Synthesis, structure, topology and magnetic properties of cobalt(ii) coordination polymers with 2-nitrobiphenyl-4,4′-dicarboxylic acid and bis(pyridyl) ligands

Different Phenomena in Magnetic/Electrical Properties of Co(II) and Ni(II) Isomorphous MOFs

Two unprecedented and stable metal-organic frameworks, {[Co₂(H₂O)₂(L)(OH)]·2.5H₂O·0.5DMF} _n (1) and {[Ni₂(H₂O)₂(L)(OH)]·1.75H₂O} _n (2), have been synthesized (H₃L = 5-(5-carboxy-pyridin-3-yloxy)-isophthalic acid, DMF = N,N-dimethylformamide). Structural analysis shows that 1 and 2 are heteronuclear isomorphous, possessing a three-dimensional (3D) (4,8)-connected flu/fluorite topological framework formed through the interconnection of tetranuclear butterfly {M₄(COO)₆(OH)₂} clusters and the ligands. Although the frameworks of these two compounds are similar, their magnetic properties are different. Compound 1 exhibits an antiferromagnetic interaction in the high-temperature region, while 2 shows a weak ferromagnetic interaction in the whole-temperature region. Furthermore, considering the presence of hydroxyl groups and water molecules in the frameworks, we tested their proton conductivity. The efficient proton transfer pathway in the framework endowed 1 and 2 with excellent proton conductivities of 9.07 × 10^-5 and 1.29 × 10^-4 S·cm^-1 at 363 K and 98% relative humidity (RH), respectively.

Three 3D LnIII-MOFs based on a nitro-functionalized biphenyltricarboxylate ligand: syntheses, structures, and magnetic properties

Cluster, chain or layer-based 3D Ln-MOFs have been synthesized and they exhibit ferromagnetic or antiferromagnetic interactions. Furthermore, the Dy-MOF shows slow relaxation behavior.

A series of Cd(ii) coordination polymers based on flexible bis(triazole) and multicarboxylate ligands: topological diversity, entanglement and properties

Eight Cd(ii) coordination polymers with diverse topologies based on 1,4-bis(1,2,4-triazol-4-ylmethyl)benzene and multicarboxylate ligands were synthesized and characterized. The 3D topologies of 1, 2 and 3 are unprecedented.

Structural diversity and catalytic properties of five Co2(COO)4cluster-based coordination polymers modified with R-isophthalic acid (R = H, NO2, CH3, OH andtBu)

By regulation the substituents on 5-position of isophthalic acid, we isolated five Co-based CPs with structural diversity, which all constructed from the Co₂(COO)₄unit. The catalytic properties for Knoevenagel condensation and selective epoxidation of styrene have also been investigated.

Ferro- or antiferromagnetic interactions controlled by ditopic or chelating auxiliary ligands in 3D metal-organic frameworks

Three 3D Co(ii) metal-organic frameworks of the general formula [Co(DNNDC)(NN)]_n were reported, where DNNDC = 1,5-dinitronaphthalene-3,7-dicarboxylate and NN = bridging or chelating dipyridyl ligands. The MOFs exhibit similar 3D [Co(DNNDC)]_n frameworks in which double-carboxylate-bridged [Co(OCO)₂]_n chains are cross-linked by naphthalene backbones. The bridging dipyridyl ligands [4,4'-bipyridine (bpy) and 1,2-bis(4-pyridyl)ethane (bpe)] serve as additional linkers between the chains to generate a reinforced framework with new net topology, while the chelating ligand 1,10-phenanthroline (phen) reinforces the frameworks through π-π stacking and C-HO interactions. Remarkably, varying the auxiliary ligand leads to a change in the sign of the magnetic exchange through the double carboxylate bridge: the MOFs with the ditopic bpy and bpe ligands show ferromagnetic interactions, while the one with the chelating phen ligand shows antiferromagnetic exchange. The difference in magnetic exchange is attributable to the subtle change in the coordination conformation of the carboxylate bridge.

