Efficient and selective sensing of Cu2+ and UO22+ by a europium metal-organic framework

Publication date: 1 May 2019

Source: Talanta, Volume 196

Author(s): Wei Liu, Yanlong Wang, Liping Song, Mark A. Silver, Jian Xie, Linmeng Zhang, Lanhua Chen, Juan Diwu, Zhifang Chai, Shuao Wang

Abstract

We report here the investigation of using a luminescent europium organic framework, [Eu₂(MTBC)(OH)₂(DMF)₃(H₂O)₄]·2DMF·7H₂O (denoted as compound 1), for detecting of both Cu²⁺ and UO₂²⁺ with high sensitivity. Based on the spectroscopy analysis, compound 1 could selectively respond to Cu²⁺ and UO₂²⁺ ions among other selected monovalent, divalent, trivalent metal cations based on a turn-off mechanism. The detection limit of compound 1 towards Cu²⁺ ion was as low as 17.2 μg/L, which is much lower than the maximum tolerable concentration of Cu²⁺ in drinking water (2 mg/L) defined by United States Environmental Protection Agency. On the other hand, the detection limit towards UO₂²⁺ ions is 309.2 μg/L, which could be used for detecting uranium in relative severely contaminated areas. The concentration-dependent luminescence intensity evolution process could be fully understood by the absorption kinetics and isotherm investigations. Furthermore, the quenching mechanism was elucidated by the UV-vis, excitation, luminescence, and lifetime studies. Compound 1, as the first MOF based luminescence probe for both Cu²⁺ and UO₂²⁺ ions, provides insight into developing MOF-based multifunctional sensors for both nonradioactive and radioactive elements.

Graphical abstract

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