Structural diversity of host-guest and intercalation complexes of fullerene C60

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 center dot center dot center dot 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 center dot center dot center dot 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 C60 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. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)