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pH‐dependent cyclodextrin capillary electrophoresis resolution of atropisomers
Author(s) -
Zerbinati Orfeo,
Trotta Francesco
Publication year - 2003
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200305518
Subject(s) - capillary electrophoresis , cyclodextrin , chromatography , atropisomer , chemistry , resolution (logic) , electrophoresis , capillary action , materials science , stereochemistry , computer science , artificial intelligence , composite material
Five noncommercial and four commercially available cyclodextrin (CD) derivatives were tested as chiral auxiliaries for the capillary electrophoretic (CE) resolution of racemic 1,1’‐bi‐(2‐naphthol) (BN), 1,1’‐binaphthyl‐2,2’‐diyl hydrogenphosphate (BNHP), and 1,1’‐binaphthyl‐2,2’‐diamine (BNA) at pH 4.0, 6.5, and 8.6. The noncommercial CDs were ethyloxycarbonyl‐γ‐CD (ethylcarbonate‐γ‐CD), dimethylamino ethyloxycarbonyl‐β‐CD, a mercaptosuccinic acid derivative of β‐CD, a maleic acid derivative of β‐CD and heptakis(6‐deoxy‐6‐amino)‐β‐CD derivative with one amino group on the C‐6 carbon of each glucose unit. Except for the latter, the remaining derivatives were synthesized for this work. Also commercially available methyl‐β‐CD, hydroxypropyl‐β‐CD and the native β‐ and γ‐CDs were examined. Among the nine CDs tested, the maleic acid derivative of β‐CD gave the most interesting performances, since it resolved the atropisomers of BNA and BNHP in the same electrophoretic run at pH 4.0. It resolved the BNA racemate also at pH 6.5. Both the negatively charged CD tested were found to resolve anionic BNHP enantiomers, while positively charged CDs did not with cationic BNA. Several of the CDs investigated in this work were found to resolve the BNHP racemate, although at nonoptimal concentration. None of the experimented CDs was found to resolve the electrically neutral BN atropisomers pair at the three pHs considered, while some among these nine, experimented in a previous work, did so at higher pH.