A naphthimide based fluorescent probe for the detection of thiophenols and its application in actual water and food

Thiophenol (PhSH) and its derivatives are widely employed as common industrial raw materials, while they also pose high toxicity for animals and aquatic organisms. Herein, a novel fluorescent probe P1 was constructed, based on photo-induced electron transfer (PET) mechanism, using naphthimide as the fluorophore and 7-nitrobenzoxadiazole as the recognizing group. Probe P1 exhibited an “Off-On” fluorescence recognition response to PhSH by nucleophilic substitution reaction. The probe displayed advantageous properties for the recognition of PhSH, including a chromogenic response, high selectivity, fast response (< 90 s), and a large Stokes shift (150 nm). In addition, probe P1 exhibited a good linear response to PhSH within the range of 0–9 μM, and the limit of detection (LOD) is 21 nM. Furthermore, probe P1 has been successfully applied for the efficient and rapid PhSH detection in environmental water and actual food samples.