Silylene-spaced diphenylanthracene derivatives as blue-emitting materials

Article abstract of DOI:10.1016/j.jorganchem.2006.01.016

A novel series of blue emitting silylene-spaced diphenylanthracene derivatives have been synthesized and characterized. The rhodium-catalyzed hydrosilylation of bis[4-(dimethylsilyl)phenyl]anthracene 3-4 yielded stable 9,10-disubstituted (E)-divinylsilylene-diphenylanthracene products 7-10 and salt elimination reaction of bis[4-(chlorodimethylsilyl)phenyl]anthracene 5-6 gave 9,10-disubstituted disilyldiphenylanthracene compounds 11-14. They are fluorescent in the blue region with good quantum efficiencies. The rhodium-catalyzed polyaddition including 2-tert-butyl-9,10-bis[4-(dimethylsilyl) phenyl]anthracene (4) afforded the nonconjugated copolymer 15.

Full text of DOI:10.1016/j.jorganchem.2006.01.016

Journal of Organometallic Chemistry 691 (2006) 1887–1896
www.elsevier.com/locate/jorganchem
Silylene-spaced diphenylanthracene derivatives
as blue-emitting materials
a
a
a
b,
c
Taegweon Lee , Kyu Ho Song , Il Jung , Youngjin Kang *, Soo-Hyoung Lee ,
b,
a,
*
Sang Ook Kang *, Jaejung Ko
a
Department of Chemistry, Korea University, Jochiwon, Chungnam 339-700, Republic of Korea
Division of Science Education, Kangwon National University, Chuncheon 200-701, Republic of Korea
Optoelectronic Materials Research Center, Korea Institute of Science and Technology, Seoul 130-650, Republic of Korea
b
c
Received 1 November 2005; received in revised form 6 January 2006; accepted 10 January 2006
Available online 20 February 2006
Abstract
A novel series of blue emitting silylene-spaced diphenylanthracene derivatives have been synthesized and characterized. The
rhodium-catalyzed hydrosilylation of bis[4-(dimethylsilyl)phenyl]anthracene 3–4 yielded stable 9,10-disubstituted (E)-divinylsilylene–
diphenylanthracene products 7–10 and salt elimination reaction of bis[4-(chlorodimethylsilyl)phenyl]anthracene 5–6 gave 9,10-disub-
stituted disilyldiphenylanthracene compounds 11–14. They are fluorescent in the blue region with good quantum efficiencies. The
rhodium-catalyzed polyaddition including 2-tert-butyl-9,10-bis[4-(dimethylsilyl)phenyl]anthracene (4) afforded the nonconjugated
copolymer 15.
Ó 2006 Elsevier B.V. All rights reserved.
Keywords: Electroluminescent; Silylene-spaced diphenylanthracene; Rhodium-catalyzed hydrosilylation
1. Introduction
host for downhill energy transfer to green- or red-emitting
materials [4]. Diphenylanthracene derivatives, in particular,
have been often used as blue emitter in OLEDs, because
they have shown to have good physical properties, such as
maximum luminescence, power efficiency, current effi-
ciency, and external quantum efficiency [5]. It is known that
diphenylanthracene has high photoluminescence quantum
yield, good electrochemical property and orthogonal struc-
ture between anthracene core and substituted peripheral
phenyl ring [6]. Therefore, the devices containing diphenyl-
anthracene as an emitter are expected to show higher elec-
troluminescence efficiency, long lifetime, and deep blue
color. Because of these advantages, diphenylanthracene
became our blue luminophore of choice.
Organic light-emitting devices (OLEDs) have attracted
great attention in material science since the initial work
was first reported in 1987 by Tang and Vanslyke because
of their potential applications in full-color flat-panel dis-
plays [1]. For high-performance full-color displays, the
development of three elemental colors of red-, green-, and
blue-emitting materials with good color purity and high effi-
ciency is necessary. After two decades of active research, a
number of red, green, and blue emitters have been reported
both in small molecular and polymer systems [2]. As com-
pared to green OLEDs, blue and red OLEDs have to be
improved in terms of color purity and efficiency [3]. Mean-
while, blue-emitting materials have still received consider-
able attention not only as a blue light source but also as a
On the other hand, the introduction of a flexible spacer
such as SiMe2 between well-defined chromophores in a
mononuclear compound [7] or a polymer chain [8] is cur-
rent topic in luminescent materials. One advantage is that
it facilitates the intramolecular photoinduced charge
*
Corresponding authors. Tel.: +82 41 860 1337; fax: +82 41 867 5396.
E-mail address: jko@korea.ac.kr (J. Ko).
0022-328X/$ - see front matter Ó 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.01.016

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T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
1
transfer process [9]. The other is that the silicon-based tet-
rahedral spacers could interrupt the p-conjugated chains,
resulting in tuning the color of emitting materials by con-
trolling conjugation length [8]. Recently, Luh et al. [10]
reported that the intrachain chromophore interaction due
to folding of copolymer has been observed in silylene–
divinylene copolymers. We also reported various silylene-
spaced divinyl- and trivinylarene fluorescent dyes [11]. To
our knowledge, the introduction of SiMe2 flexible spacer
into diphenylanthracene derivatives has not reported yet.
