Synthesis and electroluminescence properties of highly efficient dual core chromophores with side groups for blue emission

Article abstract of DOI:10.1039/c4tc00075g

Highly efficient blue emitting materials consisting of dual core derivatives with phenyl and/or naphthyl side groups and asymmetric or symmetric structures were designed and synthesized. The asymmetric structures 1-naphthalen-1-yl-6-(10-phenyl-anthracen-9-yl)-pyrene (Ph-AP-Na) and 1-(10-naphthalen-1-yl-anthracen-9-yl)-6-phenyl-pyrene (Na-AP-Ph), and the symmetric structures 1-phenyl-6-(10-phenyl-anthracen-9-yl)-pyrene (Ph-AP-Ph) and 1-naphthalen-1-yl-6-(10-naphthalen-1-yl-anthracen-9-yl)-pyrene (Na-AP-Na) were synthesized. Of the synthesized compounds, Na-AP-Na was found to exhibit the highest EL device efficiency of 5.46 cd A^-1. Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na exhibit EL maximum values of real blue color in the range 455 nm to 463 nm. The y values of their color coordinates are within the range 0.125 to 0.142, so these compounds exhibit good blue color coordinates for displays. The lifetime of the Na-AP-Na device was more than three times longer than that of the AP dual core (1-anthracen-9-yl-pyrene) device. This journal is the Partner Organisations 2014.

Full text of DOI:10.1039/c4tc00075g

Journal of
Materials Chemistry C
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PAPER
Synthesis and electroluminescence properties of
highly efficient dual core chromophores with side
groups for blue emission†
Cite this: J. Mater. Chem. C, 2014, 2,
4737
Hayoon Lee,‡a Beomjin Kim,‡a Seungho Kim,a Joonghan Kim,a Jaehyun Lee,a
a
b
a
*
Hwangyu Shin, Ji-Hoon Lee and Jongwook Park
Highly efficient blue emitting materials consisting of dual core derivatives with phenyl and/or naphthyl side
groups and asymmetric or symmetric structures were designed and synthesized. The asymmetric structures
1-naphthalen-1-yl-6-(10-phenyl-anthracen-9-yl)-pyrene
(Ph-AP-Na) and
1-(10-naphthalen-1-yl-
anthracen-9-yl)-6-phenyl-pyrene (Na-AP-Ph), and the symmetric structures 1-phenyl-6-(10-phenyl-
anthracen-9-yl)-pyrene (Ph-AP-Ph) and 1-naphthalen-1-yl-6-(10-naphthalen-1-yl-anthracen-9-yl)-
pyrene (Na-AP-Na) were synthesized. Of the synthesized compounds, Na-AP-Na was found to exhibit
the highest EL device efficiency of 5.46 cd Aꢀ1. Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na exhibit
EL maximum values of real blue color in the range 455 nm to 463 nm. The y values of their color
coordinates are within the range 0.125 to 0.142, so these compounds exhibit good blue color
coordinates for displays. The lifetime of the Na-AP-Na device was more than three times longer than
that of the AP dual core (1-anthracen-9-yl-pyrene) device.
Received 13th January 2014
Accepted 22nd March 2014
DOI: 10.1039/c4tc00075g
www.rsc.org/MaterialsC
emitters with long device lifetimes because, with a wide band
gap, their electronic levels are likely to be mismatched with the
Introduction
highest occupied molecular orbital (HOMO) and lowest unoc-
cupied molecular orbital (LUMO) levels of the other OLED layers
such as the hole transporting layer (HTL) and the electron
transporting layer (ETL). These differences between the elec-
tronic levels result in a mismatched carrier balance of electrons
and holes, a low EL efficiency and a short lifetime.
Since the study of organic light-emitting diodes (OLEDs) began,
OLEDs have received much attention because of their potential
applications in full-color at panel displays and next generation
lighting.1–6 In order to fabricate full color OLED displays, we
need high performance red-light, green-light, and blue-light
emitters with high electroluminescence (EL) efficiencies, good
thermal properties, long device lifetimes, and pure color coor-
dinates.7–17 A red-light emitter with CIEx,y coordinates of (0.66,
0.34) and a long lifetime of more than 600 000 h (half life-
time@1000 cd mꢀ2) at 24 cd Aꢀ1 has recently been developed. A
green-light emitter with CIEx,y coordinates of (0.34, 0.62) and a
lifetime of 400 000 h (half lifetime@1000 cd mꢀ2) at 78 cd Aꢀ1
has also been achieved.18 However, the best official results for a
blue-light emitter with uorescence materials are a short life-
time of only 10 000 h at 9.0 cd Aꢀ1 and CIEx,y coordinates of
(0.14, 0.12).19 The development of a blue emitter with high color
purity, high efficiency, and a long lifetime has proved extremely
challenging. It is difficult to produce highly efficient blue light
Most studies of blue emitters have tested molecules with
excellent uorescence characteristics such as anthracene, pyr-
ene, and uorine as single core or side moieties.20–25 Many
studies have investigated the use of anthracene and pyrene as
the single cores of blue emitting materials since they have high
PL efficiencies. In our previous study, the blue emissions of
many anthracene derivatives with a single core moiety were
investigated.26–28 We synthesized and investigated new blue
emitting materials that have symmetric or asymmetric chemical
structures with bulky side groups, and in particular introduced
anthracene as a single core and m-terphenyl and triphe-
nylbenzene groups as side groups based on a core-side
concept.26 In addition, we investigated the electroluminescence
properties that arise when diphenylamine and triphenylamine
side groups are attached to the core, which means that there is
electron donation in the emitter that occurs from the side
groups to the core moiety.27 To determine the effects of varying
the positions of the links between the core and the side groups,
we showed that the link position could be changed into ortho,
meta and para to change emission wavelengths and strengthen
emission efficiency according to the position of a side group.29
aDepartment of Chemistry, The Catholic University of Korea, Bucheon, 420-743, South
Korea. E-mail: hahapark@catholic.ac.kr; Fax: +82 2 2164 4764; Tel: +82 2 2164 4821
bDepartment of Polymer Science and Engineering & Department of IT Convergence,
Korea National University of Transportation, Chungju, 380-702, South Korea.
E-mail: jihoonli@ut.ac.kr; Fax: +82 43 841 5420; Tel: +82 43 841 5427
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c4tc00075g
‡ Hayoon Lee and Beomjin Kim contributed equally to this work.
This journal is © The Royal Society of Chemistry 2014
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Moreover, we recently reported the syntheses of new dual
core chromophore materials containing anthracene and pyrene
that exhibit high PL efficiencies.30 There is a dihedral angle of
approximately 90ꢁ between the two chromophores in a dual core
composed of anthracene and pyrene. Compounds based on
dual cores have advantages such as the prevention of excimer
formation and improvements in the efficiency and lifetime of
devices. However, there has been a lack of research into such
dual core materials; no systematic study of the substitution of
side groups onto dual cores has previously been performed.
