Red-emissive fluorescent probes based on PET mechanism for highly sensitive detection and multi-scenario imaging of thiophenol.

Thiophenol (PhSH) is a highly toxic aromatic thiol endangering ecosystems, food safety, and human health. Traditional detection methods are limited by instrument dependence and inability for real-time imaging. This study developed a red-emitting fluorescent probe, TTCP-DN, based on the PET mechanism. The probe employs 5-(4-diphenylamino)benzothiophene as the fluorophore and 2,4-dinitrophenoxy as the PhSH-specific recognition moiety, achieving mitochondrial targeting via a pyridine salt. Without PhSH, fluorescence is quenched; upon PhSH-induced reaction, fluorescence restores at 623 nm. The probe has low detection limit (37.8 nM), large Stokes shift (153 nm), good biocompatibility, and high selectivity. It was applied for mitochondrial imaging in 4 T1 cells, qualitative detection and semi-quantitative concentration trend analysis of PhSH in zebrafish, plant tissues, environmental, food and biological samples (recoveries 95-105%), and fabricated into portable paper-based test strips. This work provides a versatile PhSH detection tool and a paradigm for targeted probes of toxic aromatic pollutants.