Efficient and selective sensing of Cu and UO by a europium metal-organic framework.

We report here the investigation of using a luminescent europium organic framework, [Eu(MTBC)(OH)(DMF)(HO)]·2DMF·7HO (denoted as compound 1), for detecting of both Cu and UO with high sensitivity. Based on the spectroscopy analysis, compound 1 could selectively respond to Cu and UO ions among other selected monovalent, divalent, trivalent metal cations based on a turn-off mechanism. The detection limit of compound 1 towards Cu ion was as low as 17.2 μg/L, which is much lower than the maximum tolerable concentration of Cu in drinking water (2 mg/L) defined by United States Environmental Protection Agency. On the other hand, the detection limit towards UO 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 Cu and UO ions, provides insight into developing MOF-based multifunctional sensors for both nonradioactive and radioactive elements.