Topologically Rigidified Chiral Ionic Organic Crystals for High-Resolution Gas Chromatographic Separation

Abstract Chiral ionic organic crystals (CIOCs) have emerged as promising candidates for enantioseparation in gas chromatography (GC); however, conventional porous stationary phase materials often suffer from an intrinsic trade-off between efficient mass transfer within pores and sufficient stereochemical recognition. Herein, we present a conjugated structure-directed topological rigidification strategy for the rational engineering of CIOCs. Three CIOCs, BPDS-DBIM, TPDS-DBIM and TPDS-DBPIM, were constructed by regulating the conjugation length of ionic building blocks, revealing a progressive evolution from flexible ionic porous single crystals to highly ordered rigid channel architectures. The extension of conjugated backbones effectively reorganized the packing modes of cations and anions, leading to enhanced framework stability and tunable confined chiral microenvironments. Through further optimization of the molecular architecture, TPDS-DBPIM exhibited a more rigid framework with well-defined microporous features, indicating enhanced structural rigidity and stability relative to the less rigid ionic assembly. When used as the stationary phase in capillary GC, TPDS-DBPIM demonstrates superior enantiomeric separation performance, enabling efficient separation of 17 structurally distinct chiral drugs and a variety of chiral intermediates. Comprehensive thermodynamic and kinetic investigations further revealed that the rigidly confined microporous architecture serves as the key driving force governing the enhanced chiral recognition and mass-transfer behavior. This work addresses the long-standing mass transport and recognition trade-off in porous chromatographic materials and provides a molecular engineering paradigm for the development of next-generation high-resolution enantioseparation media.