A fully aryl-substituted poly(ladder-type pentaphenylene): A remarkably stable blue-light-emitting polymer

Article abstract of DOI:10.1021/ma0517143

A new poly(ladder-type pentaphenylene) bearing aryl groups at all bridgehead positions has been prepared. In comparison to previously reported bridged poly(p-phenylene)-type polymers such as polyfluorene and polyindenofluorene, this polymer is optimized f

Full text of DOI:10.1021/ma0517143

Macromolecules 2005, 38, 9933-9938
9933
A Fully Aryl-Substituted Poly(ladder-type pentaphenylene): A
Remarkably Stable Blue-Light-Emitting Polymer
Josemon Jacob,† Stefan Sax,‡ Martin Gaal,‡ Emil J. W. List,‡
Andrew C. Grimsdale,†,§ and Klaus Mu1 llen*,†
Max-Planck-Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany, and
Christian Doppler Laboratory “Advanced Functional Materials”, Institute of Solid State Physics, Graz
University of Technology, Petersgasse 16, A-8010 Graz, Austria, and Institute of Nanostructured
Materials and Photonics, Joanneum Research, Franz-Pichler-Strasse 30, A-8160 Weiz, Austria
Received August 2, 2005; Revised Manuscript Received September 27, 2005
ABSTRACT: A new poly(ladder-type pentaphenylene) bearing aryl groups at all bridgehead positions
has been prepared. In comparison to previously reported bridged poly(p-phenylene)-type polymers such
as polyfluorene and polyindenofluorene, this polymer is optimized for maximum overlap of the blue
emission with the sensitivity of the human eye. Furthermore, the introduction of aryl substituents at all
the bridgeheads produces a material which shows remarkably stable blue emission in light-emitting diodes
and is not subject to oxidative degradation-induced defect formation. In particular, a comparison of the
novel fully aryl-substituted polymer with a partially aryl-substituted polymer reveals that the oxidative
degradation-induced defect formation can be almost completely eliminated upon aryl substitution.
Introduction
bridgeheads and to hindrance of exciton migration to
any defect sites that may arise. Although LEDs using
polymer 4 showed stable blue emission when operated
for several minutes at 6-7 V in a glovebox,10 further
testing revealed that the emission was not stable over
longer periods or upon operation outside a glovebox.
This we attribute to the susceptibility of the dialkyl
bridgeheads toward oxidation leading to the formation
of keto defects at the bridgeheads although extreme care
was taken in the synthesis to ensure complete alkyla-
tion.10 It has been previously reported that chemical
defects arising from partial alkylation at the bridge-
heads in ladder-type poly(phenylenes) can lead to keto
defects either during synthesis or device operation.6 It
soon became apparent that the synthesis of a fully
arylated polymer as in 5 can help eliminate or minimize
the possibility of partially substituted bridgeheads and
thereby improve stability of such materials. Toward
this, we now report on the synthesis of a fully arylated
poly(ladder-type pentaphenylene) 5 and the results of
device testing confirming that it produces much more
stable blue emission than 4.
Conjugated polymers are of considerable academic
and industrial importance as the active materials in the
emerging new technologies of organic light-emitting
diodes (OLEDs)1,2 and polymer lasers.3 The full realiza-
tion of these technologies will require the development
of materials that produce efficient, stable blue emission.4
Much research into blue-emitting polymers has centered
on p-phenylene-based materials such as poly(dialkyl-
fluorene)s (PFs, 1),5,6 poly(tetraalkylindenofluorene)s
(PIFs, 2),7,8 and ladder-type polyphenylenes (LPPPs, 3)
(Figure 1).9 All these materials suffer from problems
with color purity and color stability. The emission from
PFs and PIFs is blue-violet in color (emission maxima
λmax ) 420-430 nm), while LPPPs (λmax ) 450-470 nm)
produce blue-green emission, and so recently we intro-
duced a new type of blue-emitting polymer, poly(ladder-
type pentaphenylene) (4),10 which displays a purer blue
emission (λmax 443 nm) with a very small Stokes shift
and well-resolved vibrational bands. Devices were con-
structed which produced blue emission with moderate
efficiencies.
