ESI-MS investigation of solvent effects on the chiral recognition capacity of tartar emetic towards neutral side-chain amino acids.
The effect of solvent systems on previously-reported ESI-MS based proton-assisted enantioselective molecular recognition phenomena of tartar emetic, L-antimony(III)-tartrate, was evaluated. This was achieved by carrying out a series of competitive binding experiments using chiral selectors, bis(sodium) D- and -L-antimony(III)-tartrates with chiral selectands, neutral side-chain amino acid enantiomeric isotopomers of alanine (Ala), valine (Val), leucine (Leu) and phenylalanine (Phe), in three different solvent systems, ACN/H(2)O (75/25 v/v), H(2)O (100%) and H(2)O/MeOH (25/75 v/v). Observations from these experiments suggest that the effect of solvent systems on previously reported proton-assisted chiral recognition capacity of D,L-antimony(III)-tartrates is small, but not negligible. It was observed that an ACN/H(2)O (75/25 v/v) solvent system facilitates and enhances the chiral discrimination capacity of protonated {[D,L-Sb(2)-tar(2)][H]}(-) ionic species. Further, amino acid enantiomers showed a general trend of increasing selectivity order, Val ≤ Ala < Leu ≈ Phe towards the protonated {[D,L-Sb(2)-tar(2)][H]}(-) ionic species which was independent of the solvent system employed. The lack of enantioselective binding for {[D,L-Sb(2)-tar(2)]}(2-) ionic species was consistently recorded in respective mass spectra from all performed experiments, which suggests that ESI-friendly solvent systems have no effect and do not influence this phenomenon.
Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, Texas, USA.
Aruna B
AB
Wijeratne
Samuel H
SH
Yang
Jose
J
Gracia
Daniel W
DW
Armstrong
Kevin A
KA
Schug
D021542:Amino Acids, Neutral / Q000737:chemistry*; D000966:Antimony Potassium Tartrate / Q000737:chemistry*; D001667:Binding, Competitive; D015394:Molecular Structure; D011522:Protons; D012997:Solvents; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism; D013644:Tartrates / Q000138:chemical synthesis / Q000737:chemistry
D021542:Amino Acids, Neutral; D011522:Protons; D012997:Solvents; D013644:Tartrates; D000966:Antimony Potassium Tartrate