Numerical Recognition System and Ultrasensitive Fluorescence Sensing Platform for Al<sup>3+</sup> and UO<sub>2</sub><sup>2+</sup> Based on Ln (III)-Functionalized MOF-808 via Thiodiglycolic Acid Intermediates
Douchao Mei, Bing Yan
Abstract
Continuous accumulation of Al 3+ in the human body and unintended leakage of UO 2 2+ have posed a great threat to human health and the global environment; thus searching an efficient probe for the detection of Al 3+ and UO 2 2+ is of great importance. Herein, we designed and synthesized two hydrolytically stable Eu 3+ - and Tb 3+ -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 Al 3+ and UO 2 2+ . The detection limit is calculated to be 0.085 ppm for Al 3+ and 0.082 ppm for UO 2 2+ 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 Al 3+, which broadens the potential in real-world sensing applications.