Luo Pan, Peng Jingdong, Peng Huanjun, Zhang Zilong, Chen Jun, Fan Kun, Wang Xiang
School of Chemistry and Chemical Engieering, Southwest University, Chongqing 400715, China.
School of Chemistry and Chemical Engieering, Southwest University, Chongqing 400715, China.
J Chromatogr A. 2023 Jan 25;1689:463773. doi: 10.1016/j.chroma.2023.463773. Epub 2023 Jan 3.
The structural properties of ionic liquid stationary phases have a considerable effect on their separation selectivity. However, the difference of the chromatographic retention behavior of different regioisomeric ionic liquid stationary phases has rarely been investigated. In this study, three regioisomeric ionic liquid silane reagents were prepared by photoinitiated ene-click chemistry and bonded to silica by one-pot method to fabricate three new stationary phases (Sil-C2Im-C8, Sil-C6Im-C4, and Sil-C9Im-C1). All three stationary phases showed promising retention repeatability and efficiency. The retention behavior of the three stationary phases was investigated under various chromatographic conditions. The retention mechanism was further investigated by the linear energy solvation relationship and Van't Hoff plots. The stationary phases exhibited mixed-mode retention mechanisms. The π-π, hydrogen bonding, ion-exchange, and hydrophilic interactions with analytes were the weakest when the imidazole ions were embedded in the innermost part of the alkyl chains, while the interactions were the strongest when the imidazole ions were embedded in the middle of the alkyl chains. The three stationary phases provided great but different separation performances towards nucleosides, nucleobases, aromatic acids, alkyl benzenes, and polycyclic aromatic hydrocarbons due to the influence of imidazole ion position.
离子液体固定相的结构性质对其分离选择性有相当大的影响。然而，不同区域异构体离子液体固定相的色谱保留行为差异很少被研究。在本研究中，通过光引发的烯点击化学制备了三种区域异构体离子液体硅烷试剂，并通过一锅法将其键合到硅胶上，以制备三种新型固定相（Sil-C2Im-C8、Sil-C6Im-C4和Sil-C9Im-C1）。所有三种固定相均表现出良好的保留重复性和柱效。在各种色谱条件下研究了这三种固定相的保留行为。通过线性溶剂化能关系和范特霍夫图进一步研究了保留机理。固定相表现出混合模式的保留机理。当咪唑离子嵌入烷基链的最内部时，与分析物的π-π、氢键、离子交换和亲水相互作用最弱，而当咪唑离子嵌入烷基链中间时，相互作用最强。由于咪唑离子位置的影响，这三种固定相对核苷类、核苷碱基、芳香酸、烷基苯和多环芳烃具有不同但良好的分离性能。
