Study measures single-molecule machines in action

In the development of future molecular devices, new display technologies, and "artificial muscles" in nanoelectromechanical devices, functional molecules are likely to play a primary role.

Rotaxane, showing movement of ring to different stations along the rod

Rotaxanes, one family of such molecules, are tiny, mechanically interlocked structures that consist of a dumbell-shaped molecule whose rod section is encircled by a ring.

These structures behave as molecular "machines," with the ring moving along the rod from one station to another when stimulated by a chemical reaction, light or acidity.

To realise the potential of these molecular machines, however, it is necessary to understand and to measure their function at the nanoscale.

Previous methods for observing their operation have involved chemical measurements in solution and studying collections of them attached to surfaces, but neither has provided an accurate picture of their function in environments that are relevant to molecular-device operation.

Now, a multidisciplinary team of researchers from UCLA, Northwestern University, UC Merced, Pennsylvania State University and Japan has succeeded in observing single-molecule interactions of bistable rotaxanes functioning in their native environment.