Crystallization‐Embedded Molecular Recognition: Single‐Step Nitrotoluene Isomers Discrimination by a Metal‐Organic Pillar

Comprehensive Summary The selective recognition of nitrotoluene isomers remains a considerable challenge in environmental monitoring and chemical sensing. Herein, we report the selective recognition behavior toward nitrotoluene isomers exhibited by a metal‐organic pillar (MOP) during its crystallization. A binuclear MOP 1 , constructed via coordination‐driven self‐assembly of a bidentate organic ligand and Zn II cations, exhibits distinct host–guest behavior toward different nitrotoluene isomers. Single‐crystal X‐ray diffraction analysis reveals that m ‐nitrotoluene and p ‐nitrotoluene form well‐defined host‐guest inclusion complexes within the cavity of MOP 1 via multiple CH···π and OH···O interactions between the guests and the host. In contrast, o ‐nitrotoluene undergoes mere mechanical co‐crystallization without specific cavity inclusion. Crystallographic studies and DFT calculations establish the recognition order: m NT ≈ p NT > o NT. This study merges MOP synthesis and selective recognition into a single crystallization step, offering an efficient and conceptually novel strategy for the recognition of nitrotoluene isomers.