Oxford chemists have synthesized cyclo[48]carbon—a 48-atom carbon ring with alternating bonds that remains stable in solution at room temperature, enabling its characterization and opening new frontiers in carbon chemistry.
The atoms are connected by alternating single and triple bonds· The ring is surprisingly stable in liquid at room temperature. Other cyclocarbons needed very low temperatures or gas phase· This one lasts with a half-life of 92 hours at 20 °C.
Stability comes from threading the ring through three large molecular loops, forming a [4] catenane. These loops shield the carbon ring from reacting away. Researchers used mass spectrometry, NMR, UV–vis, and Raman spectroscopy to confirm structure. A single strong ^13C NMR signal showed all 48 sp¹ carbons are equivalent. It is only the second new carbon allotrope that is stable under ordinary lab conditions; the first was fullerenes in 1990. Dr. Yueze Gao noted this is a key step for studying cyclocarbons in normal labs. Prof. Harry Anderson said the success caps a decade-long effort