Only a few papers described 9,10-disilylanthracenes and
their synthesis, structure, optical and electronic properties
[12]. Especially, we chose pyrene and 9-phenylcarbazole
units as energy matching substituents so that their absorp-
tion maxima can overlap with the emission of diphenylan-
thracene for facilitating intramolecular energy transfer
[10b]. Moreover, we expected that the designed compound,
in which carbazole moiety as a pendent group, which let
the fabrication of OLEDs to be simplified by dual function
(emitting and hole-transporting). A tert-butyl group is
incorporated in the anthracene moiety not only to mini-
mize aggregation of planar anthracene segments but also
improve the solubility of the compounds in common sol-
vents [4].
for 3–4 support the proposed structures. The H NMR
spectrum of 3 reveals the formation of silane viewed from
the septet of Si–H of 4.59 ppm and doublet of SiMe2 at
0.49 ppm (3JHH = 3.9 Hz). The 29Si NMR spectrum of 3
shows a singlet at ꢀ23.5 ppm. This value is comparable
to that observed for the 9,10-disilylanthracene [14]. Hydro-
gen–chlorine exchange of the disilyldiphenylanthracenes in
the presence of a catalytic amount of palladium dichloride
in carbon tetrachloride was accomplished by the similar
method reported by Ishikawa and co-workers [15]. These
exchange reaction gave moisture sensitive yellow com-
pounds 5–6 in quantitative yield (Scheme 1). The chlori-
nated products 5–6 were readily isolated by extraction
with toluene. But the hydrolytic lability of the Si–Cl bond
precluded their isolation using chromatography.
Spectroscopic data for 5–6 are completely consistent
with their proposed structures. A parent ion in the mass
spectrum of 5 was observed at m/z 514. The 29Si NMR
spectra of 5–6 exhibited one resonance at 15.2 ppm, signif-
icantly downfield shifted than those of their silane com-
pounds 3–4.
Many metal complexes were found to be efficient cata-
lysts for the stereo-selective hydrosilylation of ethynyl
derivatives. Among the metal catalysts, the rhodium cata-
lyst exhibited the highest activity, completing the hydro-
silylation under mild condition. The Rh-catalyzed
hydrosilylation of hydrosilanes 3–4 with 1-ethynylpyrene
and 1-carbazolyl-4-ethynylbenzene afforded the 9,10-disub-
stituted (E)-divinylsilyldiphenylanthracene products 7–10
in moderate yields (Scheme 2). These efficient regio- and
stereo-selective polyaddition methods were developed by
Mori et al. [16].
In this paper, we describe: (i) the synthesis and charac-
terization of a blue emitting silylene-spaced diphenylan-
thracene derivatives; (ii) the optical properties of novel
bis{[(aryl)dimethylsilyl]phenyl}-anthracene; and (iii) the
electroluminescent properties of copolymer containing
bis[(dimethylsilyl)phenyl]anthracene and divinylbenzene.
2. Results and discussion
The trans configuration was readily assigned by the
characteristic signals of the 1H NMR spectra at 7.2–
6.7 ppm with a large coupling constant of the vinyl group
(J = 18.9–19.2 Hz). The absence of peaks at about
6.5 ppm with small coupling constant (J ꢁ 15 Hz) indicates
that no cis-vinylene bonds were formed. The 29Si NMR
spectra of 7–10 showed one resonance at ꢀ15.2 to
ꢀ16.6 ppm arising from the equivalent silicon atoms. Other
synthetic utility of the hydrosilylation products was dem-
onstrated by transformation of the representative products
5–6. Treatment of chlorosilanes 5–6 with 1-carbazolyl-4-
lithiobenzene and 1-lithiopyrene in THF afforded the
9,10-disubstituted disilyldiphenylanthracene compounds
11–14 which were stable enough to be isolated by silica
gel chromatography (Scheme 3).
2.1. Synthesis
Scheme 1 illustrates the synthetic procedures for the
preparation of bis[4-(di-methylsilyl)phenyl]anthracene 3–4
and bis[4-(chlorodimethylsilyl)phenyl]anthracene 5–6 deri-
vatives. Dibromodiphenylanthracene starting materials 1–
2 were synthesized by already known reduction procedure
developed by Smet et al. [13] from anthraquinone and 2-
tert-butylanthraquinone, respectively [4]. Thus, lithiation
of dibromoanthracene with n-BuLi at ꢀ78 °C in THF fol-
lowed by treatment with chlorodimethylsilane gave stable
bis[4-(dimethylsilyl)phenyl]anthracene 3–4 in high yields.
Compounds 3–4 are soluble in toluene and THF. The
1H, 13C, and 29Si NMR spectra, and mass spectroscopy
2 n-BuLi
Cl
Si
H
Si
2 SiMe2HCl
PdCl2
CCl4
Br
Br
Si
Si
H
THF
Cl
R
R
R
R = H (3), t-Bu (4)
R = H (1), t-Bu (2)
R = H (5), t-Bu (6)
Scheme 1.

T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
1889
N
(i)
Si
Si
R
N
R = H (7), t-Bu (8)
H
Si
Si
H
R
R = H (3), t-Bu (4)
(ii)
Si
Si
R
R = H (9), t-Bu (10)
Scheme 2. Reaction conditions: (i) 2 equiv of 1-carbazolyl-4-ethynylbenzene, RhCl(PPh3)3, NaI, THF, reflux, 12 h; (ii) 2 equiv of 1-ethynylpyrene,
RhCl(PPh3)3, NaI, THF, reflux, 12 h.
N
(i)
Si
Si
R
N
Cl
Si
R = H (11), t-Bu (12)
Si
Cl
R
R = H (5), t-Bu (6)
(ii)
Si
Si
R
R = H (13), t-Bu (14)
Scheme 3. Reaction conditions: (i) 2 equiv of 1-carbazolyl-4-lithiobenzene in THF; (ii) 2 equiv of 1-lithiopyrene in THF.

