A six-speed molecular gearbox

Benzene-based creation could help to fine-tune nanomachines.

Researchers have created a single molecule with six interlocking gears — which could one day be used as a transmission in a molecular motor.

A team led by Mitsuhiko Shionoya at the University of Tokyo attached six molecules of tryptycene — a compound with three teeth like a paddle wheel — to the edges of a hexagonal benzene molecule. X-ray crystallography confirmed that each of the tryptycene ‘gears’ in this circular arrangement engaged and turned smoothly with its neighbours. The team also threw a molecular spanner into the works in the form of a large, ruthenium-based molecule bonded to one gear. This slowed the gears down such that each turned at a different rate. In the future, this could be exploited to create a transmission that can change gears for molecular motors in nanomachines.