Efficient blue fluorescent organic light-emitting diodes based on novel 9,10-diphenyl-anthracene derivatives

Article abstract of DOI:10.1039/c5ra11715a

A series of novel 9,10-di(naphthalen-2-yl)anthracene (ADN) derivatives were designed and synthesized as blue fluorescent emissive materials by inducing diverse aromatic groups to the C-2 position of ADN. UV-Vis absorption, fluorescence emission spectroscopy and cyclic voltammetry (CV) were carried out to generally investigate the relationships between the physical properties and molecular structures. Moreover, four non-doped OLED devices adopting OCADN, FA3PADN, FA4PADN and OC4PADN as emitting materials were fabricated to study their electroluminescence (EL) performances. Among them, a device based on OCADN exhibited highly efficient sky-blue emission with a current efficiency of 2.25 cd A^-1, power efficiency of 1.13 lm W^-1 and CIE(x, y) coordinate of (0.16, 0.30) at 8 V. In addition, the device of OC4PADN showed efficient blue emission with a CIE(x, y) coordinate of (0.16, 0.14) at 8 V.

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Efficient blue fluorescent organic light-emittingdiodes
based on novel 9,10-diphenyl-anthracene derivatives
Five 9,10-di(naphthalen-2-yl)anthracene
(ADN) derivatives with fluorenamine or
indenocarbazole moiety have been successfully developed for blue emitters of OLEDs. All
materials showed good chemical and thermal stability, moreover the OCADN based
device exhibited highly efficient sky-blue emission with current efficiency of 2.25 cd/A,
power efficiency of 1.13 lm/W and CIE(x,y) coordinate of (0.16, 0.30) at 8 V.

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PAPER
Efficient blue fluorescent organic light-emitting
diodes based on novel 9,10-diphenyl-anthracene
derivatives
Cite this: DOI: 10.1039/x0xx00000x
Hongwei Chen, +a Wenqing Liang, +b Yi Chen, a Guojian Tian, a Qingchen Dong,
*b Jinhai Huang, * a and Jianhua Su a
Received 00th January 2012,
Accepted 00th January 2012
DOI: 10.1039/x0xx00000x
A series of novel 9,10ꢀdi(naphthalenꢀ2ꢀyl) anthracene (ADN) derivatives were designed and synthesized
as blue fluorescent emissive materials by inducing diverse aromatic groups to Cꢀ2 position of ADN. UVꢀ
Vis absorption, fluorescence emission spectroscopy and cyclic voltammetry (CV) were carried out to
generally investigate the relationships between the physical properties and molecular structures. Moreover,
www.rsc.org/
four nonꢀdoped OLED devices adopting OCADN, FA3PADN, FA4PADN and OC4PADN as emitting
materials were fabricated to study their electroluminescence (EL) performances. Among them, device
based on OCADN exhibited highly efficient skyꢀblue emission with current efficiency of 2.25 cd/A,
power efficiency of 1.13 lm/W and CIE(x,y) coordinate of (0.16, 0.30) at 8 V. In addition, the device of
OC4PADN showed efficient blue emission with CIE(x,y) coordinate of (0.16, 0.14) at 8 V.
emitters have been developed to satisfy the requirements of
OLEDs in the practical usage, efficient and stable organic blue
Introduction
emitting materials are still rare.10ꢀ14 Thus, the development of
blueꢀemitting materials with high performance still remains to
be challenge.
Organic lightꢀemitting diodes (OLEDs) have attracted
enormous attentions owing to their excellent performances such
as rapid response, high brightness, flexibility, low driving
voltage and fullꢀcolor emission, etc.1ꢀ5 Because of its high
technological potential for highꢀquality flatꢀpanel displays and
solid state lighting, OLEDs have made great process and
successfully applied in mobile phones and digital cameras since
Tang and his coꢀworkers firstly introduced an efficient
OLEDs.6ꢀ9 To achieve fullꢀcolor displays, the red, green and
blue emission of relatively equal stability, efficiency and color
purity were required. Although a great number of red and green
To date, many smallꢀmolecule emitters, including
anthracene10ꢀ18, carbazole19ꢀ22, fluorine23ꢀ25, triarylamine26ꢀ28
,
and pyrene29ꢀ31 derivatives, have been reported for application
in blue OLEDs. As known to all, anthracene was widely used
as an attractive building block and starting material for
fluorescent blue emitting in OLEDs, due to its high
fluorescence quantum yield, wide energy bandꢀgap and easy
modification.1,10ꢀ18 However, the anthracene with large πꢀ
conjugation is easy to aggregate in condensed phase, leading to
fluorescence quenching and emission wavelength redꢀshift.
Thus, many endeavours have been made to avoid the planar
configuration by introducing different functionalized blocks to
the 9,10ꢀpositions of anthracene.1,32ꢀ38 For example, Shi and
Tang firstly reported a 9,10ꢀsubstitued ahthracene derivatives,
the di(2ꢀnaphthyl) anthracene (ADN), as blue emitter host in
a
Key Laboratory for Advanced Materials and Institute of Fine
Chemicals, East China University of Science & Technology,
Shanghai 200237, P. R. China. Fax:
（86）21ꢀ64252288；Eꢀmail: huangjh@eucst.edu.cn
（86）21ꢀ64252288；Tel:
b
MOE Key Laboratory for Interface Science and Engineering
in Advanced Materials and Research Center of Advanced
Materials Science and Technology, Taiyuan University of
Technology, 79 Yingze West Street, Taiyuan 030024, P.R.
