Chiral ligand exchange chromatograph

Based on preliminary results from Helfferich130, further developments by Davankov and co-workers5 131 133 turned the principle of chelation into a powerful chiral chromatographic method by the introduction of chiral-complex-forming synlhetie resins. The technique is based on the reversible chelate complex formation of the chiral selector and the selectand (analyte) molecules with transient metal cations. The technical term is chiral ligand exchange chromatography (CLEC) reliable and complete LC separation of enantiomers of free a-amino acids and other classes of chiral compounds was made as early as 1968 131. 

Another molecular rect nition force is the metal-complex formation realized in chiral ligand-exchange chromatography (CLEC). The technique was first proposed by Helf-ferich ]400] and was turned into a powerful chromatographic technique by Davankov and co-workers [8,401 j. This technique is based on a reversible chelate-complex forma-... 

In view of the importance of chiral resolution and the efficiency of liquid chromatographic methods, attempts are made to explain the art of chiral resolution by means of liquid chromatography. This book consists of an introduction followed by Chapters 2 to 8, which discuss resolution chiral stationary phases based on polysaccharides, cyclodextrins, macrocyclic glyco-peptide antibiotics, Pirkle types, proteins, ligand exchangers, and crown ethers. The applications of other miscellaneous types of CSP are covered in Chapter 9. However, the use of chiral mobile phase additives in the separation of enantiomers is discussed in Chapter 10. 

Such cases can be encountered in the case of thin-layer chromatographic separation of amino acids, using copper complexes of long chain amino acids as chiral additives via a ligand exchange approach. The copper complexes of alkyl amino acid chiral additives are so strongly adsorbed on the RP stationary phase that they act as a chiral stationary phase [154-156]. 

Kurganov A (2001) Chiral chromatographic separations based on ligand exchange. Journal of Chromatography A 906 51-71. 

Recent experimental results have confirmed the principle of chiral interaction (three-point rule) postulated as early as 19S2 by Dalgliesh (56). Additionally, the results prove that the separation models developed for ligand exchange by high-performance liquid chromatography (16,156,157) are also valid for T1.C the diastereomeric complexes formed with the metal ion (e.g., Cu ) and the chiral adsorbent have different stabilities for the different antipodes, and thus chromatographic separation is achieved. 

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