Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass Spectroscopy
Pivaldehyde, which is an unwanted by-product released with engine exhaust, has received considerable research attention because of its hydrocarbon oxidations at atmospheric temperature. To gain insight into the conformer-specific reaction dynamics, we investigated the conformational structures of th...
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MDPI AG
2022-11-01
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| Series: | International Journal of Molecular Sciences |
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| Online Access: | https://www.mdpi.com/1422-0067/23/23/14777 |
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| author | Sung Man Park Yu Ran Lee Chan Ho Kwon |
| author_facet | Sung Man Park Yu Ran Lee Chan Ho Kwon |
| author_sort | Sung Man Park |
| collection | DOAJ |
| description | Pivaldehyde, which is an unwanted by-product released with engine exhaust, has received considerable research attention because of its hydrocarbon oxidations at atmospheric temperature. To gain insight into the conformer-specific reaction dynamics, we investigated the conformational structures of the pivaldehyde molecule in neutral (S<sub>0</sub>) and cationic (D<sub>0</sub>) states using the recently invented IR-resonant VUV-MATI mass spectroscopy. Additionally, we constructed the two-dimensional potential energy surfaces (2D PESs) associated with the conformational transformations in the S<sub>0</sub> and D<sub>0</sub> states to deduce the conformations corresponding to the measured vibrational spectra. The 2D PESs indicated the presence of only the <i>eclipsed</i> conformation in the global minima of both states, unlike those in propanal and isobutanal. However, comparing the IR-dip VUV-MATI spectra from two intense peaks in the VUV-MATI spectrum with the anharmonic IR simulations revealed the correspondence between the <i>gauche</i> conformer on the S<sub>0</sub> state and the measured IR spectra. Furthermore, Franck–Condon analysis confirmed that most peaks in the VUV-MATI spectrum are attributed to the adiabatic ionic transitions between the neutral <i>gauche</i> and cationic <i>eclipsed</i> conformers in pivaldehyde. Consequently, electron removal from the highest occupied molecular orbital, consisting of the nonbonding orbital of the oxygen atom in pivaldehyde, promoted the formyl-relevant modes in the induced cationic <i>eclipsed</i> conformer. |
| first_indexed | 2024-03-09T17:46:40Z |
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| issn | 1661-6596 1422-0067 |
| language | English |
| last_indexed | 2024-03-09T17:46:40Z |
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| series | International Journal of Molecular Sciences |
| spelling | doaj.art-9c5e095cebcf4d4bb8ef69e9c3bea6dc2023-11-24T11:07:44ZengMDPI AGInternational Journal of Molecular Sciences1661-65961422-00672022-11-0123231477710.3390/ijms232314777Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass SpectroscopySung Man Park0Yu Ran Lee1Chan Ho Kwon2Department of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Republic of KoreaForensic Chemistry Division, National Forensic Service, Wonju 26460, Republic of KoreaDepartment of Chemistry and Institute for Molecular Science and Fusion Technology, Kangwon National University, Chuncheon 24341, Republic of KoreaPivaldehyde, which is an unwanted by-product released with engine exhaust, has received considerable research attention because of its hydrocarbon oxidations at atmospheric temperature. To gain insight into the conformer-specific reaction dynamics, we investigated the conformational structures of the pivaldehyde molecule in neutral (S<sub>0</sub>) and cationic (D<sub>0</sub>) states using the recently invented IR-resonant VUV-MATI mass spectroscopy. Additionally, we constructed the two-dimensional potential energy surfaces (2D PESs) associated with the conformational transformations in the S<sub>0</sub> and D<sub>0</sub> states to deduce the conformations corresponding to the measured vibrational spectra. The 2D PESs indicated the presence of only the <i>eclipsed</i> conformation in the global minima of both states, unlike those in propanal and isobutanal. However, comparing the IR-dip VUV-MATI spectra from two intense peaks in the VUV-MATI spectrum with the anharmonic IR simulations revealed the correspondence between the <i>gauche</i> conformer on the S<sub>0</sub> state and the measured IR spectra. Furthermore, Franck–Condon analysis confirmed that most peaks in the VUV-MATI spectrum are attributed to the adiabatic ionic transitions between the neutral <i>gauche</i> and cationic <i>eclipsed</i> conformers in pivaldehyde. Consequently, electron removal from the highest occupied molecular orbital, consisting of the nonbonding orbital of the oxygen atom in pivaldehyde, promoted the formyl-relevant modes in the induced cationic <i>eclipsed</i> conformer.https://www.mdpi.com/1422-0067/23/23/14777conformer-specific vibrational spectroscopyphotoionizationFranck–Condon analysistrimethylacetaldehydeVUV-MATI |
| spellingShingle | Sung Man Park Yu Ran Lee Chan Ho Kwon Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass Spectroscopy International Journal of Molecular Sciences conformer-specific vibrational spectroscopy photoionization Franck–Condon analysis trimethylacetaldehyde VUV-MATI |
| title | Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass Spectroscopy |
| title_full | Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass Spectroscopy |
| title_fullStr | Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass Spectroscopy |
| title_full_unstemmed | Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass Spectroscopy |
| title_short | Conformational Structures of Neutral and Cationic Pivaldehyde Revealed by IR-Resonant VUV-MATI Mass Spectroscopy |
| title_sort | conformational structures of neutral and cationic pivaldehyde revealed by ir resonant vuv mati mass spectroscopy |
| topic | conformer-specific vibrational spectroscopy photoionization Franck–Condon analysis trimethylacetaldehyde VUV-MATI |
| url | https://www.mdpi.com/1422-0067/23/23/14777 |
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