Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters
The conformational preferences of the ester group have the potential to facilitate the large amplitude folding of long alkyl chains in the gas phase. They are monitored by Raman spectroscopy in supersonic jet expansions for the model system methyl butanoate, after establishing a quantitative relatio...
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MDPI AG
2021-07-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/26/15/4523 |
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| author | Maxim Gawrilow Martin A. Suhm |
| author_facet | Maxim Gawrilow Martin A. Suhm |
| author_sort | Maxim Gawrilow |
| collection | DOAJ |
| description | The conformational preferences of the ester group have the potential to facilitate the large amplitude folding of long alkyl chains in the gas phase. They are monitored by Raman spectroscopy in supersonic jet expansions for the model system methyl butanoate, after establishing a quantitative relationship with quantum–chemical predictions for methyl methanoate. This requires a careful analysis of experimental details, and a simulation of the rovibrational contours for near-symmetric top molecules. The technique is shown to be complementary to microwave spectroscopy in quantifying coexisting conformations. It confirms that a <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">C</mi><mo>−</mo><mi mathvariant="normal">O</mi><mo>−</mo><mi mathvariant="normal">C</mi><mo>(</mo><mo>=</mo><mi mathvariant="normal">O</mi><mo>)</mo><mo>–</mo><mi mathvariant="normal">C</mi><mo>–</mo><mi mathvariant="normal">C</mi></mrow></semantics></math></inline-formula> chain segment can be collapsed into a single all-trans conformation by collisional cooling, whereas alkyl chain isomerism beyond this five-membered chain largely survives the jet expansion. This sets the stage for the investigation of linear alkyl alkanoates in terms of dispersion-induced stretched-chain to hairpin transitions by Raman spectroscopy. |
| first_indexed | 2024-03-10T09:10:48Z |
| format | Article |
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| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-03-10T09:10:48Z |
| publishDate | 2021-07-01 |
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| spelling | doaj.art-18c1edd217d34f4b8aac1f5e0edcdba02023-11-22T05:59:22ZengMDPI AGMolecules1420-30492021-07-012615452310.3390/molecules26154523Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl EstersMaxim Gawrilow0Martin A. Suhm1Institut für Physikalische Chemie, Georg-August-Universität Göttingen, Tammannstr. 6, 37077 Göttingen, GermanyInstitut für Physikalische Chemie, Georg-August-Universität Göttingen, Tammannstr. 6, 37077 Göttingen, GermanyThe conformational preferences of the ester group have the potential to facilitate the large amplitude folding of long alkyl chains in the gas phase. They are monitored by Raman spectroscopy in supersonic jet expansions for the model system methyl butanoate, after establishing a quantitative relationship with quantum–chemical predictions for methyl methanoate. This requires a careful analysis of experimental details, and a simulation of the rovibrational contours for near-symmetric top molecules. The technique is shown to be complementary to microwave spectroscopy in quantifying coexisting conformations. It confirms that a <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="normal">C</mi><mo>−</mo><mi mathvariant="normal">O</mi><mo>−</mo><mi mathvariant="normal">C</mi><mo>(</mo><mo>=</mo><mi mathvariant="normal">O</mi><mo>)</mo><mo>–</mo><mi mathvariant="normal">C</mi><mo>–</mo><mi mathvariant="normal">C</mi></mrow></semantics></math></inline-formula> chain segment can be collapsed into a single all-trans conformation by collisional cooling, whereas alkyl chain isomerism beyond this five-membered chain largely survives the jet expansion. This sets the stage for the investigation of linear alkyl alkanoates in terms of dispersion-induced stretched-chain to hairpin transitions by Raman spectroscopy.https://www.mdpi.com/1420-3049/26/15/4523Raman intensityconformational isomerismchain foldingjet coolingrotational band contouresters |
| spellingShingle | Maxim Gawrilow Martin A. Suhm Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters Molecules Raman intensity conformational isomerism chain folding jet cooling rotational band contour esters |
| title | Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters |
| title_full | Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters |
| title_fullStr | Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters |
| title_full_unstemmed | Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters |
| title_short | Quantifying Conformational Isomerism in Chain Molecules by Linear Raman Spectroscopy: The Case of Methyl Esters |
| title_sort | quantifying conformational isomerism in chain molecules by linear raman spectroscopy the case of methyl esters |
| topic | Raman intensity conformational isomerism chain folding jet cooling rotational band contour esters |
| url | https://www.mdpi.com/1420-3049/26/15/4523 |
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