Gas Sorption, Second-Order Nonlinear Optics, and Luminescence Properties of a Series of Lanthanide–Organic Frameworks Based on Nanosized Tris((4-carboxyl)phenylduryl)amine Ligand

Cerium(III) and 5-methylisophthalate-based MOFs with slow relaxation of magnetization and photoluminescence emission

Two novel Ce(III) metal organic frameworks (MOFs) with formulas [Ce(5Meip)(H-5Meip)]nGR-MOF-17 and [CeCl(5Meip)(DMF)]nGR-MOF-18 (5Meip = 5-methylisophthalate, DMF = N,N-dimethylformamide) have been synthesized, forming 3-dimensional frameworks. Magnetic measurements show that both compounds present field-induced slow magnetic relaxation under a small applied dc field. For GR-MOF-17, the temperature dependence of relaxation times is best described by a Raman mechanism, whereas for GR-MOF-18, relaxation occurs through a combination of Raman and local-mode pathways. Moreover, when avoiding short Ce⋯Ce interactions by magnetic dilution in GR-MOF-17@La and GR-MOF-18@La, only the local-mode mechanism is responsible for magnetic relaxation. Photophysical studies show the occurrence of ligand-centred luminescence in both compounds and phosphorescence emission at low temperature for GR-MOF-17.

Fresh hetero-metallic compound as luminescent sensor for detection of CS2 and inhibitory activity on children diabetes

The combination of the dicarboxylate ligand of 2-aminoterephthalic acid (H₂L), Cd(NO₃)₂·4H₂O, and KNO₃ under hydrothermal condition formed a fresh hetero-metallic coordination polymer, namely, [CdK₂(L)₂(H₂O)₄]_n (1). The compound exhibited a high luminescence intensity at normal environment as well as high sensitivity and selectivity in the measurement of CS₂. The effect of the fresh compound on childhood diabetes was investigated. A blood glucose monitor was utilized to assess the blood glucose level of the body after the addition of the compound. Moreover, the relative expression level of the insulin recipient on hepatocytes was assessed by real time RT-PCR.

Homochiral porous coordination polymer of EuIII for metal ion sensing and enantioselective adsorption

A novel multifunctional homochiral porous metal–organic framework was obtained by combining the luminescent component Eu(iii) with an enantiopure triangular polycarboxylic ligand.

A New (3, 6)-Connected Heterometallic Coordination Polymer: Therapeutic and Protective Effect on Ischemic Cerebral Infarction

Solvothermal reaction of 4,4’,4’-nitrilotribenzoic acid (H3TCA) with Ca(NO3)2·4H2O and Cd(NO3)2·4H2O successfully afforded a heterometallic compound, that is, [Cd2Ca(TCA)2(DMA)2(H2O)3]n·2n(DMA) (1, DMA = N,N’-dimethylacetamide). The structure of 1 was further characterized through EA, diffraction of single crystal X-ray, and thermogravimetric analysis (TGA) together with powder X-ray diffraction (PXRD). Moreover, complex 1’s luminescent performance in solid state was also discussed at environmental temperature. The applications on the ischemic cerebral infarction therapy were evaluated, and the specific mechanism was investigated at the same time. Firstly, the hypersensitivity C-reactive protein (hs-CRP) content in human brain microvascular endothelial cell (HBMEC) was measured with real-time reverse transcription-polymerase chain reaction (RT-PCR). Then, interleukin-18 and interleukin-1β content released through the HBMEC was detected with enzyme-linked immunosorbent assay (ELISA).

Structural Variation and Switchable Nonlinear Optical Behavior of Metal-Organic Frameworks

Two europium metal-organic frameworks (MOFs) based on the same ligand, named as ZJU-23-Eu and ZJU-24-Eu, are selectively synthesized by fine-tuning solvent contents to tailor the coordination modes. Eu atoms are eight-coordinated and nine-coordinated in ZJU-23-Eu and ZJU-24-Eu respectively, and their frameworks vary in both spatial connectivity and symmetry. The ligand not only has multiphoton response but also suitable triplet energy level (19 998 cm^-1 ) to sensitize Eu³⁺ . Thus ZJU-23-Eu exhibits characteristic emission of Eu³⁺ peaking at 614 nm via the energy transfer from the two-/three-photon excited ligand to Eu³⁺ , with its bidimensional layered structure benefiting this process. In contrast, the changed spatial connectivity in tridimensional ZJU-24-Eu narrows the distances between adjacent Eu³⁺ ions and reduces the density, resulting in poor two-photon excited fluorescence. Besides, noncentrosymmetric ZJU-24-Eu shows second harmonic generation (SHG) response with an intensity of ≈6.2 times relative to KH₂ PO₄ (KDP) microcrystalline powder while centrosymmetric ZJU-23-Eu cannot. These results have established two nonlinear optical (NLO) models based on MOFs to synchronously analyze the effects of two structural variables on different NLO behaviors, and provide ingenious ways to design MOF-based NLO devices with function on demand.

