Efficient deep-blue emitters comprised of an anthracene core and terminal bifunctional groups for nondoped electroluminescence

Article abstract of DOI:10.1039/c1jm10465a

Four blue fluorescent host emitters with bifunctional charge transport groups appended to the 9- and 10-positions of the anthracene core have been designed and synthesized. By introducing peripheral bulky aryl-substitution groups to the emissive core, the

Full text of DOI:10.1039/c1jm10465a

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PAPER
Efficient deep-blue emitters comprised of an anthracene core and terminal
bifunctional groups for nondoped electroluminescence†
a
b
a
a
a
b
Minrong Zhu, Qiang Wang, Yu Gu, Xiaosong Cao, Cheng Zhong, Dongge Ma, Jingui Qina
*
a
*
and Chuluo Yang
Received 29th January 2011, Accepted 28th February 2011
DOI: 10.1039/c1jm10465a
Four blue fluorescent host emitters with bifunctional charge transport groups appended to the 9- and
10-positions of the anthracene core have been designed and synthesized. By introducing peripheral
bulky aryl-substitution groups to the emissive core, the four compounds show a decreased tendency to
ꢀ
crystallise and have high glass transition temperatures ranging from 154 to 226 C. The theoretical
calculations reveal that the four self-hosted blue emitters possess noncoplanar structures to suppress
intermolecular interaction within the films. The amorphous compounds exhibit strong deep-blue
emission both in solution and the solid state. With different end-capping groups, the photophysical and
electrochemical properties are tuned to produce efficient deep-blue performance with a simple device
architecture. Organic light-emitting diodes (OLEDs) featuring 4 as the emitter achieve a maximum
power efficiency of 2.0 lm Wꢁ1 with Commission Internationale de l’Eclairage (CIE) coordinates of
(0.16, 0.10) that are very close to the National Television Standards Committee’s blue standard. The
well-matched energy level between the anode and 4 as well as the intrinsic good charge transport
abilities results in a very low driving voltage (2.7 V), making the nondoped deep-blue
electroluminescent device power efficient.
emitting devices is often inferior to that of their red and green
Introduction
counterparts.
Organic light-emitting diodes (OLEDs) have attracted consid-
erable scientific and commercial attention since the pioneering
work by Tang et al. in 1987.1 Extensive research has been carried
out to promote OLEDs in such commercial application as flat-
panel displays and solid-state lighting resources.2,3 Full-color
displays require red, green, and blue emission of relatively equal
stability, efficiency, and color purity. It is critical to develop high
performance blue emission, which is defined as having
a Commission Internationale de l’Eclairage (CIE) y-coordinate
value < 0.15, because such an emitter can not only effectively
reduce the power consumption of a full-color OLED but can also
be utilized to generate light of other colors by energy cascade to
lower energy fluorescent or phosphorescent dopants.4–6 Since the
intrinsic wide band gap of blue-emitting materials makes it hard
to inject charges into emitters, the performance of blue light
High performance OLEDs are generally constructed in
a multilayer configuration with both hole- and electron-trans-
porting layers adjacent to the emission layer to balance electron–
hole recombination.7,8 But the use of complicated structures
increases the cost of device fabrication and hamper the mass
production of OLEDs. To achieve high efficiency along with
simple device configuration, functional materials with bipolar
characteristics have been designed and synthesized to achieve
good charge-transporting and charge-balancing properties.9–11
Thus, the devices can be simplified to single- or double-layer
structures while still retaining high efficiency, which would help
reduce the overall cost and increase the extent of OLED
commercialization.
Anthracene derivatives possessing excellent photo-
luminescence (PL) and electroluminescence (EL) properties have
been studied intensively to develop efficient blue-emitting mate-
rials.12–19 Among them, 9,10-diphenylanthracene (DPA) is an
attractive material for its unity fluorescence quantum efficiency
in dilute solution.20 Unfortunately, DPA tends to crystallize in
the solid state making it incapable of providing a homogeneous
film in device fabrication, resulting in grain boundaries or pin
holes that lead to current leakage. A serious drawback, as
exemplified by DPA and its derivatives, is that their fluorescence
in the solid state can be easily quenched. Generally, amorphous
aDepartment of Chemistry, Hubei Key Lab on Organic and Polymeric
Optoelectronic Materials, Wuhan University, Wuhan, 430072, People’s
Republic of China. E-mail: clyang@whu.edu.cn
bState Key Laboratory of Polymer Physics and Chemistry, Changchun
Institute of Applied Chemistry, Chinese Academy of Sciences,
Changchun, 130022, People’s Republic of China. E-mail: mdg1014@ciac.