The second problem of color stability in polymers 1-3
manifests itself by the rapid appearance of long-
wavelength emission bands during operation of LEDs,5,8,9
which were initially attributed to aggregation of the
polymer chains.5,8,11 More recently, it has been shown
that the emission from PFs arises from the formation
of fluorenone defects,6,12 and similar ketone defects have
been proposed as the origins for the long-wavelength
band from PIFs13 and LPPPs.14 We have previously
shown that replacement of the bridgehead alkyl sub-
stituents with aryl groups in PFs15,16 and PIFs17 sup-
presses the long-wavelength emission due both to a
lower susceptibility toward oxidation of the arylated
Results and Discussion
Synthesis and Characterization. The synthetic
approach to the desired polymer 5 is outlined in Scheme
1. To prepare a fully arylated pentaphenylene, it was
necessary to first synthesize a 9,9-diarylfluorene-2-
boronate. Starting from commercially available re-
agents, 4′-trimethylsilylbiphenyl-2-carboxylic acid meth-
yl ester (6) was synthesized by a standard Suzuki-type
coupling reaction in 97% yield. Addition of 2 equiv of
aryllithium produced the corresponding alcohol, and
then exchange of the trimethylsilyl group with a bro-
mine atom followed by ring closure using BF3‚etherate
generated the diaryl-substituted monobromofluorene 7
(73%). The monobromide 7 was first converted to the
corresponding boronate ester 8 (78%), and then Suzuki
coupling with 2,5-dibromodimethyl terephthalate (9)
gave the pentaphenylene diester 10 in 91% yield. The
ladder-type pentaphenylene 11 was then synthesized in
† Max-Planck-Institute for Polymer Research.
‡ Graz University of Technology and Institute of Nanostructured
Materials and Photonics.
§ Current address: Bio21 Institute, University of Melbourne,
30 Flemington Road, Parkville 3010, Victoria, Australia.
* Corresponding author. E-mail: muellen@mpip-mainz.mpg.de.
10.1021/ma0517143 CCC: $30.25 © 2005 American Chemical Society
Published on Web 11/03/2005

9934 Jacob et al.
Macromolecules, Vol. 38, No. 24, 2005
Figure 1. Polyphenylene-based conjugated polymers.
Scheme 1. Synthesis of Polymer 5
92% yield by addition of 4 equiv of aryllithium to the
diester followed by ring closure using BF3‚etherate.
From this, the monomer 12 was obtained in nearly
quantitative yield by bromination using CuBr2 on
alumina or Br2 in CCl4. The polymer 5 was then
obtained (86%) by standard Yamamoto-type polycon-
densation using stoichiometric nickel(0) reagent.
GPC analysis using PPP standard showed a Mn value
of 2.80 × 104 with a polydispersity of 2.65. This
corresponds to a degree of polymerization of around 16,
and the all-aryl polymer 5 possesses excellent solubility
in solvents such as dichloromethane, chloroform, and
toluene and good film-forming abilities. Thermogravi-
metric analysis (TGA) showed the material to be stable
up to 350 °C, and DSC analysis showed no phase
transition in the temperature range from -50 to 300
°C (see Supporting Information for details).
Polymer 5 shows blue fluorescence in solution with
an emission maximum at 441 nm (Figure 2), which is
essentially identical to that of the aryl-alkyl polymer
4. In the film, the fluorescence shows a maximum at
λmax ) 444 nm. The absorption is also in the blue
spectral region with its maximum at 434 nm, resulting
in a very small Stokes shift of 7 nm, which is due to the
rigidity of polymer 5. A comparison of the film and
solution spectra reveals a small bathochromic shift of
the film spectra of ca. 6 nm as well as a moderate
broadening of the spectra in absorption and emission.
