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Excess protons in mesoscopic water-acetone nanoclusters.
Rocío Semino1, Jordi Martí, Elvira Guàrdia
1Departamento de Química Inorgánica Analítica y Química-Física e INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, 1428 Buenos Aires, Argentina.
The Journal of Chemical Physics
|November 28, 2012
Summary
Proton solvation in binary polar clusters depends on concentration fluctuations. The proton stays in water-rich regions, with transfer times increasing significantly with more acetone.
Area of Science:
- Physical Chemistry
- Computational Chemistry
- Chemical Physics
Background:
- Proton solvation in bulk water is well-understood.
- Mesoscopic systems exhibit unique properties due to concentration fluctuations.
- Understanding proton behavior in mixed solvent clusters is crucial for various chemical processes.
Purpose of the Study:
- To investigate the equilibrium and dynamical characteristics of excess proton solvation.
- To examine the influence of concentration fluctuations on proton solvation in binary polar clusters.
- To elucidate the role of acetone concentration on proton transfer dynamics.
Main Methods:
- Molecular dynamics (MD) simulations were employed.
- Simulations focused on mesoscopic binary polar clusters (50 water molecules and varying acetone concentrations).
- Analysis included equilibrium and dynamical properties of proton solvation and transfer.
Main Results:
- Proton solvation is governed by concentration fluctuations, deviating from macroscopic behavior.
- At low acetone concentrations, protons localize in acetone-deprived aqueous regions.
- At higher acetone concentrations, protons remain in aqueous domains, with transfer times significantly increasing (nanosecond scale for n=25).
Conclusions:
- Cluster morphology and proton solvation are intrinsically linked to concentration fluctuations.
- Acetone concentration modulates proton transfer dynamics, leading to significant retardations.
- Proton transfer mechanisms involve water/acetone exchange and diffusive motions within aqueous domains.
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