Communication

1704

Summary: A kind of novel dibromocarbazole monomer

bearing three alkyl chains was prepared. Two strategies were
developed to improve the solubility and molecular weight of
carbazole polymers. One was the polymerization of N-octyl2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole with the alkylated dibromocarbazole. Another one was
the polymerization of N-octyl-2,7-bis(4,4,5,5-tetramethyl1,3,2-dioxaborolan-2-yl)carbazole with N-octyl-3,6-dibromocarbazole. All the polymerizations were carried out under
palladium-catalyzed Suzuki polycondensation (SPC) conditions. Through using carbazole monomer bearing three
alkyl chains to polymerize, we have successfully boosted the
number-average molecular weight of 2,7-linked carbazole
polymers from not more than 5 to 67 kDa. The highmolecular-weight polymers were obtained in high yields and
displayed good solubility in common organic solvents. Their
optical, electrochemical, and thermal properties were also
reported.

Preparation of carbazole polymers by Suzuki polycondensation.

Synthesis, Optical, and Electrochemical Properties of the

High-Molecular-Weight Conjugated Polycarbazoles
Yaqin Fu, Zhishan Bo*
State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences,
Beijing 100080, China
Fax: (86) 10 82618587; E-mail: zsbo@iccas.ac.cn

Received: July 7, 2005; Revised: August 24, 2005; Accepted: August 29, 2005; DOI: 10.1002/marc.200500478
Keywords: chain; high molecular weight; poly(2,7-carbazole)s; Suzuki polycondensation; synthesis

Introduction
The recent development of conjugated polymers has
received much attention because of their potential applications in light-emitting diodes (LEDs),[1] solar cells,[2]
sensors,[3] etc. Interest in the carbazole-based conjugated
polymers and oligomers arises mainly from their useful
applications as photoconductors,[4,5] photorefractive materials,[4,5] hole-transporting materials,[6] light-emitting
materials,[7] and host materials for triplet emitters.[8] Many
attempts have been devoted to synthesize carbazole-based
polymers, and most polymers are based on the 3,6linkage.[9,10] For example, Iraqi and Wataru reported the
preparation of 3,6-linked carbazole polymers by coupling
Macromol. Rapid Commun. 2005, 26, 17041710

of N-alkyl-3,6-dihalocarbazole (Br and I) in the presence of

magnesium and (2,2-bipydine)dichloro palladium.[9b] The
number-average molecular weight of the polymers was in
the range of 25 kDa. Strohriegl and colleagues have
reported that a limiting factor in the synthesis of highmolecular-weight poly(N-alkyl-3,6-carbazole)s is the formation of low-molar-mass cyclic oligomers.[10] Recently,
Li et al. reported the synthesis and light-emitting properties
of random and alternating fluorine carbazole polymers,[11]
Zhang et al. have successfully prepared the high-molecularweight poly(N-alkyl-3,6-carbazole)s and the optically
active poly(3,6-carbazole)s by using a reverse addition
order for the zerovalent nickel reagent based on the
Yamamoto coupling reaction.[12] Carbazole polymers

DOI: 10.1002/marc.200500478

2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Synthesis, Optical, and Electrochemical Properties of the High-Molecular-Weight Conjugated Polycarbazoles

