Synthesis and through-bond spin interaction of stable 1,3-phenylene linked poly(phenothiazine cation radical)

Article abstract of DOI:10.1039/b716919a

A 1,3-phenylene linked poly(phenothiazine cation radical) was synthesized and its through-bond spin interaction was investigated. Monomer and dimer models were also synthesized to investigate the behaviour of spins in poly(phenothiazine cation radical). X-Ray crystallographic analysis of the monomer model showed that it has a near-planar structure, which is favourable for spin interaction through π-conjugation. MO calculation of the dimer model showed its exchange integral J (+31.4 K) is larger by about two times than that of diaminoxyl (+14.5 K) which is a dimer model of a polyradical studied previously. The spin state of poly(phenothiazine cation radical) was S = 2/2-3/2 in the ground state, indicating that, taking into account the average degree of polymerization (5-6) and the spin concentration (0.77 spins per repeating unit), 2-3 spins out of 4-5 spins per molecule were ferromagnetically aligned. The Royal Society of Chemistry.

Full text of DOI:10.1039/b716919a

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PAPER
www.rsc.org/materials | Journal of Materials Chemistry
Synthesis and through-bond spin interaction of stable 1,3-phenylene
linked poly(phenothiazine cation radical)†
*
Hiroyuki Oka
Received 1st November 2007, Accepted 6th February 2008
First published as an Advance Article on the web 7th March 2008
DOI: 10.1039/b716919a
A 1,3-phenylene linked poly(phenothiazine cation radical) was synthesized and its through-bond spin
interaction was investigated. Monomer and dimer models were also synthesized to investigate the
behaviour of spins in poly(phenothiazine cation radical). X-Ray crystallographic analysis of the
monomer model showed that it has a near-planar structure, which is favourable for spin interaction
through p-conjugation. MO calculation of the dimer model showed its exchange integral J (+31.4 K) is
larger by about two times than that of diaminoxyl (+14.5 K) which is a dimer model of a polyradical
studied previously. The spin state of poly(phenothiazine cation radical) was S ¼ 2/2–3/2 in the ground
state, indicating that, taking into account the average degree of polymerization (5–6) and the spin
concentration (0.77 spins per repeating unit), 2–3 spins out of 4–5 spins per molecule were
ferromagnetically aligned.
and MO calculations of these phenothiazine cation radicals
Introduction
were carried out and the results were compared with those of
aminoxyls 1p, 1m and 1d studied previously. The details are
reported.
Organic high spin molecules have been important units for
molecular magnetism.1–3 In the early stages of this research
field, it was demanded that a large number of spins are
ferromagnetically aligned regardless of stability of polyradicals
and 10–103 order spins could successfully be aligned in polycar-
benes and poly(triarylmethine radical)s.4–6 In the next stage,
from a point of view of use as practical materials, the stability
that can be treated in the atmosphere was demanded and
a wide variety of stable polyradicals have been studied.7–14
As spin sources of stable polyradicals, aminoxyls,7–10
phenoxyls11,12 and triarylamine cation radicals13,14 have often
been used because of convenience in synthetic strategy.
By the way, phenothiazine cation radical is a well-known
stable radical,15 but has not been used in this research field,
although phenothiazine cation radical dimers and trimers
were studied.16 Phenothiazine is a convenient molecule in
synthetic strategy, therefore, in this study, phenothiazine cation
radical was used in polyradicals. Previously, 1,3-phenylene
linked polyaminoxyl 1p, which is in the S ¼ 3/2 spin state,
was synthesized.10d Because 9,10-dihydroacridin-10-yloxyl,
which is a spin source of 1p, is similar to phenothiazine in
molecular structure, the performance of phenothiazine cation
radical as a spin source was investigated by substituting it
for 9,10-dihydroacridin-10-yloxyl, that is, poly(phenothiazine
cation radical) 2p, studied here. Also, monomer and dimer
models 2m and 2d were synthesized to investigate the behav-
iour of spins in 2p. ESR and magnetization measurements
Department of Advanced Materials, Institute of Technology and Science,
The University of Tokushima, 2-1 Minamijosanjima-cho, Tokushima
770-8506, Japan. E-mail: okah@opt.tokushima-u.ac.jp; Fax: +81 88 656
9435; Tel: +81 88 656 9424
† CCDC reference number 662325. For crystallographic data in CIF or
other electronic format see DOI: 10.1039/b716919a
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synthesized (Scheme 1). But the ESR spectrum of 2m-d10
[Fig. 1(b), upper] was almost same as that of 2m, indicating
that no isotope effect for ESR signal shapes appears. In the
case of N-alkylated phenothiazine cation radicals, the hyperfine
coupling (hfc) constant due to hydrogen nuclei at a-methylene is
large (ca. 0.36 mT).17 Therefore, other deuterated cation radicals
2m-d2 and 2m-d12 were also synthesized (Scheme 1). Both of their
ESR signal shapes were a simple triple line [Fig. 1(c)] and
different from those of 2m and 2m-d10, but there is no difference
between them. As a result, the isotope effect on the end two
phenyl groups could not be observed among these four cation
radicals. The hfc constants due to hydrogen nuclei on only the
phenothiazine moiety were estimated by computer-simulating
the spectrum of 2m-d10. From the spectra of 2m-d2 and 2m-d12,
the aN value of 0.730 mT could be estimated. With this aN
value, the spectrum of 2m-d10 was computer-simulated and the
following hfc constants were estimated: aH ¼ 0.108 (2H), 0.079
(2H), 0.036 (2H) and 0.362 mT (2H). The simulated spectrum
reproduced with these hfc constants [Fig. 1(b), lower] was in
excellent agreement with the spectrum of 2m-d10.
