10.1021/jo048489s.s001
Shunji Ito
Shunji
Ito
Takahiro Kubo
Takahiro
Kubo
Noboru Morita
Noboru
Morita
Tadaaki Ikoma
Tadaaki
Ikoma
Shozo Tero-Kubota
Shozo
Tero-Kubota
Jun Kawakami
Jun
Kawakami
Akio Tajiri
Akio
Tajiri
Azulene-Substituted Aromatic Amines. Synthesis and Amphoteric
Redox Behavior of <i>N</i>,<i>N</i>-Di(6-azulenyl)-<i>p</i>-toluidine and
<i>N</i>,<i>N</i>,<i>N</i>‘,<i>N</i>‘-Tetra(6-azulenyl)-<i>p</i>-phenylenediamine and Their
Derivatives
American Chemical Society
2005
dianion diradicals
compound
amine 1 b
azulenyl
amphoteric redox materials
UV
phenylenediamine
absorption maxima
amines
diamine 2 b
exhibit electrochemical oxidation
species
nm
Di
Amphoteric Redox Behavior
toluidine
ESR
anion radicals
electrochemical reduction
2005-03-18 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/Azulene_Substituted_Aromatic_Amines_Synthesis_and_Amphoteric_Redox_Behavior_of_i_N_i_i_N_i_Di_6_azulenyl_i_p_i_toluidine_and_i_N_i_i_N_i_i_N_i_i_N_i_Tetra_6_azulenyl_i_p_i_phenylenediamine_and_Their_Derivatives/3295825
<i>N</i>,<i>N</i>-Di(6-azulenyl)-<i>p</i>-toluidine (<b>1a</b>) and <i>N</i>,<i>N</i>,<i>N</i>‘,<i>N</i>‘-tetra(6-azulenyl)-<i>p</i>-phenylenediamine (<b>2a</b>) and
their derivatives with 1,3-bis(ethoxycarbonyl) substituents on each 6-azulenyl group (<b>1b</b> and <b>2b</b>)
were prepared by Pd-catalyzed amine azulenylation and characterized as a study into new aromatic
amines for multistage amphoteric redox materials. The redox behavior of each compound was
characterized by cyclic voltammetry. These compounds undergo facile reduction to stable anion
radicals and dianion diradicals owing to the resonance stabilization between the 6-azulenyl groups
and exhibit electrochemical oxidation depending on the amine subunits. The ESR measurement of
anion radicals and a dianion diradical generated by the electrochemical reduction of amine <b>1b</b> and
diamine <b>2b</b> revealed that the unpaired electron of these radicals delocalizes over the entire azulene
ring including the central nitrogen atoms. UV−vis spectral analysis of amines <b>1a</b>,<b>b</b> and diamines
<b>2a</b>,<b>b</b>, taken during the electrochemical reduction, exhibited a gradual decrease of the absorption
bands of the neutral species along with an increase of the new absorption maxima at 625, 605,
640, and 610 nm, respectively, with the development of well-defined isosbestic points at 502, 562,
478, and 545 nm, respectively. As indicated by a combined ESR and UV−vis spectral study, the
species giving rise to the new absorption maxima are concluded to be the generation of anion radicals
and dianion diradicals of aromatic amines and diamines with high thermodynamic stability.