Hunger, Johannes and Niedermayer, Stefan and Buchner, Richard and Hefter, Glenn (2010) Are Nanoscale Ion Aggregates Present in Aqueous Solutions of Guanidinium Salts? JOURNAL OF PHYSICAL CHEMISTRY B, 114 (43). pp. 13617-13627. ISSN 1520-6106,
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A detailed investigation using broadband dielectric relaxation spectroscopy (DRS) has been made of the aqueous solutions of guanidinium chloride and carbonate, GdmCl(aq) and Gdm(2)CO(3)(aq), at 25 degrees C. The spectra indicate that Gdm(+) ions, C(NH2)(3)(+), do not bind strongly to water nor are they hydrophobically hydrated; rather they appear to have a most unusual ability to dissolve in water without altering its dynamics. Although DRS is particularly sensitive to the presence of ion pairs, only weak ion pairing was detected in Gdm(2)CO(3)(aq) solutions and none at all in GdmCl(aq). Surprisingly, no evidence was found for the existence of the higher order homo- and heteroionic nanoscale aggregates that have been identified in recent years by Mason and co-workers using molecular dynamics simulations and neutron diffraction. Possible reasons for this discrepancy are discussed. The present DR spectra and other solution properties of GdmCl(aq) and Gdm(2)CO(3)(aq), such as apparent molar volumes and electrical conductivities, are shown to have strong similarities to those of the corresponding Na+ salts. However, such solutions also differ remarkably from their Na+ analogues (and all other simple electrolytes in aqueous solution) in that their average water relaxation times correlate strongly with their bulk viscosities. The biological implications of the present results are briefly discussed.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | DIELECTRIC-RELAXATION SPECTROSCOPY; ELECTROLYTE-SOLUTIONS; CONCENTRATED-SOLUTIONS; PROTEIN DENATURATION; SOLVENT RELAXATION; CHLORIDE SOLUTIONS; SODIUM-CHLORIDE; 298.15 K; HYDRATION; ASSOCIATION; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > PD Dr. Richard Buchner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 07 Jul 2020 06:01 |
| Last Modified: | 07 Jul 2020 06:01 |
| URI: | https://pred.uni-regensburg.de/id/eprint/23892 |
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