Ionic Hydration Behavior Derived from Infrared Spectra in HDO

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2002-05, Vol.106 (21), p.5393-5402
• Main Authors: Stangret, Janusz, Gampe, Teresa
• Format: Article
• Language: English
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp014063v

We have described hydration of ions of different kinds on the basis of infrared spectroscopy and HDO as a probe. Electrolytes with amphiphilic anion have been studied in aqueous solutions of Mg(C2H5SO4)2, NaC2H5SO4, KC2H5SO4, NaC2H5SO3, KC2H5SO3, NaCH3SO4, NaCH3SO3, LiCF3COO, NaCF3COO, KCF3COO, and NaCF3SO3 by means of FTIR spectra of HDO isotopically diluted with H2O. A procedure has been applied that allowed us to remove the contribution of bulk water and thus to separate the spectra of ion-affected HDO. The results and the known literature data treated in the described way were discussed. Ions of different character have been taken into consideration:  mono-, di-, and trivalent, including hydrophobic and amphiphilic ones. Anions and cations appear to have a very different effect on water structure when their polarization power is considered. The energy of affected water H-bonds changes proportionally to the polarization power of anions. On the contrary, cations reveal the zone-type influence. The origin of such hydration behavior and the consequences have been discussed.