High-resolution performance of pillar[6]arene functionalized with imidazolium ionic liquids for gas chromatography

Pillar[ n ]arenes (P[ n ]A, n  = 5–10) have attracted much attention because of their highly symmetric pillar-shaped architecture with π -electron rich cavity. Nevertheless, the use of ionic liquid functionalized P[ n ]A in chromatography has not been reported up to data. This work reports the investigation of the imidazolium ionic liquids functionalized pillar[6]arene (P6A-C10-IM-C8[NTf 2 ]) as the stationary phase for gas chromatography (GC). The statically coated P6A-C10-IM-C8[NTf 2 ] column (0.25 mm i.d.) showed moderate polarity and high column efficiency of 4733 plates/m determined by n -dodecane at 120 °C ( k  = 2.29). Owing to its unique amphiphilic conformation, the P6A-C10-IM-C8[NTf 2 ] showed good column inertness and resolving capability for a wide range of analytes and isomers. Particularly, the P6A-C10-IM-C8[NTf 2 ] column exhibited distinctly advantageous performance for the challenging isomers of halogenated benzenes, benzaldehydes, phenols and anilines over the common commercial columns, namely 5% phenyl methyl polysiloxane (HP-5) and 35% phenyl methyl polysiloxane (HP-35). In addition, it exhibited good column repeatability and reproducibility with RSD values on the retention times less than 0.05% for run-to-run, 0.38% for day-to-day and 2.94% for column-to-column, respectively. This work demonstrates the promising future of ionic liquid P[ n ]A stationary phases for chromatographic separations.