Topological Analysis of Metal–Organic Frameworks with Polytopic Linkers and/or Multiple Building Units and the Minimal Transitivity Principle

A highly robust metal–organic framework based on an aromatic 12-carboxyl ligand with highly selective adsorption of CO2 over CH4

A stable microporous anionic MOF based on a dendritic aromatic 12-carboxyl ligand was synthesized, which demonstrates high Q_st for CO₂ and highly selective gas adsorption of CO₂ over CH₄.

Turn-on luminescence based discrimination of protic acids using a flexible layered metal–organic coordination polymer

A flexible layered metal–organic coordination polymer used as probe for turn-on luminescence based discrimination of protic acids and amino acids.

Sc2(pydc)2 unit based 1D, 2D and 3D metal–organic frameworks as heterogeneous Lewis acid catalysts for cyanosilylation

Three new Sc-MOFs have been synthesized using H₂pydc linker and Sc(iii) ions. 1 features a ladder-shaped chain, 2 displays a waved layer and 3 exhibits a (3,3)-connected nbo-a network. All three compounds exhibit good catalytic abilities for the cyanosilylation of aldehyde.

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.

Isoreticular isomerism in 4,4-connected paddle-wheel metal–organic frameworks: structural prediction by the reverse topological approach

By screening the possible range of isoreticular isomers, the structure of copper paddle-wheel-based metal–organic frameworks with nbo-b topology can be predicted and the formation of different phases can be rationalized.

Visible detection of explosive nitroaromatics facilitated by a large stokes shift of luminescence using europium and terbium doped yttrium based MOFs

Two lanthanide doped highly luminescent MOFs have been synthesized and characterized. The MOFs are highly efficient for the detection of trace amount of explosive nitroaromatics by visible colour change.

Positional isomeric effect on the structural variation of Cd(ii) coordination polymers based on flexible linear/V-shaped bipyridyl benzene ligands

Solvothermal reactions of Cd(OAc)₂·2H₂O with 2,2′-azodibenzoic acid and five positional isomeric N-donor bipyridyl benzene ligands in MeOH/H₂O at 170 °C gave rise to five coordination polymers. Complexes 1–5 were characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction.

A series of mixed-ligand 2D and 3D coordination polymers assembled from a novel multifunctional pyridine-tricarboxylate building block: hydrothermal syntheses, structural and topological diversity, and magnetic and luminescent properties

4-(5-Carboxypyridin-2-yl)isophthalic acid (H₃L) was applied as a new principal building block for the self-assembly generation of mixed-ligand coordination polymers.

Synthesis, structures and magnetic properties in 3d-electron-rich isostructural complexes based on chains with sole syn–anti carboxylate bridges

A series of isostructures based on 2,2′,4,4′-biphenyltetracarboxylic acid have been synthesized via solvothermal reaction, whereas magnetic studies reveal the polymers with sole syn–anti carboxylate bridges show different magnetic behaviors of uniform chains.

Pentagonal helices in a periodic metal–organic framework. Crystals as computers for discovering structures of minimal transitivity

A net of exceptional complexity is found in the structure of a metal–organic framework with pentagonal structure-building units.

Using halogen⋯halogen interactions or C/N–H⋯Cl hydrogen bonding to direct crystal packing in tetrachlorophthalic acid with N-heterocyclic compounds

Hydrogen bonding patterns and halogen⋯halogen interactions, C/N–H⋯Cl hydrogen bonding in a series of multi-component molecular structures constructed by tetrachlorophthalic acid with N-heterocycles were discussed.

Syntheses, structures, and properties of six cobalt(ii) complexes based on a tripodal tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine ligand

Six new cobalt(ii) metal–organic frameworks based on the tripodal tris(4-(1H-1,2,4-triazol-1-yl)phenyl)amine (TTPA) ligand with different aromatic carboxylate auxiliary ligands have been synthesized and structurally characterized in detail. All the complexes show optical semiconductive properties.

One- and two-dimensional Cd(II) coordination polymers incorporating organophosphinate ligands

Reaction of cadmium nitrate with diphenylphosphinic acid in dimethylformamide solvent yielded the one-dimensional coordination polymer catena-poly[[bis(dimethylformamide-κO)cadmium(II)]-bis(μ-diphenylphosphinato-κ(2)O:O')], [Cd(C12H10O2P)2(C3H7NO)2]n, (I). Addition of 4,4'-bipyridine to the synthesis afforded a two-dimensional extended structure, poly[[(μ-4,4'-bipyridine-κ(2)N:N')bis(μ-diphenylphosphinato-κ(2)O:O')cadmium(II)] dimethylformamide monosolvate], {[Cd(C12H10O2P)2(C10H8N2)]·C3H7NO}n, (II). In (II), the 4,4'-bipyridine molecules link the Cd(II) centers in the crystallographic a direction, while the phosphinate ligands link the Cd(II) centers in the crystallographic b direction to complete a two-dimensional sheet structure. Consideration of additional π-π interactions of the phenyl rings in (II) produces a three-dimensional structure with channels that encapsulate dimethylformamide molecules as solvent of crystallization. Both compounds were characterized by single-crystal X-ray diffraction and FT-IR analysis.

