Numerical Recognition System and Ultrasensitive Fluorescence Sensing Platform for Al³⁺ and UO₂²⁺ Based on Ln (III)-Functionalized MOF-808 via Thiodiglycolic Acid Intermediates

Continuous accumulation of Al3+ in the human body and unintended leakage of UO22+ have posed a great threat to human health and the global environment; thus searching an efficient probe for the detection of Al3+ and UO22+ is of great importance. Herein, we designed and synthesized two hydrolytically stable Eu3+- and Tb3+-functionalized MOF materials Eu@MOF-808-TDA and Tb@MOF-808-TDA via thiodiglycolic acid (TDA) intermediates by the postsynthetic modification method. Among them, Tb@MOF-808-TDA was applied to construct numerical recognition systems of multiples of three and four by the combination of fluorescent signals, hierarchical cluster analysis, and logical gates. In addition, Tb@MOF-808-TDA exhibits good selectivity and sensitivity for the detection of Al3+ and UO22+. The detection limit is calculated to be 0.085 ppm for Al3+ and 0.082 ppm for UO22+ in aqueous solutions, which is lower than or close to that of latest reported Ln-MOFs. Moreover, the probe shows excellent hydrolytic stability and luminescence stability in the pH range of 4–11, further providing solid evidence for the practical application of Tb@MOF-808-TDA. More importantly, a mixed matrix hydrogel PVA-Tb@MOF-808-TDA was prepared to achieve the visual detection of Al3+, which broadens the potential in real-world sensing applications