Preparation of a high-density vinyl silica gel to anchor cysteine via photo-click reaction and its applications in hydrophilic interaction chromatography

Modification of surface silanols is a topic of interest in the preparation of organo-functionalized silica particles. Herein, two novel contributions, mainly focused on separation science, were presented: i) the horizontal polymerization on silica surface by using the vinyl-triacetoxy silane and ii) a preparation of cysteine-based stationary phase via photo-click thiol-ene coupling. In the first derivatization step, the vinyl-triacetoxy silane was employed instead of conventional trichloro vinyl one. The one-step synthetic procedure needed imidazole as an activating agent in addition to the silica hydration. Modified silica particles offer a high loading of vinyl fragments and an extensive passivation of silanols such as to not require a subsequent end-capping procedure. The structural morphology of media was deeper characterized by combining infrared spectroscopy, solid-state nuclear magnetic resonance, and elemental analysis. A first application, the photo-click cysteine-based material was prepared by photo-click reaction and the stationary phase was employed in the separation of some conventional targets by hydrophilic interaction chromatography.