Since their initial discovery, fullerenes have been a source of major interest due to their unique structure, reactive properties, and crystallographic challenges. The high rotational symmetry of empty cage leads to disorder in crystal structures, further leading to difficulty in locating atoms and uncertain bond lengths. This is especially troublesome when a higher fullerene has multiple possible cage isomers. A clever solution to the problem can be found using a technique known as cocrystallization – where harnessing the non-covalent interaction between the fullerene and a second molecule (the cocrystallization agent) to reduce the disorder of the fullerene. A unique cocrystal was discovered with an asymmetric unit cell of 12 C70 fullerene molecules, 12 NiII(OEP) molecules, and 18 para-xylene molecules, and its subsequent phase transition as the crystal is warmed from 90 K to 190 K. This cocrystal was also compared to other C70 fullerene and MII(OEP) cocrystals to systematically determine the effects of the cocrystallization agent and solvent arrangement within the crystal. Further studies on other C70 cocrystals showed how changing the solvent to a chlorinated solvent could additionally produce larger cocrystals, such as a 3CoII(OEP) molecules and 2C70 molecules in the cocrystal, where one of the MII(OEP) molecules is ruffled to embrace both fullerenes at once.

Fullerene nanostructures: Exploring fullerene cocrystals

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.