Engineering tunable rigid slits and supramolecular soft pockets on silica surfaces for multi-mode chromatographic...

Developing advanced chromatographic interfaces capable of discriminatively recognizing rigid structural isomers and highly polar environmental toxins remains a profound challenge. Herein, we report a systematic "structure-dictates-assembly" paradigm to engineer multi-mode polycyclic aromatic stationary phases with precisely controlled surface micro-topographies. Employing a dihydrazide-anchored thiol-ene click strategy on silica micro-particles, three distinct supramolecular architectures were fabricated: a highly aligned 2-phenanthrenyl phase (2-PNTHZD), a tilted angular 9-phenanthrenyl phase (9-PNTHZD), and a flat-oriented 9-anthracenyl phase (9-ANTHZD). Thermodynamic profiles and solvent-modulated responsive behaviors were comprehensively elucidated using diverse stereochemical and electronic probe matrices. The results reveal three divergent molecular recognition mechanisms. The 2-PNTHZD phase constructs high-density, liquid-crystal-like vertical rigid slits, achieving ultimate length-to-width ratio screening that perfectly segregates challenging tetracene and picene isomers. Conversely, the 9-PNTHZD creates a spatially tilted angular pocket for bent isomers, which remarkably transitions into a highly flexible supramolecular "soft pocket" via active acetonitrile intercalation. This solvent-driven induced-fit mechanism provides a distinct departure from classical reversed-phase thermodynamics, unlocking the baseline resolution of heavily twisted polybrominated biphenyl (PBB) congeners. Furthermore, free from lateral steric hindrance, the wide-open 9-ANTHZD functions as an exceptional π-electron donor surface, leveraging its high HOMO energy to conquer electron-deficient perfluorocarbons and deliver peak-capacity breakthroughs for EPA 529 nitro-explosives. Collectively, this work introduces a highly tunable, multi-mode surface platform, providing a fundamentally predictable toolkit for complex environmental and structural isomer analysis.