Conformations and hydration of halopropionic acids studied by molecular dynamics and Raman optical activity.

[Display omitted] • Traces of water in the sample can change the signs of ROA bands. • This was explained by supramolecular organization of studied acids around water and changed acidobasic equilibria. • Raman and ROA spectra of halogenated compounds were interpreted using MD/DFT. • Esterification of the halo acids caused significant changes in vibrational spectra. Chiral 2-halopropionic acids and their derivatives were synthesized and their properties studied computationally using Raman and Raman optical activity (ROA) spectroscopy. For neat acids present as liquids small amount of water led to significant changes in the spectra, resulting even to flipping of some ROA band signs. We find this interesting for the role water plays in interpretation of vibrational optical activity spectra of biomolecules. Analysis of the results shows that when the water is present, it can change ROA band signs due to the changes in acidobasic equilibrium. Corresponding esters without acidic hydrogens do not exhibit such effects. [ABSTRACT FROM AUTHOR]