Structures and Supramolecular Properties of Inclusion Complexes of Anthracene‐Triptycene Nanocages with Fullerene Guests and Their Dynamic Motion as Molecular Gyroscopes

Abstract

Three derivatives of macrocyclic cage compounds consisting of diarylanthracene and triptycene units were synthesized. These nanocages formed host‐guest complexes with C60 and other fullerene guests as confirmed by 1H NMR and fluorescence spectroscopy. The association constant of the mesityl and 2,4,6‐tributoxyphenyl derivatives with C60 was determined to be 2.2 × 104 L mol−1, which was larger than that of the pentafluorophenyl derivative. Direct experimental evidence of the complexation was obtained by X‐ray diffraction analysis: the guest C60 molecule was included in the cavity via multipoint CH⋅⋅⋅π interactions. Dynamic disorders of the included C60 molecule in variable‐temperature X‐ray analysis indicated uniaxial motion, such as gyroscopic motion. The unique dynamic behavior of the spherical C60 rotor anchored by the cage stator via CH⋅⋅⋅π interactions in the crystal, as well as substituent effects on the association properties, are discussed with the aid of DFT calculations.

Unraveling the Nature and Strength of Non‐Covalent Interactions on the Surface of Fullerenes

“…Toyota et al expanded the molecular design to include the synthesis of bicyclic cage-like macrocycles composed of anthracene components. [44,45] Notably, they synthesized a series of anthracene-based nanocages that featured various electron donating or accepting substituents (13 a, 13 b, 13 c) and compared the K SV values of these compounds with those of C 60 or C 70 through fluorescence titration experiments (see Figure 5). The results revealed that the K SV values decreased in the following order: 13 a (( 22 (110 � 10) × 10 3 L mol À 1 for C 70 ), suggesting that the binding abilities decreased as electron-withdrawing groups were introduced.…”

Confinement effects on the structure and reactivity of encapsulated buckybowls in cycloparaphenylene

“…1, a CH-p complex is predicted to be formed while the buckybowl is encapsulated as a lying orientation in which the C-H bonds of the buckybowl at the edge interact with the interior surface of CPP. It should be a Key Laboratory for Macromolecular Science of Shaanxi Province, School of noted that some host-guest complexes assembled by CH-p interactions have been successfully synthesized in very recent experiments, [16][17][18][19][20] despite CH-p interaction generally being considered a relatively weak non-covalent interaction. On the other hand, since both sumanene and corannulene can be treated as the fragments of fullerenes, the guest buckybowl is also expected to be stabilized in a standing orientation and the host-guest moieties should be assembled by the p-p interaction between the inner wall of CPP and the convex surface of buckybowls.…”