China. Eꢀmail: dongqingchen@tyut.edu.cn
39
2002. But the incorporation of two perpendicular naphthyl
can not completely overcome the redꢀshifting and fluorescence
quenching problems. Therefore, some further work has been
processed about introducing different bulky groups at 2,3,6,7ꢀ
positions of ADN, and their devices showed good morphologic
stability and performance, indicating that the molecule
+ These two authors contribute equally to this work
† Electronic Supplementary Information (ESI) available: See
DOI: 10.1039/b000000x/
This journal is © The Royal Society of Chemistry 2013
J. Name., 2013, 00, 1-3 | 1

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Br
O
O
O
O
I
aggression can be remarkably suppressed by disrupting the
symmetry of ADN.40ꢀ43
Br
B
B
B
H
N
O
O
N
N
AcOK, Pd(dppf)Cl2
KOH,CuI, Orthophenanthrolene
Fluorene derivatives were also widely used in OLEDs as
blue emitter due to several advantages including their capability
of emitting in the blue region spectrum, chemical and
morphologic stability, and thermal durability under operation.23ꢀ
4
3
1
Br
O
B
O
O
O
O
O
B
B
H
N
Br
I
N
N
25
Arylamine group is wellꢀknown for its ability to transport
AcOK, Pd(dppf)Cl2
KOH,CuI, Orthophenanthrolene
charge carriers, and incorporated it into other molecules can
improve hole injection and carrier transport properties and
increase bulky volumes and thermal stability, as well as
improve device stability due to the amorphous structure, charge
balance and reduce energy consumption.26ꢀ28 And the materials
with fluorenamine or indenocarbazole group have shown
excellent holeꢀinjection and transporting capability.28,43ꢀ45
With respect to all mentioned above, in this work, five
asymmetric blue light emitting materials of the ADN
derivatives, Nꢀ(9,9ꢀdimethylꢀ9Hꢀfluorenꢀ2ꢀyl)ꢀ9,10ꢀdi(naphthaꢀ
6
5
1
Br
O
O
O
H
B
B
B
N
Br
I
O
O
O
N
7
N
KOH,CuI, Orthophenanthrolene
AcOK, Pd(dppf)Cl2
8
2
Scheme. 1 Synthetic routes of intermediates 3ꢀ8.
lenꢀ2ꢀyl)ꢀNꢀphenylꢀanthracenꢀ2ꢀamine
(naphthalenꢀ2ꢀyl)anthracenꢀ2ꢀyl)ꢀ7,7ꢀdimethylꢀ5,7ꢀdihydroꢀ
indenocarbazole OCADN), Nꢀ(3ꢀ(9,10ꢀdi(naphthalenꢀ2ꢀyl)
anthracenꢀ2ꢀyl)phenyl)ꢀ9,9ꢀdimethylꢀNꢀphenylꢀ9Hꢀfluorenꢀ2ꢀ
amine FA3PADN), 9,9ꢀdimethylꢀNꢀphenylꢀNꢀ(4ꢀ(4,4,5,5ꢀ
tetramethylꢀ1,3,2ꢀdioxaborolanꢀ2ꢀyl)phenyl)ꢀ9Hꢀfluorenꢀ2ꢀ
amine FA4PADN and 7,7ꢀdimethylꢀ5ꢀ(4ꢀ(4,4,5,5ꢀtetraꢀ
(FAADN), 5ꢀ(9,10ꢀdi
(
(
(
)
methylꢀ1,3,2ꢀdioxaborolanꢀ2ꢀyl)phenyl)ꢀ5,7ꢀdihydroindeno
carbazole (OC4PADN) were designed and synthesized. The
fluorenamine and indenocarbazole moiety which were
introduced to the 2ꢀposition of di(2ꢀnaphthyl) anthracene were
to prevent the emission redꢀshifting and fluorescence quenching
in solid, as well as to increase the hole transporting capability,
thermal stability and morphologic stability. The incorporation
of a phenyl bridge between ADN core and modified moiety is
aimed to increase the molecule twisty degree of the molecule
and reduce the πꢀelectron conjugation between the two
moieties. In order to explore the influence of these substituents
of ADN, we fully investigated the thermal and photophysical
properties and measured the HOMO and LUMO values.
Moreover, to estimate the practical utilities of these ADN
derivatives, four nonꢀdoped devices with a multilayer structure
of ITO/ PEDOT: PSS (50 nm)/ NPB (60 nm)/ ADNs (40 nm)/
TPBI (20 nm)/ LiF/ Al were fabricated. The OCADN based
device showed a reasonable good performance among these
four studied blue devices, with maximum brightness of 5839
cd/m2, current efficiency of 2.25 cd/A, power efficiency of 1.13
lm/W and a skyꢀblue color purity of CIE (0.16, 0.30).
Results and discussion
Synthesis and characterization
The synthetic routes of the intermediates and target compounds
were shown in Scheme. 1 and 2. The starting materials 1ꢀ2 and
2ꢀbromoꢀ9,10ꢀdi(naphthalenꢀ2ꢀyl)anthracene were obtained
from Shanghai Taoe chemical technology Co., Ltd. Other
intermediates 3ꢀ6 were synthesized according to literature with
Fig. 1 (a) UVꢀVis absorption spectra of all ADN derivatives in
toluene. (b) PL spectra of all ADN derivatives in toluene and
(c) PL spectra of these compounds in thin film.
