3D water-stable europium metal organic frameworks as a multi-responsive luminescent sensor for high-efficiency detection of Cr2O72−, MnO4−, Cr3+ ions and SDBS in aqueous solution

Abstract

A microporous europium metal–organic framework (Eu-MOF), namely, {[Eu₃(bpydb)₃(HCOO)(OH)₂(DMF)]·3DMF·2H₂O}_n (1) with asymmetric trinuclear metal clusters extended by 4,4′-(4,4′-bipyridine-2,6-diyl) dibenzoic acid has been synthesized via the solvothermal method. PXRD of 1 confirms that it possesses excellent water stability and pH stability. The photo-luminescence properties of 1 exhibit effective recognition of Cr₂O₇²⁻, MnO₄⁻, and Cr³⁺ ions and SDBS. Furthermore, a wide linear range, high quenching constant and a low detection limit reveal that 1 can potentially act as a luminescence-based sensor for quantitative and highly sensitive detection of Cr₂O₇²⁻, MnO₄⁻, and Cr³⁺ ions as well as SDBS in aqueous solutions. To the best of our knowledge, the detection limit of 1 is the lowest value reported for Ln-MOF-based luminescent sensors to detect Cr₂O₇²⁻ ions (0.5 μM) in aqueous solutions. The use of a rare earth fluorescent probe for detecting MnO₄⁻ ions is not common. It is the first time that Ln-MOF as a fluorescence probe is used for detecting SDBS. Moreover, fluorescent-based test papers of 1 have also been prepared, which can be helpful to develop visual detection for Cr₂O₇²⁻, MnO₄⁻, and Cr³⁺ ions as well as SDBS in daily applications.