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T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
Incorporation of a tert-butyl group in the anthracene
15 reveals characteristic two doublets at 7.06 and
6.74 ppm with a large coupling constant (J = 18.6 Hz)
due to an inequivalent vinylic hydrogens, while the copoly-
mer 15 shows no resonance attributed to the Si–H. The 29Si
NMR spectrum of 15 reveals a singlet resonance at
ꢀ15.8 ppm, in accord with the upfield shift for the silylene-
vinylene-bridge system which appears in the region from
ꢀ12 to ꢀ30 ppm [17]. Such silylene-spaced vinylarene
copolymers were recently reported by Mori et al. [16a]
and Neckers and co-workers [18].
moiety dramatically improved the solubility of the com-
pounds in common solvents. These new fluorophores have
been fully characterized by NMR, mass, and elemental
analysis. The 13C NMR spectrum of 11 showed expected
18 resonances at 140.9–110.2 ppm due to the aromatic car-
bons. The 29Si NMR spectrum of 11 showed one resonance
at ꢀ10.7 ppm arising from the equivalent silicon atoms.
The new fluorophore 11 also exhibits a molecular ion peak
at m/z 928 in the mass spectrum.
We extended the hydrosilylation methodology to the
reaction of 2-tert-butyl-9,10-bis[4-(dimethylsilyl)phenyl]-
anthracene (4)to obtain copolymer. As expected, the
rhodium-catalyzed hydrosilylation of 4 with 1,4-diethynyl-
benzene yielded copolymer 15 in 88% yield (Scheme 4). The
purification process was that the polymer was dissolved in
small amount of chloroform and precipitated in excess
methanol several times.
2.2. Optical properties
The UV–Vis absorption and photoluminescence spectra
of all new compounds were obtained in CH2Cl2, with the
kmax values collected in Table 1. The absorption spectra
and emission spectra of selective compounds 3, 7, 11, 15,
and diphenylanthracene (dpa) are shown in Figs. 1 and 2,
respectively. Intense absorption bands with a fine structure
appear in the region of 250–420 nm. Three absorption
maxima peaks at ca. 350–400 nm indicate the characteristic
vibronic pattern attributed to the p ! p* electronic transi-
tions of diphenylanthracene and all the values are similar
to that of diphenylanthracene. The absorption maxima of
The molecular weight (Mw) and the polydispersity of the
polymer, determined by gel permeation chromatography
(GPC) using THF as eluent and polystyrene as calibration
standard, was in the range 200000 g/mol and 1.29, respec-
tively. The polymer was soluble in common solvents such
1
as THF, CHCl3, and benzene. The H NMR spectrum of
RhCl(PPh3)3
NaI
H
Si
Si
H
+
THF, reflux
4
Si
Si
n
15
Scheme 4.
Table 1
Physical data for the compounds 7–15 and dpa
UVa kmax (nm)
PLa kmax (nm)
PL in film kmax (nm)
Ufb
HOMOc (eV)
LUMO (eV)
Eg (eV)
d
Compound
7
8
328, 342, 358, 376, 397
294, 322, 358, 377, 399
290, 332, 357, 377, 398
299, 328, 357, 376, 398
293, 325, 358, 377, 397
295, 324, 358, 376, 397
297, 338, 357, 376, 398
299, 335, 357, 377, 397
302, 374
419, 436
420, 433
429
427
420, 435
428
434
429
430, 445
411, 432
430
429
515
502
434
432
510
497
468
0.88
0.90
0.87
0.92
0.94
0.93
0.92
0.95
0.88
0.95
5.83
5.85
5.81
5.80
5.82
5.83
5.80
5.81
5.40
2.84
2.88
2.89
2.87
2.87
2.87
2.87
2.87
2.44
2.99
2.97
2.92
2.93
2.95
2.96
2.93
2.94
2.96
9
10
11
12
13
14
15
dpa
a
356, 375, 395
Measured in CH2Cl2 solution.
Determined by the dilution method.
Determined using a photoelectron spectrometer except compound 15 (the HOMO level of compound 15 was determined by CV data).
Calculated by optical band edge.
b
c
d

T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
1891
ents showed coincident emission wavelength with solution
PL. However, the compounds with pyrene substituents
were extremely bathochromic shifted (ꢂ70 nm) in solid
state resulted in strong p–p stacking ability. The maximum
for the solution and solid state photoluminescence of the
polymer 15 appear at 430 and 468 nm, respectively. The
red shift from that of the solution can be attributed either
to the difference in the energy transfer processes between
the film and the solution due to the presence of rotation
of the chromophore, or to the effect of packing and local
geometry of the polymers.
The PL quantum yield is relatively high, which is com-
parable to those of diphenylanthracene (Uf = 0.95) or
9,10-disilylanthracenes (Uf = 0.90–0.97) reported by Mat-
sumoto et al. [12a]. The highest occupied molecular orbital
(HOMO) and lowest unoccupied molecular orbital
(LUMO) of these silylene-spaced diphenylanthracene
derivatives 7–14 are listed in Table 1. The HOMO was
determined using a ultraviolet photoelectron spectrometer
and LUMO was calculated by the optical band gap esti-
mated from the onset wavelength (the lowest-energy
absorption edge) of the UV–Vis absorption spectrum
(Eg = 1240 nm/konset) [21]. The HOMO and LUMO energy
of these products are at ca. 5.80–5.85 and 2.84–2.89 eV,
respectively.
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
dpa
3
7
11
15
250
300
350
400
450
Wavelength (nm)
Fig. 1. The absorption spectra of dpa, 3, 7, 11, and 15 in CH2Cl2.
1.0
dpa
3
7
11
15
CP-TMS
0.8
0.6
0.4
0.2
0.0
-0.2
2.3. Electrochemistry
As shown in Fig. 3, the electrochemical characteristic of
polymer 15 was investigated by the cyclic voltammetry
(CV) method which was measured in THF containing
0.1 M tetrabutylammonium perchlorate (TBAP). Cyclic
voltammetry was employed to evaluate the ionization
potentials (i.e., hole-injection ability) and the redox stabil-
ity of our copolymer. The CV curve was referenced to an
Ag/AgCl reference electrode. The first oxidation potential
was used to determine HOMO energy level and used to
obtain LUMO energy level with the absorption band edge
300
350
400
450
500
550
600
Wavelength (nm)
Fig. 2. The emission spectra of dpa, 3, 7, 11, 15 and CP-TMS in CH2Cl2.
the longest wavelength are somewhat red-shifted (2–4 nm)
compared to that of diphenylanthracene.
