Raman and FTIR spectroscopic study on water structural changes in aqueous solutions of amino acids and related compounds

Structural changes of water in aqueous solutions of glycine, alanine, ammonia, amines (methyl-, ethyl-, propyl-, and n-butylamine), carboxylic acids (formic, acetic, propionic, and n-butyric acid), KF and 1-hexansulphonic acid sodium salt have been analysed using FTIR and Raman difference spectroscopy. Isotropic and anisotropic Raman spectra, as well as the rhospectra, have been calculated. The OH stretching region of the amino acid difference spectra shows changes in defined frequency regions which can be attributed to electrostatic and hydrophobic interactions as well as to hydrogen bonding. Point charges affect the symmetry of the water molecules, while for hydrophobic interaction no symmetry changes in the water molecules are observed. (C) 1997 Elsevier Science B.V.