Novel blue-light-emitting truxene-containing hyperbranched and zigzag type copolymers: Synthesis, optical properties, and investigation of thermal spectral stability

Article abstract of DOI:10.1021/ma048676s

Two series of novel alternating polyfluorene copolymers containing 10,15-dihydro-5-H-diindeno[1,2-α;1′,2′-c]fluorene (truxene) moiety have been prepared through the Pd(0)-catalyzed Suzuki polymerization. The structure and purity of desired polymers is ful

Full text of DOI:10.1021/ma048676s

8874
Macromolecules 2004, 37, 8874-8882
Novel Blue-Light-Emitting Truxene-Containing Hyperbranched and
Zigzag Type Copolymers: Synthesis, Optical Properties, and
Investigation of Thermal Spectral Stability
Xiao-Yu Cao, Xing-Hua Zhou, Hong Zi, and Jian Pei*
The Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education,
College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China
Received July 1, 2004; Revised Manuscript Received September 14, 2004
ABSTRACT: Two series of novel alternating polyfluorene copolymers containing 10,15-dihydro-5H-
diindeno[1,2-R;1′,2′-c]fluorene (truxene) moiety have been prepared through the Pd(0)-catalyzed Suzuki
polymerization. The structure and purity of desired polymers is fully characterized by 1H and 13C NMR,
UV-vis, and photoluminescent spectroscopy, gel permeation chromatography, elemental analyses, and
TGA/DSC. The absorption and PL spectra of all polymers both in solutions and in thin films exhibit
similar behaviors. For example, in solutions, the absorption spectra peak at about 360 nm, and the PL
spectra show a maximum at about 390 nm with a shoulder at 412 nm. The introducing of the truxene
moiety into polyfluorene and the hyperbranched and zigzag type molecular structures significantly reduce
aggregation formation and enhance the thermal spectral stability of the desired polymers. They exhibit
good solubility in common organic solvents as well as facile film forming properties. Bright blue emission
is observed in both solution and solid states under UV excitation. The investigation of thermal spectral
stability reveals that the long-wavelength emission upon thermal treatment usually observed in
polyfluorene has been effectively reduced in our polymers.
Introduction
dimensional (3D) structure.4j,k To provide further in-
sights into the effect of architectures and topologies on
polymer properties, we design two novel series of
polyfluorene copolymers containing the truxene moiety
with either zigzag type (P1 and P2) or hyperbranched
skeleton (P3 and P4) (Figure 1).
Tremendous progress has been made in the develop-
ment of organic light-emitting diodes (OLEDs) employ-
ing polymers as well as oligomers for their applications
in large-area light sources and flexible color displays
in the past few decades.1 OLEDs offer many incompa-
rable advantages, such as good processability, low
driving voltage, light weight, fast response, and the
possibility of producing displays on flexible substrates.2
Highly efficient and stable light emitters with three
primary colors (red, green, and blue) are prime criteria
for the realization of full color displays. Although all
three colors have been demonstrated in OLEDs,2b only
red (orange) and green emissions have sufficient ef-
ficiencies and lifetimes to be of commercial value.3 Thus,
substantial demands for blue light-emitting materials
with long-term stability and good color purity still exist.
π-Conjugated organic materials with large band gaps,
such as polyfluorenes, ladder-poly-p-phenylenes
(LPPP)s, and oligofluorenes, are generally regarded as
blue-light emitters.2,4 However, a prime problem associ-
ated with these materials concerns their tendency to
form long-wavelength π-aggregates/excimers or ketonic
defect sites in solid states during either annealing or
passage of current, resulting in poor color purity and
hence inhibiting their prospective utilization.4c,5
Truxene has been widely investigated for extensive
use as a starting material for the construction of larger
polyarenes and bowl-shaped fragment of the fullerenes,
liquid crystals, and C3 tripod materials in asymmetric
catalysis and chiral recognition.7,8 Few research works
on the synthesis and investigation of optical properties
of π-conjugated materials based on this heptacyclic
polyarene have been reported.9 The truxene moiety, by
virtue of its unique three-dimensional topology, is an
attractive building motif for use as potential dendrimer
building block via readily available functionalization at
C-2, C-7, and C-12 positions and C-5, C-10, and C-15
positions, respectively.9a Meanwhile, since the power of
copolymerization with suitable polyarene derivatives
such as anthracene has been demonstrated,6c,10 the
introduction of the truxene moiety into the polymer
backbone might offer some unique properties and
substantial improvement. Together with the meta-
linkage and intrinsic disordered 3D topology, the close
face-to-face π-stacking and other interchromophore
interactions in solid states are expected to effectively
release blue light.
