High-spin polyphenoxyls attached to star-shaped poly(phenylenevinylene)s

Article abstract of DOI:10.1021/jo981090h

Star-shaped poly(1,2-phenylenevinylene)s 4-substituted with multiple pendant phenoxyls (2 and 3) were synthesized by polymerizing 2-bromo-4-(acetoxyphenyl)styrene in the presence of 1,3,5-triiodobenzene or 1,3,5-tris(3′,5′-diiodophenyl)benzene as the core via a simple one-pot Heck reaction and subsequent hydrolysis, phenolate formation, and heterogeneous oxidation. ESR spectra indicated a delocalized spin distribution into the core parts of the star-shaped molecules. The polyradicals, 2 and 3, were in a high-spin state at low temperature, and the ferromagnetic behavior was enhanced for the polyradical with a higher molecular weight. Although an average S of 3 remained at 3/2 to 4/2, the polyradical 2 even with a spin concentration of 0.8 spin/unit revealed an average S of 7/2 to 8/2. The 1,3,5-benzene core acted as an effective magnetic coupler to align the spins of the pendant phenoxyls through the star-shaped π-conjugated backbone.

Full text of DOI:10.1021/jo981090h

J . Org. Chem. 1998, 63, 7399-7407
7399
High -Sp in P olyp h en oxyls Atta ch ed to Sta r -Sh a p ed
P oly(p h en ylen evin ylen e)s
Hiroyuki Nishide,* Makoto Miyasaka, and Eishun Tsuchida
Department of Polymer Chemistry, Waseda University, Tokyo 169-8555, J apan
Received J une 8, 1998
Star-shaped poly(1,2-phenylenevinylene)s 4-substituted with multiple pendant phenoxyls (2 and
3) were synthesized by polymerizing 2-bromo-4-(acetoxyphenyl)styrene in the presence of 1,3,5-
triiodobenzene or 1,3,5-tris(3′,5′-diiodophenyl)benzene as the core via a simple one-pot Heck reaction
and subsequent hydrolysis, phenolate formation, and heterogeneous oxidation. ESR spectra
indicated a delocalized spin distribution into the core parts of the star-shaped molecules. The
polyradicals, 2 and 3, were in a high-spin state at low temperature, and the ferromagnetic behavior
was enhanced for the polyradical with a higher molecular weight. Although an average S of 3
remained at 3/2 to 4/2, the polyradical 2 even with a spin concentration of 0.8 spin/unit revealed
an average S of 7/2 to 8/2. The 1,3,5-benzene core acted as an effective magnetic coupler to align
the spins of the pendant phenoxyls through the star-shaped π-conjugated backbone.
In tr od u ction
romagnetic spin-coupling interaction between the pen-
dant unpaired electrons.4 The polyradical 1 with a spin
concentration of 0.7 spin/monomer unit or /phenoxy
precursor group displayed a spin quantum number (S)
at low temperature of 4/2 to 5/2.
The research on very high-spin organic molecules using
intramolecular through-bond magnetic ordering has been
exhaustively continued in connection with realizing
purely organic-derived and unknown magnetism.1,2
Among these efforts, there is an approach to design and
synthesize a π-conjugated linear polymer bearing mul-
tiple pendant radical groups, which are attached to one
π-conjugated backbone that satisfies a ferromagnetic
connectivity of the radicals.3 In this type of polyradical,
a radical or spin defect, which is unavoidable for radical
polymers with an increase in molecular size, is not fatal
to the spin alignment between the pendant unpaired
electrons, because the spin-coupling interaction occurs
through the π-conjugated polymer backbone. Addition-
ally, multiple numbers of spin are accumulated along one
backbone, and the spins are expected to interact among
not only their neighboring spins but also their remote
spins through the π-conjugated backbone. Besides these
advantages, a chemically stable organic radical species
can be introduced on a polyradical as the pendant group.
The resultant polyradical has substantial stability and
is easily handled, e.g., at room temperature. We recently
synthesized poly(1,2-phenylenevinylene) bearing di-tert-
butylphenoxyl as the pendant radical group (1) because
of the coplanarity in the π-conjugated linear backbone
and of the delocalized spin density distribution of the
radical moiety, and we have for the first time reported a
through-conjugated backbone bond and long-range fer-
Prior to and parallel with the approach using pendant-
type polyradicals, high-spin alignment at low tempera-
ture has been demonstrated for cross-conjugated polyrad-
icals such as poly(1,3-phenylenecarbene)1b and poly(1,3-
phenylenephenylmethine).1c They have been recently
extended to their (pseudo-)two-dimensional homologues,
i.e. branched, dendric, macrocyclic, annelated macrocy-
clic, and pseudo-ladder polyradicals.2,5 Such two-dimen-
sional extensions successfully brought about the increase
in S; the extensions, especially the macrocyclic ones,
diminished the damage of a spin defect by guaranteeing
plural pathways of the spin-coupling interaction in the
two-dimensional frameworks. A spin defect is fatal for
the cross-conjugated polyradicals because their radicals
are formed in the backbone through cross-conjugated
structures and a spin defect breaks down their π-conju-
gation. In addition to this problem, these carbon-
centered polyradicals are far too unstable to make a
practicable material. To improve such a two-dimensional
strategy for organic polyradicals with high spin align-
ment, we extended in this paper6 our pendant-type
polyradical 1, which is characterized by chemical stability
and spin-defect-insensitivity, to the star-shaped homo-
logues, 2 and 3, star-shaped poly(1,2-phenylenevinylene)s
bearing 4-substituted pendant phenoxyl radicals.
Resu lts a n d Discu ssion
(1) For reviews on high-spin organic molecules, see: (a) Dougherty,
D. A. Acc. Chem. Res. 1991, 24, 88. (b) Iwamura, H.; Koga, N. Acc.
Chem. Res. 1993, 26, 346. (c) Rajca, A. Chem. Rev. 1994, 94, 871. (d)
Miller, J . S.; Epstein, A. J . Angew. Chem., Int. Ed. Engl. 1994, 33,
385.
Syn th esis a n d Ch a r a cter iza tion of th e P r ecu r sor
Sta r -Sh a p ed P olyp h en ols. A restricted primary struc-
(2) For recent papers on high-spin organic molecules, see: (a) Rajca,
A.; Lu, K.; Rajca, S. J . Am. Chem. Soc. 1997, 119, 10355. (b) Rajca, A.;
Wongsriratanakul, J .; Rajca, S. J . Am. Chem. Soc. 1997, 119, 11674.
(c) Ruiz-Molina, D.; Veciana, J .; Palacio, F.; Rovira, C. J . Org. Chem.
1997, 62, 9009. (d) Bushby, R. J .; McGill, D. R.; Ng, M. K.; Taylor, N.
J . Mater. Chem. 1997, 7, 2343.
(3) (a) Nishide, H.; Yoshioka, N.; Inagaki, K.; Tsuchida, E. Macro-
molecules 1988, 21, 3119. (b) Nishide, H.; Yoshioka, N.; Kaneko, T.;
Tsuchida, E. Macromolecules 1990, 23, 4487. (c) Nishide, H. Adv.