In this study, we introduced phenyl and naphthyl groups
onto various positions of dual cores in order to investigate the
changes in the efficiencies of the rst and the second core
moieties. The newly synthesized compounds are blue emitting
materials that have asymmetric or symmetric structures and
that exhibit high efficiencies. The underlying dual core of the
newly synthesized compounds is 1-anthracen-9-yl-pyrene (AP-
core). The asymmetric structures 1-naphthalen-1-yl-6-(10-
Scheme 1 Chemical structures of the new blue emitting materials.
phenyl-anthracen-9-yl)-pyrene (Ph-AP-Na) and 1-(10-naph- rst occur at the anthracene moiety. When the electron density
thalen-1-yl-anthracen-9-yl)-6-phenyl-pyrene (Na-AP-Ph), and the distribution of Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph and Na-AP-Na is
symmetric structures 1-phenyl-6-(10-phenyl-anthracen-9-yl)- considered, it is almost the same (Fig. S1†). It can be seen that
pyrene (Ph-AP-Ph) and 1-naphthalen-1-yl-6-(10-naphthalen-1-yl- anthracene and pyrene function as the rst and second cores
anthracen-9-yl)-pyrene (Na-AP-Na) were synthesized. The respectively in AP-core derivatives.
thermal and electro-optical properties of these materials were
This conclusion is supported by the results of the time-
characterized by using differential scanning calorimetry (DSC), dependent density functional theory (TD-DFT) calculations in
thermogravimetric analysis (TGA), as well as ultraviolet-visible Table 2. The HOMO / LUMO transition and the HOMOꢀ1 /
(UV-vis) and photoluminescence (PL) spectroscopies. Multilay- LUMO transition are respectively 71.8% and 17.1% at 390 nm,
ered EL devices were fabricated with these materials as non- which has the highest oscillator strength of the AP-core.
doped emitting layers.
Accordingly, it can be seen that intramolecular charge transfer
(ICT) arises from pyrene to anthracene and that pyrene func-
tions as the second core. In the case of Na-AP-Na, the contri-
butions of the HOMO / LUMO transition and the HOMOꢀ1
/ LUMO transition are 59.5% and 34.5% respectively at
Results and discussion
Synthesis and optical properties
Scheme 1 shows the chemical structures of the synthesized 400 nm, which has the highest oscillator strength, so the
compounds. Ph-AP-Na and Na-AP-Ph have asymmetric chemical contribution of the HOMOꢀ1 / LUMO transition is consid-
structures and Ph-AP-Ph and Na-AP-Na have some symmetry. A erably greater than that in the other compounds.
dual core mainly consisted of anthracene and pyrene groups
In the case of Na-AP-Ph, the contributions of the HOMO /
and a side group was used with phenyl and naphthyl groups. All LUMO transition and the HOMOꢀ1 / LUMO transition are
compounds were puried with reprecipitation and the column 62.5% and 23.1% respectively at 399 nm, which has the highest
chromatography method. The synthesized compounds were oscillator strength, so the contribution of pyrene to the
characterized by using nuclear magnetic resonance (NMR) HOMOꢀ1 / LUMO transition is still signicant, even though it
spectroscopy, elemental analysis, and FAB mass analysis. All the is smaller than that in Na-AP-Na. In the cases of Ph-AP-Na and
synthesis methods are shown in Scheme 2. Boronylation, Ph-AP-Ph, the contribution of the HOMO / LUMO transition is
bromination, and Suzuki aryl–aryl coupling reactions were used dominant and the contributions of the HOMOꢀ1 / LUMO
in the syntheses. The synthesis methods are described in more transition are respectively 5.5% and 6.7% at 399 nm, which has
detail in the Experimental section.
the greatest oscillator strength. Accordingly, it can be seen that
The optical properties of the synthesized compounds are the HOMOꢀ1 / LUMO transition is made from pyrene even if
summarized in Table 1. The absorption peak wavelengths of its contribution is smaller than the other two compounds.
synthesized compounds, AP-core, Ph-AP-Na, Na-AP-Ph, Ph-AP- Further, when the substituent of anthracene is changed from
Ph and Na-AP-Na in the solution and lm state appear in the phenyl to naphthyl, the pyrene transition portion of the
range of 350 to 400 nm.
HOMOꢀ1 / LUMO transition increases. Thus, anthracene and
According to the HOMO and LUMO electron density distri- pyrene function effectively as dual cores because the HOMOꢀ1
butions of the AP-core, more electrons are located in anthracene / LUMO transition occurs even though the HOMO / LUMO
than in pyrene (Fig. 1). However, the electron densities of transition is dominant in all ve compounds.
HOMOꢀ1 and LUMO+1 indicate that many electrons are
The relative PL quantum efficiencies (QEs and Ff) of the
distributed in pyrene. It means that the main electron transfer synthesized compounds in the solution state were determined
from the excited state to the ground state aer excitation can as described previously.26,31
4738 | J. Mater. Chem. C, 2014, 2, 4737–4747
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Scheme 2 Synthetic routes for the AP-core, Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na.
ꢀ
ꢁ
2
and the standard at the excitation wavelength respectively, and hA
and href are the refractive indices of the corresponding solvents
(pure solvents were assumed). The QEs of the ve compounds
were compared, as shown in Table 1. The QE of the AP-core is
0.76. Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na have QEs
between 0.85 and 0.96. Na-AP-Na has the highest value, 0.96.
The PL maximum values of the ve compounds were
compared. The PL maximum of the AP-core is 434 nm in the
PLA
UVref
PLref
hA
FFðAÞ ¼ FFðrefÞ ꢂ
ꢂ
ꢂ
(1)
UVA
href
FF(A) is the relative FF of the ve synthesized compounds in
CHCl3 solution. Here, FF(ref) ¼ 0.91 (QE in ethanol solution of
9,10-diphenylanthracene) was used. PLA and PLref are the inte-
grated emission intensities of the sample and the standard
respectively. UVA and UVref are the absorbances of the sample
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Table 1 Optical, electrical, and thermal properties of the synthesized compounds
Solutiona
Film on glass
em
ab
em
l
FWHMb
(nm)
l
max
l
FWHMb
(nm)
HO MOd
(eV)
LU MO
(eV)
Band gap
(eV)
Tg
Td
max
max
ab
Compounds
AP-core
l
max
(nm)
(nm)
434
442
444
443
443
(nm)
(nm)
453
451
453
450
450
Ffc
(ꢁC)
(ꢁC)
330, 343,
369, 389
354, 378,
399
359, 378,
399
358, 378,
399
358, 378,
399
59
55
57
56
56
337, 352,
375, 396
363, 382,
404
364, 382,
404
364, 382,
404
363, 382,
404
75
60
63
59
58
0.76
0.95
0.85
0.92
0.96
ꢀ5.75
ꢀ5.75
ꢀ5.71
ꢀ5.78
ꢀ5.78
ꢀ2.77
ꢀ2.84
ꢀ2.77
ꢀ2.82
ꢀ2.87
2.98
2.91
2.94
2.96
2.91
92
256
181
228
218
329
432
432
439
450
Ph-AP-Na
Na-AP-Ph
Ph-AP-Ph
Na-AP-Na
a
b
c
CHCl3 solution (1.00 ꢂ 10ꢀ5 M). Full width at half maximum. Relative photoluminescence efficiency in CHCl3 solution using 9,10-
d
diphenylanthracene as the reference (absolute photoluminescence efficiency, Ff ¼ 0.91 in EtOH). Ultraviolet photoelectron spectroscopy
(Riken-Keiki, AC-2).
