Performance of brush-type HPLC chiral stationary phases with tertiary amide in the connecting tether.
The replacement of the N-H hydrogen of the secondary amide-tethered Pirkle-concept N-(3,5-dinitrobenzoyl)-L-leucine derived chiral stationary phase with various pi-basic or aliphatic groups improved the chiral discrimination ability of new chiral stationary phases, based on the leucine- or alanine-derived chiral selector, for the enantiomers of various racemic neutral analytes with amide functional groups. Retention times decreased while separation and resolution factors increased, thus proving the role of pi-donor aromatic unit as an electron-rich shield in the front of a silica surface. In general, chiral stationary phase (CSP) 5 with the 3,5-dimethylphenyl unit showed best performance, while CSP 3, with phenyl unit, and CSP 7, with 1-naphthyl unit in the tertiary amide connecting tether, were less efficient.
Forjan
Davorka Moslavac
DM
Laboratory for Stereoselective Catalysis and Biocatalysis, Ruder Bosković Institute, P.O. Box 180, Bijenicka Cesta 54, HR-10002 Zagreb, Croatia.
Kontrec
Darko
D
Vinković
Vladimir
V
D000577:Amides / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D015394:Molecular Structure; D013237:Stereoisomerism
D000577:Amides