Overview

• The team synthesized the cyclo[48]carbon as a [4]catenane by linking three macrocyclic rings onto cobalt-protected polyyne precursors and then removing the metal groups to unmask the carbon ring.
• Mass spectrometry, UV–visible and Raman spectroscopy, along with a single intense 13C NMR resonance for all 48 sp1 carbons, provided convergent evidence for the symmetrical catenane structure in solution.
• In deuterated dichloromethane at 20 °C and concentrations up to 300 µM, the protected catenane exhibits a half-life of about 92 hours, enabling extended spectroscopic analysis under ambient lab conditions.
• Researchers also detected an unprotected cyclo[48]carbon species at low concentration, estimating a half-life of approximately one hour and noting its UV–visible spectrum matches that of the protected form.
• Published in Science, this represents only the second new molecular carbon allotrope accessible under normal laboratory conditions since fullerenes and paves the way for crystallization, X-ray diffraction and studies of its reactivity and electronic properties.