2 | J. Name., 2012, 00, 1-3
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Scheme. 2 Synthetic routes of ADN derivatives.
high yields.46ꢀ48 The target products were prepared by
BuchwaldꢀHartwig and Suzuki coupling reaction between the
the range from 350 to 460 nm, which is attributed to the πꢀπ*
transition of the characteristic vibrational structures of
anthracene groups. FA4PADN and FAADN showed
broadening and redꢀshifting of the absorption spectra compared
with other three compounds due to the stronger
electron donating ability of fluorenamine moiety and their
larger πꢀelectron conjugation of molecule.
As shown in Fig. 1, all the compounds exhibited the
maximum emission wavelength at around 438ꢀ497 nm in
toluene and 453ꢀ505 nm in the solid thin film. The slight red
shifted in the emission spectrum of the thin film from the
solution could be attributed to the intermolecular πꢀπ stacking
of these ADN derivatives. All of these derivatives exhibited
blue fluorescent color both in toluene and in solid state. It
indicated that the coꢀplanarity and π conjugation of molecule
have been disrupted to some extent by the twist between
functionalized moieties and anthracene core. OCADN and
OC4PADN, which modified by indenocarbazole, showed blueꢀ
2ꢀbromoꢀ9,10ꢀdi(naphthalenꢀ2ꢀyl)anthracene
and
the
corresponding aryl amine or aryl boronic acid, then purified by
flash column chromatograph and recrystallization with yields of
32ꢀ62.5%. Repeated temperatureꢀgradient vacuum sublimation
was required for further purification of these ADN derivatives
when used in OLEDs. The molecule structures of these
compounds were characterized by 1H NMR, 13C NMR
spectroscopy, and highꢀresolution mass spectrometry (HRMS).
Photophysical properties
The absorption and emission spectra of ADN derivatives were
studied in toluene and solid thin films, which were dissolved in
dichloromethane solution with PMMA and spinꢀcoating on
quartz plates. As shown from spectra, the UVꢀVis absorption
spectrum of ADN derivatives exhibits characteristic peaks in
Table. 1 Optical and thermal properties of ADN derivatives
a
a
a
b
e
ADN
λab
λset on
λfl
Φfa (%)
λfl (nm)
HOMOc (eV)
LUMOc (eV)
Egd (eV)
Td (°C)
derivatives
(nm)
410
426
423
458
412
(nm)
431
453
445
489
431
(nm)
459
468
454
497
438
FA3PADN
FA4PADN
OCADN
38
62
46
64
46
460
483
458
505
ꢀ5.17
ꢀ5.10
ꢀ5.34
ꢀ5.02
ꢀ5.35
ꢀ2.29
ꢀ2.36
ꢀ2.55
ꢀ2.48
ꢀ2.47
2.88
2.73
2.79
2.53
2.88
423
495
408
407
492
FAADN
OC4PADN
453
b
c
aMeasured in toluene. Measured in thin film on quartz substrate. Measured versus ferrocene, The HOMO and LUMO energy
d
levels were determined using the following equations: EHOMO = [Eox − E1/2 (ferrocene)+ 4.8], ELUMO = EHOMO− Eg. Obtained
from onset of the absorption spectra by extrapolation (Eg = 1240/λset on). eMeasured by TGA at a heating rate of 10 °C minꢀ1.
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substituents at the Cꢀ2 position of ADN, all these five
compounds revealed high thermal stability and were capable of
enduring the vacuum thermal deposition process in OLED
fabrication, which suggested that the emitting layer composed
with these ADN derivates has stable morphological properties
and was desirable for OLEDs with high stability and
efficiency.40,49
shifting of the emission peaks compared to other three
compounds. It implied that the more rigid and planar
conformation of indenocarbazole effectively increased the
steric hindrance and interrupted the π conjugation between the
substituted unit and ADN core. However, the compounds with
the same substituted group (FAADN and FA4PADN or
OCADN and OC4PADN) exhibited totally different maximum
emission peak in the similar order (FA4PADN
<FAADN or
Electrochemical properties
OC4PADN OCADN). It showed that the incorporation of
<
phenyl ring significantly increased the molecule twist and
reduced the π conjugation. In addition, the maximum emission
of the paraꢀdisposition linkage compound (FA4PADN) was
observed at long wavelength with respect to that of the metaꢀ
disposition isomer (FA3PADN), it would be attributed to the
The electrochemical behavior of ADN derivatives was
investigated by cyclic voltammetry using a standard threeꢀ
electrode electrochemical cell in an electrolyte solution (0.1 M
TBAPF6/DCM), and ferrocene as external reference. The
highest occupied molecular orbital (HOMO) estimated from the
onset potentials of oxidation peak, were calculate to be ꢀ5.02 to
ꢀ5.35 eV, while the lowest unoccupied molecular orbital
(LUMO) of these derivatives measured by HOMO and band
gap energy (Eg), were calculated to be ꢀ2.29 to ꢀ2.55 eV. The
data of HOMO, LUMO energy levels and Eg was summarized
in Table 1. The HOMO levels of OCADN and OC4PADN
were lower than that of the other three compounds, which
indicated that their greater steric hindrance between the ADN
core and indenocarbazole moiety would dilute the electron
density. In addition, the HOMO energy of these ADN
derivatives were higher than those of ADN (ꢀ5.8 eV), due to the
electronꢀdonating functionalized moieties on Cꢀ2 position of
ADN. It would certainly decrease the energy barrier between
holeꢀtransporting layer and lightꢀemitting layer, and then
further improve device performance.
paraꢀdisposition linkage could partially enlarge the
conjugation between ADN core and fluorenamine group.
