A Permanent Mesoporous Organic Cage with an Exceptionally High Surface Area

Soluble Tetraaminotriptycene Precursors

An efficient route to soluble triptycene tetraamines, shape-persistent molecules containing two ortho-phenylenediamine motifs, is reported. These tetraamines are stable, prepared in good yields, easily purified by column chromatography, and can be readily condensed to give a range of imidazole and pyrazine derivatives.

One-step synthesis of a cyclic 2,17-dioxo[3,3](4,4') biphenylophane and first preparation of a microporous polymer network from a macrocyclic precursor by cyclotrimerization

One-step synthesis of a cyclic 2,17-dioxo[3,3](4,4')biphenylophane (MC) was achieved in high yield; its structure was verified by single crystal X-ray analysis. As a first example, a microporous polymer network was formed from macrocycle MC via acid-catalysed cyclotrimerization yielding a BET surface area of ca. 570 m(2) g(-1).

Self-assembly of dynamic orthoester cryptates

The discovery of coronands and cryptands, organic compounds that can accommodate metal ions in a preorganized two- or three-dimensional environment, was a milestone in supramolecular chemistry, leading to countless applications from organic synthesis to metallurgy and medicine. These compounds are typically prepared via multistep organic synthesis and one of their characteristic features is the high stability of their covalent framework. Here we report the use of a dynamic covalent exchange reaction for the one-pot template synthesis of a new class of coronates and cryptates, in which acid-labile O,O,O-orthoesters serve as bridgeheads. In contrast to their classic analogues, the compounds described herein are constitutionally dynamic in the presence of acid and can be induced to release their guest via irreversible deconstruction of the cage. These properties open up a wide range of application opportunities, from systems chemistry to molecular sensing and drug delivery.

Cryptands and related molecules are macrocyclic polyethers capable of strongly binding cations. Here, the authors use orthoester exchange for the dynamic one-pot synthesis of crypates, which can bind cations and, given their constitutionally dynamic nature, can also be decomposed to release their guest.

Absorbate-induced piezochromism in a porous molecular crystal

Atmospherically stable porous frameworks and materials are interesting for heterogeneous solid-gas applications. One motivation is the direct and selective uptake of pollutant/hazardous gases, where the material produces a measurable response in the presence of the analyte. In this report, we present a combined experimental and theoretical rationalization for the piezochromic response of a robust and porous molecular crystal built from an extensively fluorinated trispyrazole. The electronic response of the material is directly determined by analyte uptake, which provokes a subtle lattice contraction and an observable bathochromic shift in the optical absorption onset. Selectivity for fluorinated absorbates is demonstrated, and toluene is also found to crystallize within the pore. Furthermore, we demonstrate the application of electronic structure calculations to predict a physicochemical response, providing the foundations for the design of electronically tunable porous solids with the chemical properties required for development of novel gas-uptake media.

Dynamic flow synthesis of porous organic cages

Two imine-based porous organic cages were successfully synthesised in continuous flow. The same flow reactor was then used to scramble the constituents of these two cages in differing ratios to form cage mixtures.

Targeted synthesis of a large triazine-based [4+6] organic molecular cage: structure, porosity and gas separation

A novel electron-deficient triazine-based [4+6] organic molecular cage has been synthesized via imine condensation reaction.

Crystal-to-crystal structural transformation of hydrogen-bonding molecular crystals of (imidazolium)(3-hydroxy-2-quinoxalinecarboxylate) through H2O adsorption–desorption

Crystal-to-crystal structural transformation was observed following H₂O adsorption–desorption of hydrogen-bonding molecular crystals.

Continuous flow synthesis of a carbon-based molecular cage macrocycle via a three-fold homocoupling reaction

The facile synthesis of the cage molecule (C₁₁₀H₅₆Br₂) via a remarkable three-fold homo-coupling macrocyclization reaction using continuous flow methodology is reported.