In this paper, we report on the design, synthesis, and
characterization of two series of novel alternating poly-
fluorene copolymers (hyperbranched and zigzag types)
containing the truxene moiety (Figure 1). The methyl-
ene bridges in both the C-9 position of the fluorene
moiety and the C-5, C-10, and C-15 ones of the truxene
moiety have been modified with hexyl substituents in
order to improve the solubility of the desired polymers
as well as to minimize interchain interactions and thus
to achieve high photoluminescence (PL) quantum ef-
The general strategies to suppress the red-shifted and
less efficient emission are either introduction of bulky
side chains, copolymerization with suitable monomers,
attachment of sterically demanding end groups, or
appending aryl groups onto methylenes.4d,h,6 Most of the
intensively investigated blue light-emitting materials
are linear rigid-rod molecules together with a few
exceptions of spiro-linked examples processing a three-
* Corresponding author. E-mail: jianpei@chem.pku.edu.cn. Tele-
phone: 86-10-62758145. Fax: 86-10-62758145.
10.1021/ma048676s CCC: $27.50 © 2004 American Chemical Society
Published on Web 10/27/2004

Macromolecules, Vol. 37, No. 24, 2004
Novel Blue-Light-Emitting Copolymers 8875
Figure 1. Structures of polymers P1-P4.
ficiencies. For the syntheses of P1 and P2, one branch
of the three-dimensional truxene moiety has been
blocked by an aryl group, and the meta-linkage in these
molecules furnished zigzag copolymers by copolymeri-
zation with M5 in 1:1 molar ration via a Pd(0)-mediated
Suzuki coupling reaction. The hyperbranched P3 and
P4 were obtained by an “A2 + B3” approach. The
systematic investigation of their thermal spectral stabil-
ity indicates that the commonly observed red-shifted
and less efficient emission in polyfluorenes is efficiently
suppressed in our polymers, which makes them good
candidates as organic materials for blue-light emitting
devices.
presence of a mixture of toluene and aqueous Na2CO3
(2 M) with catalytic amounts (3 mol %) of Pd(PPh3)4
under nitrogen atmosphere. P1 and P2 exhibited the
zigzag figure (Figure 1), in which the meta-linkage was
introduced by the truxene moiety. Hyperbranched P3,
however, was synthesized via an “A2 + B3” approach.
The more reactive triiodide M3a resulted in higher
molecular weight and better yield compared to its
tribromide counterpart. P4, in which the terfluorene
segments were connected via benzenes by a meta-
linkage, was also prepared according to the same
procedure. The crude polymers were washed with
methanol, water, and methanol again, successively, and
then were placed in a Soxhlet apparatus and extracted
with acetone for 48 h.
Results and Discussion
All polymers are readily soluble in common organic
solvents, such as THF, toluene, chlorobenzene, xylene,
etc. The molecular structure of the polymers was
verified by 1H and 13C NMR spectroscopy and elemental
analysis. The molecular weights of alternating polymers
P1-P4 were determined by gel permeation chromatog-
raphy (GPC) with THF as the eluent, calibrated against
polystyrene standards. As shown in Table 1, the GPC
analysis indicated that the number-average molecular
weight (Mn) and polydispersity index of the polymers
are in the ranges (1.0-13.0) × 104 and 1.12-2.04,
respectively.
Thermal Stability. The thermal stabilities of P1-
P4 were investigated under nitrogen atmosphere by
thermogravimetric analysis (TGA), with the results
presented in Table 1. All polymers exhibited outstand-
ing thermal stability with onset degradation tempera-
tures (Td) above 400 °C. The average Td of our polymers
up to 400 °C is similar to that of poly(9,9-dihexylfluo-
rene-2,7-diyl) (PDHF) (ca. 400 °C), suggesting that both
the incorporation of truxene moiety and the unique
molecular structure (hyperbranched or zigzag) did not
affect the thermal stability. The thermally induced
Synthesis and Characterization. The synthetic
route is sketched in Schemes 1 and 2. Fully alkylation
has been done by introducing hexahexyl groups on the
C-5, C-10 and C-15 positions of readily available truxene
afforded Tr(Hex)6 with substantially enhanced solubil-
ity. Both the subsequent iodination and bromination
proceeded smoothly and afforded the corresponding
triiodide M3a and tribromide M3b with excellent yields
(90% and 93%, respectively). 4-Methylbenzylboronic acid
and 4-methoxybenzylboronic acid were employed to
block one branch of the three-dimensional truxene
moiety via the Suzuki coupling reaction, during which
the boronic acid and the tribromide M3b were in a 1:2
molar ratio. The relatively low yields of M1 and M2
could be attributed to the high reactivity of the boronic
acid, which lowered the selectivity and thus produced
amounts of di- and trisubstituted byproducts. When one
starts from 9,9-dihexyl-2-acetylfluorene, SiCl4 promoted
cyclotrimerization and subsequent alumina-supported
CuBr2 bromination afforded the M4 selectively and
efficiently.10 The polymerization of dibromide M1 and
M2 with diboronate M5 was carried out with standard
Suzuki cross-coupling at a feeding ratio of 1:1, in the

8876 Cao et al.
Macromolecules, Vol. 37, No. 24, 2004
Scheme 1. Synthesis of Monomers M1-M4
Table 2. UV-Vis Absorption and PL Emission Spectral
Scheme 2. Synthesis of Polymers P1-P4
Data of the Polymers in THF and as Films
solution λmax (nm)
film λmax (nm)
polymers
absorption
emission
absorption
emission
P1
P2
P3
P4
361
360
355
360
390, 413
392, 412
390, 412
394, 415
354
355
358
355
396, 415
416
410, 412
398, 419
However, neither the glass transition process (Tg) nor
other thermal processes (such as the liquid-crystal
phase) which significantly suppressed the mobility of
the polymer chain were observed from 20 to 300 °C,
indicating the amorphous nature and high branching
degree of the polymers.
