Covalent Organic Frameworks for Carbon Dioxide Capture from Air

ABSTRACT: We report the first covalent incorporation of reactive aliphatic amine species into covalent organic frameworks (COFs). This was achieved through the crystallization of an iminelinked COF, termed COF-609-Im, followed by conversion of its imine linkage to base-stable tetrahydroquinoline linkage through aza-Diels-Alder cycloaddition, and finally, the covalent incorporation of tris(3-aminopropyl)amine into the framework. The obtained COF-609 exhibits a 1360-fold increase in CO2 uptake capacity compared to the pristine framework and a further 29% enhancement in the presence of humidity. We confirmed the chemistry of framework conversion and corroborated the enhanced CO2 uptake phenomenon with and without humidity through isotope-labeled Fourier transform infrared spectroscopy and solidstate nuclear magnetic resonance spectroscopy. With this study, we established a new synthetic strategy to access a class of chemisorbents characterized by high affinity to CO2 in dilute sources, such as the air.

Automated summary

This study reports the covalent incorporation of reactive aliphatic amine species into covalent organic frameworks (COFs) for the first time. Through crystallization and chemical reactions, tris(3-aminopropyl)amine was successfully incorporated into COF-609, resulting in a significant enhancement in CO2 uptake capacity.