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

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.