Novel manganese(ii) and cobalt(ii) 2D polymers containing alternating chains with mixed azide and carboxylate bridges: crystal structure and magnetic properties

Two new Mn(ii) and Co(ii) complexes based on AABAA alternating chains with mixed azide and carboxylate bridges were synthesized, structurally and magnetically studied.

Solvent-controlled structural diversity observed in three Cu(ii) MOFs with a 2,2′-dinitro-biphenyl-4,4′-dicarboxylate ligand: synthesis, structures and magnetism

Three solvent-dependent 3D Cu^II-based MOFs with diverse topology net have been successfully separated under controllable solvothermal conditions and magnetic studies suggest homo-spin topological ferrimagnetic and antiferromagnetic interactions.

Bis(4-pyridyl)mercury – a new linear tecton in crystal engineering: coordination polymers and co-crystallization processes

Three new coordination polymers have been obtained using bis(4-pyridyl)mercury (py₂Hg) as a spacer: [Cu(Hmea)₂(py₂Hg)](ClO₄)₂·2(py₂Hg) (1), [Cu₂(pa)₂(py₂Hg)(ClO₄)₂]·0.5(py₂Hg)·H₂O (2), and [Cu₂(pa)₂(py₂Hg)₂](BF₄)₂ (3) (Hmea = monoethanolamine; Hpa = propanolamine).

Assembly and Properties of Four New Metal–Organic Complexes Based on 1,4-Naphthalenedicarboxylate: Effect of Four Bis-pyridyl-bis-amide Ligands with Diverse Spacers in the Structures

Four new complexes based on 1,4-naphthalenedicarboxylic acid (1,4-H2NDC) and four bis-pyridyl-bis-amide ligands with various spacers (3-bpye = N,N′-bis(3-pyridinecarboxamide)-1,2-ethane; 3-bpfp = bis(3-pyridylformyl)piperazine; 3-bpcd = N,N′-bis(pyridin-3-yl)cyclohexane-1,4-dicarboxamide; and 3-bpcb = N,N′-bis(3-pyridinecarboxamide)-1,4-benzene), namely [Cu2(1,4-NDC)2(3-bpye)(H2O)] (1), [Cu(1,4-NDC)(3-bpfp)0.5] (2), [Cu3(1,4-NDC)3(3-bpcd)3]·2H2O (3), and [Cu(1,4-NDC)(3-bpcb)] (4), have been hydrothermally synthesized. Complex 1 is a 3D coordination network and represents an 8-connected {420.68} topology. Complex 2 shows a 2-fold interpenetrating 3D architecture with a 6-connected {412.63} topology. Complexes 3 and 4 possess similar 2D sql layers with the {44.62} topology, but the coordination modes of 1,4-NDC ligands and the conformations of the two bis-pyridyl-bis-amide ligands are different. The adjacent layers for 3 and 4 are further linked by hydrogen bonding interactions to form 3D supramolecular networks. The successful assemblies of complexes 1–4 imply that by using the different bis-pyridyl-bis-amide ligands with diverse spacers can produce diverse metal–organic networks. Furthermore, the fluorescence and photocatalytic properties of complexes 1–4 have been investigated.

1D–3D mixed-ligand frameworks with an unusual dmp topology tuned by intersection angles of isomeric benzenedicarboxylates: magnetic properties, gas-dependent calcination-thermolysis and energy storage performances

Three coordination polymers with isomeric ligands were studied and used to prepare CoO and Co₃O₄ particles.

Dimethyl 2-nitrobiphenyl-4,4′-dicarboxylate

The title compound, C16H13NO6, exhibits a biphenyl unit with a dihedral angle between the two aryl rings of 56.01 (5)°. The two ester groups vary slightly from planarity, with aryl–ester dihedral angles of 4.57 (5) and 16.73 (5)°. The nitro group is turned from the aromatic unit with an aryl–nitro dihedral angle of 48.66 (4)°. In the crystal, molecules are connected by weak C—H...O interactions, forming a three-dimensional network.