Sub‐Nanoconfined Aggregation‐Induced Emission Molecules via Stacked Layers of Microtubular Covalent Organic Frameworks for Enhanced Fluorescence

Abstract Functionalizing aggregation‐induced emission molecules (AIEs) by confining them in porous materials is attracted extensive attention. Here stacked layers of hollow microtubular covalent organic frameworks (HT‐COFs) are introduced as sub‐nanoconfined sites (0.37 nm) to confine AIEs. The spacious hollow channels allow unimpeded entry for AIEs, while the interlayers perpendicular to the channels partially incarcerate the AIEs within the COFs layers. This effectively restricts the intramolecular rotation of AIEs and facilitates its radiative processes. Through exchanging of various AIEs, the versatility of the COFs interlayer as a restriction site is demonstrated. Furthermore, the sub‐nanoconfined fluorescence in AIEs@HT‐COFs displays reversible temperature dependence. Based on this, a temperature‐tunable fluorescent Micro‐QR code device is fabricated, wherein the encoded information disappears at a high‐temperature and reemerges at a low‐temperature. This work offers novel insights into confined fluorescence within functional materials and the fabrication of AIEs‐COF multiplex frameworks.