Contribution to the Proceedings of the 22nd International Symposium on Chirality [ISCD 22]
Regular Article/Contribution to the Proceedings of the 22nd International Symposium on Chirality [ISCD 22]
Experimental and theoretical studies of vacuum-ultraviolet electronic circular dichroism of hydroxy acids in aqueous solution†
Article first published online: 28 APR 2011
Copyright © 2011 Wiley Periodicals, Inc.
Special Issue: Proceedings from the 22nd International Symposium on Chirality, Sapporo, Japan, 2010
Volume 23, Issue 1E, pages E52–E58, 2011
How to Cite
Fukuyama, T., Matsuo, K. and Gekko, K. (2011), Experimental and theoretical studies of vacuum-ultraviolet electronic circular dichroism of hydroxy acids in aqueous solution. Chirality, 23: E52–E58. doi: 10.1002/chir.20962
- Issue published online: 24 OCT 2011
- Article first published online: 28 APR 2011
- Manuscript Accepted: 24 FEB 2011
- Manuscript Received: 30 OCT 2010
Choose one or more boxes to highlight terms.
- assignment of electronic circular dichroism;
- L-lactic acids;
- time-dependent density functional theory;
- hydrated structures;
- synchrotron-radiation spectroscopy
The electronic circular dichroism (ECD) spectra of three L-hydroxy acids (L-lactic acid, (+)-(S)-2-hydroxy-3-methylbutyric acid, and (−)-(S)-2-hydroxyisocaproic acid) were measured down to 160 nm in aqueous solution using a vacuum-ultraviolet ECD spectrophotometer. To assign the two positive peaks around 210 and 175 nm and the one negative peak around 190 nm in the observed spectra, the ECD spectrum of L-lactic acid was calculated using time-dependent density functional theory (DFT) for the optimized structures by DFT and a continuum model. The observed ECD spectrum was successfully reproduced as the average spectrum for four optimized structures with seven water molecules that localized around the COO− and OH groups of L-lactic acid. The positive peak around 210 nm and the negative peak around 185 nm in the calculated spectrum were attributable to the nπ* transition of the carboxyl group, with the latter peak also being influenced by the ππ* transition of the carboxyl group; however, the positive peak around 165 nm involved unassignable higher energy transitions. The comparison of the calculated ECD spectra for L-lactic acid and L-alanine revealed that the network with loose hydrogen bonding around the COO− and OH groups is responsible for the flexible conformation of hydroxy acids and complicated side-chain dependence of ECD spectra relative to amino acids. Chirality, 2011. © 2011 Wiley Periodicals, Inc.