One Flexible Metal–Organic Framework with Guest‐Adaptive Rotational Valve for Gas Separation

Abstract The dynamic structural properties of flexible metal–organic frameworks (MOFs) endow them with a unique ability to recognize guest molecules. However, designing a flexible MOF that is sensitive to guest molecules and can recognize one target molecule from gas mixtures that have weak interactions with the adsorbent remains a challenge. Herein, a “guest‐adaptive rotational valve” strategy is proposed that introduces a guest‐adaptive rotating 3D linker into a 1D confined channel of locally flexible MOF (CoNi‐TED) to address this challenging separation. Under the collaboration of adaptive rotating linkers and dense open metal sites, CoNi‐TED displays record CH ₄ /N ₂ selectivity (23.5) and CH ₄ /N ₂ uptake ratio (8.64) at 298 K and 1 bar. Breakthrough experiments and pressure swing adsorption (PSA)simulations show that it can produce CH ₄ with a good balance between purity and recovery. Besides, it shows high structural stability and can be scaled up to a kilogram scale under simple and gentle synthesis conditions, rendering it a new benchmark adsorbent for natural gas purification.