Capillary electrochromatography synergistic enantioseparation system for racemate malic acid based on a novel nanomaterial synthesized by chiral molecularly imprinted polymer and chiral metal-organic framework.

BACKGROUND

Chirality is one of the most fundamental features of nature. In terms of biological activities, pharmacological effects, etc., enantiomers often show great differences among each other. Therefore, it is important to develop highly efficient enantioseparation and analysis methods. Capillary electrochromatography (CEC) is one of the most popular methods in the field of enantioseparation. In the chiral stationary phase of CEC, chiral molecularly imprinted polymers (CMIPs) and chiral metal-organic frameworks (CMOFs) have shown great potential of enantioseparation. However, the enantioseparation performance of CMOFs and CMIPs alone as chiral separation media is less satisfactory.

RESULTS

In this work, a novel nanomaterial synthesized by CMOFs and CMIPs was used as stationary phase in CEC synergistic enantioseparation system and the relevant reports have not been internationally found by authors. As a proof-of-concept demonstration, a coated capillary column was prepared by a one-step method using l-malic acid (template), [Cu(D-Cam)Dabco] (Cu-MOF) and dopamine (functional monomer/cross-linking agent), which greatly simplified the modification process of the capillary columns. Compared with Cu-MOF and CMIP alone, the CEC synergistic enantioseparation system based on Cu-MOF@MIP has significantly better enantioseparation performance of malic acid enantiomers (resolution: 1.03/0.58 → 4.22), and there is also a satisfactory performance in the quantitative analysis in real samples. Finally, through molecular docking and adsorption experiments, it was systematically proved that Cu-MOF@MIP had a significantly stronger binding ability for l-malic acid than d-malic acid.

SIGNIFICANCE

Cu-MOF with chiral recognition ability have synergize with CMIPs to greatly improve the chiral selectivity of Cu-MOF@MIP, which is firstly used for the construction of the CEC chiral separation system. This pioneering synergistic chiral separation system creates a potential direction for efficient enantioseparation. Considering the diversity of CMOFs and CMIPs, the stationary phases hold great promise in chiral separation science.