Mater. 1995, 7, 937. (d) Nishide, H. In Molecular-Based Magnetic
Materials; Turnbull, M. M., Sugimoto, T., Thompson, L. K., Eds.; ACS
Symp. Ser. 644; 1996; pp 247-257.
(4) (a) Nishide H.; Kaneko, T.; Nii, T.; Katoh, K.; Tsuchida, E.;
Yamaguchi, K. J . Am. Chem. Soc. 1995, 117, 548. (b) Nishide H.;
Kaneko, T.; Nii, T.; Katoh, K., Tsuchida, E.; Lahti, P. M. J . Am. Chem.
Soc. 1996, 118, 9695.
(5) (a) Rajca, A.; Utamapanya, S. J . Am. Chem. Soc. 1993, 115,
10688. (b) Nakamura, N.; Inoue, K.; Iwamura, H. Angew. Chem., Int.
Ed. Engl. 1993, 32, 872. (c) Rajca, A.; Rajca. S.; Desai, S. R. J . Am.
Chem. Soc. 1995, 117, 806. (d) Rajca, A.; Wongsriratanakul, J .; Rajca,
S.; Cerny, R. Angew. Chem., Int. Ed. Engl. 1998, 37, 1229.
(6) For
a preliminary communication paper, see: Nishide, H.;
Miyasaka, M.; Tsuchida, E. Angew. Chem., Int. Ed. Engl., 1998, 37,
2400.
S0022-3263(98)01090-1 CCC: $15.00 © 1998 American Chemical Society
Published on Web 10/01/1998

7400 J . Org. Chem., Vol. 63, No. 21, 1998
Nishide et al.
Ta ble 1. Molecu la r Weigh t of th e Hyd r oxy P olym er s
a n d Aver a ge Sp in Qu a n tu m Nu m ber of th e P olyr a d ica ls
ture or complete head-to-tail linkage of the monomer unit
is essential for a ferromagnetic spin alignment in the
pendant-type polyradical, which was established in this
study through the polymerization via the Heck reaction,7
or the arylation of an olefin with an aryl bromide
catalyzed by a palladium-phosphine complex, of a bro-
mostyrene derivative, 2-bromo-4-(3′,5′-di-tert-butyl-4′-
acetoxyphenyl)styrene (4).4 The acetoxy polymer 6 was
synthesized through a one-pot reaction of 4 via the Heck
reaction using a catalyst of palladium acetate and tri-o-
tolylphosphine, in the presence of 1,3,5-triiodobenzene
(5) as the core of the star-shaped polymer. 5 was selected
as the core because of its higher reactivity in the Heck
reaction than 4. In addition, a strong ferromagnetic
coupling effect of the 1,3,5-benzene ring has been re-
ported for 1,3,5-tris(di-p-biphenylmethyl)benzene,8a 1,3,5-
tris(3′,5′-tert-butyl-4′-oxyphenyl)benzene,8b and 1,3,5-
benzenetriyltris(N-tert-butylnitroxide).8c The iodide of 5
was initially and completely reacted with 4 at 45 °C, and
heating to 90 °C allowed the reaction of the bromide of 4
to yield the phenylenevinylene polymer. The molecular
weight or degree of polymerization (DP, )l + m + n in
2) of the star-shaped polymer was controlled by the feed
ratio of 4/5 in the polymerization.
hydroxy yield
Mwd/ poly- spin concn
polymer (%)a mol wtb (DPc) Mn radical (spin/unit)
Se
7
7
7
12′
11′
1′
15
18′
42
45
48
2.1 × 104 (70) 1.2
1.3 × 104 (42) 1.2
1.0 × 104 (33) 1.2
1913 (6)
2
2
2
12
11
1
0.80
0.70
0.72
0.83
0.91
0.68
0.63
0.88
7/2 to 8/2
6/2 to 7/2
5/2 to 6/2
4/2 to 5/2
3/2
4/2 to 5/2
3/2 to 4/2
2/2
996 (3)
40
62
5.7 × 103 (17) 1.2
1.1 × 104 (34) 1.2
2142 (6)
3
18
a
Yield for the polymerization of the precursor acetoxy polymer.
Average molecular weight measured by the light-scattering
b
method for 7, 1′, and 15, and molecular weight measured by mass
spectroscopy for 12′, 11′, and 18′. c Average degree of polymeri-
zation for 7, 1′, and 15, and number of hydroxyphenylstyrene units
represented in Schemes 2 and 4 for 12′, 11′, and 18′, respectively.
d
Ratio of the number- and weight-average molecular weight
measured by gel-permeation chromatography. e Average spin quan-
tum number for the spin state at 2-5 K.
green powder which was chemically stable at room
temperature even in air. For example, the half-life of
the radical in 2 was 3.4 days at room temperature.
As core-combined tri- and hexaradical compounds,
their precursors, 1,3,5-tris[4′-(3′′,5′′-di-tert-butyl-4′′-ac-
etoxyphenyl)styryl]benzene (11′) and 1,3,5-tris[2′-styryl-
{4′,5′′-bis(3,5-di-tert-butyl-4-acetoxyphenyl)stilbene}]-
benzene (12′), were also synthesized via the same
palladium-catalyzed Heck reaction.
The polyradicals having six π-conjugated branch chains
3 were also synthesized from the core of 1,3,5-tris(3′,5′-
diiodophenyl)benzene (13). 13 was prepared via benzene
ring formation of 3,5-diiodoacetophenone. In the pres-
ence of 13, 4 was polymerized using the palladium-
phosphine catalyst at 45 °C and then 90 °C in a similar
manner for the 6 synthesis already described. The six
iodo sites of 13 were completely reacted with 4. The ace-
toxy polymer 14 was a yellow powder, soluble in common
solvents, and was characterized, in the same manner for
6 (for details, see Experimental Section). 14 was com-
pletely hydrolyzed to the hydroxy polymer 15 (Table 1).
15 was converted to the corresponding phenolate polymer
16 through alkaline treatment and was then heteroge-
neously oxidized to yield the polyradical 3. The brownish
green 3 was also soluble in common solvents such as
benzene, THF, and CHCl3. The half-life of the radical
was 1.4 days for 3 in powder state at room temperature.
The 6 polymers were obtained as yellow powders that
were soluble in common solvents such as benzene, THF,
and CHCl3. The iodo site of the core 5 was completely
reacted in every polymer, which was confirmed by the
iodine content of less than 0.01% determined by the
combustion method and X-ray fluorometry. Fourteen
aromatic carbon absorption peaks in 13C NMR ascribed
to the benzene rings and vinylene supported both the
head-to-tail linkage structure of the branch chains and
vinylene-substituted benzene structure of the core (for
details, see Experimental Section). The trans-stilbene
structure was supported by fluorescence at 450 nm (λex
) 420 nm) and IR absorption attributed to an out-of-
plane bending mode of the trans-vinylene at 960 cm-1
.
The precursor acetoxy polymer 6 was converted to the
corresponding hydroxy polymer 7 after complete elimina-
tion of the protecting acetyl group in alkaline solution.
