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Published on: June 8, 2022
Composition-mediated intermolecular interaction transition and vibrational reorganization in n-hexane-ethanol binary
Jiacheng Ma1, Guannan Qu2, Guangshuo Wu1
1School of Science, Changchun University of Science and Technology, Changchun 130022, China.
Summary
Mixing ethanol and n-hexane reveals composition-dependent molecular changes. Raman spectroscopy and DFT calculations show vibrational shifts and structural reorganization driven by intermolecular interactions like hydrogen bonding.
Area of Science:
- Physical Chemistry
- Spectroscopy
- Computational Chemistry
Background:
- Binary liquid mixtures are crucial for understanding molecular interactions.
- Ethanol-n-hexane mixtures offer a model system for studying polar-nonpolar interactions.
- Composition-dependent molecular behavior influences macroscopic properties.
Purpose of the Study:
- To investigate the molecular origin of vibrational and structural changes in n-hexane-ethanol mixtures.
- To correlate spectral shifts with intermolecular interactions across varying compositions.
- To elucidate the role of hydrogen bonding and other interactions in mixture organization.
Main Methods:
- Raman spectroscopy was used to analyze vibrational spectra.
- Density Functional Theory (DFT) calculations were employed for theoretical analysis.
- Molecular Dynamics (MD) simulations provided insights into structural rearrangements.
Main Results:
- Ethanol CCO and n-hexane CH stretching bands showed complex redshift-blueshift-redshift and blueshift-redshift-blueshift trends, respectively.
- Spectral reshaping and trend reversals occurred near an ethanol volume fraction of 0.4.
- Intermolecular interactions evolved from weak CH⋯O to dominant OH⋯O hydrogen bonds with increasing ethanol content.
Conclusions:
- Composition-driven intermolecular associations directly influence vibrational spectral reorganization.
- A nonmonotonic rearrangement of molecular contacts occurs during mixing.
- DFT and MD simulations successfully explained the observed spectral phenomena and structural changes.
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