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Time-Resolved Photoelectron Spectroscopy Studies of Isoxazole and Oxazole
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- Geng, Ting (author)
- Stockholms universitet,Fysikum
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Ehrmaier, Johannes (author)
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- Schalk, Oliver (author)
- Stockholms universitet,Fysikum,University of Copenhagen, Denmark
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Richings, Gareth W. (author)
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- Hansson, Tony (author)
- Stockholms universitet,Fysikum
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Worth, Graham (author)
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- Thomas, Richard D. (author)
- Stockholms universitet,Fysikum
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(creator_code:org_t)
- 2020-04-03
- 2020
- English.
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In: Journal of Physical Chemistry A. - : American Chemical Society (ACS). - 1089-5639 .- 1520-5215. ; 124:20, s. 3984-3992
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https://doi.org/10.1...
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https://pubs.acs.org...
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https://urn.kb.se/re...
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Abstract
Subject headings
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- The excited state relaxation pathways of isoxazole and oxazole upon excitation with UV-light were investigated by nonadiabatic ab initio dynamics simulations and time-resolved photoelectron spectroscopy. Excitation of the bright ππ*-state of isoxazole predominantly leads to ring-opening dynamics. Both the initially excited ππ*-state and the dissociative πσ*-state offer a combined barrier-free reaction pathway, such that ring-opening, defined as a distance of more than 2 Å between two neighboring atoms, occurs within 45 fs. For oxazole, in contrast, the excited state dynamics is about twice as slow (85 fs) and the quantum yield for ring-opening is lower. This is caused by a small barrier between the ππ*-state and the πσ*-state along the reaction path, which suppresses direct ring-opening. Theoretical findings are consistent with the measured time-resolved photoelectron spectra, confirming the timescales and the quantum yields for the ring-opening channel. The results indicate that a combination of time-resolved photoelectron spectroscopy and excited state dynamics simulations can explain the dominant reaction pathways for this class of molecules. As a general rule, we suggest that the antibonding σ*-orbital located between the oxygen atom and a neighboring atom of a five-membered heterocyclic system provides a driving force for ring-opening reactions, which is modified by the presence and position of additional nitrogen atoms.
Subject headings
- NATURVETENSKAP -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)
- NATURVETENSKAP -- Kemi -- Fysikalisk kemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Physical Chemistry (hsv//eng)
Publication and Content Type
- ref (subject category)
- art (subject category)
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