Highly enantioseparation in membrane-supported one-dimensional metal–organic framework hollow nanotube array prepared via mussel-inspired chemistry

Abstract

High-enantioselective chiral metal–organic framework (CMOF) nanochannel membranes are of critical importance for chiral enantiomeric separations by taking advantage of their inherent high porosity and intrinsic chirality. However, traditional chiral membranes are still constrained by the permeability-selectivity trade-off, making it challenging to improve both simultaneously. This study described the structure of a new class of membrane-supported one-dimensional MOF hollow nanotube for transport and separation of chiral 1-phenylethanol (PE), utilizing a biomimetic polydopamine (PDA)-mediated counter-diffusion synthesis strategy. The inner cylindrical pore channel surface of polycarbonate track-etched membranes (PCTM) was modified by PDA chemistry to control the nucleation and interfacial growth of CMOF crystals, leading to the development of integrated chromatographic micro-column array membranes PCTM@PDA@Cu2C2D and PCTM@PDA@Cu2C2B with one-dimensional (1D) CMOF hollow nanochannels. Compared to PCTM@PDA@Cu2C2B, it was highlighted that the chiral membrane PCTM@PDA@Cu2C2D possessed the higher loading of Cu2C2D functional layer and more suitable steric chiral microenvironment, thus exhibited more outstanding permeability and selectivity for S-PE enantiomer with an enantiomeric excess value up to 90 % under an optimal guest concentration of 250 ppm at 30 °C for 1 h. The chiral membrane with 1D MOF hollow nanotubes, created by applying a gentle and simple method to introduce CMOF into the surface and pore channels of the substrate membrane, was expected to be utilized for the large-scale production of chiral separation membranes for industrial applications.