Constructing Highly Emissive Covalent Organic Frameworks for Fe 3+ Ion Detection via Wall Function.

Covalent 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 exhibited 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 suppressed the ACQ effects to improve light-emitting activity of COF. The TM-OMe-EBTHz-COF exhibited 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 formed three coordination sites, contributing to excellent performance in metal ions sensing. The TM-OMe-EBTHz-COF demonstrated high sensitivity and selectivity to Fe 3+ ion. Importantly, the low detection limit was below 150 nanomolar, ranking it among the best-performing Fe 3+ sensor systems. This article is protected by copyright. All rights reserved.