Post-synthetic modification of a highly flexible 3D soft porous metal–organic framework by incorporating conducting polypyrrole: enhanced MOF stability and capacitance as an electrode material

Porous, stable and functional MOF polymer hybrids can be prepared by the in situ polymerization of otherwise unstable soft crystals.

Solvent-assisted delamination of layered copper dithienothiophene-dicarboxylate (DUT-134)

Rational selection of the delamination solvent enables efficient exfoliation of layered MOF, resulting in suspension of the nanosheets stable over days.

Emerging porous materials in confined spaces: from chromatographic applications to flow chemistry

Porous materials confined within capillary columns/microfluidic devices are discussed, and progress in chromatographic and membrane separations and catalysis is reviewed.

Thermal and Guest-Assisted Structural Transition in the NH₂-MIL-53(Al) Metal Organic Framework: A Molecular Dynamics Simulation Investigation

Reversible structural transition between the Large (LP) and Narrow Pore (NP) forms (breathing phenomena) of the MIL-53(X, X = Al, Cr, Fe, Ga) Metal Organic Framework (MOF) is probably one of the most amazing physical properties of this class of soft-porous materials. Whereas great attention has been paid to the elucidation of the physical mechanism ruling this reversible transition, the effect of the functionalization on the flexibility has been less explored. Among functionalized MIL-53(Al) materials, the case of NH2-MIL-53(Al) is undoubtedly a very intriguing structural transition rarely observed, and the steadier phase corresponds to the narrow pore form. In this work, the flexibility of the NH2-MIL-53(Al) metal organic framework was investigated by means of molecular dynamics simulations. Guest (methanol) and thermal breathing of the NH2-MIL-53(Al) was thus explored. We show that it is possible to trigger a reversible transition between NP and LP forms upon adsorption, and we highlight the existence of stable intermediate forms and a very large pore phase. Furthermore, the NP form is found thermodynamically stable from 240 to 400 K, which is the result of strong intramolecular hydrogen bonds.

An Unprecedented Stimuli-Controlled Single-Crystal Reversible Phase Transition of a Metal-Organic Framework and Its Application to a Novel Method of Guest Encapsulation

The flexibility and unexpected dynamic behavior of a third-generation metal-organic framework are described for the first time. The synthetic strategy is based on the flexibility and spherical shape of dipyridyl-based carborane linkers that act as pillars between rigid Co/BTB (BTB: 1,3,5-benzenetricarboxylate) layers, providing a 3D porous structure (1). A phase transition of the solid can be induced to generate a new, nonporous 2D structure (2) without any loss of the carborane linkers. The structural transformation is visualized by snapshots of the multistep single-crystal-to-single-crystal transformation by single-crystal and powder X-ray diffraction. Poor hydrogen bond acceptors such as MeOH, CHCl3 or supercritical CO2 induce such a 3D to 2D transformation. Remarkably, the transformation is reversible and the 2D phase 2 is further converted back into 1 by heating in dimethylformamide. The energy requirements involved in such processes are investigated using periodic density functional theory calculations. As a proof of concept for potential applications, encapsulation of C60 is achieved by trapping this molecule during the reversible 2D to 3D phase transition, whereas no adsorption is observed by straight solvent diffusion into the pores of the 3D phase.

Future Porous Materials

Developing science and technology of porous materials provides fuels and useful substances from ubiquitous gaseous substances such as air.

Site-selective Eu(iii) spectroscopy of highly efficient luminescent mixed-metal Pb(ii)/Eu(iii) coordination polymers

Novel coordination polymers based on Pb_1−xEu_x–BDC (x = 0.05–0.50, BDC = 1,4-benzenedicarboxylic acid) are reported with a maximum emission quantum yield of 69 ± 7%.

From helix to helical pores: solid-state crystalline conversions triggered by gas–solid reactions

Solid-state crystalline conversions of one-dimensional (1D) helical coordination polymers CuBIm–Cl and CuBIm–Br to a gyrodial metal–organic framework (MOF) STU-3 which is composed of Cu ions and Bim ligands are observed through a gas–solid reaction, where the gas is methylamine.