Lilia Baldauf

UC Davis

“Build-a-Bucky: Tuning Dispersion Forces to Build Fullerene Nanostructures”

Fullerenes have major chemical application potential. One such application is generating self-assembling structures. We do this by designing cocrystal growth to generate these nanostructures.


Since their initial discovery, fullerenes have been a source of major interest due to their unique structure, reactive properties, and crystallographic challenges. One potential application is to create self-assembling structures, and characterized by x-ray crystallography. The high rotational symmetry of empty cage leads to disorder in crystal structures, further leading to difficulty in locating atoms and uncertain bond lengths. 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•MII(OEP) cocrystals showed how changing the solvent produces larger cocrystals, such as a 3CoII(OEP)•2C70 cocrystal, where one of the MII(OEP) molecules is ruffled to embrace both fullerenes at once. This shows how slight modifications in the crystal formation can tune dispersion forces that form the cocrystals, and can be used to generate self-assembling nanostructures.

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