based on 2,7-linkage have received particular attention

because they could offer a higher degree of conjugation than
the polymers based on the 3,6-linkage. The first 2,7carbazole homopolymers and copolymers were prepared by
Morin and Leclerc using Yamamoto coupling, Suzuki
coupling, and Stille coupling.[13] The 2,7-carbazole homopolymers obtained by Yamamoto coupling method were
only partially soluble in common organic solvents, such as
chloroform and THF. The number-average molecular
weight [measured by gel permeation chromatography
(GPC) against polystyrene standards] of the soluble part
was about 5 kDa with a polydispersity of around 1.5.
Poly(N-octyl-2,7-carbazole-alt-9,9-dioctyl-2,7-fluorene)s
prepared by Suzuki coupling were soluble in the abovementioned organic solvents, but their number-average
molecular weight was also around 5 kDa. Using similar
method, Iraqi et al. synthesized 2,7-linked carbazole
polymers with the number-average molecular weight in
the range from 2 to 5 kDa. In order to improve the molecular
weight of 2,7-linked carbazole polymers, Morin and
Leclerc[7] used the reverse addition method suggested by
Zhang et al. in the synthesis, but this method did not lead to
any increase of the molecular weight.
In this communication, we report two strategies to
synthesize high-molecular-weight soluble conjugated carbazole polymers. Novel 2,7-dibromocarbazole monomer
bearing three alkyl chains was synthesized and used to
polymerize with N-octyl-2,7-carbazolediboronic pinacol
ester. The introduction of alkyl chains onto carbazole ring
could significantly improve the solubility of the 2,7-linked
carbazole polymers in common organic solvents and the
number-average molecular weight. The polymerization of
N-octyl-2,7-carbazolediboronic pinacol ester with N-octyl3,6-dibromocarbazole could also give soluble high-molecular-weight polymers. Suzuki polycondensation (SPC) was
used to polymerize these monomers, and the influence of
the structure of monomers on the molecular weight of
polymers was investigated. In addition, the optical, electrochemical, and thermal properties of the carbazole polymers
were also reported.

Experimental Part
4-Bromo-1-iodo-2-nitrobenzene,[14] 4-bromo-2,5-di-n-hexylbenzeneboronic acid,[15] N-octyl-2,7-bis(4,4,5,5-tetramethyl1,3,2-dioxaborolan-2-yl)carbazole,[16] N-octyl-3,6-dibromocarbazole,[11] N-octyl-3,6-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole,[11] poly(N-octyl-3,6-carbazole),[17]
and poly(N-octyl-2,7-carbazole) (5)[7] were synthesized
according to the literature procedures. All the chemicals were
purchased from Acros and used as received. The 1H and 13C
NMR spectra were recorded on an AV400 or DM300
spectrometer in CDCl3. The GPC measurements were
performed on Waters 410 system against polystyrene standards
with THF as an eluent. UV-visible absorption spectra were
obtained on a SHIMADZU UV-visible spectrometer model
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UV-1601PC. Fluorescence emission spectra were recorded in

