Influence of the N atom position on the excited state photodynamics of protonated azaindole

Jennifer A. Noble, Ernesto Marceca, Claude Dedonder, Witchaya Phasayavan, Geraldine Féraud, Burapat Inceesungvorn, Christophe Jouvet

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


We present a study of the photofragmentation of three protonated azaindole molecules-7-azaindole, 6-azaindole, and 5-azaindole-consisting of fused pyrrole-pyridine bicyclic aromatic systems, in which the pyridinic (protonated) nitrogen heteroatom is located at the 7, 6, and 5 positions, respectively. Photofragmentation electronic spectra of the isolated aforementioned azaindolinium cations reveal that their photodynamics extends over timescales covering nine orders of magnitude and provide evidence about the resultant fragmentation pathways. Moreover, we show how the position of the heteroatom in the aromatic skeleton influences the excited state energetics, fragmentation pathways, and fragmentation timescales. Computed ab initio adiabatic transition energies are used to assist the assignation of the spectra, while geometry optimisation in the excited electronic states as well as ab initio calculations along the potential surfaces demonstrate the role of ππ*/πσ* coupling and/or large geometry changes in the dynamics of these species. Evidence supporting the formation of Dewar valence isomers as intermediates involved in sub-picosecond relaxation processes is discussed.

Original languageEnglish
Pages (from-to)27280-27289
Number of pages10
JournalPhysical Chemistry Chemical Physics
Issue number46
StatePublished - Dec 14 2020
Externally publishedYes


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