The broadening as well as the bathochromic shift is
typical for such polymers and can be attributed to the
formation of additional, more planar conformations of
the polymer in the solid state.6
To determine their overall stability against the for-
mation of oxidative keto-type defects yielding the un-

Macromolecules, Vol. 38, No. 24, 2005
Aryl-Substituted Poly(ladder-type pentaphenylene) 9935
Figure 2. Absorption (left) and photoluminescence (right) of
polymer 5 in film (circles) and solution (squares).
Figure 4. Normalized photoluminescence spectra of a spin-
coated polymer 5 film before and after annealing. Again, the
film was measured directly after preparation (filled squares),
stored in darkened atmosphere, and heated stepwise. Filled
cycles: after 1 h at 100 °C; open triangles: 1 h at 133 °C; filled
triangles: 1 h at 166 °C; open squares: 1 h at 200 °C; open
diamond: 24 h at 200 °C.
and 5 show an increasing absorbance on annealing at
200 °C for 24 h. This can be attributed to the fact the
conjugated polymer was degraded at this temperature
on long heating, whereas the phenyl rings are not and
hence the relative increase in ring absorbance. A more
careful analysis of the photoluminescence data, how-
ever, reveals the emergence of a band below 560 nm
which together with the observation of a general de-
crease of the overall relative quantum yield by ca. 65%
in the polymer upon degradation is attributed to a
partial decomposition of the polymer (due to the forma-
tion of nonemissive defects). The control experiment
under inert conditions did not show any alterations in
the spectra and no decrease of the overall quantum
yield.
This comparison of the two polymers under extreme
thermal stress conditions clearly reveals the drastic
improvement of polymer 5 over polymer 4. It becomes
clearly evident that the dialkyl bridgeheads in polymer
4 are susceptible toward oxidation, which can be solved
by making a fully aryl-substituted poly(ladder-type
pentaphenylene) 5 to yield a blue-light-emitting polymer
highly stable against oxidative degradation.
To test this hypothesis, polymer 5 was also tested
under device conditions. OLEDs were prepared with
configuration ITO/PEDOT:PSS/polymer 5/Ca/Al. The
devices show an onset of the emission at ca. 4 V and a
blue emission (CIE coordinates 0.17, 0.09) with a
luminance typically above 200 cd/m2, which is stable
during several tens of minutes of operation at and up
to 14 V and a current density of up to ca. j ) 104 A/m2
under glovebox conditions. However, these unoptimized
single-layer devices show only moderate efficiencies
(0.1-0.5 cd/A), indicating that electron-transporting
layers are required to obtain maximum efficiency in the
device. Investigations into device optimization are un-
derway and will be reported separately. As can be seen
in Figure 5, biasing the device at rather high voltages
and current densities does not lead to any alteration in
the emission spectrum. Comparing these results to
polymer 4, where a minor degree of degradation has
been observed upon driving the device at high voltages
and current densities, these results clearly demonstrate
that the chemical structure of polymer 5 offers a
Figure 3. Normalized photoluminescence and absorption
spectra of a spin-coated polymer 4 film before and after
annealing in air. The film was measured directly after
preparation (filled squares), stored in the dark under ambient
atmosphere, and heated stepwise. Filled circles: after 1 h at
100 °C; open triangles: 1 h at 133 °C; filled triangles: 1 h at
166 °C; open squares: 1 h at 200 °C; open diamonds: 24 h at
200 °C.
