Perylenediimide-Enhanced Ultra-Sensitive Turn-on Fluorescence Detection in Interpenetrated MOFs for Nerve Agent Simulants

The urgent need for sensitive, selective, and rapid detection of nerve agents (NAs), a class of highly toxic organophosphorus compounds, has motivated the development of advanced fluorescent sensing materials. Herein, a series of interpenetrated luminescent metal-organic frameworks (MOFs) with 2,6-naphthalenedicarboxylic acid (NDC) and naphthalenediimide (NDI) or perylenediimide (PDI) ligands were reported, specifically targeting the detection of diethyl chlorophosphate (DCP), a nerve agent simulant. Among them, the 3D Zn-PDI-NDC framework demonstrates a pronounced fluorescence "turn-on" response to DCP with an ultra-low detection limit of 3.6 ppb and high selectivity, even in the presence of potential interferents, which is mainly attributed to ligand conformational reorganization accompanied by host-guest ground-state interactions. On the other hand, Zn-NDI-NDC and Zn-NDC MOFs with similar interpenetrated architectures display distinct fluorescence response behaviors, including fluorescence quenching or weak enhancement, reflecting differences in ligand electronics and host-guest interactions. Such comparative sensing behaviors in structurally related MOF sensors highlight the crucial role of ligand electronics and geometry. Overall, this work presents a PDI-based interpenetrated MOF platform with excellent DCP sensing performance and offers insights into MOF design strategies for organophosphorus nerve agent detection.