N,N-bis(4-{5-[N,N-bis(4-methoxyphenyl)-N-yloammonio]-2-methylstyryl}phenyl) ammoniumyl triradical: A trimer model of high-spin poly[(4-methoxyphenyl-N- yloammonio)-1,2(or 4)-phenylenevinylene-1,2(or 4)-phenylene]

Article abstract of DOI:10.1246/bcsj.79.953

Hyperbranched poly[(4-methoxyphenyl-N-yloammonio)-1,2(or 4)-phenylenevinylene-1,2(or 4)-phenylene], obtained by the polycondensation of N-(4-methoxyphenyl)-N-(4-vinylphenyl)-3-bromo-4-vinylaniline and the subsequent oxidation, three-directionally satisfie

Full text of DOI:10.1246/bcsj.79.953

ꢀ 2006 The Chemical Society of Japan
Bull. Chem. Soc. Jpn. Vol. 79, No. 6, 953–958 (2006)
953
N,N-Bis(4-{5-[N,N-bis(4-methoxyphenyl)-N-yloammonio]-2-
methylstyryl}phenyl)ammoniumyl Triradical: A Trimer
Model of High-Spin Poly[(4-methoxyphenyl-N-yloammonio)-
1,2(or 4)-phenylenevinylene-1,2(or 4)-phenylene]
ꢀ
Eiji Fukuzaki, Shigemoto Abe, and Hiroyuki Nishide
Department of Applied Chemistry, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555
Received November 28, 2005; E-mail: nishide@waseda.jp
Hyperbranched poly[(4-methoxyphenyl-N-yloammonio)-1,2(or 4)-phenylenevinylene-1,2(or 4)-phenylene], ob-
tained by the polycondensation of N-(4-methoxyphenyl)-N-(4-vinylphenyl)-3-bromo-4-vinylaniline and the subsequent
´
oxidation, three-directionally satisfied the non-Kekule-type ꢀ-conjugation and ferromagnetic connectivity of the un-
paired electrons of triarylammoniumyl cationic radicals, and behaved as a high-spin organic polymer even at room tem-
perature. The trimer model compound, N-(4-{5-[N,N-bis(4-methoxyphenyl)amino]-2-methylstyryl}-3-methylphenyl)-N-
(4-{5-[N,N-bis(4-methoxyphenyl)amino]-2-methylstyryl}phenyl)-4-methoxyaniline, was synthesized from N-(4-me-
thoxyphenyl)-N-(4-vinylphenyl)-3-methyl-4-vinylaniline. The corresponding ammoniumyl triradical displayed an aver-
age S (spin quantum number) value of 3/2, which supported the strong spin-coupling between the unpaired electrons of
the ammoniumyl radicals through the ꢀ-conjugated and branched phenylenevinylene structure. Head-to-tail linkage and
the branched structure of the polymer were also studied by a model reaction of N-(4-methoxyphenyl)-N-(4-vinylphenyl)-
3-methyl-4-vinylaniline and bromobenzene.
There is still a strong research interest in the synthesis of
purely organic-derived high-spin polymers because they are
possible candidates for magnetically active organic materi-
als.1–7 The high-spin polymers have been synthesized to satisfy
radical. We have recently succeeded in synthesizing poly[(4-
methoxyphenyl-N-yloammonio)-1,2(or 4)-phenylenevinylene-
1,2(or 4)-phenylene] (1) (Fig. 1), which is the first example
of a room temperature high-spin, purely organic polymer.27
The hyperbranched polyammoniumyl radical 1 was obtained
via the one-pot polycondensation of an asymmetric trifunc-
tional ABB0-type monomer, N-(4-methoxyphenyl)-N-(4-vinyl-
phenyl)-3-bromo-4-vinylaniline, and the subsequent oxidation.
Usually, hyperbranched polymers are easily prepared via a
one-pot polymerization; however, the produced polymers in-
volve irregular structures including unreacted branch points,
´
non-Kekule-type and non-disjoint connectivity among the un-
paired electrons of the radical moieties through the ꢀ-conju-
gated skeleton of the polymers.8–17 Chemically stable radical
species would facilitate studies of such high-spin polymers.
We selected triarylammoniumyl radicals as a favorable source
of the unpaired electron, which satisfies both the chemical sta-
bility and efficient delocalization of the spin-density for the
high-spin alignment.18–22
On the other hand, the high-spin polymers have been recent-
ly extended to the branched and/or dendritic ꢀ-conjugation an-
alogues to enhance the strong spin-alignment through the ꢀ-
conjugated skeleton.23–26 For example, Rajca et al. synthesized
two-dimensionally dendritic-macrocyclic poly(1,3-phenylene-
phenylmethine)s and reported a huge magnetic moment corre-
sponding to an S (spin quantum number) > 5000;11 that is, the
unpaired electrons of the radicals multi-directionally and quasi
two- or three-dimensionally couple with a high number of the
neighboring radicals’ unpaired electrons through the branched
or dendritic ꢀ-conjugation pathway in order to stabilize the
high-spin ground state and increase the spin-alignment number.
