Design, Synthesis, and Application of a Novel Schiff Base‐1,2,3‐triazole Fluorescent Probe for Selective Detection of Aluminum Ions

A novel fluorescent "turn-on" probe, N'-((2-hydroxynaphthalen-1-yl) methylene)-5-methyl-2-phenyl-2H-1,2,3-triazole-4-carbohydrazide (G₃), was designed and synthesized. The structure was fully characterized by ¹H NMR, ¹³C NMR, and MS. G₃ exhibits highly selective and sensitive fluorescence enhancement toward aluminum ions in aqueous solution. Job's plot analysis, ¹H NMR titration, and mass spectrometric studies confirm a 1:1 binding stoichiometry between G₃ and Al³⁺, which is further supported by density functional theory (DFT) and quantum chemical calculations elucidating the sensing mechanism. Notably, the probe achieves an exceptionally low detection limit of 1.162 nM, outperforming most previously reported Al³⁺ sensors. Practical applicability was demonstrated through Al³⁺ detection in environmental water samples and the development of a portable swab test kit. Cytotoxicity assays reveal low cellular toxicity, while fluorescence imaging in HeLa cells and zebrafish confirms its biocompatibility and bioimaging capability. These results highlight G₃ as a promising probe with high sensitivity, excellent selectivity, and significant potential for applications in environmental monitoring and biological sensing.