Multifunctional Ln–MOF Luminescent Probe for Efficient Sensing of Fe3+, Ce3+, and Acetone

A new series of five three-dimensional Ln(III) metal–organic frameworks (MOFs) formulated as [Ln4(μ6-L)2(μ-HCOO)(μ3-OH)3(μ3-O)(DMF)2(H2O)4]n {Ln3+ = Tb3+ (1), Eu3+ (2), Gd3+ (3), Dy3+ (4), and Er3+ (5)} was successfully obtained via a solvothermal reaction between the corresponding lanthanide(III) nitrates and 2-(6-carboxypyridin-3-yl)terephthalic acid (H3L). 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 [Ln4(μ3–OH)3(μ3-O)(μ-HCOO)]6+ blocks and μ6-L3– 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 (Fe3+ or Ce3+) 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 Ce3+ or Fe3+ cations or acetone molecules.