Hydrazine-Hydrazide-Linked Covalent Organic Frameworks for Water Harvesting

Ha L Nguyen; Cornelius Gropp; Nikita Hanikel; Anna Möckel; Alicia Lund; Omar M Yaghi

doi:10.1021/acscentsci.2c00398

Hydrazine-Hydrazide-Linked Covalent Organic Frameworks for Water Harvesting

ACS Cent Sci. 2022 Jul 27;8(7):926-932. doi: 10.1021/acscentsci.2c00398. Epub 2022 Jun 16.

Authors

Ha L Nguyen^{1

2}, Cornelius Gropp¹, Nikita Hanikel¹, Anna Möckel¹, Alicia Lund³, Omar M Yaghi^{1

2}

Affiliations

¹ Department of Chemistry, University of California-Berkeley, Kavli Energy Nanoscience Institute at UC Berkeley; and Berkeley Global Science Institute, Berkeley, California 94720, United States.
² Joint UAEU-UC Berkeley Laboratories for Materials Innovations, United Arab Emirates University, Al-Ain 15551, United Arab Emirates.
³ Department of Chemistry, University of California-Berkeley, Berkeley, California 94720, United States.

Abstract

We report a postsynthetic strategy and its implementation to make covalent organic frameworks (COFs) with irreversible hydrazide linkages. This involved the synthesis of three 2D and 3D hydrazine-linked frameworks and their partial oxidation. The linkage synthesis and functional group transformation-hydrazine and hydrazide-were evidenced by ¹⁵N multi-CP-MAS NMR. In addition, the isothermal water uptake profiles of these frameworks were studied, leading to the discovery of one hydrazine-hydrazide-linked COF suitable for water harvesting from air in arid conditions. This COF displayed characteristic S-shaped water sorption profiles, a steep pore-filling step below 18% relative humidity at 25 °C, and a total uptake capacity of 0.45 g g^-1. We found that even small changes made on the molecular level can lead to major differences in the water isotherm profiles, therefore pointing to the utility of water sorption analysis as a complementary analytical tool to study linkage transformations.