Scientists Finally Capture Carbon’s Most Elusive Shape

• Chemists have successfully created a brand-new form of carbon.
• The molecule, known as cyclo[48]carbon, contains 48 carbon atoms arranged in a striking ring pattern of alternating single and triple bonds.
• Remarkably, it is stable enough to be studied in liquid at room temperature, a first for this type of structure.
• This achievement marks only the second time scientists have produced a new carbon allotrope that can be examined under normal lab conditions.
• The discovery was reported on August 14 in Science.

Breakthrough in Carbon Chemistry

Researchers at Oxford University’s Department of Chemistry have successfully created a cyclocarbon stable enough to be examined in solution at room temperature using advanced spectroscopic methods.

Developing a new molecular form of carbon that can withstand normal laboratory conditions is extremely rare. The only previous success came in 1990, when Krätschmer et al. synthesized fullerenes (Nature 1990).

In this latest breakthrough, scientists produced cyclo[48]carbon as a [4]catenane, meaning the C48 carbon ring was threaded through three larger molecular loops. These protective loops, or macrocycles, shield the ring and prevent it from breaking apart, greatly improving its stability.

First Room-Temperature Cyclocarbon in Solution

Until now, pure carbon rings could only be observed in the gas phase or at cryogenic temperatures (4 to 10 K). The Oxford team has now created a version that remains stable in liquid solution at 20°C, with a half-life of 92 hours. This stability was achieved by combining several strategies: using threaded macrocycles, selecting a large carbon ring with minimal strain, and designing gentle reaction conditions for the unmasking step (where the precursor molecule is converted into the final structure).

To confirm the result, the team analyzed the cyclocarbon catenane using mass spectrometry, NMR, UV-visible spectroscopy, and Raman spectroscopy. A single strong ¹³C NMR signal was detected for all 48 sp¹ carbon atoms, showing that each atom occupies the same chemical environment. This finding provides compelling evidence for the correct cyclocarbon catenane structure.

A Fundamental Step for Future Research

Lead author Dr. Yueze Gao (Department of Chemistry, University of Oxford) said: “Achieving stable cyclocarbons in a vial at ambient conditions is a fundamental step. This will make it easier to study their reactivity and properties under normal laboratory conditions.”

Study senior author Professor Harry Andersen (Department of Chemistry, University of Oxford) said: “This achievement marks the culmination of a long endeavour to synthesise cyclocarbon catenanes, based on the hope that they might be stable enough to study at room temperature. The original grant proposal was written in 2016, based on preliminary results from 2012–2015. It is satisfying to have reached this point, because there were many times when the goal seemed unrealistic and unachievable. This work would not have been possible without the outstanding facilities for NMR spectroscopy in the Department of Chemistry at Oxford.”

Reference: “Solution-phase stabilization of a cyclocarbon by catenane formation” by Yueze Gao, Prakhar Gupta, Igor Rončević, Coral Mycroft, Paul J. Gates, Anthony W. Parker and Harry L. Anderson, 14 August 2025, Science.
DOI: 10.1126/science.ady6054

The study also involved researchers from the University of Manchester, the University of Bristol and the Central Laser Facility, Rutherford Appleton Laboratory.

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