Ultrafast branching of reaction pathways in 2-(2′-hydroxyphenyl) benzothiazole in polar acetonitrile solution

Omar Abdelsaboor, Sandra Luber, Victor S. Batista, Erik T.J. Nibbering*

*Corresponding author for this work

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61 Scopus citations


In a combined study on the photophysics of 2-(2′-hydroxyphenyl)- benzothiazole (HBT) in polar acetonitrile utilizing ultrafast infrared spectroscopy and quantum chemical calculations, we show that a branching of reaction pathways occurs on femtosecond time scales. Apart from the excited-state intramolecular hydrogen transfer (ESIHT) converting electronically excited enol tautomer into the keto tautomer, known to be the dominating mechanism of HBT in nonpolar solvents such as cyclohexane and tetrachloroethene, in acetonitrile solution twisting also occurs around the central C-C bond connecting the hydroxyphenyl and benzothiazole units in both electronically excited enol and keto tautomers. The solvent-induced intramolecular twisting enables efficient internal conversion pathways to both enol and keto tautomers in the electronic ground state. Whereas relaxation to the most stable enol tautomer with twisting angle Θ = 0° implies full ground state recovery, a small fraction of HBT molecules persists as the keto twisting conformer with the twisting angle Θ = 180° for delay times extending beyond 120 ps.

Original languageEnglish (US)
Pages (from-to)7550-7558
Number of pages9
JournalJournal of Physical Chemistry A
Issue number26
StatePublished - Jul 7 2011

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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