New conjugated electroluminescent triphenylamine-containing polymers with side-chain pyridin-2-ylimidazo[1,5-a]pyridine groups for polymer light-emitting diodes

Full text of DOI:10.1134/S0012500813060050

ISSN 0012ꢀ5008, Doklady Chemistry, 2013, Vol. 450, Part 2, pp. 165–172. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © M.L. Keshtov, FangꢀChung Chen, E.I. Maltsev, D.V. Marochkin, V.S. Kochurov, A.R. Khokhlov, 2013, published in Doklady Akademii Nauk, 2013,
Vol. 450, No. 6, pp. 673–681.
CHEMISTRY
New Conjugated Electroluminescent TriphenylamineꢀContaining
Polymers with SideꢀChain Pyridinꢀ2ꢀylimidazo[1,5ꢀa]pyridine
Groups for Polymer LightꢀEmitting Diodes
M. L. Keshtova, FangꢀChung Chenb, E. I. Maltsevc, D. V. Marochkina,
V. S. Kochurova, and Academician A. R. Khokhlova
Received March 11, 2013
DOI: 10.1134/S0012500813060050
In recent years, light emitting diodes (LEDs) based cence properties were successfully developed [10–12].
However, the application of these materials was held
up due to complexity of the synthesis.
on conjugated polymers have attracted considerable
attention of researchers owing to their promising
potential as newꢀgeneration fullꢀcolor flatꢀpanel disꢀ
plays [1–6]. An important problem that still remains
unsolved is improving of the external quantum effiꢀ
ciency (EQE) of polymeric lightꢀemitting diodes. The
principle of operation of thinꢀlayer LED structures is
based on electroluminescence (EL) caused by radiaꢀ
tive decay of excitons arising upon recombination of
the electrons and holes injected from opposite elecꢀ
trodes into the polymer layer. Perfect conditions for
producing intense EL and reaching high EQE values
for a polymer are high electron–hole conductivity of
the medium (that is, high mobility of charge carriers)
and maintenance of the balance of injected charge
carriers of different signs from the opposite electrodes
into the material bulk. The mobilities of electrons and
holes should not differ considerably. The main
approach to the improvement of EQE for polymeric
lightꢀemitting diodes is development of luminescent
bipolar (donor–acceptor) polymers [7, 8] where
charge transport and light emission functions are conꢀ
centrated within the same macromolecule. However,
in donor–acceptor polymers, rather strong intramoꢀ
lecular charge transfer (ICT) occurs along the backꢀ
bone, resulting in a decrease in the luminescence
intensity despite better charge transport [7, 8]. An
alternative strategy to overcome this issue is developꢀ
ment of pꢀtype polymers with nꢀtype electronegative
side groups [9]. According to this approach, a number
of conjugated polymers with oxadiazole and quinoxaꢀ
line side groups exhibiting promising electroluminesꢀ
Development of simple methods for the synthesis
of pꢀtype polymers with electronꢀwithdrawing side
groups is quite a topical problem. Meanwhile, pyridinꢀ
2ꢀylimidazo[1,5ꢀ
a]pyridine arouses particular interest
as an ꢀtype electron transporting building block due
n
to high electron affinity, good thermal stability, and
easy synthesis. Presumably, more pronounced elecꢀ
tronꢀwithdrawing properties of the pyridinꢀ2ꢀylimiꢀ
dazo[1,5ꢀa]pyridine ring compared with quinoline or
quinoxaline ring would enhance the electron transport
in polymers. In turn, the introduction of triphenyꢀ
lamine moieties having high hole conductivity and
luminescent properties into conjugated polymer macꢀ
romolecules would improve the electron–hole balance.
Polymers containing triarylamine (TAA) structures
[13, 14] are among the most widely used holeꢀtransꢀ
port materials, because they are readily oxidized to
give stable radical cations. The inclusion of TAA segꢀ
ments into a polymer chains may also improve their
solubility and glass transition temperature. However,
to our knowledge, donor–acceptor polymers with
triphenylamine in the backbone and pyridinꢀ2ꢀylimiꢀ
dazo[1,5ꢀ
a]pyridine in the side chain have been
unknown so far. These facts provide the opportunity to
combine good processability and transport properties
of charge carriers within the same macromolecule
without deteriorating the luminescence efficiency.
