A Durable Metal–Organic Framework with a Hydrophobic sp ³ ‐Carbon‐Rich Nanospace Constructed from Flexible Medium‐Sized Ring Ligands

Despite the high design freedom of metal-organic frameworks (MOFs), flexible ligands that bear sp³-hybridized carbon atoms in their core are generally avoided as building blocks for MOFs because they may compromise framework stability. Herein, a 2D MOF (CBoard) is reported incorporating a dibenzocyclooctadiene with a flexible medium-sized ring at the core as a flexible ligand. The moderate flexibility of the incorporated dibenzocyclooctadiene in CBoard reduces the strain induced by external stimuli on the coordination bonds, conferring cyclic stability upon guest adsorption-desorption. Furthermore, the sp³-hybridized carbon-rich nanospace endows CBoard with water resistance and surface hydrophobicity. This hydrophobic nanospace preferentially captures ethanol over water, highlighting its potential for applications in ethanol-water separation in dilute aqueous solutions.