wanted low-energy emission band at ca. 530 nm, spin-
coated films on glass substrates of both polymers 4 and
5 were exposed to oxygen under thermal stress condi-
tions in an accelerated lifetime test. The evolution upon
thermal stress in air of the photoluminescence for
polymer 4 is shown in Figure 3. Successive heating at
increasing temperatures (100, 133, 166, and 200 °C) on
a hot plate, each for 1 h under the influence of regular
atmosphere, leads to the well-known formation of oxida-
tive products in the form of ketonic defects with an
emission centered at 540 nm, which increases with
ongoing degradation. Note that simultaneous IR mea-
surements (not depicted) made on silicon wafers only
showed a very weak trace of a carbonyl stretching mode
emerging at 1721 cm-1. This is not surprising as the
absolute amount of ketonic defects formed this polymer
4 is already very low (<0.5%), due to the clean synthesis
and stable chemical structure of this polymer. Note that
under inert conditions, i.e., a dynamic vacuum of 10-6
mbar, no degradation of the polymer was detected.
By comparison, Figure 4 shows the identical thermal
degradation series under ambient conditions as shown
above now for the fully aryl-substituted polymer 5. As
can be clearly seen polymer 5 shows no sign of an
ongoing formation of a ketonic defect even after 24 h at
200 °C. From the absorption spectra, both polymers 4

9936 Jacob et al.
Macromolecules, Vol. 38, No. 24, 2005
Figure 5. I/V characteristics and normalized electroluminescence of an ITO/PEDOT/polymer 5/Ca/Al device operated at different
bias.
EL spectra were recorded using an ORIEL spectrometer
with an attached CCD camera. The current/luminance/voltage
(ILV) characteristics were recorded in a customized setup
using a Keithley 236 source measure unit for recording the
current/voltage characteristics while recording the luminance
using a calibrated photodiode attached to an integrating
sphere (Ulbrich).
considerable improvement and considerable potential as
an emissive material for fully stable pure blue-emitting
devices.
Conclusion
An efficient synthesis of a new poly(ladder-type pen-
taphenylene) 5 in which all the bridgeheads are fully
substituted with aryl groups has been developed. Single-
layer OLEDs with 5 showed stable blue emission with
a luminance typically over 200 cd/m2 which is stable
during several tens of minutes of operation at or below
14V. Accelerated stability test studies show remarkable
resistance to oxidation at the bridgeheads in oxidative
degradation experiments under thermal stress condi-
tions as well as during LED operation at high current
densities. These results confirm that arylation of the
bridgeheads in ladder-type polyphenylenes is a key
element in designing stable blue materials.
4′-Trimethylsilylbiphenyl-2-carboxylic Acid Methyl
Ester (6). 2-Bromomethylbenzoate (2.78 mL, 19.80 mmol)
4-trimethylsilylphenylboronic acid (5.00 g, 25.75 mmol), and
K2CO3 (3.56 g, 25.75 mmol) were mixed with 30 mL of H2O
and 60 mL of THF in a 250 mL Schlenk flask. The solution
was purged with argon for 10 min, and then Pd(PPh3)4 (458
mg, 0.40 mmol) was added and the reaction heated for 16 h at
80 °C. Removal of solvent followed by chromatography on silica