This paper reports the synthesis of several new
polyfluorene derivatives with triphenylamine moieties
in the backbone and pyridinꢀ2ꢀylimidazo[1,5ꢀ
a]pyriꢀ
dine side groups having high thermal and oxidative
stability and good mechanical and filmꢀforming propꢀ
erties. The spectral and electroluminescence properties
of LED structures of the obtained polymers were studied.
a Nesmeyanov Institute of Organoelement Compounds,
Russian Academy of Sciences, ul. Vavilova 28, Moscow,
119991 Russia
b National Chiao Tung University, 1000 University Road,
Hsinchu, Taipei, 30010 Taiwan
For the preparation of new copolyfluorenes, bis(4ꢀ
c Frumkin Institute of Electrochemistry, Russian Academy
of Sciences, Leninskii pr. 31, Moscow, 119991 Russia
bromophenyl)ꢀ[4'ꢀ(1''ꢀpyridinꢀ2ꢀylimidazo[1,5ꢀ
a]pyriꢀ
dinꢀ3ꢀyl)pheny]amine ( ) was first synthesized. This
3
165

166
KESHTOV et al.
compound contains triphenylamine groups, which commercially available 4ꢀ(diphenylamino)benzaldeꢀ
enhance the hole transport, and bulky electronꢀwithꢀ hyde and subsequent condensation of the resulting
drawing bipyridyl analogue, namely, pyridinꢀ2ꢀylimiꢀ 4'ꢀbis[(4ꢀbromophenyl)amino]benzaldehyde with
dazo[1,5ꢀ ]pyridine moieties, which increase the 2,2'ꢀdipyridyl ketone and NH4OAc in glacial acetic
electron affinity of the target macromolecular strucꢀ
1
2
a
acid to give target monomer
3
(Scheme 1).
tures. Compound
3 was synthesized by bromination of
NH OAc
Br
1
4
4
4
2
N
Br
N
4'
Br
Br
N
Br
O
CH Cl
2
2
N
N
4'
3
H
O
H
O
2
N
N
1
2
1
1'' N
2''
3
Scheme 1.
The composition and structure of the intermediate 154.77 to 113.83 ppm contains nineteen signals, eight
compounds and target product
3 were confirmed by of these being due to the key quaternary carbon atoms
1
elemental analysis data and H and 13C NMR specꢀ
(Fig. 1b).
The Yamamoto coꢀpolycondensation of the
obtained bipolar aromatic dibromide and 2,7ꢀ
1
troscopy. In particular, the H NMR spectrum of
3
exhibits five doublets, two doublets of doublets, two
triplets, and one multiplet in the lowꢀfield region
3
dibromoꢀ9,9ꢀdioctylfluorene catalyzed by Ni(COD)2
in a toluene–DMF mixture afforded new conjugated
(
δН = 8.7–6.6 ppm), which correspond to phenyl,
pyridyl, and imidazopyridyl protons (Fig. 1a). In the
13C NMR spectrum of product
copolyfluorenes
monomer units: 10, 20, and 50 mol % (Scheme 2).
I–III with different contents of the
3, the range δС of
+
x
Br
Br
Br
N
Br
y
C8H17
H17C8
N
N
N
3
N
x
y
n
(1) Ni(COD)2 + COD
toluene, DMF
C8H17
H17C8
(2)
Br
N
N
N
I: x = 0.9, y = 0.1
II: x = 0.8, y = 0.2
III: x = 0.5, y = 0.5
Scheme 2.
DOKLADY CHEMISTRY Vol. 450
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NEW CONJUGATED ELECTROLUMINESCENT
167
The structures of polymers I–III were confirmed results are summarized in Table 2. The absorption
by 1H NMR data. In the region δH = 8.75–6.73 of the
spectra of copolymers
terns, the peaks being in the range of
As the content of comonomer
increases, the polymer absorption band shifts hypsoꢀ
chromically.
