Synthesis, Structures, and Magnetic Properties of Two Cobalt(II) Isophthalate Coordination Polymers

Seven new metal-organic frameworks assembled from semi-rigid polycarboxylate and auxiliary N-donor ligands: syntheses, structures and properties

Seven new metal-organic frameworks (MOFs), namely, [Zn₂(L¹)(H₂O)₃]_n (1), [Zn₂(L¹)(dib)(H₂O)₂]_n (2), {[Zn₂(L¹)(4,4'-bipy)(H₂O)₂]·H₂O}_n (3), [Cd₂(L¹)(1,10-phen)]_n (4), [Ni₂(HL¹)(4,4'-bipy)(μ₃-OH)(μ₂-H₂O)]_n (5), {[Co₄(L¹)(4,4'-bibp)₃]·(4,4'-bibp)₃}_n (6), and [Co₂(L²)(4,4'-bibp)₂(H₂O)]_n (7), where H₄L¹ and H₄L² are semi-rigid 3-(3,5-dicarboxylphenoxy)phthalic acid and 4-(3,5-dicarboxylphenoxy)phthalic acid, respectively, and 4,4'-bipy is 4,4'-bipyridine, dib is 1,4-bis(1H-imidazol-1-yl)benzene, 1,10-phen is 1,10-phenanthroline and 4,4'-bipb is 1,4-bis(pyridin-4-yl)benzene, have been prepared under solvothermal conditions with Zn^II, Cd^II, Co^II and Ni^II ions in the presence of auxiliary N-donor ligands. The crystal structures and photoluminescence and magnetic properties of these compounds have been investigated. Compound 1 displays a 3,4,6-connected two-dimensional (2D) topology with a Schläfli symbol of (4².5)₂(4³.5².7)(4⁵.5⁶.6³)₂, and the 2D structure was further assembled to form a three-dimensional (3D) framework by intermolecular O-H...O hydrogen bonds. Compound 2 features a novel 3,3,4-connected structure and the point symbol is (4.10²)(4.6.8⁴)(6².8). Compound 3 exhibits a 3,4,6-connected 3-nodal net having a 3,4,6 T53 type topology, with the point symbol (4.6²)₂(4².6⁴)₂(4².6⁸.8².10³). Compound 4 shows a 2D→3D supramolecular structure formed by π-π stacking interactions. Compound 5 possesses a 3D framework with a tfz-d net topology. Compounds 6 and 7 are constructed from the same auxiliary ligand and metal salt at the same temperature, but with different main ligands and exhibiting different topologies. Compound 6 presents a 3D 4,6-connected topological network with a Schläfli symbol of (3.4⁴.6)(3².4⁴.5⁶.6³), while compound 7 has a 3D topological network with a Schläfli symbol of (4¹².6¹⁶). Magnetic analyses indicate that compounds 5 and 7 show weak antiferromagnetic interactions.

Honeycomb Metal-Organic Framework with Lewis Acidic and Basic Bifunctional Sites: Selective Adsorption and CO2 Catalytic Fixation

Carrying out the strategy of incorporating rod secondary building units and polar functional groups in metal-organic frameworks (MOFs) to accomplish the separation of CO₂ and C₂ hydrocarbons over CH₄ as well as CO₂ fixation, an oxalamide-functionalized ligand N, N'-bis(isophthalic acid)-oxalamide (H₄BDPO) has been designed. The solvothermal reaction of H₄BDPO with the oxophilic alkaline-earth Ba²⁺ ion afforded a honeycomb Ba-MOF, {[Ba₂(BDPO)(H₂O)]·DMA} _n (1). Due to the existence of Lewis basic oxalamide groups and unsaturated Lewis acid metal sites in the tubular channels, the activated framework presents not only high C₂H₆, C₂H₄, and CO₂ uptakes and selective capture from CH₄, but also efficient CO₂ chemical fixation as a recyclable heterogeneous catalyst. Grand canonical Monte Carlo simulations were combined to explore the adsorption selectivities for C₂H₆-CH₄ and C₂H₄-CH₄ mixtures as well as the interaction mechanisms between the framework and epoxides.

Solvent-dependent selective cation exchange in anionic frameworks based on cobalt(ii) and triphenylamine linkers: reactor-dependent synthesis and sorption properties

Two anionic cobalt(ii) MOFs were obtained dependent on the reactor design and show a solvent-dependent cation exchange leading to a remarkable increase in the surface area of post-synthetic modified materials.