Major Breakthrough Creates First-Ever Cyclocarbon, a Ring of Pure Carbon Atoms

Researchers have finally synthesized the elusive cyclocarbon, the theoretical molecule whose structure holds the potential for many novel and important properties for science and industrial applications.
John Loeffler
IBM Research

Researchers have finally created an important molecular structure, the cyclocarbon, that had stubbornly eluded the efforts of chemists to synthesize for more than 50 years and which may hold the key to creating molecular-scale semiconductors with a variety of scientific and industrial applications.

Scientists synthesize ring of pure carbon atoms, creating first-ever cyclocarbon

For decades, chemists have tried and failed to successfully create a proposed structure for carbon molecules that they knew was possible, but which proved aggravatingly hard to create. The closest anyone ever came was to find evidence for these structures in reactive gases, but this reactively prevented them from being isolated and confirmed. Now, researchers with IBM Research and the University of Oxford have published a new paper in the journal Science this week that announced the successful creation and imaging of this structure for the first time ever, revealing 18 carbon atoms linked together to form a complete ring, known as a cyclocarbon.


Yoshito Tobe, a chemist at Osaka University in Japan, said that the synthesis of the cyclocarbon for the first time was an incredible achievement for the team at IBM and Oxford.

“Many scientists, including myself, have tried to capture cyclocarbons and determine their molecular structures, but in vain," Tobe said.

Carbon is one of the most common elements in the universe, and depending on how the carbon structures itself, carbon atoms can produce different carbon molecules, called allotropes. These different forms of carbon can have different properties just like any other chemical compound, which is how clear diamonds with a high level of hardness and the kind of dark, opaque, and chalky lumps of charcoal used by artists for sketch work can both be made of pure carbon.

The difference is in how many other carbon atoms a given carbon atom bonds with in the material. In a diamond, each carbon atom bonds with four other carbon atoms around it, whereas in graphite and graphene, each carbon atom bonds with three of its neighbors. Other bonds are possible, however, and chemists debated the structure of cyclocarbons, theoretical structures that would bond with only two other carbon atoms which could be arranged to create a closed loop or ring.

To synthesize the cyclocarbon, the research team began with a triangular-shaped molecule made out of carbon and oxygen and used electrical currents to manipulate its structure, removing the oxygen and excess carbon to eventually produce the long-sought ring, known as carbon-18.

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A team of Oxford chemists prepared the specific carbon and oxygen structure that the IBM Research team in Zurich, Switzerland modified with electric currents, pealing away atoms the way a sculptor carves away the excess stone to reveal a sculpture underneath. After many attempts, the IBM Researchers cut away the last of the excess oxygen and carbon atoms revealing the final ring of 18 carbon atoms. "I never thought I would see this," said Lorel Scriven, a chemist and member of the Oxford team.

Initial tests have been done to finally describe the properties of carbon-18, one of the great mysteries about the structure. In an encouraging result, carbon-18 appears to be semiconductive, opening up the possibility of using straighten chains of carbon-18 to create molecular-scale electronic components.

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