Hydrothermal Assembly, Structural Multiplicity, and Catalytic Knoevenagel Condensation Reaction of a Series of Coordination Polymers Based on a Pyridine-Tricarboxylic Acid

A pyridine-tricarboxylic acid, 5-(3',5'-dicarboxylphenyl)nicotinic acid (H3dpna), was employed as a adjustable block to assemble a series of coordination polymers under hydrothermal conditions. The seven new coordination polymers were formulated as [Co(μ3-Hdpna)(μ-dpey)]n·nH2O (1), [Zn4.5(μ6-dpna)3(phen)3]n (2), [Co1.5(μ6-dpna)(2,2'-bipy)]n (3), [Zn1.5(μ6-dpna)(2,2'-bipy)]n (4), [Co3(μ3-dpna)2(4,4'-bipy)2(H2O)8]n·2nH2O (5),[Co(bpb)2(H2O)4]n[Co2(μ3-dpna)2(H2O)4]n·3nH2O (6), and [Mn1.5(μ6-dpna)(μ-dpea)]n (7), wherein 1,2-di(4-pyridyl)ethylene (dpey), 1,10-phenanthroline (phen), 2,2'-bipyridine(2,2'-bipy),4,4'-bipyridine(4,4'-bipy),1,4-bis(pyrid-4-yl)benzene (bpb), and 1,2-di(4-pyridyl)ethane (dpea) were employed as auxiliary ligands. The structural variation of polymers 1-7 spans the range from a 2D sheet (1-4, 6, and 7) to a 3D metal-organic framework (MOF, 5). Polymers 1-7 were investigated as heterogeneous catalysts in the Knoevenagel condensation reaction, leading to high condensation product yields (up to 100%) under optimized conditions. Various reaction conditions, substrate scope, and catalyst recycling were also researched. This work broadens the application of H3dpna as a versatile tricarboxylate block for the fabrication of functional coordination polymers.

1D ladder and 2D bilayer coordination polymers constructed from a new T-shaped ligand: luminescence, magnetic and CO2 gas adsorption properties

1D ladder and 2D bilayer coordination polymers are constructed by using a new T-shaped ligand, in which the 2D bilayer exhibits CO₂ gas adsorption features.

Influence of different metal ions on the assembly, structures, and properties of two complexes based on the semi-rigid bis(pyridyl)-bis(amide) ligand and 4,4′-oxybis(benzoic acid)

Two transitional metal complexes, [Zn(oba)(3-bpcd)] n (1) and [Cd(oba)(3-bpcd)0.5] n (2) [H2oba= 4,4′-oxybis(benzoic acid), 3-bpcd=N,N′-bis(pyridin-3-yl)cyclohexane-1,4-dicarboxamide], have been hydrothermally synthesized and structurally characterized by elemental analyses, infrared spectra, powder X-ray diffraction, thermogravimetric and single-crystal X-ray diffraction. Complex 1 possesses a three-fold interpenetrating network based on layers with a 4-connected sql topology. Complex 2 is a layered framework constructed by the oba anions and 3-bpcd ligands, which represents a binodal (3,4)-connected {62.10}{6} topology. The adjacent layers of complex 2 are further linked by hydrogen bonding interactions to build a three-dimensional supramolecular architecture. The differences of metal ions in coordination modes show a significant effect on the final structures of the Zn(II)/Cd(II) complexes. The photocatalytic activities and the fluorescence sensing properties of complexes 1 and 2 were investigated.

Four 3D coordination polymers based on layers with single syn-anti carboxylate bridges: synthesis, structures, and magnetic properties

Four novel coordination polymers (CPs) based on a new 4-(3,5-dicarboxylphenyl) picolinic acid ligands (H3L), [M3(L)2(H2O)6]·4H2O (M3 = Mn3, 1; Co3, 2; Ni3, 3, Co1.01Ni1.99, 4), have been hydrothermally synthesized, and structurally and magnetically characterized. In these isomorphous CPs, octahedrally coordinated metal ions are linked by the single syn-anti carboxylate bridge (μ-COO) to give linear trinuclear motifs. The motifs are connected through the other single syn-anti carboxylate bridge (μ-COO) to give a 2D (4,4) layer, and the layers are interlinked by the L ligands into 3D frameworks. Magnetic measurement indicates that antiferromagnetic interactions between metal ions are mediated through the single syn-anti carboxylate bridges in 1 and 2, while the same carboxylate bridges in 3 transmit ferromagnetic couplings. The bimetallic CP 4 shows interesting complicated magnetic behaviors due to the competition effect of Co(ii) and Ni(ii) ions.

Two metal–organic frameworks based on pyridyl–tricarboxylate ligands as size-selective catalysts for solvent-free cyanosilylation reaction

Two novel 3D metal–organic frameworks based on multifunctional pyridyl–tricarboxylate ligands as size-selective heterogeneous catalysts for the cyanosilylation of acetaldehydes.