Amino acid modified carbon nanotubes with optimal pore size for chiral separation

Precisely controlling pore size of porous materials is of great importance for chiral separation, but a great challenge in practical applications. In contrast, the molecular dynamics (MD) simulation can be quite a convenient way to determine the effect of the pore dimension on the chiral resolution performances and thus to define the optimal pore size. In this work, inner-wall functionalised carbon nanotubes (CNTs) were used as porous materials and D- and L-phenylalanine were selected as chiral probes. The enantioseparation behaviour was investigated via varying the pore diameter of CNTs, controlling the grafting amount of chiral selectors and tuning the spacer length. Results show that varying the pore size has a significant effect on the enantioselectivity. Additionally, the effect of the introduction of varying the grafting ratio and tuning the spacer length on the chiral separation performance was also examined in this work. It was found that varying the grafting ratio, especially the spacer length between substrates and selectors, could also be one of the most effective alternatives to improving enantioselectivity. Our findings can provide a guidance for the practical applications in the chiral separation.