Cellulose phenylcarbamate-derived hybrid bead-type chiral packing materials for efficient chiral recognition

For efficient enantioseparation, eight organic–inorganic hybrid bead-type chiral packing materials (CPMs) with high organic contents have been developed using cellulose tris(3,5-dimethylphenylcarbamates) bearing small amount of 3-(triethoxysilyl)propyl groups and tetraethyl orthosilicate by a modified Stöber process in the basic condition. The hybrid beads could be formed more efficiently in the basic condition without using surfactant, compared to that in the acidic condition. The preparation conditions, including type and amount of catalyst, amount of water and temperature, significantly affected the organic contents and morphology of the hybrid CPMs. Their chiral recognition properties were then examined by high-performance liquid chromatography. The obtained hybrid CPMs with a higher organic content possessed better enantioseparation ability than the traditional CPMs and previous analogue derived from the acidic condition. For some racemates, the hybrid CPMs exhibited even higher enantioselectivity than the commercial Chiralpak IB N, which is one of the most powerful immobilized-type CPMs and prepared from cellulose tris(3,5-dimethylphenylcarbamate).