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Solvent induced conformer specific photochemistry of guaiacol
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Greenough, Simon E., Horbury, Michael D., Thompson, James O. F., Roberts, Gareth M., Karsili, Tolga N. V., Marchetti, Barbara, Townsend, Dave and Stavros, Vasilios G. (2014) Solvent induced conformer specific photochemistry of guaiacol. Physical Chemistry Chemical Physics, Volume 16 (Number 30). pp. 16187-16195. Article number 16187. doi:10.1039/c4cp02424a ISSN 1463-9076.
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Official URL: http://dx.doi.org/10.1039/c4cp02424a
Abstract
Using a combination of ultrafast solution- and gas-phase spectroscopies, together with high-level theory calculations, we demonstrate that we are able to track conformer-specific photodissociation dynamics in solution through solvent choice. We reveal this phenomenon in guaiacol (2-methoxyphenol), a key subunit of the natural biopolymer lignin. In cyclohexane, the first electronically excited 1ππ* (S1) state in guaiacol relaxes with a time-constant of τ = 4.5 ± 0.2 ns, mediated through intersystem crossing to lower lying triplet (Tn) states and internal conversion and fluorescence back to the ground state (S0). In contrast, in methanol, a further relaxation channel is also present; the S1 state relaxes with a time-constant of τ = 2.9 ± 0.1 ns, which is now additionally mediated through coupling onto a dissociative 1πσ* (S2) state and subsequent O–H bond fission, evidenced through the appearance of a spectral signature for the guaiacoxyl radical after [similar]250 ps. With the aid of complementary calculations, we attribute this to the now absent intramolecular H-bond between OH and OMe moieties, which now favours intermolecular H-bonding to methanol, lowering the barrier to O–H dissociation and facilitating H-atom loss via tunnelling.
Item Type: | Journal Article | ||||||||
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Divisions: | Faculty of Science, Engineering and Medicine > Science > Chemistry | ||||||||
Journal or Publication Title: | Physical Chemistry Chemical Physics | ||||||||
Publisher: | Royal Society of Chemistry | ||||||||
ISSN: | 1463-9076 | ||||||||
Official Date: | 18 June 2014 | ||||||||
Dates: |
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Volume: | Volume 16 | ||||||||
Number: | Number 30 | ||||||||
Page Range: | pp. 16187-16195 | ||||||||
Article Number: | Article number 16187 | ||||||||
DOI: | 10.1039/c4cp02424a | ||||||||
Status: | Peer Reviewed | ||||||||
Publication Status: | Published | ||||||||
Access rights to Published version: | Restricted or Subscription Access |
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