The chemistry of Ce-based metal-organic frameworks

Metal-organic frameworks (MOFs) have gained widespread attention due to their modular construction that allows the tuning of their properties. Within this vast class of compounds, metal carboxylates containing tri- and tetravalent metal ions have been in the focus of many studies due to their often high thermal and chemical stabilities. Cerium has a rich chemistry, which depends strongly on its oxidation state. Ce(iii) exhibits properties typically observed for rare earth elements, while Ce(iv) is mostly known for its oxidation behaviour. In MOF chemistry this is reflected in their unique optical and catalytic properties. The synthetic parameters for Ce(iii)- and Ce(iv)-MOFs also differ substantially and conditions must be chosen to prevent reduction of Ce(iv) for the formation of the latter. Ce(iii)-MOFs are usually reported in comprehensive studies together with those constructed with other RE elements and normally they are isostructural. They exhibit a greater structural diversity, which is reflected in the larger variety of inorganic building units. In contrast, the synthesis conditions of Ce(iv)-MOFs were only recently (2015) established. These lead selectively to hexanuclear Ce-O clusters that are well-known for Zr-MOFs and therefore very similar structural and isoreticluar chemistry is found. Hence Ce(iv)-MOFs exhibit often high porosity, while only a few porous Ce(iii)-MOFs have been described. Some of these show structural flexibility which makes them interesting for separation processes. For Ce(iv)-MOFs the redox properties are most relevant. Thus, they are intensively discussed for catalytic, photocatalytic and sensing applications. In this perspective, the synthesis, structural chemistry and properties of Ce-MOFs are summarized.

Rare-earth metal–organic frameworks: from structure to applications

In the past 30 years, rare-earth metal–organic frameworks (MOFs) have been gaining attention owing to their diverse chemical structures, and tunable properties.

Structures of Metal-Organic Frameworks with Rod Secondary Building Units

Rod MOFs are metal-organic frameworks in which the metal-containing secondary building units consist of infinite rods of linked metal-centered polyhedra. For such materials, we identify the points of extension, often atoms, which define the interface between the organic and inorganic components of the structure. The pattern of points of extension defines a shape such as a helix, ladder, helical ribbon, or cylinder tiling. The linkage of these shapes into a three-dimensional framework in turn defines a net characteristic of the original structure. Some scores of rod MOF structures are illustrated and deconstructed into their underlying nets in this way. Crystallographic data for all nets in their maximum symmetry embeddings are provided.

From 1D to 3D lanthanide coordination polymers constructed with pyridine-3,5-dicarboxylic acid: synthesis, crystal structures, and catalytic properties

Three series of lanthanide coordination polymers have been synthesized. The structural difference may be derived from the lanthanide contraction. Moreover, we also discussed the size-selective catalytic activity towards cyanosilylation of aldehydes.

Multifunctional lanthanide–organic frameworks for fluorescent sensing, gas separation and catalysis

Two lanthanide MOFs have been synthesized based on a novel anthracene-functionality semi-rigid ligand, which show good selective fluorescent sensing capabilities for 4-nitrophenol and Al³⁺.

Two microporous metal–organic frameworks constructed from trinuclear cobalt(ii) and cadmium(ii) cluster subunits

This work presents two novel microporous metal–organic frameworks which are constructed from a tetracarboxylate ligand and trinuclear cobalt(ii) and cadmium(ii) cluster subunits.

3,5-Bis((4′-carboxylbenzyl)oxy)benzoilate-based coordination polymers: their synthesis, structural characterization, and sensing properties

The structural characterization of four 3,5-bis((4′-carboxylbenzyl)oxy)benzoilate-based coordination polymers has been reported, and the sensing ability of 2 and 4 on NB has been investigated.

A porous lanthanide metal–organic framework based on a flexible cyclotriphosphazene-functionalized hexacarboxylate exhibiting selective gas adsorption

This work presents a rare example of a permanently porous Ln-MOF based on a flexible hexacarboxylate exhibiting selective gas adsorption.

Exploring biphenyl-2,4,4′-tricarboxylic acid as a flexible building block for the hydrothermal self-assembly of diverse metal–organic and supramolecular networks

This contribution reports the hydrothermal self-assembly synthesis, characterization, thermal stability, structural and topological features, and luminescence or magnetic properties of a new series of nine coordination compounds.