A combination of the multi-directionally extended ꢀ-conjuga-
tion with a chemically stable radical species such as the triaryl-
ammoniumyl radical was expected27 to provide the possibility
of a high-spin polymer as a magnetically active material and
possibly raise the temperature range of the high-spin ordering.
Hyperbranched polymerization28,29 is one of the methods to
prepare a highly branched ꢀ-conjugation skeleton for the poly-
Fig. 1. Structure of the hyperbranched poly[(4-methoxy-
phenyl-N-yloammonio)-1,2(or 4)-phenylenevinylene-1,2-
(or 4)-phenylene] (1).
Published on the web June 6, 2006; doi:10.1246/bcsj.79.953

954 Bull. Chem. Soc. Jpn. Vol. 79, No. 6 (2006)
Quartet Ammoniumyl Triradical
when compared to the analogous dendrimers.27,28 The magnet-
ic property or the high-spin alignment of the hyperbranched
polyradical 1 is presumed to depend upon its branched ꢀ-con-
jugation structure. Characterization of the hyperbranched
structure of the high-spin polymer 1 is crucial in order to elu-
cidate the outstanding magnetic property of 1.
This paper describes the synthesis of the key model com-
pound of the high-spin polymer 1 or the trimer of 1, N-(4-
{5-[N,N-bis(4-methoxyphenyl)amino]-2-methylstyryl}-3-meth-
ylphenyl)-N-(4-{5-[N,N-bis(4-methoxyphenyl)amino]-2-meth-
ylstyryl}phenyl)-4-methoxyaniline (2), from N-(4-methoxy-
phenyl)-N-(4-vinylphenyl)-3-methyl-4-vinylaniline (3) and
N,N-bis(4-methoxyphenyl)-3-bromo-4-methylaniline (4), and
its quartet high-spin property or the effective spin-coupling
through the designed ꢀ-conjugation. The branched structure
and degree of branching of the hyperbranched polymer 1 are
also discussed in this paper based on the model reaction of
N-(4-methoxyphenyl)-N-(4-vinylphenyl)-3-methyl-4-vinylani-
line (3) and bromobenzene using the same Pd-catalyzed con-
densation conditions for the formation of 1.
using differential pulse voltammetry (ip1=ip2 ¼ 2; peak current
(ip1; ip2) at 0.70 and 0.85 V are 18 and 9.4 mA). The first and
second oxidation waves involved two- and one-electron proc-
esses, respectively. The rotating disc voltammetry for the oxi-
dation of 2 also revealed a two-step oxidation current (il1=
ðil2 ꢁ il1Þ ¼ 2; diffusion current (il1; il2) at 0.83 and 1.1 V are
60 and 90 mA). These results suggested that the outer two
amine moieties, N-(4-methylphenyl)bis(methoxyphenyl)amines,
were oxidized prior to the inner N-(4-methoxyphenyl)-N-(4-
vinylphenyl)-3-methyl-4-vinylaniline unit.
The triamine 2 was chemically oxidized to the ammoniumyl
cation triradical 2þ with an equivalent amount of thianthre-
niumyl tetrafluoroborate in an acidic mixed solvent of trifluo-
roacetic acid, trifluoroacetic anhydride, and dichloromethane
(vol l7/2/81) (Scheme 2). Upon the oxidation of 2, the solu-
tion color turned deep purple. The ESR spectrum of the 2þ so-
lution had a narrow unimodal signal (g ¼ 2:0029) without any
absorption at g ¼ 2:008 ascribed to the oxidizing agent of the
thianthrene radical. The half-life of the triradical 2þ was esti-
mated by the ESR signal intensity to be ca. 1 week at room
temperature.
Results and Discussion
The content of the ammoniumyl cation radical or spin con-
centration (spin per amine site) in the chemically formed 2þ
The trimer model compound, N-(4-{5-[N,N-bis(4-methoxy-
phenyl)amino]-2-methylstyryl}-3-methylphenyl)-N-(4-{5-[N,N-
bis(4-methoxyphenyl)amino]-2-methylstyryl}phenyl)-4-me-
thoxyaniline (2), was synthesized by coupling of N-(4-methoxy-
phenyl)-N-(4-vinylphenyl)-3-methyl-4-vinylaniline (3) with N,N-
bis(4-methoxyphenyl)-3-bromo-4-methylaniline (4) using the
palladium(II) acetate-tri-o-tolylphosphine catalyst (Scheme 1).
2 was characterized by NMR, IR, and UV–vis spectroscopies.
42 Carbons in the 13C NMR spectrum were ascribed to the
asymmetric structure of 2 composed of three triarylamine moi-
eties and two stilbene bridges. The large coupling constant of
the vinylenes in the 1H NMR spectrum (J ¼ 16 and 16 Hz) and
the IR absorption at ꢁC{H ¼ 963 cmꢁ1 indicated the trans-
vinylene structure for the two stilbene bridges. The UV–vis
absorption (ꢂmax ¼ 302, 387 nm) and fluorescence (ꢂem
¼
502 nm) suggested a developed ꢀ-conjugation in 2.
Cyclic voltammetry of the trimer model compound 2
showed reversible redox waves at 0.72 and 0.84 V (Fig. 2a).
