A new series of five three-dimensional Ln(III) metal-organic frameworks (MOFs) formulated as [Ln(μ-L)(μ-HCOO)(μ-OH)(μ-O)(DMF)(HO)] {Ln = Tb (1), Eu (2), Gd (3), Dy (4), and Er (5)} was successfully obtained via a solvothermal reaction between the corresponding lanthanide(III) nitrates and 2-(6-carboxypyridin-3-yl)terephthalic acid (HL). All of the obtained compounds were fully characterized, and their structures were established by single-crystal X-ray diffraction. All products are isostructural and possess porous 3D networks of the fluorite topological type, which are driven by the cubane-like [Ln(μ-OH)(μ-O)(μ-HCOO)] blocks and μ-L spacers. Luminescent and sensing properties of 1-5 were investigated in detail, revealing a unique capability of Tb-MOF (1) for sensing acetone and metal(III) cations (Fe or Ce) with high efficiency and selectivity. Apart from a facile recyclability after sensing experiments, the obtained Tb-MOF material features a remarkable stability in a diversity of environments such as common solvents, aqueous solutions of metal ions, and solutions with a broad pH range from 4 to 11. In addition, compound 1 represents a very rare example of the versatile Ln-MOF probe capable of sensing Ce or Fe cations or acetone molecules.
A novel luminescent microporous lanthanide metal-organic framework (Ln-MOF) based on a urea-containing ligand has been successfully assembled. Structural analysis revealed that the framework features two types of 1D channels, with urea N-H bonds projecting into the pores. Luminescence studies have revealed that the Ln-MOF exhibits high sensitivity, good selectivity, and a fast luminescence quenching response towards Fe , Cr anions, and picric acid. In particular, in the detection of Cr O and picric acid, the Ln-MOF can be simply and quickly regenerated, thus exhibiting excellent recyclability. To the best of our knowledge, this is the first example of a multi-responsive luminescent Ln-MOF sensor for Fe , Cr anions, and picric acid based on a urea derivative. This Ln-MOF may potentially be used as a multi-responsive regenerable luminescent sensor for the quantitative detection of toxic and harmful substances.
In this study, a good core-shell heterostructure of Pt NPs@UiO-66 was fabricated by encapsulating presynthesized platinum nanoparticles (Pt NPs) into the host matrix of UiO-66 which possesses the slender triangular windows with a diameter of 6 Å. The transmission electron microscopy images exhibited that the number of the encapsulated Pt NPs and the crystalline morphology of as-synthesized core-shell heterostructure samples had a series of changes with increasing the volume of the injected Pt NPs precursor solution. Among these samples, the Pt NPs@UiO-66-2 sample had a good crystalline morphology with several well-dispersed Pt NPs encapsulated in UiO-66 frameworks. But there were no obvious Pt NPs observed in the Pt NPs@UiO-66-1 sample, and for the Pt NPs@UiO-66-3 sample, the number of Pt NPs encapsulated in UiO-66 matrix notably reduced and the metal organic framework (MOF) crystals became small and aggregated. The electrochemical measurements showed that the Pt NPs@UiO-66-2 sample modified glass carbon electrode (GCE) presented a remarkable electrocatalytic activity toward hydrogen peroxide (H2O2) oxidation, including an excellent anti-interference performance even if the concentration of the interference species was the same as the H2O2, an extended linear range from 5 μM to 14.75 mM, a low detection limit, as well as good stability and reproducibility. The results indicate the superiority of MOFs in H2O2 detection. And more importantly, it will provide a new opportunity to promote the anti-interference performance of the nonenzyme electrochemical sensors.
A highly sensitive and selective fluorescent probe for inorganic and organic mercury species displays colorimetric and ratiometric response in a buffer solution via mercury promoted cleavage reaction. The probe is demonstrated to detect CH(3)HgCl in living cells.
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