Chiral separation of β-cyclodextrin modified graphene oxide membranes with a complete enantioseparation performance

The separation of racemates remains a great challenge as they are enantiomers with similar chemical structures and physicochemical properties in achiral environments. Recently, graphene oxide (GO) based membranes modified with various chiral selectors had been proved to allow for both high permeation flux and enantioselectivity. Herein, mono(6-amino-6-deoxy)-beta-cyclodextrin (β-CD) was selected to serve as chiral selector in GO-based membranes for separating racemates, since it potentially forms specific inclusion complexes with guests. Results show that β-CD displays a much stronger enantioselective affinity toward l-enantiomer than d-enantiomer, so that such β-CD modified GO membrane (β-CD-GOM) exhibits a retarded transport mechanism, having exceptional enantioselectivities with the enantiomeric excess value of nearly 100%. Moreover, β-CD-GOMs are 1-2 orders of magnitude higher in flux than traditional enantioseparation membranes. These findings demonstrate that β-CD-GOMs could provide new opportunities for improving enantioseparation performances with both high permeability and high permselectivity and for the large-scale production of various enantiomers.