Femtosecond studies of charge-transfer mediated proton transfer in 2-butylamino-6-methyl-4-nitropyridine N-oxide

Benedek Poór, Natalia Michniewicz, Mihály Kállay, Wybren Jan Buma, Miklós Kubinyi, Anna Szemik-Hojniak, Irena Deperasiñska, Aniela Puszko, Hong Zhang

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Abstract

We have unraveled the effects of an amino substituent in the ortho position on the excited-state dynamics of 4-nitropyridine N-oxide by studying the picosecond fluorescence kinetics and femtosecond transient absorption of a newly synthesized compound, 2-butylamino-6-methyl-4-nitropyridine N-oxide, and by quantum chemical calculations. Similar to the parent compound, the S1 state of the target molecule has significant charge-transfer character and shows a large (∼8000 cm-1) static Stokes shift in acetonitrile. Analysis of the experimental and the theoretical results leads, however, to a new scenario in which this intramolecular charge transfer triggers in polar, aprotic solvents an ultrafast (around 100 fs) intramolecular proton transfer between the amino and the N-O group. The electronically excited N-OH tautomer is subsequently subject to solvent relaxation and decays with a lifetime of ∼ 150 ps to the ground state.

Original languageEnglish
Pages (from-to)7086-7091
Number of pages6
JournalJournal of Physical Chemistry A
Volume110
Issue number22
DOIs
Publication statusPublished - Jun 8 2006

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

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    Poór, B., Michniewicz, N., Kállay, M., Buma, W. J., Kubinyi, M., Szemik-Hojniak, A., Deperasiñska, I., Puszko, A., & Zhang, H. (2006). Femtosecond studies of charge-transfer mediated proton transfer in 2-butylamino-6-methyl-4-nitropyridine N-oxide. Journal of Physical Chemistry A, 110(22), 7086-7091. https://doi.org/10.1021/jp061409z