DP was measured by a light-scattering molecular weight
analysis; e.g., 7 with DP ) 70 determined by the light-
scattering analysis and DP ) 68 by bromide analysis (for
details, see Experimental Section). The agreement in the
DP values supports a linear structure of the branch
chains. Three hydroxy polymers 7 with different DP or
molecular weight were synthesized (Table 1).
The hydroxy polymer 7 was converted to a deeply red-
colored phenolate anion of the polymer (8) with a small
excess of tetra(n-butyl)ammonium hydroxide in THF.
Quantitative formation of the phenolate anion 8 was
detected by a complete disappearance of 6.2 ppm ascribed
to the phenolic proton in NMR of the THF-d8 solution of
7 under the constant integration values of aromatic and
tert-butyl protons, after alkaline addition to the 7 THF
solution. 8 was heterogeneously oxidized with an aque-
ous K3FeCN6 phase to yield the polyradical 2. 2 was also
soluble in common solvents. 2 was isolated as a brownish
The 1,3,5-triphenylbenzene-combined hexaradical com-
pound 18 was also synthesized by the same Heck reaction
of 9 with 1,3,5-tris(3′,5′-dibromophenyl)benzene.
ESR Sp ectr a of th e P olyr a d ica ls. The ESR spectra
of 2 and 3 at a low spin concentration (spin concn) gave
a broad hyperfine structure at g ) 2.0042 attributed to
the 5-7 protons of the phenoxyl ring and phenylenevi-
nylene backbone, which was in contrast to the three-line
hyperfine structure of 2,4,6-tri-tert-butylphenoxyl or that
attributed to an unpaired electron localized in the phe-
noxy ring. The proton hyperfine structures were more
clearly observed for the core-combined triradical and
hexaradical models, 11 and 18, at a low spin concn
(Figure 1a,b, respectively). The dashed line of Figure 1a
shows a simulation of the hyperfine structure for 11,
which gave the aH values of 0.09 mT attributed to the
vinylene protons and those of 0.08 mT attributed to the
protons of the 1,3,5-trisubstituted benzene core. These
ESR results suggest an effectively delocalized spin dis-
(7) (a) Heck, R. F. Org. React. 1982, 27, 345. (b) Greiner, A.; Heitz,
W. Makromol. Chem. Rapid Commun. 1988, 9, 581.
(8) (a) Schmauss, G.; Baumgaertel, H.; Zimmermann, H. Angew.
Chem., Int. Ed. Engl. 1965, 4, 596. (b) Kothe, G.; Nowak, C.; Denkel,
K.-H.; Ohmes, E.; Zimmermenn, H. Angew. Chem., Int. Ed. Engl. 1970,
9, 520. (c) Kanno, F.; Inoue, K.; Koga, N.; Iwamura, H. J . Phys. Chem.
1993, 97, 13267.

High-Spin Polyphenoxyls
J . Org. Chem., Vol. 63, No. 21, 1998 7401
F igu r e 2. Curie plots for the peak in the ∆Ms ) (2 region
for the polyradical 2 with spin concn ) 0.70 spin/unit in
toluene glass. Phenoxy precursor concn ) 30 unit mM. Inset:
∆Ms ) (2 spectrum.
F igu r e 1. ESR spectra of the tri- and hexaradicals at room
temperature. Phenoxy precursor concn ) 0.5 unit mM. (a)
Triradical 11 with spin concn ) 0.08 in toluene at g ) 2.0042;
the dashed line for the simulation with aH ) 0.10, 0.09, and
0.08 mT. (b) Hexaradical 18 with spin concn ) 0.12 in toluene
at g ) 2.0042; aH for the simulation with 0.10, 0.09, and 0.08
mT.
tribution over the entire star-shaped polyradical 2 prob-
ably because of its less hindered steric structure. The
hyperfine structure for 18 (Figure 1b) resembles that for
11; a simulation gave the aH values of 0.09 mT attributed
to the vinylene protons and those of 0.08 mT attributed
to the protons of the outer 1,3,5-benzene ring substituted
with two branch phenoxyls and one core benzene. How-
ever, any further splitting to be ascribed to the protons
of the core benzene was not observed. These results
suggest for the hexaradical model 11 a spin density
distribution into the outer three benzene rings from the
branch polyphenoxyl chains but not into the core benzene
or the inner part of the core.
The ESR spectra of 2 and 3 showed sharp and unimo-
dal signals with increasing spin concn, indicating a locally
high spin concn along the polymer backbones. A frozen
toluene glass of 2 with a spin concn of 0.7 spin/unit gave
a ∆Ms ) (2 forbidden transition ascribed to a triplet
species at g ) 4 (inset in Figure 2). The ESR signal in
the ∆Ms ) (2 region was doubly integrated to give Curie
plots (Figure 2). Although the signal intensity is pro-
portional to the reciprocal of the temperature (1/T) at
higher temperature, the plots deviate upward from
linearity in the lower temperature (<35 K) region. This
upward deviation supports a multiplet ground state for
the polyradical 2.
F igu r e 3. Normalized plots of magnetization (M/ Ms) vs the
ratio of magnetic field and temperature (H/ (T - θ)) for the
polyradical 2 with DP ) 70 and a spin concn ) 0.80 spin/unit
in frozen 2Me-THF at T ) 1.8 (b), 2.0 (9), 2.5 (O), and 3 (0)
K, and the theoretical curves corresponding to the S ) 1/2,
2/2, 3/2, 4/2, 5/2, 6/2, 7/2, 8/2, 9/2, and 10/2 Brillouin functions.
Inset: M/ Ms vs H/ (T - θ) plots (closed) for the hexaradical
12 with spin concn ) 0.83 spin/unit at T ) 2.0 (b), 2.5 (9), 3.0
([), and 5.0 (2) K; the plots (open) for the triradical 11 with
spin concn ) 0.91 spin/unit at T ) 2.0 (O), 2.5 (0), 3.0 (]),
and 5.0 (4) K; and the theoretical curves corresponding to the
S ) 1/2, 2/2, 3/2, 4/2, 5/2, and 6/2 Brillouin functions.
of a weak antiferromagnetic interaction between radicals
and is determined from curve fitting using the following
ømolT vs T data. The M/ Ms plots are compared with the
theoretical Brillouin curves for S ) 1/2 to 10/2. It should
be noted here that, for a disperse spin system, an
“average” Brillouin function is never followed in a strict
manner for monodisperse spin systems and that the
M/ Ms tends to decrease at high fields due to lower S
fragments such as S ) 1/2, 2/2, and 3/2, as has been
previously discussed.5a The M/ Ms plots of the polyradical
2 are close to the Brillouin curves for S ) 9/2 at low fields
and lie almost on the curve for S ) 6/2 at high fields.
This indicates a ferromagnetic coupling, on the average,
between seven or eight unpaired electrons at low tem-
perature. The magnetization plots for 2 with DP ) 42
and 33 were also measured and compared with the
Brillouin curves to give the average S values in Table 1.
