Precise sieving of chiral molecules by a crosslinked cyclodextrin-cellulose nanofiber composite membrane

Polymeric enantioselective membranes have shown great potential for efficient chiral separations, but it is difficult to precisely tailor their porous structures at the molecular level to achieve desirable separation properties. In this work, cyclodextrins (CDs) with their inherent truncated shape homochiral pores were directly utilized as building blocks to fabricate a microporous polyester layer superposed on a cellulose nanofiber (CNF) layer through a facile interfacial polymerization method. The as-obtained trimesoyl chloride (TMC) crosslinked β-CD-TMC-CNF composite membrane exhibited ultimate enantioselectivity (i.e., an enantiomeric excess (ee) of 100%) toward 2-phenyl-1-propanol and the highest flux of 4.08 × 10−3 mol m−2 h−1 compared with the membranes made with α-CD and γ-CD. This enantioselective composite membrane with intrinsic microporosity is promising for further development for high-performance practical chiral separation.