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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 107 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.

Regulating of pore environment is an efficient way to improve the performance of covalent organic frameworks (COFs) for specific application requirements. Herein, the design and synthesis of two pyrene‐based 2D COFs with ‐H or ‐Me substituents, TFFPy‐PPD‐COF and TFFPy‐TMPD‐COF are reported. Both of them show long order structure and high porosity, in which TFFPy‐PPD‐COF displays a larger pore volume and bigger BET surface area (2587 m2 g−1, 1.17 cm3 g−1). Interestingly, TFPPy‐TMPD‐COF exhibits a much higher vapor iodine capacity (4.8 g g−1) than TFPPy‐PPD‐COF (2.9 g g−1), in contrast to their pore volume size. By using multiple techniques, the better performance of TFPPy‐TMPD‐COF in iodine capture is ascribed to the altered pore environment by introducing methyl groups, which contributes to the formation of polyiodide anions and enhances the interactions between the frameworks and iodine. These results will be helpful for understanding the effect of pore environment in COFs for iodine uptake and constructing novel structure with high iodine capture performance.

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