Structural diversity of host-guest and intercalation complexes of fullerene C ₆₀

Pristine fullerene C ₆₀ has a fcc structure. Crystallisation of the fullerene in a variety of solvents can lead to inclusion complexes, as well as discrete host-guest complexes in the presence of cavitands and porphyrins, and related molecules. The complexes retain varying degrees of fullerene⋯fullerene interactions at the van der Waals limit, except in a limited number of cases where the fullerenes are completely shrouded by one or more included/host molecule. Analysis of the fullerene⋯fullerene interactions in these complexes reveals a diverse structural arrangement of the fullerenes. They can be organised into dimers, single linear columns or zigzag chains, double columns, spectacular fivefold Z-shaped columnar arrays, hexagonal close-packed layers, corrugated sheets, honeycomb motifs, non-close-packed layers and complex three-dimensional networks. Disorder of the fullerenes in the solid state is common, although structures with close-packed planar arrangements of C ₆₀ molecules and/or with symmetry matching between the host molecule and the fullerene (two-, three- and fivefold symmetry) tend to have less disorder of the fullerene.