Dinuclear cyclometalated iridium (III) complex containing functionalized triphenylamine core: synthesis, photophysics and application in the single-emissive-layer WOLEDs

Article abstract of DOI:10.1016/j.tet.2016.09.012

To obtain highly efficient white-emitting devices, a novel functionalized dinuclear iridium (III) complex of C₈TPA(FIrpic)₂was successfully synthesized and characterized. In this phosphor, FIrpic is a blue-emitting phosphorescent chr

Full text of DOI:10.1016/j.tet.2016.09.012

Accepted Manuscript
Dinuclear cyclometalated iridium(III) complex containing functionalized triphenylamine
core: synthesis, photophysics and application in the single-emissive-layer WOLEDs
Keqi He, Ning Su, Yu Liu, Wenjing Xiong, Zhaoran Hao, Dongge Ma, Weiguo Zhu
PII:
S0040-4020(16)30919-X
10.1016/j.tet.2016.09.012
TET 28083
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 23 July 2016
Revised Date: 7 September 2016
Accepted Date: 9 September 2016
Please cite this article as: He K, Su N, Liu Y, Xiong W, Hao Z, Ma D, Zhu W, Dinuclear cyclometalated
iridium(III) complex containing functionalized triphenylamine core: synthesis, photophysics and
application in the single-emissive-layer WOLEDs, Tetrahedron (2016), doi: 10.1016/j.tet.2016.09.012.
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ACCEPTED MANUSCRIPT
Graphical abstract
Dinuclear Cyclometalated Iridium(III) Complex Containing Functionalized
Triphenylamine Core: Synthesis, Photophysics andApplication in the
Single-Emissive-Layer WOLEDs
Keqi He b,&, Ning Su b,&, Yu Liu b*, Wenjing Xiong a,b, Zhaoran Hao b,
Dongge Ma c* and Weiguo Zhu a,b*
a School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of
Photovoltaic Science and Engineering, Changzhou University, Changzhou 213164, China
b College of Chemistry, Key Lab of Environment-Friendly Chemistry and Application of the Ministry of
Education, Xiangtan University, Xiangtan 411105, China
c State Key Laboratory of Luminescent Materials and Devices, South China University of Technology,
Guangzhou 510640, China
& Both authors contribute equally to this work.
A novel triphenylamine-functionalized dinuclear iridium (III) complex of C8TPA(FIrpic)2
was synthesized and characterized. White emission with a rising brightness of 1770 cd/m2
and current efficiency of 1.31cd/A was obtained in the single-emissive-layer OLEDs with
a configuration of ITO/PEDOT:PSS/C8TPA(FIrpic)2 (10 wt %):TCTA/ TPBi/LiF/Al using
C8TPA(FIrpic)2 as a single-component emitter.

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Dinuclear Cyclometalated Iridium (ꢀ) Complex Containing
Functionalized Triphenylamine Core: Synthesis, Photophysics and
Application in the Single-Emissive-Layer WOLEDs
Keqi He b, &, Ning Su b, &, Yu Liu b,*, Wenjing Xiong a,b, Zhaoran Hao b,
Dongge Ma c,* and Weiguo Zhu a, b
*
a School of Materials Science and Engineering, Jiangsu Collaborative Innovation
Center of Photovoltaic Science and Engineering, Changzhou University,
Changzhou 213164, China
bCollege of Chemistry, Key Lab of Environment-Friendly Chemistry and Application
of the Ministry of Education, Xiangtan University, Xiangtan 411105, China
c State Key Laboratory of Luminescent Materials and Devices, South China University
of Technology, Guangzhou 510640,China
& Both authors contribute equally to this work.
*To whom correspondence should be addressed Email:
(W. Z.) zhuwg18@126.com
(Y. L.) liuyu03b@126.com
(D. M.) mdg1014@ciac.jl.cn
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ABSTRACT: To obtain highly efficient white-emitting devices, a novel functionaliz
-ed dinuclear iridium (III) complex of C8TPA(FIrpic)2 was successfully synthesized
and characterized. In this phosphor, FIrpic is a blue-emitting phosphorescent chromo-
phore of iridium(III) bis[(4,6-difluorophenyl)pyridinato-N,C2'] picolate and C8TPA is
a blue-emitting fluorescent chromophore of triphenylamine as bridging donor. Its opto-
physical and electro-phosphorescent properties were primarily investigated. White
emission with an increasing current efficiency of 1.31cd/A at 15.3 mA/cm2 and
brightness of 1770 cd/m2 at 656.3 mA/cm2 was obtained in its single-emissive-layer
OLEDs with a configuration of ITO/PEDOT:PSS/C8TPA(FIrpic)2 (10 wt %):TCTA/
TPBi/LiF/Al. The results indicate that an introduction of triphenylamine group into
dinuclear iridium (III) complexes as bridged donor can improve the performance of its
iridium (III) complexes-doped OLEDs.
