Preparation of poly(silylene-p-phenylene)s containing a pendant fluorophor and their applications to PL imaging

Article abstract of DOI:10.1021/ma040108p

Poly(silylene-p-phenylene)s bearing an anthrylethynyl, pyrenylethynyl, or terthienyl group as the pendant were obtained in moderate yield, by substitution reactions of poly[ethoxy(methyl)silylene-p-phenylene] with the corresponding organolithium reagents in THF. The polymers exhibited photoluminescent (PL) properties in solutions as well as in the films. They were photoactive and irradiation of the films in air with a low-pressure mercury lamp led to a decrease of PL efficiencies, being applicable to PL imaging of the films. The present polymers can be used also as hole-transporting materials in double-layer electroluminescent (EL) devices and the devices with the structure of ITO/polymer film/Alq₃/Mg-Ag emitted a green EL arising from Alq₃ emission.

Full text of DOI:10.1021/ma040108p

730
Macromolecules 2005, 38, 730-735
Preparation of Poly(silylene-p-phenylene)s Containing a Pendant
Fluorophor and Their Applications to PL Imaging
Joji Ohshita,* Taisuke Uemura, Dong-Ha Kim, and Atsutaka Kunai*
Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University,
Higashi-Hiroshima 739-8527, Japan
Yoshihito Kunugi
Division of Materials Science, Faculty of Integrated Arts and Sciences, Hiroshima University,
Higashi-Hiroshima 739-8521, Japan
Masaya Kakimoto
Osaka R & D Laboratories, Sumitomo Electric Industries, Limited,
1
-1-3 Shimaya, Konohana-ku, Osaka 554-0024, Japan
Received June 14, 2004; Revised Manuscript Received October 26, 2004
ABSTRACT: Poly(silylene-p-phenylene)s bearing an anthrylethynyl, pyrenylethynyl, or terthienyl group
as the pendant were obtained in moderate yield, by substitution reactions of poly[ethoxy(methyl)silylene-
p-phenylene] with the corresponding organolithium reagents in THF. The polymers exhibited photo-
luminescent (PL) properties in solutions as well as in the films. They were photoactive and irradiation
of the films in air with a low-pressure mercury lamp led to a decrease of PL efficiencies, being applicable
to PL imaging of the films. The present polymers can be used also as hole-transporting materials in
double-layer electroluminescent (EL) devices and the devices with the structure of ITO/polymer film/
Alq3/Mg-Ag emitted a green EL arising from Alq3 emission.
Introduction
imaging materials, we prepared poly(silylene-p-phen-
ylene)s bearing an anthrylethynyl, pyrenylethynyl, or
terthienyl group as the pendant by substitution reac-
tions of poly[ethoxy(methyl)silylene-p-phenylene] with
the corresponding organolithium reagents. In these
polymers, silyl-substitution was anticipated to increase
Organic photoluminescent (PL) materials are of im-
portance in the area of organic optical devices. In
particular, those applicable to PL imaging have at-
tracted a recent interest. Several approaches to pattern
PL images have been made, most commonly by using
6
1
the fluorescence intensities of the fluorophors, and to
acid-sensitive fluorescent dyes. In this process, polymer
accelerate the photo oxidation of the fluorophors making
it possible to use the polymer films for sensitive PL
films containing an acid sensitive fluorescent dye and
a photoacid generator are irradiated through a photo
mask then the resulting films are heated to induce the
reaction of the fluorophor with proton in the irradiated
area, leading to changes of the PL color and/or efficien-
cies. Recently, a new methodology was reported, in
which compounds having both a fluorescent site and a
quenching nitroxide unit were irradiated in the presence
7
imaging. In addition, sterically large silylenephenylene
units would hinder the π-π stacking of the fluorophores
leading to high quantum yields of the polymers. Ap-
plications of the polymers to hole-transporting materials
in electroluminescence (EL) devices also were studied.
