  Stimulated by the recent observation of {\pi}-{\pi} interactions between C60
and corannulene subunits in a molecular tweezer arrangement (J. Am. Chem. Soc.
2007, 129, 3842), a density functional theory study was performed to analyze
the electronic structure and properties of various noncovalent corannulene
complexes. The theoretical approach is first applied to corannulene complexes
with a series of benchmark molecules (CH4, NH3, and H2O) using several
new-generation density functionals. The performance of nine density
functionals, illustrated by computing binding energies of the corannulene
complexes, demonstrates that Zhao and Truhlar's MPWB1K and M05-2X functionals
provide energies similar to that obtained at the SCS-MP2 level. In contrast,
most of the other popular density functionals fail to describe this noncovalent
interaction or yield purely repulsive interactions. Further investigations with
the M05-2X functional show that the binding energy of C60 with corannulene
subunits in the relaxed molecular receptor clip geometry is -20.67 kcal/mol.
The results of this calculation further support the experimental interpretation
of pure {\pi}-{\pi} interactions between a convex fullerene and the concave
surfaces of two corannulene subunits.
