Pyridazine‐Promoted Construction of Vinylene‐Linked Covalent Organic Frameworks with Exceptional Capability of Stepwise Water Harvesting

• Published in: Angewandte Chemie International Edition Vol. 63; no. 34; pp. e202402446 - n/a
• Main Authors: Mou, Kaiwen, Meng, Fancheng, Zhang, Zixing, Li, Xiaomeng, Li, Mengqi, Jiao, Yang, Wang, Zhiheng, Bai, Xue, Zhang, Fan
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 19.08.2024
• Edition: International ed. in English
• Subjects: covalent organic framework; Diffraction patterns; Hexagonal lattice; hydrogen bond; porous crystalline material; vinylene linkage; Water absorption; Water harvesting; Water uptake; X-ray diffraction; vinylene linkage; water harvesting; porous crystalline material; covalent organic framework; hydrogen bond
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202402446

In this study, we successfully developed two novel vinylene‐linked covalent organic frameworks (COFs) using 2‐connected 3,6‐dimethylpyridazine through Knoevenagel condensation. These COFs featured finely tailored micro‐/nano‐scale pore sizes, high surface areas and stable non‐polar vinylene linkages. Finely resolved powder X‐ray diffraction patterns demonstrated highly crystalline structures with a hexagonal lattice in the AA layer stacking. The resulting one‐dimensional channels possess strong hydrogen‐bond accepting sites arising from the decorated cis‐azo/azine units with two pairs of fully exposed lone pair electrons, endowing the as‐prepared COFs with exceptional water absorption properties. The g‐DZPH‐COF exhibited successive steep water uptake steps starting from low relative pressures (P/PSTA=0.1), with the remarkable water uptake capacity of 0.26 g/g at P/PSTA=0.2 (25 °C), which is the optimal value recorded among the reported COFs. Dynamic vapour sorption measurements revealed the fast kinetics of these COFs, even in the cluster formation process. Water uptake and release cycling tests demonstrated their outstanding hydrolytic stability, durability, and adsorption–desorption retention ability. Two COFs with non‐polar vinylene linkages were successfully constructed using 2‐connected 3,6‐dimethylpyridazine in Knoevenagel condensation, with high crystallinity, large surface areas, and finely tailored micro‐/nano‐channels decorated with substantial cis‐azo moieties, which exhibited exceptionally stepwise water uptake capacity.