8 research outputs found
Formation of High-Spin States (<i>S</i> = 3/2 and 2) in Linear Oligo- and Polyarylamines
This article describes the study
of a linear trimer and three polyarylamines <b>PB1–3</b> containing a 3,4′-biphenyl ferromagnetic
coupler. The synthesis of the model compound (trimer) and the polymers
has been presented. The formation of radical cations was studied using
electrochemical and optical (UV–vis) methods. The chemical
oxidation of these compounds leads to the creation of high-spin states,
evidenced by pulsed EPR nutation spectroscopy. A quartet spin state
is observed for the trimer model compound, and its <i>J</i> exchange coupling constant has been measured experimentally (<i>J</i>/<i>k</i> = 11.8 K) and compared quantitatively
to DFT calculations. Most importantly, quartet and quintet spin states
have been formed for <b>PB3</b> and <b>PB2</b>, respectively.
These last two doped polymers thus exhibit the highest spin states
observed to date for linear polyarylamine compounds
Ferromagnetic Spin Coupling through the 3,4′-Biphenyl Moiety in Arylamine OligomersExperimental and Computational Study
This
report describes the study of a dimer <b>d</b><sup><b>2+</b></sup> and a linear trimer <b>t</b><sup><b>3+</b></sup> of amminium radical cations coupled by 3,4′-biphenyl
spin coupling units. The synthesis of the parent diamine and triamine
and their optical and electrochemical properties obtained by UV–visible
and cyclic voltammetry are presented. The chemical doping of the parent
diamine <b>d</b> and triamine <b>t</b> was performed quantitatively
to obtain samples containing the corresponding dimer <b>d</b><sup><b>2+</b></sup> and trimer <b>t</b><sup><b>3+</b></sup> in almost pure high-spin states as evidenced by pulsed EPR
nutation spectroscopy. The <i>J</i> coupling constants of
the corresponding <i>S</i> = 1 and <i>S</i> =
3/2 spin states were measured (<i>J</i>/<i>k</i> = 135 K) and compared quantitatively to DFT calculations
Tuning of Ferromagnetic Spin Interactions in Polymeric Aromatic Amines via Modification of Their π‑Conjugated System
Polyarylamine containing <i>meta–para–para</i>-aniline units in the main chain and <i>meta–para</i>-aniline units in the pendant chains was synthesized. The polymer
can be oxidized to radical cations in chemical or electrochemical
ways. The presence of <i>meta</i>-phenylenes in the polymer
chemical structure allows for the ferromagnetic coupling of electronic
spins, which leads to the formation of high spin states. Detailed
pulsed-EPR study indicates that the <i>S</i> = 2 spin state
was reached for the best oxidation level. Quantitative magnetization
measurements reveal that the doped polymer contains mainly <i>S</i> = 2 spin states and a fraction of <i>S</i> =
3/2 spin states. The efficiency of the oxidation was determined to
be 74%. To the best of our knowledge, this polymer is the first example
of a linear doped polyarylamine combining such high spin states with
high doping efficiency
Tuning of Ferromagnetic Spin Interactions in Polymeric Aromatic Amines via Modification of Their π‑Conjugated System
Polyarylamine containing <i>meta–para–para</i>-aniline units in the main chain and <i>meta–para</i>-aniline units in the pendant chains was synthesized. The polymer
can be oxidized to radical cations in chemical or electrochemical
ways. The presence of <i>meta</i>-phenylenes in the polymer
chemical structure allows for the ferromagnetic coupling of electronic
spins, which leads to the formation of high spin states. Detailed
pulsed-EPR study indicates that the <i>S</i> = 2 spin state
was reached for the best oxidation level. Quantitative magnetization
measurements reveal that the doped polymer contains mainly <i>S</i> = 2 spin states and a fraction of <i>S</i> =
3/2 spin states. The efficiency of the oxidation was determined to
be 74%. To the best of our knowledge, this polymer is the first example
of a linear doped polyarylamine combining such high spin states with
high doping efficiency
Tuning of Ferromagnetic Spin Interactions in Polymeric Aromatic Amines via Modification of Their π‑Conjugated System
Polyarylamine containing <i>meta–para–para</i>-aniline units in the main chain and <i>meta–para</i>-aniline units in the pendant chains was synthesized. The polymer
can be oxidized to radical cations in chemical or electrochemical
ways. The presence of <i>meta</i>-phenylenes in the polymer
chemical structure allows for the ferromagnetic coupling of electronic
spins, which leads to the formation of high spin states. Detailed
pulsed-EPR study indicates that the <i>S</i> = 2 spin state
was reached for the best oxidation level. Quantitative magnetization
measurements reveal that the doped polymer contains mainly <i>S</i> = 2 spin states and a fraction of <i>S</i> =
3/2 spin states. The efficiency of the oxidation was determined to
be 74%. To the best of our knowledge, this polymer is the first example
of a linear doped polyarylamine combining such high spin states with
high doping efficiency
Tuning of Ferromagnetic Spin Interactions in Polymeric Aromatic Amines via Modification of Their π‑Conjugated System
Polyarylamine containing <i>meta–para–para</i>-aniline units in the main chain and <i>meta–para</i>-aniline units in the pendant chains was synthesized. The polymer
can be oxidized to radical cations in chemical or electrochemical
ways. The presence of <i>meta</i>-phenylenes in the polymer
chemical structure allows for the ferromagnetic coupling of electronic
spins, which leads to the formation of high spin states. Detailed
pulsed-EPR study indicates that the <i>S</i> = 2 spin state
was reached for the best oxidation level. Quantitative magnetization
measurements reveal that the doped polymer contains mainly <i>S</i> = 2 spin states and a fraction of <i>S</i> =
3/2 spin states. The efficiency of the oxidation was determined to
be 74%. To the best of our knowledge, this polymer is the first example
of a linear doped polyarylamine combining such high spin states with
high doping efficiency
Tuning of Ferromagnetic Spin Interactions in Polymeric Aromatic Amines via Modification of Their π‑Conjugated System
Polyarylamine containing <i>meta–para–para</i>-aniline units in the main chain and <i>meta–para</i>-aniline units in the pendant chains was synthesized. The polymer
can be oxidized to radical cations in chemical or electrochemical
ways. The presence of <i>meta</i>-phenylenes in the polymer
chemical structure allows for the ferromagnetic coupling of electronic
spins, which leads to the formation of high spin states. Detailed
pulsed-EPR study indicates that the <i>S</i> = 2 spin state
was reached for the best oxidation level. Quantitative magnetization
measurements reveal that the doped polymer contains mainly <i>S</i> = 2 spin states and a fraction of <i>S</i> =
3/2 spin states. The efficiency of the oxidation was determined to
be 74%. To the best of our knowledge, this polymer is the first example
of a linear doped polyarylamine combining such high spin states with
high doping efficiency