Two oxidation peaks were also observed at 0.70 and 0.85 V
OCH3
OCH3
Fig. 2. Cyclic and differential pulse voltammograms of the
trimer model compound 2 (a), the hyperbranched polymer
6 with DP ¼ 12 (b), 6 with DP ¼ 4 (c), and rotating disk
voltammogram of 2 in CH2Cl2 with 0.1 M (C4H9)4NBF4.
2
N
N
CH3O
CH3
CH3
Br
3
4
OCH3
OCH3
N
CH3
N
N
Pd / P(o-tolyl)3
CH3
S
CH3
N
−
CH3
N
BF4
CH3
CH3
S
2
N
CH3O
OCH3
OCH3
CH3O
OCH3
OCH3
CH3O
CH3O
2+
2
Scheme 1.
Scheme 2.

E. Fukuzaki et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 6 (2006)
955
OCH
OCH
N
3
3
(1) Pd / P(o-tolyl)
3
-ne
1
N
(2)
Br
OCH
3
Ar
n
Br
Br
Ar
5
6
Ar :
OCH
3
Scheme 3.
Fig. 3. ꢃmolT vs T plots for the triradical 2þ (spin concen-
tration = 0.95) ( ) and the polyradical 1 with DP ¼ 12
(spin concentration = 0.65) ( ). The ꢃmolT values were
estimated by the NMR shift method.
was chemically determined by the titration of 2þ with the io-
dide ion of tetrabutylammonium iodide (a chemical quenching
or reduction of the radical with the reductant Iꢁ).30,31 The spin
concentration based on the titration was 0.90 for 2þ (herein
after, the given spin concentration is based on the iodometric
titration of the sample).
The magnetic susceptibility (ꢃmol) of the radical 2þ was
measured using the NMR shift method based on the Evans
equation.32,33 The susceptibility was estimated by taking the
mean of the peak shifts for a concentration series of the stan-
dard peak of cyclohexane in the deuterated C6D6 solution. The
Fig. 4. 1H NMR spectrum of the uncapped polymer 6.
ꢃ
molT value for 2þ at room temperature (303 K) was 0.64
(0.625 for the theoretical value of spin quantum number ðSÞ ¼
3=2). The susceptibility for 2þ was measured in the high tem-
perature range between 303 and 343 K (Fig. 3). The high-spin
and triplet state of the triradical 2þ was maintained even at the
high temperature of 343 K (70 ꢂC). The magnetization of 2þ in
a frozen acidic medium was measured by SQUID. The mag-
netization normalized with saturated magnetization (M=Ms)
vs the ratio of the magnetic field and temperature (H=ðT ꢁ
ꢄÞ) plots for 2þ with a spin concentration of 0.72 were very
close to the theoretical Brillouin curve for S ¼ 2=2 (The spin
concentration remained around 0.7 during sample preparation
for SQUID measurement). The ꢃmolT value vs T plots agreed
with the theoretical value of 0.50 for S ¼ 2=2 and was almost
constant in the temperature range of 20–150 K.
These magnetization data of the ammoniumyl radical 2þ
indicate the chemical stability of the ammoniumyl radical 2þ
and a strong spin-exchange interaction through the branched
and ꢀ-conjugated phenylenevinylene structure, which support
a stable high-spin polymer formation by utilizing the ammo-
niumyl polyradical combined with the phenylenevinylene skel-
eton.
gral ratio of the two vinyl groups was almost unity, indicating a
highly branched polymer structure (a favorable reaction of
either vinyl group yields a linear-type polymer). Bromine was
detected in less than 2 wt % from the elemental analysis.
The head-to-tail linkage and the branched structure in
the polymer 6 were studied by examining a model reaction
(Scheme 4) of N-(4-methoxyphenyl)-N-(4-vinylphenyl)-3-
methyl-4-vinylaniline (3) and bromobenzene using the same
Pd catalyst and condensation reaction conditions. The model
reaction with the feed molecular ratio of bromobenzene/
3 = 1 gave the unreacted terminal unit 3, linear units, N-(4-
methoxyphenyl)-N-(3-methyl-4-vinylphenyl)-4-styrylaniline (7)
and N-(4-methoxyphenyl)-N-(4-vinylphenyl)-3-methyl-4-sty-
rylaniline (70), and the dendritic unit N-(4-methoxyphenyl)-
N-(4-styrylphenyl)-3-methyl-4-styrylaniline (8), as shown in
Scheme 4. The reaction mixture was separated into three frac-
tions by HPLC on a polystyrene-gel column, and the fractions
were analayzed by FAB-mass and 1H NMR spectroscopies.
The FAB-mass peaks [(m=z) 341, 417, and 493 (Mþ)] of the
three fractions agreed with the molecular mass of the unreact-
ed terminal unit 3, the linear units 7 and 70, and the dendritic
unit 8, respectively. The two linear units in the second fraction
could not be separated into 7 and 70. In the 1H NMR spectra of
the two linear units, 7 and 70, the integral ratio of the vinyl
groups decreased in comparison with the ratio for the starting
3 after the reaction. The vinyl group disappeared in the
1H NMR spectrum of the dendritic unit 8 and was converted
into the stilbene structure.