The inset in Figure 2 shows the M/ Ms plots for 12 with
a spin concn ) 0.83 and 11 with a spin concn ) 0.91,
which indicate that S ) 4/2 to 5/2 and 3/2 at low
temperature for 12 and 11, respectively. The latter
Magn etic P r oper ties. Magnetization and static mag-
netic susceptibility of the polyradicals 2, 11, and 12, in
frozen 2Me-THF or toluene, were measured using a
SQUID magnetometer. The magnetization (M) normal-
ized with saturated magnetization (Ms) for 2 with DP )
70 and spin concn ) 0.80 is plotted vs the effective
temperature (T - θ) (Figure 3), where θ is a coefficient

7402 J . Org. Chem., Vol. 63, No. 21, 1998
Nishide et al.
triplet, and the quartet, respectively (x1 + x2 + x3 ) 1).
The ømolT data of 11 in Figure 4 were analyzed (the solid
line in Figure 4 is curve-fitted to eq 1) to give 2J ) 19 (
2 cm-1 for 11. This exchange coupling constant is larger
than that for the biradical analogue of the branch
polyphenoxyl chain (19), which also involves the conju-
gated but spacing phenylenevinylene unit. This result
supports the fact that the 1,3,5-benzene core acts as an
effective coupler to connect three branch polyradical
chains.
The M/ Ms plots of the hexaradical 18 with spin concn
) 0.88 lay almost on the Brillouin curve for S ) 2/2; the
hexaradical 18 remained at a triplet ground state. The
ø
molT vs T plots of 18 are given in the inset in Figure 5
F igu r e 4. ømolT vs T plots (b) of the polyradical 2 with DP )
70 and spin concn ) 0.80 spin/unit, (O) of the triradical 11
with spin concn ) 0.91 spin/unit, and (0) of the biradical 19
with spin concn 0.72 spin/unit in frozen 2Me-THF. Solid lines
are theoretical curves calculated using eq 1 for 11 (2J ) 19
cm-1, θ ) -0.29 K, x1 ) 0, x2 ) 0.13, x3 ) 0.87) and using the
Bleany-Bowers expression for 19 (2J ) 6 cm-1, x1 ) 0.34, x2
) 0.66).
and were analyzed using eq 1 (the solid line for curve
fitting) to yield 2J ) 19 ( 3 cm-1. This 2J value agrees
with that for the triradical 11 and supports the spin-
coupling interaction of two phenoxyls through the same
conjugated spacer of phenylenevinylene-m-phenylene-
vinylenephenylene for both 18 and 11 (see Schemes 2 and
4). However, 18 did not display any effect of the inner
core of the 1,3,5-benzene coupler on the S and 2J value
or the ferromagnetic coupling interaction.
indicates a quartet ground state of the triradical 11.
These results mean that the 1,3,5-substituted benzene
acts as an effective coupler to connect three branch
polyradical chains.
The inset of Figure 5 also shows the ømolT data for the
hexabranched polyradical 3 with DP ) 34 and spin concn
) 0.63. ømolT and its increase at low temperature were
larger than those of the hexaradical 18. However, the
M/ Ms plots of the polyradical 3 remained almost on the
Brillouin curve of S ) 3/2 (Figure 5). The hexabranched
extension based on the core of 1,3,5-tris(3′,5′-disubsti-
tuted phenyl)benzene failed in increasing the S value or
the spin-coupling interaction between the phenoxyls
attached to the star-shaped π-conjugated backbone.
Figure 4 shows the product of molar magnetic suscep-
tibility (ømol) and T vs T for the polyradicals 2 (DP ) 70,
spin concn ) 0.80).
ømolT is much larger than the
theoretical value (ømolT ) 0.375) for S ) 1/2 and increases
at low temperature, which indicates a strong ferromag-
netic behavior. The ømolT increase at low temperature
was decreased for the polyradical 2 with a lower molec-
ular weight. The figure also gives the ømolT plots for the
core-combined triradical 11 and the biradical analogue
of 1 or of the branch polyphenoxyl chain (19 in Chart 2).
They exhibit not a strong but a ferromagnetic ømolT
increase.
In the polyradical 3, the inner core benzene could not
magnetically couple the outer-phenyl-substituted six
polyphenoxyl branch chains, despite the totally π-conju-
gated primary structure of 3. Two reasons are considered
for this insufficient connectivity between the three outer-
phenyl rings and the inner or central 1,3,5-benzene ring.
(i) Biphenyl is not a strong magnetic coupler because of
the twisted and noncoplanar biphenyl linkage. In addi-
tion, the 3′-outer-phenyl-substituted branch chains steri-
cally hinder the branch chains 5′-substituted on the
neighboring outer phenyls for 3 and 18. (ii) Borden and
Davidson proposed a concept of disjoint and nondisjoint
connectivity of nonbonding molecular orbitals (NBMOs)
to estimate the stability of a triplet ground state of a
biradical molecule.11 By applying this concept to the core
of 3 and 18, 1,3,5-tris(3′,5′-diradical-substituted phenyl)-
benzene (Chart 3), the NBMOs cannot be localized in
disjoint groups (i.e., nondisjoint), and a triplet ground
state is stabilized with sufficient 2J for the biradical part
connected with the phenylenevinylene-m-phenylene-
vinylenephenylene or the pair of polyphenoxyl branch
chains 3′,5′-substituted on the outer-phenyl ring. How-
ever, the NBMOs are confinable to separate regions at
the biphenyl linkage or between the inner 1,3,5-benzene
core and the outer-phenyl rings, and a reduced exchange
interaction between unpaired electrons in the biradical
through the inner central core minimizes the stability of
a multiplet ground state.
The M/ Ms plots of 19 were presented close to the
Brillouin curve for S ) 2/2 at low temperature, indicating
a triplet ground state of the biradical 19. ømolT vs T plots
of 19 in Figure 4 were analyzed using the Bleaney-
Bowers expression9 to estimate the spin-exchange cou-
pling constant (J ) in the biradical. Curve fitting of the
ø
molT data for 19 in Figure 4 (the solid line) yielded the
exchange coupling constant or a triplet-singlet energy
gap 2J ) 6 ( 1 cm-1 (other parameters given in the
caption of Figure 4). The triradical 11 with S e 3/2 could
be expressed as the mixture of a three-, two-, and one-
spin system, and its ømolT could be analyzed, as a first
approximation, using the following van Vleck expression:
10
NAg2µB T
2
ø
molT )
k(T - θ)
x3
1 + exp(-2J /kT) + 10 exp(J /kT)
1 + exp(-2J /kT) + 2 exp(J /kT)
+
+
[
12
x2
x1
(1)
]
4
3 + exp(-2J /kT)
where x1, x2, and x3 are the fraction of the doublet, the
(9) Bleaney, B.; Bowers, K. D. Proc. R. Soc. London 1952, A214, 451.
(10) Vleck, J . H. V. The Theory of Electric and Magnetic Suscepti-
bilities; Oxford University Press: London, 1932.
(11) Borden, W. T.; Davidson, E. R. J . Am. Chem. Soc. 1997, 99,
44587.