jl.cn
† Electronic supplementary information (ESI) available: cyclic
voltammetry scans of the four compounds and synthesis details of the
precursors. See DOI: 10.1039/c1jm10465a
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thin films in OLEDs having high glass transition temperatures,
are less vulnerable to heat and, hence, their device performance is
more stable.
coupling reaction of the boronic ester and the dibromide 8 or 9
yielded the final products 1–4.
The key precursors—oxadiazole-containing arylbromide and
arylboronic ester—were fully characterized by 1H NMR, 13C
NMR, mass spectrometry, and elemental analysis; 1–4 were
In this study, we prepared a series of anthracence derivatives
appended with bifunctional groups for use as blue emitters in
OLEDs. Direct substitution of either a strong electron with-
drawing or electron donating groups at the 9- and 10-positions
would change the electron density on the anthracene ring, and
thereby the color purity of the blue emission might be impaired.21
Our strategy to overcome the problem is introducing phenyl
group by meta linkage as a space block between the anthracene
core and electron-transporting oxadiazole moiety.22 Thus, the
large band gaps are retained to ensure that the emissions are still
located in the deep blue region. Electron-rich units such as
carbazole, triphenylamine are attached to the above electron-
deficient oxadiazole units to enhance the hole-tranport and -
injection abilities. All these compounds show high fluorescence
quantum yields in solution when using DPA as the standard. The
steric hindrance imparted by peripheral bulky aryl substituents
greatly improved their thermal stabilities. We fabricated simple
double-layer devices that achieved efficient deep-blue perfor-
mance of 1.7 cd Aꢁ1 (ꢂ 2.0 lm Wꢁ1) with CIE coordinates of
(0.16, 0.10).
1
characterized by H NMR, MALDI-TOF and elemental anal-
ysis; their 13C NMR spectra were not available because of their
poor solubility in common organic solvents.
Photophysical properties
The UV-vis absorption in toluene solution and the PL spectra of
1–4 recorded both in toluene solution and the film state are
presented Fig. 1. We assign the absorption bands in the region
from 290 to 320 nm to the n–p* transition of the peripheral
functional aryl groups.23 For 1 and 2 with a meta linkage between
electron-rich units of carbazole/triphenylamine and the electron-
deficient oxadiazole unit, the similar characteristic vibronic
patterns in the range from 350 to 400 nm can be attributed to the
p–p* transitions of the anthracene core.24 Whereas, for 3 and 4
with para linkages between triphenylamine and oxadiazole,
the intramolecular charge transfer is enhanced owing to the good
p-conjugation.25 Thus, the contributions of the p–p* transitions
of the anthracene core are overwhelmed with the p–p* transition
from the donors to the acceptors.
Results and discussion
The compounds are highly emissive in toluene solution with
the emission maxima being closely grouped and falling in the
Scheme 1 illustrates the synthesis and structures of new anthra-
cene-based bifunctional molecules 1–4. The relatively high yields
and simple workup procedures render the tetrazole route an
attractive prospect for the preparation of oxadiazole-containing
peripheral moieties. The oxadiazole-containing arylbromide
intermediates 5b, 6b and 7b were facilely prepared via the tetra-
zole route, which in turn underwent cross-coupling with the
pinacol ester of diboron to give the oxadiazole-containing
boronic esters 5, 6, and 7 (for details, see ESI†). The suzuki
Scheme 1 Synthetic routes to 1–4. Reagents and conditions: i) Pd
(PPh3)4, 2 M Na2CO3, THF, 85 ꢀC, 48 h.
Fig. 1 a) UV–vis absorption and PL spectra of 1–4 in toluene solution.
b) PL spectra in film.