The π-conjugated fluorophors with electron-donating
silyl-substitution were expected to possess high-lying
highest occupied orbital, giving rise to high hole-affinity
of the present polymers.
2
of a radical initiator. The photogenerated radical
coupled with the nitroxide to increase the fluorescence
efficiencies. In these processes, the fluorophores and
reagents were used in polymer matrixes in order to
avoid the staking of fluorophores that would decrease
the PL efficiencies. In general, however, it may be
difficult to avoid phase separation as well as aggregation
of the fluorophores in the matrixes during preparation,
operation, or storage of the films, which cause a
significant decrease of the PL efficiencies. Although
applications of stilbene-type fluorophores, whose pho-
tolysis leads to nonemissive [2 + 2] dimers, to PL
imaging have been also reported, these must be used
Results and Discussion
Polymer Synthesis. Poly(silylene-p-phenylene)s bear-
ing a pendant fluorophor (1-3) were synthesized as
shown in Scheme 1. The reactions of poly[ethoxy-
(methyl)silylene-p-phenylene] (Mw ) 13500, Mn ) 8500),
prepared by Grignard coupling of bromophenyl(di-
4
ethoxy)methylsilane with the corresponding organo-
lithium reagents, afforded the expected polymers, as
summarized in Table 1. As shown in Table 1, incorpora-
tion of the fluorophores into the polymers (x/y) could be
controlled by changing the polymer/reagent ratio, but
attempts to obtain fully substituted polymers were
unsuccessful, even when 2-fold excess of the reagents
were employed.
3
in forms of well-aligned LB films.
Recently, we demonstrated that nucleophilic substitu-
tion of poly(ethoxysilylenephenylene)s provides
a
convenient approach to variously substituted poly-
4
(
silylenephenylene)s. In these reactions, highly elec-
trophilic properties of the EtO-Si bond originate the
The molecular weights of the polymers were deter-
mined by gel permeation chromatography (GPC), rela-
tive to polystyrene standards. The values were in good
5
smooth substitution on the polymers. In the hope of
obtaining single component and simply accessible PL
1
0.1021/ma040108p CCC: $30.25 © 2005 American Chemical Society
Published on Web 01/04/2005

Macromolecules, Vol. 38, No. 3, 2005
Preparation of Poly(silylene-p-phenylene)s 731
Table 1. Synthesis and Properties of Polymers
x/ya
1H NMR
Φ
polym
reagent/equiv
EA
yield /%
mp/°C
Mwb (Mn/Mn)
in film
in THF
0.48
1a
1b
1c
1d
1e
0.5
0.6
0.8
1.0
2.0
14/86
28/72
32/68
49/51
73/27
15/85
28/72
35/65
49/51
73/27
77
91
86
93
61
128-135
142-153
170-179
>300
16000 (1.6)
17000 (2.6)
30000 (3.6)
18000 (1.9)
38000 (4.6)
0.05-0.07
0.02-0.03
0.02-0.03
0.02-0.03
<0.01
0.23
0.12
>300
2
2
2
2
a
b
c
0.45
0.55
0.83
2.0
16/84
23/77
30/70
78/22
15/85
22/78
30/70
78/22
45
37
53
76
138-147
146-152
149-158
218-227
18000 (1.8)
26000 (2.7)
37000 (2.8)
13000 (1.6)
0.44-0.61
0.62-0.73
0.34-0.41
0.07-0.08
0.34
0.13
d
3
3
3
3
3
a
b
c
d
e
0.20
0.26
0.35
0.65
1.0
12/88
17/83
28/72
50/50
73/27
12/88
23/77
28/72
50/50
73/27
86
90
91
87
78
85-93
14000 (1.6)
20000 (1.6)
21000 (1.7)
20000 (1.6)
19000 (1.7)
0.02-0.03
0.03-0.04
0.01-0.02
0.01-0.02
0.01-0.02
105-112
112-115
119-123
133-137
0.11
0.08
a
1
b
The x/y ratio was determined by the H NMR spectrum or elemental analysis. Determined by GPC, relative to polystyrene standards.