High-Spin Polyphenoxyls
J . Org. Chem., Vol. 63, No. 21, 1998 7403
Ch a r t 1
logues, 2 and 3, through a simple one-pot polymerization.
The polyradicals were chemically stable and easily
handled even at room temperature. The three-branched
polyradical 2 based on the core of 1,3,5-benzene displayed
an average S of 7/2 to 8/2, while S remained at 3/2 to 4/2
for the six-branched polyradical 3 based on 1,3,5-tris(3′,5′-
disubstituted phenyl)benzene. A simple coupler of 1,3,5-
benzene was sufficient to ferromagnetically connect the
polyphenoxyl branch chains. The high-spin state of 2 at
low temperature was not sensitive to a spin defect in 2,
and S increased with the molecular size of 2. Because 2
still possesses the bromide sites at the end of each branch
chain, it can be effectively used for the purpose of
synthesizing a three-dimensional and starburst-shaped
further extension of the high-spin polyphenoxyl.
F igu r e 5. M/Ms vs H/(T - θ) plots of the polyradical 3 with
DP ) 34 and spin concn ) 0.63 spin/unit in frozen 2Me-THF
at T ) 1.8 (b), 2.0 (9), 2.5 (O), 3 (0), and 5 (]) K, and the
theoretical curves corresponding to the S ) 1/2, 2/2, 3/2, 4/2,
and 5/2 Brillouin functions. Inset: ømolT vs T plots (b) of the
polyradical 3 and (O) of the hexaradical 18 with spin concn )
0.88 spin/unit in frozen 2Me-THF. Solid line is a theoretical
curve calculated using eq 1 for 18 (2J ) 19 cm-1, θ ) -0.05
K, x1 ) 0.39, x2 ) 0.61, x3 ) 0).
Exp er im en ta l Section
1,3,5-Tr iiod oben zen e (5). 5 was prepared via the direct
iodination of p-nitroaniline, deamination, reduction of the nitro
group, and diazoiodination: mp 183 °C (184 °C in lit.12); MS
(m/z), 455 (M+), calcd for M ) 455.8; 1H NMR (CDCl3, 500
MHz; ppm) δ 7.00 (s, 3H, phenyl); 13C NMR (CDCl3, ppm) δ
95.20, 144.42.
1,3,5-Tr is[p oly(4-(3′,5′-d i-ter t-bu tyl-4′-a cetoxyp h en yl)-
1,2-p h en ylen evin ylen e)]ben zen e (6). Palladium acetate
(138 mg, 0.6 mmol), tri-o-tolylphosphine (375 mg, 1.2 mmol),
triethylamine (3.12 g, 3.08 mmol), and 5 (46.0 mg, 0.1 mmol)
were added to a DMF solution (12.3 mL) of the 2-bromo-4-
(3′,5′-di-tert-butyl-4′-acetoxyphenyl)styrene (4) (see ref 5) (2.6
g, 6.06 mmol) (molar feed ratio 4/5 ) 60). The solution was
warmed at 45 °C for 6 h and then heated to 90 °C for 18 h.
The mixture was separated using a polystyrene-gel column
with CHCl3 eluent and was purified by reprecipitation from
CHCl3 in methanol to yield the polymer as a yellow powder:
yield 42%; IR (KBr pellet, cm-1) 1765 (νCdO), 960 (δtransHCdCH);
1H NMR (CDCl3, 500 MHz; ppm) δ 1.35 (s, 54H, tert-butyl),
2.32 (s, 9H, -O-CO-CH3), 7.03-8.08 (m, 24H, Ar, CHdCH);
13C NMR (CDCl3, ppm) δ 22.53 (CH3), 31.98, 36.20 (t-Bu),
125.85, 127.40, 127.72, 128.05, 129.18, 129.39, 132.11, 135.97,
137.66, 138.45, 138.67, 142.17, 143.68, 147.68 (aromatic),
170.76 (Ac). The 14 peaks based on aromatic carbons were
assigned to the small latter numbers 3, 12, 11, 6, 8, 7, 13, 2,
Ch a r t 2
Con clu sion
Pendant-type polyphenoxyl attached to poly(1,2-phe-
nylenevinylene) 1 was extended to star-shaped homo-
(12) Willgerodt, A. Berichte. 1901, 34, 3347.

7404 J . Org. Chem., Vol. 63, No. 21, 1998
Nishide et al.
Sch em e 1
Sch em e 2
4, 14, 10, 9, 5, and 1, respectively, in 6 in Chart 4. Anal. Calcd
for (C24nH28nBr3O2n)C6H3 (n ) 68): C, 81.97; H, 7.95; Br, 1.00.
Found: C, 81.95; H, 7.92; Br, 1.00; I, <0.01. The polymeri-
zation was carried out under the 4/5 feed ratio of 45 or 30 to
obtain the polymer with a different molecular weight: yield
45 and 48%, respectively (see Table 1).
The protecting trimethylsilyl group was then changed to an
acetyl group, and the methyl group was converted to a vinyl
group via a Wittig reaction: total yield 35%; IR (KBr pellet,
cm-1) 1755 (νCdO), 1628 (δCdC); 1H NMR (CDCl3, 500 MHz;
ppm) δ 1.42 (s, 18H tert-butyl), 2.37 (s, 3H, -O-CO-CH3),
5.25 (d, 1H, 10 Hz, -CHdCH2), 5.77 (d, 1H, 17 Hz, -CHd
CH2), 6.75 (dd, 1H, 10 Hz, 17 Hz, -CHdCH2), 7.21-7.52 (m,
6H, Ar, CHdCH); 13C NMR (CDCl3, ppm) δ 22.70, 31.48, 35.54,
113.76, 125.25, 126.52, 127.40, 136.39, 136.42, 137.82, 141.00,
142.55, 147.56, 171.14; MS (m/z) 350 (M+), calcd for M ) 350.2.
1,3,5-Tr is[p oly(4-(3′,5′-d i-ter t-bu tyl-4′-h yd r oxyp h en yl)-
1,2-p h en ylen evin ylen e)]ben zen e (7). 6 (207 mg) was dis-
solved in a small amount of THF. To its suspension in DMSO
(47 mL) was added 2.5 N KOH (2.3 mL), and the solution was
stirred at 40-50 °C for 12 h, cooled to room temperature, and
neutralized with 1 N HCl. The organic product was extracted
with CHCl3, washed with water, and dried over anhydrous
sodium sulfate. The CHCl3 layer was evaporated and poured
in methanol to yield 7: yield 48%; IR (KBr pellet, cm-1) 3640
(νO-H), 960 (δtransHCdCH); 1H NMR (CDCl3, 500 MHz; ppm) δ
1.45 (s, 54H tert-butyl), 5.24 (s, 3H, OH), 7.39-7.78 (m, 24H,
Ar, CHdCH); 13C NMR (CDCl3, ppm) δ 29.85, 33.96, 123.43,
123.55, 126.25, 126.51, 126.78, 127.64, 128.12, 131.66, 133.68,
134.72, 135.78, 136.12, 141.44, 153.17. The molecular weight
of the polymer was measured by a light-scattering molecular
weight analyzer (Tosoh LS-8000): mol wt ) 2.1 × 104 (DP )
70). Anal. Calcd for (C22nH26nBr3On)C6H3 (n ) 68): C, 85.33;
H, 8.38; Br, 1.14. Found: C, 85.29; H, 8.42; Br, 1.14; I, <0.01.
