Porous Shape-Persistent Organic Cage Compounds of Different Size, Geometry, and Function.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Chemistry

Background:

• Organic cages, crucial in supramolecular chemistry, were historically synthesized laboriously with low yields.
• Early methods like MacDowell's one-pot synthesis improved yields but were limited in scope.
• The author's group initiated research in 2008 with an adamantoid [4+6] imine cage.

Purpose of the Study:

• To explore efficient synthesis routes for shape-persistent organic cages.
• To investigate the gas sorption properties and structural factors influencing cage formation.
• To extend the application of organic cages in gas storage, separation, and sensing.

Main Methods:

• One-pot synthesis utilizing reversible imine condensation and boronic ester formation.
• Characterization of cage structures and porosity using techniques like Brunauer-Emmett-Teller (BET) analysis.
• Investigating the influence of substituents and functional groups on cage properties.
• Postfunctionalization of soluble porous units (SPUs) in solution and spray-coating for sensing.

Main Results:

• Achieved high specific surface areas (up to 3758 m²/g) for imine and boronic ester cages.
• Identified the crucial role of phenolic hydroxyl groups in directing cage formation and stability.
• Demonstrated selective gas sorption, including high CO2 adsorption (18.2 wt%) and preference for ethane over unsaturated hydrocarbons.
• Showcased the utility of soluble porous units (SPUs) for postfunctionalization and sensor development.

Conclusions:

• Efficient and high-yielding synthetic strategies for diverse organic cages have been established.
• Organic cages exhibit exceptional porosity and tunable properties for targeted applications.
• The solubility of these cages offers unique advantages for post-synthetic modification and device fabrication.