Miniaturization in electronic devices plays a key role in the further development of modern technologies and makes it possible to manufacture smaller devices with more power. One of the major challenges for harnessing the true potential of functional nano-machinery is integrating and transmitting motion with great precision.
Molecular gearing systems enable the integration of multiple motions in a correlated fashion to translate motions from one locality to another and change their speed and direction. However, currently, no powerful methods exist to implement active driving of gearing motions at the molecular scale.
Now, a team of researchers at Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) has successfully built the world’s smallest energy-powered gear wheel with a corresponding counterpart. According to the researchers, the nano gear unit is the first that can be actively controlled and driven.
The molecular gear wheel measures only 1.6 nm, which corresponds to around 50,000ths of the thickness of a human hair – the smallest of its kind. The research team has succeeded in actively powering a molecular gear wheel and its counterpart and has thus solved a fundamental problem in the construction of machines on the nanoscale.
It consists of two components that are interlocked with each other and are made up of only 71 atoms. One component is a triptycene molecule whose structure is similar to a propeller or bucket wheel. The second component is a flat fragment of a thioindigo molecule, similar to a small plate. If the plate rotates 180 degrees, the propeller rotates by only 120 degrees, resulting in a transmission ratio of 2:3.
The nano gear unit is controlled by light, making it a molecular photogear. The plate and the triptycene propeller move in locked synchronous rotation as they are directly driven by the light energy. Heat alone was not sufficient in order to make the gear unit rotate, as the FAU team discovered. When the researchers heated the solution around the gear unit in the dark, the propeller turned, but the plate did not – the gear “slipped.” The researchers thus came to the conclusion that the nano gear unit can be activated and controlled using a light source.