Modular Construction of Vinylene‐Linked Covalent Organic Frameworks with Tunable Emission for Tumor Visualization

Abstract

AbstractCovalent organic frameworks (COFs) with ordered π structures are very promising in porous light‐emitting materials. However, most of these COFs are either poor in luminescence or lack of water‐stability. Herein, a series of isostructural D−A vinylene‐linked COFs were constructed based a new D2h symmetric linker 1,4‐bis(4,6‐dimethyl‐1,3,5‐triazin‐2‐yl)benzene (TMTA) with high crystallinity, comparative high surface area and excellent chemical/thermal stability. Impressively, their adsorption and luminescence wavelength vary with respect to the density of π‐systems in the electron‐donating group, which constitute the foundation for molecular engineering the luminescent properties of vinylene‐linked COFs. The DFT calculations further established the relationship between the luminescence properties and the donor electronic structure. Moreover, one of representative COF named FZU‐203 showed inspiring applications in bioimaging, which may further provide strategic guidance for the use of vinylene‐linked COFs as fluorescent nanoprobes in non‐invasive medical diagnosis and visualization therapy of tumors.