Bioinspired pore engineering in two-dimensional covalent organic frameworks

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) are porous materials with tunable structures.
• Existing 2D COFs primarily utilize eclipsed stacking, limiting certain functionalities.
• Biomolecular structures offer inspiration for advanced material design.

Purpose of the Study:

• To design and synthesize novel 2D COFs with amide side chains mimicking biomolecular hydrogen bonding.
• To investigate the adsorption capabilities of these COFs for iodine and iodide.
• To explore the role of crystalline structure versus amorphous networks in adsorption performance.

Main Methods:

• Synthesis of two-dimensional COFs (aCOFamide-1 and -2) with amide side chains.
• Characterization of COF structure and properties.
• Adsorption experiments for molecular iodine (I2) and iodide ions (I-).
• Computational electrostatic potential mapping.

Main Results:

• aCOFamide-1 and -2 demonstrated high iodine adsorption capacities (5.9-6.7 g g⁻¹).
• Antiparallel stacking in aCOFamides created nanotraps effective for iodide adsorption (1.3-1.7 g g⁻¹).
• Crystalline COFs showed superior adsorption compared to amorphous porous organic polymers (POPs).

Conclusions:

• Biomimetic design strategies can yield COFs with exceptional host-guest properties.
• Amide side chains in an antiparallel configuration enhance iodine and iodide adsorption.
• The crystalline nature of COFs is crucial for maximizing adsorption performance and reusability.