π
As shown in Table. 1, the fluorescence quantum yields of
OCADN OC4PADN FAADN FA3PADN and FA4PADN
,
,
,
were measured from 33% to 64% in solution. The φf data were
consistent with the PL emission, the φf of FAADN and
FA4PADN were higher than OCADN and OC4PADN in
toluene, which indicated that the fluorenamine unit enhanced
the electron donating ability of the molecule.
Thermal property
The device lifetime of OLEDs is directly related to the thermal
stability of the lightꢀemitting layer. Thus, high thermal
decomposition temperature (Td) is desirable for a lightꢀemitting
material to be utilized in OLEDs. The thermal properties of
ADN derivatives were investigated by thermogravimetry
(TGA) measurement, the relative data are listed in Table. 1 and
Electroluminescence
are shown in Fig. 2. OCADN, OC4PADN, FAADN,
In order to investigate the electroluminescence (EL)
performance of these new blue emitting materials (excluding
FAADN, which were spectroscopically unsatisfactory), four
nonꢀdoped devices were fabricated by vacuum thermal
deposition with the configuration of ITO/ PEDOT: PSS (50
nm)/ NPB (60 nm)/ ADNs (40 nm)/ TPBI (20 nm)/ LiF/ Al.
Here, TIO was used as an anode electrode and the LiF/Al layers
were employed as a composite cathode. Poly(3,4ꢀethylene
dioxythiophene)/ poly(styrenesulfonate) (PEDOT: PSS) was
used as the holeꢀinjection layer, 4,4’ꢀbis[Nꢀ(1ꢀnaphthyl)ꢀNꢀ
phenylꢀ1ꢀamino]ꢀbiphenyl (NPB) as the holeꢀtransporting layer,
FA3PADN and FA4PADN, which were Cꢀ2 modified ADN
derivatives, exhibited high Td (corresponding to 5% weight
loss) of 408, 492, 407, 423, 495 °C, respectively. The values of
Td of OC4PADN
than that of OCADN and FAADN, which is attributed to the
presence of more aromatic rings in the molecule of OC4PADN
, FA3PADN and FA4PADN are much higher
,
FA3PADN and FA4PADN. Due to the largeꢀvolume
Fig. 2 TGA curves of all ADN derivatives.
4 | J. Name., 2012, 00, 1-3
Fig. 3 Energyꢀlevel diagram of the materials used in devices.
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Table. 2 Characteristics of OLEDsa
ADN
derivatives
Turnꢀon
Voltageb (V)
Max. luminancec
(cd/m2)
Max. efficiencyc
(cd/A, lm/W)
λEL, FWHMd (nm)
CIE(x,y)e
FA3PADN
FA4PADN
OCADN
4.5
4.1
5.1
5.6
4369
4490
5839
3146
1.14, 0.65
1.43,0.85
2.25, 1.13
0.99, 0.48
487, 76
486, 65
477, 62
451, 53
(0.18, 0.33)
(0.17, 0.39)
(0.16, 0.30)
OC4PADN
(0.16, 0.14)
b
c
aITO/ PEDOT: PSS (50 nm)/ NPB (60 nm)/ ADNs (40 nm)/ TPBI (20 nm)/ LiF/ Al. Turnꢀon voltage at 1 cd/m2. Maximum values.
dMaximum EL emission peak and fullꢀwidthꢀatꢀhalfꢀmaximum were recorded at 8.0 V. Commission Internationale d’ Énclairage
e
(CIE) at 6.0 V.
and 2,2’,2’’ꢀ(1,3,5ꢀbenzinetriyl)ꢀtris(1ꢀphenylꢀ1Hꢀbenzimidaꢀ ADN derivatives are matched with the NPB and TPBI, which
zole) (TPBI) as the electronꢀtransporting layer and the holeꢀ reduced the energy barrier between hole/electron transporting
blocking layer. The structures and the energy levels of the layer and emitting layer, and then profited the hole and electron
materials used in these devices are demonstrated in Fig. 3 and transporting and recombination in emitting layer. Fig. 4 (b)
the key performance data were summarized in Table. 2. depicted the luminance versus voltage (LꢀV) of the devices.
The current densityꢀvoltage (
JꢀV) curve of these four devices The device which used OCADN as emitting material showed a
is displayed in Fig. 4 (a). As we can see, the turnꢀon voltages maximum brightness of 5839 cd/m2 at 10 V, FA3PADN
,
were range from 4.1 to 5.6 eV. The primary reason for the low FA4PADN and OC4PADN have maximum luminance 4369,
turnꢀon voltage is that the HOMO and LUMO energy level of 4490 and 3146 cd/m2, respectively. Fig. 5 (a) and (b) presented
Fig. 4 (a) Current densityꢀvoltage characteristics and (b)
Fig. 5 (a) Current efficiency and (b) Power efficiency of the
Luminanceꢀvoltage characteristics of the four devices.
four device.
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note that there is almost no EL color shift vary different driving
voltages for all devices, it demonstrated that the holeꢀelectron
pairs for recombination were well confined in the blue emitter
layer. The EL spectra of these four devices under different
driving voltages were shown in the (ESI†).