Zeolite-like metal-organic frameworks (ZMOFs): design, synthesis, and properties

This review highlights various design and synthesis approaches toward the construction of ZMOFs, which are metal-organic frameworks (MOFs) with topologies and, in some cases, features akin to traditional inorganic zeolites. The interest in this unique subset of MOFs is correlated with their exceptional characteristics arising from the periodic pore systems and distinctive cage-like cavities, in conjunction with modular intra- and/or extra-framework components, which ultimately allow for tailoring of the pore size, pore shape, and/or properties towards specific applications.

Increasing the Stability of Metal-Organic Frameworks

Metal-organic frameworks (MOFs) are a new category of advanced porous materials undergoing study by many researchers for their vast variety of both novel structures and potentially useful properties arising from them. Their high porosities, tunable structures, and convenient process of introducing both customizable functional groups and unsaturated metal centers have afforded excellent gas sorption and separation ability, catalytic activity, luminescent properties, and more. However, the robustness and reactivity of a given framework are largely dependent on its metal-ligand interactions, where the metal-containing clusters are often vulnerable to ligand substitution by water or other nucleophiles, meaning that the frameworks may collapse upon exposure even to moist air. Other frameworks may collapse upon thermal or vacuum treatment or simply over time. This instability limits the practical uses of many MOFs. In order to further enhance the stability of the framework, many different approaches, such as the utilization of high-valence metal ions or nitrogen-donor ligands, were recently investigated. This review details the efforts of both our research group and others to synthesize MOFs possessing drastically increased chemical and thermal stability, in addition to exemplary performance for catalysis, gas sorption, and separation.

A three-dimensional zinc-based coordination polymer built from 5-carboxylato-1-carboxylatomethyl-2-oxidopyridinium with a 4-connected sra topology

A novel three-dimensional Zn(II) complex, poly[aqua(μ4-5-carboxylato-1-carboxylatomethyl-2-oxidopyridinium)zinc(II)], [Zn(C8H5NO4)(H2O)]n, has been prepared by hydrothermal assembly of Zn(CH3COO)2·2H2O and 5-carboxy-1-(carboxymethyl)pyridin-1-ium-2-olate (H2ccop). The ccop(2-) anions bridge the Zn(II) cations in a head-to-tail fashion via monodentate aromatic carboxylate and phenolate O atoms to form an extended zigzag chain which runs parallel to the [011] direction. One O atom of the aliphatic carboxylate group of the ccop(2-) ligand coordinates to the Zn(II) atom of a neighbouring chain thereby producing undulating layers which lie parallel to the (01-1) plane. A similar parallel undulating planar structure can be obtained if a path involving the other O atom of the aliphatic carboxylate group is considered. Thus, the aliphatic carboxylate group acts in a bridging bidentate mode to give extended -Zn-O-C-O-Zn- sequences running parallel to [001] which link the layers into an overall three-dimensional framework. The three-dimensional framework can be simplified as a 4-connected sra topology with a Schläfli symbol of 4(2).6(3).8 if all the Zn(II) centres and ccop(2-) anions are regarded as tetrahedral 4-connected nodes. The three-dimensional luminescence spectrum was measured at room temperature with excitation and emission wavelengths of 344-354 and 360-630 nm, respectively, at intervals of 0.15 and 2 nm, respectively.

3-(4-Pyridyl)-acetylacetone – a fully featured substituted pyridine and a flexible linker for complex materials

3-(4-Pyridyl)-acetylacetone (HacacPy) acts as a pyridine-type ligand towards CdX2(X= Cl, Br, I). Chain polymers with six-coordinated metal cations are obtained from CdCl2and with alternating five- and six-coordinated Cd centers from CdBr2. In either case, the formation of these compounds does not depend on the precise stoichiometry. In contrast, two different reaction products form with the heavier congener CdI2, namely a ligand-rich molecular complex CdI2(HacacPy)2and a ligand-deficient one-dimensional polymer [CdI2(HacacPy)]1∞. Interconversion between these two iodo derivatives is possibleviathermal degradation and mechanochemical synthesis. The acetylacetone moiety in HacacPy may be deprotonated and chelated to FeIII, and the resulting complex Fe(acacPy)3reacts analogously to a bridging polypyridine ligand towards the same Cd halides as the molecule HacacPy itself. With CdCl2and CdBr2, isomorphous chain polymers are obtained in which the Cd cations adopt distorted octahedral coordination and one of the peripheric pyridyl groups remains uncoordinated. With CdI2, the iron complex acts as a \mu _{{3}}-Fe(acacPy)3bridge between tetrahedral Cd centers and gives rise to a ladder structure.