Porous isoreticular non-metal organic frameworks

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Crystallography

Background:

• Metal-organic frameworks (MOFs) utilize metal nodes and organic linkers, relying on directional bonding for predictable structures via the isoreticular principle.
• Isoreticular strategies are limited in non-metal crystalline solids like organic salts due to less directional ionic bonding.

Purpose of the Study:

• To design metal-free porous organic frameworks using ammonium halide salts.
• To demonstrate the combination of chemical knowledge and computational crystal structure prediction (CSP) for designing novel porous materials.

Main Methods:

• Utilized computational crystal structure prediction (CSP) combined with chemical knowledge to design porous organic ammonium halide salts.
• Analyzed predicted lattice energy landscapes to identify stable, porous salt frameworks with predictable properties.
• Investigated the adsorption capabilities of the synthesized porous salts for molecular guests like iodine.

Main Results:

• Successfully designed and predicted porous organic ammonium halide salts containing no metals.
• Demonstrated that ionic clusters in these salt frameworks direct crystallization, evidenced by energy landscapes.
• Synthesized porous salts exhibiting high iodine adsorption capacities, surpassing many MOFs.
• Showcased scalable synthesis via simple acid-base neutralization.

Conclusions:

• A new class of non-metal porous organic frameworks based on ammonium halide salts has been developed.
• The strategy enables a priori prediction and control of framework porosity, channel size, and functionality.
• These materials offer promising applications in areas like radio-iodine capture due to their high adsorption capabilities and scalable synthesis.