A Benzimidazole Linked Covalent Triazine Framework as a Fluorescent Probe for Selective Multiplatform Detection of Trinitrophenol.

The persistence and rising levels of environmental pollutants have driven the development of functional materials for their sensitive detection. Trinitrophenol (TNP), a highly toxic and explosive compound, requires urgent monitoring. In this work, a novel benzimidazole-based covalent triazine framework, CTF , was synthesized via solvothermal condensation of 1,2,4,5-benzenetetraamine tetrahydrochloride and 2,4,6-tris(4-formylphenoxy)-1,3,5-triazine. The resulting CTF exhibited excellent selectivity towards TNP, with a low detection limit of 1.38 nM and a linear detection range from 32.15 × 10 to 4.6 × 10 M. Fluorescence quenching was attributed to a combination of inner filter effect (IFE), Förster resonance energy transfer (FRET), and photoinduced electron transfer (PET) mechanisms. To enhance practical usability, a fluorescent film was developed by incorporating the CTF into a polyvinyl alcohol (PVA) matrix. The resulting CTF-PVA film showed high flexibility, water stability, and a fast fluorescence quenching response upon TNP exposure. Furthermore, a portable device was designed for rapid and user-friendly detection of TNP based on fluorescence quenching. This dual strategy solution-phase sensing and film-based detection with a portable device offers an efficient and practical approach for detecting nitroaromatic explosives in real-world settings.