Optical Properties. The optical properties of the
polymers were investigated both in solution and in the
solid state. The absorption and emission spectral data
are summarized in Table 2. P1, P2, and P4 showed
almost the same absorption spectra in diluted THF
solutions, so Figure 2 illustrates only the absorption
spectra of P4. The absorption maximum (λmax) peaked
at about 360 nm, due to a π-π* transition contributed
from the conjugated polymer backbone. In comparison
Table 1. Physical Properties of the Polymers
polymers
Mn
Mw
PD
Td (°C)
P1
9600
11000
10580
9200
16300
17600
118800
18900
15200
1.70
1.60
1.12
2.04
1.18
417
418
421
404
428
P2
P3a
P3b
P4
129500
phase transition behaviors of the polymers were deter-
mined by differential scanning calorimetry (DSC) under
nitrogen atmosphere at a heating rate of 10 °C min-1
.

Macromolecules, Vol. 37, No. 24, 2004
Novel Blue-Light-Emitting Copolymers 8877
Figure 2. UV-visible and photoluminescence spectra of P1-P4 in THF solutions at room temperature. P1, P2, P3, and P4
exhibit the similar absorption and emission behaviors.
Figure 3. UV-visible and photoluminescence spectra of P1-P4 in film states at room temperature. P1, P2, and P4 exhibit the
similar absorption spectra, and P1, P2, and P3 also have similar emission behaviors.
with absorption λmax of the truxene moiety (ca. 310
nm),8a the effective conjugation length in these polymers
increased substantially. For P3, we also observed that
the absorption maximum slightly blue-shifted 5 nm to
355 nm. Because of the introduction of the meta-linkage
truxene moiety (P1-P3) or hyperbranched nature (P4),
which reduced the conjugative interaction of the poly-
mer backbone and then their effective conjugation
length, the PL spectra of our polymers were blue shifted
in comparison with polyfluorene (PF) derivatives. All
polymers displayed the well-defined vibronic structure
in PL spectra. The truxene-functionalized polymers
(P1-P3) exhibited the peak at about 390 nm, with a
sharp band at ca. 412 nm and a shoulder at ca. 440 nm,
while slightly red-shift (ca. 5-10 nm) was observed in
those of the hyperbranched polymer P4 at ca. 394, 415,
and 450 nm, respectively. This is attributed to the
increase of polymer chain planarity and effective con-
jugation length upon more release of steric hindrance.
Uniform colorless polymer films were prepared on a
quartz glass substrate by spin-coating from solution in
toluene or THF (2% w/V) at a spin rate of 2000 rpm.
The thickness of all films was about 80-100 nm. All
polymers exhibited the very similar absorption behav-
iors in solid states. The UV-vis absorption maxima of
the polymers in thin films appeared at ca. 354 nm,
which were slightly blue-shifted from their values in
solutions, suggesting that there was little aggregation
of the chromophores in solid states. However, the PL
spectra of the polymers behaved differently when came
from solution to films. The peaks of the zigzag polymers
P1 and P2 did not show much bathochromic shift, but
the shoulder peak at ca. 415 nm increased substantially,
the intensity of the peak at ca. 396 nm decreased
significantly, even disappeared when the solution em-
ployed in spin-coating was changed from THF to tolu-
ene. The shoulder peak at ca. 445 nm did not exhibit
much change in intensity. The PL spectra of a hyper-
branched truxene-fluorene copolymer P3 film did not
exhibit any change in both the peak position and
intensity with respect to those in solutions but only
showed less definition of the vibronic structure. By
contrast, for P4, it was obvious that the emission
spectrum in thin films was much more red-shifted and
broader than those of the solution state, with its two
emission peaks moving from ca. 394 and 415 nm to ca.
398 and 419 nm, respectively, the shoulder peak of
which also increased significantly. It is clear that the
intermolecular interactions between neighboring mol-
ecules in thin films of P4 were larger than those of
truxene-containing polymers. It is also indicative that
the incorporating of both the meta-linkage giant truxene
moiety and hyperbranched structure is effective to
depress the aggregation formation in the solid state.
Thermal Spectral Stability. The color and lumi-
nescence stability upon annealing temperatures are
critical characters for OLEDs, since the temperature
inside the devices could increase depending on the
operation conditions. It is well-known that when PF
films were heated with exposure to air, an additional
broad, featureless band emerged and increased, result-
ing in a decreased efficiency as well as changing the
pure blue emission to an undesirable blue-green color.12
To examine the thermal stability of our polymers, we

8878 Cao et al.
Macromolecules, Vol. 37, No. 24, 2004
Figure 4. PL emission spectra of P1, P2, P3a, P3b, P4, and PDHF films after thermal annealing at different temperatures and
time under air: (a) 100 °C for 3 h; (b) 150 °C for 3 h; (c) 200 °C for 0.5 h; (d) 200 °C for 3 h. During thermal annealing, P1 exhibits
the same behavior as P2.
thermally treated the spin-coated polymer films in
different manners and then systematically studied their
spectra. The commonly reported PDHF (polydihexyl-
fuluorene) was employed in our experiment for com-
parison.
