O–H bond fission in 4-substituted phenols: S1 state predissociation viewed in a Hammett-like framework
| Autor: | Tolga N. V. Karsili, Andreas M. Wenge, Stephanie J. Harris, Jeremy N. Harvey, Daniel Murdock, Richard N. Dixon, Michael N. R. Ashfold |
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| Rok vydání: | 2013 |
| Předmět: |
PARASUBSTITUTED PHENOLS
PHOTOELECTRON-SPECTROSCOPY Bond strength Hydrogen bond Chemistry Ab initio SUBSTITUENT CONSTANTS NEAR-UV PHOTOLYSIS General Chemistry Electronic structure Conical intersection Potential energy FLUORESCENCE SPECTROSCOPY P-CYANOPHENOL Computational chemistry Rydberg atom Physical chemistry THRESHOLD IONIZATION SPECTROSCOPY THEORETICAL CALCULATIONS Spectroscopy PHOTOFRAGMENT TRANSLATIONAL SPECTROSCOPY HIGH-RESOLUTION |
| Zdroj: | Karsili, T N V, Wenge, A M, Harris, S J, Murdock, D, Harvey, J N, Dixon, R N & Ashfold, M N R 2013, ' O-H bond fission in 4-substituted phenols: S 1 state predissociation viewed in a Hammett-like framework ', Chemical Science, vol. 4, no. 6, pp. 2434-2446 . https://doi.org/10.1039/c3sc50296a ResearcherID |
| ISSN: | 2041-6539 2041-6520 |
| DOI: | 10.1039/c3sc50296a |
| Popis: | The photofragmentation dynamics of various 4-substituted phenols (4-YPhOH, Y = H, MeO, CH3, F, Cl and CN) following π* ← π excitation to their respective S1 states have been investigated experimentally (by H Rydberg atom photofragment translational spectroscopy) and/or theoretically (by ab initio electronic structure theory and 1- and 2-D tunnelling calculations). Derived energetic and photophysical properties such as the O–H bond strengths, the S1–S0excitation energies and the S1 predissociation probabilities (by tunnelling through the barrier under the conical intersection between the S1(11ππ*) and S2(11πσ*) potential energy surfaces in the RO–H stretch coordinate) are considered within a Hammett-like framework. The Y-dependent O–H bond strengths and S1–S0 term values are found to correlate well with a simple descriptor of the electronic perturbation caused by the aromatic substituent Y (the Hammett constant, σ+p). We also identify clear correlations between σ+p and the probability of a photochemical process (predissociation). Such a finding is unsurprising, given that Y substitution will perturb the entire potential energy landscape, but appears not to have been demonstrated hitherto. The predictive capabilities of this approach are explored by reference to existing energetic data for larger 4-substituted phenols like 4-ethoxyphenol, tyramine, L-tyrosine and tyrosine containing di- and tri-peptides. |
| Databáze: | OpenAIRE |
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