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.