Confining the Node Accessibility of Zr-MOFs Along One-Dimensional Channels Toward High Water-Vapor Cycle-Stability

Zirconium-based MOFs (Zr-MOFs) with high hydrolytic stability are promising materials for water-adsorption-related applications. However, besides hydrolytic stability, cycling stability is also a crucial feature that renders a MOF a good candidate for water adsorption. Through a series of Zr-MOFs with one-dimensional (1D) channels showing high water cycling stability, a principle of confining the accessibility of Zr₆ nodes aligning along channel direction in Zr-MOFs was unveiled. According to this principle, several topologies that regulates Zr₆ nodes with chelating formate aligning in a same plane with a distance less than 5.4 Å can successfully hinder the introduction of in-plane water molecules, thus significantly improve the cycling stability of Zr-MOFs for water adsorption. Along with this principle, we illustrated a linker designing strategy by horizontal extending the core of organic linkers toward the synthesis of Zr-MOFs with similar node alignment. By either intentionally shortening or elongating the core horizontally, both MOFs shows high water-vapor cycling stability. Among them, NJTech-5 (NJTech for Nanjing Tech University) with scu-topology, presents a water uptake capacity of 0.93 g g^-1 and working capacity of 0.82 g g^-1, making it among the top stable MOFs with high water uptake capacity and a promising candidate for indoor humidity control.