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deep-blue region (430–433 nm). The PL spectra of these
compounds in the solid state show slight a bathochromic shift
(ꢂ15 nm) with respect to those of the solution, implying that the
intermolecular interactions do not occur in the ground state.26
Besides this, the full widths at half maximum (FWHM) are
almost the same both in solution and the film. It appears that the
aryl substituents at the 9- and 10-positions of the anthracene
prevented close molecular packing in the solid state and effec-
tively inhibited excimer formation as well as fluorescence
quenching.27 These materials show high fluorescence quantum
yield (0.52–0.89) in dilute toluene solution when using DPA
(F ¼ 0.90) as the calibration standard.
the 9,10-diphenylanthracene core. But for 4, the electron density
distribution of the HOMO and LUMO orbitals are localized
predominantly on the anthracene chromophore.30 It seems that
the electron densities of the anthracene core are isolated from the
peripheral groups with two bulky tert-butyl substituted at 2- and
6- positions of anthracene ring.
Cyclic voltammetry (CV) was carried out to identify the elec-
trochemical behaviors of these materials. In each case, the anodic
scan was performed in CH2Cl2, while the cathodic scan was
conducted in THF. The highest occupied molecular orbital
(HOMO)/lowest occupied molecular orbital (LUMO) energy
levels were estimated from the onset of oxidation/reduction
potentials as summarized in Table 1. 2 and 3 with triphenylamine
peripheral groups have relative higher HOMO levels than 1 with
the carbazole peripheral group. Nevertheless, the HOMO level
for 4 (5.27 eV) is obviously higher than those of other anthracene
derivatives (ꢂ5.60 eV) previously reported.15,31,32 It could be
rationalized that the two tert-butyl substituents might reduced
the oxidation potentials of the anthracene unit and raise the
HOMO energy levels.33 The well-matched energy levels between
2, 3, 4 and the anode will facilitate charge injection into the
emission layer contributing to the low driving voltage.
Thermal properties
We investigated the thermal properties of the new compounds
using differential scanning calorimetry (DSC) and thermogravi-
metric analysis (TGA). The four compounds exhibit high
thermal-decomposition temperatures (Td, corresponding to 5%
weight loss) in the range of 466–474 ꢀC. Their glass transition
temperature (Tg) values range from 154 to 226 ꢀC, which are
much higher than those of common blue fluorescent materials,
such as 4,40-bis(2,2-diphenylvinyl)biphenyl (DPVBi) (64 ꢀC) and
2-methyl-9,10-di(2-naphthyl)-anthracene (MADN) (120 ꢀC).28,29
1 shows the highest Tg value as it has the largest molecular size,
molecular weight and due to the more rigid nature of carbazole
units. The excellent thermal stability with high Td and Tg values
enables the preparation of homogeneous and stable amorphous
thin films by vacuum deposition, which is basic requirement for
the operation of OLEDs.
Electroluminescence properties
To evaluate EL performances of 1–4 as nondoped blue emitters,
we fabricated 4 versions of device I with typical double-layer
configuration as follows: ITO/emitting layer (EML, 70 nm)/
1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBI, 30 nm)/
LiF (1 nm)/Al (120 nm). TPBI and LiF act as the electron-
transporting layer (ETL) and electron-injecting layer (EIL),
respectively.
Theoretical calculations and electrochemical properties
All the devices exhibit pure blue emission with peak maxima at
440–450 nm. Fig. 3 shows the EL spectra, current density–
voltage–brightness (J–V–L) characteristics, and efficiency versus
current density curves of the devices, and Table 2 summarizes the
EL data. The EL spectra of 1–3 show larger FWHMs than those
of the PL spectra. This may arise from the formation of an
excimer or exciplex during the operation of the device . In
contrast, the EL spectrum of 4 is similar to its PL spectrum,
which indicates that the excimer or exciplex have been effectively
suppressed during the EL process. The driving voltage decreased
Density functional theory (DFT) calculations (B3LYP; def2-
SVP) were carried out to obtain information about the HOMO
and LUMO distributions of the compounds (Fig. 2). For 1, 2 and
3 which bear strong donors such as carbazole and triphenyl-
amine, the HOMO orbitals are mainly located on the electron-
donating groups, the LUMO orbitals are mainly distributed on
Table 1 Photophysical, electrochemical and thermal data of 1–4
1
2
3
4
Tg/Td (ꢀC)
labs (nm)a
226/471
375/395
415/431
436
54
52
154/475
308/376
433
433
58
56
0.52
5.38/2.48
173/466
362
430
447
55
46
0.67
5.32/2.24
180/474
360
433
445
53
54
0.89
5.27/2.36
lem, max (nm)a
l
em, max (nm)b
FWHMa
FWHMb
FFL
c
0.80
5.51/2.47
HOMO/LUMO
(eV)d
a
b
Measured in toluene. Measured in the film. Fluorescence quantum
c
yields in toluene solution, using 9,10-diphenyl-anthracence (F ¼ 0.9) as
d
standard. Determined from the onset of oxidation/reduction
a
potentials.