In a previous paper,27 we synthesized the hyperbranched
and head-to-tail linked poly(phenylenevinylene), poly[(4-
methoxyphenyl-N-amino)-1,2(or 4)-phenylenevinylene-1,2(or
4)-phenylene] (6), and reported the room temperature high-
spin state for the corresponding ammoniumyl polyradical 1
1
(Scheme 3). The H NMR spectra of 6 were carefully studied
in this investigation. The peaks in the range of 5.4–5.0 ppm that
resulted from the uncapped polymer could be ascribed to the
two terminal vinyl groups of the polymer 6 (Fig. 4). The inte-
The reaction mixture of the model reaction was analyzed by
NMR to estimate the degree of branching of 6 under this poly-

956 Bull. Chem. Soc. Jpn. Vol. 79, No. 6 (2006)
Quartet Ammoniumyl Triradical
because a Coulomb repulsion between the ammoniumyl cat-
ionic radical in the branched and crowded phenylenevinylene
skeleton decreases the progress of the ammoniumyl cation
formation.
OCH3
Pd / P(o-tolyl)3
N
The hyperbranched polymer 6 was chemically oxidized to
the corresponding ammoniumyl polyradical 1 with an equiva-
lent amount of thianthreniumyl tetrafluoroborate. ꢃmol of the
polyradical 1 was measured by the NMR shift method. The
Br
CH3
3
OCH3
ꢃ
molT value, 0.99, for sample 1 with DP ¼ 12 and a spin con-
N
centration of 0.65 at 25.6 ꢂC (299 K) corresponded to S ¼ 6=2.
The high-spin state of the polyradical 1 was maintained even at
the high temperature of 303–343 K (Fig. 3) as well as that of
the triradical 2þ.
OCH3
CH3
7 (L)
N
3 (T)
OCH3
These results suggested that a multiplet state was observed
for the triradical 2þ and the polyradical 1 even at room temper-
ature based on the very strong spin-exchange interaction be-
tween the unpaired electrons for 1 through the highly hyper-
branched and ꢀ-conjugated poly(phenylenevinylene) skeleton.
CH3
8 (D)
N
CH3
7' (L')
Experimental
Scheme 4.
Synthesis.
amino]-2-methylbenzaldehyde:
4-[N-(4-Formylphenyl)-N-(4-methoxyphenyl)-
4-Bromo-2-methylbenzalde-
hyde (1.93 g, 9.68 mmol), [Pd2(dba)3] (dba: dibenzylideneacetone)
(101 mg, 0.110 mmol), BINAP: 2,20-bis(diphenylphosphino)-
1,10-binaphthalene (206 mg, 0.330 mmol), and Cs2CO3 (4.30 g,
13.2 mmol) were added to a 18 mL toluene solution of 4-[(4-me-
thoxyphenyl)amino]benzaldehyde (2.00 g, 8.80 mmol) in a 50 mL
ampule. The ampule was degassed, sealed, and heated to 100 ꢂC
for 72 h. The resulting mixture was poured into aqueous ammoni-
um chloride, followed by extraction with chloroform, and then the
organic layer was dried over anhydrous magnesium sulfate. After
removal of the solvent, purification by chromatography with a sili-
ca-gel column and chloroform/ethyl acetate = 9/1 as the eluent
gave 4-[N-(4-formylphenyl)-N-(4-methoxyphenyl)amino]-2-meth-
ylbenzaldehyde as a brown oil (1.31 g, Yield 43%). 1H NMR
(CDCl3, 500 MHz) ꢁ 10.10 (s, 1H, formyl), 9.85 (s, 1H, formyl),
7.75 (d, J ¼ 8:8 Hz, 2H, aryl), 7.68 (d, J ¼ 8:5 Hz, 1H, aryl), 7.15
(d, J ¼ 8:8 Hz, 2H, aryl), 7.12 (d, J ¼ 9:0 Hz, 2H, aryl), 7.01 (d,
J ¼ 2:3 Hz, 1H, aryl), 6.94 (d, J ¼ 9:0 Hz, 2H, aryl), 6.92 (d, J ¼
2:3 Hz, 1H, aryl), 3.84 (s, 3H, methoxy), and 2.56 (s, 3H, methyl);
13C NMR (CDCl3, 500 MHz) ꢁ 190.6, 190.2, 157.9, 152.0, 150.9,
142.3, 137.8, 133.5, 131.0, 130.5, 128.9, 128.7, 124.4, 121.7,
119.6, 115.3, 55.3, and 19.6; IR (KBr pellet): 2932 (ꢅAr C{H), 1594
(ꢅC=O), and 1243 cmꢁ1 (ꢅC{O{C); Mass: calcd for M 345.4, found
(m=z) 345 (Mþ). Found: C, 76.4; H, 5.6; N, 4.1%. Calcd for
C22H19NO3: C, 76.5; H, 5.5; N, 4.1%.