Experimental
Materials
All starting materials were purchased from J & K Chemical Co.,
Aladdin Chemical Co. and Shanghai Taoe chemical technology
Co., Ltd. without further purification. Solutions were carefully
dried and distilled from appropriate drying agents prior to use.
All reactions and manipulations were carried out under N2
atmosphere. Silica gel (300ꢀ400 mesh) column chromatography
was used as the stationary phase in the column.
Fig. 6 EL spectra of the four devices.
the current efficiency (IE) and luminousefficiency (LE) of the
fabricated devices. Among the four devices, the OCADN based
device exhibited most efficient performance with current
efficiency of 2.25 cd/A with power efficiency of 1.13 lm/W, it
mainly attributed to its lowest LUMO energy level and the
smallest energy barrier between OCADN and TPBI among
these four compounds, which was helpful for electron
transporting. Meanwhile, its relative lower HOMO energy level
was also reduced the barrier between holeꢀtransporting layer
and emitting layer and beneficial for hole transporting. The
devices with these four materials, especially the OCADN,
showed high maximum brightness, maximum current and
power efficiency. It indicated that the incorporation of
florenamine or indenocarbazole moiety was helpful for improve
the device performance. And it was worthwhile to note that all
four devices showed a near flat current efficiency versus
current density response, which indicated that the hole
transporting nature of indenocarbazole and fluorenamine unit
could reduce the efficiency rollꢀoff and enhance the EL
performance of device.
1
The H NMR and 13C NMR spectra were measured using a
Bruker AM 400 spectrometer. The mass spectra were obtained
on a Waters LCT Premier XE spectrometer. The ultraviolet–
visible (UVꢀVis) absorption spectra of the samples were
characterized using a Varian Cary 500 spectrophotometer.
Photolumineꢀscence (PL) measurements were conducted by a
VarianꢀCary fluorescence spectrophotometer at room
temperature. The cyclic voltammetry experiments were
performed by a Versastat II electrochemical workstation
(Princeton applied research) using a conventional threeꢀ
electrode configuration with a glassy carbon working electrode,
a Pt wire counter electrode, and a regular calomel reference
electrode in saturated KCl solution, 0.1 M tetrabutylammonium
hexafluorophosphate (TBAPF6) in dichloromethane solution as
the supporting electrolyte with a scan rate of 100 mV/s. The
E1/2 values were determined by (Epa + Epc)/2 using Ferrocene as
an external standard, where Epa and Epc were the anodic and
catholic peak potentials, respectively. Thermo gravimetric
analysis was carried out using a TGA instrument under a
nitrogen atmosphere with a heating scan rate of 10 °C/min.
From the EL spectra shown in Fig. 6, we can know that all of
these devices exhibited blue emissions with maximum emission
peaks at 486, 487, 477, 451 nm and the corresponding CIE
coordinates of devices were (0.18, 0.33), (0.17, 0.39), (0.16,
0.30) and (0.16, 0.14) at 8.0 V, respectively. The devices with
our four materials maintained good EL emission in the blue
region spectrum, which suggested that the red shifting were
effectively suppressed when these materials used as emitter to
devices. In accordance with the solid state PL emission, the
device of OC4PADN and OCADN exhibited deeper blue EL
compared with FA3PADN and FA4PADN. It could be
attributed to the larger steric hindrance between the rigid and
coꢀplanar indenocarbazole unit and the ADN core, which
reduced the coplanarity and π conjugation between the two
moieties. Moreover, the device using OC4PADN as emitter
showed the most deepꢀblue emission with the CIE(x,y) of (0.16,
0.14) at 8.0 V, due to the more twisty configuration of
OC4PADN which incorporation a phenyl ring between the
donor and the anthracene core. Furthermore, it was worthing to
Synthesis
The synthesis of intermediates and ADN derivatives (FAADN
OCADN FA3PADN FA4PADN OC4PADN) are presented
in Schemes. 1 and 2.
,
,
,
,
Synthesis of 2-((3-bromophenyl)(phenyl)methyl)-9,9-dimethyl-
9H-fluorene (3).
A mixture of 1ꢀbromoꢀ3ꢀiodobenzene(4.23 g, 0.015 mol), 9,9ꢀ
dimethylꢀNꢀphenylꢀ9Hꢀfluorenꢀ2ꢀamine (2.85 g, 0.01 mol),
potassium hydroxide (2.81 g, 0.05 mol), cuprous iodide (0.095
g, 0.5 mmol) and orthophenanthrolene (0.09 g, 0.5 mmol) in
1,3,5ꢀtrimethylbenzene (80 ml) was stirred at 170 °C for 8 h
under nitrogen atmosphere. After cooling to room temperature,
the solution was evaporated to dryness under reduced pressure.
The cold water was then added to the mixture and finally
extracted with DCM. The combined organic phase was
collected, filtered and dried over MgSO4. The subjection of the
crude mixture to silica gel chromatography using petroleum
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

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View ArticAle ROnTliInCeLE
Journal Name
DOI: 10.1039/C5RA11715A
A mixture of 9,9ꢀdimethylꢀNꢀphenylꢀ9Hꢀfluorenꢀ2ꢀamine (0.3
g, 1.05 mmol), 2ꢀbromoꢀ9,10ꢀdiꢀ(naphthalenꢀ2ꢀyl)anthracene
(0.53 g, 1.05 mmol), potassium tertꢀbutoxide (0.14 g, 1.26
mmol), palladium acetate (0.01 g, 0.05 mmol) and 2ꢀ
dicyclohexyl phosphinoꢀ2',4',6'ꢀtriisopropylbiꢀphenyl (Xphos,
0.036 g, 0.11 mmol) was dissolved in 1,3,5ꢀtrimethylbenzene
(30 mL) and heated at 170 °C for 8 h under nitrogen. After
cooling, the solution removed under reduced pressure. Then the
water was poured into the mixture and extracted with DCM.
