One-step construction of a thiolysis-driven chemodosimeter for robust colorimetric and turn-on fluorometric hydrogen sulfide detection integrated with a smartphone platform for environmental monitoring.

Herein, a novel dinitrophenyl-appended phthalonitrile chemodosimeter DNPPn, readily synthesized in a single step, was introduced as a colorimetric and fluorescent probe for the selective and sensitive detection of hydrogen sulfide (H2S), and validated in real sample matrices. The molecular structure of the DNPPn was comprehensively elucidated using single-crystal X - ray diffraction analysis (XRD), and well-established spectroscopic techniques (1H NMR, 13C NMR, ESI-MS, and FT-IR). DNPPn exhibited a broad concentration range, and dual-mode (colorimetric and turn-on fluorometric) sensing capabilities for the on-site detection of H2S via a dinitrophenyl ester thiolysis mechanism, definitively verified through HR-MS Density Functional Theory (DFT) analysis. DNPPn demonstrated remarkably low limits of detection (LOD) values (88.5 ppb for UV-Vis and 65.9 ppb for fluorescence) with ultra-fast response time (30 s), well below than the permissible exposure limits defined by Occupational Safety and Health Administration (OSHA) and National Institute for Occupational Safety and Health (NIOSH) (20.0 ppm and 10.0 ppm, respectively). The thiolysis reaction triggers a pronounced color shift from pale-yellow to orange by regulating the intramolecular charge transfer (ICT) mechanism. This allows on-site monitoring through a smartphone-assisted platform. Furthermore, the practical feasibility of DNPPn was proven via its evaluation in real water and food samples. Overall, these findings demonstrate that DNPPn is a highly selective, sensitive and versatile tool for the instantaneous and on-site H2S detection, with promising applications in environmental monitoring and the public health protection. ENVIRONMENTAL IMPLICATION: Although H2S attends to critical physiological operations, its widespread presence in water resources poses a significant risk to ecosystems and human health. H2S concentration in biological tissues varies widely, the safety margin between physiological and toxic levels of H2S is quite narrow, and its rapid catabolism causes continuous fluctuations in concentration, complicating precise quantification. Therefore, there is a great need for multichannel chemosensors that can easily and continuously monitor H2S in real samples. This study presents a novel fluorescent/colorimetric probe (DNPPn) for the highly selective and sensitive quantification of H2S in real samples with outstanding sensing performance.