To better elucidate the interesting thermal spectral
behaviors of our polymers, we presented PL spectra in
solid states of each polymer before and after thermal
annealing at various conditions separately in Figure 5.
The tendencies of the PL spectra upon annealing were
quite similar for P1 and P2, since both of them
contained the zigzag molecular structure as well as
moderate molecular weight. P3a exhibited excellent
stability; its PL spectrum did not show any measurable
spectral change after the annealing either at 150 °C for
3 h or at 200 °C for 30 min. The additional emission
band was only characterized as a shoulder after we
heated the film at 200 °C for 3 h. In contrast, this band
increased steadily with elevated temperatures and
prolonged time and became pronounced upon annealing
at 200 °C for 3 h. The dependency of aggregation
tendency on the molecular weight distribution in linear
fluorene homopolymers indicated that a higher molec-
ular weight polymer would possess a lower average
chain mobility due to the ability of random coil forma-
tion.13 So it is reasonable to understand our observations
in this manner despite of that our polymers were
hyperbranched alternating copolymers. Meantime, the
large amount of terminal functional groups in P3b also
resulted in decreased thermal stability. Hyperbranched
P4 also exhibited outstanding stability; its PL spectrum
remained unchanged even after thermal annealing at
200 °C for 3 h, which was similar to the behavior of
another hyperbranched polymer.14 Incorporating the
novel truxene moiety substantially improved the emis-
sion spectral quality in terms of both narrower spectrum
and better thermal stability.
Figure 4 presented the normalized PL emission
spectra of our polymers and PDHF films at 100, 150,
200, and 200 °C for 3, 3, 0.5, and 3 h, respectively.
Thermal treatment of the PDHF film at 100 °C for 3 h
led to a significant increase of the shoulder peak at ca.
460 nm, while the PL spectra of our polymers remained
largely intact. With the temperature increased, the
additional long wavelength emission at ca. 520 nm
became apparent for PDHF, while it was only observed
as an insignificant shoulder in PL spectra of P1, P2,
and P3b. Any effects were observed on PL spectra of
hyperbranched polymer films (P3a and P4) under this
condition, indicating that the hyperbranched molecular
structure could effectively hamper the aggregation
formation of the polymer backbones. The long wave-
length emission was further increased for PDHF in
Figure 4c, wherein the polymer films were heated to 200
°C for 30 min, but the spectra of our polymers were
similar to that in Figure 4b, indicating that an enhanced
resistance to the aggregation or keto defect formation
in comparison with PDHF exists. When the annealing
time was extended to 3 h, a strong green emission at
ca. 520 nm dominated in the spectrum of PDHF, those
of P3b showed a lower intensity, and those of P1 and
P2 were even lower. For the case of P3a and P4, the
intensity was significantly reduced. We observed that
P1 exhibited the same color stability as P2 due to their
almost identical structures.

Macromolecules, Vol. 37, No. 24, 2004
Novel Blue-Light-Emitting Copolymers 8879
Figure 5. PL emission spectra of polymer films before and after thermal annealing under air: (a) P1; (b) P2; (c) P3a; (d) P3b;
(e) P4.
Conclusion
Experimental Section
General Data. Chemicals were purchased from Aldrich,
Acros, and Lancaster and used as received. Compounds 10,15-
dihydro-5H-diindeno[1,2-R;1′,2′-c]fluorene (truxene),7c M4,10
and M55f were synthesized according to literature procedures.
1H and 13C NMR spectra were recorded on a Varian Mercury
200 MHz, Mercury plus 300 MHz, or Bruker 400 MHz using
CDCl3 or CD2Cl2 as solovent in all cases. Elemental analyses
were carried out on an Elementar Vario EL (Germany). UV-
vis spectra were recorded on a Perkin-Elmer Lambda 35 UV-
vis spectrometer. PL spectra were carried out on Perkin-Elmer
LS 55B Luminescence spectrometer.
General Instrumentation and Conditions for
MALDI)TOF MS Spectra. MALDI/TOF (matrix assisted
laser desorption ionization/time-of-flight) MS spectra were
recorded in Bruker BIFLEX III. MALDI experiments were
carried out using a Bruker BIFLEX III time-of-flight (TOF)
mass spectrometer (Bruker Daltonics, Billerica, MA). The
instrument was equipped with a N2 laser emitting at 337 nm
(Laser Sciences Inc., Cambridge, MA), a 1-GHz sampling rate
We have synthesized two series of novel conjugated
polymers composed of fluorene and truxene units, via
the palladium-catalyzed Suzuki coupling reaction. This
represents the first synthesis of truxene-containing
polymers, which exhibit unique hyperbranched and
zigzag type molecular structures. The derived polymers
give strong blue both in solutions and in film states. The
results from the PL measurements of the annealed films
at different temperature and time in the air indicate
that the long wavelength emission was significantly
reduced and thermal spectral stability was enhanced
in our polymers. Hence, we provide a novel approach
for preparing blue OLED materials with improved
thermal and optoelectronic properties by incorporation
of the truxene moiety into the polyfluorene backbones.
