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Electron-transfer reactions in supercritical water
1Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
The Journal of Physical Chemistry. B
|December 18, 2007
Summary
Electron transfer reactions in supercritical water show altered dynamics. Marcus free energy relationships break down at low densities, impacting reaction kinetics predictions.
Area of Science:
- Physical Chemistry
- Computational Chemistry
Background:
- Electron transfer reactions are fundamental in chemistry and biology.
- Understanding solvent effects on reaction dynamics is crucial.
Purpose of the Study:
- To investigate free energies and dynamics of electron transfer reactions in supercritical water.
- To analyze the influence of solvent density on reaction pathways and kinetics.
Main Methods:
- Molecular dynamics (MD) simulations with a two-state electronic description.
- Free energy perturbation (FEP) method to study diabatic electronic curves.
- Analysis of solvent dynamics and transition state theory (TST).
Main Results:
- Diabatic electronic curves are anharmonic and depend on charge distribution.
- Anharmonicity and charge distribution dependence increase with decreasing solvent density.
- Marcus free energy relationship breaks down in low-density supercritical water.
- Deviation from TST predictions increases as water density decreases.
Conclusions:
- Supercritical water significantly alters electron transfer reaction dynamics.
- Traditional models like Marcus theory and TST may fail under extreme solvent conditions.
- Solvent density is a critical factor influencing electron transfer reaction kinetics.
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