trans-(1R,2R)-diaminocyclohexane-functionalized mesoporous organosilica spheres as chiral stationary phase

The bifunctionalized mesoporous organosilica spheres with trans-(1R,2R)-diaminocyclohexane (DACH) in the pore were synthesized and their application as chiral stationary phase in high-performance liquid chromatography (HPLC) was demonstrated. Bifunctionalized mesoporous organosilica spheres with narrow particle size distribution of 5-7 mu m were prepared by the co-condensation of N-[3-(triethoxysilyl)propyl]-trans(1R,2R)-diaminocyclohexane (M(propyl)) with 1,2-bis(trimethoxysilyl)ethane (BTME) in basic medium using octadecyltrimethyl ammonium chloride (C(18)TAC1) as structural directing agent and ethanol as co-solvent. The morphologies of the bifunctionalized mesoporous organosilicas were sensitive to the molar fraction of M(propyl). At higher M(propyl)/BTME molar ratio, the bifunctionalized organosilica spheres with ordered mesoporous structure can be formed in a wide range of synthetic conditions. When the molar percent of M(propyl)/(M(propyl)/BTME) is less than 20, the formation of spheres could be hardly observed. The structural order of the materials mainly depends on the base concentration and Mpropyi/BTME molar ratio in the initial sol mixture. A column packed with the bifunctionalized mesoporous organosilica spheres exhibits higher selectivity and resolution for racemic amino acids than that packed with DACH-SiO(2) prepared by conventional post-synthesis grafting method. (c) 2007 Elsevier B.V. All rights reserved.