Application Of Calixarene Ionic Liquid In Gas Chromatography

In the field of gas chromatography,the development of new stationary phases with high selectivity and stable physical and chemical properties has always been one of the hot issues for researchers.In this paper,calixarene was used as the main body to prepare gas chromatographic stationary phases by chemical bonding and physical mixing methods,and their retention behavior,separation performance and structure-activity relationship were deeply studied.This paper mainly includes the following four parts:（1）Calix[4]arene bonded ionic liquids（[C4A-Bim][NTf₂]and[C4RA-Bim][NTf₂]）were synthesized.The effects of anion exchange of the materials on the thermal stability were studied by thermogravimetric analysis.The results shown that the thermal stability of calixarene ionic liquids after anion exchange was better than before ion exchange,which could reach 284℃and 347℃respectively.In addition,the separation results of two stationary phases for Grob mixtures indicated that they had certain separation ability.（2）Calix[4]arene derivative（C4A-NH₂）and valine imidazole ionic liquids([C₁mim Val][NTf₂]and[C₁₂mim Val][NTf₂])were synthesized.C4A-NH₂/[C₁mim Val][NTf₂]and C4A-NH₂/[C₁₂mim Val][NTf₂]stationary phases were prepared by physical mixing method.The separation results indicated that the two stationary phases had good separation ability for the Grob mixtures and different types of analytes.In addition,calixarene/ionic liquid stationary phases had reach baseline separation for aniline isomers,and their resolutions（R）were significantly better than single calixarene,ionic liquid and commercial columns（HP-35,DB-17）.（3）Calix[6]arene derivative（C6A-C10-OH）was synthesized and its crystal and molecular structure was studied by single crystal diffraction analysis（X-Ray）.Compared with C6A-C10,there are two phenolic hydroxyl groups at the lower rim of C6A-C10-OH,which makes them different in polarity and separation performance.C6A-C10-OH had greater polarity and longer retention time for polar alcohol analytes than C6A-C10.（4）Calix[4]arene derivative（C4A-PEG）was synthesized,and C4A-PEG column was prepared by static method.The separation results shown that C4A-PEG had good symmetrical peak shape and separation ability for Grob mixtures and 23 analytes.In particular,the resolutions（R）of C4A-PEG for toluidine and xylidine isomers were significantly better than calix[4]arene and polysiloxane HP-35 commercial column.The results suggested that the separation ability of calixarene after derivatization had been greatly improved.