-
5
Scheme 1
fluorescence spectra of THF solutions (2.0 × 10
silylene-phenylene unit mol/L) and spin-coated films
of some of the polymers, 1-3. Fluorescence maxima of
the corresponding monomeric compounds are shown in
Chart 1, for comparison. As can be seen in Figure 1a,
the fluorescence spectra of polymers 1 in THF revealed
intense bands at 400-480 nm, ascribed to the emission
from isolated ethynylanthracene fluorophores with a
broad shoulder over 500 nm whose intensity was
relatively enhanced by increasing x/y ratios. This broad
shoulder may be ascribed to the eximer emission arising
from stacking of the fluorophores and its relative
intensity was further enhanced by measuring the
spectra in the solid state (Figure 1b). In contrast to this,
the spectra of polymers 2 showed a broad maximum at
about 500 nm as the major peak even in the solutions
(Figure 1c), indicating the favored eximer formation of
ethynylpyrene fluorophores. The maxima of the films
were slightly red-shifted as the x/y ratios increased. To
know more about the origin of the fluorescence bands,
we measured the PL lifetimes. Thus, monitoring PL
decay of polymer 2b in THF at 400 nm gave τ1 ) 3.7
ns, while the PL at 500 nm underwent decay with τ1 )
agreement with those calculated from the molecular
weights of the starting polymer, but the poly dispersities
(Mw/Mn) were rather large, indicating that some side
reactions including the cleavage of the polymer back-
bone and cross-linking reactions had occurred to an
extent. Polymers 1-3 were soluble in common organic
solvents, such as aromatic solvents, ethers, and chlo-
rocarbons, but barely soluble in alcohols and saturated
hydrocarbons. They could be spin-coated to thin solid
films from the solutions. The polymer with the higher
x/y ratio melted at the higher temperature. Introduction
of more rigid and large π-conjugated substituents in
place of the ethoxy groups and/or inerchain interaction
by π-stacking as indicated by the emission spectra of
the polymers (see bellow) seemed to be responsible for
the increase. For large increase of melting temperatures
going from 1c to 1d is probably due to the cross-linking
reactions during the measurements. In fact, DSC analy-
sis of polymer 1d in a nitrogen atmosphere revealed a
broad exothermic peak around 250 °C and the polymer
became hardly soluble after heating at 280 °C.
PL Properties of Polymers 1)3. UV spectra of
polymers 1-3 revealed absorption bands due to the
fluorophores in addition to that of silylene-phenylene
backbone around at 240 nm. The absorption band of the
silylene-phenylene unit did not move depending on the
fluorophor, indicating that no evident interaction took
place between them. The polymers exhibited strong
photofluorescence and emitted a blue green or green
light when irradiated with a low-pressure mercury lamp
in solutions as well as in films. Figure 1 represents
21.3 ns. The fluorescence spectra of polymers 3 revealed
a strong band and a shoulder, presumably due to the
isolated and stacked fluorophores, respectively, in solu-
tions (Figure 1e), the latter of which was relatively
enhanced in the solid state (Figure 1f), similar to
polymers 1.
In Table 1, relative fluorescence quantum efficiencies
of spin-coated films of polymers 1-3 are also sum-
marized. The values were determined by using 9,10-
diphenylanthracene dispersed in a polystyrene film as
8
a standard. Since the fluorescence intensities of the
polymer films, even that of the standard film, were
unstable and were not well reproducible, we could not
determine the exact values. In Table 1, therefore, only
the value ranges obtained from at least 5 times mea-
surements are listed. The efficiencies tended to decrease
as increasing x/y ratios. High quantum efficiencies were
obtained for polymers 2 with the best value of 0.62-
0.73 for 2b (x/y ) 22/78). Enhanced fluorescence o9f
pyrene by the formation of its excimer is well-known.
