The homochiral compounds play an important role in human health and pharmaceutical industry.Currently,the chromatographic enantioseparation has become one of the most effective and practical approach to obtain pure enantiomers.Herein,the exploration of advanced materials,using as chromatographic chiral stationary phases for racemic separation,has attracted great attention.Thanks to their high enantioselectivity and controllable synthesis,the emerging chiral metal-organic frameworks (CMOFs)have been widely studied as the stationary phase in chromatographic technology.In this review,we will summarize the principles of synthetic strategies and mechanism of chiral microenvironment.In particular,the recent progress and research hotspot of CMOFs regarding as the chiral stationary phases in gas chromatography (GC),high-performance liquid chromatography (HPLC),and capillary electrochromatography (CEC),are elucidated systematically according to the published work.Last but not the least,we also highlight the challenges and perspectives of rational design of CMOFs,as well as their corresponding racemic separation.We envision that the review will provide a further understanding of CMOFs and facilitate the development of chromatographic enantioselective applications.
Researchers engrossed in enantioseparation keep seeking for versatile chiral separation selectors.This work proposes a concept of quasi-dual-chiral-channel(QDCC)enantioseparation platform,where the surface sequentially grafted quinine(QN)and functional cyclodextrin(CD)can imitate two independent chiral channels without mutual interference to achieve wide spectrum chiral resolution.Chiral separation results combined with molecular docking simulation indicates that the different interaction mode of QN and functional CD layer renders QDCC the wide separation capability.This work provides a valuable insight into the rational design of versatile enantioseparation materials.
In this work, a series of chiral phenethylamine synergistic tricarboxylic acid modified β-cyclodextrin bonded stationary phase for high performance liquid chromatography(HPLC) were synthesized via a simple one-pot synthesis approach. Various racemates(aryl alcohols, flavanones, triazoles, benzoin, etc.) were well separated on the tricarboxylic acid modified chiral stationary phases in both normal and reversed modes with good reproducibility and stability, and the influence of mobile phase composition on resolution(R_(s)) were deeply investigated. The RSD values of Rsfor repeatability and column-to-column were below 1.28% and 3.05%, respectively. Hence, the fabrication of tricarboxylic acid modified chiral stationary phase(CSPs) is a new efficient strategy to improve the application of β-cyclodextrin as CSPs in the field of chromatography.
Chiral metal-organic frameworks(CMOFs)with enantiomeric subunits have been employed in chiral chemistry.In this study,a CMOF formed from 6-methoxyl-(8S,9R)-cinchonan-9-ol-3-carboxylic acid(HQA)and ZnCl_(2),{(HQA)(ZnCl_(2))(2.5H_(2)O)}n,was constructed as a chiral stationary phase(CSP)via an in situ fabrication approach and used for chiral amino acid and drug analyses for the first time.The{(HQA)(ZnCl_(2))(2.5H_(2)O)}n nanocrystal and the corresponding chiral stationary phase were systematically characterised using a series of analytical techniques including scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,circular dichroism,X-ray photoelectron spectroscopy,thermogravimetric analysis,and Brunauer-Emmett-Teller surface area measurements.In opentubular capillary electrochromatography(CEC),the novel chiral column exhibited strong and broad enantioselectivity toward a variety of chiral analytes,including 19 racemic dansyl amino acids and several model chiral drugs(both acidic and basic).The chiral CEC conditions were optimised,and the enantioseparation mechanisms are discussed.This study not only introduces a new high-efficiency member of the MOF-type CSP family but also demonstrates the potential of improving the enantioselectivities of traditional chiral recognition reagents by fully using the inherent characteristics of porous organic frameworks.
Xiangtai ZhengQi ZhangQianjie MaXinyu LiLiang ZhaoXiaodong Sun
