Cucurbit(6)uril immobilized on silica: a novel high-performance liquid chromatographic stationary phase

In the present study, one of the new generation of host molecules, cucurbit(6)uril (CB(6)), was immobilized onto silica (CB(6)/SiO2 ) by a sol-gel approach. CB(6)/SiO2 was characterized by NMR spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis. It was used as a high-performance liquid chromatographic stationary phase and its chromatographic performance was systematically investigated with different types of analytes as probes. The results revealed that the CB(6)/SiO2 stationary phase exhibited weak hydrophobic and strong hydrophilic properties. Hence, the variables for hydrophilic interaction liquid chromatography, including components and pH of the mobile phase, were further investigated to explore the retention mechanism of this CB(6)/SiO2 stationary phase. For less polar analytes, both hydrophobic and hydrophilic interactions could contribute to the retention, while for polar analytes, hydrophilic interaction may be predominant. Compared to the tetraethoxylsilane-coated SiO2 stationary phases, the CB(6)/SiO2 stationary phase exhibited a different retention behavior toward basic analytes with excellent stability. It is a novel promising hydrophilic interaction liquid chromatography stationary phase.