Diversity of lanthanide(III)-2,5-dihydroxy-1,4-benzenedicarboxylate extended frameworks: syntheses, structures, and magnetic properties

Rationally Reconstructed Metal-Organic Frameworks as Robust Oxygen Evolution Electrocatalysts

Reconstructing metal-organic framework (MOFs) toward a designed framework structure provides breakthrough opportunities to achieve unprecedented oxygen evolution reaction (OER) electrocatalytic performance, but has rarely, if ever, been proposed and investigated yet. Here, the first successful fabrication of a robust OER electrocatalyst by precision reconstruction of an MOF structure is reported, viz., from MOF-74-Fe to MIL-53(Fe)-2OH with different coordination environments at the active sites. Due to the radically reduced e_g -t_2g crystal-field splitting in Fe-3d and the much suppressed electron-hopping barriers through the synergistic effects of the O species the efficient OER of in MIL-53(Fe)-2OH is guaranteed. Benefiting from this desired electronic structure, the designed MIL-53(Fe)-2OH catalyst exhibits high intrinsic OER activity, including a low overpotential of 215 mV at 10 mA cm^-2 , low Tafel slope of 45.4 mV dec^-1 and high turnover frequency (TOF) of 1.44 s^-1 at 300 mV overpotential, over 80 times that of the commercial IrO₂ catalyst (0.0177 s^-1 ).Consistent with the density functional theory (DFT) calculations, the real-time kinetic simulation reveals that the conversion from O* to OOH* is the rate-determining step on the active sites of MIL-53(Fe)-2OH.

Crystal structure of poly[diaqua-(μ 2-2,5-dihydroxyterephthalato-κ2 O:O′)(μ 2-bis(4-pyridylformyl)piperazine-κ2 N:N′)cadmium(II)] dihydrate, C24H28CdN4O12

C24H28CdN4O12, monoclinic, P21/c (no. 14), a = 11.0801(4) Å, b = 8.3925(3) Å, c = 13.9503(5) Å, β = 102.810(3)°, Z = 2, V = 1353.89(8) Å3, R gt (F) = 0.0273, wR ref (F 2) = 0.0633, T = 291 K.

Heteroleptic LaIII Anilate/Dicarboxylate Based Neutral 3D-Coordination Polymers

Three new 3D metal-organic frameworks of lanthanum based on mixed anionic ligands, [(La2(pQ)2(BDC)4)·4DMF]n, [(La2(pQ)2(DHBDC)4)·4DMF]n, [(La2(CA)2(BDC)4)·4DMF]n (pQ-dianion of 2,5-dihydroxy-3,6-di-tert-butyl-para-quinone, CA-dianion of chloranilic acid, BDC-1,4-benzenedicarboxylate, DHBDC-2,5-dihydroxy-1,4-benzenedicarboxylate and DMF-N,N'-dimethylformamide), were synthesized using solvothermal methodology. Coordination polymers demonstrate the rare xah or 4,6T187 topology of a 3D framework. The homoleptic 2D-coordination polymer [(La2(pQ)3)·4DMF]n was obtained as a by-product in the course of synthetic procedure optimization. The thermal stability, spectral characteristics and porosity of coordination polymers were investigated.

Synthesis, crystal structures and, magnetic and photoluminescence properties of lanthanide-based metal-organic frameworks constructed with 2,5-dihydroxybenzene-1,4-dicarboxylic acid

Four new lanthanide(iii) coordination polymers (1-4) have been synthesized by using 2,5-dihydroxybenzene-1,4-dicarboxylate (Dhbdc, C8H6O6 2-) as a ligand and characterized by elemental analysis, infrared spectroscopy, TGA-DSC (Thermogravimetric Analysis-Differential Scanning Calorimetry) and single crystal X-ray diffraction studies. The isolated complexes include; [Ce(Dhbdc)(H2O)3Cl] n (1) and [Ln(Dhbdc)1.5(H2O)2] n ·3n(C2H6O)·nH2O [Ln = Eu (2), Gd (3) and Tb (4)]. The structural analysis reveals that compound 1 is a two-dimensional polymer in which the cerium atoms are coordinated by six oxygen and two bridging chloride ions adopting a dodecahedral geometry. The compounds 2-4 are isomorphous and their extended structures consist of three-dimensional supramolecular frameworks encapsulating [001] channels occupied by the guest water and ethanol molecules. The metal atoms in 2-4 exhibit a square antiprism geometry. All these compounds have O-H⋯O hydrogen bonds originating from the coordinated water and solvent molecules that help to consolidate the structures. The compounds 1, 3 and 4 were investigated for magnetic properties and they exhibited weak antiferromagnetic coupling interactions between the lanthanides as per the Curie Weiss law. Anisotropic nature of 3 and 4 has been depicted as per magnetization versus field plots. Complex 4 behaves as a soft magnetic material as compared to 3. The luminescence studies indicate that compounds 2, 3 and 4 show ligand-centred fluorescence, which is significantly enhanced in the case of 4.

From partial to complete neutralization of 2,5-dihydroxyterephthalic acid in the Li–Na system: crystal chemistry and electrochemical behavior of Na2Li2C8H2O6vs.Li

The 2,5-dihydroxyterephthalic acid (H₄-p-DHT) is of special interest in the field of materials science because of the two symmetric sets of oxygen donor functional groups (i.e., β-hydroxy acid moieties).