Keywords: White-light-emitting; Dinuclear iridium (III) complex; Triphenylamine;
WOLEDs; Electroluminescence; Synthesis
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1. Introduction
In the past few decades, white organic light-emitting diodes (WOLEDs) have
drawn much attention due to their potential applications in full color displays, back
lighting of flat-panel displays and solid-state lighting.1-5 Usually, WOLEDs were
fabricated with different emissive materials in a single or multiple emission layers by
co-evaporation or consecutive evaporations.6-7 However, the strategy of mixing
different emissive materials usually results in complicated processes, expensive cost
and unstable device performance. To overcome the above defects, WOLEDs using
single emissive dopant in single emissive layer (SEL) have been emerged because of
their simple fabrication.8-11 As iridium (III) complexes possess unique octahedral
structure, relatively short excited-state lifetime, as well as high photoluminescence
efficiency, up to now, WOLEDs and white polymer light-emitting devices (WPLEDs)
based on various iridium (III) complexes had been made certain progress.12-17
However, few reports on the iridium (III) complex in the SEL WOLEDs and
WPLEDs were reported.15-16
Recently, a fluorene-functionalized binuclear iridium (III) complex of (dfppy)4Ir2
-(dipic-FL) was reported by our group,18 and white emission with a maximum lumi-
nance of 1040 cd/m2 and current efficiency of 1.2 cd/A was obtained in its SEL
OLEDs with a configuration of ITO/PEDOT:PSS/ (dfppy)4Ir2(dipic-FL) (10 wt%):
TCTA/TPBi/LiF/Al. Due to low current efficiency and brightness, as well as lumine-
scent annihilation at high current density, the dinuclear iridium (III) complex-based
device do not still meet the practical requirement for application. Therefore, various
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functionalized binuclear iridium (III) complexes need to be developed by incor-
porating carrier-transporting functional groups into their ligands to overcome these
problems.
With this consideration, in this paper, we reported our effort to obtain a function-
alized dinuclear iridium (III) complex by incorporating a triphenylamine (TPA) group
into its ligand and get high-efficiency near white-emitting OLEDs. The designed
functional dinuclear iridium (III) complex of C8TPA(FIrpic)2 with an acceptor-
donor-acceptor (A-D-A) structure, where FIrpic unit as an acceptor unit can generate
a strong blue emission,9-10 and C8TPA i.e. 4-(octyloxymethyl)-N,N-diphenyl-benzene
-amine is used as donor and bridged unit. The synthetic route is shown in Scheme 1
and its opto-physical properties were studied. C8TPA is designed as a bridge unit in
dinuclear iridium (III) complex based on the following considerations. First, incorpo-
rating a hole-transporting TPA group instead of fluorene (FL) unit,18 into both
chromophores of iridium (III) complexes is available to improve its carrier-
transporting property.19-21 Second, the non-planar TPA unit is favorable for suppress
-ing molecular aggregation owing to its bulk space effect.21 Third, TPA inserted
between two acceptor units as a bridged donor can build an A-D-A framework and
result in a long wavelength emission via intramolecular charge transfer (ICT).18 Mean
-while, incorporating an octyl chain can increase solubility of iridium (III) complex.
Compared to (dfppy)4Ir2(dipic-FL), C8TPA(FIrpic)2 should have an obvious advan-
tage to get a higher white light-emitting efficiency in their doped devices. As expected,
in the SEL-based OLED using C8TPA(FIrpic)2 as a single-component emitter at 10
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wt% dopant concentration, white emission was observed with a maximum luminance
of 1770 cd/m2 and an increasing current efficiency of 1.31 cd/A. Accordingly,
introducing hole-transporting TPA unit into the dinuclear iridium (III) complex is
responsible for the improved device performance. To our knowledge, this is one of
the best examples in term of dinuclear iridium (III) complex as single dopant in the
high-performance white-emitting SEL-OLEDs.
Scheme 1. Synthetic route of C8TPA(FIrpic)2.