using 0-4% ethyl acetate in hexane as eluent gave the ester
1
6 as a colorless solid (5.48 g, 97%). H NMR: δ 7.72 (dd, J )
7.3 Hz, 1.0 Hz, 1H) 7.48 (m, 3H) 7.38-7.29 (m, 2H) 7.23 (m,
2H) 3.59 (s, 3H) 0.24 ppm (s, 9H). 13C NMR: δ 170.21, 143.71,
143.03, 140.61, 134.49 (2 peaks), 132.63, 132.40, 132.18,
131.05, 129.11 (2 peaks), 128.58, 53.22, 0.01 ppm. Elemental
analysis: Calcd: C, 71.79; H, 7.09. Found: C, 71.59; H, 7.13
Experimental Section
Synthesis of 2-Bromo-9,9-bis(4-octylphenyl)-9H-fluo-
rene (7). (a) 4-Octylbromobenzene (7.10 g, 26.37 mmol) was
dissolved in 50 mL of dry THF and cooled to -78 °C in an
acetone/dry ice bath. Then n-butyllithium (17.0 mL of 1.6 M
solution in hexanes, 27.25 mmol) was added dropwise, and the
mixture was stirred for 20 min. To this, a solution of 6 (2.50
g, 8.79 mmol) in 20 mL of dry THF was added dropwise, and
the reaction was stirred overnight. The reaction was then
quenched with brine and extracted into ether, and the extract
was washed with brine and dried over MgSO4. The crude
product was chromatographed on silica using 0-3% ethyl
acetate in hexane as eluent, to give the adduct (bis(4-
octylphenyl)-(4′-trimethylsilylbiphenyl-2-yl)methanol) as a col-
orless viscous oil (5.39 g, 95%). FDMS: m/z ) 632.10 (M +
All solvents were purified and freshly distilled prior to use
according to literature procedures. Dimethyl 2,5-dibromot-
erephthalate (9) was synthesized according to a literature
procedure. 1H and 13C NMR spectra were recorded on a Bruker
DRX 250 (250 and MHz, respectively). UV-vis data were
recorded on a Perkin-Elmer Lambda 9. Gel permeation chro-
matography (GPC) analysis was performed with PL gel
columns (103 and 104 Å pore widths) connected to a UV-vis
detector against poly-p-phenylene and polystyrene standards
with narrow weight distribution.
UV-vis transmission spectra were measured using a Per-
kin-Elmer Lambda 9 spectrophotometer. PL emission and
excitation spectra were recorded using a Shimadzu RF5301
spectrofluorometer or a SPEX Fluorolog 2 Type 212 spectrom-
eter.
1
H2O). H NMR: δ 7.32-7.15 (m, 4H) 7.11-7.00 (m, 9H) 6.80
(m, 3H) 2.86 (s, 1H) 2.61 (t, J ) 7.6 Hz, 4H) 1.62 (pentet, J )
7.3 Hz, 4H) 1.32 (m, 20H) 0.88 (t, J ) 6.6 Hz, 6H) 0.25 ppm
(s, 9H). 13C NMR: δ 147.08, 146.56, 144.22, 143.37, 142.58,
140.73, 134.31, 133.80, 131.41, 130.16, 129.33, 129.21, 128.23,
127.74, 84.60, 36.97, 33.43, 33.11, 33.06, 31.02, 30.82, 24.19,
15.39, -0.01 ppm.
(b) To bis(4-octylphenyl)-(4′-trimethylsilylbiphenyl-2-yl)-
methanol (5.30 g, 8.19 mmol) in 165 mL of THF, sodium
acetate (672 mg, 8.19 mmol) was added, and the mixture was
cooled to 0 °C. Then Br2 (2.74 g, 16.38 mmol) was added, and
The ITO-covered glass substrates for the PLEDs were
thoroughly cleaned in a variety of organic solvents and exposed
to an oxygen plasma dry cleaning step. PEDOT:PSS (Baytron
P from Bayer Inc.) layers were spin-coated under ambient
conditions and dried according to specifications by Bayer Inc.
under an inert atmosphere. The emissive polymer films were
spin-cast from solution and dried at 80 °C overnight in vacuo.
Metal electrodes were thermally deposited in a custom made
Balzers MED010 vacuum coating unit at base pressures of
below 2 × 10-6 mbar.