Fig. 2 Calculated spatial distributions of the HOMO and LUMO levels
of 1–4.
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To assess the charge transport abilities of the bipolar blue
emitter, we chose to fabricate two additional types of device with
compound 4: device II with the structure: ITO/1,4-bis[(1-naph-
thylphenyl)amino]biphenyl (NPB, 40 nm)/4 (30 nm)/TPBI
(30 nm)/LiF (1 nm)/Al (120 nm); and device III with the struc-
ture: ITO/NPB (40 nm)/4 (60 nm)/LiF (1 nm)/Al (120 nm). Fig. 4
shows EL spectra at 7 V, efficiency versus current density curves
and the J–V–L characteristics of the devices (Table 3).
Device II had a trilayer structure in which 4 only functioned as
the emission layer; and NPB was incorporated as the hole-
transporting layer. The turn on voltage of device II (2.9 V) was
Fig. 3 a) EL spectra at applied voltage of 7 V. Inset: current efficiency
versus current density curves of the devices. b) J–V–L characteristics.
in the following order: 1 > 2 > 3 > 4, which coincides well with
the sequence of the HOMO levels. The very low turn-on voltage
for 4 (2.7 V) can be attributed to the low energy barrier between
ITO and the EML. The highest driving voltage for 1 can be
explained by it having the lowest HOMO energy level and elec-
trically insulating tert-butyl groups attached to carbazole units.
The power efficiencies and luminescence efficiencies vary in
accordance with the changes in the end-capping groups though
these compounds share the same emissive core. The EL perfor-
mance of 4 reached 1.7 cd Aꢁ1, 2.0 lm Wꢁ1 at a current density of
0.2 mA cmꢁ2, which are comparable with other anthracene-based
blue host emitters.34 We believe that sublimation of our
compounds and optimization of device structures should lead to
further improvement in device performance.
Fig. 4 a) EL spectra at applied voltage of 7V. Inset: current efficiency
versus current density curves of the device. b) J-V-L characteristics.
Device configurations: (I) ITO/4 (70 nm)/TPBI (30 nm)/LiF (1 nm)/Al
(120 nm); (II) ITO/NPB (40 nm)/4 (30 nm)/TPBI (30 nm)/LiF (1 nm)/Al
(120 nm); (III) ITO/NPB (40 nm)/4 (60 nm)/LiF (1 nm)/Al (120 nm).
Table 2 Electroluminescence characteristics of device I with 1–4 as the EML
ELa (nm)
FWHMa (nm)
Lmax (cd mꢁ2
)
hc.max (cd Aꢁ1
)
hp.max (lm Wꢁ1
)
CIEf (x, y)
b
Von (V)
c
d
e
EML
I
I
I
I
1
2
3
4
444
448
448
444
60
72
80
52
7.1
4.3
3.1
2.7
402
531
1833
3933
0.8
0.9
1.2
1.7
0.3
0.5
1.1
2.0
0.17, 0.12
0.18, 0.16
0.18, 0.20
0.16, 0.10
a
c
Recorded at 8 V. b Turn-on voltages at 1 cd mꢁ2
International de l’Eclairage coordinates.
.
