Core–Shell Crystals of Porous Organic Cages

Abstract

The first examples of core–shell porous molecular crystals are described. The physical properties of the core–shell crystals, such as surface hydrophobicity, CO2 /CH4 selectivity, are controlled by the chemical composition of the shell. This shows that porous core–shell molecular crystals can exhibit synergistic properties that out‐perform materials built from the individual, constituent molecules.

The Chemistry of Porous Organic Molecular Materials

“…For example, solution processability allows core-shell materials to be produced where it is possible to tune both surface properties and gas selectivity. [20] Somewhat counterintuitively, porous molecular solids might have stability advantages: for example, the microporous imine POC CC3 is stable to boiling water without losing its crystallinity, [124] and acid-stable HOFs and POCs have been reported, [260,261,335] in some cases offering hydrolytic stability that is rivalled by very few crystalline porous materials. Also, structural "selfhealing" is possible: for example, porous molecular materials have been shown to recover crystallinity during guest absorption cycles.…”

“…This means that there are many opportunities to form new functional materials by postsynthetic processing techniques, and the examples given here constitute a small selection of the possibilities that exist. For example, solution processability allows core–shell materials to be produced where it is possible to tune both surface properties and gas selectivity 20. Somewhat counterintuitively, porous molecular solids might have stability advantages: for example, the microporous imine POC CC3 is stable to boiling water without losing its crystallinity,124 and acid‐stable HOFs and POCs have been reported,260,261,335 in some cases offering hydrolytic stability that is rivalled by very few crystalline porous materials.…”

“…This presents new opportunities in materials design, since the properties of porous molecular crystals can be tuned by chemically modifying the precursors, or by influencing their solid‐state packing. For example, mix‐and‐match strategies can be developed to modulate the properties of a molecular material 16–21. Also, organic molecules can be processed postsynthesis into different structures with contrasting properties 22–29.…”

“…For example, mix-andmatch strategies can be developed to modulate the properties of a molecular material. [16][17][18][19][20][21] Also, organic molecules can be processed postsynthesis into different structures with contrasting properties. [22][23][24][25][26][27][28][29] Guest responsive materials can also be designed to respond to external stimuli, [22,[30][31][32][33] and organic molecules can be processed into different materials forms, such as membrane supports for separations [34] or for sensing applications.…”

Selective adsorptive separation of cyclohexane over benzene using thienothiophene cages

“…Most recently, the easily scalable and processable organic cages with guest-adaptive porosity were successfully used in a wide range of adsorptive separations such xylene isomers separation. [28][29][30][31][32][33][34][35][36][37][38][39] Herein, we report an efficient method to successfully separate Cy from an equimolar Bz/Cy mixture by a thienothiophene organic cage (ThT-cage) with a selectivity of 94% and high recyclability (Scheme 1…”