Chiral Post-Modification of UiO-66-NH₂ on Gas Chromatography Chiral Separation

As enantiomers can have different pharmacological and toxicological impacts even though they have the analogous chemical composition, efficient chiral separation is crucial. Chromatography is one of the primary methods for separating enantiomers, and the key to chromatographic separation lies in the chiral stationary phase (CSP). Chiral porous materials have emerged as innovative chiral stationary phases and garnered extensive attention. Zr based MOF materials, have been regarded as one of the most stable metal-organic framework (MOF) materials. In this paper, after grafting with L-proline, UiO-66 was used for the first time for chiral gas chromatography separation. The newly developed CSP provided high resolution for xylenes within only 2-3 min. For substances like linalool, α-pinene, and xylenes, the UiO-66-NH₂-L-Pro-coated capillary column acquired bas3ic resolution and showed outstanding enantiomeric and positional isomer isolation. Comprehensive characterizations, including SEM, XRD, FT-IR, TGA, N₂ adsorption-desorption isotherms, CD spectra, and XPS, were conducted to analyze the material stucture and chiral recognition mechanism. The chiral separation relies on transient diastereomeric complexes formed between L-proline and enantiomers, stabilized by hydrogen bonding, intermolecular forces, and steric constraints within UiO-66's micropores. These interactions enforce enantioselective discrimination via the pore's stereochemical filtering, enabling chiral resolution. This study is expected to provide significant value for both chromatographic chiral separation and large-scale chiral substance separation.