Novel Co5 and Ni4 Metal Complexes and Ferromagnets by the Combination of 2-Pyridyl Oximes with Polycarboxylic Ligands

The use of 2-pyridyl oximes in metal complexes chemistry has been extensively investigated in the last few decades as a fruitful source of species with interesting magnetic properties. In this work, the initial combination of pyridine-2-amidoxime (pyaoxH₂) and 2-methyl pyridyl ketoxime (mpkoH) with isonicotinic acid (HINA) and 3,5-pyrazole dicarboxylic acid (H₃pdc) has provided access to three new compounds, [Ni₄(INA)₂(pyaox)₂(pyaoxH)₂(DMF)₂] (1), [Co₅(mpko)₆(mpkoH)₂(OMe)₂(H₂O)](ClO₄)₆ (2), and [Co₅(OH)(Hpdc)₅(H₂pdc)] (3). 1 displays a square-planar metal topology, being the first example that bears simultaneously HINA and pyaoxH₂ in their neutral or ionic form. The neighbouring Ni₄ units in 1 are held together through strong intermolecular hydrogen bonding interactions, forming a three-dimensional supramolecular framework. 2 and 3 are mixed-valent Co₄^IIICo^II and Co₂^IIICo^II₃ compounds with a bowtie and trigonal bipyramidal metal topology, accordingly. Direct current and alternate current magnetic susceptibility studies revealed that the exchange interactions between the Ni^II ions in 1 are ferromagnetic (J = 1.79(4) cm⁻¹), while 2 exhibits weak AC signals in the presence of a magnetic field. The syntheses, crystal structures, and magnetic properties of 1–3 are discussed in detail.

Crystal structure of bis{tetraaqua-[μ3-1-(4-carboxylatophenyl)-5-methyl-1H-pyrazole-3-carboxylate-κ4 N,O,O′,O″] [μ2-1-methyl-1H-pyrazole-3,5-dicarboxylate-κ3 N,O:O]dicobalt(II)} dihydrate, C36H44Co4N8O26

C36H44Co4N8O26, triclinic, P 1 ‾ $‾{1}$ (no. 2), a = 6.6434(4) Å, b = 9.3788(5) Å, c = 18.5581(10) Å, α = 86.262(2)°, β = 89.642(2)°, γ = 84.726(2)°, V = 1148.96(11) Å3, Z = 1, Rgt (F) = 0.0258, ωRref (F 2) = 0.0679, T = 298(2) K.

CCDC no.: 1917980

A series of 3D lanthanide coordination polymers decorated with a rigid 3,5-pyridinedicarboxylic acid linker: syntheses, structural diversity, DFT study, Hirshfeld surface analysis, luminescence and magnetic properties

Single crystal X-ray diffraction studies reveal the formation of six new coordination polymers (CPs) with the general formulas [Dy(3,5-pdc)(3,5-pdcH)(H2O)2]n·nH2O (1), [Pr2(3,5-pdc)3(H2O)2]n·2n(H2O) (2), [Sm2(3,5-pdc)3(H2O)3]n·nH2O (3), {[Eu2(3,5-pdc)3(H2O)3(CH3CHO)]n·n[2(H2O)(DMF)]} (4), {[Gd2(3,5-pdc)3 (H2O)2]n·2nH2O} (5) and [Er(3,5-pdc)(adip)0.5(H2O)]n (6) (where 3,5-pdc2- = fully deprotonated; 3,5-pdcH- = partially deprotonated 3,5-pyridinedicarboxylic acid; adip2- = fully deprotonated adipic acid; and DMF = dimethylformamide) by solvothermal self-assembly of lanthanide ions with rigid 3,5-pyridinedicarboxylic acid as a linker and adipic acid as an auxiliary flexible spacer (only coordinated in CP 6). CPs 1 and 2 crystallize in the triclinic P1[combining macron] space group, whereas CPs 3, 4 and 6 crystallize in the monoclinic P21/n, P21/c and C2/c space groups, respectively. CP 5 exhibits the trigonal R3 space group. The 3,5-pdc ligand exhibits eight diverse coordination modes in CPs 1-6, whereas the adipic acid spacer in CP 6 shows only one coordination mode (μ4-κO:κO,O:κO:κO,O). The organic ligands interconnect with metal ions to generate 3D metal-organic frameworks with a variety of intriguing topologies. Theoretical studies, DFT calculations and Hirshfeld surface analysis support the structures adopted by the various CPs. CPs 3 (Sm) and 4 (Eu) emit strong ligand-sensitized characteristic f-f luminescence. Weak ferromagnetic interactions have been studied at low temperatures for CP 1 and CP 5.

Novel dirhodium coordination polymers: the impact of side chains on cyclopropanation

Seven novel dirhodium coordination polymers (Rh₂–Ln) (n = 1–7) are prepared by employing bitopic ligands to connect dirhodium nodes.

Water-stable Eu-MOF fluorescent sensors for trivalent metal ions and nitrobenzene

We have synthesized two functionalized Eu-MOFs and found that the MOFs are promising luminescent probes for selectively sensing metal ions (Fe³⁺and Cr³⁺) and nitrobenzene.

Mesoxalate as Cu(ii)–Ln(iii) linker in the construction of MOFs in DMSO/water medium

The combination of [Cu₃(Hmesox)₃]³⁻ with La(iii), Ce(iii), Pr(iii), Nd(iii) and Eu(iii) in DMSO/H₂O yields 3d–4f heterometallic metal–organic frameworks, with the dimensionality of the network being controlled by the coordination number of the Ln(iii) ion.

Ionothermal synthesis, crystal structure, topology and catalytic properties of heterometallic coordination polymers constructed from N-(phosphonomethyl) iminodiacetic acid

Four FeLn heterometallic coordination polymers with the H₄pmida ligand were ionothermally synthesized and characterized. Their catalytic properties in the Knöevenagel condensation reaction were investigated.

Two dimensional porous 3d–4f heterometallic coordination polymers constructed by pyridine-2,3-dicarboxylic acid

Four porous Co^IIILn^III 3d–4f heterometallic coordination polymers constructed by the pydcH₂ ligand were hydrothermally synthesized and characterized. The adsorption and catalytic properties of compound Co^IIIDy^III were investigated.