Kutus, Bence and Dudas, Csilla and Friesen, Sergej and Peintler, Gabor and Palinko, Istvan and Sipos, Pal and Buchner, Richard (2020) Equilibria and Dynamics of Sodium Citrate Aqueous Solutions: The Hydration of Citrate and Formation of the Na(3)Cit(0) Ion Aggregate. JOURNAL OF PHYSICAL CHEMISTRY B, 124 (43). pp. 9604-9614. ISSN 1520-6106, 1520-5207
Full text not available from this repository. (Request a copy)Abstract
Sodium citrate (Na(3)Cit) has a crucial role in many biological and industrial processes. Yet, quantitative information on its hydration and the ion association between Na(+)and Cit(3-) ions in a broad range of salt concentrations is still lacking. In this work, we study both ion association equilibria and relaxation dynamics of sodium citrate solutions by combining potentiometry, spectrophotometry, and dielectric spectroscopy. From photometric and potentiometric measurements, we detect the formation of the NaCit(2-) ion-pair and the neutral Na(3)Cit(0) ion aggregate in a wide range of ionic strengths (0.5-4 M). Due to its remarkable stability, the latter becomes the prevailing species at higher salt concentrations. In the dielectric spectra, we observe the dipolar relaxation of Cit(3-) and NaCit(2-) and two solvent-related processes, associated with the collective rearrangement of the H-bond network (cooperative water mode) and the H-bond flip of water molecules (fast water mode). Unlike numerous other salt solutions, the relaxation time of the cooperative mode scales with the viscosity indicating that the strongly hydrated anion fits well into the water network. That is, the stabilizing effect of anion-solvent interactions on the H-bond network outweighs the destructive impact of the cations as the latter are only present at low concentration, due to strong ion association. In conclusion, the affinity of citrate toward Na+ binding not only governs solution equilibria but also has a strong impact on water dynamics.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | CALCIUM-CITRATE; WATER DYNAMICS; RELAXATION; COMPLEXES; RANK; METABOLISM; POTASSIUM; STABILITY; CHEMISTRY; CONSTANTS; |
| 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: | 08 Mar 2021 11:17 |
| Last Modified: | 08 Mar 2021 11:17 |
| URI: | https://pred.uni-regensburg.de/id/eprint/43504 |
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