connected to the anthracene group in the core, this connection
does not affect the conjugation length signicantly or the PL
maximum value because anthracene and pyrene, the two
chromophores in the AP-core, are orthogonally connected at an
angle of 93.2ꢁ; this orthogonal structure prevents conjugation
and any red-shi in the PL maximum value (Fig. 2).
According to the FWHM results for Ph-AP-Na, Na-AP-Ph, Ph-
AP-Ph, and Na-AP-Na, the presence of a side group results in
slight decreases by 2 to 4 nm in the solution state and large
decreases by 12 to 17 nm in the lm state compared to the
results for the AP-core. These decreases arise because packing is
prevented by the side groups. The FWHMs for the lm state are
higher than those for the solution state because the spectrum
becomes broader when the molecules pack in the lm state,
which is tighter than packing in the solution state. In the case of
the AP-core, the increase in the value of the FWHM is 16 nm,
whereas the increases for Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and
Na-AP-Na are in the range 2 to 6 nm. In other words, the FWHM
values of Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na decrease
by 10 nm or more compared with that of the AP-core. Thus, the
EL device color coordinates of the four compounds are expected
to be superior to the color coordinates of the AP-core in the blue
Fig. 1 Electron density distributions of HOMOꢀ1, HOMO, LUMO and
region because their FWHM values are less than that of the AP-
core. The UV-vis absorption and PL patterns of the ve
compounds are similar on the whole regardless of whether
phenyl or naphthyl side groups are present (Fig. 3).
LUMO+1 in the AP-core calculated with B3LYP/6-311G(d).
solution state, whereas those of the other compounds lie
between 442 and 444 nm, i.e. a 10 nm shi with respect to that
of the AP-core. This shi can be explained by the extended
conjugation lengths of the phenyl and naphthyl groups of
anthracene, which are similar to those of conventional single
core compounds based on anthracene.26 The PL maximum
values of the four synthesized compounds with side groups are
similar because there are no special dipole moieties in the side
groups. The ve compounds exhibit similar PL maximum
values in the lm state, between 450 and 453 nm. In the lm
state, the phenyl and naphthyl side groups have no clear effect
on the PL maxima. Although the pyrene group is directly
Electrochemical and thermal properties
The highest occupied molecular orbital (HOMO) levels were
determined by photoelectron spectroscopy by using an ultra-
violet light energy source. The lowest unoccupied molecular
orbital (LUMO) energy levels were obtained from the HOMO
levels and the optical band gaps (Table 1). The optical band gaps
were derived by determining the absorption edges from plots of
(hn) vs. (ahn)2, where a, h, and n are the absorbance, Planck's
constant, and the frequency of light, respectively. The HOMO
4740 | J. Mater. Chem. C, 2014, 2, 4737–4747
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Table 2 Absorption frequencies and oscillator strengths calculated with TD-B3LYP/6-311G(d) for the AP-core, Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph,
and Na-AP-Na
Compounds
AP-core
Wavelength (nm)
397
Oscillator strength
0.0327
Characteristic of transition
Contributiona (%)
HOMOꢀ1 / LUMO
HOMO / LUMO
48.3
25.1
25.6
33.4
65.7
17.1
2.5
71.8
7.0
99.1
5.5
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMOꢀ1 / LUMO+1
HOMO / LUMO
HOMO / LUMO+1
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMOꢀ1 / LUMO+1
HOMO / LUMO
395
390
0.0007
0.1262
Ph-AP-Na
Na-AP-Ph
405
399
0.0009
0.2637
2.1
90.7
93.6
5.3
398
407
0.0162
0.0414
HOMOꢀ1 / LUMO
HOMO / LUMO
HOMOꢀ1 / LUMO
HOMO / LUMO
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMO / LUMO
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMOꢀ1 / LUMO+1
HOMO / LUMO
HOMO / LUMO+1
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMO / LUMO
3.9
18.6
76.0
70.4
14.5
14.3
23.1
5.9
62.5
6.9
97.7
92.2
6.6
405
399
0.0339
0.2434
Ph-AP-Ph
Na-AP-Na
408
403
0.0031
0.0140
399
0.2863
HOMOꢀ1 / LUMO
HOMOꢀ1 / LUMO+1
HOMO / LUMO
6.7
3.7
87.4
4.1
94.8
34.5
59.5
3.5
405
400
0.0103
0.1848
HOMO / LUMO
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMO / LUMO
HOMO / LUMO+1
HOMOꢀ1 / LUMO
HOMO / LUMO
399
0.1078
64.1
32.1
a
Contribution (%) ¼ (coefficient)2 ꢂ 2 ꢂ 100.
and LUMO levels of the synthesized compounds were found
to be in the ranges ꢀ5.71 to ꢀ5.78 eV and ꢀ2.77 to ꢀ2.87 eV
respectively.
The glass transition temperatures (Tg) and the decomposi-
tion temperatures (Td) of the synthesized compounds were
determined with DSC and TGA respectively, and are summa-
rized in Table 1. The Tg of the AP-core is 92 ꢁC. The Tg values of
Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na are 256 ꢁC,
181 ꢁC, 228 ꢁC, and 218 ꢁC, respectively, approximately 100 ꢁC to
150 ꢁC higher than that of the AP-core. The Td values of the AP-
ꢁ
core, Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na are 329 C,
432 ꢁC, 432 ꢁC, 439 ꢁC, and 450 ꢁC, respectively. Note that these
high Tg and Td values indicate that the thermal properties of the
compounds containing side groups are excellent; this
improvement in thermal properties over those of the AP-core
could be due to their increased molecular weights. In general,
the thermal properties of lms used in OLEDs are strongly
Fig. 2 Molecular structure of the AP-core optimized with B3LYP/6-
311G(d).