2. Synthesis and characterization
As shown in Scheme 1, compounds of 1, 3, 4 and 5 were synthesized according to
the literature procedures.18,19 Iridium (III) complex of FIrpic-Br was prepared based
on the reported article.18 C8TPA(FIrpic)2 was obtained via Suzuki coupling reaction
1
using a catalyst of Pd(PPh3)4 in a moderate yield of 56%. It was confirmed with H
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13
NMR, C NMR and MALDI-TOF mass spectrometry, as well as elemental analysis
(see Electron Supporting Information, ESI).
3. Photophysical properties
The UV-vis absorption spectra of the dinuclear iridium (III) complex and its
parent FIrpic were measured in dichloromethane (DCM) solution at room temperature
(RT) and are depicted in Fig. 1. Their corresponding data are illustrated in Table 1.
Two obvious peaks at 258 and 391 nm are observed in the DCM solution of C8TPA-
(FIrpic)2. The high-lying absorption is assigned to the spin-allowed ligand-central (LC)
π-π* transition of FIrpic chromophore. And the low-lying absorption is attributed to
the intramolecular charge transfer (ICT) transition from the TPA unit to the FIrpic
chromophore, to some extend metal-ligand charge transfer (MLCT) transition. Com-
pared to the parent FIrpic, C8TPA(FIrpic)2 exhibits a significantly enhanced low-lying
absorption with higher molar absorption coefficient, implying that the ICT effect play
-s an important role in enhancing absorption due to an incorporation of TPA unit.
Fig. 1. Normalized UV-vis absorption spectra of FIrpic and C8TPA(FIrpic)2
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in dilute DCM(10-5 M) at RT.
The PL spectra of C8TPA(FIrpic)2 and FIrpic in dilute DCM and in their neat films
at RT are displayed in Fig. 2. And their corresponding photophysical data are summa-
rized in Table 1. Two intense emission peaks at 465 nm and 542 nm with a long
wavelength shoulder about 600 nm are observed in C8TPA(FIrpic)2. Compared the PL
spectrum of FIrpic, the high-lying emission peak at 465 nm is assigned to the mixed
spin-allowed and spin-forbidden singlet MLCT transitions in FIrpic chromophore.
The low-lying emission at 542 nm is attributed to the ICT effect from the TPA to
FIrpic chromophore. It is further found that the intensity for this low-lying emission is
enhanced with increasing C8TPA(FIrpic)2 concentrations from 2 × 10-4 to 2 × 10-3 M
Fig. 2. Normalized PL spectra of FIrpic and C8TPA(FIrpic)2 in DCM (10-5 M) and
their neat films at RT.
in Fig. S9 (see ESI). It is worth noting that C8TPA(FIrpic)2 shows an obvious red-
shift PL spectrum comparing with (dfppy)4Ir2(dipic-FL) in dilute DCM, which is
ascribed to the increasing conjugated system and ICT effect. However, C8TPA-
(FIrpic)2 exhibits a remarkably blue-shifted one in its film. The similar phenomenon
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was observed in (dfppy)4Ir2(dipic-FL), which is owing to the motional relaxation of
the excited state geometry.18
4. Thermal property
The thermal stability was characterized by thermogravimetric analysis (TGA) at a
scanning rate of 20 °C/min under a nitrogen atmosphere, and the TGA curve of
C8TPA(FIrpic)2 and FIrpic are shown in Fig. 3. High decomposition temperatures (Td)
of 362 and 337 °C are observed at a 5% weight loss, respectively. It indicates this
dinuclear iridium (III) complex with an incorporating TPA functional group presents
an enhancing thermal stability.
Fig. 3. TGA curve of C8TPA(FIrpic)2 at a scanning rate of 20 oC/min.
5. Electrochemical property
The oxidation properties of C8TPA(FIrpic)2 was calculated by cyclic voltammetry
(CV) method using ferrocene as an internastandard.18, 22 An irreversible oxidation
wave (Eox) at 1.06 V is observed versus Fc/Fc+ in Fig. 4. According to the Eox and the
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onset of UV/vis absorption spectrum in the film, the highest occupied molecular
orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels
(EHOMO and ELUMO) of C8TPA(FIrpic)2 can be calculated based on the following
opt
empirical formula: Eg =1240/λedge = Eox - Ered = EHOMO - ELUMO, EHOMO = - (Eox
+
4.41).23 As a result, the EHOMO and ELUMO values are -5.47 eV and -2.77 eV for
C8TPA(FIrpic)2, respectively. The resulting CV data are summarized in Table 2. Com
-pared to (dfppy)4Ir2(dipic-FL), C8TPA(FIrpic)2 displays a higher HOMO and LUMO
energy level.
