Antioxidants are a class of chemical compounds with particular chemico-physical properties that make them suitable for reducing oxidative stress. In this work we report the rotational spectroscopy analysis of the antioxidant 2,6-di-tert-butylphenol in a jet expansion. The rotational spectrum reveals both fine and hyperfine tunnelling components. The largest spectral doubling consists of two distinct groups of lines separated by ∼190 MHz, and is due to the torsional motion associated with the hydroxyl group. Each component of the doublet is further split into three fine components, with separations below 1 MHz. The spectrum was reproduced with a two-state torsion-rotation semirigid Hamiltonian for each pair of torsional states. Additional observation of all the singly-substituted 13C isotopologues allowed to determine the substitution structure by means of the Kraitchman equations. The comparison with the equilibrium structure obtained by computational calculations at B3LYP-D3BJ/def2-TZVP level validate the accurate determination of the carbon skeleton and tert‑butyl group positions. The investigation of intramolecular dynamics with a monodimensional flexible model demonstrates that the tunnelling phenomenon arises from the hydroxyl group's equivalent positions, with a double-minimum potential separated by a barrier of 1000(100) cm−1 allowing for this large amplitude motion. However, the three-fold fine structurte, while plausibly associated to internal motions within the tert‑butyl group, will require further exploration.

Molecular structure and internal dynamics of the antioxidant 2,6-di-tert-butylphenol / Li W.; Maris A.; Melandri S.; Lesarri A.; Evangelisti L.. - In: JOURNAL OF MOLECULAR STRUCTURE. - ISSN 0022-2860. - STAMPA. - 1296:(2024), pp. 136910.136910-136910.136915. [10.1016/j.molstruc.2023.136910]

Molecular structure and internal dynamics of the antioxidant 2,6-di-tert-butylphenol

Maris A.;Melandri S.;Evangelisti L.
Ultimo
2024

Abstract

Antioxidants are a class of chemical compounds with particular chemico-physical properties that make them suitable for reducing oxidative stress. In this work we report the rotational spectroscopy analysis of the antioxidant 2,6-di-tert-butylphenol in a jet expansion. The rotational spectrum reveals both fine and hyperfine tunnelling components. The largest spectral doubling consists of two distinct groups of lines separated by ∼190 MHz, and is due to the torsional motion associated with the hydroxyl group. Each component of the doublet is further split into three fine components, with separations below 1 MHz. The spectrum was reproduced with a two-state torsion-rotation semirigid Hamiltonian for each pair of torsional states. Additional observation of all the singly-substituted 13C isotopologues allowed to determine the substitution structure by means of the Kraitchman equations. The comparison with the equilibrium structure obtained by computational calculations at B3LYP-D3BJ/def2-TZVP level validate the accurate determination of the carbon skeleton and tert‑butyl group positions. The investigation of intramolecular dynamics with a monodimensional flexible model demonstrates that the tunnelling phenomenon arises from the hydroxyl group's equivalent positions, with a double-minimum potential separated by a barrier of 1000(100) cm−1 allowing for this large amplitude motion. However, the three-fold fine structurte, while plausibly associated to internal motions within the tert‑butyl group, will require further exploration.
2024
Molecular structure and internal dynamics of the antioxidant 2,6-di-tert-butylphenol / Li W.; Maris A.; Melandri S.; Lesarri A.; Evangelisti L.. - In: JOURNAL OF MOLECULAR STRUCTURE. - ISSN 0022-2860. - STAMPA. - 1296:(2024), pp. 136910.136910-136910.136915. [10.1016/j.molstruc.2023.136910]
Li W.; Maris A.; Melandri S.; Lesarri A.; Evangelisti L.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/953757
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