The construction of structurally homogeneous nanocarbons is crucial for the development of functional materials in nanotechnology, electronics, optics, and biomedical applications. According to a paper recently published in the journal “Nature Synthesis”, a research team from Nagoya University in Japan has synthesized a ribbon-like molecular nanocarbon with a twisted Möbius ribbon topology, namely Möbius carbon nanoribbons.
Molecular nanocarbon science is a bottom-up approach to manufacturing nanocarbons using synthetic organic chemistry. However, molecular nanocarbons synthesized so far only have simple structures such as rings, bowls or ribbons. To realize the unknown and theoretically predicted nanocarbons, it is necessary to develop new methods to synthesize molecular nanocarbons with more complex structures.
In 2017, a Nagoya University research team chemically synthesized carbon nanoribbons, a type of ultra-short carbon nanotubes, for the first time in 60 years. After that, Mobius carbon nanoribbons became the coveted target of the scientific community.
“Such twisted Möbius carbon nanoribbons should exhibit completely different properties and molecular motions than those with normal ribbon topology. However, creating such twisted structures is easier said than done.” Research team leader Kenichiro Itami said that from previous carbon nanoribbon synthesis, strain energy was the biggest obstacle in the synthesis process. Furthermore, the extra twist within the ribbon structure makes the strain energy of the final target molecule higher.
Through theoretical analysis of the huge strain generated by the ribbon-like and twisted molecular structure of Möbius carbon nanobelts, the research team determined a reasonable synthesis route, and finally synthesized Möbius carbon nanobelts through 14 chemical reaction steps, These include newly developed functionalization reactions, Z-selective Wittig reaction sequences, and strain-induced nickel-mediated homologous coupling reactions. Spectroscopic analysis and molecular dynamics simulations show that in solution, the twisted part of the Möbius ribbon moves rapidly around the Möbius carbon nanoribbon molecules in solution. Using chiral separation and circular dichroism spectroscopy, the topological chirality of the Möbius structure was experimentally confirmed.
New forms of carbon and nanocarbons continue to open doors for new technologies and lead to the discovery of often unpredictable extraordinary properties, functions and applications, the researchers say. This work paves the way for the development of nanocarbon materials with complex topologies and the birth of innovative materials science using Möbius topology.