Fig. 4. Cyclic voltammetry curve of C8TPA(FIrpic)2.
Table 1. Photophysical, thermal and electrochemical properties of C8TPA(FIrpic)2 and FIrpic.
opt
Complex
UV
aλPL
bλPL
cEred
dEox
eEHOMO
fELUMO
gEg
Td
(nm)
(nm)
(nm)
(V)
(V)
(eV)
(eV)
(eV)
(oC)
258
385
258
391
471
596
489
501
/
/
-5.62
-3.20
2.42
337
FIrpic
465,542
572,623
424,445
480,534,577
-1.64
1.06
-5.47
-2.77
2.70
362
C8TPA(FIrpic)
a PL spectra in DCM (λex = 380 nm); b PL spectra in the neat film (λex = 380 nm); c Ered = Eox- Egoptꢀd Potential
values are obtained by cyclic voltammetry; e EHOMO = -(4.41 + Eox) eV; f ELUMO = EHOMO- Egoptꢀg Egopt = 1240/λedgeꢁ
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6. Electroluminescent property
The electroluminescent (EL) spectra of the C8TPA(FIrpic)2 doped devices in a
dopant concentration of 10 wt% at different driving voltages from 4.8 to 8.8 V are
showed in Fig. 5, and their corresponding CIE chromaticity diagrams are inserted it.
Obviously, these EL emissions at a maximum peak at 535 nm with three shoulders at
433, 475, and 561 nm are observed in the given different voltages. The EL spectra
cover whole visible range from 375 to 750 nm. The emission at 535 nm with the
shoulder at 561 nm is assigned to the ICT transition, to some extend the IL π-π*
excited states. The emission at 475 nm originates from the intrinsic emissions of the
FIrpic groups.24, 25 The emission at 433 nm is attributed to the TCTA host. The CIE c-
Fig. 5. EL spectra and CIE chromaticity diagram of the C8TPA(FIrpic)2-doped device in a 10 wt%
dopant concentration under different applied voltage from 4.8 V to 8.8 V.
hromaticity coordinates vary in a region from (0.39, 0.52) to (0.27, 0.35) under given
driving voltages. It is clear these CIE coordinates are located in the near white regions
of (0.33, 0.33) at the applied voltages from 6.8 V to 8.8 V, indicating this dinuclear
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iridium (III) complex emits near white EL at the situation.. It indicates that novel
dinuclear iridium (III) complex is a promising white-emitting phosphor.
Fig. 6. The J-B-V (a) and J-LE (b) curves of the C8TPA(FIrpic)2-doped device at a 10 wt % dopant
concentration.
Fig. 6a shows the luminance-voltage-current density (L-V-J) curves of the device at
10 wt% dopant concentration. For comparison, the device performances are summa-
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rized in Table 2. A maximum brightness of 1770 cd/m2 at 656.3 mA/cm2 was obtain
-ed in the device, which was 1.7 times value from the (dfppy)4Ir2(dipic-FL)-doped
device with the same device structure. Even at the 100 mA/cm2, the device remained
brightness as high as 728.8 cd/m2.
On the other hand, the turn-on voltage of the device is observed to be 4.7 V. As
shown in Fig. 6b, the device presented a maximum current efficiency of 1.31 cd/A at
15.3 mA/cm2. Distinctly, compared to the (dfppy)4Ir2(dipic-FL), C8TPA(FIrpic)2 has a
higher luminance and current efficiency owing to introduction of the non-planar TPA
unit, which is available to improve carrier-transporting properties and suppress
aggregations. Hence, this work provides a good strategy to design novel dinuclear
cyclometalated iridium (ꢀ) complex with the A-D-A structure to achieve higher-
efficiency white-light-emission.
Table 2. Performance of C8TPA(FIrpic)2-doped device at a 10 wt % dopant concentration
Dopant
Ratioa
(wt%)
Turn-on
Voltage
(V)
Maximum LEb
J = 100 mA/cm2
Maximum Lb
J
LE
L
LE
J
L
(mA/cm2)
(cd/A)
(cd/m2)
(cd/A)
(mA/cm2)
(cd/m2)
10
4.7
15.3
1.31
728.8
0.72
656.3
1770
a The doping 10 wt % of C8TPA(FIrpic)2 in the device with a configuration of ITO/PEDOT: PSS/C8TPA(FIrpic)2
(10 wt %):TCTA/ TPBi/LiF/Al; b The luminance (L) and luminous efficiency (LE) were measured with a silicon
photodiode and calibrated using a PR-705 SpectraScan Spectrophotometer (Photo Research).