2-Vin yl-5,4′-bis(3,5-d i-ter t-bu tyl-4-a cetoxyp h en yl)stil-
ben e (10). 2-Methyl-5,4′-bis(3,4-di-tert-butyl-4′-acetoxyphe-
nyl)stilbene was prepared by coupling 2-bromo-4-(3′,5′-di-tert-
butyl-4′-acetoxyphenyl)toluene with 9 via the Heck reaction.
Palladium acetate (215 mg, 0.958 mmol), tri-o-tolylphosphine
(583 mg, 1.92 mmol), and triethylamine (4.86 g, 47.9 mmol)
were added to a 0.5 M DMF (19.2 mL) solution of the 2-bromo-
4-(3′,5′-di-tert-butyl-4′-acetoxyphenyl)toluene (2.0 g, 4.80 mmol)
and 9 (1.7 g, 4.84 mmol) and stirred for 12 h at 90 °C: yield
60%; mp 127-128 °C; IR (KBr pellet, cm-1) 1765 (νCdO), 962
1
(δtransHCdCH); H NMR (CDCl3, 500 MHz; ppm) δ 1.41 (s, 36H,
tert-butyl), 2.38 (s, 6H, -O-CO-CH3), 2.84 (s, 3H, -CH3),
7.07-7.76 (m, 13H, Ar, CHdCH); 13C NMR (CDCl3, ppm) δ
19.66, 22.73, 31.54, 35.60, 124.60, 125.26, 125.44, 126.66,
126.79, 126.99, 127.58, 130.05, 130.76, 134.72, 136.50, 136.81,
137.81, 138.42, 139.93, 140.92, 142.66, 142.77, 147.46, 147.65,
171.20; MS (m/z) 686 (M+), calcd for M ) 686.4. Anal. Calcd
for C47H58O4: C; 82.17; H, 8.51. Found: C, 82.22; H, 8.52.
4-(3′,5′-Di-ter t-bu tyl-4′-a cetoxyp h en yl)styr en e (9).
A
3,5-di-tert-butyl-4-acetoxyphenyl group was introduced to p-
bromotoluene via the Grignard coupling reaction with (3,5-
di-tert-butyl-4-trimethylsiloxyphenyl)magnesium bromide us-
ing [1,3-bis(diphenylphosphino)propane]nickel(II) as a catalyst.
N-Bromosuccinimide (475 mg, 2.67 mmol) and AIBN were

High-Spin Polyphenoxyls
J . Org. Chem., Vol. 63, No. 21, 1998 7405
Sch em e 3
Sch em e 4
suspended in the CCl4 solution (25 mL) of 2-methyl-5,4′-bis-
(3,5-di-tert-butyl-4′-acetoxyphenyl)stilbene (1.83 g, 2.67 mmol)
and refluxed until succinimide floated on the solution. The
mixture was cooled to room temperature and filtered off. After
the filtrate was evaporated, benzene (25 mL) and triph-
enylphosphine (0.70 g, 2.67 mmol) were added, and the
solution was stirred at 50 °C for 6 h. The solution was poured
into diethyl ether to give the phosphonium salt (1.68 g): yield
61%.
δ 1.41 (s, 36H, tert-butyl), 2.37 (s, 6H, -O-CO-CH3), 5.39 (d,
1H, 10 Hz, -CHdCH2), 5.74 (d, 1H, 16 Hz, -CHdCH2), 7.13
(dd, 1H, 10 Hz, 16 Hz, -CHdCH2), 7.41-7.73 (m, 13H, Ar,
CHdCH); 13C NMR (CDCl3, ppm) δ 14.11, 22.65, 31.50, 35.57,
116.52, 125.22, 125.37, 125.44, 126.58, 126.78, 126.94, 126.99,
127.58, 131.10, 134.63, 135.24, 135.98, 136.31, 137.76, 138.01,
140.98, 141.36, 142.55, 142,73, 147.63, 147.66, 171.11; MS (m/
z) 698 (M+), calcd for M ) 698.4. Anal. Calcd for C48H58O4:
C; 82.48; H, 8.36. Found: C, 82.45; H, 8.38.
The phosphonium salt (1.5 g, 1.46 mmol) was suspended in
25% formaldehyde (15 mL), and 5 N NaOH (3 mL) was added
dropwise. The mixture was stirred for 1 h and extracted with
ether and then evaporated. The crude product was purified
by silica gel-column separation with hexane/CHCl3 eluent to
1,3,5-Tr is[4′-(3′′,5′′-d i-t er t -b u t yl-4′′-a ce t oxyp h e n yl)
styr yl] ben zen e (11′′). 1,3,5-Tris[4′-(3′′,5′′-di-tert-butyl-4′′-
acetoxyphenyl)styryl]benzene (11′′) was prepared via the same
Heck reaction. Palladium acetate (213 mg, 0.950 mmol), tri-
o-tolylphosphine (579 mg, 1.90 mmol), and trithylamine (4.81
g, 47.6 mmol) were added to a 0.5 M DMF (19.0 mL) solution
of 9 (2.5 g, 7.13 mmol) and 5 (1.01 g, 2.23 mmol) (9/5 ) 3.2):
yield 10: yield 60%; mp 111-112 °C; IR (KBr pellet, cm-1
)
1765 (νCdO), 962 (δtransHCdCH); 1H NMR (CDCl3, 500 MHz; ppm)

7406 J . Org. Chem., Vol. 63, No. 21, 1998
Nishide et al.
this solution was added n-butyllithium (14.3 mL of a 1.6 M
hexane solution, 22.9 mmol), the mixture was stirred for 1 h
at -78 °C, and then N,N-dimethylacetamide (2.19 g, 25.1
mmol) was added dropwise. The solution was allowed to warm
to ambient temperature overnight. The reaction was quenched
with dilute HCl (10%, 145 mL) and then extracted with CHCl3.
After evaporation, the orange crude product was purified by
recrystallization from ethanol to give 3,5-diiodoacetophenone
as a white crystal: yield 44%; mp ) 124-125 °C; IR (KBr
Ch a r t 3
1
pellet, cm-1) 1685 (νCdO); H NMR (CDCl3, 500 MHz; ppm) δ
2.55 (s, 3H, CH3), 8.21 (d, 2H, Ph), 8.23 (t, 1H, Ph); 13C NMR
(CDCl3, ppm) δ 26.5, 95.0, 136.5, 139.9, 149.3, 195.1; MS (m/
z) 372 (M+), calcd for M ) 371.9.
