Smaller and smaller and more complex – without miniaturization, today we would not have the components needed for high-performance laptops, compact smartphones or high-resolution endoscopes. Research is now being carried out at the nanometric scale on switches, rotors or motors made up of just a few atoms in order to build what are called molecular machines. A research team from the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) has successfully built the world’s smallest energy-powered cogwheel with its matching counterpart. The nano reducer is the first that can also be actively controlled and driven. The researchers’ findings were recently published in the journal natural chemistry.
Miniaturization plays a key role in the further development of modern technologies and makes it possible to manufacture smaller and more powerful devices. It also plays an important role in manufacturing, as it allows materials and functional materials or drugs to be produced at unprecedented levels of precision. Now research has entered the nanometer scale – which is invisible to the naked eye – focusing on individual atoms and molecules. The importance of this new field of research is demonstrated by the Nobel Prize in Chemistry, awarded in 2016 for research on molecular machines.
Some important components used in molecular machines such as switches, rotors, forceps, robot arms or even motors already exist at the nanoscale. Another essential component for any machine is the toothed wheel, which allows changes of direction and speed and allows movements to be linked to each other. Molecular counterparts also exist for cogwheels, however, so far they have only passively back and forth, which is not hugely useful for a molecular machine.
The molecular cogwheel developed by the research team led by Professor Dr. Henry Dube, holder of the Chair of Organic Chemistry I at FAU and previously leader of a junior research group at LMU in Munich, measures only 1 .6nm, which is about 50,000th the thickness of a human hair – the smallest of its kind. But that’s not all. The research team succeeded in actively powering a molecular cogwheel and its counterpart and thus solved a fundamental problem in building nanoscale machines.
The gear unit consists of two components that are interlocked with each other and consist of only 71 atoms. One of the components is a triptycene molecule that is similar in structure to a propeller or bucket wheel (shown in light gray in the animation). The second component is a flat fragment of a thioindigo molecule, similar to a small plate (shown as gold in the animation). If the plate rotates 180 degrees, the propeller only rotates 120 degrees. The result is a 2:3 gear ratio.
The nano gear unit is controlled by light, making it a molecular camera. Directly driven by light energy, the platter and the triptycene propeller move in locked synchronous rotation. Heat alone was not enough to spin the gearbox, as the FAU team discovered. When the researchers heated the solution around the gear in the dark, the propeller spun, but the plate didn’t – the gear “slipped.” The researchers thus came to the conclusion that the nano-gear could be activated and controlled using a light source.
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Material provided by Friedrich-Alexander-Universität Erlangen-Nürnberg. Note: Content may be edited for style and length.