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Ion hydration: linking self-diffusion and reorientational motion to water structure
Seishi Shimizu1, Nobuyuki Matubayasi
1York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5DD, UK. seishi.shimizu@york.ac.uk.
Physical Chemistry Chemical Physics : PCCP
|February 9, 2018
Summary
Ions alter water dynamics by influencing its structure. Chaotropic ions stabilize water
Area of Science:
- Physical Chemistry
- Chemical Physics
- Solution Chemistry
Background:
- Ion-water interactions significantly impact water's self-diffusion and relaxation dynamics.
- Existing explanations often link these changes to alterations in water structure around ions.
Purpose of the Study:
- To establish a quantitative link between ion-induced water dynamics and water structure.
- To develop a unified framework for analyzing ion effects on water dynamics.
Main Methods:
- Integration of the extended jump (EJ) model for water reorientation.
- Application of Eyring's transition state theory for water self-diffusion.
- Utilizing preferential solvation theory derived from Kirkwood-Buff (KB) theory.
Main Results:
- A novel scheme is formulated to correlate ion-induced changes in water dynamics with water structure.
- Chaotropic (negatively hydrated) ions stabilize the transition state of water motion.
- Kosmotropic (positively hydrated) ions suppress the formation of the water transition state.
Conclusions:
- Ion effects on water dynamics can be unifiedly explained through KB integrals.
- KB integrals effectively represent the averaged water structures influencing dynamics.
- This provides a new perspective on ion hydration and its impact on water properties.
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