I
–
III (Fig. 3) show similar patꢀ
= 370–387 nm.
in the backbone
1H NMR spectrum, in addition to strong broadened
signals for the fluorene aromatic protons, there are
also wellꢀresolved multiplets centered at δH = 8.30,
8.33, 7.97, and 6.72 ppm, which are due to the monoꢀ
λ
3
mer units of
results confirm that the triphenylamine and pyridinꢀ2ꢀ
ylimidazo[1,5ꢀ ]pyridine moieties were successfully
introduced in the polymer chain. The δH = 2.11, 1.13,
and 0.80 ppm signals correspond to the aliphatic proꢀ
tons of the octyl groups in position 9 of the fluorene
unit. The integrated intensity ratio of the aromatic and
aliphatic protons corresponds to the assumed strucꢀ
tures for all polymers and confirms the required conꢀ
3 present in the chain (Fig. 2). These
The forms and positions of the bands are apparꢀ
ently related to lowꢀenergy
π
ꢀπ∗ electron transitions
a
in the polyconjugated macromolecular chain. The
abs
shortꢀwavelength shift relative to that of HPF (
λmax
=
390 nm) is due to substituents that affect the polyconꢀ
jugation length of copolymers III, particularly,
I–
somewhat decrease the polyconjugation length comꢀ
pared with the parent polyfluorene.
tent of unit
monomer units
20.8, and 51.1 mol. %, respectively, as found from the
data of elemental analysis.
3
in the backbone. The mole percents of
in polymers II, and III are 10.1,
All polymers I–III exhibit intense photoluminesꢀ
3
I,
cence (PL), which is manifested as two bands in the
blue region, which do not differ much from those in
the fluorescence spectrum of HPF and have maxima
at 417–419 and 433–442 nm (which are also the same
as for HPF). Their structure does not practically
change upon excitation of the system either at the
absorption maximum or at a shorter wavelength, i.e.,
in the absorption region of substituents. These bands
should be assigned to 0–0, 0–1, and 0–2 intrachain
singlet transitions in HPF. Thus, nonradiative transfer
of the excitation energy to the polyconjugated chain
occurs in the macromolecular system, apparently,
according to the Forster mechanism, because the
absorption and PL spectra substantially overlap, which
All polymers are soluble in common organic solꢀ
vents such as DMF, DMSO, THF, dimethylacetꢀ
amide, toluene, and chloroform. Films with tensile
strength of 83–90 MPa (Table 1) were obtained from
the solutions. The numberꢀ and weightꢀaverage
molecular weights and polydispersities of polymers
III determined by gel permeation chromatography
(elution with THF) vary in the ranges of (2.19–4.17)
104 (Mn 104 (Mw), and 1.89–2.03,
, (4.14–8.46)
respectively.
I–
×
)
×
The thermal and thermooxidative characteristics of
copolyfluorenes III were studied by thermomeꢀ
chanical (TMA) and thermogravimetric (TGA) analꢀ
yses; the results are summarized in Table 1. All polyꢀ
mers exhibit high thermal stability. The glass transition
is true for all of copolymers
I–III. The introduction of
I–
monomer unit has almost no influence on the posiꢀ
3
tions of the principal PL bands of the copolyfluorenes,
and only a considerable increase in the intensity of the
longerꢀwavelength band compared to the shorterꢀ
wavelength band occurs upon increase in the molar
temperatures of copolymers (Tg) found from TMA
data are between 103 and 200°C. The temperatures of
10% weight loss (Т10%) determined by TGA in air and
under argon are in the ranges of 401–422 and 409–
content of the monomer units
From the onset of absorption spectra of
solution ( ads ), the optical width of the forbidden gap
3.
I–III in
445
introduction of bipolar heteroaromatic units into the
polymer chain results in higher g and higher thermal
stability of the copolyfluorenes compared with
homopolyfluorene (HPF) ( g = 66 C, Т10% = 410°C),
and these values tend to increase with an increase in
the molar content of monomer units in the backꢀ
bone. The introduction of 50 mol. % of monomer
units into the polyfluorene chain made the largest
°
C, respectively. It follows from Table 1 that the
λons
opt ) was calculated; the results are presented in
(
Eg
T
Table 2. The band gap of the polymers in question
remains almost invariable upon changes in the strucꢀ
T
°
ture and molar amount of comonomer
the polyfluorene backbone.
