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Electronic Spectroscopy of Protonated 1‐Aminopyrene in a Cold Ion Trap
Author(s) -
Noble Jennifer Anna,
DedonderLardeux Claude,
Mascetti Joëlle,
Jouvet Christophe
Publication year - 2017
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201700327
Subject(s) - protonation , chemistry , tautomer , excited state , spectroscopy , photochemistry , fragmentation (computing) , ion , computational chemistry , stereochemistry , organic chemistry , atomic physics , physics , quantum mechanics , computer science , operating system
Abstract In aromatic systems that contain an amino group, there is competition between protonation on a carbon atom of the skeleton and protonation on the amino group. Herein, we studied the photofragmentation of protonated 1‐aminopyrene in a cold ion trap and mainly observed the protonated amino tautomer, which led to fragmentation pathways through the loss of H or NH 3 groups. Several excited states were assigned, among which the fourth excited state showed broadened bands, thus indicating a fast decay that was attributed to the presence of a πσ* charge‐transfer state by comparison of the experimental results with ab initio calculations. We deduced the πσ* transition energies in protonated aromatic amino compounds of increasing size directly from the ionization potentials of the neutral aromatic unsubstituted molecules. Tautomers that were protonated on a carbon atom of the pyrene skeleton were also weakly observed, and we showed that two tautomers that were protonated on a carbon atom of the aromatic ring could be distinguished by using electronic spectroscopy.