A two-emitting dye-embedded fluorescent sensor based on zirconium MOF for effective detection of fluoride

Ratiometric fluorescent (RF) sensors, leveraging their inherent calibration mechanism, can greatly reduce the interference of irrelevant factors and exhibits superior detection sensitivity and more attractive visual detection effects in the process of quantitative analysis. Up to now, there are few probes that can detect fluorine by the proportional fluorescence signal. Herein, we constructed a RF probe for determination of fluorine by confining self-synthesized red emitting organic small molecules 10-(diethylamino)-3-hydroxy-5,6-dihydrobenzo[c]xanthen-12-ium (HTD) into the microchannels and cavity structures of UiO-66-NH₂, exhibiting two emission maxima at 428 nm and 616 nm, respectively. After introducing fluoride into the system of probe, a drastic fluorescence enhancement at 428 nm was emerged, whereas the emission peak at 616 nm underwent minor fluctuations. The probe that has been developed enables the sensitive and selective detection of fluoride ions, exhibiting excellent linear relationships in the range of 0–100 μM. The detection limit value was estimated to be 6.93 μM. This unique ratiometric luminescence behavior of probe toward fluoride resulted from the creation of hydrogen bonds between fluoride and amino groups in HTD@UiO-66-NH₂. Notably, the probe could utilize as an effective tool for detecting fluoride in cells with high-quality results, which could have important implications for research in biology, toxicology, and related fields. Simultaneously, its corresponding portable online test strips can be easily acquired and employed for fluoride detection through visual colorimetric analysis. The proposed method offers an alternative technology for quantifying fluoride levels in real-life water samples.