Two zinc and cadmium coordination polymers constructed with bis(4-(1H-imidazol-1-yl)phenyl)methanone and naphthalene-1,4-dicarboxylate ligands: synthesis and structural characterization

Two coordination polymers, [Zn2(bipmo)2(1,4-nda)2] n (1), {[Cd(bipmo)(1,4-nda)]·(H2O)]} n (2), (bipmo = bis(4-(1H-imidazol-1-yl)phenyl)methanone, H2(1,4-nda) = naphthalene-1,4-dicarboxylic acid), were synthesized under solvothermal conditions. The complexes have been characterized by elemental analyses, IR spectroscopy and single-crystal X-ray diffraction. Complex 1 possesses 3D 2-fold interpenetrating nets with the Schläfli symbol {65·8}. Complex 2 consists a 3D net with the Schläfli symbol {44·610·8}. The luminescent properties of complexes 1 and 2 have been investigated.

Modulating Carbon Dioxide Storage by Facile Synthesis of Nanoporous Pillared-Layered Metal-Organic Framework with Different Synthetic Routes

A Zn(II)-based paddle wheel pillared-layered metal-organic framework, [Zn₂ (DBrTPA)₂(DABCO)].(DMF)₂ (MUT-4), containing 1,4-diazabicyclo[2.2.2]octane (DABCO) and 2,5-dibromoterephthalic acid (DBrTPA) has been successfully synthesized with different synthetic methods, including solvothermal, sonochemical, and their mixing methods, some of which are energy-efficient, rapid, and room-temperature synthetic procedures. Structural characterization of MUT-4 with single-crystal X-ray crystallography showed that it crystallizes in the tetragonal I4₁/acd space group. MUT-4 has shown higher performance than known MOFs in the CO₂ adsorption such as UiO-66, UiO-66-NH₂, UiO-66-NO₂, PCN-66, ZIF-68, UiO-67, bio-MOF-11, MIL-101, MOF-177, ZIF-8, and ZIF-82. It has shown even better CO₂ adsorption performance in comparison to the previously reported DMOFs such as DMOF-1 and other DMOF analogues such as NO₂-DMOF-1, NH₂-DMOF-1, Br-DMOF-1, and Azo-DMOF-1. Furthermore, it has performed even better than modified known MOFs. Also, the carbon dioxide storage capacity of MUT-4 obtained using several different synthetic routes shows a significant difference. Thus, this study exhibited that CO₂ gas adsorption of MUT-4 could be modulated by optimizing its synthetic methods.

Coordination sphere hydrogen bonding as a structural element in metal-organic Frameworks

In the design of new metal-organic frameworks, the constant challenges of framework stability and structural predictability continue to influence ligand choice in favour of well-studied dicarboxylates and similar ligands. However, a small subset of known MOF ligands contains suitable functionality for coordination sphere hydrogen bonding which can provide new opportunities in ligand design. Such interactions may serve to support and rigidity the coordination geometry of mononuclear coordination spheres, as well as providing extra thermodynamic and kinetic stabilisation to meet the challenge of hydrolytic stability in these materials. In this perspective, a collection of pyrazole, amine, amide and carboxylic acid containing species are examined through the lens of (primarily) inner-sphere hydrogen bonding. The influence of these interactions is then related to the overall structure, stability and function of these materials, to provide starting points for harnessing these interactions in future materials design.

A multifunctional benzothiadiazole-based fluorescence sensor for Al3+, Cr3+ and Fe3+

A benzothiadiazole-based Zn^II MOF (JXUST-3) has been synthesized, which is a good multifunctional chemosensor for the detection of Al³⁺, Cr³⁺ and Fe³⁺.

Two topologically different 3D CuII metal-organic frameworks assembled from the same ligands: control of reaction conditions

Bifunctional ligands containing both carboxylic and sulfonate groups can adopt versatile coordination modes to produce novel metal-organic frameworks (MOFs) with high-dimensional networks and interesting topologies. Using 2,2'-disulfonylbiphenyl-4,4'-dicarboxylic acid (H₄L) as a linker and 4,4'-bipyridine (4,4'-bpy) as a co-ligand, two novel 3D Cu^II MOFs, {[Cu₂(L)(4,4'-bpy)_2.5(H₂O)]·1.7H₂O}_n, (1), and {[Cu₂(L)(4,4'-bpy)₂]·DMA·3H₂O}_n, (2), have been synthesized and structurally characterized by X-ray crystallography (DMA is N,N-dimethylacetamide). MOF (1) shows an unprecedented trinodal 4,4,5-connected topology network with the Schläfli symbol (4.6².7³)(4³.6⁵.7.8)(6.7³.8.10), while MOF (2) indicates a binodal 4,6-connected fsc network with the Schläfli symbol (4⁴.6¹⁰.8)(4⁴.6²). MOFs (1) and (2) were further characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction and thermogravimetric analysis. MOF (1) shows a high water and chemical stability. The proton conductivity of (1) and CO₂ adsorption of (2) were also investigated.

Isomerism in double-pillared-layer coordination polymers - structures and photoreactivity

The existence of isomerism in coordination polymeric structures offers opportunities to understand structure-function relationships. Herein the serendipitous isolation is reported of two isomeric double-pillared-layer coordination polymeric structures arising from two different types of carboxyl-ate bonding of benzene-1,4-di-carboxyl-ate ligands to zinc(II), which constitutes a new type of structural isomerism. The different bonding modes not only alter the shape and size of the pores, but also the nature of interpenetration and photoreactivity. Although two trans,cis,trans-bpeb ligands with conjugated olefin bonds are aligned in close proximity in both of the structures, one isomer undergoes a double [2 + 2] cyclo-addition reaction and the second isomer only offers an incomplete single cyclo-addition product. This work demonstrates how small changes in the structural connectivity can have an impact on the overall structural, physical and chemical properties of such materials.

