Thermally/hydrolytically stable covalent organic frameworks from a rigid macrocyclic host

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) are crystalline porous polymers with tunable structures.
• Developing stable COFs for gas storage and separation is an active area of research.
• The synthesis of novel 2D COFs with enhanced properties is crucial for advanced applications.

Purpose of the Study:

• To synthesize and characterize two new two-dimensional (2D) covalent organic frameworks (COFs).
• To evaluate the thermal and hydrolytic stability of the synthesized COFs.
• To investigate the gas storage capabilities, specifically for hydrogen and carbon dioxide, of the new COFs.

Main Methods:

• Synthesis of two-dimensional COFs using triformylcyclotrianisylene as a building block.
• Characterization of COF structure, porosity, and stability using various analytical techniques.
• Gas sorption measurements to quantify hydrogen and carbon dioxide uptake capacities at specific conditions.

Main Results:

• Successful synthesis of two new 2D COFs, designated CTV-COF-1 and CTV-COF-2.
• Both COFs demonstrated significant thermal and hydrolytic stability.
• CTV-COF-1 (smaller pores) achieved 1.3 wt% hydrogen storage at low pressure.
• CTV-COF-2 (larger pores) exhibited high carbon dioxide uptake (250 cm³ g⁻¹ at 298 K and 50 bar).

Conclusions:

• The novel 2D COFs possess excellent stability, making them promising materials for practical applications.
• The pore size engineering in COFs allows for selective gas adsorption, demonstrated by differential hydrogen and CO2 uptake.
• These findings highlight the potential of tailored COFs for efficient gas storage and separation technologies.