Results and discussion
Synthesis and ESR spectra of monomer models
Monomer model 2m was synthesized according to Scheme 1. 3,7-
Dibromophenothiazine (3) was alkylated with 1-bromooctane in
the presence of bases and a phase transfer catalyst and 3,7-
dibromo-10-n-octylphenothiazine (4) was obtained in 83% yield.
Suzuki–Miyaura coupling of 4 with phenylboronic acid gave 5 in
48% yield. The reaction of 5 with antimony(V) chloride gave 2m.
The recrystallization as final purification gave pure 2m in 44%
yield as dark green plates. Its elemental analysis showed that
an anion part was SbCl6, not SbCl5. The origin of another
chlorine atom would be excess antimony(V) chloride. The spin
concentration was measured by ESR to be 0.98 spins per
molecule.
The ESR spectrum of 2m was measured in dichloromethane at
room temperature [Fig. 1(a)]. The spectrum was observed at
g ¼ 2.0055, which is typical for phenothiazine cation radicals.17
The signal shape was not a triple line as often observed in
N-centered radicals or cation radicals. To confirm the delocaliza-
tion of the spin to the end of two phenyl groups which corre-
spond to 1,3-phenylene spin couplers in polymer 2p, cation
radical 2m-d10, which is deuterated at end phenyl groups, was
X-Ray crystallographic analysis of the monomer model and MO
calculations
Because single crystals of 2m could be obtained by recrystalliza-
tion, X-ray crystallographic analysis was carried out (Fig. 2).18
The phenothiazine moiety was quite planar, which is similar to
other phenothiazine cation radicals.16c,19 There were two
independent molecules in the crystals [Fig. 2(a)]. These mutually
Scheme 1 Synthetic route to monomer models.
Fig. 1 ESR spectra of (a) 2m, (b) 2m-d10 and (c) 2m-d12 in dichlorome-
thane at room temperature. The lower spectrum in Fig. 1(b) is the
simulated spectrum.
Fig. 2 ORTEP drawing of 2m at 50% probability. (a) Crystal packing.
SbCl6 anions and n-octyl groups are omitted for clarity. (b) One of two
independent molecules.
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face upside-down at the phenothiazine plane and the distance
˚
between phenothiazine planes is ca. 3.2 A [only two pairs are
depicted in Fig. 2(a)], indicating that strong p–p intermolecular
interaction acts between these. Dihedral angles between
phenothiazine and the two phenyl end groups are ꢀ12.0ꢁ
(C5–C4–C13–C18) and 24.2ꢁ (C11–C10–C19–C24) in one of
two independent molecules shown in Fig. 2(b) and ꢀ22.5 and
3.9ꢁ in another molecule. All four dihedral angles are smaller
than dihedral angles of phenyl–phenyl compounds such as
biphenyl, indicating that 2m has a near-planar structure. Ortho
hydrogens to a phenothiazine–phenyl bond are ordinarily
sterically hindered. Actually, X-ray crystallographic data of
3-phenyl-10-methylphenothiazine showed that the correspond-
ing dihedral angle is 36.96ꢁ.20 Neutral precursor 5 would also
have comparably large dihedral angles, but, in 2m that is
a one-electron oxidized molecule of 5, resonance stabilization
would strongly function to overcome steric hindrance of ortho
hydrogens.
Fig. 3 Calculated spin density distribution of 2m.
Synthesis, ESR spectra and magnetization measurements of the
dimer model
In this study, 1,3-phenylene is used as a spin coupler to align
spins ferromagnetically through bonds. For phenothiazine
cation radicals, 1,3-phenylene cannot always give ferromagnetic
spin interaction in the ground state. The ESR study of 10,100-
(1,3- and 1,4-phenylene)diphenothiazines in sulfuric acid showed
that the 1,4-phenylene linked isomer is in the triplet ground state,
while the 1,3-phenylene linked isomer is in the singlet ground
state.16a Here, dimer model 2d was synthesized and its spin state
was investigated.
Based on the structure shown in Fig. 2(b), MO calculation was
performed to estimate the spin density distribution in 2m. The
reliability of the MO calculation was confirmed by comparing
the hfc constants calculated here with those estimated from the
ESR spectra above. Calculations were performed with the
UB3LYP/6-31G(d) model. The results are listed in Table 1.
The calculated hfc constants are in good agreement with the
The synthesis was carried out according to Scheme 2.
