At a Glance
- Chemists have synthesized a cyclo[48]carbon ring that remains stable enough for detailed spectroscopic characterization in a solution at room temperature, a breakthrough for materials science.
- The team protected the highly reactive 48-atom carbon ring by threading it through three larger macrocycles, creating a mechanically interlocked structure known as a [4]catenane.
- Previously, these pure carbon rings, or cyclocarbons, were too unstable to be studied except in the gas phase or at cryogenic temperatures near absolute zero.
- Spectroscopic analysis, including a single resonance in its 13C NMR spectrum, confirmed that all 48 carbon atoms were chemically equivalent, providing strong evidence for the ring’s structure.
- This landmark research, which represents a rare new class of molecular carbon allotrope, was led by scientists at the University of Oxford and published in the journal Science.
Scientists at the University of Oxford’s Department of Chemistry have achieved a long-sought goal in materials science: creating a ring of pure carbon that is stable enough to be studied in a solution at room temperature. This new molecular carbon allotrope, a form of carbon with a distinct structure, joins the exclusive club of carbon forms, including diamond, graphite, and fullerenes. The research, a rare milestone not seen since the synthesis of fullerenes in 1990, was published in the journal Science.
The breakthrough involves a molecule named cyclo[48]carbon, a delicate ring consisting of 48 carbon atoms. On its own, the structure is highly reactive and would quickly fall apart under normal conditions. To solve this, the research team constructed a protective scaffold around it, creating a structure known as a catenane. This was achieved by threading the C48 ring through three larger, stable molecules, or macrocycles, which act as a kind of molecular armor, preventing other chemicals from reaching and destroying the fragile carbon backbone.
This innovative stabilization technique enabled the team to produce macroscopic quantities of the molecule and study it in a vial at 20 °C. Previous attempts to study cyclocarbons were limited to the gas phase or cryogenic temperatures between 4 and 10 kelvins, just a few degrees above absolute zero. The new molecule has a half-life of 92 hours, providing ample time for analysis. “Achieving stable cyclocarbons in a vial at ambient conditions is a fundamental step,” said lead author Dr. Yueze Gao of the Oxford Department of Chemistry in a university press release.
The team confirmed the structure’s perfect ring shape using a suite of advanced analytical tools, including mass spectrometry and nuclear magnetic resonance, or NMR, spectroscopy. The NMR results were particularly definitive, showing a single signal for all 48 carbon atoms. This indicated that every atom in the ring was in an identical chemical environment, which is powerful evidence of a symmetrical, circular structure. “This achievement marks the culmination of a long endeavor,” said study senior author Professor Harry Andersen. “It is satisfying to have reached this point, because there were many times when the goal seemed unrealistic.”
References
- Gao, Y., Gupta, P., Rončević, I., Mycroft, C., Gates, P. J., Parker, A. W., & Anderson, H. L. (2025). Solution-phase stabilization of a cyclocarbon by catenane formation. Science, 389(6761), 708–710. https://doi.org/10.1126/science.ady6054
- University of Oxford. (2025, August 14). Chemists synthesize a new allotrope of carbon. Phys.Org; University of Oxford. https://phys.org/news/2025-08-chemists-allotrope-carbon.html
