A Broadband Rotational Spectroscopic And Theoretical Study Of Cis And Trans (-)-carveol

Hazrah, Arsh Singh

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https://hdl.handle.net/2142/111270 Copy

Description

Title

A Broadband Rotational Spectroscopic And Theoretical Study Of Cis And Trans (-)-carveol

Author(s)

Hazrah, Arsh Singh

Contributor(s)

• Jäger, Wolfgang
• Speelman, Raiden
• Al-Jabiri, Mohamad

Issue Date

2021-06-25

Keyword(s)

Chirality and stereochemistry

Abstract

Carveol, a primary constituent in spearmint and peppermint oil, is a monocyclic monoterpenoid alcohol that is produced in nature by the photooxidation of limonene.$^{1}$ Structurally, carveol contains two chiral centers with three substituents (methyl group, hydroxyl group, and propylene group) attached to it’s cyclohexane ring. The combination of the three flexible substituents, ring puckering, and two chiral centers introduce a complex conformational topography that is non-trivial to elucidate. However, a thorough study of the topology of chiral carveol may provide valuable insights into complex conformational dynamics, as well as chirality recognitions studies. We believe chirped-pulse Fourier transform microwave spectroscopy (CP-FTMW) is an excellent tool for this investigation as it is able to unambiguously distinguish structural conformers within a complex mixture.$^{2}$ The broadband rotational spectrum of cis and trans (-)-carveol was recorded using a chirped pulse Fourier Transform microwave spectrometer in the 2-6 GHz region.$^{3}$ To aid in experimental assignment, a theoretical conformational search was carried out using a combination of a two dimensional potential energy scan, which scans over the propylene group and hydroxyl group, and the Conformer–Rotamer Ensemble Sampling Tool (CREST).$^{4}$ The theoretical results yielded a total of 23 conformers for the trans and 19 for the cis. Utilizing these results, a total of five experimental conformers were then assigned: two for the trans conformer and three for the cis conformer. For trans, it was determined both experimental conformers occupy the equatorial position. For the cis conformer, two equatorial and one axial conformer was experimentally assigned. The conformational cooling pathways and intermolecular interactions within each conformer were also analyzed to further understand the conformational landscape of cis and trans (-)-carveol. 1. J. Laothawornkitkul, J. E. Taylor, N. D. Paul and C. N. Hewitt, New Phytol., 2009, 183, 27–51.; 2. G. Barratt Park, and Robert W. Field, J. Chem. Phys., 2016, 144, 20090.; 3. N. A. Seifert, J. Thomas, W. Jäger and Y. Xu, Phys. Chem. Chem. Phys., 2018, 20, 27630–27637.; 4. P. Pracht, F. Bohle, S. Grimme, Phys. Chem. Chem. Phys. 2020., 22(14), 7169-7192

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Permalink

http://hdl.handle.net/2142/111270

DOI

10.15278/isms.2021.FM05

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