Suzuki–Miyaura coupling of two equimolar amounts of
3-bromo-10-n-octylphenothaizine (6) with 1,3-phenylenebis
(trimethylene boronate) (7) gave precursor 8 in 34% yield. The
reaction of 8 with antimony(V) chloride gave 2d. As a final
purification, the reprecipitation was carried out to give pure 2d
in 19% yield. The spin concentration was measured by ESR to
be 1.90 spins per molecule, that is, the spin generation percentage
was 95%.
0
observed ones, except for H3,3 and H7 nuclei. The spin density
distribution calculated simultaneously is shown in Fig. 3. Spin
densities on end phenyl groups are |0.012ꢀ0.040|, indicating
the delocalization of the spin. These spin densities are higher
than those in aminoxyl 1m (|0.011ꢀ0.025|), therefore, through-
bond spin interaction would be more effective in polymer 2p
than in 1p.
Table 1 Observed and calculated hfc constants for 2ma
The ESR spectra of 2d were measured in dichloromethane
[Fig. 4(a)]. The spectra were observed at g ¼ 2.0051 as a broad
single line. To observe intramolecular spin interaction, the
spectrum was also measured in a poly(methyl methacrylate)
(PMMA) matrix [Fig. 4(b)]. The signals due to the triplet species
could not be confirmed in the DMS ¼ ꢂ1 transition, but
the DMS ¼ ꢂ2 transition was observed at 162 mT at 77 K. On
the other hand, the external magnetic field dependence of the
magnetization of 2d was measured in PMMA matrix by
a SQUID magnetometer (Fig. 5). The experimental data shows
that 2d is in the S ¼ 2/2 spin state in the ground state, although
only the data at 2 K deviate downward from the S ¼ 2/2
Nucleus
N
Obsdb
Calcdc
0.730
0.079
0.108
0.036
n. e.d
0.667
ꢀ0.080 (1), ꢀ0.079 (10)
ꢀ0.102 (2), ꢀ0.093 (20)
0.083 (3), 0.083 (30)
ꢀ0.064 (4), ꢀ0.073 (4),
ꢀ0.059 (40), ꢀ0.062 (40)
0.024 (5), 0.030 (5), 0.023
(50), 0.026 (50)
0
H1,1
H2,2
0
0
H3,3
H4,4
0
n. e.d
0
H5,5
H6,6
H7
n. e.d
0.362
ꢀ0.089 (6), ꢀ0.076 (60)
0
0.245, 0.280
a
b
Given in mT. Estimated by computer-simulating the observed ESR
c
spectra. MO calculation. The numbers in parentheses denote the
subscript number of a hydrogen atom. Phenyl rings carrying H4–H6 and
0
H4 –H6 correspond to phenyl rings C13–C18 and C19–C24 in Fig. 2(b),
0
d
respectively. Not estimated.
Scheme 2 Synthetic route of the dimer model.
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Fig. 4 ESR spectra of 2d (a) in dichloromethane and (b) in PMMA
matrix at room temperature. The DMS ¼ ꢂ2 transition was observed
at 162 mT at 77 K.
Fig. 6 Geometry for MO calculation. (a) 1d. :C5–C4–C13–C18 ¼
27.2ꢁ, :C50–C40–C15–C16 ¼ 37.8ꢁ. (b) 2d. :C5–C4–C13–C18 ¼
12.0ꢁ, :C50–C40–C15–C16 ¼ 24.2ꢁ.
Synthesis and magnetization measurement of poly(phenothiazine
cation radical)s
Fig. 5 External magnetic field dependence of the magnetization of 2d in
PMMA matrix (6.3 wt% content). The points are the experimental data
at 2, 4 and 6 K. The lines are the theoretical lines for S ¼ 1/2, 2/2, 3/2 and
4/2 given by the Brillouin function.
Polymers 2p were synthesized according to Scheme 3. The
precursor polymer 9a was prepared by Suzuki–Miyaura coupling
of dibromo monomer 4 with diboron monomer 7. The yield was
88%. Polymer 9a was insoluble to any organic solvents in spite of
attaching n-octyl groups. The reaction of 9a with the antimo-
ny(V) chloride was carried out in inhomogeneous state to give
2p-a in 85% yield. Polymer 2p-a was also insoluble. This insolu-
bility could be due to strong intermolecular interaction between
phenothiazine moieties as shown in X-ray crystallographic
analysis of the monomer model 2m. Insolubility prevents the
measuring of through-bond spin interaction in dilute states
such as the polymer matrix. Therefore, in order to enhance
solubility of polymers, the di-n-octylmethoxymethyl group,
which has a radially expanding long alkyls, was introduced on
the 1,3-phenylene moiety, that is, precursor polymer 9b was
prepared.26 The preparation was carried out by Suzuki–Miyaura
coupling of dibromo monomer 12 with diboron monomer 14.
Monomer 12 was prepared from methyl 3,5-dibromobenzoate
(10). The reaction of two equimolar amounts of n-octylmagne-
sium bromide with 10 gave 11 in 69% yield and the following
methylation of the hydroxy group of 11 with dimethyl sulfate
in the presence of sodium hydroxide gave 12 in 24% yield.
