JST Press Release

July 19, 2019

Japan Science and Technology Agency (JST)
5-3, Yonbancho, Chiyoda-ku, Tokyo

Molecular Nanocarbons with Mechanical Bonds

The generation of topologically complex nanocarbons can spur developments in science and technology. However, conventional synthetic routes to interlocked molecules require heteroatoms.

A team led by Dr. Yasutomo Segawa and Professor Kenichiro Itami of the JST- ERATO Itami Molecular Nanocarbon Project and the Institute of Transformative Bio-Molecules (ITbM) reports the synthesis of catenanes and a molecular trefoil knot consisting solely of para-connected benzene rings. Characteristic fluorescence of a heterocatenane associated with fast energy transfer between two rings was observed, and the topological chirality of the all-benzene knot was confirmed by enantiomer separation and circular dichroism spectroscopy. The seemingly rigid all-benzene knot has rapid vortex-like motion in solution even at -95°C, resulting in averaged nuclear magnetic resonance signals for all hydrogen atoms. This interesting dynamic behavior of the knot was theoretically predicted and could stimulate deeper understanding and applications of these previously untapped classes of topological molecular nanocarbons.

Program Information

JST ERATO Itami Molecular Nanocarbon project
Research Area “Molecular Nanocarbon”

Journal Information

Yasutomo Segawa, Motonobu Kuwayama, Yuh Hijikata, Masako Fushimi, Taishi Nishihara, Jenny Pirillo, Junya Shirasaki, Natsumi Kubota, Kenichiro Itami. “Topological molecular nanocarbons: all-benzene catenane and trefoil knot”,
journal, Science, published online July 19, 2019, DOI: 10.1126/science.aav5021