Polypeptide-inspired supramolecular assemblies for enantioselective sorption of chiral molecules

Abstract

The separation of racemic mixtures is significant for pharmaceutical production and scientific research, yet it remains challenging to achieve high enantioselectivity. Inspired by the self-assembly of polypeptides with appealing porous structures and high enantioselectivity, we constructed two novel chiral porous assemblies (S-1 and S-2) with one-dimensional coordination polymers derived from tryptophan and phenylalanine, respectively, through multiple intermolecular non-covalent interactions involving hydrogen bonding, C–H⋯π interactions, etc. Gratifyingly, the two resultant supramolecular assemblies can act as solid adsorbents capable of enantioselective capture of chiral small molecules by virtue of their unique chiral cavities and multiple recognition sites, affording high enantiomeric excess (ee) values of 95%. Moreover, such adsorbents can be easily recovered and reused over five times without the loss of enantioselectivity, demonstrating their excellent recyclability. In addition, the assembly S-1 derived from tryptophan possesses more accessible and abundant chiral functionalities in its confined pores, which may enhance its enantioselectivity for chiral molecules. The present work provides an example of regulating the pore structure and chiral microenvironment of bio-mimicking supramolecular assemblies with amino-acid residues to achieve higher selectivity for targeting enantioseparation.