Constructing Highly Emissive Covalent Organic Frameworks for Fe3+ Ion Detection via Wall Function

Abstract

AbstractCovalent organic frameworks (COFs) represent a new type of crystalline porous polymers that possess pre‐designed skeletons, uniform nanopores, and ordered π structure. These attributes make them well‐suited for the design of light‐emitting materials. However, the majority of COFs exhibits poor luminescence due to aggregation‐caused quenching (ACQ), resulting from the strong interaction between adjacent layers. To break the limitation, the building units with three methoxy groups on the walls are used to construct TM‐OMe‐EBTHz‐COF, which suppresses the ACQ effects to improve light‐emitting activity of COF. The TM‐OMe‐EBTHz‐COF exhibits a notable emission of yellow‐green luminescence in the solid state, with a remarkably high absolute quantum yield of 21.1%. The methoxy groups and hydrazine linkage form three coordination sites, contributing to excellent performance in metal ions sensing. The TM‐OMe‐EBTHz‐COF demonstrates high sensitivity and selectivity to Fe3+ ion. Importantly, the low detection limit is below 150 nanomolar, ranking it among the best‐performing Fe3+ sensor systems.