High-resolution Performance of Leaning Pillar[6]arene Functionalized with Imidazolium Ionic Liquids for Gas Chromatography.

Leaning pillar[6]arene (LP6A) is an expanded version of pillar[6]arene (P6A), possessing not only the nanometer-sized cavity of P6A but also a unique desymmetrized leaning tower-like structure, which offers better structural flexibility and cavity adaptability. Here we report the first example of the utilization of imidazolium ionic liquid (IMIL) functionalized LP6A (LP6A-C10-IM-C8[NTf]) as a stationary phase in capillary gas chromatography (GC). The LP6A-C10-IM-C8[NTf] capillary column was prepared by the static coating method, showing medium polarity (average polarity 155) and high column efficiency (3758 plates/m). Using long alkyl chains modified LP6A (LP6A-C10) as a reference column, its retention behaviour and resolving performance were elucidated by a mixture of 30 analytes. Importantly, the LP6A-C10-IM-C8[NTf] column exhibited advantageous separation performance for the challenging isomers of halogenated benzenes, benzaldehydes, phenols, and anilines over the LP6A-C10 and commercial HP-5, HP-35, and DB-17 columns. In addition, the LP6A-C10-IM-C8[NTf] column has been used to determine the purity of isomer impurities in actual samples, demonstrating good potential in GC separations.