A Chiral COFs Membrane for Enantioselective Amino Acid Separation

Abstract

Incorporating chiral molecules in the covalent organic frameworks (COFs) with uniformly ordered pores results in chiral COFs, which have been highly promising candidates for enantioseparation. Herein, a homochiral COF nanochannel membrane is reported by introducing chiral centers (L-phenylalanine methyl ester) into one of the organic ligands for the enantioseparation of chiral amino acids. The separation results show that the D-isomer is preferentially transported through the porous membrane channel. This composite membrane exhibits excellent selectivity for racemic phenylalanine with the highest enantiomeric excess value of up to 99.4 %. The adsorption and molecular modeling studies substantiate the experiment results by showing higher bonding affinity towards D-isomer over L-isomer. The excellent enantioselective gating performance unveils the porous COF skeleton with chiral selectors and the size-matching synergy for stereoselective interactions with chiral isomers.