An Ultrasensitive 1,2,3-Triazole Schiff-Based Fluorescence Probe for the Detection of Al³⁺ and Developing Application...

In this study, a novel fluorescent "turn-on" probe, (E)-N'-(2-(2-hydroxynaphthalen-1-yl) ethylidene)-2,5-diphenyl-2 H-1,2,3-triazole-4-carbohydrazide (G₄), was designed and synthesized, and fully characterized by various analytical techniques. Spectroscopic investigations revealed that G₄ exhibits excellent selectivity and sensitivity toward Al³⁺, with a 1:1 binding stoichiometry and a detection limit of 1.623 nM. Its advantages over existing probes include the lower detection limit and a distinct color reaction under UV light, which facilitates straightforward qualitative detection with lower cytotoxicity. The sensing mechanism was elucidated through density functional theory (DFT) and quantum chemical calculations. Then the practical utility of G₄ was demonstrated through recovery experiments in real water samples and its development into a portable test kit. Furthermore, cell experiments and zebrafish imaging confirmed its biocompatibility and applicability in biological systems with lower cytotoxicity. As a candidate drug that may be developed and utilized, the interactions of G₄ with two serum proteins (HSA and HIgG) were also investigated through spectrofluorometric and molecular docking analysis, revealing hydrogen bond or van der Waals forces as the main mode of action, suggesting potential for further biomedical applications. These results highlight G₄ as a highly sensitive, selective, and dual-functional fluorescent probe with significant potential for environmental monitoring and biological sensing.