Monomer 14 was prepared by an ordinary method of arylbor-
onic acid esters from 4. The total yield from 4 was 24%.
Suzuki–Miyaura coupling of 12 with 14 gave 9b in 95% yield.
Although 9b was deposited in the course of the coupling, it
was soluble in dichloromethane and THF, in dilute state. The
molecular weight of 9b was measured by size exclusion chroma-
tography (SEC) with a polystyrene standard. The number- and
weight-averaged molecular weights were 3590 and 5670,
respectively, therefore, the polydispersity was 1.58. Taking into
theoretical line, which would be due to intermolecular antiferro-
magnetic spin interaction.21 These results show that 1,3-phenyl-
ene gives ferromagnetic through-bond spin interaction in this
study.
The intramolecular exchange integral J for dimer model 2d
was calculated in MO calculation. The J value for 1d which is
a dimer model of polyradical 1p was also calculated and
compared with that for 2d. In these calculations, the energies
of the singlet and triplet states were calculated taking into
account the broken-symmetry (BS) problem for the lowest spin
states and spin projection was carried out with eqn (1) to
eliminate spin contamination effects in the BS lower spin states
contributed from the higher spin states.22,23
ES ꢀ ET
J ¼
(1)
\S2 .T ꢀ\S2 .S
The geometries of 1d and 2d were constructed based on the
X-ray crystallographic data of 1m and 2m, respectively
(Fig. 6).24 The calculated J value for 1d was +14.5 K.25 This value
is appropriate in taking into account that the average exchange
integral for 1p is J/k ¼ +8.6 K.10d The calculated value for 2d
was +31.4 K and larger by about two times than that for 1d.25
One of the factors affecting those differences is planarity. As
observed in X-ray crystallographic analysis above, 2m has
a near-planar structure. This is favourable for spin interaction
through p-conjugation.
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experimental data at 2, 4 and 6 K are between the theoretical
lines for S ¼ 2/2 and 3/2 given by the Brillouin function,
indicating that 2p-b is in the S ¼ 2/2–3/2 spin state. From the
average degree of polymerization of 5–6 and the spin concentra-
tion of 0.77 spins per repeating unit, there were ca. 4–5 spins per
molecule. In 2p-b, 2ꢀ3 spins out of 4ꢀ5 spins were ferromagneti-
cally aligned. Compared with the result that 3 spins out of 8 spins
per molecule were aligned in polymer 1p, more effective through-
bond spin interaction would occur in 2p-b than in 1p. To confirm
this in detail, further investigation should be carried out, for
example, influence of spin defects on through-bond spin interac-
tion. But this is not easy. If the molecular weight of 2p-b
increases, a higher spin state will be attained, but problems
such as insolubility of polymers have to be solved.
Conclusion
1,3-phenylene linked poly(phenothiazine cation radical) 2p-b was
synthesized and its through-bond spin interaction was investi-
gated. Precursor polymers were prepared by Suzuki–Miyaura
coupling of dibromo- with diboron monomers. To enhance the
solubility of the precursor polymer, the di-n-octylmethoxymethyl
group, which is a radially expanding long alkyl, had to be
introduced on the 1,3-phenylene moiety. Monomer and dimer
models 2m and 2d were also synthesized to investigate the
behaviour of spins in 2p. X-Ray crystallographic analysis of
2m showed that 2m has a near-planar structure, which is
favourable for spin interaction through p-conjugation. MO
calculation of dimer model 2d showed that the exchange integral
J of 2d (+31.4 K) is larger by about two times than that of 1d
(+14.5 K) which is a dimer model of a polyradical studied
previously. The spin state of 2p-b was S ¼ 2/2–3/2 in the ground
state, indicating that, taking into account the average degree of
polymerization (5–6) and the spin concentration (0.77 spins per
repeating unit), 2–3 spins out of 4–5 spins per molecule were
ferromagnetically aligned.
Scheme 3 Synthetic route to polymers.
account the molecular weight of the repeating unit, the average
degree of polymerization was 5–6. The reaction of 9b with
antimony(V) chloride gave 2p-b in 70% yield as a dark green
powder. Polymer 2p-b was soluble in dichloromethane,
therefore, the spin concentration could be estimated by ESR.
The value was 0.77 spins per repeating unit.
Experimental section
The spin state of 2p-b was investigated by measuring the
external magnetic field dependence of the magnetization in
a PMMA matrix with a SQUID magnetometer (Fig. 7). The
Measurements
1H-NMR spectra were measured with a JEOL JNM-EX400
spectrometer (400 MHz). Tetramethylsilane was used as an
internal standard for chemical shifts. IR spectra were measured
with a JASCO FT/IR-230 spectrometer. The melting point was
measured on a Yanagimoto micro-melting point apparatus.