Compounds 7–14 exhibit intense fluorescence emission
in the blue wavelength region in dichloromethane solution
and the emission maxima are summarized in Table 1. The
similar values of kem maxima to diphenylanthracene which
are in the range 420–430 nm indicate that the p-conjuga-
tion was effectively interrupted by the silicon spacer. The
same emission spectra are obtained irrespective of the
applied excited wavelengths, indicating that downhill relax-
ation to the lowest excited state is efficient [17]. There are
small hypsochromic shifts of compounds (8, 10, 12, and
14) incorporated tert-butyl in the anthracene moiety with
respect to their analogues because of minimizing aggrega-
tion of planar anthracene segments. No residual emission
spectra of pyrene [19] and 9-phenylcarbazole [20] substitu-
ents in the range of 350–400 nm, prove that their emission
maxima overlap with the absorption of diphenylanthracene
pursuing intramolecular energy transfer. In the case of
solid PL, the compounds with 9-phenylcarbazole substitu-
20
0
-20
-40
-60
-80
-100
-120
-140
-160
-180
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
E(V)
Fig. 3. CV characteristics of polymer 15.

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T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
800
a
1000
700
600
500
100
400
300
200
10
100
0
3
4
5
6
7
8
9
10
Voltage (V)
0.8
0.6
0.4
0.2
0.0
b
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
Voltage (V)
Fig. 4. (a) Current density and luminescence (brightness) vs. voltage and (b) current efficiency vs. voltage characteristics of the EL device with polymer 15.
from UV–Vis absorption spectra. These energy levels of
polymer 15 are shown in Table 1.
cence verse voltage (I–V–L) and current efficiency verse
voltage, respectively. Fig. 4(a) shows that the device with
polymer 15 as an emitting layer exhibits moderate turn-
on voltage of 4.7 V (defined as 1 cd/m2) and maximum
brightness of about 1000 cd/m2. The maximum current effi-
ciency of device is about 0.7 cd/A from Fig. 4(b).
In conclusion, we were easily able to introduce a flexible
silylene-space into blue emitting diphenylanthracene deriv-
atives using the rhodium catalyzed hydrosilylation and salt
elimination reaction. These novel compounds 3–15 exhibit
intense fluorescence emission in the blue wavelength
region. Electroluminescent devices based on copolymer
15 was fabricated and showed good EL characteristics.
Further study with 4 as blue emitting copolymer including
the rigid segment will be explored. Device optimizations
are under investigation.
2.4. Electroluminescent device
The electroluminescence (EL) device fabricated through
vapor-deposition using the small molecular diphenylan-
thracene derivatives 7–14 showed the recrystallization dur-
ing the device operation, which is a typical problem of an
organic molecular EL device. The device with diphenylan-
thracene was also known to have poor film-forming prop-
erty [22]. Therefore, a EL device based on a polymer
containing diphenylanthracene is expected to have good
device properties. The devices were prepared in configura-
tion of ITO/PEDOT (65 nm)/polymer 15 (50 nm)/BaF2
(2 nm)/Ca (50 nm)/Al (300 nm). Comparing the relative
HOMO (5.4 eV) and LUMO (2.4 eV) energy levels of the
emitting polymer 15 with other layer sequences, the energy
levels seem to be appropriate to show good EL character-
istics. The EL characteristics of the present OLED are
shown in Fig. 4(a) and (b) for current density and lumines-
3. Experimental
All experiments were performed under a nitrogen atmo-
sphere in a vacuum atmosphere drybox or by standard

T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
1893
schlenk techniques. THF and ether were distilled from
sodium benzophenone and carbon tetrachloride was dis-
[M+]. Anal. Calc. for C34H38Si2: C, 81.21; H, 7.62. Found:
C, 81.01; H, 7.51%.
1
tilled from P2O5. H, 13C NMR and 29Si NMR spectra
were recorded on a Varian Mercury 300 spectrometer.
The absorption and photoluminescence spectra were
recorded on a Perkin–Elmer Lambda 2S UV–Vis spectro-
photometer and a Perkin–Elmer LS fluorescence spectrom-
eter, respectively. The fluorescence quantum yields of
compounds 7–15 were determined relative to 9,10-diphe-
nylanthracene in CH2Cl2 at 298 K (Uf = 0.95) by the dilu-
tion method [23]. The quantum yields were calculated using
previously reported procedures [24]. Ultraviolet photoelec-
tron spectroscopy (UPS) was measured by means of an
AC-2 machine. All starting materials were purchased from
either Aldrich or Strem and used without further purifica-
tion. 1,4-Diethynylbenzene [25], 1-ethynylpyrene [26],
1-carbazolyl-4-bromobenzene [27], 1-carbazolyl-4-ethynyl-
benzene [28], RhCl(PPh3)3 [29], 9,10-bis(4-bromo-phe-
nyl)anthracene (1), and 2-tert-butyl-9,10-bis(4-bromophe-
nyl)anthracene (2) [4] were prepared according to the
literature.
3.3. 9,10-Bis[4-(chlorodimethylsilyl)phenyl]anthracene (5)
To a shlenk flask charged with 9,10-bis[4-(dimethylsi-
lyl)phenyl]anthracene (3) (0.55 g, 1.23 mmol) and a cata-
lytic amount of PdCl2 (0.011 g, 0.062 mmol) was added
distilled carbon tetrachloride (30 mL). The mixture was
refluxed for 1 h under an Ar atmosphere. After cooling,
the solution was evaporated and the toluene was added.