Maximum luminance. d Maximum current efficiency. e Maximum power efficiency. f Commission
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slightly higher than that of device I (2.7 V). This can be attributed
to the lower HOMO energy of NPB (5.50 eV) compared to that
of 4 (5.27 eV). A maximum current efficiency of 1.6 cd Aꢁ1 and
a maximum power efficiency of 1.4 lm Wꢁ1 were achieved with
CIE coordinates of (0.16, 0.21). The efficiency and color purity
were inferior to those of device I utilizing 4 as hole-transporting
and emission layer. It can be assumed that the charge recombi-
nation zone formed near the interface of NPB and the emitting
layer, which may lead to the formation of an exciplex at the
interface for device II and harm the color purity. The results
suggest that 4 can play a better role in hole-injection and -
transporting than NPB.
ionization time-of-flight) mass spectra were performed on Bruker
BIFLEX III TOF mass spectrometer. UV-vis absorption spectra
were recorded on a Shimadzu UV-2500 recording spectropho-
tometer. Photoluminescence spectra were recorded on a Hitachi
F-4500 fluorescence spectrophotometer. Differential scanning
calorimetry (DSC) was performed on a NETZSCH DSC 200 PC
unitꢀat a heating rate of 10 C minꢁ1 from room temperature to
ꢀ
300 C under argon. The glass transition temperature (Tg) was
determined from the second heating scan. Thermogravimetric
analysis (TGA) was undertaken with a NETZSCH STA 449C
instrument. The thermal stability of the samples under a nitrogen
atmosphere was determꢀined by measuring their weight loss while
heating at a rate of 15 C minꢁ1 from 25 to 600 C. Cyclic vol-
ꢀ
By introducing electron-deficient oxadiazole unit to the emis-
sive core, the bipolar emitter 4 is expected to have an electron-
transporting ability. Hence, device III was fabricated with
a bilayer structure in which 4 played the role of the emission layer
and the electron-transporting layer. The device exhibited
a maximum current efficiency of 1.5 cd Aꢁ1 and maximum power
efficiency of 1.0 lm Wꢁ1 with CIE coordinates of (0.16, 0.18).
These values are comparable with that of device II, revealing
facile electron-transporting aptitude of 4. The results of device II
and III disclose the bipolar nature of these blue emitters.
tammetry (CV) was carried out in nitrogen-purged THF
(reduction scan) and dichloromethane (oxidation scan), respec-
tively, with a CHI voltammetric analyzer. Tetrabutylammonium
hexafluorophosphate (TBAPF6) (0.1 M) was used as the sup-
porting electrolyte. The conventional three-electrode configura-
tion consists of a platinum working electrode, a platinum wire
auxiliary electrode, and an Ag wire pseudo-reference electrode
with ferrocenium–ferrocene (Fc+/Fc) as the internal standard.
Cyclic voltammograms were obtained at scan rate of 100 mV sꢁ1
.
Formal potentials are calculated as the average of cyclic vol-
tammetric anodic and cathodic peaks. The onset potential was
determined from the intersection of two tangents drawn at the
rising and background current of the cyclic voltammogram.
Conclusion
We have designed and synthesized a series of anthracene deriv-
atives appended with different charge transport groups, aimed at
tuning the charge transport abilities while maintaining the
emission nature of anthracene core. The rational molecular
design endows the blue emitters with a noncoplanar conforma-
tion which results in their good thermal stability and pronounced
PL efficiency. Highly efficient deep-blue EL performance can be
realized in a simple bilayer structure, utilizing compound 4 as the
hole-injection, and -transporting as well as emission layer, with
a maximum power efficiency of 2.0 lm Wꢁ1 and CIE coordinates
of (0.16, 0.10) owing to the very low turn-on voltage. We believe
that our strategy for designing blue fluorescent host emitters can
be applied to generate more efficient deep-blue materials for use
in OLEDs display.
Computational details
The geometrical and electronic properties were performed with
the Turbomole 6.0 program package. The geometies was opti-
mized by means of the B3LYP (Becke three parameters hybrid
functional with Lee–Yang–Perdew correlation functionals) with
the def2-SVP atomic basis set. Molecular orbitals were visualized
using gOpenmol.
Device fabrication and measurement
The hole-transporting material NPB (1,4-bis(1-naph-
thylphenylamino)-biphenyl), and electron-transporting material
1,3,5-tris(N-phenylbenzimidazol-2-yl)benzene (TPBI) were
obtained from a commercial source. Commercial indium tin
oxide (ITO) coated glass with sheet resistance of 10 U/square was
used as the starting substrate. Before device fabrication, the ITO
glass substrates were pre-cleaned carefully and treated by oxygen
plasma for 2 min. Then the sample was transferred to the
deposition system. The devices were fabricated by evaporating
organic layers onto the ITO substrate sequentially with a pres-
sure better than 5 ꢃ 10ꢁ6 mbar. Finally, a cathode composed of
Experimental section
General information
1H NMR and 13C NMR spectra were measured on a MECUYR-
VX300 spectrometer. Elemental analyses of carbon, hydrogen,
and nitrogen were performed on a Vario EL III microanalyzer.