Fig. 5. 1H NMR spectrum of the reaction mixture for the
model reaction used to determine the DB.
condensation condition (Fig. 5). The NMR spectrum of the re-
action mixture gave multiple peaks in the range of 5.7–5.1 and
3.8 ppm, which were ascribed to the vinyl and methoxy groups
of each reactant, the terminal unit 3 (T), the linear units 7 and
70 (L and L0), and the dendritic unit 8 (D). The integral ratio of
the vinyl (linear (L + L0)/terminal (T) = 2.02/1) and the me-
thoxy groups (dendritic (D)/linear (L)/terminal (T) = 0.91/
2.08/1) revealed a predominant formation of the dendritic unit
8 in comparison with those of the linear units 7 and 70. The
degree of branching (DB ¼ ðD þ TÞ=ðL þ D þ TÞ ꢃ 2T=ðL þ
2TÞ)34–36 was estimated to be 0.50 and 0.48 based on the vinyl
and methoxy groups, respectively. These results indicated that
the polymer 6 was formed with a highly branched structure
under these experimental conditions.
Cyclic voltammetry of the polymer 6 (Fig. 2b) showed a re-
dox wave with the oxidation peak at 1.0 V and the redox peak
separation of 120 mV at a sweep rate of 100 mV sꢁ1. On the
other hand, the cyclic voltammogram for 6 with the lower
molecular weight of 1700 (degree of polymerization = 4)
(Fig. 2c) gave the unimodal oxidation wave at 0.9 V. The
oxidation potential of the amine moieties of the hyperbranched
polymer 6 probably increased with the molecular weight of 6,
N-(4-Methoxyphenyl)-N-(4-vinylphenyl)-3-methyl-4-vinyl-
aniline (3):
Methyltriphenylphosphonium bromide (6.21 g,
17.4 mmol) was placed in a Schlenk tube, and then dried under
vacuum for 1 h. THF (4.2 mL) was added, and the mixture was
stirred for 10 min at room temperature. A 1.58 M hexane solution
(5.40 mL) of butyllithium (8.69 mmol) was slowly added to the
THF suspension, and then the suspension was stirred for 30 min.
A 5.3 mL of THF solution of 4-[N-(4-formylphenyl)-N-(4-me-
thoxyphenyl)amino]-2-methylbenzaldehyde (600 mg, 1.74 mmol)
was slowly added, and the mixture was stirred for 19 h. The result-
ing mixture was extracted with chloroform, and the organic layer
was dried over anhydrous magnesium sulfate. After removal of
the solvent, purification by chromatography with a silica-gel col-
umn and hexane/chloroform = 4/1 as the eluent gave N-(4-me-
thoxyphenyl)-N-(4-vinylphenyl)-3-methyl-4-vinylaniline (3) as a

E. Fukuzaki et al.
Bull. Chem. Soc. Jpn. Vol. 79, No. 6 (2006)
957
yellow oil (397 mg, Yield 67%). 1H NMR (CDCl3, 500 MHz) ꢁ
7.36 (d, J ¼ 8:2 Hz, 1H, aryl), 7.26 (d, J ¼ 8:0 Hz, 2H, aryl), 7.06
(d, J ¼ 8:8 Hz, 2H, aryl), 6.97 (d, J ¼ 8:8 Hz, 2H, aryl), 6.87 (dd,
J ¼ 11, 17 Hz, 1H, vinyl), 6.85–6.83 (m, 4H, aryl), 6.65 (dd, J ¼
11, 18 Hz, 1H, vinyl), 5.61 (d, J ¼ 18 Hz, 1H, vinyl), 5.55 (d, J ¼
17 Hz, 1H, vinyl), 5.19 (d, J ¼ 11 Hz, 1H, vinyl), 5.13 (d, J ¼ 11
Hz, 1H, vinyl), 3.80 (s, 3H, methoxy), and 2.24 (s, 3H, methyl);
13C NMR (CDCl3, 500 MHz) ꢁ 156.3, 147.7, 147.2, 140.4, 136.4,
136.3, 134.1, 131.2, 130.7, 127.4, 127.0, 126.0, 124.4, 122.6,
120.8, 114.8, 113.3, 111.7, 55.5, and 19.8; IR (KBr pellet):
1242 cmꢁ1 (ꢅC{O{C); Mass: calcd for M 341.5, found (m=z) 341
(Mþ). Found: C, 84.2; H, 5.7; N, 4.0%. Calcd for C24H23NO:
C, 84.4; H, 6.8; N, 4.1%.