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Fig. 3 UV-visible absorption spectra and PL spectra of the synthesized materials: (a) in CHCl3 solution (1.00 ꢂ 10ꢀ5 M) and (b) in the thin film
state.
associated with the device lifetime because Joule heating arises
during device operation.32 Therefore, devices containing these
dual core materials with side groups are expected to exhibit long
lifetimes under operation.
Fig. 4 shows surface atomic force microscopy (AFM) images
of lms of the dual core derivatives: obtained immediately aer
vacuum deposition (Fig. 4(a)) and aer storage for 1 day at
100 ꢁC under an argon atmosphere (Fig. 4(b)). Immediately aer
deposition, the root mean square (RMS) roughness values of the
lms of the AP-core, Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph and Na-AP-
Na were 0.3 nm, 0.6 nm, 0.3 nm, 0.4 nm, and 0.6 nm, respec-
tively. The AP-core lm has an RMS value of 43.2 nm aer 1 day
at 100 ꢁC under an argon atmosphere, which is 144 times higher
than that obtained immediately aer vapor deposition.
However, the four compounds with side groups do not
undergo any changes due to heat annealing; in fact, their RMS
values are improved by this process. Examination of the AFM
results shows that the dual core compounds with side groups
have excellent characteristics aer thermal annealing treat-
ment. This result can be explained in terms of the high Tg and
Td values mentioned above.
Electroluminescence and thermal properties
The synthesized compounds were used as non-doped emitting
layers (EMLs) in OLEDs with the following structures: ITO/2-
TNATA (60 nm)/NPB (15 nm)/synthesized compound (35 nm)/
Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). The OLED properties are
summarized in Fig. 5 and Table 3.
The EL maximum values of the AP-core, Ph-AP-Na, Na-AP-Ph,
Ph-AP-Ph, and Na-AP-Na devices are between 455 and 463 nm.
While the FWHM value of the EL of the AP-core is 77 nm, those
of Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na are in the
range 57 to 62 nm, which is 15 to 20 nm narrower than the value
Fig. 4 AFM images of the AP-core, Ph-AP-Na, Na-AP-Ph, Ph-AP-Ph,
and Na-AP-Na: (a) obtained immediately after evaporation and (b)
after treatment at 100 ꢁC for 1 day in an argon atmosphere.
for the AP-core. This difference is similar to the result for the PL
FWHM in the lm state and the overall EL spectra are similar
(Table 3 and Fig. 5(a)).
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molecular packing with respect to that of the AP-core due to
their side groups. Fig. 5(b) clearly shows the difference between
the luminance efficiencies of the core compound and the core-
side compounds. As shown in Fig. 5(c), the LUMO levels of Ph-
AP-Na, Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na are similar and are in
the range ꢀ2.77 to ꢀ2.87 eV. The differences between these
LUMO levels and the LUMO level of Alq3 (used as the electron
transporting layer (ETL)) are small, in the range 0.23 to 0.13 eV,
which means that the injection of electrons is facile. Therefore,
the charge carrier balance is considered to be good.
We now analyze the luminance efficiency data more closely.
Note that Ph-AP-Na and Ph-AP-Ph, in which the anthracene core
is substituted with phenyl groups, have similar efficiencies, 5.18
cd Aꢀ1 and 5.11 cd Aꢀ1. Ph-AP-Na has an efficiency slightly
greater than that of Ph-AP-Ph. In Na-AP-Ph and Na-AP-Na, the
anthracene core is substituted with naphthyl groups; the
luminance efficiencies of these compounds are 5.28 cd Aꢀ1 and
5.46 cd Aꢀ1 respectively, which are higher than those of Ph-AP-
Na and Ph-AP-Ph. The value for Na-AP-Na is the highest effi-
ciency of the synthesized compounds. Therefore, the substitu-
tion of naphthyl at the anthracene core (the rst core) improves
the efficiency more than the substitution of phenyl. Also, the
substitution of naphthyl at the second core of pyrene can
improve the luminescence efficiency compared to phenyl
substitution. The fact that Na-AP-Na has the highest luminance
efficiency of this series of compounds coincides with the rela-
tive PL efficiency data shown in Table 1.
However, the order of the compounds in terms of EL effi-
ciency does not exactly match that in terms of PL efficiency.
Several factors may account for this observation, including
charge transporting properties, HOMO and LUMO electronic
levels, and charge balance of holes and electrons in the device.
I–V and L–V curves are shown in Fig. S3;† however, these curves
were obtained from devices that were not fully optimized for
each compound. Further studies are underway to clarify this
issue.
According to the CIE data, AP-core, Ph-AP-Na, Na-AP-Ph, Ph-
AP-Ph, and Na-AP-Na have similar color coordinates. However,
the FWHM of the AP-core is 77 nm, which is larger than those of
the other compounds. This trend is the same as obtained for the
PL FWHMs in the lm state, and it indicates that packing is
Fig. 5 EL characteristics of devices using the synthetic materials as
EMLs: (a) EL spectra and CIE diagram, (b) luminance efficiency versus
current density, and (c) energy diagrams of the compounds.
The AP-core device has an efficiency of 3.34 cd Aꢀ1 but the prevented by the side groups. As a result, the color coordinates
luminance efficiencies of the devices containing the four of the AP-core are (0.170, 0.200); this y value is not satisfactory
compounds with side groups are higher, between 5.11 and 5.46 for blue color applications. In contrast, the coordinates for the
cd Aꢀ1. This increase in efficiency can be explained in terms of dual core compounds with side groups Ph-AP-Na, Na-AP-Ph, Ph-
the higher PL efficiency of the four compounds and the lower AP-Ph, and Na-AP-Na are (0.151, 0.142), (0.144, 0.137), (0.152,
energy transfer loss that arises because of the decreased 0.125), and (0.143, 0.131), respectively, which are good x and y
Table 3 ITO/2-TNATA (60 nm)/NPB (15 nm)/EML (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm)/at 20 mA cmꢀ2
Emitting
material (EML)
Operating
voltage (V)
ELmax
(nm)
FWHM
(nm)
Luminance
Power efficiency
efficiency (cd Aꢀ1
)
(lm Wꢀ1
)
CIE (x, y)
AP-core
7.77
8.39
8.86
7.56
9.27
460
461
463
455
463
77
62
60
57
62
3.34
5.18
5.28
5.11
5.46
1.46
2.15
2.11
2.35
2.05
(0.170, 0.200)
(0.151, 0.142)
(0.144, 0.137)
(0.152, 0.125)
(0.143, 0.131)
Ph-AP-Na
Na-AP-Ph
Ph-AP-Ph
Na-AP-Na
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color coordinates in the blue region. Blue emitters require a y by using a Lambda 1050 UV/Vis/NIR spectrometer (Perki-
CIE coordinate value of less than 0.16 for the large color gamut nElmer). A PerkinElmer luminescence spectrometer LS50
of mobile displays and tablet PC applications, according to the (xenon ash tube) was used to perform photoluminescence (PL)
National Television System Committee (NTSC) blue color stan- spectroscopy. The glass-transition temperatures (Tg) of the
dard (0.14, 0.08).