Mass spectra were measured on a ZAB 3F-HF mass spectro-
photometer. MALDI-TOF (matrix-assisted laser-desorption/
Table 3 Electroluminescence characteristics of devices I, II and III
CIEe (x, y)
a
Von (V)
b
c
d
Device type
NPB (nm)
4 (nm)
TPBI (nm)
Lmax (cd mꢁ2
)
hc.max (cd Aꢁ1
)
hp.max (lm Wꢁ1
)
I
II
III
-
40
40
70
30
60
30
30
-
2.7
2.9
2.9
3933
4766
2569
1.7
1.6
1.5
2.0
1.4
1.0
0.16, 0.10
0.16, 0.21
0.16, 0.18
a
b
c
Maximum luminance. Maximum current efficiency. Maximum power efficiency. Commission International de
d
e
Turn-on voltages at 1 cd mꢁ2
I’Eclairage coordinates.
.
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lithium fluoride (1 nm) and aluminium (100 nm) was sequentially
deposited onto the substrate in the vacuum of 10ꢁ6 Torr. The L–
V–J of the devices was measured with a Keithley 2400 Source
meter and a Keithley 2000 Source multimeter equipped with
a calibrated silicon photodiode. The EL spectra were measured
by JY SPEX CCD3000 spectrometer. All measurements were
carried out at room temperature under ambient conditions.
4,40-(5,50-(3,30-(2,6-di-tert-butylanthracene-9,10-diyl)bis (3,1-
phenylene))bis(1,3,4-oxadiazole-5,2-diyl))bis(N,N-di
phenyl
1
aniline) (4). 640 mg, white powder, yield: 75%. H NMR (300
MHz, CDCl3): d 8.37 (d, J ¼ 7.5 Hz, 2H), 8.23 (s, 2H), 7.92 (d,
J ¼ 8.7 Hz, 4H), 7.81 (t, J ¼ 7.5 Hz, 2H), 7.68 (d, J ¼ 8.4 Hz, 2H),
7.62 (s, 2H), 7.57 (s, 2H), 7.47 (d, J ¼ 6.3 Hz, 2H), 7.33–7.25 (m,
10H), 7.15–7.11 (m, 10H), 7.08 (d, J ¼ 8.4 Hz, 4H), 1.24 (s, 18H).
Anal. calcd for C74H60N6O2 (%): C 83.43, H 5.68, N 7.89; found:
C 82.92, H 5.96, N 7.69. MALDI-TOF: m/z 1065.1.
Preparation of the compounds
The synthesis details of the precursors 5, 6, and 7 are presented in
the ESI†. All solvents used in the reactions were purified
following routine procedures.
Acknowledgements
We thank the National Natural Science Foundation of China
(Nos. 90922020), the National Basic Research Program of
China (973 Program-2009CB623602, 2009CB930603), the Open
Research Fund of State Key Laboratory of Polymer Physics
and Chemistry, Changchun Institute of Applied Chemistry,
Chinese Academy of Sciences, and the Fundamental Research
Funds for the Central Universities of China for financial
support.
General procedure for the synthesis of the anthracene derivatives
Suzuki coupling of the arylboronic ester (5, 6 or 7) and dibromide
(9,10-dibromoanthracene 8 or 9,10-dibromo-2,6-di-tert-buty-
lanthracene 9) yielded the target compounds. Na2CO3 (2 M in
H2O, 8 ml, 16.0 mmol) was added to a solution of dibromide (0.8
mmol) and arylboronic ester (1.92 mmol) in 24 ml THF. The
mixture was degassed for half an hour and then Pd(PPh3)4 (0.032
mmol, 40 mg) was added under a flow of nitrogen. Then the flask
was heated to reflux under nitrogen atmosphere. The clear
solution became cloudy and a precipitate formed 2 h later. The
reaction mixture was allowed to reflux for another 36 h to
complete the conversion. After cooling to room temperature, the
resulting precipitate was collected by filtration, washed with
water and various kinds of hot organic solvents such as toluene,
THF, chloroform several times, and then dried under vacuum.
