Carbon exists in various forms known as homologues, each with distinct properties including differences in color and shape. For instance, in diamond, every carbon atom is connected to four neighboring carbons, while in graphite, each carbon atom is bound to three others. The newly created molecule, Cyclo[48]Carbon, features 48 carbon atoms arranged in alternating single and triple bond patterns, exhibiting sufficient stability for spectroscopic characterization at room temperature in solution.

Dr. Yuz Gao and his research team from Oxford University integrated cyclo.[48]Carbon molecules, creating a C48 ring that threads through three additional macrocycles.

These threaded macrocycles enhance the stability of the C48 by restricting access to the protected cyclocarbons.

Previously, molecular rings made entirely of carbon atoms have only been investigated in gas phase or at extremely low temperatures (4-10 K).

The researchers assert that Cyclo[48]Carbon maintains stability in a solution at 293 K (20 degrees Celsius).

This stability was achieved by utilizing threaded macrocycles, choosing larger cyclocarbons with low strain, and developing gentle reaction conditions for the non-masked step of the synthesis (where precursor molecules transform into the final product).

“Establishing stable cyclocarbons in vials under ambient conditions is a critical milestone,” stated Dr. Gao.

“This facilitates the examination of reactivity and characteristics under standard laboratory conditions.”

The team characterized the cyclocarbon catenene using a range of techniques including mass spectrometry, NMR, UV-visible, and Raman spectroscopy.

An intense observation of ¹³C NMR resonance for all 48 SP1 carbon atoms suggests that each carbon resides in a similar environment, strongly supporting the cyclocarbon catenene structure.

“The findings mark the pinnacle of our extensive efforts to synthesize cyclocarbon catenanes, based on the expectation that they may be stable enough for studies at room temperature,” remarked Professor Andersen.

The team’s research was published in the journal Science.

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Yuze Gao et al. 2025. Solution phase stabilization of cyclocarbons by catenene layers. Science 389 (6761): 708-710; doi: 10.1126/science.ady6054