compounds were determined with differential scanning calo-
Further, we measured the average lifetimes of the synthe- rimetry (DSC) under a nitrogen atmosphere by using a DSC4000
sized compound devices at 1000 cd mꢀ2. The lifetime of the AP- (PerkinElmer). Samples were heated to 360 or 400 ꢁC at a rate of
core device is 91 h. In contrast, the lifetimes of the Ph-AP-Na, 10 ꢁC minꢀ1 and cooled at 10 ꢁC minꢀ1 then heated again under
Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na devices are 170 h, 305 h, the same heating conditions as used in the initial heating
215 h, and 298 h, respectively, which are approximately 1.9 to process. Degradation temperatures (Td) were determined with
3.4 times longer than that of the AP-core device. These thermogravimetric analysis (TGA) by using a TGA4000 (Perꢀk1i-
increased lifetimes are due to their high luminance efficiencies nElmer). Samples were heated to 800 ꢁC at a rate of 10 ꢁC min
.
and excellent thermal properties. A high luminance efficiency
The HOMO energy levels were determined with ultraviolet
means that the current density is smaller and that less Joule photoelectron yield spectroscopy (Riken Keiki AC-2). The LUMO
heating occurs for the same device brightness. The excellent energy levels were derived from the HOMO energy levels and the
thermal properties of these compounds mean that they are band gaps. Atomic force microscopy (AFM) was performed in
more robust than the AP-core under given heating conditions. the tapping-mode by using a Multimode IIIa (Digital Instru-
ments). The molecular structures were optimized by using time-
dependent DFT (TD-DFT) on the optimized structures. In the
Conclusions
TD-DFT calculations, the same exchange-correlation functional
Five new dual core derivatives with high PL efficiencies based on and basis sets were employed as used in the DFT calculations
anthracene and pyrene moieties, AP-core, Ph-AP-Na, Na-AP-Ph, (TD-B3LYP/6-311G(d)). All DFT and TD-DFT calculations were
Ph-AP-Ph, and Na-AP-Na, were synthesized and their electrical performed with the Gaussian09 program.33
properties were characterized. Four of the dual core compounds
In each of the EL devices, tris(N-(naphthalen-2-yl)-N-phenyl-
contain side groups with systematic variation in size and amino)triphenylamine (2-TNATA) was used for the hole injec-
substitution position. The dihedral angle between the two core tion layer (HIL), N,N0-bis(naphthalen-1-yl)-N,N0-bis(phenyl)
chromophores of the AP-core is 93.2ꢁ, which prevents the benzidine (NPB) was used for the hole transporting layer (HTL),
lengthening of the conjugation. As a result, the UV-visible one of the synthetic materials AP-core, Ph-AP-Ph, Na-AP-Na, Ph-
absorption peak and the PL emission peak are nearly identical. AP-Na, and Na-AP-Ph was used as the emitting layer (EML),
The efficiency of the AP-core can be improved by substituting 8-hydroxyquinoline aluminum (Alq3) was used for the electron
its large naphthyl component with the rst core anthracene and transporting layer (ETL), lithium uoride (LiF) was used for the
the second core pyrene. Na-AP-Na exhibits a high luminance electron injection layer (EIL), and ITO was used as the anode
efficiency, 5.46 cd Aꢀ1, in a non-doped device and good color and Al as the cathode. All organic layers were deposited under
ꢀ1
coordinates of (0.143, 0.131) that are applicable to displays 10ꢀ6 Torr, with a rate of deposition of 1 A s to create an
requiring a blue emitter. Thus an orthogonally connected dual emitting area of 4 mm2. The LiF and aluminum layers were
core can be used to produce a blue emission spectrum and continuously deposited under the same vacuum conditions.
prepare blue emitting materials. The side groups can be varied The luminance efficiency data for the fabricated EL devices were
to strengthen the EL efficiency. The FWHM values of Ph-AP-Na, obtained by using a Keithley 2400 sourcemeter. Light intensities
Na-AP-Ph, Ph-AP-Ph, and Na-AP-Na are 15 to 20 nm narrower were obtained with a Minolta CS-1000A spectroradiometer. The
than the value for the AP-core. The dual core compounds operational stabilities of the devices were measured under
with side groups have excellent characteristics such as high encapsulation in a glove box. The device lifetimes were deter-
Tg and Td values compared to the AP-core. The lifetime of the mined by using the Polaronix OLED Lifetime Test System of
Na-AP-Na device was more than three times longer than the McScience.
˚
AP-core device.
Moreover, by introducing chromophores other than anthra-
cene and pyrene, many different dual core systems can be
Synthesis
prepared. In addition to side groups composed of aromatic
Compound 1. 9-Bromoanthracence (10.0 g, 38.9 mmol) was
rings, electron-donating or electron-withdrawing groups could dissolved in anhydrous THF solution (500 mL) and stirred at
ꢁ
be substituted to improve OLED device performance.
ꢀ78 C. Then, 1.6 M n-BuLi (29.3 mL, 46.7 mmol) was added.
Triethyl borate (9.3 mL, 54.5 mmol) was added to the reaction
aer 30 min. Aer the reaction had nished, the solution was
acidied with 2 N HCl solution at room temperature and
extracted with ethyl acetate and water. The organic layer was
Experimental
General information
The 1H-NMR spectra and 13C-NMR spectra were recorded on dried over anhydrous MgSO4 and ltered. The solution was
Bruker Avance 300 and Avance 500 spectrometers. The FAB+- evaporated. The residue was re-dissolved in ethyl acetate and
mass and EI+-spectra were recorded on a JEOL, JMS-AX505WA, hexane was added into the solution. The precipitate was ltered
HP5890 series II. The optical absorption spectra were obtained and washed with hexane to obtain a beige compound (7.70 g,
4744 | J. Mater. Chem. C, 2014, 2, 4737–4747
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Journal of Materials Chemistry C
89%). 1H-NMR (300 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 8.47 (s, 1H),
8.14 (d, J ¼ 9.2 Hz, 2H), 8.04 (d, J ¼ 9.8 Hz, 2H), 7.53–7.44 (m,
4H), 5.07 ppm (s, 2H), EI+-Mass: 222.