THF at 293 K with a HITACHI F4500 fluorescence spectrophotometer. Fluorescence quantum yields (FF) of the samples
in toluene were measured by using 9,10-diphenylanthracene
(FF 0.9 in toluene) as standard. The electrochemical
experiments were performed on CHI 630A Electrochemical
Analyzer in acetonitrile at a glassy carbon or ITO glass
working electrode in a three-electrode cell with a Pt wire
counter electrode and an Ag/Ag reference electrode. The
films on the work electrodes for cyclic voltammetry (CV)
investigation were deposited by casting from chloroform
solution.
4-Bromo-2-nitro-20 ,50 -di-n-hexyl-40 -bromobiphenyl (1)
A mixture of 4-bromo-1-iodo-2-nitrobenzene (4.8 g,
14.7 mmol), 4-bromo-2,5-dihexylphenylboronic acid (5.0 g,
13.4 mmol), NaHCO3 (15 g, 0.12 mol), THF (115 mL), and
H2O (45 mL) was degassed and Pd(PPh3)4 (0.15 g, 0.13 mmol)
was added under nitrogen atmosphere. The reaction mixture
was heated at 50 8C and stirred under nitrogen for 6 d. CH2Cl2
(200 mL) and H2O (50 mL) were added to dissolve the formed
precipitate. The organic layer was separated, the aqueous one
extracted with CH2Cl2 (
3), and the combined organic phase
dried over Na2SO4. After removal of the solvent, the crude
product was purified by flash column chromatography eluting
with petroleum ether to afford compound 1 as a yellow oil
(4.5 g, 66%).
1
H NMR (400 MHz, CDCl3): d 8.13 (s, 1H), 7.73 (d, 1H,
J 8.7 Hz), 7.44 (s, 1H), 7.19 (d, 1H, J 8.2 Hz), 6.86 (s, 1H),
2.67 (t, 2H, J 7.8 Hz), 2.31 (m, 2H), 1.53 (m, 2H), 1.32
(m, 2H), 1.29 (m, 6H), 1.14 (m, 6H), 0.85 (m, 6H).
13
C NMR (75 MHz, CDCl3): d 149.3, 139.5, 135.4, 135.1,
134.4, 133.6, 133.1, 129.9, 127.2, 124.6, 121.6, 35.6, 32.6,
31.6, 31.4, 30.3, 29.7, 29.1, 22.6, 22.4, 14.0.
Anal. Calcd. for C24H31Br2NO2: C 54.87, H 5.95, N 2.67;
Found: C 55.18, H 6.04, N, 2.35.
2,7-Dibromo-1,4-dihexylcarbazole (2)
A mixture of 1 (1.5 g, 2.9 mmol) and triethylphosphite (20 mL)
was heated to reflux and stirred at nitrogen atmosphere for 24 h.
The excess of triethylphosphite was removed under reduced
pressure and the crude product was purified by flash column
chromatography eluting with CH2Cl2/petroleum ether (1:2) to
provide 2 as a white solid (0.6 g, 43%). m.p. 120121 8C.
1
H NMR (300 MHz, CDCl3): d 8.06 (s, 1H), 7.86 (d, 1H,
J 8.4 Hz), 7.62 (s, 1H), 7.37 (d, 1H, J 8.0 Hz), 7.22 (s, 1H),
3.08 (t, 2H, J 7.8 Hz), 2.97 (t, 2H, J 8.0 Hz), 1.75 (m, 2H),
1.66 (m, 2H), 1.47 (m, 6H), 1.35 (m, 6H), 0.88 (m, 6H).
13
C NMR (100 MHz, CDCl3): d 140.2, 139.2, 137.1,
124.7, 123.5, 123.1, 122.5, 122.0, 121.5, 119.8, 118.9, 113.7,
33.8, 31.8, 31.3, 29.5, 29.4, 28.9, 22.7, 22.6, 14.1.
Anal. Calcd. for C24H31Br2N: C 58.43, H 6.33, N 2.84;
Found: C 58.50, H 6.40, N 2.87.
2,7-Dibromo-1,4-dihexyl-N-octylcarbazole (3)
Compound 3 was prepared as a white solid in a yield of 87%
according to the literature procedures.[18] m.p. 5758 8C.
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H NMR (400 MHz, CDCl3): d 7.89 (d, 2H, J 8.4 Hz),