SEC measurement was carried out with a TOSOH HLC-8020
chromatograph. THF was used as an eluant and the temperature
was kept at 40 ꢁC. X-Ray crystallographic analysis was
performed with
a Rigaku RAXIS-RAPID Imaging Plate
diffractometer. ESR spectra were measured with a JEOL JES-
RE1X spectrometer (X-band). Mn2+ was used as a standard
for g values. The spin concentration was estimated by a solution
ESR measurement in dichloromethane and 1,3,5-triphenylverda-
zyl was used as a standard stable radical. The magnetization was
measured with
a Quantum Design MPMS-7T SQUID
Fig. 7 External magnetic field dependence of the magnetization of 2p-b
in PMMA matrix (6.9 wt% content). The spin concentration is 0.77 spins
per repeating unit. The points are the experimental data at 2, 4 and 6 K.
The lines are the theoretical lines for S ¼ 1/2, 2/2, 3/2 and 4/2 given by the
Brillouin function.
magnetometer. The external magnetic field dependence of
the magnetization was measured in the region of 0–6 T at
a constant temperature. The magnetization of diamagnetic
compounds such as PMMA was previously measured and the
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contribution was corrected. All MO calculations were performed
with Gaussian 03.27
J 7.1, CH3), 1.19–1.43 (8H, m, CH2), 1.52 (2H, q, J 7.6, CH2),
1.86 (2H, q, J 7.1, CH2), 4.03 (2H, t, J 7.1, CH2), 7.12 (2H, d,
J 8.5, ArH), 7.45 (2H, d, J 2.2, ArH), 7.50 (2H, dd, J 8.5 and
2.2, ArH).
Materials
3,7-Dibromophenothiazine (4),28 1-bromo-1,1-dideuterooc-
tane,29 and methyl 3,5-dibromobenzoate (10)30 were prepared
according to the reported method. Pentadeuterophenylboronic
acid was prepared by a similar method to that used to prepare
3,7-Diphenyl-10-(n-1,1-dideuterooctyl)phenothiazine (5-d2).
The preparative method was similar for 5. 4-d2 was used instead
1
of 4. Yield: 54.3%. Viscous yellow oil. H-NMR (acetone-d6)
d 0.85 (3H, t, J 7.1, CH3), 1.18–1.40 (8H, m, CH2), 1.50 (2H,
q, J 7.5, CH2), 1.84 (2H, t, J 7.3, CH2), 7.11 (2H, d, J 8.5,
ArH), 7.32 (2H, tt, J 7.3 and 1.2, ArH), 7.35–7.45 (6H, m,
ArH), 7.50 (2H, dd, J 8.5 and 2.2, ArH), 7.61 (4H, dd, J 7.3
and 1.2, ArH).
phenylboronic
acid
from
bromopentadeuterobenzene.
3-Bromo-10-n-octylphenothiazine (6) was prepared by a similar
method to that used to prepare 3-bromo-10-n-hexylphenothia-
zine from 10-n-octylphenothiazine.31 The preparative method
of 1.3-phenylenebis(trimethylene boronate) (7) was previously
reported.32 Reagents except for these were purchased and used
without further purification.
3,7-Bis(pentadeuterophenyl)-10-(n-1,1-dideuterooctyl)pheno-
thiazine (5-d12). The preparative method was similar for 5.
Pentadeuterophenylboronic acid and 4-d2 were used instead of
phenylboronic acid and 4, respectively. Yield: 47.1%. Viscous
3,7-Dibromo-10-n-octylphenothiazine (4). To a solution of 3
(5.36 g, 15 mmol) and 1-bromooctane (7.53 g, 39 mmol) in
toluene (25 mL) were added potassium hydroxide (5.94 g, 90
mmol), potassium carbonate (3.32 g, 24 mmol), and tetra
(n-butyl)ammonium hydrogensulfate (0.509 g, 1.5 mmol) and
the mixture was heated at 80 ꢁC for 2 h. After solids were filtered
out, the filtrate was evaporated and the residue underwent
chromatography on silica with dichloromethane–hexane
(1 : 4) to give 4 in 83.3% yield (5.86 g, 12.5 mmol). Yellow
1
yellow oil. H-NMR (acetone-d6) d 0.85 (t, J ¼ 7.1 Hz, 3H),
1.18ꢀ1.40 (m, 8H), 1.50 (q, J ¼ 7.6 Hz, 2H), 1.84 (t, J ¼ 7.1
Hz, 2H), 7.11 (d, J ¼ 8.5 Hz, 2H), 7.44 (d, J ¼ 2.0 Hz, 2H),
7.50 (dd, J ¼ 8.5 and 2.2 Hz, 2H).
Monomer model 2m. To a solution of 5 (100 mg, 0.22 mmol) in
dichloromethane (2 mL) was added antimony(V) chloride (0.129
g, 0.43 mmol). The mixture was stirred for 20 min at room
temperature and poured into hexane (10 mL). The precipitate
was collected and recrystallized from dichloromethane–benzene
to give 2m in 43.5% yield (75 mg, 0.094 mmol). Mp. 144–145 ꢁC.
Anal. Calc. for C32H33Cl6NSSb: C, 48.15; H, 4.17; N, 1.75%.
