Deuterium isotope effects observed during competitive binding chiral recognition electrospray ionization--mass spectrometry of cinchona alkaloid-based systems.
Deuterium isotope effects are reported for binding between tert-butylcarbamoyl-quinine/quinidine chiral selectors and isotopomeric quasienantiomers of N-(3,5-dinitrobenzoyl)leucine measured using electrospray ionization-mass spectrometry (ESI-MS) and competitive binding. Evaluation of mixtures of each selector with one labeled and one unlabeled enantiomeric selectand of identical configuration showed a significant difference in measured ion abundances of diastereomeric complexes between the selector and each selectand. It was found that in some cases, the complex containing the nondeuterated selectand was 15% more abundant than its deuterated counterpart. On the basis of an assessment of solution- and gas-phase isotope effects reported in the literature, a series of control experiments were performed to study the origin of the effects. On the basis of these measurements, our preliminary conclusion is that the differing gas-phase physicochemical nature of the deuterated versus nondeuterated selectand represents the strongest contribution to the observed effect in this chiral molecular recognition system.
Schug
Kevin A
KA
University of Vienna, Department of Analytical Chemistry and Food Chemistry Währingerstrasse 38, A-1090 Vienna, Austria. kschug@uta.edu
Maier
Norbert M
NM
Lindner
Wolfgang
W
D001667:Binding, Competitive; D002929:Cinchona / Q000737:chemistry; D002930:Cinchona Alkaloids / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D007553:Isotope Labeling; D015394:Molecular Structure; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism
D002930:Cinchona Alkaloids; D003903:Deuterium