micro-/nanoscales and under strong electromagnetic fields. [2] It has thus attracted much attention. Examples of ratiometric luminescent thermometers include upconversion nanoparticles, chelate complexes, host-guest composites, polymers, and metal-organic frameworks (MOFs). [3] MOFs are particularly appropriate for luminescence thermometry because their variable metal centers, organic linkers, and guest species provide a wide range of opportunities for engineering luminescent properties. [4] The intrinsic luminescent properties of lanthanide ions in the MOFs have further broadened their applications in temperature sensing. In 2012, Qian and co-workers demonstrated the first selfcalibrating lanthanide-MOF thermometer for cryogenic temperatures by making use of the temperature-dependent luminescent intensities of Tb 3+ and Eu 3+ ions in the same framework. [5] Subsequently, much attention has been given to the fabrication of high-performance lanthanide-MOF temperature sensors operating in different temperature regimes. [6] Despite the progress, such mixed lanthanide-MOF approach is limited to utilizing the characteristic emissions of lanthanide ions. However, apart from the luminescence of MOF's variable lanthanide nodes and organic linkers, guest species (e.g., organic dyes, quantum dots, and chromophores) accommodated in the host framework can also serve as the luminescence centers and further contribute to their optical properties. [7] If two luminescent guest units with different emission bands can be embedded into porous MOFs and form dual-emitting composites, we can take advantage of the temperature-dependent intensities of the two luminescent guest units to construct novel solid luminescent composites for temperature sensing. Moreover, since the energy transfer between the two guest species is determined by spectral overlap of the donor and accepter and can be tailored by combining different luminescent guests, many types of ratiometric composites covering a wide working range and sensitivity can be obtained. [8] In addition to these considerations, it is particularly necessary to point out that most of currently reported MOF-based temperature sensing materials are in powder form, which has drawbacks such as difficulty in uniformly distributing the powdered MOF crystals on the surface of microelectronic devices and spatially resolve/imaging their temperature fluctuations. Furthermore, since the crystalline MOFs are not as flexible as soft thin-film materials, MOF particles cannot be integrated Accurate measurement of temperature is crucial in many branches of medicine, science, and engineering, and often requires temperature sensors that are noninvasive, of high accuracy, and can spatially resolve thermal fluctuations at the nanoscale. Here a new type of flexible and tailorable mixed-matrix membranes (MMMs) is introduced, which feature dual-emitting metalorganic framework (MOF)-based nanocomposites embedded in polymer matrix, and its potential use in luminescence temperature sensing is evaluated. The ...

Metal-organic frameworks (MOFs), as an emerging kind of porous materials, excels in designability, regulatability, and modifiability in terms of composition, topology, pore size, and surface chemistry, thus affording a huge...

Detection of H2S in the biological system has attracted enormous attention in recent years. In this work, a new vinyl-functionalized metal–organic framework (MOF), [(Me2NH2)2] [Eu6(μ3-OH)8(BDC–CHCH2)6(H2O)6] (Eu-BDC–CHCH2, BDC–CHCH2 = 2-vinylterephthalic acid), was synthesized under solvothermal conditions. The vinyl groups in the ligands can not only modulate the “antenna effect” of the ligand on Eu3+ ions but also serve as an exposed reactive site to allow for the quantitative detection of H2S by Eu-BDC–CHCH2. The ratiometric fluorescent probe has the advantages of water stability, acid-base stability (pH = 2–11), fast response (<2 min), high selectivity, and sensitivity (LOD = 38.4 μM). We also used Eu-BDC–CHCH2 to detect and analyze H2S in tap and lake waters, demonstrating the potential of the probe for biological and environmental applications. In addition, the MOF-based agarose hydrogel film allows for the visual detection of H2S via a smartphone by identifying the RGB values. The vinyl-functionalized MOF can thus be a powerful sensing platform for H2S.

Excessive content of fluoride ions (F − ) in water will lead to water pollution and endanger human health, so the research on the method of low-cost, rapid, and efficient detection of F − is of particular significance. In this work, an amino-functionalized ligand with an appropriate triplet energy excited state, 2′-amino-[1,1′:4′,1″-terphenyl]-3,3″,5,5″-tetracarboxylic acid (H 4 TPTC-NH 2 ), was selected to construct a luminescent single-lanthanide metal−organic framework, EuTPTC-NH 2 , with uncoordinated amino groups for the detection of F − . Based on host−guest interactions, that is, hydrogen bonds formed between the free amino groups and F − ions, EuTPTC-NH 2 was developed as a ratiometric fluorescence probe for F − detection with good antiinterference ability, low detection limit, high water stability, and selectivity. It was found that EuTPTC-NH 2 has an excellent linear response to F − in the concentration range of 0−80 μM with high sensitivity and a low detection limit of 11.26 μM. A hydrogel membrane based on the combination of EuTPTC-NH 2 and agarose was also prepared for the quantitative visual detection of F − in water.

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