Nanochannels of Covalent Organic Frameworks for Chiral Selective Transmembrane Transport of Amino Acids

Mimicking cellular transport mechanism to make solid-state smart nanochannels has long been of great interest for their diverse applications, but it poses a critical synthetic challenge. Covalent organic frameworks (COFs) are porous crystalline materials with tailor-made nanochannels and hold great potential for ion and molecule transport. We demonstrate here for the first time that 2D COFs possess the necessary merits to be promising solid-state nanochannels for selective transport of amino acids, which are the basis for life. By imine condensations of a C3-symmetric trialdehyde and a mixture of diamines with and without divinyl groups, two vinyl-functionalized 2D COFs are crystallized. Both multivariant COFs afford straight 1D mesoporous channels formed by AA or AB stacking of layered hexagonal networks. After post-modification with chiral β-cyclodextrin (β-CD) via thiol-ene click reactions, the COFs are further fabricated into free-standing mixed matrix membranes (MMMs) that can selectively transport a...