Malachite green (MG), a cost-effective triphenylmethane dye known for its insecticidal and germicidal properties in aquaculture, unfortunately poses significant environmental and human health-related risks due to its mutagenic, carcinogenic, and teratogenic effects. Herein, a novel diamine-functionalized zirconium-based metal organic cage (Zr-MOC), abbreviated as ZrT-1-(NH2)2, was synthesized through microwave-assisted method, serving as a ratiometric fluorescent sensor for the precise detection of MG in aquaculture water. When the pH value was adjusted to 3.0, the probe solution exhibited two distinct characteristic emission bands centered at 454 nm and 582 nm, upon excitation at 365 nm. With the addition of MG, the emission intensity at 582 nm was significantly quenched, whereas the fluorescence intensity at 454 nm was gradually increased. The related experimental data and DFT calculations revealed that the quenching process is predominantly governed by the inner filter effect and static quenching mechanisms. Notably, the ratiometric fluorescence probe exhibited a good linear correlation with the MG concentration within the range of 1.37–17.81 nM, boasting a remarkably low detection limit of 1.05 nM. Furthermore, the proposed ZrT-1-(NH2)2 ratiometric fluorescence probe features high recoveries (95.37–104.93 %) and low relative standard deviations (RSD<3.5 %) for the detection of trace MG in aquaculture water, indicating its feasibility and practicality for MG detection.
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