A "Turn-On" Fluorescent Probe for the Visual Detection of Total Iron in Wine

A turn-on fluorescent sensor (E)-4-((4-(5-fluoro-1H-benzo[d]imidazol-2-yl)benzylidene)amino)phenol (FBAP) for the detection of Fe^3+/2+ was synthesized. The fluorescence intensity of probe FBAP solution gradually increased with increased Fe³⁺ concentration. The low detection limit (LOD) was calculated to be 0.17 nM. The optimized structure and luminescent properties of FBAP were calculated by time-dependent density functional theory (TD-DFT) and Solvation Model Density (SMD). The rotation of the dihedral angle and ICT in the imine probe turned off the emission of the benzimidazole, which was restored upon cleaving the imine. Probe FBAP was successfully applied to determine whether Fe^3+/2+ in wine exceeded the standard by phone and the rapid detection of Fe^3+/2+ in the form of test strips was also conducted.