Chiral separation abilities: Aspartic acid block copolymer-imprinted mesoporous silica

Abstract

Herein we report on the synthesis of chiral mesoporous silica (CMS) that can be used for chiral separation from a racemic mixture of two enantiomers. The CMS with a pore size of 3–5 nm and a high surface area of 725 m 2 g −1 was synthesized by templating chiral block copolymers (CBCs) of polyethylene oxide (PEG) and D/L-aspartic acid (D/L-AspA), [PEO 45-b-(D/L-AspA) 10]. The chiral mesopores were characterized by HRTEM, small angle XRD and BET. The chiral resolution abilities and the chiral separation kinetics of the copolymer-extracted CMS were investigated using a racemic mixture of valine by circular dichroism (CD) and optical polarimetry. The chiral resolution of the CMS was further verified with a racemic mixture of alanine. A chiral selectivity factor of 7.52 was found for the specific enantiomer which is adsorbed preferably. These results allow a new approach towards enantiomeric separation and other enantiomeric applications of novel CMS.