“One-Stone, Three-Birds”: Discrimination of Triple Chemical Threats in Both Solution and Vapor Phases on a Single AIEgen Platform by Exploiting an Electrophilicity Gradient

The discriminative detection of multiple chemical threats remains a formidable challenge for conventional molecular probes. Herein, we report a versatile sensing platform that achieves unambiguous identification of nerve agents, phosgene, and oxalyl chloride in both solution and vapor phases by capitalizing on their inherent electrophilicity gradient. The system integrates an AIE-active hydroxamic acid probe (TPE-HOA) with 1,8-diazabicyclo5.4.0undec-7-ene (DBU), where DBU acts not merely as a base but as a key discriminatory component. This synergistic combination enables a kinetic competition strategy that directs each analyte toward a distinct optical pathway. In solution, oxalyl chloride triggers a rapid colorimetric change, while phosgene and nerve agents are differentiated via precipitate formation and fluorogenic kinetics. On test strips, vapor discrimination is accomplished by monitoring time-dependent fluorescence profiles and employing phosgene as a diagnostic reagent. Critically, the platform's efficacy is demonstrated with authentic nerve agents (VX, sarin), phosgene, and oxalyl chloride, underscoring its practical utility. This work establishes a new "reactivity-based discrimination" paradigm for the development of advanced multi-analyte sensing systems.