Interpenetrated Double Pillared-Layer CoII MOFs with pcu Topology

Three double pillared-layer CoII metal–organic frameworks (MOFs) with a pcu topology of a long, conformationally flexible, dipyridyl spacer ligand, 1,4-bis[2-(4-pyridyl)ethenyl]benzene (bpeb), and aromatic dicarboxylates (1,4-benzenedicarboxylate (bdc), 2,6-naphthalenedicarboxylate (ndc), and biphenyl-4,4′-dicarboxylate (bpdc)) have been synthesised and structurally characterised by X-ray crystallography. The MOFs are denoted as [Co2(bpeb)2(bdc)2]·DMF·3H2O (1), [Co2(bpeb)2(ndc)2]·1.75DMF·3.75H2O (2), and [Co2(bpeb)2(bpdc)2]·3.5DMF·4H2O (3). In the dinuclear repeating unit, four carboxylates are bonded to two CoII atoms forming a (4,4) layer structure. The axial positions are occupied by bpeb ligands. Of these, 1 and 2 have 2-fold interpenetration, whereas 3 displays 3-fold interpenetration. The two bpeb space ligands in 1 have trans,trans,trans and trans,cis,trans conformations. In contrast, the bpeb ligands in 2 and 3 have a trans,cis,trans conformation. Although the olefin groups in two adjacent bpeb ligands, as the double pillars in 2 and 3, satisfy the conditions for photo-dimerisation to occur, they are photo-inactive. The conformational changes of bpeb, bonding modes of the dicarboxylates, and pore sizes in these double pillared-layer compounds have been discussed.

Recent advances on supramolecular isomerism in metal organic frameworks

This review highlights selected examples of supramolecular isomerism in the area of metal organic frameworks and major factors of their formation are also discussed.

Probing the competition between acetate and 2,2′-bipyridine ligands to bind to d-block group 12 metals

Molecular and structural diversity in Zn²⁺, Cd²⁺ and Hg²⁺ complexes towards high-efficiency luminescent materials.

Influence of N-heteroaromatic π–π stacking on supramolecular assembly and coordination geometry; effect of a single-atom change in the ligand

A study on how the polarization of aromatic systems, through the introduction of a nitrogen heteroatom, affects the π–π interactions and crystal packing of mercury coordination compounds.

A series of coordination polymers based on varied polycarboxylates and different imidazole-containing ligands: syntheses, crystal structures and physical properties

To investigate the effect of organic ligands on the coordination frameworks, seven nickel(ii) coordination polymers, based on varied polycarboxylates and different imidazole-containing ligands, are synthesized under hydrothermal method.

Self-triggered conformations of disulfide ensembles in coordination polymers with multiple metal clusters

Five coordination polymers containing manganese(ii) ions, 6,6′-dithiodinicotinate, and/or N-donor coligands display mononuclear, trinuclear cluster and polymeric metal oxide wire and exhibit intrinsic biomimetic characteristics.

Tunable photoluminescence and direct white-light emission in Mg-based coordination networks

The bpy, dpe and dppe were introduced, respectively, to construct Mg-NDC CPs exhibiting tunable photoluminescence and even direct white-light emission.

Structural versatility and luminescent properties in d(10) metal ion polymers with 1,4-naphthalenedicarboxylate acid and 4,4'-dipyridyl N,N'-dioxide

Hydrothermal reactions of d(10) metal ions (Cd(2+) and Zn(2+)) with 1,4-naphthalenedicarboxylate acid (1,4-H2NDC) and 4,4'-dipyridyl N,N'-dioxide (4,4'-dpdo) form two three-dimensional grid-like coordination polymers [Cd2(1,4-NDC)2(4,4'-dpdo)]·H2O 1 and [Zn4(μ3-OH)2(1,4-NDC)3(H2O)2](4,4'-dpdo)·2H2O 2. Both coordination polymers were characterized by single crystal X-ray diffraction, IR spectroscopy, XRPD, thermogravimetric and elemental analyses. Polymer 1 exhibits rare alternating arranged 1,4-NDC(2)(-) and 4,4'-dpdo spacers between adjacent 1D zigzag chains containing Cd-octahedral coordination geometries. Polymer 2 is constructed from infrequent chair-like [Zn4(μ3-OH)2](6+) inorganic SBUs with four- and six-coordination geometries and only 1,4-NDC(2)(-) as "single-bridge" and "double-bridges" to form a 3D framework. Both polymers give strong luminescent emissions in the solid state at room temperature.

Solvothermal synthesis, crystal structure and photoluminescence properties of four Cd(ii) coordination polymers with different topological structures

Four coordination polymers assembled by tetrabromoterephthalic acid and various bis(imidazole) ligands: synthesis, topological structures and luminescence properties.

A series of metal–organic frameworks containing diverse secondary building units derived from a flexible triazine-based tetracarboxylic ligand

Five new coordination polymers containing diverse SBUs derived from a flexible triazine-based tetracarboxylic acid have been solvothermally synthesized and characterized.

An unusual cobalt(ii)-based single-walled metal–organic nanotube

Self-adaption to the formation of an unusual cobalt(ii)-based single-walled metal–organic nanotube is reported. In addition, a pseudo-merohedral twinning problem encountered in the X-ray diffraction analysis was solved, which significantly improves the crystallographic results.