Novel chiral core–shell silica microspheres with trans-(1R,2R)-diaminocyclohexane bridged in the mesoporous shell: Synthesis, characterization and application in high performance liquid chromatography

Novel chiral core–shell silica microspheres with trans-(1R,2R)-diaminocyclohexane (DACH) moiety bridged in the mesoporous shell were synthesized using layer-by-layer method. The chiral mesoporous shell around the nonporous silica core was formed by the co-condensation of N,N′-bis-[(triethoxysilyl)propyl]-trans-(1R,2R)-bis-(ureido)-cyclohexane (DACH-BS) and tetraethoxysilane (TEOS) using octadecyltrimethylammonium chloride (C18TMACl) and triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer (P123) as the templates. The functionalized core–shell silica microspheres were characterized and tested as chiral stationary phases for high performance liquid chromatography (HPLC). R/S-1,1′-bi-2,2′-naphthol, R/S-6,6′-dibromo-1,1′-bi-2-naphthol and R/S-1,1′-bi-2,2′-phenanthrol were enantioseparated rapidly on the column packed with the DACH core–shell silica particles. Moreover, the column packed with core–shell particles exhibited better performance than the column packed with the DACH functionalized periodic mesoporous organosilicas.