Synthetic molecular motors have been inspired by ATP synthase, an enzyme present in cell membranes, which exhibits complex and controlled rotary motion while converting electrical energy to chemical energy.

Rapenne is developing single molecules based on wheelbarrows, gears and motors. The various parts of these molecules can be made to move under the control of a microscope tip. Rapenne has demonstrated her example of a motor made from a fixed aromatic platform surrounded by five arms containing groups that move under the influence of an electron current.

Practical applications for these molecular machines have yet to materialise because of difficulties in making systems rigid enough to exploit their movement. Research is in progress to overcome these problems.

Suzanne Abbott