Theoretical study on the sensing mechanism of fluorescent probes based on benzimidazole for TNT and TNP detection

Trinitrophenol (TNP) and trinitrotoluene (TNT) stand as the most prevalent nitro-based explosives in our daily lives. Due to the considerable destructive power and significant impact on the environment, the detection of these materials is of great importance. In this study, the sensing mechanism of a novel fluorescent probe towards TNT and TNP was intensively investigated. Initially, the molecular configurations of the probe and the binding products were examined. Subsequently, the recognition interaction and the combination site of the fluorescent probe were determined through energy analysis. By comparing the electronic spectroscopy data and the energy profile, we confirmed that the probe sensing TNP is actually via recognizing its ion. According to the frontier molecular orbital analysis, we attributed the fluorescence quenching of detection products to be the photo-induced electron transfer mechanism.