Molecular motor goes both ways

University of Edinburgh researchers have constructed a molecular motor that can spin in either direction, much like the biological molecular motors involved in many of life's processes.

The motor consists of a pair of interlocking rings; the smaller ring travels clockwise or counterclockwise around the larger ring depending on the order in which several chemical reactions are carried out on the molecule.

The motor could eventually be used in nanotechnology applications like nanomechanical computers and molecular assembly.

The motor's smaller ring attaches to one of two docking sites on the larger ring. Both paths between docking stations are blocked. Shining ultraviolet light on the molecule trips off a chemical reaction that releases the smaller ring from the first docking site. Once released, the smaller ring is inclined by ever-present Brownian molecular motion to move around the larger ring.

A second chemical reaction removes the block on the desired side to allow the smaller ring to travel 180 degrees around the larger ring and connect to the second docking station.

A chemical catalyst releases the smaller ring from its second docking place; when the block is chemically released the ring moves back to its original position.

To be practical, the motor must rotate much more quickly, and the rotation mechanisms must be simplified. Proof-of-concept molecular motors take minutes or hours to rotate. Practical motors would have rotations measured in milliseconds, or thousandths of a second. The researchers' molecular motor requires four inputs in the form of light, heat or chemicals to complete a rotation. Ideally the motors would be driven by light or electricity.

The molecular motor could be ready for practical use in 10 years, according to the researchers. The work appeared in the November 25, 2004 issue of Science.