Representation of the electrons in the “half-Möbius” shaped molecule
IBM Research and the University of Manchester
Chemists have discovered a new molecular shape, and it’s twice as weird as the twisted Möbius strip.
The Möbius strip is a looped strip with a twist so that something tiny, such as an ant, has to go around the loop twice to return to where it started on the same side of the strip.
Igor Rončević at the University of Manchester in the UK and his colleagues have now discovered a molecule with an even stranger “half-Möbius” shape. Their experiment could be the first step toward a new way to engineer useful molecules by adjusting their 3D shapes, or topology.
“This molecule is very new and very unexpected. The appeal is not only that we made a molecule with an unusual topology, but we also showed that this topology is possible, and no one has really thought about it,” he says.
To create the molecule, the researchers used 13 carbon atoms and two chlorine atoms assembled into a ring-like shape on a thin surface of gold at an extremely cold temperature. They used two specialized microscopes – an atomic force microscope and a scanning tunneling microscope – to inspect the atoms and map the properties of their electrons. In this type of molecule, the electrons are not tightly bound to their atoms; instead, the electrons spread over specific areas around the atoms like little waves of matter.
It was the interactions between these electrons that gave the never-before-seen twist in the molecule. If a tiny quantum creature traveled along the atoms, it would take four circuits of the ring to return to its starting point.
By pushing the molecule with a small electromagnetic pulse, the team was able to switch the molecule’s twist from left-handed to right-handed, or to twist it up. The researchers could engineer the topology as needed, creating another way for chemists to manipulate molecules.
To understand the new molecule and why it could even exist, the team used simulations on both a conventional computer and an IBM quantum computer. Interactions between electrons were crucial to the molecule’s new twists, and they are difficult to simulate accurately with conventional computers. But quantum computers are already built from interacting quantum objects, so they can perform simulations at a higher level of confidence, says Rončević.
This is an example of how quantum computers can already be useful for real-world chemistry problems, says team member Ivano Tavernelli at IBM.
“This experiment is a remarkable achievement across a number of dimensions: organic chemistry, surface science, nanoscience and quantum chemistry,” says Gemma Solomon of the University of Copenhagen in Denmark.
“This is a beautiful and inspiring study that brings abstract topological concepts alive into the realm of molecular chemistry,” says Kenichiro Itami of the Japanese scientific institute RIKEN. He says the study is a technical one tour de force.
Dongho Kim of Yonsei University in South Korea, a pioneer in earlier work on Möbius-like molecules, says being able to switch the molecule from one shape to another is particularly interesting, as it could lead to use in sensors. For example, molecules can switch in a pre-programmed way when exposed to magnetic fields.
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