Confinement of p‐Xylene in the Pores of a Bilanthanide Metal–Organic Framework for Highly Selective Recognition

Abstract The rapid and accurate sensing of p ‐xylene, an essential raw material with a multi‐billion‐dollar market, in xylene mixture is of great significance in industry; however, the highly similar molecular structures, energy levels, and spectral characteristics of xylene isomers make the selective recognition extremely challenging. Metal–organic frameworks (MOFs) exhibiting tailorable pores and potential binding sites provide prospects for xylene sensing but a comprehensive understanding of the pore effect is still elusive, primarily due to the intricacies involved in the sensing process. Herein, we reported a robust bilanthanide MOF NKU‐999‐EuTb with precisely engineered pores to accommodate p ‐xylene, of which the binding sites were confirmed by single crystal X‐ray diffraction and dynamic magnetic susceptibilities. NKU‐999‐EuTb exhibits high‐performance in selective recognition for p‐ xylene towards its isomers. Through a systematical study, it was revealed that absorbing p ‐xylene into the pores governs the sensing performance. This work provides insights for developing advanced sensing materials for complex isomers.