Ternary Nets formed by Self-Assembly of Triangles, Squares, and Tetrahedra

Facile isolation of a stable S6-symmetric methanol hexamer using the guest-free microporous metal-organic framework: zinc 5-tert-butyl isophthalate

The ordered structure of the guest-free microporous metal-organic framework zinc 5-tert-butyl isophthalate {Zn[(CH3)3CC6H3(CO2)2]} has been determined and shown to be easily loaded with methanol to form {Zn[(CH3)3CC6H3(CO2)2]}·CH3OH. The methanol forms a S6-symmetric hexamer within the pores of the material that is uniquely defined by the void space and exerts a subtle structural effect on the framework structure of the host. The work demonstrates the use of this type of metal-organic framework as a matrix to isolate unique molecular clusters in a facile manner.

Mapping the Assembly of Metal-Organic Cages into Complex Coordination Networks

Structural transformations of supramolecular assemblies play an important role in the synthesis of complex metal-organic materials. Nonetheless, often little is known of the assembly pathways that lead to the final product. This work describes the conversion of cubic metal-organic polyhedra to connected-cage networks of varying topologies. The neutral cubic cage assembly of formula {Pd₃ [PO(NiPr)₃ ]}₈ (PZDC)₁₂ has been synthesized from {Pd₃ [(NiPr)₃ PO](OAc)₂ (OH)}₂ ⋅2 (CH₃ )₂ SO and 2,5-pyrazenedicarboxilic acid (PZDC-2H). This 42-component self-assembly is the largest known among the neutral cages with Pd^II ions. The cage contains twenty-four vacant carboxylate O-sites at the PZDC ligands that are available for further coordination. Post-assembly reactions of the cubic cage with Fe^II and Zn^II ions produced cage-connected networks of dia and qtz topologies, respectively. During these reactions, the discrete cubic cage transforms into a network of tetrahedral cages that are bridged by the 3D metal ions. The robustness of the [Pd₃ {[PO(NiPr)₃ }]³⁺ molecular building units made it possible to map the post-assembly reactions in detail, which revealed a variety of intermediate 1D and 2D cage networks. Such step-by-step mapping of the transformation of discrete cages to cage-connected frameworks is unprecedented in the chemistry of coordination driven assemblies.

Crystal structure of tetrakis(μ 2-3,3-dimethylacrylato-κ 2 O,O′)-bis(2-aminopyrimidine-κN) dicopper(II), C28H38Cu2N6O8

C28H38Cu2N6O8, monoclinic, P21/c (no. 14), a = 10.6191(1) Å, b = 14.6736(2) Å, c = 11.6519(2) Å, β = 111.056(1)°, V = 1694.38(4) Å3, Z = 2, R gt(F) = 0.0298, wR ref(F 2) = 0.0871, T = 296 K.

Crystal structure of a chloride-bridged copper(II) dimer: piperazine-1,4-dium bis-(di-μ-chlorido-bis[(4-carboxypyridine-2-carboxyl-ato-κ2N,O2)chlorido-cuprate(II)]

Crystals of a new dimeric chloride-bridged cuprate(II) derived from pyridine-2,4-di-carb-oxy-lic acid were obtained solvothermally in the presence of piperazine and hydro-chloric acid. The crystal structure determination of the title salt, (C4H12N2)[Cu2(C7H4NO4)2Cl4], revealed one of the carboxyl groups of the original pyridine-2,4-di-carb-oxy-lic acid ligand to be protonated, whereas the other is deprotonated and binds together with the pyridine N atom to the CuII atom. The coordination environment of the CuII atom is distorted square-pyramidal. One of the chloride ligands bridges two metal cations to form a centrosymmetric dimer with two different Cu-Cl distances of 2.2632 (8) and 2.7853 (8) Å, whereby the longer distance is associated with the apical ligand. The remaining chloride ligand is terminal at one of the basal positions, with a distance of 2.2272 (9) Å. In the crystal, the dimers are linked by inter-molecular O-H⋯O hydrogen bonds, together with N-H⋯O and N-H⋯Cl inter-actions involving the centrosymmetric organic cation, into a three-dimensional supra-molecular network. Further but weaker C-H⋯O and C-H⋯Cl inter-actions consolidate the packing.

"Heterogeneity within order" in metal-organic frameworks

Metal-organic frameworks (MOFs) are constructed by linking inorganic units with organic linkers to make extended networks. Though more than 20 000 MOF structures have been reported most of these are ordered and largely composed of a limited number of different kinds building units, and very few have multiple different building units (heterogeneous). Although heterogeneity and multiplicity is a fundamental characteristic of biological systems, very few synthetic materials incorporate heterogeneity without losing crystalline order. Thus, the question arises: how do we introduce heterogeneity into MOFs without losing their ordered structure? This Review outlines strategies for varying the building units within both the backbone of the MOF and its pores to produce the heterogeneity that is sought after. The impact this heterogeneity imparts on the properties of a MOF is highlighted. We also provide an update on the MOF industry as part of this themed issue for the 150th anniversary of BASF.

A tetranuclear copper cluster-based MOF with sulfonate–carboxylate ligands exhibiting high proton conduction properties

A tetranuclear copper cluster-based MOF with sulfonate–carboxylate ligands has been synthesized. It possesses 1D irregular channels lined with sulfonate, carboxylate, and DMF molecules, which show a high proton conductivity of 7.4 × 10⁻⁴ S cm⁻¹ at 95 °C and 95% relative humidity.

Controllable assembly of a three-dimensional metal-organic supramolecular framework displaying hydrogen-bonding and π-π stacking interactions

The complex poly[[aqua(μ2-phthalato-κ(2)O(1):O(2)){μ3-2-[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetato-κ(4)N(2),N(3):O:O'}{μ2-2-[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetato-κ(3)N(2),N(3):O}dizinc(II)] dihydrate], {[Zn2(C10H8N3O2)2(C8H4O4)(H2O)]·2H2O}n, has been prepared by solvothermal reaction of 2-[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetonitrile (PPAN) with zinc(II). Under hydrothermal conditions, PPAN is hydrolyzed to 2-[3-(pyridin-2-yl)-1H-pyrazol-1-yl]acetate (PPAA(-)). The structure determination reveals that the complex is a one-dimensional double chain containing cationic [Zn4(PPAA)4](4+) structural units, which are further extended by bridging phthalate ligands. The one-dimensional chains are extended into a three-dimensional supramolecular architecture via hydrogen-bonding and π-π stacking interactions.

High performance gas adsorption and separation of natural gas in two microporous metal–organic frameworks with ternary building units

Two MMOFs were assembled by the ternary SBU strategy and exhibited high adsorption selectivity for CO₂, C₂H₆ and C₃H₈ over CH₄.

Template-directed synthesis of metal–organic materials

This tutorial review details the emergence of template-directed synthesis of metal–organic materials (MOMs) with emphasis upon reports of MOMs in which the template is retained, template@MOMs, and structurally characterized.