Although the origin of a decrease of the quantum
efficiencies on going from 2b to 2d is unclear, it may be
explained by self-quenching in the solid states with high
concentrations of the fluorophor. Films of polymers 1
and 3, in contrast, exhibited much lower quantum
efficiencies.

732 Ohshita et al.
Macromolecules, Vol. 38, No. 3, 2005
-
5
Figure 1. Fluorescence spectra of polymers 1-3 in THF of 2.0 × 10 silylene-phenylene unit mol/L (left) and in films (right).
Chart 1
Patterning of PL Images. Spin-coated films of
polymers 1-3 on quartz plates were irradiated with a
low-pressure mercury lamp in air and the reaction
progress was monitored by UV and fluorescence spectra,
as illustrated for polymer 2b (x/y ) 22/78) in Figure 2.
After 15 min of irradiation, the UV and fluorescence
bands almost disappeared and the IR spectra of the
resulting films showed the absorption bands ascribed
-
1
to siloxane and carbonyl units at 1100 and 1745 cm
,
respectively, indicating that some oxidation reactions
had occurred. When an irradiated film of 2b was
dissolved in deuteriochloroform and was analyzed with
1
respect to the H NMR spectrum, all aromatic protons
disappeared and new multiple olefin signals appeared
Figure 2. Changes upon irradiation of a film of polymer 2b
in (a) UV and (b) fluorescence spectra.
at 5.1-5.8 ppm, together with those at 0.8-0.9, 1.4-
2
.1, and 3.3-4.2 ppm. These results clearly indicated
that not only the phenylene group but also the ethyn-
ylpyrene fluorophor were decomposed by photooxida-
tion. Although we have not yet obtained enough data
to discuss detailed mechanism for the photodegradation
of the polymers, similar photodegradation has been
reported for silylene-diethynyleneanthracene and

Macromolecules, Vol. 38, No. 3, 2005
Preparation of Poly(silylene-p-phenylene)s 733
Figure 3. PL images prepared by irradiation of spin-coated films of (a) 1b, (b) 2b, (c) 2d, and (d) 3a in air.
Figure 4. Patterned PL lines prepared by using polymer 2b with the thickness of (a) 250 µm and (b) 20 µm.
silylene-diethynylenepyrene polymers, previously.10 Pre-
sumably, silyl radicals arising from photoinduced
homolytic scission of Si-C bonds added to oxygen,
leading to silyl peroxides that oxidized fluorophors. A
similar mechanism has been proposed previously for the
photooxidation of poly[4-(trimethylsilylmethyl)styrene]
7
a
in air.
The irradiated films of polymers 1-3 were no longer
emissive and irradiation through a photo mask led to
clear patterning of PL images. Examples that were
produced by using polymers 1b, 2b, 2d, and 3a, respec-
tively, are presented in Figure 3. Fine patterning was
also possible and emissive line with the width of 20 µm
could be produced as shown in Figure 4.
Figure 5. PL image prepared by irradiation of a film of poly-
[
ethoxy(methyl)silylene-p-phenylene] containing (trimethyl-
silylethynyl)pyrene in air.
To know how the binding of fluorophores as the
polymer pendant affects the PL properties of the films,
we examined patterning of a PL image by employing
9
-(trimethylsilylethynyl)pyrene blended in poly[ethoxy-
(
methyl)silylene-p-phenylene] in a ratio of 22/78. Thus,
the blend was spin-coated on a quartz plate and the film
was irradiated through a photomask. Figure 5 shows
the resulting PL image that appears rather heteroge-
neous with nonemissive spots in the nonirradiated area,
in contrast to those of polymers 1-3 shown in Figures
Figure 6. Luminance-voltage (L-V) plots of EL devices with
the structure of ITO/polymer film/Alq3/Mg-Ag.
3
and 4.
