Figure 7.

(a) Schematic representation of the synthesis of tetra(4-hydroxyphenyl)ethylene (TPE)-based oxacalixarene cage (TOC). (b) Cross-sectional image of the packing structure of the cage framework suggesting non-interconnected lattice voids in TOC, as illustrated by the blue Connolly surface (probe radius = 1.82 Å). (c) Pictorial representation of the synthesis of the cage-based porous organic polymer (pTOC) through Ni(0)-catalyzed Yamamoto coupling reaction. Inset: Respective digital photographs of TOC and pTOC under the illumination of UV light at 365 nm. (d) Gradual increase in the fluorescence intensity (λ_ex = 310 nm) of pTOC by bubbling CO₂ for 0–5 min and (e) recycling tests of pTOC in MeOH upon consecutive bubbling of CO₂ and addition of NH₃·H₂O. Panels b–e were reprinted in part with permission from ref (15). Copyright 2018 John Wiley and Sons.