Researchers in France have made an interlocked network of molecules that they say brings complex molecular machines a step closer.  

Jean-Pierre Sauvage and colleagues at the University Louis Pasteur in Strasbourg created a two-dimensional interlocked network known as a pseudo-rotaxane.  The structure consists of two handcuff-shaped molecules (called bis-macrocycles) threaded onto two rod-shaped molecules.

Rotaxanes are interlocking molecules with molecular stoppers on each end to hold the molecules in place.  Pseudo-rotaxanes don't have any stoppers.  The key to the stability of Sauvage's pseudo-rotaxanes is copper ions that bind to specific parts of the bis-macrocycles and rods, holding them in a rigid arrangement.

Sauvage said the copper ions have the effect of collecting together the components and helping them to interlock, providing a simple way to obtain a complicated product.

David Leigh, an organic chemist at the University of Edinburgh, said that the work 'describes highly effective methodology for threading two "double binding site" rods through two "double holed" rods to form a well-defined molecular rectangle with interpenetrated sides.' 

Sauvage said the pseudo-rotaxane could have applications in nanotechnology.  'The present system represents a first step towards complex molecular machines containing two, or several, mobile parts,' he said.

Rachel Warfield