Homochiral Organic Molecular Cage Rcc3-R-Modified Silica as a New Multi-Mode and Multi-Functional Stationary Phase for High Performance Liquid Chromtagraphy

In this study, homochiral reduced imine cage (RCC3-R) was covalently bonded to the surface of silica gel to prepare a novel high performance liquid chromatography (HPLC) stationary phase applied for the multiple separation modes such as normal phase (NP), reversed-phase (RP), ion exchange (IE) and hydrophilic interaction chromatography (HILIC). The successful preparation of RCC3-R bonded silica stationary phase was confirmed by a series of methods including X-ray photoelectron spectroscopy, thermogravimetric analysis and infrared spectroscopy. The results of chiral resolution in NP and RP modes showed that seven chiral compounds were successfully separated, among which the resolution of 1-phenylethanol reached 3.97. The multi-functional chromatographic performance of the new molecular cage stationary phase was systematically investigated by various analytes (alkylbenzene homologues, polycyclic aromatic hydrocarbons, phenols, amines, sulfonamides, acids and nucleosides) in RP, IE and HILIC modes, which proved that multiple interactions of hydrophilic, hydrophobic, π-π, dipole–dipole, hydrogen-bonding and ion-exchange provided by benzene rings, cyclohexane and secondary amines can be simultaneously existed between the stationary phase and the analytes. In addition, the stationary phase showed good reproducibility and stability. This work demonstrated that RCC3-R not only achieved multi-mode and multi-functional separation performance, but also expanded the application of organic molecular cage in the field of HPLC chromatography.