The solid mixture of 3,5-diiodoacetophenone (1.1 g, 2.96
mmol), concentrated H2SO4 (53.2 mg, 0.543 mmol), and K2S2O7
(0.96 g, 3.84 mmol) was heated to 180 °C for 12 h. The
brownish crude was purified by recrystallization from CHCl3
to give 13 as a white needle crystal: yield 32%; mp 427-429
°C; 1H NMR (CDCl3, 500 MHz; ppm) δ 7.58 (bs, 3H, Ph), 7.92
(bs, 6H, Ph), 8.22 (bs, 3H, Ph); 13C NMR (CDCl3, ppm) δ 98.8,
123.4, 129.2, 140.3, 145.6, 149.8; MS (m/z) 1062 (M+), calcd
for M ) 1061.7.
Ch a r t 4
1,3,5-Tr is[3′,5′-d i-p oly(4-(3′,5′-d i-ter t-b u t yl-4′-a cet ox-
yp h en yl)-1,2-p h en ylen evin ylen e)]ben zen e (14). Palla-
dium acetate (132 mg, 0.424 mmol), tri-o-tolylphosphine (358
mg, 0.848 mmol), 1,3,5-tris(3′,5′-diiodophenyl)benzene (52.3
mg, 48.5 µmol), and triethylamine (2.98 g, 21.2 mmol) were
added to a DMF solution (11.7 mL) of the styrene monomer 4
(2.5 g, 5.83 mmol), and the mixture was warmed at 45 °C for
6 h. The mixture was then heated to 90 °C for 18 h. The
mixture was separated using a polystyrene-gel column with
CHCl3 eluent and was purified by reprecipitation from CHCl3
in methanol to yield the polymer as a yellow powder: yield
62%; IR (KBr pellet, cm-1) 1765 (νCdO), 961 (δtransHCdCH); 1H
NMR (CDCl3, 500 MHz; ppm) δ 1.36 (s, 108H, tert-butyl), 2.34
yield 63%; IR (KBr pellet, cm-1) 1765 (νCdO), 960 (δtransHCdCH);
1H NMR (CDCl3, 500 MHz; ppm) δ 1.42 (s, 54H, tert-butyl),
2.38 (s, 9H, -O-CO-CH3), 7.22-7.74 (m, 27H, Ar, CHdCH);
13C NMR (CDCl3, ppm) δ 22.68, 31.50, 35.58, 125.21, 126.98,
127.60, 128.30, 129.09, 136.05, 137.74, 138.33, 140.99, 142.10,
142.73, 147.64, 171.12; FAB-MS (m/z) 1122.8 (M+), calcd for
M ) 1122.7. Anal. Calcd for C78H90O6: C; 83.38; H, 8.07.
Found: C, 83.40; H, 8.10.
11′′ (0.737 g, 0.66 mmol) was dissolved in a small amount
of THF. To its suspension in DMSO (71.5 mL) was added 2.5
N KOH (3.6 mL), and the solution was stirred at 40-50 °C
for 12 h, cooled to room temperature, and neutralized with 1
N HCl. The organic product was extracted with CHCl3 and
was evaporated to give 1,3,5-tris[4′-(3′′,5′′-di-tert-butyl-4′′-
hydroxyphenyl)styryl]benzene (11′): yield 73%; IR (KBr pellet,
cm-1) 3636 (νO-H), 960 (δtransHCdCH); 1H NMR (CDCl3, 500 MHz;
ppm) δ 1.45 (s, 54H, tert-butyl), 5.26 (s, 3H, OH), 7.19-7.76
(m, 27H, Ar, CHdCH); 13C NMR (CDCl3, ppm) δ 31.53, 34.57,
123.84, 126.41, 127.20, 127.98, 129.09, 132.13, 135.48, 136.33,
138.37, 140.80, 141.74, 153.92; FAB-MS (m/z) 996.2 (M+), calcd
for M ) 996.6. Anal. Calcd for C72H84O3: C; 86.70; H, 8.49.
Found: C, 86.66; H, 8.47.
(s, 18H, -O-CO-CH3), 7.13-7.88 (m, 54H, Ar, CHdCH); 13
C
NMR (CDCl3, ppm) δ 22.68 (CH3), 31.48, 35.53 (t-Bu), 124.53,
125.16, 125.32, 125.38, 126.57, 126.76, 126.97, 128.31, 128.61,
128.81, 130.32, 131.50, 134.57, 136.56, 137.88, 141.29, 142.69,
147.61 (aromatic), 171.07 (Ac). Anal. Calcd for (C24nH28n
-
Br3O2n)C24H12 (n ) 22): C, 78.52; H, 7.44; Br, 5.69. Found:
C, 78.50; H, 7.43; Br, 5.69; I, <0.01.
1,3,5-Tr is[3′,5′-d i-p oly(4-(3′,5′-d i-ter t-b u t yl-4′-h yd r ox-
yp h en yl)-1,2-p h en ylen evin ylen e)]ben zen e (15). 14 was
deprotected in an alkaline solution to yield the hydroxy
precursor 15: IR (KBr pellet, cm-1) 3640 (νO-H), 961 (δtransHCd
CH); 1H NMR (CDCl3, 500 MHz; ppm) δ 1.43 (s, 108H tert-
butyl), 5.24 (s, 6H, OH), 7.28-7.82 (m, 54H, Ar, CHdCH); 13
C
1,3,5-T r i s [2′-s t y r y l-{4′,5′′-b i s (3,5-d i -t er t -b u t y l-4-
a cet oxyp h en yl)st ilb en e}]b en zen e (12′′). 1,3,5-Tris[2′-
styryl-{4′,5′′-bis(3,5-di-tert-butyl-4-acetoxyphenyl)stilbene}]-
benzene was prepared in the same manner via the Heck
reaction; 10 (6.3 equiv) and 5 (1 equiv): yield 63%; IR (KBr
pellet, cm-1) 1765 (νCdO), 962 (δtransHCdCH); 1H NMR (CDCl3,
500 MHz; ppm) δ 1.32 (s, 108H, tert-butyl), 2.38 (s, 18H, -O-
CO-CH3), 7.22-7.82 (m, 48H, Ar, CHdCH); 13C NMR (CDCl3,
ppm) δ 22.54, 22.68, 31.43, 35.59, 124.52, 125.22, 125.37,
125.44, 126.58, 126.78, 126.94, 126.99, 127.58, 129.18, 130.51,
131.12, 134.63, 135.24, 135.98, 136.31, 137.76, 138.01, 140.98,
141.36, 142.55, 142,73, 147.43, 147.67, 171.03, 171.11; FAB-
MS (m/z) 2169 (M+), calcd for M ) 2169. Anal. Calcd for
NMR (CDCl3, ppm) δ 29.85, 33.96, 123.40, 123.60, 124.76,
126.32, 126.49, 126.75, 127.62, 128.08, 129.43, 131.70, 133.64,
134.71, 135.78, 136.12, 137.32, 141.44, 142.57, 153.17; mol wt
) 1.1 × 104. Anal. Calcd for (C22nH26nBr6On)C24H12 (n ) 34):
C, 82.83; H, 8.01; Br, 4.29. Found: C, 82.80; H, 8.04; Br, 4.29;
I, <0.01.
