Preparation of pyrene-functionalized fluorescent film with a benzene ring in spacer and sensitive detection to picric acid in aqueous phase

A fluorescent sensing film was fabricated by chemical assembling pyrene moieties on a glass plate surface via a spacer containing a benzene ring. The film was used for the detection of nitroaromatic compounds (NACs), particularly picric acid (PA), in aqueous phase. Introduction of benzene structure in the spacer favors π–π stacking between pyrene moieties on the end of each spacer, which encourages direct exposure of the fluorophore residues to aqueous phase, and thus the film is able to quickly monitor NACs. The advantages of this design have been demonstrated experimentally in terms of the highly sensitive response of the above-mentioned film to the presence of trace amounts of NACs in aqueous solution. The detection limit (DL) of the film to PA reaches 1.0 × 10−8 mol/L. Further experiments demonstrated that the sensing process is fully reversible and is free of interference from common chemicals like toluene, benzene, trichlormethane, ethanol, artificial seawater, NaOH, HCl, etc. Furthermore, fluorescence lifetime measurement revealed that the quenching is static in nature.