A diarylethene-based colorimetric sensor for discriminative detection of H₂S and CN^- with fluorescent imaging in live...

Hydrogen sulfide (H₂S) and cyanide anions (CN^-) are toxic, significantly affecting environmental and human health. Although numerous chemosensors for H₂S or CN^- detection have been reported, most enable only separate detection. Differentiating between H₂S and CN^- using a single sensor remains challenging owing to their comparable nucleophilicity. A few H₂S sensors have been developed by utilizing the thiolysis reaction of DNPS ether combined with an aldehyde moiety; nonetheless, this strategy has not been employed to develop sensors for CN^- detection.

Herein, a unique diarylethene derivative functionalized with a 2,4-dinitrobenzenesulfonyl salicylaldehyde moiety is designed and synthesized. In this system, DNPS cleavage and nucleophilic addition to the aldehyde (-CHO) group collectively enable discriminative sensing. Consequently, both open- and closed-ring isomers demonstrated highly selective, sensitive dual colorimetric detection of H₂S and CN^-. Notably, the closed-ring isomer exhibited simultaneous discriminative detection, yielding distinct colorimetric responses for H₂S and CN^-, rapid response (<1 min), and micromolar-level sensitivity. Mechanistic studies revealed that H₂S detection proceeded via rapid nucleophilic addition to the ortho-aldehyde group, followed by spontaneous intramolecular thiolysis, while CN^- detection proceeded via 2,4-dinitrobenzenesulfonyl ester cleavage, followed by nucleophilic addition. CN^- also induced pronounced fluorescence enhancement, enabling successful bioimaging of CN^- in HeLa cells with excellent biocompatibility and low phytotoxicity.

A diarylethene-based dual-functional colorimetric sensor for discriminative detection of H₂S and CN^- was synthesized. Colorimetric discrimination of H₂S and CN^-, along with rapid, highly sensitive fluorometric detection of CN^-, was achieved. Visual detection of H₂S and CN^- using sensor-coated paper strips, together with bioimaging of CN^- in HeLa cells was successfully achieved. These findings offer insights into the design of novel diarylethene derivatives for a multi-ion-responsive unimolecular system.