2.2 mL of N,N-dimethylformamide solution of N-(4-methoxy-
phenyl)-N-(4-vinylphenyl)-3-methyl-4-vinylaniline (3) (249 mg,
0.73 mmol) in a 5 mL of ampule. The degassed ampule was heated
to 100 ꢂC and stirred for 24 h. The resulting mixture was poured
into aqueous ammonium chloride, followed by extraction with
chloroform, and then the organic layer was dried over anhydrous
magnesium sulfate. After removal of the solvent, purification by
chromatography with a silica-gel column and hexane/chloro-
form = 4/1 as the eluent, and HPLC with a polystyrene-gel col-
umn gave N-(4-{5-[N,N-bis(4-methoxyphenyl)amino]-2-methyl-
styryl}-3-methylphenyl)-N-(4-{5-[N,N-bis(4-methoxyphenyl)ami-
no]-2-methylstyryl}phenyl)-4-methoxyaniline (2) as a yellow sol-
1
id (64.3 mg, Yield 9.0%). H NMR (CDCl3, 500 MHz) ꢁ 7.41 (d,
N,N-Bis(4-methoxyphenyl)-3-bromo-4-methylaniline (4): 2-
Bromo-4-iodotoluene (4.84 g, 16.3 mmol), [Pd2(dba)3] (170 mg,
0.185 mmol), BINAP (346 mg, 0.556 mmol), and sodium t-butox-
ide (2.14 g, 22.2 mmol) were added to a 30 mL of toluene solution
of bis(4-methoxyphenyl)amine (2.00 g, 8.80 mmol) in a 50 mL of
ampule. The degassed ampule was heated to 100 ꢂC and stirred for
72 h. The resulting mixture was poured into aqueous ammonium
chloride, followed by extraction with chloroform, and then the
organic layer was dried over anhydrous magnesium sulfate. After
removal of the solvent, purification by chromatography with a
silica-gel column and hexane/chloroform = 1/1 as the eluent
gave N,N-bis(4-methoxyphenyl)-3-bromo-4-methylaniline (4) as
J ¼ 8:2 Hz, 1H, aryl), 7.31 (d, J ¼ 7:6 Hz, 1H, aryl), 7.21 (s, 1H,
aryl), 7.17 (s, 1H, aryl), 7.11 (d, J ¼ 16 Hz, 1H, vinylene), 7.07–
6.76 (m, 13H, aryl), 7.03(1) (d, J ¼ 8:9 Hz, 8H, aryl), 7.02(6) (d,
J ¼ 16 Hz, 1H, vinylene), 6.88 (d, J ¼ 16 Hz, 1H, aryl), 6.81 (d,
J ¼ 8:9 Hz, 8H, aryl), 6.71 (d, J ¼ 16 Hz, 1H, vinylene), 3.78
(s, 15H, methoxy), 2.33 (s, 6H, methyl), and 2.22 (s, 3H, methyl);
13C NMR (CDCl3, 500 MHz) ꢁ 156.4, 155.4, 155.3, 147.4, 147.0,
146.9(4), 146.9(0), 141.5, 141.4, 140.2, 137.7, 137.2, 136.9,
131.2, 131.0, 130.9, 130.7, 129.4, 128.7, 128.6, 127.6, 127.4,
127.3, 126.4, 126.3, 125.8, 125.7, 124.7, 124.4, 122.7, 121.5,
121.1, 120.9, 119.0, 118.9, 114.8, 114.6, 114.5, 55.5, 21.1, 20.0,
and 19.2; IR (KBr pellet): 1241 (ꢅC{O{C) and 963 cmꢁ1 (ꢁAr C{H);
UV–vis (dichloromethane) ꢂmax ¼ 387 and 302 nm; fluorescent
(dichloromethane) ꢂem ¼ 502 nm (ꢂex ¼ 424 nm); Mass: calcd
for M 976.2, found (m=z) 976 (Mþ). Found: C, 81.4; H, 6.2; N,
4.3%. Calcd for C66H61N3O5: C, 81.2; H, 6.3; N, 4.3%.
The synthesis of the hyperbranched poly[(4-methoxyphenyl-
N-amino)-1,2(or 4)-phenylenevinylene-1,2(or 4)-phenylene] and
the iodometric titration of the ammoniumyl radical have been de-
scribed in a previous paper.27
Other Materials. Tetrabutylammonium tetrafluoroborate and
potassium hexacyanoferrate(III) were purified by recrystallization.
All solvents were purified by distillation just before use. All other
reagents were used as received.
1
a white powder (3.02 g, Yield 51%). H NMR (CDCl3, 500 MHz)
ꢁ 7.43 (s, 1H, aryl), 7.25 (d, J ¼ 8:4 Hz, 4H, aryl), 7.17 (d, J ¼
8:6 Hz, 1H, aryl), 7.04 (d, J ¼ 8:6 Hz, 1H, aryl), 7.02 (d, J ¼
8:4 Hz, 4H, aryl), 3.92 (s, 6H, methoxy), and 2.52 (s, 3H, methyl);
13C NMR (CDCl3, 500 MHz) ꢁ 155.7, 147.7, 140.3, 130.6, 129.0,
126.0, 124.8, 123.9, 119.6, 114.5, 54.9, and 19.8; IR (KBr pellet):
2932 (ꢅAr C{H) and 1240 cmꢁ1 (ꢅC{O{C); Mass: calcd for M 398.3,
found (m=z) 398 (Mþ). Found: C, 63.4; H, 5.0; N, 3.4%. Calcd for
C21H20BrNO2: C, 63.3; H, 5.1; N, 3.5%.
Model Reaction: Bromobenzene (4.60 mg, 29.3 mmol), palla-
dium(II) acetate (0.13 mg, 0.58 mmol), tri-o-tolylphosphine (0.72
mg, 2.4 mmol), lithium chloride (12.4 mg, 0.293 mmol), and trieth-
ylamine (7.15 mg, 70.3 mmol) were added to a 0.15 mL of N,N-
dimethylformamide solution of N-(4-methoxyphenyl)-N-(4-vinyl-
phenyl)-3-methyl-4-vinylaniline (3) (10.0 mg, 29.3 mmol) in a
5 mL of ampule. The degassed ampule was heated to 100 ꢂC and
stirred for 48 h. The resulting mixture was poured into aqueous
ammonium chloride, followed by extraction with chloroform,
and then the organic layer was dried over anhydrous magnesium
sulfate. After removal of the solvent, the mixture was analyzed
by NMR in CDCl3.