The organic layer was collected, filtered and dried by MgSO4,
the crude product was further purified by column
chromatography using petroleum ether/dichloromethane (4:1,
ether/ dichloromethane (4:1, v/v) afforded 3 (2.43 g, yield: 55.4
%) as milky white solid. H NMR (400 MHz, DMSO) δ 7.77
1
(m,
J
= 10.6, 7.4 Hz, 2H), 7.52 (d,
J
J
= 6.8 Hz, 1H), 7.39ꢀ7.34
= 8.0 Hz, 1H), 7.17ꢀ7.08
(m, 2H), 7.34ꢀ7.26 (m, 3H), 7.22 (t,
(m, 4H), 7.06ꢀ6.99 (m, 2H), 6.97ꢀ6.92 (m, 1H), 1.37 (d,
Hz, 6H).
J = 7.2
Synthesis of 9,9-dimethyl-N-phenyl-N-(3-(4,4,5,5-tetramethyl-
1,3,2-dioxabo- rolan-2-yl)phenyl)-9H- fluoren-2- amine (4).
50 ml of anhydrous 1,4ꢀdioxane was added to a mixture of 3
(1.09 g, 2.5 mmol), bis(pinacolato) diboron(0.95 g, 3.75 mmol),
potassium acetate (0.74 g, 7.5 mmol), [1,1'ꢀBis(diphenylꢀ
phosphino) ferrocene]palladium(II) dichloride (Pd(dppf)Cl2)
(Catalytic amount). The reaction mixture was stirred at 100 °C
for 2 h under nitrogen atmosphere. After the reaction was
worked up by adding water, the organic layer was extracted
with DCM and solution was evaporated. The crude product was
purified by column chromatography using petroleum ether/
dichloromethane (5:1 v/v) as eluent. Afforded 4 (0.88 g, yield:
v/v). Finally afforded FAADN (0.32 g, yield: 42.6 %) as yellow
1
solid. H NMR (400 MHz, DMSO) δ 8.20 (d,
8.14ꢀ8.04 (m, 3H), 7.90ꢀ7.77 (m, 4H), 7.73 (d,
J
J
= 8.4 Hz, 1H),
= 7.2 Hz, 1H),
7.70ꢀ7.61 (m, 4H), 7.59ꢀ7.51 (m, 3H), 7.48ꢀ7.40 (m, 3H), 7.38ꢀ
7.13 (m, 9H), 7.10 (s, 1H), 7.03 (d, = 7.6 Hz, 2H), 6.95 (m,
2H), 1.17 (d,
= 15.8 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ
J
J
1
153.58, 147.21, 146.71, 144.75, 138.98, 136.90, 136.02,
134.93, 133.41, 132.76, 132.43, 131.00, 130.21, 129.54,
129.06, 128.11, 127.60, 126.68, 126.23, 125.30, 124.41,
123.77, 122.45, 120.61, 119.49, 119.08, 117.71, 46.71, 26.94,
26.87. HRMS (ESI, m/z): [M+H]+ calcd for C55H40N, 714.3161,
found 714.3167.
72.0 %) as white solid. H NMR (400 MHz, DMSO) δ 7.72 (d,
J
= 8.2 Hz, 2H), 7.50 (d,
J
= 7.2 Hz, 1H), 7.39ꢀ7.29 (m, 6H),
= 2.0 Hz, 1H), 7.14 (m, 1H), 7.06
7.29ꢀ7.24 (m, 1H), 7.20 (d,
J
(m, 3H), 6.91 (m, 1H), 1.35 (s, 6H), 1.24 (s, 12H).
Synthesis of 2-((4-bromophenyl)(phenyl)methyl)-9,9-dimethyl-
9H-fluorene (5).
Compound 5 (2.15 g, yield: 49.0 %) was synthesized as a white
solid in a similar manner of 3 with 1ꢀbromoꢀ4ꢀiodobenzene
Synthesis of 5-(9,10-di(naphthalen-2-yl)anthracen-2-yl)-7,7-di-
methyl-5,7-dihydroindeno[2,1-b]carbazole (OCADN).
instead of 1ꢀbromoꢀ3ꢀiodobenzene. 1H NMR (400 MHz, OCADN (0.17 g, yield: 54.0 %) was synthesized as a yellow
1
DMSO) δ 7.74 (m, 2H), 7.51 (d,
J
= 6.8 Hz, 1H), 7.46ꢀ7.40 (m, solid in a similar manner of FAADN with 2 instead of 1. H
2H), 7.36ꢀ7.29 (m, 3H), 7.28 (m, 1H), 7.24 (m, 1H), 7.11ꢀ7.03 NMR (400 MHz, CDCl3) δ 8.33 (d,
J
= 8.0 Hz, 1H), 8.19ꢀ7.96
(m, 9H), 7.91ꢀ7.84 (m, 2H), 7.84ꢀ7.58 (m, 8H), 7.49 (m, 3H),
7.43ꢀ7.29 (m, 6H), 7.28ꢀ7.26 (m, 1H), 7.23 (d, = 7.0 Hz, 1H),
1.57 (s, 6H). 13C NMR (101 MHz, CDCl3) δ 153.38, 141.27,
(m, 3H), 6.97 (m, 1H), 6.95ꢀ6.89 (m, 2H), 1.36 (s, 6H).