Single-crystal-to-single-crystal post-synthetic modifications of three-dimensional LOFs (Ln = Gd, Eu): a way to modulate their luminescence and thermometric properties

Single-crystal-to-single-crystal post-synthetic modifications of {[Ln₂(H₂L)₃(DMF)₄]·2DMF}_n LOFs (Ln = Gd, Eu) to modulate their luminescence and thermometric properties.

Water-Stable Europium 1,3,6,8-Tetrakis(4-carboxylphenyl)pyrene Framework for Efficient C2H2/CO2 Separation

Compound {(Me₂NH₂)₃[Eu₇(μ₃-O)₂(TBAPy)₅(H₂O)₆]·12.5DMF} _n (JXNU-5), constructed from the 1,3,6,8-tetrakis(4-carboxylphenyl)pyrene (TBAPy^4-) ligand and one-dimensional (1D) europium carboxylate rods, is presented. JXNU-5 has a three-dimensional framework with 1D channels. The strong coordination bonds between Eu^III ions with high charge densities and carboxylate O atoms as well as strong π···π-stacking interactions between pyrenes lead to a water-resistant JXNU-5, which was verified by powder X-ray diffraction and surface area measurements. The breakthrough simulations and experiments demonstrate that an efficient C₂H₂/CO₂ (50/50 mixture) gas separation at ambient conditions was achieved with JXNU-5. The calculation results show that the dominating interactions between the absorbed C₂H₂ molecules and host framework are hydrogen bonds associated with the carboxylate O atoms exposed on the pores. Thus, an elegant example of a water-stable metal-organic framework for effective C₂H₂/CO₂ separation is demonstrated.

Crystal structure of catena-poly[diaqua-(μ2-2,5-dihydroxyterephthalato-κ4O,O′:O′′,O′′′)cadmium(II)], C8H8O8Cd

C8H8O8Cd, monoclinic, C2/c (no. 15), a = 16.5170(11) Å, b = 5.4639(3) Å, c = 11.5875(9) Å, β = 108.992(8)°, V = 988.81(12) Å3, Z = 4, Rgt(F) = 0.0196, wRref(F2) = 0.0510, T = 286.74(11) K.

The diversities of magnetic behaviors appearing simultaneously in three isomorphs based on 1H-tetrazolyl-acetic acid ligand

There isomorphous complexes with 1H-tetrazolyl-acetic acid (TAA) have been synthesized, showing diverse magnetic properties: typical antiferromagnetic for 1, ferromagnetic for 2 and the spin glass behaviour for 3.

Microwave-assisted ionothermal synthesis of a water-stable Eu-coordination polymer: a Ba2+ ion detector and fluorescence thermometer

Presented is a water-stable Eu-coordination polymer, namely [HMIm]Eu(DHBDC)₂, capable of detecting Ba²⁺ in aqueous solution and acting as a two-PL transition fluorescence thermometer.

Neodymium 1D systems: targeting new sources for field-induced slow magnetization relaxation

Two non-isostructural homometallic 1D neodymium species displaying field-induced slow magnetization relaxations are presented together with theoretical studies. It is established that both systems are better described as organized 1D single molecule magnets (SMMs).

Three sra topological lanthanide–organic frameworks built from 2,2′-dimethoxy-4,4′-biphenyldicarboxylic acid

The first neutral 3D sra-LOF built from a 1D inorganic rod-shaped chain [Ln(CO₂)₂(HCO₂)]_n (Ln = Eu, Gd, Dy) was synthesized.

Three novel lanthanide metal-organic frameworks (Ln-MOFs) constructed by unsymmetrical aromatic dicarboxylatic tectonics: synthesis, crystal structures and luminescent properties

Three novel Ln(III)-based coordination polymers, {[Ln₂ (2,4-bpda)₃ (H₂O)_x]·yH₂O}_n (Ln = La (III) (1), x = 2, y = 0, Ce (III) (2), Pr (III) (3), x = 4, y = 1) (2,4-H₂bpda = benzophenone-2,4-dicarboxylic acid) have been prepared via a solvothermal method and characterized by elemental analysis, IR, and single-crystal X-ray diffraction techniques. Complex 1 exhibits a 3D complicated framework with a new 2-nodal (3,7)-connected (4²·5) (4⁴·5¹·6⁶·8) topology. Complexes 2 and 3 are isomorphous, and feature a 3D 4-connected (6⁵·8)-CdSO₄ network. Moreover, solid-state properties such as thermal stabilities and luminescent properties of 1 and 2 were also investigated. Complex 1 crystallized in a monoclinic space group P2₁/c with a = 14.800 (3), b = 14.500 (3), c = 18.800 (4) Å, β = 91.00 (3), V = 4033.9 (14) ų and Z = 4. Complex 2 crystallized in a monoclinic space group Cc with a = 13.5432 (4), b = 12.9981 (4), c = 25.7567 (11) Å, β = 104.028 (4), V = 1374.16 (7) ų and Z = 4.

Syntheses, topologies, and luminescence of four Ln–organic polymers constructed from aromatic tetracarboxylic acids

Four interesting Ln coordination polymers based on tetracarboxylate acids have been hydrothermally synthesized through the linker extension strategy.