Elucidation of chiral Recognition mechanism of alpha-amino acids using ligand exchange high performance liquid chromatography

• Published in: Journal of the Brazilian Chemical Society Vol. 18; no. 7; pp. 1367 - 1373
• Main Authors: Senra, Jaqueline D., Malta, Luiz Fernando B., Ceva-Antunes, Patricia M. N., Corrêa, Rodrigo J., Antunes, O. A. C.
• Format: Journal Article
• Language: English
• Published: Sociedade Brasileira de Química 2007
• Subjects: CHEMISTRY, MULTIDISCIPLINARY; L-phenylalanine; ligand exchange chromatography; fourier self-deconvolution; alpha-amino acids; ab initio molecular orbital calculations
• ISSN: 0103-5053; 1678-4790
• DOI: 10.1590/S0103-50532007000700012

Ligand exchange HPLC technique was applied to resolve chiral separation of aliphatic side chain aminoacid racemates. Chiral selector was copper L-phenylalaninate (II) and the results showed the elution of D enantiomer followed by L form. Considering the 3-point interaction concept, a mechanism of chiral recognition was proposed, in which no change of configuration would follow the formation of pseudo-homochiral and heterochiral complexes. To prove the reliability of this mechanism, the trans configuration of homochiral complex had to be more stable than the cis form, which was confirmed by DFT-B3LYP calculation in gas phase. The infrared frequencies were also calculated and the comparison with the subtracted and deconvoluted spectrum of the in-solution complex also pointed to the presence of the trans diasteroisomer.