Oxidations. Oxidation of the Hyperbranched Polymer 6:
A 11.9 mM thianthreniumyl tetrafluoroborate solution (0.208
mL) of the acidic mixture (dichloromethane/trifluoroacetic acid
(TFA)/trifuluoroacetic anhydride (TFAA) = 97/0.6/2.6 v/v) was
slowly added to a 40.9 mL TFA solution of the polymer 6 (1.00
mg), and stirred for 5 min at room temperature. The reaction mix-
ture turned from yellow to deep purple due to the newly formed
polyradical 1. The resulting mixture was transferred to an ESR
tube (2 mm quartz) or an NMR tube (2 mm glass).
N-(4-Methoxyphenyl)-N-(4-styrylphenyl)-3-methyl-4-styryl-
aniline (8): 1H NMR (CDCl3, 500 MHz) ꢁ 7.51–6.85 (m, 13H,
aryl), 7.38 (d, J ¼ 8:4 Hz, 2H, aryl), 7.31 (d, J ¼ 18 Hz, 1H,
vinylene), 7.25 (d, J ¼ 19 Hz, 1H, vinylene), 7.10 (d, J ¼ 8:8 Hz,
2H, aryl), 7.03(2) (d, J ¼ 19 Hz, 1H, vinylene), 7.02(7) (d, J ¼
8:4 Hz, 2H, aryl), 6.90 (d, J ¼ 18 Hz, 1H, vinylene), 3.82 (s,
3H, methoxy), and 2.33 (s, 3H, methyl); IR (KBr pellet): 2932
(ꢅAr C{H), 1241 (ꢅC{O{C), and 961 cmꢁ1 (ꢁAr C{H); Mass: calcd for
M 493.6, found (m=z) 494 (Mþ).
Oxidation of the Trimer Model Compound 2: A 11.9 mM
thianthreniumyl tetrafluoroborate solution (0.271 mL) in an acidic
mixture (dichloromethane/TFA/TFAA = 97/0.6/2.6 v/v) was
slowly added to a 53.3 mL TFA solution of 2 (1.00 mg, 3.07 mmol),
mol), then stirred for 5 min at room temperature. The reaction
mixture turned from yellow to deep purple as the polyradical 2þ
was produced. The resulting mixture was transferred to an ESR
tube (2 mm quartz), an NMR tube (2 mm glass), or a diamagnetic
capsule for the SQUID measurement.
N-(4-{5-[N,N-Bis(4-methoxyphenyl)amino]-2-methylstyryl}-
3-methylphenyl)-N-(4-{5-[N,N-bis(4-methoxyphenyl)amino]-2-
Electrochemical Measurements.
Voltammetric investiga-
tions were carried out for the samples with a 1 mM/radical unit
in a dichloromethane solution of 0.1 M tetrabutylammonium tetra-
fluoroborate using a BAS 100B/W electrochemical analyzer
(BAS, Inc., Tokyo). Platinum working and Ag/AgCl reference
electrodes were used. The formal potential of the ferrocene/ferro-
cenium couple was 0.43 V vs this reference electrode.
methylstyryl}phenyl)-4-methoxyaniline (2):
N,N-Bis(4-me-
thoxyphenyl)-3-bromo-4-methylaniline (4) (583 mg, 1.46 mmol),
palladium(II) acetate (6.60 mg, 0.0293 mmol), tri-o-tolylphos-
phine (35.7 mg, 0.117 mmol), lithium chloride (61.9 mg, 1.46
mmol), and triethylamine (355 mg, 3.51 mmol) were added to a

958 Bull. Chem. Soc. Jpn. Vol. 79, No. 6 (2006)
Quartet Ammoniumyl Triradical
Kodansha-Wiley, Tokyo and Amsterdam, 2000.
ESR Spectroscopy. The ESR spectrum was recorded by a
JEOL JES-2XG ESR spectrometer. The signal positions were cali-
brated against an external standard of Mn2þ/MgO (g ¼ 1:981).
NMR Magnetic Susceptibilities Measurement. The pre-
pared solution of the radical 2þ or 1 was diluted with the acidic
mixture (CH2Cl2/TFA/TFAA = 81/17/2 v/v) to 9.5, 6.3, and
3.2 mM solutions. A slight amount of cyclohexane was added to
the radical solution for reference. The diluted solution was trans-
ferred to a thin NMR tube (2 mm). The thin NMR tube was placed
in the center of a thick standard NMR tube (a 5 mm glass tube)
filled with a solution of C6D6 and 2 vol % cyclohexane. The chem-
ical shift of cyclohexane for each polyradical solution (9.5, 6.3,
and 3.2 mM) was measured. The peak shift was calibrated with
a blank solution. The ꢃmolT value was calculated from the fre-
quency separation (ꢀꢅ) of cyclohexane between the internal ref-
erence (the radical solution) and the external reference. The
NMR tube for high temperature measurement was sealed to pre-
vent solvent evaporation.
