A permanent mesoporous organic cage with an exceptionally high surface area

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Nanotechnology

Background:

• Porous organic cages (POCs) offer high surface areas but are often limited to micropores.
• Larger POCs tend to collapse upon solvent removal, hindering their practical application.
• Existing porous materials face challenges in achieving large pore sizes and stability.

Purpose of the Study:

• To synthesize a novel, shape-persistent porous organic cage with a large cavity.
• To investigate the gas sorption properties of the activated cage material.
• To overcome the limitations of microporosity and structural collapse in POCs.

Main Methods:

• Reversible covalent synthesis using triptycene tetraol and triboronic acid building blocks.
• Single-crystal X-ray diffraction for structural characterization and cavity size determination.
• Nitrogen gas sorption analysis to measure surface area and pore size distribution after activation.

Main Results:

• Successful synthesis of a shape-persistent cage compound with a cavity diameter of 2.6–3.1 nm.
• Activation of the porous molecular crystals by desolvation yielded a mesoporous material.
• Achieved a very high specific surface area of 3758 m²/g with a pore diameter of 2.3 nm.

Conclusions:

• The synthesized cage represents a significant advancement in creating large-cavity porous organic materials.
• The resulting mesoporous material exhibits excellent gas sorption properties, surpassing limitations of microporous analogues.
• This work opens new avenues for designing robust, large-pore POCs for advanced applications.