Utilization of Polymers 1)3 as Hole-Transports
in EL Devices. We next examined polymers 1-3
having the highest x/y ratio among the respective
polymers, as hole-transporting materials in EL devices.
Figure 6 represents luminance-voltage (L-V) plots of
EL devices with the structure of ITO/polymer film/Alq3/
Mg-Ag where Alq3 (tris(8-quinolinolato)aluminum(III))

734 Ohshita et al.
Macromolecules, Vol. 38, No. 3, 2005
1
was used as the electron-transporting-emitter, and ITO
of the H NMR spectra that are consistent with the values
based on the combustion elemental analysis within the error
range.
(indium-tin-oxide) and Mg-Ag are the anode and
cathode, respectively. The devices emitted a green light
arising from Alq3 emission, when bias voltage exceeded
Preparation of Polymers 2a)d. Polymers 2a-d were
obtained in the same manner as for polymer 1e, using
-ethynylpyrene instead of 9-ethynylanthracene. In these
5
-6 V. No emission from the polymers was observed at
1
all. The device with polymer 3e (x/y ) 73/27) showed
reactions, 1,4-dipyranylbutadiyne that could not be separated
from the polymers by reprecipitation was formed as a byprod-
uct in approximately 5-10% yield. The polymers, therefore,
were subjected to preparative GPC for purification. Data for
the best results among the devices examined, and the
2
maximal luminance reached 3000 cd/m at 11 V. At this
voltage, the current density of the device reached 500
2
mA/cm . The present device performance is a little
2
c (for NMR, data only for the substituted unit are given):
inferior, but comparable to a similar device having a
film of poly(vinylcarbazole) that is known as a common
hole-transport, in place of the silicon polymer film.11
Devices without the Alq3 layer (ITO/polymer film/
Mg-Ag) emitted no detectable luminance up to 30 V of
the bias voltage.
In conclusion, we found that nucleophilic substitution
reactions of poly(ethoxysilylenephenylene) readily pro-
ceeded to give fluorophor-substituted polymers. Their
applications to PL imaging as well as hole-transporting
materials in EL device systems were demonstrated.
Poly(silylenephenylene) seems to be useful as the back-
bone of functionality polymeric materials. Studies to
introduce other functional substituents on the polymer
system are underway.
IR νCtC 2150 cm-1
;
1
H NMR (δ in CDCl ) 0.88 (s, 3H, MeSi),
3
7.66-8.14 (m, 8H, pyrene), 7.82 (s, 4H, phenylene), 8.55 (br s,
13
1H, pyrene); C NMR (δ in CDCl
3
) -1.95 (SiMe), 95.82, 107.57
(
CtC), 116.94, 124.00, 124.20, 124.30, 125.38, 125.73(2C),
1
1
26.21, 127.12, 128.42, 128.59, 130.11, 130.85, 131.03, 131.59,
2
9
32.45 (pyrene), 133.78-133.92 (m), 136.95 (phenylene); Si
) -25.38. Anal. Calcd for ((C25
: C, 75.87; H, 6.09. Found: C, 75.60; H, 6.25.
NMR (δ in CDCl
3
9 12
H16Si)0.30(C H -
OSi)0.70)
n
Preparation of 5-Ethyl-5′′-bromo-2,2′:5′,2′′-terthiophene.
