TY - JOUR
T1 - Influence of the N atom position on the excited state photodynamics of protonated azaindole
AU - Noble, Jennifer A.
AU - Marceca, Ernesto
AU - Dedonder, Claude
AU - Phasayavan, Witchaya
AU - Féraud, Geraldine
AU - Inceesungvorn, Burapat
AU - Jouvet, Christophe
N1 - Publisher Copyright:
© 2020 the Owner Societies.
PY - 2020/12/14
Y1 - 2020/12/14
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=85097578378&partnerID=8YFLogxK
U2 - 10.1039/d0cp03608k
DO - 10.1039/d0cp03608k
M3 - Article
C2 - 33227118
AN - SCOPUS:85097578378
SN - 1463-9076
VL - 22
SP - 27280
EP - 27289
JO - Physical Chemistry Chemical Physics
JF - Physical Chemistry Chemical Physics
IS - 46
ER -