A dual-emission ratiometric fluorescent probe based on carbon quantum dots and a lanthanide MOF for the selective detection of TNT and Fe(3+) in aqueous phase.

Water contamination by explosive compounds and heavy metal ions poses serious risks to ecosystems and human health worldwide. Among them, 2,4,6-trinitrotoluene (TNT), a persistent nitroaromatic explosive, is frequently found in military and industrial wastewater, as well as residues from civilian blasting activities. Ferric ions (Fe), commonly discharged through various industrial processes, also present a significant environmental threat. Therefore, the development of effective detection methods for both TNT and Fe in aquatic environments is of great importance for environmental monitoring and pollution control. Herein, we report a novel dual-emission ratiometric fluorescent probe, CNQDs/Eu-MOF-76, capable of simultaneously and selectively detecting both TNT and Fe in aqueous environments. The probe combines blue-green fluorescence from carbon quantum dots (CNQDs, 496 nm) and red fluorescence from Eu-MOF-76 (618 nm), enabling a distinct ratiometric response upon analyte recognition. It exhibits high sensitivity, with a detection limit for TNT as low as 0.4 nM and a linear range from 0 to 6.3 nM. Moreover, the probe shows excellent selectivity toward TNT and Fe over various common ions. Its practical applicability was validated in real water samples (river, tap, and drinking water), demonstrating satisfactory recoveries and good reproducibility. This strategy offers a rapid, cost-effective, and reliable tool for environmental monitoring and water quality protection.