The Dynamics of Molecular Gears

  • Ken’s lab investigates pericyclases and the 6 + 4 reaction. Dr. Houk was brought into the molecular machines field by his colleage Fraser Stoddart when they did some work on a linear motor molecule. He is now interested in amphidynamic materials – materials with a high level of molecular order and molecular motion.
  • Triptycenes are used in spur gears – gears with opposing rotation. This is how gears normally work, but unfortunately in the molecular world sometimes there is gear slipping. Dr. Jay Siegel had originally built a 3 toothed gear using triptycenes, and this design was improved upon by the Jiang-Jellen-Jin group by anchoring both sides of the gear.
  • Another version made by shiyonoya et. al. is a 4 rotor gear that operates much like a bevel gear. Various ligands can be used for the attachment points, which alters rotation speed as measured by dynamic NMR.

Molecular gear dynamics – an illustration of the problems for 3 pronged gears regarding slippage and gearing states


  • Building a 4+ toothed molecular gear. A 4 toothed gear has not been made yet. The low number of teeth leads to low gearing fidelity. Currently, these gears operate on random brownian motion, but it is necessary to transition to continuous directional motion in order to extract work from molecular gear sets.

  • Building practical molecular gears – incorporating molecular gears and rotors into metal organic frameworks to create a response to external simulus such as magnetic fields. This has applications for visual displays, sensors, gyroscopes, motors, and levers with magnetic or electric fields.