7.54 (s, 1H), 7.35 (d, 1H, J 8.3 Hz), 7.27 (s, 1H), 4.32 (t, 2H,
J 8.1 Hz), 3.15 (t, 2H, J 8.2 Hz), 3.08 (t, 2H, J 7.8 Hz),
1.80 (m, 4H), 1.67 (m, 2H), 1.521.30 (m, 22H), 1.00 (m, 9H).
13
C NMR (100 MHz, CDCl3): d 142.21, 139.15, 136.90,
125.01, 124.11, 123.50, 122.51, 122.32, 121.49, 120.89,
119.00, 111.94, 45.22, 33.84, 31.87, 31.74, 31.72, 31.60,
30.74, 30.10, 29.45, 29.41, 29.27, 29.21, 29.16, 26.84, 22.67,
22.61, 14.07, 14.05.
Anal. Calcd. for C32H47Br2N: C 63.47, H 7.82, N 2.31;
Found: C 63.48, H 7.87, N 2.37.
Polymer 6
A mixture of N-octyl-3,6-dibromocarbazole (0.08 g,
0.19 mmol), N-octyl-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole (0.1 g, 0.19 mmol), NaHCO3 (0.4 g,
4.8 mmol), THF (15 mL), and H2O (4 mL) was degassed and
Pd(PPh3)4 (4 mg, 0.003 mmol) was added under nitrogen
atmosphere. The reaction mixture was heated at reflux and
stirred under nitrogen for 48 h. The formed precipitate was
collected by filtration, dissolved in THF, and filtered through a
short pad of silica gel column eluting with THF. The filtrate was
concentrated to 5 mL, precipitated into methanol (50 mL), the
formed precipitate collected by filtration, and dried under
vacuum to give 6 (0.09 g, 82%) as a yellow solid.
1
H NMR (300 MHz, CDCl3): d 8.55 (broad, 2H), 8.19
8.15 (broad, 2H), 7.88 (broad, 2H), 7.73 (broad, 2H), 7.66
7.60 (broad, 2H), 7.527.47 (broad, 2H), 4.474.30 (broad,
4H), 1.96 (broad, 4H), 1.461.23 (broad, 20H), 0.880.78
(broad, 6H).
13
C NMR (75 MHz, CDCl3): d 141.6, 140.3, 139.9, 133.5,
125.9, 123.6, 121.4, 120.5, 119.4, 119.0, 109.1, 107.3, 43.4,
31.8, 29.4, 29.2, 27.4, 22.6, 14.0, 1.0.
Anal. Calcd for [C40H46N2]n: C 86.59, H 8.36, N 5.05;
Found: C 83.91, H 8.27, N 5.00.
Polymer 7
A mixture of compound 3 (0.12 g, 0.19 mmol), N-octyl2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole
(0.1 g, 0.19 mmol), NaHCO3 (0.4 g, 4.8 mmol), THF (15 mL),
and H2O (4 mL) was degassed and Pd(PPh3)4 (4 mg,
0.003 mmol) was added under nitrogen atmosphere. The reaction mixture was heated at reflux and stirred under nitrogen for
3 d. The formed precipitate was collected by filtration, dissolved in THF, and filtered through a short pad of silica gel column
eluting with THF. The filtrate was concentrated to 5 mL,
precipitated into methanol (50 mL), the formed precipitate
collected by filtration, and dried under vacuum to give 7 (0.12 g,
87%) as a yellow solid.
1
H NMR (300 MHz, CDCl3): d 8.288.19 (broad, 3H),
7.797.68 (broad, 4H), 7.517.47 (broad, 1H), 7.337.31
(broad, 1H), 7.09 (broad, 1H), 4.564.47 (broad, 4H), 3.29
3.00 (broad, 4H), 2.031.61 (broad, 6H), 1.401.16 (broad,
34H), 0.950.75 (broad, 12H).
13
C NMR (75 MHz, CDCl3): d 142.0, 141.2, 140.4, 138.9,
134.6, 120.9, 120.8, 118.8, 110.0, 107.7, 31.4, 31.1, 29.3, 29.0,
28.9, 27.1, 26.6, 22.3, 22.2, 22.1, 13.7, 13.5.
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Anal. Calcd. for [C52H70N2]n: C 86.37, H 9.76, N 3.87;

Found: C 82.98, H 9.61, N 3.82.

Results and Discussion

Monomer Synthesis
The synthetic route leading to carbazole monomer bearing
alkyl chains is outlined in Scheme 1. Starting from
commercially available 4-bromo-1-iodo-2-nitrobenzene,
its coupling with 4-bromo-2,5-dihexylphenylboronic acid
in a biphasic mixture of THF and aq. NaHCO3 with
Pd(PPh3)4 as the catalyst precursor gave 1 in a yield of 66%.
A reductive Cadogan ring closure of 1 via refluxing with
P(OEt)3 gave carbazole 2 in a 43% yield. Following a
procedure suggested by Leclerc and colleagues, alkylation
of the N-position was achieved.[13] Monomer 3, which
exhibited very good solubility in common organic solvents,
was obtained in a yield of 87%. The purity of 3 was
confirmed by 1H and 13C NMR spectroscopy and elemental
analysis.

Synthesis and Characterization of the Polymers

Scheme 1 depicts the synthetic route to the carbazole
polymers 47. Palladium-catalyzed SPC was used to
prepare the target polymers. In order to achieve highmolecular-weight soluble carbazole polymers, we have
screened four groups of reactions. The preparation of 3,6linked and 2,7-linked carbazole polymers (4 and 5) has been
reported in the literature.[7,11] Here we used SPC to
synthesize these two polymers, as shown in Scheme 1.
Polymer 4 was prepared by SPC of N-octyl-3,6-dibromocarbazole and N-octyl-3,6-bis(4,4,5,5-tetramethyl-1,3,2dioxaborolan-2-yl)carbazole and polymer 5 was prepared
by SPC of N-octyl-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole and N-octyl-2,7-dibromocarbazole. Both 4 and 5 we prepared were only partially
soluble in common organic solvents, such as CH2Cl2,
CHCl3, and THF, and their molecular weights were also
relatively low (see Table 1). The polymerization of N-octyl3,6-dibromocarbazole with N-octyl-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole under the standard SPC conditions gave polymer 6 in a yield of 82%.
Polymer 6 was fully soluble in common organic solvents
mentioned above, and its number-average molecular
weight reached 14.9 kDa. According to the hair-rod model
suggested by Wegner et al.,[19] the introduction of flexible
alkyl chains on the carbazole ring should increase the
solubility of the corresponding polymers, and thus highmolecular-weight polymers should be prepared. Coupling
of the alkylated carbazole monomer 3 with N-octyl-2,7bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole
gave polymer 7 in a yield of 87%. During the reaction,
2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Synthesis, Optical, and Electrochemical Properties of the High-Molecular-Weight Conjugated Polycarbazoles

