3d 4f Metal Organic Frameworks Research Articles

Excellent microwave absorption performance of LaFeO3/Fe3O4/C perovskite composites with optimized structure and impedance matching

Compositional optimization and structural design are considered to be effective approaches for improving the microwave absorption (MA) ability of carbon-based absorbers. Herein, we have synthesized the LaFeO3/Fe3O4/C perovskite composites by one-step pyrolysis of 3d-4f metal-organic frameworks (MOFs) at a low temperature. The content of LaFeO3 and Fe3O4 can be efficiently controlled by tuning the pyrolysis temperature. For LaFe-MOF-650 composite, the effective absorption bandwidth (EAB, RLmin ≤ −10 dB) reaches 7.2 GHz at 2.2 mm under a filling ratio of 50 wt%. Further, the effect of hollow and spiral carbon on the MA performance of 3d-4f-MOFs-derived composites is investigated. The minimum reflection loss (RLmin) of the hollow LaFeO3/Fe3O4/C sample with a thickness of 1.82 mm reaches up to −68.3 dB under a filling ratio of 40 wt%. The spiral LaFeO3/Fe3O4/C sample exhibits an RLmin of −42.3 dB and an EAB of 4.70 GHz at an ultra-low thickness of 1.35 mm under a lower filling ratio of 30 wt%. Benefiting from the structural and compositional advantages, the prepared high-efficiency MA materials with optimized impedance matching and attenuation capability are excellent candidates for high-performance MA materials.

A dense 3d–4f metal–organic framework with “gas pockets” for highly efficient CH4/N2separation

A pillar-layered dense 3d–4f MOF shows high IAST selectivity for CH4/N2owing to the enhancement of the interactions between the MOF and CH4by the heteroatoms of the pillars.

Two 3d-4f metal-organic frameworks as fluorescent sensor array for the discrimination of phosphates based on different response patterns

Both organic and inorganic phosphates play important roles in biological activities. Considering the conventional methods are not very useful for identifying them from their analogues, the sensor array strategy has emerged in recent years, which is able to distinguish chemical species with similar structure or chemical properties. We propose a fluorescence sensor array based on two 3d-4f metal-organic frameworks (MOFs) by recording their direct one-step fluorescence changes with the addition of various phosphates. With the introduction of d-metal ions in the sensor unit synthesis process, two 3d-4f MOFs display higher sensitivity and noticeable fluorescence differences to five phosphates than the homometallic MOFs. Phosphates show diverse affinities to sensor units, forming the basis of differential sensing. The signals are much easier to collect, enabling the sensor array to simply accomplish the identification. Through statistical analysis, the sensor array is proved to be excellent in discriminating individual phosphate and mixture. Discrimination of five phosphates is successfully performed in serum samples to illustrate the practicability of the sensor array. This work presents an efficient and reliable approach for simultaneous detection of different phosphates, which can be extended to devise other array-based sensing methods.

A Solvent-Stable Zinc(II)–Gadolinium(III) Metal–Organic Framework Assembled with Furan-2,5-Dicarboxylic Acid: Synthesis, Crystal Structure and Magnetic Property

A novel three-dimensional 3d–4f metal–organic framework (MOF), {[(CH3)2NH2]2[Zn2Gd2(FDA)6(DMF)2]·2DMF}n (Zn–Gd) (H2FDA = furan-2,5-dicarboxylic acid) assembled with furan-2,5-dicarboxylic acid has been isolated and characterized by infrared spectra, elemental analysis, thermogravimetric analysis, powder X-ray diffraction and single-crystal X-ray diffraction. Structure analysis indicates this MOF is an interesting three-dimensional 8-connected bcu body centered cubic topological net. Moreover, Zn–Gd MOF shows a tolerance towards moisture and the corresponding solvents, demonstrating the excellent chemical stability. The magnetic property of Zn–Gd MOF suggests a weak antiferromagnetic coupling interaction between adjacent Gd(III) ions in Zn–Gd MOF.