6
7
8
A. Rajca, Chem. Eur. J. 2002, 8, 4834.
A. Rajca, Adv. Phys. Org. Chem. 2005, 40, 153.
K. Matsuda, N. Nakamura, K. Takahashi, K. Inoue, N.
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H. Nishide, T. Kaneko, T. Nii, K. Katoh, E. Tsuchida,
9
P. M. Lahti, J. Am. Chem. Soc. 1996, 118, 9695.
10 Y. Miura, H. Oka, Y. Teki, Bull. Chem. Soc. Jpn. 2001, 74,
385.
11 A. Rajca, J. Wongsriratanakul, S. Rajca, Science 2001,
294, 1503.
12 T. Kaneko, T. Matsubara, T. Aoki, Chem. Mater. 2002, 14,
3898.
13 T. Kaneko, T. Makino, H. Miyaji, M. Teraguchi, T. Aoki,
M. Miyasaka, H. Nishide, J. Am. Chem. Soc. 2003, 125, 3557.
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15 A. Rajca, J. Wongsriratanakul, S. Rajca, J. Am. Chem. Soc.
2004, 126, 6608.
SQUID Measurement. The magnetization and static magnet-
ic susceptibility were measured by a Quantum Design MPMS-7
SQUID magnetometer. The sample solution was transferred to a
diamagnetic capsule. The static magnetic susceptibility was mea-
sured from 1.8 to 200 K in a 0.5 T field. The magnetization was
measured from 0.5 to 7 T at 1.8, 2, 2.5, and 5 K. The quality of
the ferromagnetic impurities and diamagnetic susceptibility of
the matrix and the capsule were determined by the Honda–Owen
and Curie plots, respectively, and were subtracted from the mea-
sured magnetization.
16 S. Rajca, A. Rajca, J. Wongsriratanakul, P. Butler, S. Choi,
J. Am. Chem. Soc. 2004, 126, 6972.
17 E. Fukuzaki, N. Takahashi, S. Imai, H. Nishide, A. Rajca,
Polym. J. 2005, 37, 284.
18 S. Sasaki, M. Iyoda, Mol. Cryst. Liq. Cryst. 1995, 272, 175.
19 T. D. Selby, S. C. Blackstock, J. Am. Chem. Soc. 1995,
121, 7152.
20 F. E. Goodson, S. I. Hauck, J. F. Hartwig, J. Am. Chem.
Soc. 1999, 121, 7527.
21 A. Ito, Y. Ono, K. Tanaka, Angew. Chem., Int. Ed. 2000,
39, 1072.
22 K. Yamamoto, M. Higuchi, S. Shiki, M. Tsuruta, H. Chiba,
Nature 2002, 415, 509.
23 A. Rajca, S. Utamapanya, J. Am. Chem. Soc. 1993, 115,
10688.
24 M. M. Wienk, R. A. J. Janssen, J. Am. Chem. Soc. 1997,
119, 4492.
Other Measurements. The 1H and 13C NMR spectra were re-
1
corded by a JEOL NMR 500 ꢆ. The H and 13C chemical shifts
were referenced to TMS and the signals in the deuterated solvent.
The IR, mass, and UV–vis spectra were measured with JASCO
FT/IR-410, Shimadzu GC-MS 17A, and JASCO V-550 spectrom-
eters. The molecular weight of the polymer was measured by GPC
using a Tosoh LS-8000 (polystyrene gel, THF eluent, polystyrene
calibration). An LC-918 chromatograph (Japan Analytical Indus-
try Co.) was used for the HPLC separation.
25 R. J. Bushby, D. Gooding, J. Chem. Soc., Perkin Trans. 2
1998, 1069.
26 H. Nishide, M. Nambo, M. Miyasaka, J. Mater. Chem.
2002, 12, 3578.
Supporting Information
Data of the NMR shift measurement and SQUID. This material
is available free of charge on the web at http://www.csj.jp/journal/
bcsj/.
27 E. Fukuzaki, H. Nishide, J. Am. Chem. Soc., 2006, 128,
996.
28 M. Jikei, M. Kakimoto, Prog. Polym. Sci. 2001, 26, 1233.
29 B. Voit, J. Polym. Sci., Part A: Polym. Chem. 2000, 38,
2505.
30 N. G. Connelly, W. E. Geiger, Chem. Rev. 1996, 96, 877.
31 L. Eberson, B. Larsson, Acta Chem. Scand., Ser. B 1987,
41, 367.
32 D. F. Evans, J. Chem. Soc. 1959, 2003.
33 F. A. Cotton, C. A. Murillo, X. Wang, Inorg. Chem. 1999,
38, 6294.
This work was partially supported by Grants-in-Aids for the
Priority Area Research (No. 446) ‘‘Super Hierarchical Struc-
tures’’ and for the COE Research Programs ‘‘Practical Nano-
Chemistry’’ and ‘‘Molecular Nano-Engineering’’ from MEXT,
Japan.
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