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Macrocycle-to-macrocycle conversion is an effective strategy to construct new macrocyclic arenes with specific structures. Herein, a new class of chiral macrocyclic arene, namely, octopus[5]arenes (Oc5s), cannot be synthesized by the direct approach from the corresponding chiral monomers but can be successfully achieved by a macrocycle-to-macrocycle conversion strategy utilizing racemic pagoda[5]arenes as the starting materials. It was found that enantiomeric Oc5s showed fixed conformations and stable chiral structures and exhibited significant chiral recognition toward chiral diamines.

Herein, host-guest complexation between pagoda[ n ]arenes ( n = 4, P4 ; n = 5, P5 ) and tropylium cation ( G ) was investigated in detail. It was found that both P4 and P5 showed surprisingly strong binding affinities toward the tropylium cation with association constants of more than 10 7 M -1 for the 1:1 host-guest complexes. The theoretical calculations showed different host-guest complexion ways for complexes G @ P4 and G @ P5 and the strong π···π interactions and multiple C-H···π interactions play a very important role in the formation of these stable complexes, respectively. Moreover, the switchable processes of guest binding and release in the complexes can be effectively controlled by redox stimuli, and they can be also visible by the color and fluorescence changes.