Macromolecules, Vol. 38, No. 24, 2005
Aryl-Substituted Poly(ladder-type pentaphenylene) 9937
the mixture was stirred for 20 min. Then triethylamine (3.34
g, 32.80 mmol) was added followed by 1.0 M sodium sulfite
solution. The product was extracted into ether, and the extract
was washed with brine and dried over MgSO4. Since mass
spectrometry indicated there was partial ring closure of the
product to form the fluorene derivative, the crude product was
used in the next step. The crude bromide was dissolved in 20
mL of dichloromethane and 0.20 mL of BF3‚etherate was
added. The reaction was stirred overnight and then quenched
with methanol. After removal of solvent, the crude product was
chromatographed on silica using hexane as eluent to give 7
(3.65 g, 72% for 2 steps). FDMS: m/z 622.10. 1H NMR: δ 7.75
(d, J ) 8.2 Hz, 1H) 7.66 (dd, J ) 7.9 Hz, 0.6 Hz) 7.50 (m, 2H)
7.35 (m, 3H) 7.05 (m, 8H) 2.55 (t, J ) 7.6 Hz, 4H) 1.56 (m,
4H) 1.36-1.26 (m, 20H) 0.87 ppm (t, J ) 6.9 Hz, 6H).
and cooled in an ice bath. Then Br2 liquid (0.22 g, 1.36 mmol)
was added and stirred for 14 h. FDMS analysis showed the
formation of the dibromide quantitatively at m/z 2095.00. The
reaction was quenched with sodium sulfite solution and
worked up to obtain a crude product which was recrystallized
from THF and ethanol (product was first dissolved in 50 mL
of THF and then 100 mL of ethanol was added). The dibromide
12 was isolated as light yellow needles (1.16 g, 98%). 1H
NMR: 7.70 (s, 2H) 7.65 (s, 2H) 7.64 (s, 2H) 7.54 (d, J ) 7.9
Hz, 2H) 7.44 (m, 4H) 7.21-7.04 (m, 32H) 2.56 (t, J ) 7.6 Hz)
1.58 (m, 16H) 1.42-1.19 (m, 80H) 0.89 ppm (t, J ) 6.0 Hz,
24H). Elemental Analysis: Calcd: C, 83.71; H, 8.66. Found:
C, 83.75; H, 8.71
The bromination was also carried out using CuBr2 on
alumina although this reaction was slow compared to that
using of Br2.
2-[9,9-Bis(4-octylphenyl)-9H-fluorene-2-yl]-4,4,5,5-tet-
ramethyl-[1,3,2]-dioxaborolane (8). A solution of the bro-
mide 7 (2.00 g, 3.21 mmol) in 60 mL of dry THF was cooled to
-78 °C. Then, 2.21 mL of 1.6 M n-butyllithium was added,
and the mixture was stirred for 20 min. To this, 2-isopropoxy-
4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane (0.84 g, 4.49 mmol)
was added, and the reaction was stirred overnight. After 16
h, the reaction was quenched with saturated salt, the product
was extracted into ether, and the extract was washed with
brine and dried over MgSO4. After removal of solvent, the
residue was chromatographed on silica using 0-2% ethyl
acetate in hexane as eluent to isolate the boronate 8 as a
Synthesis of the Pentaphenylene Polymer 5. A mixture
of bis(1,5-cyclooctadiene)nickel(0) (221 mg, 0.80 mmol), cyclo-
octadiene (0.10 mL, 0.80 mmol), 2,2′-bipyridine (125 mg, 0.80
mmol), DMF (5 mL), and toluene (3 mL) in a Schlenk flask
was heated at 60 °C for 20 min. Then the monomer (0.70 g,
0.33 mmol) dissolved in 12 mL of toluene was added dropwise,
and the reaction was heated at 75 °C for 48 h. Bromobenzene
(0.10 mL) was then added, and the reaction mixture was
heated for an additional 6 h. The reaction mixture was poured
dropwise into 250 mL of methanol whereupon the polymer
precipitated out as pellets. The polymer was filtered off and
then suspended in 300 mL of 1:1 methanol and concentrated
HCl for 6 h. The dried polymer was then subjected to Soxhlet
extraction with acetone for 24 h and then redissolved in 30
mL of THF. This was then added dropwise to a mixture of
150 mL of methanol and 150 mL of 25% aqueous ammonia.