3
introduced in
3
The electrochemical properties of
I–III were studꢀ
3
ied by cyclic voltammetry; the results are also preꢀ
sented in Table 2. The cyclic voltammograms of the
copolymers exhibit anodic oxidation peaks at positive
voltage; no cathodic reduction peaks are present at
negative voltage. From the potential of the onset of
ox
contribution to the increase in the glass transition
temperature of polymer III, which becomes as high
as 200 C with simultaneous maximum increase in the
°
thermal stability with respect to other copolymers synꢀ
thesized.
oxidation (
), the energies of the highest occupied
λons
III were molecular orbital (HOMO) for
studied by UV and fluorescence spectroscopy; the found in the following way:
The optical properties of polymers
I–
I–III (Table 2) were
DOKLADY CHEMISTRY Vol. 450
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168
KESHTOV et al.
b
a
a
b
Br
N
Br
(a)
c
d
d, h
l
N
N
k
j
c
N
i
e
h
f
g
е, i
k
e
l
CDCl3
g
j
8.8
8.4
5
8.0
7.6
7.2
6.8
6.4
Н, ppm
δ
1
4
(b)
14
15
9
16
8
2
3
1
4
Br
20
N
5
Br
17
6
19
7
11
18
12
8
10
13
9
10
N
N
11
12
15
14
N
16
13
20
17
7
6
19
18
2
3
154
146
138
130
122
114
С, ppm
δ
1
13
Fig. 1. (a) H NMR and (b) C NMR spectra of bis(4ꢀbromophenyl)ꢀ[4'ꢀ(1''ꢀpyridinꢀ2''ꢀylimidazo[1,5ꢀ
nyl]amine in CDCl .
a]pyridinꢀ3ꢀyl)pheꢀ
3
3
DOKLADY CHEMISTRY Vol. 450
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NEW CONJUGATED ELECTROLUMINESCENT
169
Alk
N
x
n
y
C8H17
H17C8
N
N
N
I
x : y = 0.9 : 0.1
Ar
9.0 8.5 8.0 7.5 7.0 6.5
9
8
7
6
5
4
3
2
1
0
H, ppm
δ
1
Fig. 2. H NMR spectrum of copolymer I in CDCl .
3
EHOMO = EFHcOMO + e(E ox – E ox
– Eel),
ons(Fc)
The EL spectra of copolyfluorenes
broad intense bands with peaks at 476 and 469 nm,
respectively (Fig. 3), which corresponds to blue radiaꢀ
I and II are
ons
HOMO
Fc
ox
where
= –4.8 eV,
= 0.21 eV,
=
E
Eel
E
ons(Fc)
tion with color coordinates
Table 3). An increase in the content of monomer
units in the macromolecule entails a slight hypsofluꢀ
oric shift of the principal EL band (by 7 nm for copolꢀ
ymers and II).
x = 0.191, y = 0.249 (for I,
0.23 eV (found from cyclic voltammetry data for ferꢀ
rocene used as the standard). Thus, HOMO = –4.36 eV +
E
3
ox
. The lowest unoccupied molecular orbital (LUMO)
eE
ons
LUMO
opt . It
= EHOMO + Eg
I
energies were calculated as
E
follows from Table 2 that the HOMO energy of
gradually increases with increase in the content of
monomer units
I–III
The brightness of devices based on copolymers
I
and II and on previously prepared HPF (used for
comparison) was measured to characterize the emisꢀ
sion properties of the LED structures. The depenꢀ
dence of brightness on the applied voltage is presented
in Fig. 4b.
3.
In order to study the effect of monomer units
3
introduced into the polyfluorene backbone on the
electroluminescence properties of the obtained copolꢀ
ymers, LED structures with a hole injection layer
based on a dispersion of polyethylenedioxythiophene
stabilized by polystyrene sulfonate (PEDOT/PSS)
and a thin electron injection layer based on lithium
fluoride were fabricated. On voltage application on the
LED structures, blue EL was observed (Fig. 3) with
color coordinates given in Table 3 and in Fig. 4a. The
EL spectra are shifted to longer wavelengths relative to
PL bands, which is usual for organic materials.
It follows from the data that a device based on the
active layer consisting of pure HPF has a brightness of
1.4 Cd/m2 at 10 V. Light emitting diodes based on
copolymers
7.3 Cd/m2 at the same voltage. The introduction of 10
and 20 mol. % of monomer units into the HPF strucꢀ
I and II had brightnesses of 5.9 and
3
ture increased the brightness of emission 4.2ꢀ and
5.2ꢀfold, respectively.