The performance of single layer OLED devices will be
reported elsewhere.

8880 Cao et al.
Macromolecules, Vol. 37, No. 24, 2004
digitizer, a pulsed ion extraction source, and an electrostatic
reflectron. The laser pulse width was 3 ns, and its maximum
power was 200 µJ. Spectra were acquired in the positive-ion
mode using the reflectron. The acceleration voltage was 19 kV.
The delay voltage was 14.3 kV, the delay time was 200 ns,
and the reflectron voltage was 20 kV. Typically, 100 single-
shot mass spectra were summed to give a composite spectrum.
All data were reprocessed using the Bruker XTOF software.
The mass scale was calibrated externally, using the peptides
angiotensin II, bovine insulin b-chain, bovine insulin, and
equine cytochrome C (Sigma, St. Louis, MO) as mass stan-
dards. EI spectral data were obtained using a double-focusing
mass spectrometer (ZAB-HS, Micromass, Manchester, U.K.)
coupled with a MASPEC II data system. The resolving power
(10% valley definition) was typically 1000, and the magnet was
scanned at 3 s per decade.
residue, which was then combined with the white precipitate.
Recrystallization of the combined solid from EtOH afforded
pure M3b (11.91 g, 93%) as a white solid. 1H NMR (CDCl3,
400 MHz, ppm, δ): 8.15-8.26 (3H, d, J ) 8.5 Hz, Tr-H), 7.57-
7.65 (3H, s, Tr-H), 7.50-7.57 (3H, d, J ) 8.5 Hz, Tr-H), 2.78-
2.96 (6H, m, CH2), 1.96-2.13 (6H, m, CH2), 0.79-1.03 (36H,
m, CH2), 0.60-0.70 (18H, t, J ) 7.2 Hz, CH3), 0.38-0.57 (12H,
m, CH2). 13C NMR (CDCl3, 100 MHz, ppm, δ): 156.28, 145.31,
139.26, 138.06, 129.77, 126.29, 125.94, 121.44, 56.39, 37.22,
31.82, 29.74, 24.27, 22.62, 14.21.
M1. To a degassed mixture of Pd(PPh3)4 (100 mg, 0.09 mmol)
and compound M3b (10.00 g, 9.22 mmol) in 90 mL of THF
were added 4-methylbenzylboronic acid (0.627 g, 4.61 mmol)
and 60 mL of 2 M Na2CO3 aqueous solution. The mixture was
refluxed overnight, poured into a saturated solution of am-
monium chloride, and extracted with ethyl acetate three times.
The combined extracts were washed with brine and dried over
MgSO4. After the solvent was removed by rotary evaporation,
the remaining oil was purified by flash chromatography using
petroleum ether as eluent to give M1 (1.21 g, 24%) as a light
Reagents. MALDI analysis of the polymers utilized Dithra-
nol (DI) purchased from Aldrich (Milwaukee, WI). Inhibitorfree
tetrahydrofunan and anhydrous methanol were purchased
from Aldrich (Milwaukee, WI). LiCl, NaCl, KCl, RbCl, CsCl,
AgTFA, and trifluoroacetic acid (TFA) were purchased from
Acros (Fairlawn, NJ).
1
yellow solid. H NMR (CDCl3, 300 MHz, ppm, δ): 8.32-8.38
(1H, d, J ) 8.4 Hz, Tr-H), 8.21-8.26 (1H, d, J ) 8.7 Hz, Tr-
H), 8.15-8.21 (1H, d, J ) 8.1 Hz, Tr-H), 7.60-7.69 (4H, m,
Ar-H), 7.55-7.60 (2H, dd, J ) 4.8 Hz, J ) 1.8 Hz, Tr-H),
7.47-7.54 (2H, td, J ) 6.3 Hz, J ) 2.1 Hz, Tr-H), 7.28-7.36
(2H, d, J ) 7.8 Hz, Ph-H), 2.80-3.08 (6H, m, CH2), 2.44-
2.46 (3H, s, Ph-CH3), 1.96-2.18 (6H, m, CH2), 0.74-1.02
(36H, m, CH2), 0.56-0.67 (18H, m, CH3), 0.42-0.56 (12H, m,
CH2). 13C NMR (CDCl3, 100 MHz, ppm, δ):156.08, 155.93,
154.11, 144.36, 139.41, 139.21, 139.13, 138.83, 138.35, 137.11,
129.58, 129.30, 129.27, 126.96, 126.00, 125.55, 125.06, 124.84,
120.87, 120.85, 120.49, 56.07, 55.95, 55.80, 37.06, 36.91, 36.84,
31.47, 31.44, 29.46, 29.41, 23.94, 23.91, 23.90, 22.29, 22.27,
22.21, 21.17, 13.88, 13.85. MALDI/TOF MS: calcd for C70H94-
Br2, 1194.6; found, 1094.6 ([M]+, 100%).