Compound 6. 4 (1.0 g, 2.19 mmol), phenyl boronic acid (0.44
g, 3.61 mmol), Pd(OAC)2 (0.02 g, 0.09 mmol), and (cyclohexyl)3P
(0.04 g, 0.14 mmol) were added to anhydrous THF (100.0 mL)
solution. Then tetraethylammonium hydroxide (20 wt%) (10.0
mL) was addeꢁd to the reaction mixture at 50 ꢁC. The mixture was
heated to 80 C for 2 h under nitrogen. Aer the reaction had
nished, the reaction mixture was extracted with CHCl3 and
water. The organic layer was dried over anhydrous MgSO4 and
ltered. The solution was evaporated. The residue was re-dis-
solved in CHCl3 and added to ethanol. The precipitate was
ltered and washed with ethanol. The yellow powder was puried
by using column chromatography with CH2Cl2–n-hexane (1 : 7)
as the eluent to afford a white solid (0.70 g, 70%). 1H-NMR (300
MHz, CDCl3, 25 ꢁC, TMS): d ¼ 8.65 (s, 1H), 8.37 (d, J ¼ 7.8 Hz, 1H),
8.30 (d, J ¼ 9.3 Hz, 1H), 8.19–8.13 (m, 4H), 8.05 (d, J ¼ 7.8 Hz, 1H),
8.01 (d, J ¼ 7.8 Hz, 1H), 7.83 (d, J ¼ 9.2 Hz, 1H), 7.69 (d, J ¼ 8.3 Hz,
2H), 7.62 (t, J ¼ 7.05 Hz, 2H), 7.53–7.44 (m, 3H), 7.38 (t, J ¼ 8.9 Hz,
3H), 7.23 ppm (d, J ¼ 9.1 Hz, 2H), EI+-Mass: 454.
Compound 2. Bromine (10.0 mL, 194.7 mmol) in CHCl3
(500 mL) was dropped into a solution of pyrene (20.0 g, 98.9
mmol) in CHCl3 (500 mL) over 5 h while stirring. The precipitate
was collected aer 12 h and resolved by fractional crystallization
from xylene (11.8 g, 33%). 1H-NMR (300 MHz, CDCl3, 25 ꢁC,
TMS): d ¼ 8.50 (d, J ¼ 9.2 Hz, 2H), 8.29 (d, J ¼ 8.2 Hz, 2H), 8.16
(d, J ¼ 9.3 Hz, 2H), 8.09 ppm (d, J ¼ 8.2 Hz, 2H), EI+-Mass: 360.
Compound 3 (AP-core). 1 (0.47 g, 2.12 mmol), 1-bromopyr-
ene (0.50 g, 1.78 mmol), and Pd(PPh3)4 (0.103 g, 0.089 mmol)
were added to anhydrous toluene solution (50.0 mL). Then, 2 M
K2CO3 solution (7.0 mL) dissolved in H2O was added to the
reaction mixture at 50 ꢁC aer pouring anhydrous ethꢁanol (20.0
mL) into the mixture. The mixture was heated to 65 C for 4 h
under nitrogen. Aer the reaction had nished, the reaction
mixture was extracted with toluene and water. The organic layer
was dried over anhydrous MgSO4 and ltered. The solution was
evaporated. The product was isolated with silica gel column
chromatography by using CH2Cl2–n-hexane (1 : 7) as the eluent
Compound 7. This compound was synthesized with the
same method as for compound 8 by using 5 (0.7 g, 1.38 mmol).
Accordingly, a yellow solid (0.28 g, 34%) was obtained. 1H-NMR
(300 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 8.73 (dd, J ¼ 8.9 Hz, 2H), 8.34
(d, J ¼ 7.8 Hz, 1H), 8.24 (d, J ¼ 7.9 Hz, 1H), 8.05 (t, J ¼ 7.8 Hz,
5H), 7.90 (d, J ¼ 9.2 Hz, 1H), 7.80 (d, J ¼ 9.1 Hz, 1H), 7.72–7.50
(m, 6H), 7.45–7.23 ppm (m, 6H). EI+-Mass: 582.
1
to afford a beige solid (0.50 g, 74%). H-NMR (300 MHz, [D8]
THF): d ¼ 8.70 (s, 1H), 8.44 (d, J ¼ 7.8 Hz, 1H), 8.29 (d, J ¼ 8.7 Hz,
2H), 8.23 (d, J ¼ 9.0 Hz, 1H), 8.17 (d, J ¼ 9.6 Hz, 3H), 8.04–7.99
(m, 2H), 7.80 (d, J ¼ 9.0 Hz, 1H), 7.47 (t, J ¼ 6.6 Hz, 2H), 7.32 (d,
J ¼ 7.8 Hz, 2H), 7.26 (d, J ¼ 9.0 Hz, 1H), 7.22 ppm (t, J ¼ 6.3 Hz,
2H); 13C-NMR (300 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 135.53, 134.12,
131.66, 131.49, 131.28, 130.99, 129.58, 128.68, 127.94, 127.88,
127.71, 127.27, 127.23, 126.33, 125.91, 125.83, 125.47, 125.44,
125.38, 125.12, 125.03, 124.91 ppm; HRMS (EI, m/z): [M+] calcd
for C30H18, 378.1409; found, 378.1414. Anal. calcd for C30H18: C
95.21, H 4.79; found: C 95.21, H 4.73%.
Compound 8. 6 (0.70 g, 1.53 mmol) and N-bromosuccinimide
(NBS) (0.30 g, 1.68 mmol) were added to CHCl3 (50.0 mL), and
acetic acid (1.0 mL) was added to the reaction mixture. The
mixture was reuxed for 3 h. Aer the reaction had nished,
the reaction mixture was extracted with CHCl3 and water. The
organic layer was dried over anhydrous MgSO4 and ltered. The
solution was evaporated. The residue was re-dissolved in acetone
and added to CHCl3. The precipitate was ltered and washed
with acetone to obtain a yellow compound (0.23 g, 28%). 1H-NMR
(300 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 8.72 (d, J ¼ 8.9 Hz, 2H), 8.38
(d, J ¼ 8.34 Hz, 1H), 8.32 (d, J ¼ 8.8 Hz, 1H), 8.19 (d, J ¼ 10.7 Hz,
2H), 8.02 (dd, J ¼ 7.7 Hz, 2H), 7.84 (d, J ¼ 9.1 Hz, 1H), 7.69 (d, J ¼
6.0 Hz, 2H), 7.63 (t, J ¼ 7.7 Hz, 4H), 7.54 (t, J ¼ 7.2 Hz, 1H), 7.38
(d, J ¼ 8.7 Hz, 2H), 7.31–7.22 ppm (m, 3H). EI+-Mass: 532 [M+].
Compound 9. 4 (1.0 g, 2.19 mmol) and N-bromosuccinimide
(NBS) (0.43 g, 2.41 mmol) were added to CHCl3 (30.0 mL) and
acetic acid (5.0 mL) was added to the reaction mixture. The
mixture was reuxed for 2 h. Aer the reaction had nished,
the reaction mixture was extracted with CHCl3 and water. The
organic layer was dried over anhydrous MgSO4 and ltered. The
solution was evaporated. The residue was re-dissolved in
ethanol and added to CHCl3. The precipitate was ltered and
washed with ethanol to obtain a yellow compound (1.1 g, 96%).