DOKLADY CHEMISTRY Vol. 450
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170
KESHTOV et al.
Table 1. Molecularꢀweight and thermal characteristics of copolyfluorenes
I
–III
Film properties
, MPa , %
Polymer
Mn
×
10–4
Mw
×
10–4
Mw
/
Mn
Тg
,
°
C
Т10%, °C*
σ
ε
401
ꢀꢀꢀꢀꢀꢀ
I
4.17
2.19
2.78
8.46
4.14
5.39
2.03
1.89
1.94
103
174
200
89
83
90
6
7
5
409
412
ꢀꢀꢀꢀꢀꢀ
II
III
426
422
ꢀꢀꢀꢀꢀꢀ
445
* In air, above the line, and under argon, below the line.
Table 2. Optical and electrochemical properties of copolyfluorenes I–III
abs
max
PL
max
abs
ons
Eogpt
EHOMO
ELUMO
*
l
l
l
Eooxns , V
Polymer
nm
eV
I
II
III
387
382
370
419; 440
419; 442
417; 433
415
418
420
1.28
1.15
1.10
–5.64
–5.51
–5.46
–2.65
–2.54
–2.51
2.99
2.97
2.95
* The LUMO values were found from the difference of Eogpt and E
.
HOMO
Thus, we synthesized electroactive polymers of a broad range of metal ions and are attractive as recogꢀ
nition receptors. Thus, copolyfluorenes I–III can also
be used as chemosensors for various analytes.
new type having photoꢀ and electroluminescence
properties incorporating donor–acceptor groups as
functional substituents. The partial replacement of
dialkylfluorene by the multifunctional monomer unit
3
EXPERIMENTAL
Synthesis of Monomers
in the copolyfluorene backbone gave rise to some
advantages, in particular, higher thermal and chemical
stability, higher electron affinity within the same molꢀ
4'ꢀBis[(4ꢀbromophenyl)amino]benzaldehyde
(2)
ecule without deterioration of the emission properties was prepared by a reported procedure [15]. Yield 5.38 g
(72%). Mp = 152–154°C; lit. [15]: Mp = 156–157°C.
1H NMR (CDCl3, 400 MHz,
, ppm): 9.82 (s, 1H),
7.70 (d, = 8.8 Hz, 2H), 7.43 (dd, = 9.3, 2.5 Hz,
4H), 7.06–6.98 (m, 6H).
13C NMR (CDCl3, 100 MHz,
of polyfluorenes, considerable improvement and
extension of electronꢀtransport and electroluminesꢀ
cence properties. Moreover, replacement of alkyl subꢀ
stituents by bulky heteroaromatic moieties reduces the
aggregation and phase separation, which are inherent
in poly(dialkylfluorene) macromolecules in the proꢀ
duction of such devices. The electroactive conjugated
copolyfluorenes based on bipolar monomers can serve
as effective electroluminescence materials in polyꢀ
δ
J
J
δ
, ppm): 190.29,
152.22, 144.87, 132.80, 131.26, 129.99, 127.26,
120.29, 117.95.
For C19H13Br2NO anal. calcd. (%): C, 52.93;
meric LEDs. Moreover, pyridinꢀ2ꢀylimidazo[1,5ꢀ H, 3.04; N, 3.25; Br, 37.07.
a
]pyridine moieties contained in copolymers I–III,
Found (%): C, 52.72; H, 2.99; N, 3.32; Br, 37.25.