The suspension was formed. The solution was filtered
through well-dried celite pad and drying under reduced
pressure affored the moisture sensitive pale yellow solid
1
in 81% yield. H NMR (C6D6): d 7.82 (d, 4H, J = 6.9 Hz,
Ph), 7.68 (dd, 4H, J = 7.2, J = 3.3 Hz, anth), 7.43 (d, 4H,
J = 6.9 Hz, Ph), 7.11 (dd, 4H, J = 7.2 Hz, J = 3.3 Hz,
anth), 0.56 (s, 12H, Si–CH3). 13C{1H} NMR (C6D6): d
141.8, 137.3, 135.6, 133.7, 131.4, 130.4, 128.9, 126.4, 2.1.
29Si{1H} NMR (CDCl3): d 15.2. MS: m/z 514 [M+]. Anal.
Calc. for C30H28Cl2Si2: C, 69.88; H, 5.47. Found: C, 69.65;
H, 5.35%.
3.1. 9,10-Bis[4-(dimethylsilyl)phenyl]anthracene (3)
3.4. 2-tert-Butyl-9,10-bis[4-(chlorodimethylsilyl)phenyl]-
anthracene (6)
To a stirred THF solution (30 mL) of 9,10-dibromodi-
phenylanthracene, 1 (1.65 g, 3.38 mmol) was added a solu-
tion of n-BuLi (5.0 mL, 1.6 M in hexane) at ꢀ78 °C and
stirred for 30 min at that temperature. To this solution
was added chlorodimethylsilane (0.9 mL, 8.11 mmol) at
ꢀ78 °C. The reaction mixture was slowly warmed to ambi-
ent temperature and stirred for 12 h. The solvent was
removed under reduced pressure. H2O and CH2Cl2 were
added to the resulting mixture. Then the product was
extracted with CH2Cl2 (20 mL). After evaporation, the
compound 3 was isolated as a white solid in 92% yield.
M.p.: 91–93 °C. 1H NMR (CDCl3): d 7.78 (d, 4H,
J = 7.2 Hz, Ph), 7.70 (dd, 4H, J = 6.9 Hz, J = 3.3 Hz,
anth), 7.48 (d, 4H, J = 7.2 Hz, Ph), 7.32 (dd, 4H,
J = 6.9 Hz, J = 3.3 Hz, anth), 4.59 (sept, 2H, J = 3.9 Hz,
Si–H), 0.49 (d, 12H, J = 3.9 Hz, Si–CH3). 13C{1H} NMR
(CDCl3): d 140.1, 136.8, 134.2, 130.9, 129.9, 127.2, 125.5,
124.8, ꢀ3.5. 29Si{1H} NMR (CDCl3): d ꢀ23.5. MS: m/z
446 [M+]. Anal. Calc. for C30H30Si2: C, 80.66; H, 6.77.
Found: C, 80.48; H, 6.62%.
Compound 6 was prepared using the same procedure as
1
described for 5 in 77% yield. H NMR (CDCl3): d 7.87–
7.85 (m, 4H, Ph), 7.66–7.43 (m, 9H, Ph and anth), 7.32-
7.29 (m, 2H, anth), 1.26 (s, 9H, t-Bu), 0.83 (s, 12H, Si–
CH3). 13C{1H} NMR (CDCl3): d 147.3, 141.5, 140.5,
138.8, 137.0, 136.4, 135.3, 133.2, 130.9, 130.1, 129.9,
128.5, 127.9, 126.1, 124.9, 122.4, 35.0, 31.0, 1.8. 29Si{1H}
NMR (CDCl3): d 15.1. MS: m/z 570 [M+]. Anal. Calc.
for C34H36Cl2Si2: C, 71.43; H, 6.35. Found: C, 71.25; H,
6.22%.
3.5. 9,10-Bis{[4-(4-carbazolyl)phenylvinyldimethylsilyl]-
phenyl}anthracene (7)
To a mixture of 9,10-bis[4-(dimethylsilyl)phenyl]anthra-
cene (3) (0.45 g, 1.0 mmol), 1-carbazolyl-4-ethynylbenzene
(0.59 g, 2.2 mmol), RhCl(PPh3)3 (0.002 g, 0.1 mol%), and
NaI (0.015 g, 5 mol%) was added THF (25 mL). The mix-
ture was refluxed for 12 h under inert atmosphere. The
solution was dried in vacuo. Pure product 7 was isolated
by silica gel chromatography (eluent: methylene chloride/
hexane 1:3) as a white solid in 61% yield. M.p.: 221–
223 °C. 1H NMR (CDCl3): d 8.16 (d, 4H, J = 7.5 Hz,
Ph), 7.85 (d, 4H, J = 7.5 Hz, Ph), 7.79–7.72 (m, 8H, Ph
and anth), 7.59 (d, 4H, J = 7.5 Hz, Ph), 7.53 (d, 4H,
J = 7.5 Hz, Ph), 7.44–7.26 (m, 16H, Ph and anth), 7.20
(d, 2H, J = 19.2 Hz, Ph–CH@), 6.74 (d, 2H, J = 19.2 Hz,
Si–CH@), 0.63 (s, 12H, Si–CH3). 13C{1H} NMR (CDCl3):
d 140.9, 140.0, 137.6, 137.2, 134.0, 131.1, 130.7, 129.9,
128.1, 127.1, 126.4, 125.8, 125.5, 124.8, 123.6, 120.5,
120.3, 119.7, 110.9, 109.6, ꢀ2.2. 29Si{1H} NMR (CDCl3):
3.2. 2-tert-Butyl-9,10-bis[4-(dimethylsilyl)phenyl]-
anthracene (4)
Compound 4 was prepared using the same procedure as
described for 3 in 87% yield. M.p.: 85 °C. 1H NMR
