title: Molecular association of betaine and betaine hydrochloride in aqueous solutions--a study by Raman spectroscopy.
abstract: Raman vibrational spectroscopy, at 298 K, has been used to study the hydration of betaine hydrochloride and betaine in the concentration range 0.5-2 M. The observed changes in the internal vibrations of the solutes, namely, in the C=O, COO- and C-H stretchings, and in the components of the O-H stretching band are consonant with anionic water-betaine and betaine hydrochloride dimeric species involving simultaneously hydrogen-bonding between two solute and water molecules. In both cases, betaine hydrochloride and 'zwitterionic' betaine behave like structure-makers promoting a larger association in the 'bulk' liquid water.
authors.affiliation: Department of Chemistry, University of Coimbra, 3000, Coimbra, Portugal. acosta@ci.uc.pt
authors.forename: A
authors.initials: A
authors.lastname: Amorim da Costa
authors.forename: J E
authors.initials: JE
authors.lastname: Leite
mesh_terms: D001622:Betaine / Q000737:chemistry*; D019281:Dimerization; D006860:Hydrogen Bonding; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D012996:Solutions; D013059:Spectrum Analysis, Raman; D014867:Water
chemical_list: D046911:Macromolecular Substances; D012996:Solutions; D014867:Water; D001622:Betaine