A Dual Locking Strategy Enables Highly Selective meta ‐Xylene Separation With an Aluminum‐Pyrrolic Framework

Efficient separation of xylene isomers remains a significant challenge due to their nearly identical physicochemical properties. Here, we report a dual locking strategy in an aluminum–pyrrolic framework (Al‐PyDC) with V‐shaped ligand featured AlO 6 chains and pyrrole dual recognition sites that simultaneously stabilize the V‐shaped meta ‐xylene (mX). This dual‐locking effect promotes dense packing of mX within confined channels, resulting in a high adsorption capacity for mX (4.0 mmol g −1 ), which is much higher than that for ortho ‐xylene (oX, 2.5 mmol g −1 ) and para ‐xylene (pX, 2.0 mmol g −1 ). The simulations and solid‐state NMR spectroscopy further confirmed that mX experienced stronger locking interactions with the AlO 6 chains and pyrrolic ligands compared to pX. Notably, the dual locking effect was temperature‐dependent, and elevated temperature accelerated molecular diffusion, thereby weakening the effectiveness of the recognition. Hence, Al‐PyDC achieved an excellent mX/pX selectivity of 8.0 in vapor‐phase breakthrough measurements at ambient temperature (303 K), which outperformed most of the MOF counterparts. Additionally, the isomorphic CAU‐10‐H with V‐shaped AlO 6 –phenyl–AlO 6 dual locking sites was employed as a control material to elucidate the role of active‐site in molecular recognition. This dual locking strategy offered an effective approach for enhancing the adsorption capacity and selectivity for challenging isomer separations.