(CDCl3): d 7.80–7.77 (m, 4H, Ph), 7.72–7.62 (m, 4H, anth),
7.51–7.44 (m, 5H, Ph and anth), 7.33–7.30 (m, 2H, anth),
4.61 (m, 2H, Si–H), 1.27 (s, 9H, t-Bu), 0.50 (m, 12H, Si–
CH3). 13C{1H} NMR (CDCl3): d 147.3, 140.2, 139.3,
136.9, 136.3, 134.2, 131.7, 130.9, 129.9, 129.6, 128.5,
127.2, 126.7, 125.3, 124.5, 121.6, 118.6, 117.8, 35.0, 31.0,
ꢀ3.6. 29Si{1H} NMR (CDCl3): d ꢀ23.3. MS: m/z 502

1894
T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
d ꢀ15.2. MS: m/z 980 [M+]. Anal. Calc. for C70H56N2Si2:
(d, 2H, J = 9.0 Hz, pyr), 8.36 (d, 2H, J = 7.8 Hz, pyr),
8.20–7.91 (m, 20H, pyr), 7.77 (dd, 4H, J = 6.9 Hz,
J = 3.3 Hz, anth), 7.56 (d, 4H, J = 7.8 Hz, Ph), 7.34 (dd,
4H, J = 6.9 Hz, J = 3.3 Hz, anth), 7.18 (d, 2H,
J = 18.9 Hz, Ph–CH@), 6.78 (d, 2H, J = 18.9 Hz, Si–
CH@), 1.27 (s, 9H, t-Bu), 0.73 (s, 12H, Si–CH3). 13C{1H}
NMR (CDCl3): d 151.0, 142.7, 140.7, 140.2, 139.6, 138.8,
137.5, 134.1, 134.0, 132.9, 132.0, 131.6, 131.3, 131.0,
129.9, 129.7, 129.2, 128.6, 128.2, 127.8, 127.6, 127.1,
126.8, 126.2, 125.6, 125.3, 125.1, 124.0, 122.8, 120.4,
118.2, 112.7, 34.9, 31.0, ꢀ2.4. 29Si{1H} NMR (CDCl3): d
ꢀ16.6. MS: m/z 954 [M+]. Anal. Calc. for C62H46Si2: C,
88.00; H, 6.12. Found: C, 87.78; H, 6.01%.
C, 85.67; H, 5.75. Found: C, 85.42; H, 5.61%.
3.6. 2-tert-Butyl-9,10-bis{[4-(4-carbazolyl)phenylvinyl-
dimethylsilyl]phenyl}anthracene (8)
Compound 8 was prepared using the same procedure as
described for 7 except 2-tert-butyl-9,10-bis[4-(dimethylsi-
lyl)phenyl]anthracene (4) was used instead of 9,10-bis[4-
(dimethylsilyl)phenyl]anthracene (3). The pure product 8
was isolated by silica gel chromatography (eluent: methy-
lene chloride/hexane 1:3) as a pale yellow solid in 65%
yield. M.p.: 194–195 °C. 1H NMR (CDCl3): d 8.15 (d,
4H, J = 7.5 Hz, Ph), 7.92–7.28 (m, 35H, Ph and anth),
7.19 (d, 2H, J = 19.2 Hz, Ph–CH@), 6.84 (d, 2H,
J = 19.2 Hz, Si–CH@), 1.26 (s, 9H, t-Bu), 0.62 (s, 12H,
Si–CH3). 13C{1H} NMR (CDCl3): d 148.1, 147.2, 140.7,
137.3, 136.9, 134.0, 131.1, 130.0, 129.6, 128.6, 127.4,
127.0, 126.4, 126.0, 125.1, 123.7, 122.8, 121.6, 120.8,
120.5, 118.8, 118.2, 116.4, 114.8, 112.6, 110.3, 35.1, 29.8,
ꢀ2.0. 29Si{1H} NMR (CDCl3): d ꢀ15.6. MS: m/z 1036
[M+]. Anal. Calc. for C74H64N2Si2: C, 85.67; H, 6.22.
Found: C, 85.42; H, 6.08%.
3.9. 9,10-Bis{[4-(4-carbazolyl)phenyldimethylsilyl]-
phenyl}anthracene (11)
To a stirred THF solution (25 mL) of 1-carbazolyl-4-
bromobenzene (0.69 g, 2.1 mmol) was added n-BuLi
(1.5 mL, 2.4 mmol, 1.6 M in hexane) at ꢀ78 °C. The solu-
tion was stirred for 30 min at that temperature and then
added 9,10-bis[4-(chlorodimethylsilyl)phenyl]anthracene
(5) (0.49 g, 0.95 mmol) dissolved in THF (10 mL) via can-
nula. The solution was slowly warmed to room tempera-
ture and stirred another 8 h. H2O and brine was added to
the solution and the product was extracted with CH2Cl2.
Pure 11 was isolated by silica gel chromatography (eluent:
methylene chloride/hexane 1:5) as a white solid in 45%
yield. M.p.: 205–206 °C. 1H NMR (CDCl3): d 8.16 (d,
4H, J = 7.2 Hz, Ph), 7.90 (d, 4H, J = 7.2 Hz, Ph), 7.85
(d, 4H, J = 7.2 Hz, Ph), 7.79–7.72 (m, 4H, anth), 7.65 (d,
4H, J = 7.2 Hz, Ph), 7.55–7.29 (m, 20H, Ph and anth),
0.78 (s, 12H, Si–CH3). 13C{1H} NMR (CDCl3): d 140.9,
140.2, 138.7, 137.7, 137.1, 136.9, 136.0, 134.2, 131.2,
130.9, 129.9, 127.2, 126.3, 125.7, 124.9, 123.6, 120.5,
110.2, ꢀ2.1. 29Si{1H} NMR (CDCl3): d ꢀ10.7. MS: m/z
928 [M+]. Anal. Calc. for C66H52N2Si2: C, 85.30; H, 5.64.
