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Dynamics around solutes and solute-solvent complexes in mixed solvents
Kyungwon Kwak1, Sungnam Park, M D Fayer
1Department of Chemistry, Stanford University, Stanford CA 94305, USA.
Summary
Solute-solvent dynamics were studied using vibrational spectroscopy. Mixed solvents showed slower dynamics due to solvent composition variations, suggesting altered solvent structure around phenol-OD.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Chemical Dynamics
Background:
- Understanding solute-solvent interactions is crucial for chemical processes.
- Vibrational spectroscopy provides insights into molecular dynamics and solvation structures.
- Phenol-OD in different solvents offers a model system to probe these interactions.
Purpose of the Study:
- To investigate solute-solvent dynamics of phenol-OD in CCl4, mesitylene, and a mixed solvent.
- To observe spectral diffusion and understand its dependence on solvent composition.
- To explore how solvent structure influences molecular dynamics.
Main Methods:
- Ultrafast 2D-IR vibrational echo spectroscopy.
- Infrared (IR) pump-probe experiments.
- Fourier Transform Infrared (FT-IR) spectroscopy.
Main Results:
- Dynamics of free phenol in CCl4 and mixed solvents were similar.
- Dynamics of complexed phenol in mesitylene and mixed solvents were similar.
- Mixed solvents exhibited slower dynamics attributed to solvent composition variations in the first solvation shell, differing from pure solvents where only density variations occur.
Conclusions:
- Solute-solvent dynamics are significantly influenced by solvent composition, especially in mixed solvents.
- The mixed solvent leads to slower dynamics, indicating a longer randomization time for solvent composition variations.
- Experimental results and simulations suggest that the solvent structure around the solute may deviate from the bulk mixed solvent's mole fraction.
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