Site Partition in Metal‐Organic Framework for Temperature‐Responsive Adsorption Switching of C ₂ H ₂ and CO ₂

ABSTRACT The tunable adsorption preference of porous materials is highly desirable for enhancing their adaptability in complex separation processes, yet achieving such controllability remains a significant challenge and is rarely accomplished. Here, we demonstrate the practical feasibility of realizing switchable selective adsorption of C 2 H 2 and CO 2 through “adsorption site partition” within a pillar‐layered Zn(II)‐MOF, Zn‐ddtdc‐trz. The pocket structure near the Zn‐triazole layers creates a local “CO 2 ‐trap”, while the aromatic rings in the middle of the channel provide preferential binding sites for C 2 H 2 . This site‐partitioning arrangement, coupled with the 1D narrow capsule‐shaped channel, results in the temperature‐dependent adsorbate‐adsorbent binding and gas accumulation of C 2 H 2 and CO 2 , as evidenced by both in situ characterizations and theoretical calculations. Consequently, this MOF exhibits a selective adsorption of C 2 H 2 over CO 2 at 298 K (selectivity: 2.0 for 50:50 C 2 H 2 /CO 2 ), whereas shifts to preferentially adsorb CO 2 over C 2 H 2 with both moderate selectivity (1.5 for 50:50 CO 2 /C 2 H 2 ) and capacity (91.48 cm 3 g −1 , 250 K) at < 273 K, during static adsorption/breakthrough experiments. By showcasing how site partition could promote adsorption switching, this work deepens the understanding of molecular recognition in confined spaces under stimuli and highlights its potential for creating adaptable adsorbents with adjustable preferences for scenario‐specific applications.