Bowl on the ring: Molecular crowns hosting fullerenes synergistically by buckybowl and nanohoop

Abstract

Curved π‐electron systems show unique properties and assembly feature that enable the specific applications in materials science and supramolecular chemistry. Herein, fullerene, carbon nanohoop and π‐bowl are integrated by the coupling of covalent and supramolecular tactics. Firstly, π‐bowl trichalcogenasumanenes (TCSs) are fused with a carbon nanohoop [10]CPP via covalent joint to form molecular crowns 4a/4b, which show structural and electronic complementarity and accordingly strong binding affinity to C60/C70. Secondly, the supramolecular assemblies of 4a/4b with fullerenes afford the host‐guest complexes 4a/4b⊃C60/C70 in solution (molar ratio, 2:1) and solid state (molar ratio, 1:1). In the crystals of host–guest complexes, the intra‐cluster and inter‐cluster interactions are respectively dominated by the [10]CPP and TCSs moieties of 4a/4b. Additionally, it is found that 4a/4b are good photosensitizers for generating 1O2 and show structural adaptability in accordance to assembly conditions. 4a/4b take an endo‐conformation in their own crystals with TCSs and [10]CPP moieties being bowl‐shaped and elliptical, respectively. In contrast, the [10]CPP on 4a/4b changes into circular and the TCSs moiety becomes flat (for 4b) or shows bowl inversion to be exo‐conformation (for 4a) in 4a/4b⊃C60/C70.