The precipitated polymer 5 was filtered off, washed with
methanol, and dried to give a yellow solid (555 mg, 86%). GPC
analysis: Mn ) 2.83 × 104; D ) 2.65 (PPP standard), and Mn
) 4.45 × 104; D ) 3.53 (PS standard). TGA analysis: stable
up to 350 °C.
1
colorless solid (1.68 g, 78%). FDMS: m/z 669.10 H NMR: δ
7.85 (m, 4H) 7.46-7.31 (m, 3H) 7.14 (m, 8H) 2.61 (t, J ) 7.6
Hz, 4H) 1.63 (pentet, J ) 7.3 Hz, 4H) 1.37 (m, 32H) 0.95 ppm
(t, J ) 6.9 Hz, 6H). 13C NMR: δ 153.15, 151.77, 143.80, 142.33,
140.59, 134.94, 132.68, 129.02, 128.76, 128.25, 126.95, 121.42,
120.37, 84.60, 65.75, 36.30, 32.74, 32.34, 30.31, 30.09, 25.55,
25.48, 23.52, 14.74 ppm.
Synthesis of the Pentaphenylene Diester 10. Dimethyl
2,5-dibromoterephthalate (9) (346 mg, 0.98 mmol), the bor-
onate 8 (1.58 g, 2.36 mmol), and K2CO3 (327 mg, 2.36 mmol)
were dissolved in 30 mL of THF and 10 mL of H2O in a Schlenk
flask. The reaction was purged with argon for 15 min, and then
tetrakis(triphenylphosphine)palladium (45 mg, 0.04 equiv) was
added and the reaction was heated at 85 °C for 14 h. Removal
of solvent followed by chromatography on silica using 0-4%
ethyl acetate in hexane as eluent gave the pentaphenylene
diester 10 as a white solid (1.14 g, 91%). FDMS: m/z 1276.40.
1H NMR: δ 7.87 (d, J ) 7.9 Hz, 2H) 7.83 (d, J ) 7.9 Hz, 2H)
7.78 (s, 2H) 7.45-7.31 (m, 10H) 7.07 (m, 16H) 3.4 (s, 6H) 2.54
(t, J ) 7.6 Hz, 8H) 1.56 (pentet, J ) 7.0 Hz, 8H) 1.28 (m, 40H)
0.88 ppm (t, J ) 6.3 Hz, 12H). 13C NMR: δ 168.83, 152.69,
152.32, 143.77, 142.36, 141.57, 140.51, 140.33, 140.02, 134.21,
132.54, 129.02, 128.70, 128.64, 128.39, 128.29, 127.15, 126.88,
121.14, 120.9865.76, 52.73, 36.21, 32.66, 32.30, 30.22 (2 peaks),
30.02, 23.44, 14.64 ppm. Elemental Analysis: Calcd: C, 86.61;
H, 8.37. Found: C, 86.63; H, 8.41.
Acknowledgment. This work was supported by the
Bundesministerium fu¨r Bildung und Forschung (Projects
13N8165 OLAS and 13N8215 OLED) and by Dupont
Displays. J.J. acknowledges the Alexander von Hum-
boldt Stiftung for the grant of a Research Fellowship.
The CDL-AFM is a key member of the long-term AT&S
research strategies.
Supporting Information Available: TGA and DSC ther-
mograms for polymer 5. This material is available free of
charge via the Internet at http://pubs.acs.org.
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up was used as such in the next step. This crude product was
dissolved in 30 mL of dichloromethane, and 0.20 mL of BF3‚
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instantaneously and then became light yellow after 10 min.
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1
for 2 steps). FDMS: m/z 1937.20. H NMR: δ 7.71-7.64 (m,
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8H), 7.34-6.97 (m, 38H), 2.54 (m, 16H), 1.57 (m, 16H), 1.40-
1.15 (m, 80H), 0.88 ppm (t, 24H, J ) 6.30 Hz). Elemental
Analysis: Calcd: C, 90.53; H, 9.47. Found: C, 90.61; H, 9.45
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