Controlling the assembly of cyclotriveratrylene-derived coordination cages

Ligand-functionalised cyclotriveratrylene derivatives self-assemble to afford coordination cages and topologically non-trivial constructs, including controlled assembly of M₃L₂ metallo-cryptophane and M₆L₈ cages.

Hierarchical supramolecules and organization using boronic acid building blocks

Current progress on hierarchical supramolecules using boronic acids has been highlighted in this feature article. The feasibility of the structure-directing ability is fully discussed from the standpoint of the generation of new smart materials.

Syntheses, crystal structures and properties of three cyano-bridged one-dimensional coordination polymers based on macrocyclic metallic tectons

Three complexes based on macrocyclic metallic tectons and [Ni(CN)₄]²⁻ have been reported. Interestingly, complex 1 features an unexpected large porous structure with a pore size of 1 nm, which shows two-step adsorption of CO₂ gas at 195 K.

Porous frameworks constructed by non-covalent linking of substitution-inert metal complexes

Flexible porous frameworks based on substitution-inert paddle-wheel Rh(ii) dimers with active sites were successfully synthesized by using multipoint arene-perfluoroarene interactions and the porous properties of the frameworks were investigated.

Synthesis of a rigid C3v -symmetric tris-salicylaldehyde as a precursor for a highly porous molecular cube

The development of a synthetic approach to a C3v -symmetric tris-salicylaldehyde based on triptycene is presented. The tris-salicylaldehyde is a versatile precursor for porous molecular materials, as demonstrated in the [4+4] condensation reaction with a triptycene triamine to form a molecular shape-persistent porous cube. The amorphous material of the molecular porous cube shows a very high surface area of 1014 m(2)  g(-1) (BET model) and a high uptake of CO2 (18.2 wt % at 273 K and 1 bar). Furthermore, during the multistep synthesis of the tris-salicylaldehyde precursor, a relatively rare (twofold) addition of the aryne to the anthracene in the 1,4- and 1,4,5,8-positions have been found during a Diels-Alder reaction, as proven by X-ray structure analysis.

Separation of rare gases and chiral molecules by selective binding in porous organic cages

The separation of molecules with similar size and shape is an important technological challenge. For example, rare gases can pose either an economic opportunity or an environmental hazard and there is a need to separate these spherical molecules selectively at low concentrations in air. Likewise, chiral molecules are important building blocks for pharmaceuticals, but chiral enantiomers, by definition, have identical size and shape, and their separation can be challenging. Here we show that a porous organic cage molecule has unprecedented performance in the solid state for the separation of rare gases, such as krypton and xenon. The selectivity arises from a precise size match between the rare gas and the organic cage cavity, as predicted by molecular simulations. Breakthrough experiments demonstrate real practical potential for the separation of krypton, xenon and radon from air at concentrations of only a few parts per million. We also demonstrate selective binding of chiral organic molecules such as 1-phenylethanol, suggesting applications in enantioselective separation.

Triptycene-based Organic Molecules of Intrinsic Microporosity

Four Organic Molecules of Intrinsic Microporosity (OMIMs) were prepared by fusing triptycene-based components to a biphenyl core. Due to their rigid molecular structures that cannot pack space efficiently, these OMIMs form amorphous materials with significant microporosity as demonstrated by apparent BET surface areas in the range of 515-702 m(2) g(-1). Bulky cyclic 1',2',3',4'-tetrahydro-1',1',4',4'-tetramethylbenzo units placed on the triptycene termini are especially efficient at enhancing microporosity.

Predicted crystal energy landscapes of porous organic cages

Computational methods predict the crystal packing of porous organic cage molecules, allowing crystal structure and porosity to be predicted starting from the chemical diagram alone.

Dynamic covalent assembly of tribenzotriquinacenes into molecular cubes

Molecular cubes constructed from catechol-functionalized tribenzotriquinacenes and 1,4-phenylene diboronic acids were synthesized in a one-pot procedure by crosslinking 20 individual components through a dynamic covalent approach.