Researchers have created a molecule with a novel topology resembling a half-Möbius strip, requiring four loops to return to the starting point. The structure, made from 13 carbon atoms and two chlorine atoms, was assembled on a gold surface at low temperatures. This discovery highlights potential advances in molecular engineering and quantum simulations.
Chemists led by Igor Rončević at the University of Manchester in the UK have developed a molecule exhibiting an unprecedented "half-Möbius" shape, which is described as twice as unusual as the traditional Möbius strip. The Möbius strip, a looped band with a single twist, requires traversing the loop twice to return to the starting side. In contrast, this new molecule demands four full circuits for a quantum particle to complete its path back to the origin.
The molecule consists of a ring formed by 13 carbon atoms and two chlorine atoms, constructed on a thin gold surface under extremely cold conditions. Specialized tools, including an atomic force microscope and a scanning tunnelling microscope, were employed to position the atoms and examine electron properties. Electrons in this structure delocalize across the ring, behaving like waves and generating the distinctive twist through their interactions.
Rončević noted, “This molecule is very new and very unexpected. The appeal is not just that we made a molecule with an unusual topology, but we also showed that this topology is possible, and no one really thought about it.”
Applying a small electromagnetic pulse allowed the team to alter the molecule's handedness from left to right or remove the twist entirely, demonstrating on-demand topological control. To validate the structure, simulations were run on both conventional computers and an IBM quantum computer. Ivano Tavernelli at IBM emphasized, “This is an example of how quantum computers can already be useful for real-world chemistry problems,” particularly for modeling complex electron interactions.
Experts praised the work. Gemma Solomon at the University of Copenhagen called it “a remarkable achievement across a number of dimensions: organic chemistry, surface science, nanoscience and quantum chemistry.” Kenichiro Itami at RIKEN described it as “a beautiful and inspiring study that brings abstract topological concepts vividly into the realm of molecular chemistry,” labeling it a technical tour de force. Dongho Kim at Yonsei University highlighted the switching capability's potential for sensor applications, such as responses to magnetic fields.
The findings appear in Science (DOI: 10.1126/science.aea3321).