1,3,5-Tr is(3′,5′-d ibr om op h en yl)ben zen e (17). 3,5-Dibro-
moacetophenone was prepared in the same method of 13 using
1,3,5-triiodobenzene, to give a white crystal: yield 64%; mp
61-62 °C; IR (KBr pellet, cm-1) 1693 (νCdO); 1H NMR (CDCl3,
500 MHz; ppm) δ 2.59 (s, 3H, CH3), 7.85 (t, 1H, Ar), 8.00 (d,
2H, Ar); 13C NMR (CDCl3, ppm) δ 26.6, 123.5, 130.1, 138.2,
139.6, 195.2; MS (m/z) 276 (M+), 278 (M+ + 2), 280 (M+ + 4),
calcd for M ) 277.9.
C
150H174O12: C; 83.06; H, 8.09. Found: C, 83.04; H, 8.07.
12′′ was deprotected in an alkaline solution to yield 1,3,5-
tris[2′-styryl-{4′,5′′-bis(3,5-di-tert-butyl-4-hydroxyphenyl)-
stilbene}]benzene (12′): yield 68%; IR (KBr pellet, cm-1) 3640
(νO-H), 961 (δtransHCdCH); 1H NMR (CDCl3, 500 MHz; ppm) δ
1.47 (s, 108H, tert-butyl), 5.27 (s, 6H, OH), 7.08-7.86 (m, 48H,
Ar, CHdCH); 13C NMR (CDCl3, ppm) δ 30.55, 34.46, 123.84,
124.03, 124.13, 124.60, 125.77, 126.44, 126.81, 127.20, 127.98,
129.09, 130.38, 131.11, 132.13, 134.45, 135.36, 135.48, 136.17,
136.33, 136.45, 138.37, 140.80, 141.74, 153.34, 153.67; FAB-
MS (m/z) 1913 (M+), calcd for M ) 1913. Anal. Calcd for
The solid mixture of 3,5-dibromoacetophenone (3.9 g, 14.9
mmol), concentrated H2SO4 (252 mg, 2.57 mmol), and K2S2O7
(4.55 g, 18.2 mmol) was heated to give an off-white solid: yield
1
36; mp 314-315 °C; H NMR (CDCl3, 500 MHz; ppm) δ 7.65
(bs, 3H, Ar), 7.72 (bs, 9H, Ar); 13C NMR (CDCl3, ppm) δ 123.5,
125.9, 129.2, 133.4, 140.3, 143.62.
1 ,3 ,5 -T r i s [3 ′,5 ′-d i -{4 ′′-(3 ′′′,5 ′′′-d i -t e r t -b u t y l -4 ′′′-
a cetoxyp h en yl)styr yl}p h en yl]ben zen e (18′′). 18′′ was
prepared via the Heck reaction; 9 (1.42 g, 4.04 mmol) and 17
(0.5 g, 0.64 mmol) were dissolved in a DMF solution (18.7 mL)
of palladium acetate (4.74 g, 46.8 mmol), tri-o-tolylphosphine
(0.1050 g, 93.5 mmol), and triethylamine (0.2849 g, 46.8 mmol),
and the mixture was warmed at 90 °C for 18 h: yield 61%; IR
C
138H162O6: C; 86.47; H, 8.52. Found: C, 86.43; H, 8.53.
1,3,5-Tr is(3′,5′-d iiod op h en yl)ben zen e (13). 1,3,5-Tri-
iodobenzene (10.4 g, 22.9 mmol) was dissolved in a dry diethyl
ether (450 mL), and the solution was cooled at -78 °C. To

High-Spin Polyphenoxyls
J . Org. Chem., Vol. 63, No. 21, 1998 7407
(KBr pellet, cm-1) 1765 (νCdO), 962 (δtransHCdCH); 1H NMR
(CDCl3, 500 MHz; ppm) δ 1.40 (s, 108H, tert-butyl), 2.36
(s, 18H, -O-CO-CH3), 7.24-8.01 (m, 60H, Ar, CHdCH);
13C NMR (CDCl3, ppm); δ 22.68, 31.50, 35.58, 124.02,
125.03, 125.21, 126.98, 127.60, 128.30, 129.22, 136.03,
137.71, 138.53, 140.99, 142.18, 142.47, 142.66, 171.12; FAB-
MS (m/z) 2392 (found), calcd for M ) 2395. Anal. Calcd for
(C24H29O2)6C24H12: C, 84.17; H, 7.82; Br, 0. Found: C, 83.72;
H, 7.76; Br, <0.2.
turned deeply green after 10-20 min, which was ascribed to
the radical formation. The organic layer was dried over
anhydrous sodium sulfate.
ESR a n d SQUID Mea su r em en ts. ESR spectra were
taken using a J EOL J ES-TE200 ESR spectrometer with 100
kHz field modulation. Spin concentration of each sample was
determined both by careful integration of the ESR signal
standardized with that of TEMPO (2,2,6,6-tetramethyl-1-
piperidinyloxy) solution and by analyzing the saturated mag-
netization at the SQUID measurement.
The 2Me-THF or toluene solutions of the radicals were
immediately transferred to a diamagnetic capsule after the
oxidation. Magnetization and static magnetic susceptibility
were measured with a Quantum Design MPMS-7 SQUID
magnetometer. The magnetization was measured from 0.1 to
7 T at 1.8, 2.0, 2.5, 3, and 5 K. The static magnetic
susceptibility was measured from 2 to 100 K at a field of 0.5
T.
18′′ was deprotected in an alkaline solution to yield 1,3,5-
tris[3′,5′-di-{4′′-(3′′′,5′′′-di-tert-butyl-4′′′-hydroxyphenyl)styryl}-
1
phenyl]benzene (18′): yield 85%; H NMR (CDCl3, 500 MHz;
ppm) δ 1.50 (s, 108H, tert-butyl), 5.27 (s, 6H, OH), 7.20-8.10
(m, 60H, Ar, CHdCH); 13C NMR (CDCl3, ppm) δ 30.36, 34.51,
123.85, 124.88, 127.00, 127.22, 127.86, 129.36, 131.98, 135.34,
136.18, 136.28, 138.61, 141.67, 142.13, 142.52, 153.66; FAB-
MS (m/z) 2142 (found), calcd for M ) 2143. Anal. Calcd for
(C24H27O)6C24H12: C, 87.35; H, 8.18; Br, 0. Found: C, 86.92;
H, 8.13; Br, <0.2.
Ack n ow led gm en t. This work was partially sup-
ported by Grants-in-Aid for Scientific Research (Nos.
277/08246101 and 09305060) from the Ministry of
Education, Science and Culture, J apan, and by the
NEDO Project on Technology for Novel High-Functional
Materials.
Oxid a tion . A small excess of (n-C4H9) 4NOH was added to
a
2Me-THF or toluene solution (50 mL) of the hydroxy
precursors (0.025 unit mmol) under a nitrogen atmosphere in
a glovebox (for the ESR measurement; 2 mL and 0.06 unit
mmol, respectively, for SQUID). Then, the solution was
vigorously stirred with 10 mL of aqueous K3Fe(CN)6 (2.5 mmol;
10 equiv to the phenolate) at room temperature (1 mL and
0.6 mmol, respectively, for SQUID). The solution rapidly
J O981090H