Sample Preparation. The dendrimers, matrix, and AgTFA
were dissolved in THF with concentrations of 1.5 × 10-4 mol/
L, 10 g/L, and 1 × 10-2 mol/L, respectively. Alkali salts were
dissolved in a mixture solvent (CH3OH:H2O:TFA ) 2:1:0.03)
at 1 × 10-2 mol/L. The mixed sample solution was mixed at
the ratio of 1:3:1 (Vanalyte:Vmatrix:Vcation). We used the dried
droplet method to prepare sample target: 1 µL of sample
mixture was applied to the sample target and air-dried.
Tr(Hex)6. With vigorous stirring, 36.5 mL of n-BuLi (1.6
M, 10 equiv) was added to a suspension of truxene (2.00 g,
5.84 mmol) in 60 mL of anhydrous THF at -78 °C and the
mixture was kept at this temperature over a period of 2 h. A
solution of n-hexyl bromide (8.82 g, 10 equiv) in THF was then
added dropwisely. The reaction mixture was allowed to slowly
turn to room temperature and stirred overnight. The mixture
was then poured into 200 mL of saturated aqueous NaCl
solution with stirring for 15 min. The water phase was exacted
with ethyl acetate for twice, and then the combined organic
phase was dried over MgSO4. After the solvent was removed,
the residue was purified by flash column chromatography
using petroleum ether as eluent to afford Tr(Hex)6 (4.95 g,
100%) as a light yellow solid. 1H NMR (CDCl3, 300 MHz, ppm,
δ): 8.30-8.42 (3H, d, J ) 8.1 Hz, Tr-H), 7.45-7.49 (3H, m,
Tr-H), 7.31-7.43 (6H, m, Tr-H), 2.83-3.06 (6H, m, CH2),
1.96-2.18 (6H, m, CH2), 0.66-1.00 (36H, m, CH2), 0.54-0.61
(18H, m, CH3), 0.39-0.51 (12H, m, CH2). 13C NMR (CDCl3,
125 MHz, ppm, δ): 153.60, 144.82, 140.30, 138.28, 126.34,
125.87, 124.59, 122.13, 55.56, 36.89, 31.49, 29.54, 23.88, 22.34,
13.86.
M3a. A mixture of Tr(Hex)6 (5.00 g, 5.91 mmol) and 15 mL
of solvent (CH3COOH:H2SO4:H2O ) 100:40:3) was heated to
60 °C with vigorous stirring, followed by adding 3 mL of CHCl3,
KIO4 (1.15 g, 4.9 mmol), and I2 (2.50 g, 9.85 mmol). The
mixture was stirred at 80 °C under nitrogen atmosphere. After
the mixture was cooled to room temperature and 150 mL of
water was added, the brown precipitate was filtered and
purified by recrystallization three times from ethanol to afford
M3a (6.51 g, 90%) as a white solid. 1H NMR (CDCl3, 300 MHz,
ppm, δ): 7.92-8.14 (3H, d, J ) 12 Hz, Tr-H), 7.72-7.80 (3H,
s, Tr-H), 7.64-7.72 (3H, d, J ) 12 Hz, Tr-H), 2.72-2.98 (6H,
m, CH2), 1.88-2.16 (6H, m, CH2), 0.76-1.08 (36H, m, CH2),
0.59-0.76 (18H, t, J ) 9.0 Hz, CH3), 0.29-0.58 (12H, m, CH2).
13C NMR (CDCl3, 100 MHz, ppm, δ): 155.97, 145.00, 139.54,
137.63, 135.31, 131.53, 126.25, 92.62, 55.95, 36.77, 31.44,
29.37, 23.89, 22.27, 13.88.
M2. Compound M2 was prepared according to the procedure
described for M1 except that 4-methoxybenzylboronic acid
(0.701 g, 4.61 mmol) was used instead of 4-methylbenzyl-
boronic acid. The compound M2 (2.00 g, 39%) was afforded as
light yellow solids. 1H NMR (CDCl3, 300 MHz, ppm, δ): 8.30-
8.38 (1H, d, J ) 8.4 Hz, Tr-H), 8.21-8.35 (1H, d, J ) 8.7 Hz,
Tr-H), 8.15-8.21 (1H, d, J ) 8.7 Hz, Tr-H), 7.65-7.74 (2H,
d, J ) 8.7 Hz, Ph-H), 7.59-7.64 (2H, s, Tr-H), 7.56-7.60
(2H, dd, J ) 4.5 Hz, J ) 1.8 Hz, Tr-H), 7.48-7.55 (2H, td, J
) 4.5 Hz, J ) 8.4 Hz, J ) 1.8 Hz, Tr-H), 7.00-7.10 (2H, d, J
) 8.4 Hz, Ph-H), 3.80-3.94 (3H, s, OCH3), 2.74-3.06 (6H,
m, CH2), 1.90-2.21 (6H, m, CH2), 0.72-1.04 (36H, m, CH2),
0.54-0.68 (18H, m, CH3), 0.36-0.56 (12H, m, CH2). 13C NMR
(CDCl3, 100 MHz, ppm, δ): 159.25, 156.07, 155.93, 144.79,
139.21, 139.13, 139.07, 138.53, 138.43, 133.77, 129.29, 129.26,
128.12, 125.86, 125.54, 125.48, 124.85, 124.82, 120.85, 120.19,
114.33, 56.05, 55.93, 55.78, 55.43, 37.06, 36.91, 36.84, 31.47,
29.46, 29.44, 29.41, 23.94, 23.90, 22.29, 22.27, 22.25, 22.21,
13.87, 13.85. MALDI/TOF MS: calcd for C70H94Br2O, 1110.6;
found, 1110.6 ([M]+, 100%).