Scheme 1.

polymers 6 and 7 started to precipitate from the reaction

system in about 10 and 5 h, respectively, but the formed
precipitates could be easily redissolved in pure THF.
Reprecipitation with methanol to remove the lower
molecular weight oligomers and freeze-drying from
benzene afforded the pure polymers 6 and 7 as amorphous
yellow solids. The structures of polymers 6 and 7 were

proved by 1H and 13C NMR spectroscopy and combustion

analysis. For a comparison, the molecular weights and
polydispersities of polymers 47 are summarized in
Table 1. The number-average molecular weight of polymer
7 was up to 67 kDa.

Optical Properties
Table 1. Molecular weights, polydispersities, and fluorescence
quantum yields of the polymers.
Polymer
4
5
6
7

Mn

Mw

M w =M n

FF

3 900
6 400
14 900
67 000

5 200
9 000
25 000
82 600

1.31
1.41
1.69
1.23

0.90
0.65
0.94

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Figure 1(a) shows the absorption and photoluminescence

spectra of polymers 57 in THF solution at room
temperature. Polymer 5 absorbed in ultraviolet region
peaked at about 384 nm. Polymer 6 showed a broader
absorption band with the maximum at about 357 nm and
polymer 7 exhibited a narrower absorption band with the
absorption maximum at about 362 nm. Compared with
polymer 5, the absorption maxima of polymers 6 and 7
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Y. Fu, Z. Bo

Figure 1. Absorption and PL spectra (excited at 360 nm) of

polymers 5, 6, and 7 in solution (a) and in films (b).

were blue-shifted for about 20 nm. In comparison with the

3,6-linked carbazole polymers,[5] the absorption maxima of
polymer 6 and 7 were significantly red-shifted. These
results indicated that the introduction of alkyl chains
onto carbazole rings or the polymerization with 3,6-linked
monomers could decrease the effective conjugation length
of the polymers to some extent. The reason for the
introduction of alkyl chains onto carbazole rings decreasing
the effective conjugation length was that the alkyl chains on
carbazole rings could lead to larger dihedral angles between
the carbazole rings. The effective conjugation length of the
four polymers was in the following order: polymer
4 < polymer 6 < polymer 7 < polymer 5. In THF solution,
polymer 6 exhibited an emission band in the blue region
with one peak at 403 nm and one shoulder at 417 nm;
polymer 7 displayed an emission peak at 405 nm and a
shoulder at 425 nm. Compared with the emission spectra of
polymer 5 in THF solution, a blue shift of 1214 nm was
observed for the emission peaks of polymers 6 and 7. The
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fluorescence quantum efficient yields (FF) of the polymers

