Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition properties
Article first published online: 18 DEC 2007
Copyright © 2007 Wiley-Liss, Inc.
Volume 20, Issue 2, pages 151–158, February 2008
How to Cite
Bwambok, D. K., Marwani, H. M., Fernand, V. E., Fakayode, S. O., Lowry, M., Negulescu, I., Strongin, R. M. and Warner, I. M. (2008), Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition properties. Chirality, 20: 151–158. doi: 10.1002/chir.20517
- Issue published online: 18 DEC 2007
- Article first published online: 18 DEC 2007
- Manuscript Accepted: 30 OCT 2007
- Manuscript Received: 14 AUG 2007
- National Science Foundation
- Phillip West Endowment
- chiral ionic liquids;
- chiral selectors;
- chiral recognition
We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L- and D-alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L- and D-alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L- and D-alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal stability (up to 263°C). In addition, the ionic liquids demonstrated enantiomeric recognition ability as evidenced by splitting of racemic Mosher's sodium salt signal using a liquid state 19F nuclear magnetic resonance (NMR) and fluorescence spectroscopy. The L- and D-alanine tert butyl ester chloride resulted in solid salts with nitrate, lactate, and tetrafluoroborate anions. This illustrates the previously observed tunability of ionic liquid synthesis, resulting in ionic liquids of varying properties as a function of varying the anion. Chirality, 2008. © 2007 Wiley-Liss, Inc.