Overview

• Researchers built the cyclo[48]carbon catenane by linking three macrocycle-threaded polyyne chains and removing cobalt caps to unleash the protected 48-carbon ring.
• Convergent spectroscopic techniques—mass spectrometry, UV–visible, Raman spectroscopy and a single intense 13C NMR resonance—confirmed that all 48 sp1 carbons occupy equivalent environments in the catenane.
• An unprotected cyclo[48]carbon variant was detected at low concentration with a one-hour half-life at 20 °C and a UV–visible spectrum matching the protected form.
• This experiment constitutes only the second molecular carbon allotrope synthesized for study under normal laboratory conditions since the discovery of fullerenes in 1990.
• Researchers plan to crystallize the catenane for X-ray diffraction and probe its chemical reactivity and electronic properties.