Hydrothermal assembly, structures, topologies, luminescence, and magnetism of a novel series of coordination polymers driven by a trifunctional nicotinic acid building block

In this work, a trifunctional N,O-building block, 5-(4-carboxyphenoxy)nicotinic acid (H₂cpna), that combines three distinct types of functional groups (COOH, N-pyridyl, and O-ether) was used for the hydrothermal assembly of thirteen new coordination compounds: [Co(μ₃-Hcpna)₂]_n (1), [Mn(μ₄-cpna)(H₂O)]_n (2), [Mn(μ₄-cpna)(H₂O)₂]_n (3), [Mn(μ-cpna)(2,2'-bipy)(H₂O)₂]_n (4), {[Ni(μ₃-cpna)(2,2'-bipy)(H₂O)]₂·H₂O}_n (5), {[Cd(μ₃-cpna)(2,2'-bipy)]·2H₂O}_n (6), [Zn₂(μ-cpna)₂(2,2'-bipy)₂] (7), [Cu(μ-cpna)(2,2'-bipy)(H₂O)]_n (8), {[Mn(μ-cpna)(phen)₂]·6H₂O}_n (9), {[Ni(μ₃-cpna)(phen)(H₂O)]·H₂O}_n (10), [Zn₂(μ-cpna)₂(phen)₂] (11), {[Pb(μ₃-cpna)(phen)]·H₂O}_n (12), and [Ni(μ₃-cpna)(4,4'-bipy)_0.5(H₂O)]_n (13). These products were synthesized from the corresponding metal(ii) chlorides, H₂cpna, NaOH, and optional N-donor supporting ligands or templates {bis(4-pyridyl)amine (bpa), 2,2'-bipyridine (2,2'-bipy), 4,4'-bipyridine (4,4'-bipy), or 1,10-phenanthroline (phen)}. Products 1-13 were characterized in the solid state by standard methods, including elemental and thermogravimetric analysis (TGA), IR spectroscopy, and powder (PXRD) and single-crystal X-ray diffraction. The structures of 1-13 feature distinct structural types, namely the 3D metal-organic frameworks (MOFs 1-3), the 2D coordination polymers (5, 6, 10, 12, and 13), the 1D coordination polymers (4, 8, and 9), and the 0D discrete cyclic dimers (7 and 11). Such a wide structural diversity of 1-13 is driven by various factors, including the type of the metal(ii) node, the deprotonation degree of H₂cpna, and/or the type of supporting ligand or template. Notably, an addition of bpa can tune the structure of MOF 3 by the template effect. Topological classification of underlying metal-organic networks was performed, leading to several distinct topological nets: rtl (in 1), hxg-d-4-C2/m (in 2), sra (in 3), 2C1 (in 4, 8 and 9), fes (in 5, 10, and 12), hcb (in 6), and 3,4L83 (in 13). The magnetic behavior of 1-5, 8-10, and 13 was studied and theoretically modeled, disclosing antiferromagnetic interactions. The luminescence behavior of 6, 7, 11, and 12 was also investigated.

Five transition metal coordination polymers driven by a semirigid trifunctional nicotinic acid ligand: selective adsorption and magnetic properties

Five coordination polymers have been synthesized by a new organic linker containing three distinct types of functional groups together with the mixed 2,2′-bipy or 4,4′-bipy co-ligand, revealing various framework structures and selective gas adsorption and magnetic properties.

Bringing 5-(3,4-dicarboxylphenyl)picolinic acid to crystal engineering research: hydrothermal assembly, structural features, and photocatalytic activity of Mn, Ni, Cu, and Zn coordination polymers

A novel tricarboxylic acid block with phthalate and picolinate functionalities was applied for the assembly of a new series of coordination polymers with interesting structural features and functional properties.