Synthesis of 9,9-dimethyl-N-phenyl-N-(4-(4,4,5,5-tetramethyl-
1,3,2-dioxabor- olan-2-yl)phenyl)-9H- fluoren-2-amine (6).
J
Compound 6 (1.07 g, yield: 87.7 %) was synthesized as a white 139.94, 137.52, 137.01, 136.59, 133.53, 132.90, 132.36,
solid in a similar manner of 4 with 5 instead of 3. 1H NMR (400 130.73, 130.22, 129.66, 128.79, 128.25, 127.99, 127.12,
MHz, CDCl3) δ 7.70ꢀ7.65 (m, 2H), 7.65ꢀ7.62 (m, 1H), 7.58 (d, 126.58, 125.62, 125.01, 124.65, 123.62, 122.96, 122.53,
J
= 8.2 Hz, 1H), 7.41ꢀ7.37 (m, 1H), 7.29 (m, 3H), 7.25ꢀ7.19 (m, 120.08, 119.34, 111.29, 109.91, 103.99, 53.46, 46.80, 27.98.
2H), 7.15 (m, 2H), 7.12ꢀ7.05 (m, 3H), 7.03 (m, 1H), 1.41 (s, HRMS (ESI, m/z): [M+H]+ calcd for C55H38N, 712.3004, found
6H), 1.34 (s, 12H). 712.3000.
Synthesis of 5-(4-bromophenyl)-7,7-dimethyl-5,7-dihydroindeno Synthesis
[2,1b] carbazole (7). phenyl)-9,9-dimethyl-N-phenyl-9H-fluoren-2-amine (FA3PADN).
of
N-(3-(9,10-di(naphthalen-2-yl)anthracen-2-yl)
Compound 7 (2.78 g, yield: 63.7 %) was synthesized as a white 2ꢀbromoꢀ9,10ꢀdi(naphthalenꢀ2ꢀyl)anthracene (0.38 g, 0.75 mmol), 4
solid in a similar manner of 3 with 2 instead of 1. 1H NMR (400 (0.25 g, 0.5 mmol), 2M aqueous potassium carbonate (10 mL)
MHz, CDCl3) δ 8.43 (d,
J = 0.6 Hz, 1H), 8.19 (d, J = 7.8 Hz, was added to the 20 mL anhydrous tetrahydrofuran. After
1H), 7.85 (d, = 7.4 Hz, 1H), 7.81ꢀ7.73 (m, 2H), 7.54ꢀ7.46 (m, tetrakis(triphenylphosphine)palladium(0) (Pd(PPh3)4) (Catalytic
J
2H), 7.45ꢀ7.26 (m, 7H), 1.51 (s, 6H).
amount) was added to the mixture, it was stirred under reflux
for 4 h under nitrogen atmosphere. The reaction mixture was
poured into water, and the aqueous solution was extracted with
DCM. The extracts were washed with water and dried over
magnesium sulfate. After the solution was evaporated, the
crude product was purified by silica gel chromatography using
petroleum ether/dichloromethane (4:1, v/v). Afforded
Synthesis of 7,7-dimethyl-5-(4-(4,4,5,5-tetramethyl-1,3,2-dioxa-
borolan-2-yl) phenyl)-5,7-dihydroindeno [2,1-b] carbazole (8).
Compound 8 (0.85 g, yield: 70.2 %) was synthesized as a white
solid in a similar manner of 4 with 7 instead of 3. 1H NMR (400
MHz, CDCl3) δ 8.43 (s, 1H), 8.19 (d,
J
= 7.8 Hz, 1H), 8.10 (d,
= 8.6 Hz, 1H), 7.63 (t, = 8.8 Hz, 2H),
= 6.8 Hz, 2H), 1.50 (s, 6H), 1.41 (s,
J
= 8.0 Hz, 2H), 7.84 (t,
7.40 (m, 5H), 7.29 (q,
12H).
J
J
J
1
FA3PADN (0.25 g, yield: 62.5 %) as yellow solid. H NMR
(400 MHz, CDCl3) δ 8.10ꢀ7.87 (m, 6H), 7.83 (m, 3H), 7.71ꢀ
7.59 (m, 3H), 7.59ꢀ7.47 (m, 7H), 7.44 (d,
J = 8.2 Hz, 1H), 7.38
Synthesis of N-(9,9-dimethyl-9H-fluoren-2-yl)-9,10-di(naphtha-
len-2-yl)-N-phenylanthracen-2-amine (FAADN).
(m, 1H), 7.29 (d, = 7.2 Hz, 1H), 7.25ꢀ7.19 (m, 4H), 7.18ꢀ7.13
J
(m, 1H), 7.10 (m, 2H), 7.07ꢀ6.96 (m, 5H), 6.92 (m, 2H), 6.84
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 7

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ARTICLE
RSC Advances
VJieowuArrtnicalelONnlainme e
DOI: 10.1039/C5RA11715A
(m, 1H), 1.29 (t,
J
= 5.1 Hz, 6H). 13C NMR (101 MHz, CDCl3)
Conclusions
δ 152.51, 147.37, 145.99, 141.01, 137.92, 136.33, 132.42,
131.78, 129.26, 128.47, 128.10, 127.01, 126.06, 125.90,
125.43, 125.22, 124.19, 123.37, 123.14, 122.56, 121.77,
121.43, 121.22, 120.20, 119.56, 118.42, 117.91, 45.75, 26.01.
