Covalent Organic Frameworks for Carbon Dioxide Capture from Air

• Published in: Journal of the American Chemical Society Vol. 144; no. 28; pp. 12989 - 12995
• Main Authors: Lyu, Hao, Li, Haozhe, Hanikel, Nikita, Wang, Kaiyu, Yaghi, Omar M.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 20.07.2022
• Subjects: air; carbon dioxide; crystallization; cycloaddition reactions; Fourier transform infrared spectroscopy; humidity; imines; isotope labeling; nuclear magnetic resonance spectroscopy
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.2c05382

We report the first covalent incorporation of reactive aliphatic amine species into covalent organic frameworks (COFs). This was achieved through the crystallization of an imine-linked 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 solid-state 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.