SuFEx-Enabled Catalytic Synthesis of Fluorescent Organosulfur Polymers for the Rapid Detection of Explosives.

The rapid and straightforward detection of explosive molecules is crucial for ensuring public safety and national security. Herein, a new series of conjugated polymers, referred to as the SP series, incorporating pentiptycene structures with organosulfur (sulfide and sulfonate ester) side chains, which is developed via sulfur(VI)-fluoride exchange (SuFEx) click chemistry. These polymers enhance the detection capabilities of nitroaromatic explosives through improved fluorescence quenching mechanisms. The method involved synthesizing β-sulfido sulfonyl fluorides via superbase-catalyzed thia-Michael reactions, introducing sulfonates through SuFEx conjugation, and assembling the polymers via palladium-catalyzed Sonogashira coupling. The SP-7 polymer, in particular, shows exceptional performance in explosives detection (DNT and TNT), achieving a >99% quenching efficiency within a few seconds, far surpassing existing polymer sensors. The fluorescence quenching dynamics via electron transfer in the SP-7 polymer are thoroughly elucidated using time-resolved photoluminescence and transient absorption spectroscopy, revealing that both static and dynamic quenching processes are highly effective. Remarkably, a straightforward yet powerful TLC-spotting-based technique is demonstrated that enables the rapid (<30 s) and selective detection of explosives under UV irradiation. This finding underscores the potential of SP series polymers in explosive practical detection, promising significant improvements in public security technologies.