HRMS (ESI, m/z): [M+H]+ calcd for C55H38N, 790.3474, found
790.3470.
In summary, we have synthesized and characterized a series of
ADN derivatives, FAADN OCADN FA3PADN FA4PADN
,
,
,
and OC4PADN. Expect for FAADN, the other four materials
exhibited satisfactory blue fluorescence emission both in
toluene and solid film, which attributed to the sterically
hindered substituent at Cꢀ2 position of ADN. These compounds
also showed excellent thermal properties and appropriate
energy levels, which can be utilized as emitting materials for
OLED device. As a result, a device base on OCADN with the
structure of ITO/ PEDOT: PSS/ NPB/ ADNs/ TPBI/ LiF/ Al
showed efficient blue emission peaked at 477 nm and CIE
chromaticity coordinates of (0.16, 0.30). The maximum current
efficiency and power efficiency of the device reached 2.25 cd/A
and 1.13 lm/W, respectively.
Synthesis of 9,9-dimethyl-N-phenyl-N-(4-(4,4,5,5-tetramethyl-1,
3,2-dioxaborolan-2-yl)phenyl)-9H-fluoren-2-amine (FA4PADN).
FA4PADN (0.17 g, yield: 54.0 %) was synthesized as a yellow
1
solid in a similar manner of FA3PADN with 6 instead of 4. H
NMR (400 MHz, CDCl3) δ 8.10 (m, 2H), 8.07ꢀ7.99 (m, 4H),
7.98ꢀ7.89 (m, 3H), 7.81 (d,
7.69ꢀ7.64 (m, 2H), 7.60 (m, 6H), 7.55 (d,
(t, = 8.0 Hz, 3H), 7.32ꢀ7.27 (m, 3H), 7.22 (d,
7.17 (d, = 2.0 Hz, 1H), 7.11 (d, = 7.6 Hz, 2H), 7.07 (d, J =
J
= 9.2 Hz, 1H), 7.77ꢀ7.70 (m, 2H),
= 8.2 Hz, 1H), 7.38
= 7.4 Hz, 3H),
J
J
J
J
J
8.6 Hz, 2H), 7.01 (m, 2H), 1.38 (s, 6H). 13C NMR (101 MHz,
CDCl3) δ 155.10, 147.67, 147.40, 138.92, 137.12, 136.60,
134.45, 133.49, 132.83, 130.56, 130.07, 129.67, 129.27,
127.92, 127.04, 126.96, 126.28, 125.27, 124.39, 123.75,
123.48, 122.92, 122.46, 120.64, 119.46, 119.01, 46.83, 27.07.
HRMS (ESI, m/z): [M+H]+ calcd for C55H38N, 790.3474, found
790.3476.
Acknowledgements
Q. Dong thanks the financial support from the National Natural
Science Foundation of China (Grant No.: 61307030), Program
for the Outstanding Innovative Teams of Higher Learning
Institutions of Shanxi (OIT), Fund Program for the Scientific
Activities of Selected Returned Overseas Professionals in
Shanxi Province, the Natural Science Foundation for Young
Scientists of Shanxi Province, China (Grant No.: 2014021019ꢀ
2), the Outstanding Young Scholars Cultivating Program,
Research Project Supported by Shanxi Scholarship Council of
China (Grant No.: 2014ꢀ02) and the Qualified Personal
Foundation of Taiyuan University of Technology (Grant No.:
2013Y003, tyutꢀrc201275a).
Synthesis of 7,7-dimethyl-5-(4-(4,4,5,5-tetramethyl-1,3,2-dioxa-
borolan-2-yl)phenyl)-5,7-dihydroindeno carbazole (OC4PADN).
OC4PADN (0.18 g, yield: 32.0 %) was synthesized as a white
1
solid in a similar manner of FA3PADN with 8 instead of 4. H
NMR (400 MHz, CDCl3) δ 8.42 (s, 1H), 8.16 (t,
3H), 8.12ꢀ8.04 (m, 5H), 7.99 (d, = 4.2 Hz, 2H), 7.92 (d,
9.2 Hz, 1H), 7.84 (d, = 7.4 Hz, 1H), 7.81ꢀ7.68 (m, 7H), 7.65
(m, 4H), 7.59 (d, = 8.6 Hz, 2H), 7.44ꢀ7.32 (m, 7H), 7.28 (m,
J = 8.4 Hz,
J
J =
J
J
2H), 1.49 (s, 6H). 13C NMR (101 MHz, CDCl3) δ 155.02,
153.58, 147.21, 146.71, 144.75, 138.98, 136.90, 134.93,
134.72, 133.41, 133.12, 132.76, 132.43, 131.00, 130.49,
130.21, 129.06, 126.90, 126.23, 125.30, 123.77, 122.76,
122.45, 120.61, 119.49, 119.08, 117.71, 46.71. HRMS (ESI,
m/z): [M+H]+ calcd for C55H38N, 788.3317, found 788.3313.
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J. Name., 2012, 00, 1-3 | 9