Specific and Oriented Encapsulation of Fullerene C70 into a Supramolecular Double-Decker Cage Composed of Shape-Persistent Macrocycles.

An efficient strategy for the specific recognition of ellipsoidal fullerenes uses molecular containers with well-designed three-dimensional (3D) nanospaces. We describe the synthesis of a supramolecular double-decker cage composed of shape-persistent metallomacrocycles and pillar ligands. A discrete 3D nanospace was built within the molecular framework of the shape-persistent-macrocycle/bidentate-pillar molecule. The single-crystal structure of the supramolecular cage reveals a uniquely shaped inner cavity with a size and net volume (>670 Å3 ) that are well matched to the shape and size of C70 . The cage exhibited higher selectivity for C70 over C60 , the smaller carbon allotrope. We suggest that such C70 -selective recognition is derived from multiple CH-π interactions between hydrogen atoms inside the cage and C70 .