1H-NMR (300 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 8.71 (d, J ¼ 8.1 Hz,
2H), 8.60 (d, J ¼ 9.2 Hz, 1H), 8.44 (d, J ¼ 7.8 Hz, 1H), 8.35 (d, J ¼
9.3 Hz, 1H), 8.28 (d, J ¼ 8.2 Hz, 1H), 8.06 (d, J ¼ 7.8 Hz, 1H), 7.97
(d, J ¼ 8.3 Hz, 1H), 7.77 (d, J ¼ 9.2 Hz, 1H), 7.62 (t, J ¼ 6.3 Hz,
2H), 7.33 (d, J ¼ 3.6 Hz, 2H), 7.30 (d, J ¼ 5.3 Hz, 1H), 7.26–7.24
ppm (m, 2H), EI+-Mass: 536.
Compound 4. 1 (4.0 g, 18.0 mmol), 2 (9.7 g, 27.0 mmol), and
Pd(PPh3)4 (0.62 g, 0.54 mmol) were added to anhydrous toluene
solution (150.0 mL) and anhydrous ethanol (8.0 mL). Then, 2 M
K2CO3 solution (15.0 mL) dissolved in H2O was added to the
reaction mixture at 50 ꢁC aer pouring anhydrous ethanol
ꢁ
(8.0 mL) into the mixture. The mixture was heated to 65 C for
5 h under nitrogen. Aer the reaction had nished, the reaction
mixture was extracted with toluene and water. The organic layer
was dried over anhydrous MgSO4 and ltered. The solution was
evaporated. The product was isolated with silica gel column
chromatography by using CH2Cl2–n-hexane (1 : 7) as the eluent
1
to afford a beige solid (3.9 g, 32%). H-NMR (300 MHz, CDCl3,
25 ꢁC, TMS): d ¼ 8.65 (s, 1H), 8.58 (d, J ¼ 9.3 Hz, 1H), 8.43 (d, J ¼
7.8 Hz, 1H), 8.34 (d, J ¼ 9.3 Hz, 1H), 8.26 (d, J ¼ 8.4 Hz, 1H), 8.15
(d, J ¼ 8.4 Hz, 2H), 8.08 (d, J ¼ 7.8 Hz, 1H), 7.95 (d, J ¼ 8.1 Hz,
1H), 7.75 (d, J ¼ 9.0 Hz, 1H), 7.49 (t, J ¼ 6.3 Hz, 2H), 7.35 (t, J ¼
9.0 Hz, 3H), 7.24 ppm (t, J ¼ 6.3 Hz, 2H), EI+-Mass: 457.
Compound 5. This compound was synthesized with the
same method as for compound 6 by using 1-naphthalene
boronic acid (0.57 g, 3.31 mmol). A beige solid (0.70 g, 63%) was
obtained. 1H-NMR (300 MHz, [D8]THF): d ¼ 8.72 (s, 1H), 8.41 (d,
J ¼ 7.8 Hz, 1H), 8.29 (d, J ¼ 7.8 Hz, 1H), 8.19 (d, J ¼ 8.5 Hz, 2H),
8.09–8.01 (m, 5H), 7.92 (d, J ¼ 9.0 Hz, 1H), 7.73–7.62 (m, 3H),
7.50–7.43 (m, 3H), 7.39–7.29 (m, 5H), 7.25–7.20 ppm (m, 2H).
EI+-Mass: 504.
Compound 10 (Ph-AP-Na). 7 (1.0 g, 1.70 mmol), phenyl
boronic acid (0.32 g, 2.62 mmol), Pd(OAC)2 (0.02 g, 0.09 mmol),
This journal is © The Royal Society of Chemistry 2014
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and (cyclohexyl)3P (0.05 g, 0.18 mmol) were added to anhydrous CHCl3 and water. The organic layer was dried over anhydrous
THF (100.0 mL) solution. Then tetraethylammonium hydroxide MgSO4 and ltered. The solution was evaporated. The residue
(20 wt%) (10.0 mL) was added to the reaction mixture at 50 ꢁC. was re-dissolved in CHCl3 and added to ethanol. The precipitate
ꢁ
The mixture was heated to 80 C for 2 h under nitrogen. Aer was ltered and washed with ethanol. The yellowish powder was
the reaction had nished, the reaction mixture was extracted puried by using column chromatography with CH2Cl2–n-
with CHCl3 and water. The organic layer was dried over anhy- hexane (1 : 7) as the eluent to afford a beige solid (Ph-AP-Ph) (0.6
drous MgSO4 and ltered. The solution was evaporated. The g, 59%). 1H-NMR (500 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 8.39 (d, J ¼
residue was re-dissolved in CHCl3 and added to ethanol. The 7.5 Hz, 1H), 8.30 (d, J ¼ 9.5 Hz, 1H), 8.19 (d, J ¼ 7.0 Hz, 1H), 8.17
precipitate was ltered and washed with ethanol. The yellow (d, J ¼ 5.5 Hz, 1H), 8.10 (d, J ¼ 7.5 Hz, 1H), 8.01 (d, J ¼ 8.0 Hz,
powder was puried by using column chromatography with 1H), 7.86 (d, J ¼ 9.5 Hz, 1H), 7.80 (d, J ¼ 9.0 Hz, 2H), 7.69–7.56
CH2Cl2–n-hexane (1 : 7) as the eluent to afford a beige solid (m, 9H), 7.53 (t, J ¼ 7.5 Hz, 1H), 7.45 (d, J ¼ 9.5 Hz, 1H), 7.41 (d,
(0.55 g, 55%). 1H-NMR (300 MHz, [D8]THF): d ¼ 8.44 (d, J ¼ 7.8 J ¼ 8.5 Hz, 2H), 7.35 (t, J ¼ 6.5 Hz, 2H), 7.21 ppm (t, J ¼ 7.5 Hz,
Hz, 1H), 8.31 (d, J ¼ 7.8 Hz, 1H), 8.11–8.02 (m, 5H), 7.96 (d, J ¼ 2H); 13C-NMR (500 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 141.30, 139.11,
9.3 Hz, 1H), 7.79 (d, J ¼ 8.7 Hz, 2H), 7.74–7.50 (m, 9H), 7.42–7.29 138.14, 137.68, 135.47, 134.33, 131.43, 131.26, 130.96, 130.64,
(m, 7H), 7.23 ppm (t, J ¼ 7.2 Hz, 2H); 13C-NMR (300 MHz, CDCl3, 130.54, 130.02, 129.65, 128.86, 128.46, 128.42, 127.88, 127.81,
25 ꢁC, TMS): d ¼ 139.30, 139.11, 137.92, 136.46, 135.64, 134.65, 127.56, 127.32, 127.16, 125.84, 125.61, 125.28, 125.18, 125.11,
133.87, 133.30, 131.64, 131.41, 131.18, 131.02, 130.44, 130.23, 124.86, 124.62 ppm; HRMS (EI, m/z): [M+] calcd for C42H26,
129.90, 128.89, 128.70, 128.64, 128.49, 128.29, 128.06, 127.79, 530.2035; found, 530.2039. Anal. calcd for C42H26: C 95.06, H
127.76, 127.39, 126.93, 126.39, 126.27, 126.15, 125.67, 125.53, 4.94; found: C 95.03, H 4.98%.