In dark, NBS (20.20 g, 0.112 mol) was slowly added to a well-
stirred solution of 5-ethyl-2,2′:5′,2′′-terthiophene (29.5 g, 0.112
mol) in 500 mL of chloroform at 0 °C, and the mixture was
stirred for 5 h. To this was added 300 mL of water and the
organic layer was separated and the aqueous layer was
extracted by chloroform. The organic layer and the extracts
2 4
were combined, and dried over anhydrous Na SO . After the
solvent was evaporated, the residue was recrystallized from
Experimental Section
hot ethanol twice to give 31.9 g (80% yield) of 5-ethyl-5′′-bromo-
2
,2′:5′,2′′-terthiophene as bright yellow solid: mp 146-147 °C;
General Methods. All reactions were carried out under an
inert atmosphere. THF used as the reaction solvent was dried
over sodium-potassium alloy and distilled just before
+
79 1
MS m/z 354 (M for Br); H NMR (δ in CDCl
3
) 1.32 (t, 3H, J
)
7.6 Hz), 2.83 (2H, q, J ) 7.6 Hz), 6.69 (d, 1H, J ) 3.2 Hz),
1
3
6
1
1
3
.87-6.98 (m, 5H); C NMR (δ in CDCl ): 15.83, 23.53, 110.79,
4
use. Poly[ethoxy(methyl)silylene-p-phenylene] and ethynyl-
23.52, 123.64, 124.20, 124.53, 130.65, 134.12, 134.38, 137.31,
38.76, 147.38 (one carbon may overlap). Anal. Cacld for
1
2
anthracene were prepared as reported in the literature.
Ethynylpyrene was prepared in a fashion similar to that for
C
14
H
11BrS
3
: C, 47.32; H, 3.12. Found: C, 47.22; H, 3.11.
Preparation of Polymers 3a)e. In a 50 mL two necked
flask were placed 0.22 g (0.61 mmol) of 5-ethyl-5”-bromo-
,2′:5′,2′′-terthiophene and 10.0 mL of THF, and the flask was
1
3
ethynylanthracene. NMR spectra were recorded on a JEOL
model JNM-LA 400 spectrometer. IR spectra were measured
on a Shimadzu FT-IR model 8700 spectrometer. UV and
fluorescence spectra were measured on Hitachi U-3210 and
Shimadzu RF5000 spectrophotometers, respectively. Molecular
weights of the polymers were determined by gel-permeation
chromatography relative to polystyrene standards, using Sho-
dex 806 and 804 columns that were connected in series, eluting
with THF.
2
cooled to -78 °C. To this was added dropwise 0.39 mL (0.61
mmol) of a 1.58 M n-butyllithium-hexane solution and the
resulting mixture was stirred at room temperature for 3 h. A
solution of 0.10 g of poly[ethoxy(methyl)silylene-p-phenylene]
(
w n
M ) 13500, M ) 8500) in 3.0 mL of THF was then added
slowly to the mixture at -78 °C, and the mixture was stirred
at room temperature for 12 h. After hydrolization with water,
the organic layer was separated and the aqueous layer was
extracted with chloroform. The organic layer and the extracts
were combined and dried over anhydrous magnesium sulfate.
After evaporation of the solvents, the residue was reprecipi-
tated twice from chloroform-ethanol to give 0.16 g of polymer
Preparation of Polymers 1a)e. In a 100 mL two necked
flask were placed 0.50 g (2.50 mmol) of 9-ethynylanthracene
and 20.0 mL of THF and the flask was cooled to -78 °C. To
this was added dropwise 2.72 mL (2.50 mmol) of a 0.92 M
methyllithium-diethyl ether solution. After this was stirred
at room temperature for 3 h, a solution of 0.21 g of poly[ethoxy-
(methyl)silylene-p-phenylene] (M
w n
) 13500, M ) 8500) in 6.0
3
e (78% yield). Data for 3e (for NMR, data only for the
mL of THF was added slowly to the mixture at -78 °C, and
the resulting mixture was stirred at room temperature for 12
h. After hydrolization with water, the organic layer was
separated and the aqueous layer was extracted with chloro-
form. The organic layer and the extracts were combined and
dried over anhydrous magnesium sulfate. After evaporation
of the solvents, the residue was reprecipitated twice from
chloroform-ethanol to give 0.21 g of polymer 1e (x/y ) 73/27):
1
3
substituted unit are given): H NMR (δ in CDCl ) 0.83 (s, 3H,
MeSi), 1.30 (t, 3H, J ) 7.58 Hz, Et), 2.82 (q, 2H, J ) 7.58 Hz,
Et), 6.64 (br s, 1H, thiophene), 6.93 (br s, 2H, thiophene), 7.01
(
br s, 1H, thiophene), 7.13 (br s, 1H, thiophene), 7.18 (br s,
1
H, thiophene), 7.57 (s, 4H, phenylene, overlapping with a
13
signal of the unsubstituted unit); C NMR (δ in CDCl
MeSi), 15.82 (CH -CH ) 23.49 (CH -CH ), 123.41, 123.54,
124.12, 124.78, 133.94, 135.17, 143.85, 147.06 (thiophene),
3
) -2.57
(
3
2
2
3
-
1
IR νCtC 2138 cm . Anal. Calcd for ((C23
9 12
H16Si)0.73(C H -
2
9
1
34.27, 137.05 (phenylene); Si NMR (δ in CDCl
Anal. Calcd for ((C21 : C, 64.16; H,
.97. Found: C, 64.37; H, 5.05.
