Gold-plated nanodiamonds could combine the characteristics of gold and diamond to give unique physico-chemical properties, according to a computational chemist.

Fedor Naumkin at the University of Ontario Institute of Technology, Canada, used computer calculations to model the stability and structure of a cluster of five carbon atoms surrounded by a shell of twelve gold atoms (C₅Au₁₂). 'Nanometre-sized aggregates of atoms (clusters) have properties of both scientific and technological interest, for example in creating new catalysts,' said Naumkin. 'The cluster considered here represents an attempt to combine the catalytic power of gold with the mechanical strength of diamond.' 

Naumkin's calculations suggested that the predicted stability of the cluster, compared to its dissociation into a C₅ unit and twelve separate gold atoms, was high enough to favour its formation, perhaps in a mixture of laser-evaporated carbon and gold. But the efficiency of producing the desired structure under such conditions is 'an open issue' and the synthesis of such systems may prove difficult, Naumkin cautioned. 

Pekka Pyykkö, professor of chemistry at the University of Helsinki, Finland, has research interests in computational studies of heavy elements. 'Although C₅Au₁₂ may be too fragile and reactive to synthesise, Naumkin raises an interesting question about what kinds of structures can be formed by combining tetrahedrally coordinated carbon atoms and gold,' said Pyykkö.

Naumkin plans to continue studying this type of cluster, changing the size and composition and investigating the way the clusters interact with other molecules. 

Susan Batten