125.36, 125.26, 125.12, 125.07, 124.95 ppm; HRMS (EI, m/z):
[M+] calcd for C46H28, 580.2191; found, 580.2188. Anal. calcd for lene boronic acid (0.80 g, 4.65 mmol), Pd(OAc)2 (0.04 g, 0.19
46H28: C 95.14, H 4.86; found: C 95.15, H 4.90%. mmol), and (cyclohexyl)3P (0.13 g, 0.46 mmol) were added to
Compound 11 (Na-AP-Ph). 8 (0.8 g, 1.50 mmol), 1-naphtha- anhydrous THF (100.0 mL) solution. Then, tetraethylammo-
Compound 13 (Na-AP-Na). 9 (1.0 g, 1.9 mmol), 1-naphtha-
C
lene boronic acid (0.39 g, 2.26 mmol), Pd(OAC)2 (0.02 g, 0.09 nium hydroxide (20 wt%) (10.0 mL) was added to the reaction
mmol), and (cyclohexyl)3P (0.04 g, 0.14 mmol) were added to mixture. The mixture was heated to 85 ꢁC for 2 h under
anhydrous THF (50.0 mL) solution. Then tetraethylammonium nitrogen. Aer the reaction had nished, the reaction mixture
hydroxide (20 wt%) (5.0 mL) was added to the reaction mixture was extracted with CHCl3 and water. The organic layer was dried
at 50 ꢁC. The mixture was heated to 80 ꢁC for 2 h under nitrogen. over anhydrous MgSO4 and ltered. The solution was evapo-
Aer the reaction had nished, the reaction mixture was rated. The residue was re-dissolved in CHCl3 and added to
extracted with CHCl3 and water. The organic layer was dried ethanol. The precipitate was ltered and washed with ethanol.
over anhydrous MgSO4 and ltered. The solution was evapo- The yellowish powder was puried by using column chroma-
rated. The residue was re-dissolved in CHCl3 and added to tography with CH2Cl2–n-hexane (1 : 7) as the eluent to afford a
ethanol. The precipitate was ltered and washed with ethanol. beige solid (0.60 g, 51%). 1H-NMR (300 MHz, [D8]THF): d ¼ 8.48
The yellow powder was puried by using column chromatog- (q, J ¼ 6.0 Hz, 2H), 8.34 (q, J ¼ 6.0 Hz, 2H), 8.20 (d, J ¼ 7.8 Hz,
raphy with CH2Cl2–n-hexane (1 : 7) as the eluent to afford an 2H), 8.15–8.12 (m, 3H), 8.10–7.96 (m, 11H), 7.83 (d, J ¼ 9.0 Hz,
ivory solid (0.48 g, 55%).1H-NMR (300 MHz, [D8]THF): d ¼ 8.50 1H), 7.78 (t, J ¼ 4.5 Hz, 4H), 7.73 (d, J ¼ 5.7 Hz, 2H), 7.66 (d, J ¼
(q, J ¼ 6.3 Hz, 2H), 8.32 (d, J ¼ 7.5 Hz, 2H), 8.27–8.23 (m, 4H), 6.9 Hz, 3H), 7.56–7.39 (m, 16H), 7.33–7.17 ppm (m, 14H); 13C-
8.19 (d, J ¼ 7.5 Hz, 2H), 8.14 (t, J ¼ 1.5 Hz, 2H), 8.09 (dd, J ¼ 9.0 NMR (300 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 139.11, 137.00, 136.52,
Hz, 2H), 8.04 (dd, J ¼ 7.8 Hz, 2H), 7.96 (dd, J ¼ 9.2 Hz, 2H), 7.96 135.99, 135.80, 134.62, 134.00, 133.88, 133.30, 131.42, 131.23,
(d, J ¼ 9.6 Hz, 1H), 7.77 (d, J ¼ 6.0 Hz, 1H), 7.72–7.62 (m, 7H), 131.03, 130.98, 130.46, 129.97, 129.90, 129.50, 128.91, 128.65,
7.60 (d, J ¼ 7.8 Hz, 3H), 7.52–7.41 (m, 14H), 7.32–7.16 ppm (m, 128.50, 128.44, 128.30, 128.17, 128.09, 127.78, 127.46, 126.94,
12H); 13C-NMR (300 MHz, CDCl3, 25 ꢁC, TMS): d ¼ 141.49, 126.64, 126.57, 126.40, 126.30, 126.16, 125.88, 125.67, 125.63,
138.39, 138.36, 136.99, 136.05, 135.79, 134.49, 133.98, 133.89, 125.55, 125.30, 125.09, 125.01 ppm; HRMS (EI, m/z): [M+] calcd
131.49, 131.19, 130.96, 130.86, 130.75, 129.92, 129.85, 129.54, for C50H30, 630.2347; found, 630.2345. Anal. calcd for C50H30: C
129.49, 129.06, 128.65, 128.53, 128.49, 128.41, 128.13, 128.06, 95.21, H 4.79; found: C 95.23, H 4.72%.
127.79, 127.54, 127.44, 126.93, 126.62, 126.55, 126.30, 126.27,
126.06, 125.85, 125.58, 125.52, 125.41, 125.35, 125.14, 125.11,
124.85 ppm; HRMS (EI, m/z): [M+] calcd for C46H28, 580.2191;
found, 580.2195. Anal. calcd for C46H28: C 95.14, H 4.86; found:
Acknowledgements
C 95.02, H 4.97%.
This work was supported by the National Research Foundation
Compound 12 (Ph-AP-Ph). 9 (1.0 g, 1.9 mmol), phenyl of Korea (NRF) grant funded by the Korea government (MEST)
boronic acid (0.7 g, 5.6 mmol), Pd(OAc)2 (0.04 g, 0.19 mmol), (no. 2012001846).
and (cyclohexyl)3P (0.13 g, 0.46 mmol) were added to anhydrous
THF (100.0 mL) solution. Then, tetraethylammonium hydroxide
(20 wt%) (10.0 mL) was added to the reaction mixture. The
mixture was heated to 85 C for 2 h under nitrogen. Aer the
Notes and references
ꢁ
reaction had nished, the reaction mixture was extracted with
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