Monolithic capillary electrochromatographic enantioseparation system for dichlorprop based on a novel nanomaterial synthesized by chiral metal organic frameworks and racemic-templated chiral molecular imprinted polymers

Abstract

Dichlorprop (DCPP), a chlorophenoxy herbicide with two enantiomers, shows distinct biological and toxicological properties: R-DCPP is highly effective as a herbicide, while S-DCPP lacks herbicidal activity and is toxic to non-target organisms. Efficient enantioseparation methods for DCPP are crucial for precise herbicide use, reduced agrochemical consumption, and minimized environmental impact. To achieve this purpose, a novel capillary monolithic column (L-His-ZIF-8@CMIP(rac-DCPP/PG-EDMA)@capillary) was fabricated using the nanomaterials synthesized by chiral molecularly imprinted polymers (CMIPs) and chiral metal-organic frameworks (CMOFs, L-His-ZIF-8) as stationary phases. Based on this innovative column, a capillary electrochromatography (CEC) system was established, enabling highly efficient enantioseparation of DCPP, precise chiral purity determination, and accurate quantitative analysis of individual enantiomers in complex real-world samples. During the synthesis of CMIPs, a novel functional monomer, allyl-β-d-Pyrone galactoside (PG), demonstrated unique "pre-chiral recognition" capability towards the racemic template (rac-DCPP) in the CMIP premix. This innovative approach enabled the successful synthesis of chirally selective CMIPs using rac-DCPP as template, rather than conventional single-enantiomer templates, in combination with ethylene dimethacrylate (EDMA) as the cross-linker. This synthesis strategy offers significant advantages, including substantial reduction in production costs and simplified synthesis procedures. To the best of our knowledge, this represents the first reported application of such methodology in CEC worldwide, as confirmed by comprehensive literature review. L-His-ZIF-8@CMIP(rac-DCPP/PG-EDMA)@capillary demonstrates remarkable enantioseparation capabilities through synergistic interactions between its components. Furthermore, the enantioseparation mechanism was systematically investigated through molecular docking and static adsorption experiments, providing fundamental insights into the chiral recognition process. This study establishes a groundbreaking approach for the development of racemic template-based CMIPs and the synthesis of advanced chiral stationary phases, offering significant potential for practical applications in chiral separation science.

Keywords: CMOFs; DCPP; Enantioseparation; Monolithic CEC; Racemic template CMIPs.