Tuning the luminescence of two 3d-4f metal-organic frameworks for the fast response and highly selective detection of aniline.

Two 3D solvent-stable zinc(ii)-lanthanide(iii) heterometallic metal-organic frameworks (MOFs) {[(CH3)2NH2]2[Zn2Ln2(FDA)6(DMF)2]·2DMF}n [Ln = Eu (Zn-Eu) and Tb (Zn-Tb); H2FDA = furan-2,5-dicarboxylic acid] based on Zn2Ln2(COO)10 tetrametallic clusters and furan-2,5-dicarboxylic acid have been successfully synthesized. These MOFs can serve as luminescent sensors for the fast response and highly selective detection of aniline via luminescence quenching. More importantly, a linear correlation is observed between their luminescence and the low concentration of aniline and the detection limits of aniline are 7.5 μmol L-1 for Zn-Eu and 5.2 μmol L-1 for Zn-Tb.

3d-4f Metal-Organic Framework with Dual Luminescent Centers That Efficiently Discriminates the Isomer and Homologues of Small Organic Molecules.

A 3d-4f luminescent metal-organic framework (MOF), [Tb2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (4), and three analogues {[La2(Cu8I8)(C12H8NO2)6(C4H8O2)2(H2O)2]·3C4H8O2·2H2O (1), [Ce2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (2), and [Eu2(Cu8I8)(C12H8NO2)6(H2O)4]·5C4H8O2 (3)}, were self-assembled from copper(I) halide clusters and lanthanide metal ions with an organic linker [3-(pyridin-4-yl)benzoic acid] under solvothermal conditions. Compound 4 with high quantum yield (Φ = 68%) exhibits reversible luminescence behavior, accompanying the removal and recovery of guest molecules (1,4-dioxane). Because of the unique porous structure and dual luminescent centers of compound 4, it can efficiently differentiate benzene series with different sizes and provide readouts in corresponding optical signals. Furthermore, it also can unambiguously discriminate the isomers, homologues, and other small molecules with similar structural motifs from one another. The luminescent color of the MOF sensor in different guest solvents has obvious changes that can be clearly distinguished by the naked eye. This multicolor luminescence originates from emissions of the dual luminescent centers, and the emissions have shifted, enhanced, weakened, or quenched to different degrees.

An alkali-ion insertion approach to structurally transform metal–organic frameworks

The insertion of alkali metal ions into a prevalent lanthanide-carboxylate coordination motif in heterometallic 3d–4f metal–organic frameworks (MOFs) leads to new MOFs whose structures are sensitively dependent on the size of the alkali ions used and with significantly enhanced effective free crystallographic volume.

Unique Chiral Interpenetrating d-f Heterometallic MOFs as Luminescent Sensors.

One novel three-dimensional (3D) 3d-4f metal-organic framework (MOF), [TbZn(L)(CO3)2(H2O)]n (1) [HL = 4'-(4-carboxyphenyl)-2,2':6',2″-terpyridine], has been successfully synthesized and structurally characterized. Structural analysis shows that compound 1 features a unique chiral interpenetrating 3D framework for the first time. The resulting crystals of 1 are composed of enantiomers 1a (P41) and 1b (P43), as was clearly confirmed by the crystal structure and the corresponding circular dichroism (CD) analyses of eight randomly selected crystals. The investigations on CD spectra based on every single crystal clearly assigned the Cotton effect signals. The powder X-ray diffraction measurement of 1 after being immersed in common solvents reveals that 1 possess excellent solvent stability. Furthermore, luminescent studies imply that 1 displays highly selective luminescent sensing of aldehydes, such as formol, acetaldehyde, and propanal.