Found: C, 48.21; H, 4.27; N, 1.64%.
oil. 1H-NMR (chloroform-d)
d
0.86 (3H, t,
J
7.1,
CH3), 1.14ꢀ1.51 (10 H, m, CH2), 1.74 (2H, q, J 7.3, CH2),
3.75 (2H, t, J 7.3, CH2), 6.68 (2H, d, J 8.5, ArH), 7.20–7.32
(4H, m, ArH).
3,7-Dibromo-10-n-(1,1-dideuterooctyl)phenothiazine (4-d2).
The preparative method was similar for 4. 1-Bromo-1,1-dideu-
Monomer model 2m-d10. The preparative method was similar
for 2m. Yield: 49.5%. Mp. 144ꢀ145 ꢁC. Anal. Calc. for
C32H23D10Cl6NSSb: C, 47.55; H, 4.12; N, 1.73%. Found: C,
47.42; H, 4.15; N, 1.72%.
terooctane was used instead of 1-bromooctane. Yield: 73.8%.
1
Yellow oil. H-NMR (chloroform-d) d 0.86 (3H, t, J 7.1, CH3),
1.14–1.49 (10 H, m, CH2), 1.74 (2H, t, J 7.1, CH2), 6.67 (2H,
d, J 8.5, ArH), 7.19–7.28 (4H, m, ArH).
Monomer model 2m-d2. The preparative method was similar
for 2m. Yield: 31.2%. Mp. 157–159 ꢁC. Anal. Calc. for
C32H31D2Cl6NSSb: C, 48.03; H, 4.16; N, 1.75%. Found: C,
47.92; H, 4.15; N, 1.76%.
3,7-Diphenyl-10-n-octylphenothiazine (5). To a solution of 4
(0.469 g, 1.0 mmol) and phenylboronic acid (0.366 g, 3.0
mmol) in THF (9 mL) were added a 2 M potassium carbonate
aqueous solution (3 mL), tetra(n-butyl)ammonium bromide
(1.29 g, 4.0 mmol) and tetrakis(triphenylphosphine)palladium
(69 mg, 0.06 mmol) and the mixture was refluxed for 7 h under
nitrogen. The organic layer was separated and dried with
anhydrous magnesium sulfate. After evaporation, the residue
underwent chromatography on silica with dichloromethane–
hexane (1 : 5) to give 5 in 48.3% yield (0.224 g, 0.483 mmol).
Monomer model 2m-d12. The preparative method was similar
for 2m. Yield: 42.9%. Mp. 154–155 ꢁC. Anal. Calc. for
C32H21D12Cl6NSSb: C, 47.44; H, 4.11; N, 1.73%. Found: C,
47.24; H, 4.08; N, 1.75%.
1,3-Phenylene-3,30-bis(10-n-octylphenothiazine) (8). To a solu-
tion of 6 (0.781 g, 2.0 mmol) and 7 (0.246 g, 1.0 mmol) in
THF (10 mL) were added 2 M potassium carbonate aqueous
solution (2 mL), tetra(n-butyl)ammonium bromide (0.870 g,
2.7 mmol) and tetrakis(triphenylphosphine)palladium (69 mg,
0.06 mmol) and the mixture was refluxed for 9 h under nitrogen.
The organic layer was separated and dried with anhydrous
magnesium sulfate. After evaporation, the residue underwent
chromatography on silica with dichloromethane–hexane (1 : 3)
to give 7 in 34.1% yield (0.238 g, 0.341 mmol). Viscous yellow
1
Viscous yellow oil. H-NMR (acetone-d6) d 0.85 (3H, t, J 7.1,
CH3), 1.21–1.41 (8H, m, CH2), 1.51 (2H, q, J 7.6, CH2), 1.86
(2H, q, J 7.1, CH2), 4.02 (2H, t, J 7.1, CH2), 7.12 (2H, d,
J 8.5, ArH), 7.32 (2H, tt, J 7.3 and 1.2, 2H), 7.42–7.47
(6H, m), 7.50 (2H, dd, J 8.5 and 2.2, ArH), 7.63 (4H, dd, J 7.3
and 1.2, ArH).
3,7-Bis(pentadeuterophenyl)-10-n-octylphenothiazine (5-d10).
The preparative method was similar for 5. Pentadeuterophenyl-
boronic acid was used instead of phenylboronic acid. Yield:
1
oil. H-NMR (chloroform-d) d 0.87 (6H, t, J 6.8, CH3), 1.05–
1
50.0%. Viscous yellow oil. H-NMR (acetone-d6) d 0.85 (3H, t,
1.51 (20H, m, CH2), 1.84 (4H, q, J 6.3, CH2), 3.87 (4H, t,
1932 | J. Mater. Chem., 2008, 18, 1927–1934
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1
J 7.1, CH2), 6.80–7.02 (6H, m, ArH), 7.08–7.22 (4H, m, ArH),
oil. IR (KBr): 2923 cmꢀ1 (CH2). H-NMR (acetone-d6) d 0.85
(3H, t, J 7.1, CH3), 1.14–1.38 (8H, m, CH2), 1.47 (2H, q, J 7.1,
CH2), 1.80 (2H, q, J 7.1, CH2), 4.00 (2H, t, J 7.1, CH2), 4.34
(8H, s, OCH2), 7.05 (2H, d, J 8.8, ArH), 7.46 (2H, d, J 1.2,
ArH), 7.58 (2H, dd, J 8.0 and 1.3, ArH).
