Solvent-dependent photoinduced tautomerization of 2-(2′-hydroxyphenyl)benzoxazole

Osama K. Abou-Zied, Ralph Jimenez, Elizabeth H Z Thompson, David P. Millar, Floyd E. Romesberg

Research output: Contribution to journalArticle

144 Citations (Scopus)

Abstract

The solvent-dependent ground-state conformational equilibrium and excited-state dynamics of 2-(2′-hydroxyphenyl)benzoxazole have been characterized in several solvents on the femtosecond to nanosecond time scales. The only observable ground-state tautomer is the enol, which exists in equilibrium between the syn- and anti-rotational isomers. In the anti-enol isomer, the phenyl hydroxyl group appears to not interact strongly with solvent but rather forms a strong intramolecular hydrogen bond with the benzoxazole oxygen atom. In the syn-enol isomer, the phenyl hydroxyl proton may interact with solvent or form an internal hydrogen bond with the benzoxazole nitrogen atom. Upon excitation, the proton is transferred from the oxygen atom to the nitrogen atom of the internally hydrogen bonded syn-enol isomer in 170 fs, regardless of the solvent. The lifetime of the resulting excited keto tautomer is solvent dependent and on the order of picoseconds. In addition to these dynamics, several additional dynamic processes are detected which may correspond to relaxation of a distorted excited keto tautomer.

Original languageEnglish
Pages (from-to)3665-3672
Number of pages8
JournalJournal of Physical Chemistry A
Volume106
Issue number15
DOIs
Publication statusPublished - Apr 18 2002

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Benzoxazoles
Isomers
tautomers
isomers
Atoms
Hydroxyl Radical
nitrogen atoms
Ground state
Protons
oxygen atoms
Hydrogen bonds
Nitrogen
hydrogen bonds
Oxygen
ground state
protons
Excited states
excitation
Hydrogen
life (durability)

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Solvent-dependent photoinduced tautomerization of 2-(2′-hydroxyphenyl)benzoxazole. / Abou-Zied, Osama K.; Jimenez, Ralph; Thompson, Elizabeth H Z; Millar, David P.; Romesberg, Floyd E.

In: Journal of Physical Chemistry A, Vol. 106, No. 15, 18.04.2002, p. 3665-3672.

Research output: Contribution to journalArticle

Abou-Zied, Osama K. ; Jimenez, Ralph ; Thompson, Elizabeth H Z ; Millar, David P. ; Romesberg, Floyd E. / Solvent-dependent photoinduced tautomerization of 2-(2′-hydroxyphenyl)benzoxazole. In: Journal of Physical Chemistry A. 2002 ; Vol. 106, No. 15. pp. 3665-3672.
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N2 - The solvent-dependent ground-state conformational equilibrium and excited-state dynamics of 2-(2′-hydroxyphenyl)benzoxazole have been characterized in several solvents on the femtosecond to nanosecond time scales. The only observable ground-state tautomer is the enol, which exists in equilibrium between the syn- and anti-rotational isomers. In the anti-enol isomer, the phenyl hydroxyl group appears to not interact strongly with solvent but rather forms a strong intramolecular hydrogen bond with the benzoxazole oxygen atom. In the syn-enol isomer, the phenyl hydroxyl proton may interact with solvent or form an internal hydrogen bond with the benzoxazole nitrogen atom. Upon excitation, the proton is transferred from the oxygen atom to the nitrogen atom of the internally hydrogen bonded syn-enol isomer in 170 fs, regardless of the solvent. The lifetime of the resulting excited keto tautomer is solvent dependent and on the order of picoseconds. In addition to these dynamics, several additional dynamic processes are detected which may correspond to relaxation of a distorted excited keto tautomer.

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