Syntheses, structures and magnetic properties of one family of 3d–4f chiral metal-organic frameworks (MOFs) based on D(+)-camphoric acid

The hydrothermal reactions of D (+)-camphoric acid ( D -H 2 Cam) and 1,10-phenanthroline (phen)/2,2′-bipyridine (2,2′-bipy) with the corresponding metal salts gave rise to eleven chiral 3d–4f heterometallic metal-organic frameworks (MOFs). Single-crystal X-ray diffraction measurements reveal that the crystal structures are isostructural, crystallizing in the orthorhombic space group P 2 1 2 1 2 1 and they exhibit unique three-dimensional chiral 6-connected frameworks involving 1D zigzag chains aligned parallel to the a axis and the 2D wave-like lanthanide layers, with the Schläfli symbol (4 9 · 6 6 ). Moreover, we have systematically investigated the magnetic behaviors of partial compounds. • Eleven chiral 3d-4f MOFs have been synthesized and characterized. • They exhibit unique 6-connected frameworks. • The magnetic behaviors have been systematically investigated. Eleven chiral 3d-4f Metal-Organic Frameworks constructed from D (+)-camphoric acid have been synthesized. The crystal structures exhibit unique three-dimensional chiral 6-connected frameworks. The magnetic behaviors have been systematically investigated.

ChemInform Abstract: Iodine‐Templated Assembly of Unprecedented 3d—4f Metal—Organic Frameworks as Photocatalysts for Hydrogen Generation.

AbstractThe isotypic compounds (III) crystallize in the monoclinic space group P21/c with Z = 2 (single crystal XRD) and exhibit three‐dimensional frameworks with triangular helical channels, which accomodate linear polyiodide chains.

Iodine-templated assembly of unprecedented 3d–4f metal–organic frameworks as photocatalysts for hydrogen generation

Unprecedented 3d-4f MOFs encapsulating infinite linear polyiodide chains were firstly reported using iodine molecules as a versatile precursor template. They possess high framework stability in acid/base aqueous solutions. The kinetics of iodine molecule release/recovery and UV-light photocatalytic H(2) evolution activities were investigated.

Dryness sensitive porous 3d–4f metal–organic framework with unusual dynamic behaviour

A new three-dimensional heteronuclear metal–organic framework has been synthesized using the 1,2,4,5-benzenetetracarboxylate ligand as a linker and Pr(III)–Cu(II) dinuclear units as nodes. The resulting structure shows an unexpected dynamic behaviour, where the volume of the crystal structure is shrunk by 11.5% in a dryness atmosphere.

Dynamic behavior in a dryness sensitive 3d-4fmetal–organic framework

Dynamic behavior in a dryness sensitive 3<i>d</i>-4<i>f</i>metal–organic framework

Construction of Cu(II)–Gd(III) metal–organic framework by the introduction of a small amino acid molecule: hydrothermal synthesis, structure, thermostability, and magnetic studies

A new member of 3d-4f metal–organic framework (MOF), Gd2Cu(μ-H2O)2(ip)4(CH3CH(NH3)CO2)2·H2O (1, ip = 1,3-benzene dicarboxylate), was generated by the hydrothermal self-assembly of Gd2O3, CuCl2, H2ip, and L-alanine. In 1, the slightly distorted CuO4 squares combine with GdO9 polyhedra via ip and CH3CH(NH3)CO2 carboxyl groups to create the Gd2Cu(CO2)8(CH3CH(NH3)CO2)2 rod-like substructure; such species are further linked together by phenyl units of ip to give the pcu-type rod packing. The subsequent topology analysis based on O'Keeffe's definition and classification of rod-based MOFs suggests the irl net of 1. Moreover, as evidenced by TG and XRD research, the potential microporous structure that owns the solvent-accessible volume of 246 A3, equal to 5.7% of the cell volume, can be maintained until 285 °C after the loss of coordinated water molecules. The magnetic measurements suggest weak ferromagnetic interactions within the Gd2Cu(CO2)8(CH3CH(NH3)CO2)2 rod-like substructure, which is estimated by the fitting of χM = C/(T-θ) with θ = +0.2K and a simplified Gd–J–Cu–J–Gd mode with J = +0.23 cm−1, g = 2.0, TIP = 100 × 10−6 cm3 mol−1K.