7.36–7.52 (8H, m, ArH).
Dimer model 2d. To a solution of 8 (75 mg, 0.108 mmol) in
dichloromethane (3 mL) was added antimony(V) chloride
(0.097 g, 0.324 mmol). The mixture was stirred for 20 min at
room temperature and poured into hexane (20 mL). The precip-
itate was collected and preprecipitated from dichloromethane–
ether (1 : 5) to give 2d in 19.0% yield (28 mg, 0.0205 mmol).
Polymer 9a-b. To a solution of dibromo monomer (4 or 12)
(1.00 mmol) and diboron monomer (7 or 14) (1.00 mmol) in
THF (10 mL) were added a 2 M potassium carbonate aqueous
solution (2 mL), tetra-n-butylammonium bromide (0.870 g,
2.67 mmol) (for 9a) or Aliquat 336 (0.40 mmol, 0.163 g) (for
9b) and tetrakis(triphenylphosphine)palladium (69 mg, 0.06
mmol) and the mixture was refluxed for 24 h under nitrogen.
The organic layer was separated, washed with a 5% sodium
cyanide aqueous solution (3 mL) and brine and dried with
anhydrous magnesium sulfate. After evaporation, the residue
was reprecipitated from THF–methanol (7 mL–70 mL) to give
9a-b as light yellow powders.
ꢁ
Mp. 135–136 C. Anal. Calc. for C46H52Cl12N2S2Sb2: C, 40.45;
H, 3.84; N, 2.05%. Found: C, 40.66; H, 4.04; N, 2.06%.
9-(3,5-Dibromophenyl)-n-heptadecanol (11). To a solution of
10 (4.41 g, 15.0 mmol) in dry ether (15 mL) was added dropwise
n-octylmagnesium bromide prepared from magnesium (1.20 g,
49.5 mmol) and 1-bromooctane (8.69 g, 45 mmol) in dry ether
(45 mL) at 0 ꢁC and the mixture was stirred for 3 days at
room temperature. To the mixture was added saturated ammo-
nium chloride aqueous solution (30 mL) slowly at 0 ꢁC and
extracted with ether, washed with brine and dried with anhy-
drous magnesium sulfate. After evaporating, the residue under-
went chromatography on silica with dichloromethane–hexane
(2 : 3) to give 11 in 68.7% yield (5.06 g, 10.3 mmol). Colourless
oil. IR (KBr): 3473 cmꢀ1 (OH), 2925 cmꢀ1 (CH2 and CH3).
1H-NMR (chloroform-d) d 0.86 (6H, t, J 7.1, CH3), 1.14–1.36
(24H, m, CH2), 1.69–1.77 (4H, m, CH2), 7.45 (2H, d, J 1.7,
ArH), 7.52 (1H, t, J 1.7, ArH).
9a: Yield 87.7% (0.338 g). Anal. Found: C, 80.72; H, 7.12; N,
3.54%. Calcd for (C26H27NS)n: C, 80.99; H, 7.06; N, 3.63%.
9b: Yield 95.4% (0.624 g). 1H-NMR (dichloromethane-d2)
d 0.86 (9H, br s, CH3), 1.01–1.42 (34H, m, CH2), 1.86 (6H, br
s, CH2), 3.11 (3H, s, OCH3), 3.93 (2H, br s, CH2), 6.88–7.10
(2H, m, ArH), 7.26–7.85 (7H, m, ArH). Anal. Found: C,
80.65; H, 9.70; N, 2.21%. Calcd for (C44H63NOS)n: C, 80.80;
H, 9.71; N, 2.14%.
Polymer 2p-a. To a solution of 9a (0.050 g) in dichloromethane
(15 mL) was added antimony(V) chloride (0.117 g, 0.390 mmol).
The mixture was stirred for 30 min at room temperature, concen-
trated to ca. 5 mL and poured into ethyl acetate (25 mL) to give
2p-a in 85.4% yield (0.080 g). Anal. Found: C, 43.17; H, 3.93; N,
1.81%. Calcd for (C26H27Cl6NSSb)n: C, 43.37; H, 3.78; N, 1.95%.
9-(3,5-Dibromophenyl)-9-methoxy-n-heptadecane (12). To
a solution of 11 (3.15 g, 6.42 mmol) in toluene were added
dimethyl sulfate (1.61 g, 12.8 mmol), pulverized sodium
hydroxide (1.02 g, 25.6 mmol) and tetra-n-butylammonium
hydrogensulfate (0.218 g, 0.642 mmol), and the mixture was
refluxed for 2.5 h. After solid components were filtered out, the
filtrate was evaporated and the residue underwent chromatog-
raphy on silica with dichloromethane–hexane (1 : 2) to give 12
Polymer 2p-b. To a solution of 9b (0.100 g) in dichloromethane
(30 mL) was added antimony(V) chloride (0.115 g, 0.383 mmol).
