CE, NMR and electrospray ionization mass-spectrometry studies of chiral recognition of pheniramine and structural analogues with cyclodextrins

In a previous study we observed the opposite migration order of the enantiomers of (±)-chlorpheniramine using native and derivatized cyclodextrins (CDs) as chiral selectors [1]. The study using compounds possessing a similar structure (pheniramine, brompheniramine, carbinoxamine, doxylamine) were performed in order to estimate the role of substituents on the chiral recognition of pheniramines and structurally related compounds by the CD-hosts. NMR spectroscopy and electrospray ionization mass-spectrometry (ESI-MS) were applied together with CE in order to obtain more detailed information on the chiral recognition mechanism. Additionally, the effect of the buffer pH was studied in the both CE and NMR. The opposite migration order of the enantiomers observed for (±)-chlorpheniramine were also found for pheniramine and brompheniramine. Additionally, the substituent in the para position of the phenyl moiety plays a critical role in the chiral recognition of pheniramines with the CDs.