like 2,2'ꢀbipyridine, exhibit chelating ability towards a
Bis(4ꢀbromophenyl)ꢀ[4'ꢀ(1''ꢀpyridinꢀ2''ꢀylimiꢀ
dazo[1,5ꢀa]pyridinꢀ3ꢀyl)phenyl] amine (3). 2,2'ꢀBipyꢀ
ridyl ketone (0.21 g, 1.16 mol) and glacial acetic acid
(7.0 mL) were charged into a 25 mL threeꢀnecked
roundꢀbottom flask equipped with a reflux condenser,
argon inlet, and a magnetic stirrer. The mixture was
stirred at room temperature until the solid completely
dissolved, and 4'ꢀbis[(4ꢀbromophenyl)amino]benzalꢀ
dehyde 2 (1.0 g, 2.32 mmol) and NH4OAc (0.45 g,
5.80 mmol) were added. The reaction mixture was
stirred at 80°C under argon for 1.5 h and cooled to
Table 3. Electroluminescence properties of copolyfluoꢀ
renes I–III
Color coordinates
lemlax , nm
Polymer
x
y
I
476
470
462
0.191
0.206
0.213
0.249
0.309
0.348
II
III
DOKLADY CHEMISTRY Vol. 450
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NEW CONJUGATED ELECTROLUMINESCENT
171
1.0
1.0
3
4
5
1
0.5
0.5
2
2
1
'
'
3
'
0
300
0
600
350
400
450
, nm
500
550
λ
Fig. 3. Absorption spectra of polymers (
1
)
I
, (
2
)
II, and (
3
)
III; photoluminescence spectra of (
1')
I, (2
') II, and (
3
') III in chloꢀ
–5
roform (
с
= 1
×
10 mol/L); and electroluminescence spectra of (4) I and (5) II in a film.
y
0.8
20
15
10
5
(a)
(b)
II
I
0.6
0.4
0.2
HPF
0
0
0.1
0.3
0.5
0.7
5
10
15
Voltage, V
x
Fig. 4. (a) Color coordinates of a light emitting diode device based on polymer II and (b) brightness of the electroluminescence
of copolymers and II and homopolyfluorene (HPF) vs. applied voltage.
I
room temperature. The mixture was poured into 8.7 Hz, 4H), 7.18 (d,
J
= 8.5 Hz, 2H), 7.12 – 7.05 (m,
1H), 7.00 (d,
6.5 Hz, 1H), 6.64 (t,
J
= 8.7 Hz, 4H), 6.91 (dd,
= 6.7 Hz, 1H).
J = 9.0,
100 mL of ice water and extracted with CH2Cl2. The
organic layer was washed with doubly distilled water,
dried with MgSO4, and concentrated on a rotary evapꢀ
orator. The product was purified by column chromaꢀ
tography (elution with toluene : ethyl acetate = 1 : 1)
to give yellow crystals. Yield 0.57 g (82%). Mp = 174–
175°C.
J
13C NMR (CDCl3, 100 MHz,
, ppm): 154.77,
148.82, 147.32, 145.91, 137.54, 136.14, 132.43,
130.04, 129.29, 125.87, 124.52, 123.81, 121.78,
121.48, 120.88, 120.34, 119.77, 116.13, 113.83.
δ
For C30H20N4Br2 anal. calcd. (%): C, 60.42;
H, 3.38; N, 9.40.
1H NMR (CDCl3, 400 MHz,
=9.2 Hz, 1H), 8.61 (d, = 4.2 Hz, 1H), 8.23 (dd,
7.4, 3.5 Hz, 2H), 7.70 (t, =8.6 Hz, 3H), 7.38 (d,
δ
, ppm): 8.70 (d,
J
J
J
J
J
=
=
Found (%): C, 60.69; H, 3.27; N, 9.07.
DOKLADY CHEMISTRY Vol. 450
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KESHTOV et al.
Synthesis of Copolymers
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equipped with a reflux condenser, a magnetic stirrer,
and argon inlet was charged with Ni(COD)2 (1.000 g,
3.636 mmol), 2,2'ꢀbipyridine (0.5600 g, 3.636 mmol),
and 1,5ꢀcyclooctadiene (0.3933 g, 3.636 mmol). Dry
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,
at 80
dioctylfluorene (0.7898 g, 1.44 mmol) and bis(4ꢀbroꢀ
mophenyl)ꢀ[4'ꢀ(1''ꢀpyridinꢀ2''ꢀylimidazo[1,5ꢀ ]pyridinꢀ
3ꢀyl)phenyl]amine ( ) (0.095 g, 0.16 mmol) in a 4 : 1
toluene–DMF mixture (12.5 mL) was added through
a septum. The mixture was stirred at 80 for 48 h, and
°
C for 30 min. A solution of 2,7ꢀdibromoꢀ9,9ꢀ
4. Chen, B.Z., Wu, Y.Z., Wang, M.Z., et al., Eur. Polym. J.,
2004, vol. 40, no. 6, pp. 1183–1191.
a
5. Keshtov, M.L., Mal’tsev, E.I., Marochkin, D.V.,
Pozin, S.I., Lypenko, D.A., Perevalov, V.P., Petroꢀ
vskii, P.V., and Khokhlov, A.R., Dokl. Chem., 2011,
vol. 439, part 1, pp. 175–180.
