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

Abstract

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: mNT ≈ pNT > oNT. 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.

Keywords

Metal-organic pillar / 8-Hydroxyquinoline / Nitrotoluene isomers / Host-guest chemistry / Supramolecular chemistry / Molecule recognition / Crystal structure / Zinc

RIGHTS & PERMISSIONS

2026 SIOC, CAS, Shanghai, & WILEY-VCH GmbH