in toluene were measured with 9,10-diphenylanthracene as
a reference standard (toluene, FF 0.9, excited at 360 nm)
and are summarized in Table 1. In dilute toluene solution,
polymer 7 exhibited a very high fluorescence quantum
yield.
Solid films on quartz plates used for the optical
measurements were prepared by spin-coating with 1%
THF solution. Figure 1(b) shows the film absorption and
photoluminescence spectra of polymers 57. In contrast to
its solution spectrum, the absorption band of polymer 5 was
apparently broader and a long wavelength tail appeared. For
polymers 6 and 7, only slightly broadening and red shift
were observed for their film absorption spectra. The
broadening and red shift of the film absorption spectra
indicated that there existed some aggregations or interactions of the polymer chains in the solid state. Compared
with the solution emission spectra of polymers 57, a red
shift was observed in their film ones. In film polymer 5
displayed structural emission spectra with two peaks at 434
and 462 nm and a shoulder at around 492 nm. Polymers 6
and 7 displayed structureless emission spectra peaked at
414 and 418 nm, respectively. Compared with their solution
emission spectra, the emission maxima of polymers 6 and 7
were red-shifted for about 12 nm. Polymers 6 and 7
exhibited good thermal stability; no long-wavelength green
emission band was observed after their films (prepared by
spin-coating from toluene solution) were annealed at
120 8C in air for 5 h. In contrast, previous reports showed
that the annealing of polyfluorene film resulted in the
appearance of an additional emission band between 500 and
600 nm due to the formation of the ketonic defects. These
carbazole polymers showed promising results as blue lightemitting materials.
The electrochemical behaviors of polymers 6 and 7 were
investigated by using CV with a standard three-electrode
electrochemical cell in acetonitrile solution containing
0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6)
at room temperature. The oxidation potentials were measured versus Ag/AgNO3 as a reference electrode and a standard
ferrocene/ferrocenium redox system as the internal standard for estimating the HOMO of the polymer films. The
polymer films on the work electrodes were deposited by
casting from chloroform solution. The CV curves of
polymers 6 and 7 in film are shown in Figure 2 and 3,
respectively. In the range of 01.2 V, the film of polymer 6
displayed one oxidation peak at 0.76 V in the first redox
cycle. From the second redox cycle, the oxidation peak
shifted to a higher potential (0.89 V). The film exhibited
color and solubility changes accompanying the redox
process. The fresh yellow film became dark green and
insoluble in THF by increasing the applied potential up to
0.8 V. For polymer 7, the film showed one oxidation peak at
0.86 V in the first redox cycle and no peak in the successive
cycles in the range of 01.3 V. Similar to polymer 6, the
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Synthesis, Optical, and Electrochemical Properties of the High-Molecular-Weight Conjugated Polycarbazoles

The LUMO levels of polymers 6 and 7 in film were

estimated to be 2.43 and 2.57 eV, respectively.
In conclusion, we have successfully synthesized two
kinds of novel carbazole polymers by using palladiumcatalyzed SPC. Through the introduction of flexible alkyl
chains onto carbazole rings, we have obtained in high yield
soluble 2,7-linked carbazole polymers and boosted their
number-average molecular weight to 67 kDa. Through the
polymerization of 2,7-linked carbazole monomers with 3,6linked monomers, we have obtained soluble carbazole
polymers with a number-average molecular weight of 14.9
kDa. Primary studies indicated that 2,7-linked carbazole
polymers bearing alkyl chains were good blue lightemitting materials, which were of high PL quantum yield
(FF) and good thermal stability.
Figure 2. The first, second, and third redox cycles of polymer
6 film, measured at a scan rate of 0.1 V  s1 versus Ag/Ag in
acetonitrile with TBAPF6 as supporting electrolyte.

yellow film of polymer 7 also turned dark green and

insoluble in THF by increasing the potential applied up to
1.1 V. The unstability of polymers 6 and 7 was probably due
to that the 3,6-positions of the carbazole ring in 2,7-linked
carbazole polymers were highly activated and could form
the radical-cations of carbazolic units.[2022] The carbazole
polymers formed cross-linking structures during the CV
measurements.[23] Taking 4.8 eV as the HOMO level for
the ferrocene/ferrocenium redox system, HOMO level of
5.33 and 5.47 eV were calculated for polymers 6 and 7,
respectively. The band gap (DE) of 6 and 7 calculated from
the UV-vis absorption onset of the films were both 2.9 eV.

Figure 3. The first and second redox cycles of polymer 7 film,

measured at a scan rate of 0.1 V  s1 versus Ag/Ag in acetonitrile
with TBAPF6 as supporting electrolyte.
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Acknowledgements: Financial support from the National

Natural Science Foundation of China (No. 20225415, 20423003,
and 20374053), and the Major State Basic Research Development
Program (No. 2002CB613401) is greatly acknowledged.

