Unravelling the nanoarchitectonics of -C-N- linkages in covalent organic frameworks for CO2 capture-a mini-review

Abstract

Covalent Organic Frameworks (COFs) featuring carbon-nitrogen (C-N) linkages represent a versatile class of crystalline, porous materials constructed through the dynamic covalent bonding of organic monomers. Schiff-base, C-N imine-linked COFs have garnered considerable interest for carbon dioxide (CO₂) capture owing to their highly tunable structures, excellent thermal and chemical stability, and enduring porosity, which stem from their robust architectures and nitrogen-rich composition. The inherent polarity and Lewis basicity of C-N bonds promote strong CO₂ adsorption via dipole-quadrupole and hydrogen bonding interactions, enhancing uptake and selectivity, particularly under low-pressure or humid conditions, making them ideal for real-world applications in CO₂ capture. Key structural attributes, such as nanoarchitectures based on small pore sizes, electron-rich substituents, and three-dimensional multi-layered frameworks, further enhance both stability and CO₂ affinity by reinforcing π-conjugation and improving weak supramolecular interactions. This mini-review delves into the mechanistic role of C-N connectivity in influencing CO₂ gas affinity and framework stability, highlighting a promising pathway for the rational design of next-generation COFs for carbon dioxide capture and storage technologies.