These final products were subjected to OLEDs fabrication
without further purification.
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12 K. Danel, T.-H. Huang, J. T. Lin, Y.-T. Tao and C.-H. Chuen, Chem.
Mater., 2002, 14, 3860.
9,10-Bis(3-(5-(3-(3,6-di-tert-butyl-9H-carbazol-9-yl) phenyl)-1,3,4-
oxadiazol-2yl)phenyl)anthracene (1). 656 mg, white powder, yield:
70%. 1H NMR (300 MHz, CDCl3): d 8.39 (d, J ¼ 9.0 Hz, 2H), 8.29
(s, 2H), 8.26 (d, J ¼ 7.8 Hz, 2H), 8.15–8.17 (m, 2H), 8.13–8.12
(m, 4H), 7.82 (t, J ¼ 7.8 Hz, 2H), 7.73–7.64 (m, 10H), 7.47–7.43 (m,
4H), 7.38–7.32 (m, 8H). 1.45 (s, 36H). Anal. calcd for C82H72N6O2
(%): C 83.93, H 6.18, N 7.16; found: C 83.57, H 6.56, N 7.08.
MALDI-TOF: m/z 1172.4.
13 W.-J. Shen, R. Dodda, C.-C. Wu, F.-I. Wu, T.-H. Liu, H.-H. Chen,
C. H. Chen and C.-F. Shu, Chem. Mater., 2004, 16, 930.
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Chem., 2008, 18, 3376.
16 P.-I. Shih, C.-Y. Chuang, C.-H. Chien, E. W.-G. Diau and C.-F. Shu,
Adv. Funct. Mater., 2007, 17, 3141.
17 Y. H. Kim, D. C. Shin, S.-H. Kim, C.-H. Ko, H.-S. Yu, Y.-S. Chae
and S. K. Kwon, Adv. Mater., 2001, 13, 1690.
3,30-(5,50-(3,30-(Anthracene-9,10-diyl)bis(3,1-phenylene))bis (1,3,4-
oxadiazole-5,2-diyl))bis(N,N-diphenylaniline) (2). 625 mg, white
powder, yield: 82%. 1H NMR (300 MHz, CDCl3): d 8.35 (d, J ¼ 7.5
Hz, 2H), 8.21 (s, 2H), 7.83 (s, 2H), 7.78 (t, J ¼ 7.8 Hz, 2H), 7.69 (d, J
¼ 9.0 Hz, 6H), 7.39–7.36 (m, 4H), 7.31–7.18 (m, 14H), 7.13 (m, 8H),
7.02 (t, J ¼ 7.2 Hz, 4H). Anal. calcd for C66H44N6O2 (%): C 83.17,
H 4.65, N 8.82; found: C 82.90, H 4.75, N 8.75. MALDI-TOF: m/z
953.3.
18 Y.-H. Kim, H.-C. Jeong, S.-H. Kim, K. Yang and S.-K. Kwon, Adv.
Funct. Mater., 2005, 15, 1799.
4,40-(5,50-(3,30-(Anthracene-9,10-diyl)bis(3,1-phenylene))bis (1,3,4-
oxadiazole-5,2-diyl))bis(N,N-diphenylaniline) (3). 610 mg, green
powder, yield: 80%. 1H NMR (300 MHz, CDCl3): d 8.56 (d, J ¼ 9.3
Hz, 2H), 8.40 (s, 2H), 8.09 (d, J ¼ 8.1 Hz, 4H), 7.96 (t, J ¼ 7.2 Hz,
2H), 7.90–7.86 (m, 4H), 7.60–7.57 (m, 4H), 7.48–7.43 (m, 14H), 7.33
(d, J ¼ 6.9 Hz, 8H), 7.25 (d, J ¼ 6.9 Hz, 4H). Anal. calcd for
C66H44N6O2 (%): C 83.17, H 4.65, N 8.82; found: C 83.64, H 4.41,
N 8.73. MALDI-TOF: m/z 953.3.
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