[1] A. P. Kulkarni, C. J. Tonzola, A. Babel, S. A. Jenekhe, Chem.

Mater. 2004, 16, 4556.
[2] M. M. Alam, S. A. Jenekhe, Chem. Mater. 2004, 16, 4647.
[3] D. T. McQuade, A. E. Pullen, T. M. Swager, Chem. Rev.
2000, 100, 2537.
[4] [4a] J. Hwang, J. Sohn, S. Y. Park, Macromolecules 2003, 36,
7970; [4b] Y. Zhang, T. Wada, L. Wang, H. Sasabe, Chem.
Mater. 1997, 9, 2798; [4c] Y. Zhang, L. Wang, T. Wada, H.
Sasabe, Macromolecules 1996, 29, 1569; [4d] J. F. Morin,
M. Leclerc, D. Ade`s, A. Siove, Macromol. Rapid Commun.
2005, 26, 761.
[5] J. V. Grazulevicius, P. Strohriegl, J. Pielichowski, K.
Pielichowski, Prog. Polym. Sci. 2003, 28, 1297.
[6] [6a] K. R. J. Thomas, J. T. Lin, Y.-T. Tao, C.-W. Ko,
J. Am. Chem. Soc. 2001, 123, 9404; [6b] J. Li, D. Liu, Y. Li,
C.-S. Lee, H.-L. Kwong, S. Lee, Chem. Mater. 2005, 17,
1208.
[7] J. F. Morin, M. Leclerc, Macromolecules 2002, 35, 8413.
[8] [8a] K. Brunner, A. V. Dijken, H. Borner, J. J. A. M.
Bastiaansen, N. M. M. Kiggen, B. M. W. Langeveld, J. Am.
Chem. Soc. 2004, 126, 6035; [8b] A. V. Dijken, J. J. A. M.
Bastiaansen, N. M. M. Kiggen, B. M. W. Langevild, C. R.
Rothe, A. Monkman, I. Bach, P. Stossel, K. Brunner, J. Am.
Chem. Soc. 2004, 126, 7718.
[9] [9a] A. Siove, D. Ade`s, Polymer 2004, 45, 4045; [9b] A.
Iraqi, I. Wataru, Synth. Met. 2001, 119, 159.
[10] J. Ostrauskaite, P. Strohriegl, Macromol. Chem. Phys. 2003,
204, 1713.
[11] Y. Li, J. Ding, M. Day, Y. Tao, J. Lu, M. Diorio, Chem.
Mater. 2004, 16, 2165.
[12] Z. B. Zhang, M. Fujiki, H. Z. Tang, M. Motonaga, K.
Torimitsu, Macromolecules 2002, 35, 1988.
[13] J. F. Morin, M. Leclerc, Macromolecules 2001, 34, 4680.
[14] A. K. Flatt, Y. X. Yao, F. Maya, J. M. Tour, J. Org. Chem.
2004, 69, 1752.
2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

1709

1710

Y. Fu, Z. Bo

[15] M. Rehahn, A. D. Schluter, G. Wegner, W. J. Feast, Polymer

1989, 30, 1060.
[16] G. Zotti, G. Schiavon, S. Zecchin, J. F. Morin, M. Leclerc,
Macromolecules 2002, 35, 2122.
[17] J. Huang, Y. H. Niu, W. Yang, Y. Q. Mo, M. Yuan, Y. Cao,
Macromolecules 2002, 35, 6080.
[18] J. Bouchard, M. Belletete, G. Durocher, M. Leclerc,
Macromolecules 2003, 36, 4624.

Macromol. Rapid Commun. 2005, 26, 17041710

www.mrc-journal.de

[19] G. Wegner, Thin Solid films 1992, 216, 105.

[20] J. F. Ambrose, L. L. Carpenter, R. F. Nelson, J. Electrochem.
Soc. Electrochem. Sci. Techn. 1975, 122, 876.
[21] A. Siove, D. Ade`s, E. Ngbilo, C. Chevrot, Synth. Met. 1990,
38, 331.
[22] M. Sonntag, P. Strohriegl, Chem. Mater. 2004, 16, 4736.
[23] C. Xia, R. C. Advincula, Chem. Mater. 2001, 13,
1682.

2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim