Recent advances in chromophore-based near-IR (NIR) chemosensors for the selective detection of phosgene and nerve...

Chromophore-based near-IR (NIR) chemosensors have emerged as highly effective tools for the detection of toxic nerve agents and phosgene due to their low background interference, deep penetration, and high sensitivity. This minireview summarizes recent advances in NIR probes achieving detection limits from the micromolar level down to ppb and nanomolar ranges. Key sensing mechanisms, including PET and ICT processes, acylation- and carbonylation-induced cyclization, spirolactam ring opening, oxime- and amide-to-cyanide conversion, DCP-mediated reactions with pyridine and pyrrole nitrogen atoms, DCP-activated intramolecular amidation, non-covalent Lewis acid-base interactions, intramolecular cyclization, and MLCT pathways, are critically discussed. The review further highlights practical applications of these chemosensors in phosgene detection in solution, gas, vapor, and soil extracts, as well as in vivo and cellular imaging, exemplified by studies in Arabidopsis thaliana. Emphasis is also placed on portable and low-cost platforms, including filter-paper- and test-strip-based sensors, enabling rapid vapor detection, soil analysis, security ink applications, and on-site monitoring. This review will be highly beneficial for readers by providing clear design principles, mechanistic insights, and recent progress that can guide the rational development of next-generation NIR sensors for the sensitive and selective detection of phosgene and nerve agents. Overall, this article provides a concise perspective on recent progress and future directions toward real-world deployment of NIR chemosensors for hazardous chemical surveillance.