology could be used to develop "revolutionary applications" in chemistry, for instance in modelling passive ion transport through real cell membranes, in materials science for the construction of a nanoscale ion chromatograph, for instance, in physics studies of confined matter, and even in mathematics in the investigation of tiling of spheres as well as the construction of interpenetrating (semi)regular solids).

Related links:

• Angew Chem Int Edn, 2005, in press
• J. Mater. Chem., 2005, 4673-4677
• Mueller Website

Article by David Bradley