Found: C, 85.12; H, 5.55%.
3.7. 9,10-Bis{[4-(pyrenyl)vinyldimethylsilyl]phenyl}-
anthracene (9)
Compound 9 was prepared using the same procedure as
described for 7 except 1-ethynylpyrene was used instead of
1-carbazolyl-4-ethynylbenzene. Pure 9 was isolated by silica
gel chromatography (eluent: methylene chloride/hexane
1
1:3) as a white solid in 70% yield. M.p.: 237–238 °C. H
NMR (CDCl3): d 8.47 (d, 2H, J = 9.3 Hz, pyr), 8.37 (d,
2H, J = 8.1 Hz, pyr), 8.25–8.00 (m, 16H, pyr), 7.93 (d, 4H,
J = 7.8 Hz, Ph), 7.78 (dd, 4H, J = 6.9 Hz, J = 3.3 Hz, anth),
7.57 (d, 4H, J = 7.8 Hz, Ph), 7.36 (dd, 4H, J = 6.9 Hz,
J = 3.3 Hz, anth), 7.18 (d, 2H, J = 18.9 Hz, Ph–CH@),
7.84 (d, 2H, J = 18.9 Hz, Si–CH@), 0.72 (s, 12H, Si–CH3).
13C{1H} NMR (CDCl3): d 142.4, 140.1, 137.7, 137.2,
134.3, 133.0, 132.2, 131.6, 131.4, 131.3, 131.0, 130.0,
128.4, 128.2, 127.7, 127.5, 127.2, 126.1, 125.5, 125.3,
125.1, 124.7, 123.0, 122.2, 120.6, 118.4, 117.2, 112.6, ꢀ2.8.
29Si{1H} NMR (CDCl3): d ꢀ16.3. MS: m/z 898 [M+]. Anal.
Calc. for C66H50Si2: C, 88.15; H, 5.60. Found: C, 88.02; H,
5.51%.
3.10. 2-tert-Butyl-9,10-bis{[4-(4-carbazolyl)phenyl-
dimethylsilyl]phenyl}anthracene (12)
Compound 12 was prepared using the same procedure
as described for 11 except 2-tert-butyl-9,10-bis[4-(chloro-
dimethylsilyl)phenyl]anthracene (6) was used instead of
9,10-bis[4-(chlorodimethylsilyl)phenyl]anthracene (5). Pure
12 was isolated by silica gel chromatography (eluent: meth-
ylene chloride/hexane 1:5) as a pale yellow solid in 42%
yield. M.p.: 192–194 °C. 1H NMR (CDCl3): d 8.17 (d,
4H, J = 7.2 Hz, Ph), 7.92–7.28 (m, 35H, Ph and anth),
1.26 (s, 9H, t-Bu), 0.79 (s, 12H, Si–CH3). 13C{1H} NMR
(CDCl3): d 140.9, 140.2, 138.7, 137.7, 137.1, 136.9, 136.0,
134.2, 132.6, 131.2, 130.9, 130.5, 129.9, 128.2, 127.2,
126.3, 125.7, 124.9, 123.6, 122.6, 120.5, 119.6, 117.4,
110.2, 35.0, 30.9, ꢀ2.2. 29Si{1H} NMR (CDCl3): d ꢀ10.9.
MS: m/z 984 [M+]. Anal. Calc. for C70H60N2Si2: C,
85.32; H, 6.14. Found: C, 85.13; H, 6.03%.
3.8. 2-tert-Butyl-9,10-bis{[4-(pyrenyl)vinyldimethylsilyl]-
phenyl}anthracene (10)
Compound 10 was prepared using the same procedure
as described for 7 except 1-ethynylpyrene, and 2-tert-
butyl-9,10-bis[4-(dimethylsilyl)phenyl]anthracene (4) were
used instead of 1-carbazolyl-4-ethynylbenzene, and 9,10-
bis[4-(dimethylsilyl)phenyl]anthracene (3), respectively.
Pure 10 was isolated by silica gel chromatography (eluent:
methylene chloride/hexane 1:3) as a pale yellow solid in
1
72% yield. M.p.: 222–225 °C. H NMR (CDCl3): d 8.47

T. Lee et al. / Journal of Organometallic Chemistry 691 (2006) 1887–1896
1895
3.11. 9,10-Bis[4-(pyrenyldimethylsilyl)phenyl]anthracene
(13)
J = 3.3 Hz, anth), 7.06 (d, 1H, J = 18.6 Hz, Ph–CH@),
6.74 (d, 1H, J = 18.6 Hz, Si–CH@), 1.26 (s, 9H, t-Bu),
0.57 (s, 12H, Si–CH3). 13C{1H} NMR (CDCl3): d 147.4,
140.1, 138.2, 137.5, 137.3, 136.9, 136.7, 134.3, 133.0,
132.2, 131.6, 131.4, 131.3, 131.0, 130.1, 129.9, 129.6,
128.5, 127.0, 126.1, 125.5, 125.3, 125.1, 124.7, 123.0, 35.1,
31.0, ꢀ2.2. 29Si{1H} NMR (CDCl3): d ꢀ16.5. Mw =
200000, Mw/Mn = 1.29.