The mixture was stirred for 20 min at room temperature, concen-
trated to ca. 3 mL and poured into ethyl acetate (45 mL) to give 2p
in 69.9% yield (0.106 g). Anal. Found: C, 53.22; H, 5.94; N, 1.49%.
Calcd for (C44H63Cl6NOSSb)n: C, 53.46; H, 6.42; N, 1.42%.
1
in 24.3% yield (0.789 g, 1.56 mmol). Colourless oil. H-NMR
(chloroform-d) d 0.87 (6H, t, J 7.3, CH3), 0.94–1.16 (4H, m,
CH2), 1.16–1.35 (20H, m, CH2), 1.60–1.72 (2H, m, CH2), 1.73–
1.85 (2H, m, CH2), 3.08 (3H, s, OCH3), 7.44 (2H, d, J 1.7,
ArH), 7.53 (1H, t, J 1.7, ArH).
Acknowledgements
Diboron monomer 14. To a solution of 4 (7.04 g, 15.0 mmol) in
anhydrous THF (35 mL) was added dropwise n-butyllithium
(1.6 M, 20.7 mL) at ꢀ78 ꢁC under nitrogen and the mixture
was stirred for 1.5 h at ꢀ78 ꢁC. To the resulting mixture was
added dropwise triisopropyl borate (11.3 g, 60.0 mmol) at
The author thanks Prof. Y. Miura and R. Tanaka (Osaka City
University) for X-ray crystallographic analysis. The author
also thanks Instrument Center, Institute for Molecular Science
for use of a SQUID magnetometer.
ꢁ
ꢁ
ꢀ78 C and the mixture was stirred for 1.5 h at ꢀ78 C and all
night at room temperature. A saturated ammonium chloride
aqueous solution (30 mL) was added slowly at 0 ꢁC and the
organic layer was separated, washed with brine and dried with
anhydrous magnesium sulfate. After evaporating and drying in
vacuo, 3,7-bis(dihydroxyboryl)-10-n-octylphenothaizine (13)
was obtained as a crude product. To a solution of the crude
product in THF (20 mL) was added ethylene glycol (5.52 g, 89
mmol) and the mixture was refluxed for 4 h. The THF layer
was separated and evaporated. The residue underwent chroma-
tography on silica with dichloromethane–ethyl acetate (1 : 1)
to give 14 in 24.1% yield (1.63 g, 3.61 mmol). Viscous yellow
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24 Although dihedral angle :C5–C4–C13–C18 was ꢀ12.0ꢁ in 2m
(Fig. 2(b)), :C5–C4–C13–C18 ¼ 12.0ꢁ was used in 2d, because two
dihedral angles in 1m were positive and, in the case of ꢀ12.0ꢁ,
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state are almost 0.
25 For 1d and 2d, the UB3LYP/6-31G and UB3LYP/6-31G(d) models
were used, respectively. 1d: ES¼ ꢀ1963.00529703 hartree, <S2 >
¼
S
1.0274, ET ¼ ꢀ1963.00534307 hartree and <S2 > T ¼ 2.0287. 2d: ES¼
ꢀ2689.03796769 hartree, <S2
>
¼ 1.0157, ET ¼ ꢀ2689.03806737
S
hartree and <S2 > ¼ 2.0175.
T
26 Before 9b, the n-octyl and t-butyl groups were used as the substituents
on the 1,3-phenylene moiety. But polymers carrying these
substituents were insoluble.
27 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery, Jr., T. Vreven,
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17 For example, (a) N. Helle, H. Kurreck, M. Bock and W. Kieslich,
Magn. Reson. Chem., 1985, 11, 965; (b) F. L. Ruperez, J. C. Conesa
and J. Soria, J. Chem. Soc., Perkin Trans. 2, 1986, 3, 391.
18 2m. Empirical formula: C32H33Cl6NSSb; formula weight: 798.10;
temperature ¼ 193(2) K; crystal system: monoclinic; space group:
p21/a; unit cell dimensions: a ¼ 13.7062(5), b ¼ 21.5592(8), c ¼
ꢁ
3
˚
˚
22.5411(8) A, a ¼ 90, b ¼ 94.493(2), g ¼ 90 ; V ¼ 6640.3(4) A ;
Z ¼ 8; m(Mo Ka) ¼ 1.401 mmꢀ1; reflections collected ¼ 50 420,
independent collections ¼ 14 820 (Rint ¼ 0.0296), GOF ¼ 1.170,
Final R indices [I > 2s(I)]: R1 ¼ 0.0526,,wR2 ¼ 0.1083; R indices
(all data): R1 ¼ 0.0590, wR2 ¼ 0.1113. CCDC reference number
662325.
19 For example, D. Sun, S. V. Rosokha and J. K. Kochi, J. Am. Chem.
Soc., 2004, 126, 1388.
20 C. S. Kra¨mer, K. Zeitler and T. J. J. Muller, Tetrahedron Lett., 2001,
42, 8619.
¨
1934 | J. Mater. Chem., 2008, 18, 1927–1934
This journal is ª The Royal Society of Chemistry 2008