Hydrogen bonding plays a crucial role in structuring highly-ordered proteins and networks of biomolecules. The rational design and synthesis of artificial supramolecular systems that are assembled with the aid of hydrogen bonding are interesting research targets, as well.

[60]Fullerene consists of 60 sp²-hybridized carbon atoms, forming a closed shell. Chemical transformations can be used to create an orifice in C₆₀ at which functional groups can be introduced. Based on this strategy, Yasujiro Murata, Kyoto University, Japan, and colleagues have synthesized two open-[60]fullerenols that aggregate in a face-to-face dimeric configuration via intra- and intermolecular hydrogen bonding (example pictured).

The team reacted an open fullerene precursor with N-methylmorpholine N-oxide (NMO) to generate a tetracarbonyl intermediate via bond cleavage, which is then hydrolyzed to give one of the targeted open-[60]fullerenols in a yield of 88 %. Starting from the same precursor, a reaction with singlet oxygen gave a second open-[60]fullerenol in a yield of 10 %.

Both open-[60]fullerenols have a bis(hemiketal) moiety and aggregate via hydrogen bonds to form a dimeric configuration. The hydroxy groups adopt a rhomboidal or chair-like arrangement as confirmed by X-ray diffraction analysis. Such precisely controlled arrangements of nanocarbon materials could be useful in a variety of applications, such as electronic materials or molecular delivery systems.

• Synthesis of Hydrogen‐Bonded Open‐[60]Fullerenol Dimers,
  Yoshifumi Hashikawa, Shumpei Sadai, Yasujiro Murata,
  ChemPlusChem 2023.
  https://doi.org/10.1002/cplu.202300136