Compound 13 was prepared using the same procedure
as described for 11 except 1-bromopyrene was used instead
of 1-carbazolyl-4-bromobenzene. Pure 13 was isolated by
silica gel chromatography (eluent: methylene chloride/hex-
1
ane 1:5) as a white solid in 50% yield. M.p.: 207 °C. H
NMR (CDCl3): d 8.38–7.99 (m, 18H, pyr), 7.82 (d, 4H,
J = 8.1 Hz, Ph), 7.72 (dd, 4H, J = 6.9 Hz, J = 3.3 Hz,
anth), 7.46 (d, 4H, J = 8.1 Hz, Ph), 7.33 (dd, 4H,
J = 6.9 Hz, J = 3.3 Hz, anth), 0.98 (s, 12H, Si–CH3).
13C{1H} NMR (CDCl3): d 147.0, 140.7, 140.0, 138.1,
136.9, 136.6, 136.1, 134.7, 134.1, 133.4, 133.2, 132.6,
131.4, 130.8, 130.0, 129.6, 128.5, 128.2, 127.6, 127.2,
126.0, 125.5, 125.0, 124.1, ꢀ0.5. 29Si{1H} NMR (CDCl3):
d ꢀ12.7. MS: m/z 846 [M+]. Anal. Calc. for C62H46Si2:
C, 87.90; H, 5.47. Found: C, 87.72; H, 5.36%.
3.14. CV measurements
The cyclic voltammetry experiment of polymer 15 was
performed with a BAS-100 electrochemical analyzer. All
measurements were carried out using a glassy carbon work-
ing electrode, a platinum auxiliary electrode and a non-
aqueous Ag/AgNO3 reference electrode. All experiments
were performed at room temperature using 0.1 M tetrabu-
tylammonium hexaflurophosphate (TPAP) as supporting
electrolyte and THF as solvent.
3.12. 2-tert-Butyl-9,10-bis[4-(pyrenyldimethylsilyl)phenyl]-
anthracene (14)
3.15. Fabrication of electroluminescent devices
Compound 14 was prepared using the same procedure as
described for 11 except 1-bromopyrene, and 2-tert-butyl-
9,10-bis[4-(chlorodimethylsilyl)phenyl]anthracene (6) were
used instead of 1-carbazolyl-4-bromobenzene, and 9,10-
bis[4-(chlorodimethylsilyl)phenyl]anthracene (5), respec-
tively. Pure 14 was isolated by silica gel chromatography
(eluent: methylene chloride/hexane 1:5) as a pale yellow solid
in 46% yield. M.p.: 198 °C. 1H NMR (CDCl3): d 8.47 (d, 2H,
J = 9.3 Hz, pyr), 8.37 (d, 2H, J = 8.1 Hz, pyr), 8.25–8.00 (m,
15H, pyr), 7.93 (d, 4H, J = 7.8 Hz, Ph), 7.78 (dd, 4H,
J = 6.9 Hz, J = 3.3 Hz, anth), 7.57 (d, 4H, J = 7.8 Hz, Ph),
7.36 (dd, 4H, J = 6.9 Hz, J = 3.3 Hz, anth), 1.29 (s, 9H, t-
Bu), 1.00 (s, 12H, Si–CH3). 13C{1H} NMR (CDCl3): d
147.3, 140.2, 140.0, 138.1, 136.9, 136.6, 136.1, 134.7, 134.1,
133.4, 133.2, 132.6, 132.2, 131.4, 130.8, 130.4, 130.0, 129.6,
129.2, 128.5, 128.2, 127.6, 127.2, 126.0, 125.5, 125.0, 124.1,
123.6, 123.0, 118.6, 35.1, 30.8, ꢀ0.2. 29Si{1H} NMR
(CDCl3): d ꢀ12.8. MS: m/z 902 [M+]. Anal. Calc. for
C66H54Si2: C, 87.76; H, 6.03. Found: C, 87.58; H, 5.92%.
The ITO electrode was cleaned by sonication in a deter-
gent solution for 4 min and washed with distilled water.
Further sonication in 1,1,1-trichloroethane for 3 min was
done before blowing dry under nitrogen. The devices were
prepared as a sequence of ITO/PEDOT (65 nm)/EML
(50 nm)/BaF2 (2 nm)/Ca (50 nm)/Al (300 nm). The hole
transporting material, poly(3,4-ethylene dioxythiophene)–
poly(styrene sulfonic acid) (PEDOT, Baytron-P), was pur-
chased from Bayer. PEDOT was first spin coated onto a
pre-cleaned ITO glass and baked at 110 °C for 10 min. A
solution of polymer 15 in toluene as an emission layer
(EML) was spin-coated onto the surface of PEDOT. This
film was baked at 130 °C for 1 h for removing the solvent.
The BaF2/Ca/Al cathode was deposited on the emitting
polymer by thermal evaporation with a metal mask. The
luminescence–voltage (L–V), current–voltage (I–V) and
current efficiency–voltage characteristics were measured
using a Keithley 238 source measurement unit and PR650
(Photo Research Corp.).
Acknowledgment
3.13. Polymer 15
This work was financially supported by KOSEF (R01-
2001-000053-0).
To a mixture of 2-tert-butyl-9,10-bis[4-(dimethylsilyl)-
phenyl]anthracene (4) (0.55 g, 1.1 mmol) and 1,4-diethynyl-
benzene (0.14 g, 1.1 mmol) was combined with
RhCl(PPh3)3 (0.002 g, 0.1 mol%), and NaI (0.015 g,
5 mol%) in THF (5 mL). The mixture was refluxed for
8 h under inert atmosphere. After evaporation, the poly-
merization mixture was dissolved in 5 mL of chloroform
and the solution was poured into a large amount of meth-
anol with vigorous stirring to form a precipitate. It was fil-
tered with a glass frit, washing one more time with
methanol, and dried under reduced pressure afforded the
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.jorganchem.
2006.01.016.
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