Fluoride detection by a pyrene functionalized imidazole-based fluorescent sensor: Bioimaging and anti-counterfeiting applications

A novel chromogenic and fluorogenic probe 2-(4-(1-(benzo[d]thiazol-2-yl)-4,5-diphenyl-1H-imidazol-2-yl)benzylidene)-N-(pyren-1-ylmethylene)hydrazine-1-carbothioamide (BIPC), was synthesized by combining classical imidazole and pyrene fluorophores in the thiosemicarbazone system to access versatile sensing qualities. The design of BIPC was integrated with imidazole and pyrene fluorophores into a thiosemicarbazone framework, enabling both colorimetric and fluorometric sensing capabilities, which improved the probe's versatility for Fdetection. The chemical structure of BIPC was successfully characterized by 1 H, 13 C NMR, and HRMS analyses. BIPC features aggregation-induced emission properties and forms nano aggregates, which were characterized by dynamic light scattering (DLS) methods. The addition of Fproduces a significant bathochromic absorbance and a ratiometric emission with the facilitation of photoinduced electron transfer (PET) followed by intramolecular charge transfer (ICT) processes. The colorimetric and fluorometric efficacy of BIPC was evaluated by its limit of detection and quantification, which were calculated to be 82.3 and 3.46 nM respectively. In the present study Jobs plot, DFT, HRMS, and 1 H NMR experiments were used to validate BIPC's detection mechanism and binding stoichiometry of F. An excellent reversibility and regeneration of BIPC was achieved with the sequential introduction of trifluoroacetic acid (TFA). The practicability of this sensing system was primarily authenticated by an environmental water sample analysis. Significantly, BIPC is a promising contender for luminescent organic materials used in anti-counterfeiting applications. In addition, fluorescence bio-imaging experiments demonstrate the potential capability of BIPC to detect Fin E-Coli cells.