Influence of Kosmotrope and Chaotrope Salts on Water Structural Relaxation

The structural relaxation in water solutions of kosmotrope (structure maker) and chaotrope (structure breaker) salts, namely sodium chloride, potassium chloride, and cesium chloride, were studied through quasielastic neutron scattering measurements. We found that the collective dynamics relaxation t...

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Bibliographic Details
Published in:The journal of physical chemistry letters 2020-11, Vol.11 (21), p.8970-8975
Main Authors: Luo, Peng, Zhai, Yanqin, Senses, Erkan, Mamontov, Eugene, Xu, Guangyong, Z, Y, Faraone, Antonio
Format: Article
Language:English
Subjects:
INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
Ions
Noncovalent interactions
Physical Insights into Materials and Molecular Properties
Salts
Solution chemistry
Viscosity
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Summary:The structural relaxation in water solutions of kosmotrope (structure maker) and chaotrope (structure breaker) salts, namely sodium chloride, potassium chloride, and cesium chloride, were studied through quasielastic neutron scattering measurements. We found that the collective dynamics relaxation time at the structure factor peak obtained using heavy water solutions shows a distinctively different behavior in the kosmotrope as opposed to the chaotrope solutions, increasing with the salt concentration in the former and decreasing in the latter. In both cases the trends are proportional to the concentration dependence of the relative viscosity of the solutions. These results indicate that kosmotropes and chaotropes influence the solution’s viscosity by impacting in opposite ways the hydrogen bond network of water, strengthening it in one case and softening it in the other.
ISSN:1948-7185
1948-7185
DOI:10.1021/acs.jpclett.0c02619