3
°С
bromobenzene (0.06 g, 0.39 mmol) was added. The
mixture was stirred for more 5 h, cooled to room temꢀ
perature, and poured into a 2 : 1 methanol–concenꢀ
trated HCl mixture (250 mL). The precipitate was filꢀ
tered off, dissolved in chloroform, and reprecipitated
with methanol. The polymer was purified by methanol
and acetone extraction in a Soxhlet apparatus for 24 h
and dried in vacuum at 70°C. Yield 75%.
6. Keshtov, M.L., Pozin, S.I., Marochkin, D.V., Pereꢀ
valov, V.P., Petrovskii, P.V., Blagodatskikh, I.V., and
Khokhlov, A.R., Dokl. Chem., 2012, vol. 442, part 2,
pp. 23–29.
7. Jenekhe, S.A., Lu, L., and Alam, M.M., Macromoleꢀ
cules, 2001, vol. 34, no. 21, pp. 7315–7324.
8. Yamamoto, T., Yasuda, T., Sakai, Y., and Aramaki, S.,
Macromol. Rapid Commun., 2005, vol. 26, no. 15,
pp. 1214–1217.
9. Kulkarni, A.P., Tonzola, C.J., Babel, A., and
Jenekhe, S.A., Chem. Mater., 2004, vol. 16, no. 23,
pp. 4556–4573.
1H NMR (CDCl3, 400 MHz, δН, ppm): 8.75–7.73
(m, Ar H), 2.93–0.48 (m, Alk H).
For I anal. calcd. (%): C, 88.55; H, 9.66; N, 1.79.
Found (%): C, 88.19; H, 9.71; N, 1.63.
10. Shi, W., Wang, L., Zhen, H., Zhu, D., Awut, T., Mi, H.,
and Nurulla, I., Dyes Pigm., 2009, vol. 83, pp. 102–110.
Copolymers II and III were synthesized in a similar
way.
11. Chen, S.Y., Xu, X.J., Liu, Y.Q., Qiu, W.F., Yu, G.,
Wang, H.P., and Zhu, D.B., J. Phys. Chem. C, 2007,
vol. 111, no. 2, pp. 1029–1034.
12. Hancock, J.M., Gifford, A.P., Zhu, Y., Lou, Y., and
Jenekhe, S.A., Chem. Mater., 2006, vol. 18, no. 20,
pp. 4924–4932.
1
Copyfluorene II. Yield 81%. H NMR (CDCl3,
400 MHz, δН, ppm): 8.72–7.68 (m, Ar H), 2.97–0.52
(m, Alk H).
For II anal. calcd. (%): C, 88.06; H, 9.04; N, 2.90.
13. Shi, W., Fan, S.Q., Huang, F., Yang, W., Liu, R.S., and
Cao, Y., J. Mater. Chem., 2006, vol. 16, pp. 2387–2394.
14. Xiao, H.B., Leng, B., and Tian, H., Polymer, 2005,
vol. 46, no. 15, pp. 5707–5713.
15. Lee, S.K., Hwang, D.ꢀH., Jung, B.ꢀJ., et al., Adv.
Funct. Mater., 2005, vol. 15, no. 10, pp. 1647–1655.
Found (%): C, 87.82; H, 9.18; N, 2.78.
1
Copyfluorene III. Yield 77%. H NMR (CDCl3,
400 MHz, δН, ppm): 8.73–7.75 (m, Ar H), 2.94–0.50
(m, Alk H).
For III anal. calcd. (%): C, 85.87; H, 7.27; N, 6.86.
Found (%): C, 85.36; H, 7.36; N, 6.72.
Translated by Z. Svitanko
DOKLADY CHEMISTRY Vol. 450
Part 2
2013