P1. To a 1:1 (molar ratio) mixture of M1 (1.00 g, 0.913
mmol), M5 (0.459 g, 0.913 mmol), and Pd(PPh3)4 (35 mg, 0.03
mmol) was added a degassed mixture of 4 mL of toluene and
2.7 mL of 2 M Na2CO3 aqueous solution. The mixture was
vigorously stirred at 90 °C for 48 h under the protection of
nitrogen. After the mixture was cooled to room temperature,
it was poured into a stirred mixture of methanol and deionized
water (10:1). A fibrous solid was obtained by filtration. The
solid was washed with methanol, water, and methanol, dis-
solved with THF, and dedoped with N2H4 aqueous solution.
The catalyst residues were filtered off, and the organic phase
was separated. Removal of the solvents gave a white residue,
which was further purified by washing with acetone in a
Soxhlet apparatus for 48 h to remove oligomers and was dried
under reduced pressure at room temperature to afford the P1
(0.62 g, 53%) as a white solid. 1H NMR (CDCl3, 400 MHz, ppm,
δ): 8.16-8.24 (3H, m, Tr-H), 7.86-7.93 (2H, d, J ) 7.8 Hz,
Ph-H), 7.76-7.83 (8H, m, Ar-H), 7.65-7.76 (5H, m, Ar-H),
7.54-7.62 (1H, m, Ar-H), 7.43-7.52 (1H, m, Ar-H), 7.32-
7.38 (2H, d, J ) 7.9 Hz, Ph-H), 2.92-3.13 (6H, m, CH2), 2.44-
M3b. To a mixture of Tr(Hex)6 (10.00 g, 11.81 mmol) and
20 mg of anhydrous FeCl3 as catalyst in 60 mL of chloroform
was added dropwise a solution of bromine (2.05 mL, 40.00
mmol) in 10 mL of chloroform at 0 °C over 1 h. After 24 h, the
mixture was washed with saturated sodium thiosulfate solu-
tion and brine to remove excess bromine. The precipitate was
filtered and washed with water three times. The organic phase
was washed with brine. Removal of the solvents gave a yellow

Macromolecules, Vol. 37, No. 24, 2004
Novel Blue-Light-Emitting Copolymers 8881
2.52 (3H, s, Ph-CH3), 2.05-2.16 (10H, m, CH2), 1.04-1.16
(14H, m, CH2), 0.88-1.09 (36H, m, CH2), 0.76-0.88 (8H, m,
CH2, CH3) 0.42-0.64 (30H, m, CH2, CH3). 13C NMR (CDCl3,
100 MHz, ppm, δ): 154.45, 151.83, 145.15, 140.15, 139.64,
139.47, 139.40, 138.50, 138.20, 138.09, 136.95, 129.55, 128.79,
127.20, 126.94, 126.10, 125.23, 124.95, 121.31, 120.50, 120.05,
55.84, 55.41, 40.58, 37.13, 31.56, 31.51, 31.39, 29.76, 29.60,
29.52, 24.03, 23.89, 22.61, 22.33, 21.17, 14.03, 13.92, 13.81.
Anal. Calcd for C95H126: C, 89.98; H, 10.02. Found: C, 89.34;
H, 9.93.
m, CH2, CH3). 13C NMR (CDCl3, 100 MHz, ppm, δ): 151.92,
151.79, 150.98, 143.00, 140.76, 140.69, 140.47, 140.10, 140.03,
139.93, 128.77, 127.19, 126.39, 126.18, 126.03, 121.84, 121.52,
121.43, 120.06, 119.99, 119.88, 119.71, 55.41, 55.33, 55.24,
55.15, 40.43, 31.46, 29.70, 23.85, 22.56, 14.01. Anal. Calcd for
C237H294: C, 90.57; H, 9.43. Found: C, 89.46; H, 9.21.
Acknowledgment. This work was supported by the
Major State Basic Research Development Program (No.
2002CB613401) from the Minister of Science and Tech-
nology, and by the National Natural Science Foundation
of China (NSFC. 90201021 and 50103001).