Fabrication of EL Devices. A film of the polymer with
3
) -15.69.
OSi)0.27)
n
: C, 82.95; H, 5.40. Found: C, 82.89; H, 5.22. NMR
18 3 9 n
H S Si)0.73(C H12OSi)0.27)
spectra of 1e revealed signals ascribed to both the units of
anthrylethynyl- and ethoxy-substituted units, the later of
which appeared at almost the same positions as those of the
4
starting polymer. Data for the anthrylethynyl-substituted
an approximate thickness of 50 nm was prepared by spin-
coating (2000 rpm) from a solution of polymer in chloroform
(5 g/L) on an anode, indium-tin-oxide (ITO) coated on a glass
substrate (Nippon Sheet Glass Co.). An electron-transporting-
emitting layer with a thickness of 50 nm was then prepared
by vacuum deposition of tris(8-quinolinolato)aluminum(III)
1
unit: H NMR (δ in CDCl
3
) 0.90 (s, 3H, MeSi), 7.45-7.63 (m,
4
H, anthracene), 7.83 (br s, 2H, anthracene), 7.90 (s, 4H,
phenylene), 8.36 (br s, 1H, anthracene), 8.53 (br s, 2H,
1
3
anthracene); C NMR (δ in CDCl
3
) -1.83 (SiMe), 101.74,
05.37 (CtC), 116.41, 125.61, 126.60, 126.94, 128.60, 130.89,
33.14, 133.94 (anthracene), 134.18, 137.05 (phenylene); 29Si
1
1
-5
(Alq3) at 1 × 10 Torr on the polymer film. Finally a layer of
NMR (δ in CDCl
Polymers 1a-1d were obtained in a fashion similar to that
given above. Their x/y ratios were determined by integration
3
) -25.16.
magnesium-silver alloy (Mg-Ag) with an atomic ratio of 10:1
was deposited on the Alq layer surface as the top electrode at
-
5
1 × 10 Torr.

Macromolecules, Vol. 38, No. 3, 2005
Preparation of Poly(silylene-p-phenylene)s 735
Acknowledgment. This work was supported by a
Grant-in-Aid for Scientific Research (B) (No. 16350102)
from the Ministry of Education, Science, Sports, and
Culture of Japan, to which our thanks are due.We thank
Sankyo Kasei Co., Ltd., and Tokuyama Co., Ltd., for
financial support. We also thank Prof. Y. Harima for
the measurements of PL lifetimes.
(6) Enhanced fluorescence intensities by silyl-substitution has
been often observed. For example, see: (a) Maeda, H.; Inoue,
Y.; Ishida, H.; Mizuno, K. Chem. Lett. 2001, 1224. (b)
Kyushin, S.; Ikarugi, M.; Goto, M.; Hiratsuka, H.; Matsumoto,
H. Organometallics 1996, 15, 1067.
(7) For accelerated photooxidation of π-conjugated compounds
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