A 3D supramolecular architecture based on 2,2′-oxybis(benzoic acid) and trans-1,2-bis(4-pyridyl)ethylene as ligands for Co(II)

The reaction of CoCl2·6H2O with mixed ligands of 2,2′-oxybis(benzoic acid) (2,2′-H2oba) and trans-1,2-bis(4-pyridyl)ethylene (bpe) under hydrothermal conditions produced a new 3D cobalt(II) supramolecular architecture {[Co(oba)(bpe)(H2O)]·1/2bpe} n (1), which was structurally characterized by elemental analysis, infrared spectroscopy, thermogravimetric analyses, and single-crystal X-ray diffraction. The results show that the Co(II) ions are connected to form an infinite polymeric chain by bpe ligands in complex 1. Due to strong intermolecular O–H···O hydrogen bonds, the adjacent chains are connected to generate a double-chain structure. These double chains are joined by O–H···N hydrogen bonding to produce a 2D supramolecular architecture. Furthermore, through intermolecular C–H···O hydrogen bonds, the layers are linked into a 3D supramolecular structure. Magnetic susceptibility measurements have indicated that complex 1 shows weak antiferromagnetic interactions between adjacent Co(II) ions.

Two Isostructural Metal-Organic Frameworks Directed by the Different Center Metal Ions, Exhibiting the Ferrimagnetic Behavior and Slow Magnetic Relaxation

Two 3D isostructural metal-organic frameworks with 1D ferrimagnetic chains, formulated as [M3(L)(μ3-OH)2(H2O)4] [H4L = (1,1':4',1″-terphenyl)-2',3,3″,5'-tetracarboxylic acid, where M = Mn for 1 and Co for 2], have been successfully synthesized by employing different center metal ions and a multicarboxylate ligand under identical reaction conditions in this work. The single-crystal X-ray diffraction data of 1 and 2 reveal that the complexes are two 3D isostructural frameworks based on 1D [M3(OH)2]n chains composed of triangular subunits as rod-shaped secondary building units, which are classified as binodal 4,6-connected fry nets with the point symbol (5(10)·6(3)·7(8))(5(4)·6(2)). The magnetic properties revealed that complexes 1 and 2 exhibit ferrimagnetic behavior. Also, the alternating-current susceptibility of 2 displays slow magnetic relaxation, showing interesting magnetic behavior of a single-chain magnet with an effective energy barrier of 32 K.

Syntheses, structures, and magnetic properties of three new cyano-bridged heterobimetallic chains based on [Fe(Tp*)(CN)3]−

Three, new, one-dimensional (1D) heterobimetallic cyano-bridged chain complexes of squares were prepared. The simultaneous presence of magnetic and porous properties have been found in compound 1–3.

Four new lanthanide–organic frameworks: selective luminescent sensing and magnetic properties

Four new isostructural lanthanide–organic frameworks have been synthesized, which show 2D layer-by-layer structures, and exhibit highly selective and efficient luminescence sensing for Fe³⁺ and Cr⁶⁺ ions in aqueous solution.

4-(4-Carboxyphenoxy)phthalate-based coordination polymers and their application in sensing nitrobenzene

Structural characterization of 4-(4-carboxyphenoxy)phthalate-based Cd²⁺ and Mn²⁺ coordination polymers are reported, and Cd²⁺ coordination polymer can serve as probe to sense nitrobenzene.

Quasi-1D physics in metal-organic frameworks: MIL-47(V) from first principles

The geometric and electronic structure of the MIL-47(V) metal-organic framework (MOF) is investigated by using ab initio density functional theory (DFT) calculations. Special focus is placed on the relation between the spin configuration and the properties of the MOF. The ground state is found to be antiferromagnetic, with an equilibrium volume of 1554.70 Å(3). The transition pressure of the pressure-induced large-pore-to-narrow-pore phase transition is calculated to be 82 MPa and 124 MPa for systems with ferromagnetic and antiferromagnetic chains, respectively. For a mixed system, the transition pressure is found to be a weighted average of the ferromagnetic and antiferromagnetic transition pressures. Mapping DFT energies onto a simple-spin Hamiltonian shows both the intra- and inter-chain coupling to be antiferromagnetic, with the latter coupling constant being two orders of magnitude smaller than the former, suggesting the MIL-47(V) to present quasi-1D behavior. The electronic structure of the different spin configurations is investigated and it shows that the band gap position varies strongly with the spin configuration. The valence and conduction bands show a clear V d-character. In addition, these bands are flat in directions orthogonal to VO6 chains, while showing dispersion along the the direction of the VO6 chains, similar as for other quasi-1D materials.