P2. P2 was prepared according to the procedure described
for P1 except that compound M2 (1.00 g, 0.900 mmol) was used
instead of compound M1. P2 (0.51 g, 44%) was afforded as a
white solid.1H NMR (CDCl3, 400 MHz, ppm, δ): 8.14-8.23
(3H, m, Tr-H), 7.90-7.94 (2H, d, J ) 7.7 Hz, Ph-H), 7.54-
7.80 (13H, m, Ar-H), 7.46-7.53 (1H, m, Ar-H), 6.96-7.03
(2H, d, J ) 8.4 Hz, Ph-H), 3.87-3.93 (3H, s, OCH3), 2.92-
3.16 (6H, m, CH2), 2.02-2.15 (10H, m, CH2), 1.06-1.12 (14H,
m, CH2), 0.88-1.09 (38H, m, CH2), 0.76-0.82 (9H, m, CH2,
CH3) 0.48-0.65 (30H, m, CH2, CH3). 13C NMR (CDCl3, 100
MHz, ppm, δ): 159.12, 154.43, 151.81, 145.08, 140.14, 139.63,
139.45, 139.08, 138.69, 138.20, 138.07, 133.93, 128.78, 128.10,
127.19, 126.06, 124.93, 121.29, 120.03, 114.27, 55.82, 55.78,
55.40, 40.56, 37.14, 31.55, 31.50, 31.38, 29.75, 29.59, 29.52,
29.33, 24.02, 23.88, 22.60, 22.32, 14.02, 13.91. Anal. Calcd for
C95H126O: C, 88.86; H, 9.89. Found: C, 88.49; H, 9.78.
P3a. To a 2:3 (molar ratio) mixture of M3a (1.23 g, 1.00
mmol), M5 (0.75 g, 1.50 mmol), and Pd(PPh3)4 (35 mg, 0.03
mmol) was added a degassed mixture of 4 mL of toluene and
2.7 mL of 2 M Na2CO3 aqueous solution. The mixture was
vigorously stirred at 90 °C for 48 h under the protection of
nitrogen. After the mixture was cooled to room temperature,
it was poured into a stirred mixture of methanol and deionized
water (10:1). A fibrous solid was obtained by filtration. The
solid was washed with methanol, water, and methanol, dis-
solved with THF, and dedoped with N2H4 aqueous solution.
The catalyst residues were filtered off, and the organic phase
was separated. Removal of the solvents gave a white residue,
which was further purified by washing with acetone in a
Soxhlet apparatus for 48 h to remove oligomers and was dried
under reduced pressure at room temperature to afford the P3a
(0.78 g, 59%) as a white solid. 1H NMR (CDCl3, 400 MHz, ppm,
δ): 8.18-8.24 (3H, m, Tr-H), 7.76-7.92 (16H, m, Ar-H),
7.58-7.64 (3H, m, Ar-H), 7.44-7.56 (4H, m, Ar-H), 7.38-
7.45 (1H, m, Ar-H), 2.90-3.11 (6H, m, CH2), 2.02-2.16 (12H,
m, CH2), 1.10-1.22 (20H, m, CH2), 0.87-1.09 (38H, m, CH2),
0.70-0.87 (16H, m, CH2, CH3) 0.44-0.66 (36H, m, CH2, CH3).
13C NMR (CDCl3, 100 MHz, ppm, δ): 140.25, 140.13, 140.08,
138.13, 132.25, 132.15, 131.96, 128.78, 128.55, 128.43, 127.55,
127.20, 126.06, 56.01, 55.85, 55.41, 40.51, 31.54, 31.48, 30.92,
29.72, 29.59, 29.52, 29.32, 24.04, 23.93, 23.86, 22.58, 22.32,
References and Notes
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13.99, 13.92. Anal. Calcd for C201H270
: C, 89.87; H, 10.13.
Found: C, 88.95; H, 9.93.
P3b. All the conditions and procedures were the same as
that in P3a except that the triiodo compound M3a (1.23 g,
1.00 mmol) was replaced by tribromide M3b (1.08 g, 1.00
mmol). The desired P3b (0.67 g, 51%) was obtained as a yellow
solid. 8.18-8.24 (3H, m, Tr-H), 8.11-8.21 (1H, m, Ar-H),
7.65-7.94 (11H, m, Ar-H), 7.48-7.62 (3H, m, Ar-H), 7.28-
7.43 (2H, m, Ar-H), 2.92-3.10 (6H, m, CH2), 2.02-2.42 (11H,
m, CH2), 1.19-1.30 (18H, m, CH2), 0.89-1.16 (38H, m, CH2),
0.70-0.87 (12H, m, CH2, CH3) 0.42-0.68 (32H, m, CH2, CH3).
13C NMR (CDCl3, 100 MHz, ppm, δ): 154.39, 151.82, 150.97,
140.15, 140.06, 139.63, 138.13, 128.78, 127.20, 126.09, 125.93,
124.92, 122.91, 121.28, 121.21, 120.51, 120.04, 119.93, 119.72,
56.03, 55.84, 55.40, 55.19, 40.47, 37.07, 36.96, 31.54, 31.49,
29.73, 29.57, 29.51, 23.97, 23.89, 23.78, 22.58, 22.32, 14.00,
13.91. Anal. Calcd for C201H270: C, 89.87; H, 10.13. Found: C,
88.53; H, 9.96.
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1
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