C₆₀ fragments, such as corannulene, sumanene, and truxene, have pentagons adjacent to hexagons. While there are alternative methods to create fragment patterns, only a few molecules, apart from the aforementioned three, are readily accessible. Having an accessible fragment enables the exploration of new materials and opens up new frontiers in material science.

Tetsuo Iwasawa, Ryukoku University, Otsu, Japan, and colleagues have synthesized a previously unexplored octacyclic C₆₀ fragment called 4,11-Dihydrodiindeno[7,1,2-ghi:7′,1′,2′-pqr]chrysene, also known as metelykene (pictured). To create this fragment, the team used distorted dibenzo[g,p]chrysenes as a starting material, which contained two carbonyl groups and four tert-Bu groups. By employing Friedel-Crafts cyclization, they were able to construct the fragmentary skeleton on a gram scale. Subsequently, the researchers removed the substituents to obtain the desired fragment.

Furthermore, the team conducted crystallographic and computational analyses, revealing that the fragment shows a low energy barrier. This observation indicatsd that the fragment demonstrated flapping behavior in solution.

• Synthesis of an Octacyclic C₆₀ Fragment,
  Naruhiro Yoshida, Ryuhei Akasaka, Tomoya Imai, Yousuke Yamaoka, Toru Amaya, Tetsuo Iwasawa, Michael P Schramm,
  European Journal of Organic Chemistry 2023.
  https://doi.org/10.1002/ejoc.202300407