7. Conclusions
The synthesis, and photophysical, electrochemical, electroluminescent properties
of C8TPA(FIrpic)2 were investigated. The results have proved that introducing an
A-D-A framework into dinuclear iridium (III) complex is available to get a wide-
spectrum emission. Furthermore, near white emission was observed in the C8TPA-
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(FIrpic)2-doped SEL OLEDs with various applied voltages from 4.8 to 8.8 V. An
creasing luminance of 1770 cd/m2 and current efficiency of 1.31 cd/A as well as a low
turn on voltage of 4.7 V were obtained in the C8TPA(FIrpic)2-doped devices. Our
results demonstrate that grafting suitable bridged donor unit into dinuclear iridium (III)
complex is efficient way to achieve high-efficiency white emission for its dinuclear
iridium (III) complex as single emissive dopant in the SEL OLEDs
8. Experiments
8.1. Methods
1
13
All H and C NMR spectra were obtained using a Bruker Dex-400 NMR instru-
ment using CDCl3 as a solvent. Elemental analysis was performed on a Harrios
elemental analysis instrument. Mass spectra (MS) were recorded on a Bruker
Autoflex MALDI-TOF instrument using dithranol as a matrix. The UV/vis absorption
and photoluminescent spectra were measured with a Varian Cray 50 and Perkin–
Elmer LS50B luminescence spectrometer, respectively. Cyclic voltammetry was
carried out on a CHI 600A electrochemical work station in a 0.1 mol/L tetrabutyl-
ammonium hexafluorophosphate (Bu4NPF6) acetonitrile solution at a 100 mV/s scan
rate under nitrogen protection. The platinum plate, platinum wire and Ag/AgCl
electrode were used as working electrode, counter electrode, reference electrode, res-
pectively. The thermogravimetric analysis (TGA) was performed with a NETZSCH
STA449 from 25 °C to 600 °C at a 20 °C/min heating rate under a nitrogen
atmosphere.
8.2. Device fabrication and characterization
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C8TPA(FIrpic)2 was dissolved in chlorobenzene with a concentration of 4 mg/mL at
room temperature overnight. The hole-injection layer of poly(ethylenedioxy-thio
phene)/poly(styrene-sulfonate) (PEDOT: PSS) was spin-coated on indium tin oxide
(ITO) at 3000 rpm in N2 atmosphere. Then the emitter layer was prepared by spin-
coating onto the PEDOT: PSS layer at 1500 rpm in N2 atmosphere. Finally, 30 nm
electronic-injection layer of TPBi, 1 nm cathode of LiF and 150 nm capping layer of
aluminum were successively deposited on the top of emitting layer through a shadow
mask in vacuum. The fabricated SEL devices have a configuration of ITO/PEDOT:
PSS (40 nm)/C8TPA(FIrpic)2:TCTA (10 wt%) (50 nm)/TPBi (30 nm)/LiF (1 nm)/Al
(150 nm). The emitting layer consisted of the host of TCTA and dopant of C8TPA-
(FIrpic)2. The dopant concentration was 10 wt%. EL spectra were recorded with an
Insta-Spec IV CCD system (Oriel). Luminance was measured with a Si photodiode
and calibrated by using a PR-705 spectrascan spectrophotometer (Photo Research).
8.3. General information
All solvents were carefully dried and distilled prior to use. Commercially available
；
reagents were used without further purification unless otherwise stated. All reactions
were performed under nitrogen atmosphere and were monitored by thin-layer
chromatography. FIrpic-Br and compounds of 3, 4, 5 were synthesized according to
the reported procedures.18-19
8.4. (4-(bis(4-bromophenyl)amino)phenyl)methanol (6)
A mixture of compound 5 (4.12 g, 9.58 mmol) and NaBH4 (0.80 g, 21.00 mL) in
THF (30 mL) and ethanol (30 mL) was stirred at room temperature (RT) under the
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protection of nitrogen atmosphere overnight. Then 20 mL water was added to stop
reaction, the mixing solution was poured into the water (100 mL) and extracted with
DCM (3 × 30 mL). The residue was purified by silica gel column chromatography
using PE/EA (V/V = 1/2) as eluent to gain colorless viscous liquid. (3.30 g, 97.3%).
1H NMR (CDCl3, 400 MHz, TMS), δ (ppm): 7.34 (d, J = 8.5 Hz, 4H), 7.31-7.25 (m,
2H), 7.04 (d, J = 8.2 Hz, 2H), 6.93 (d, J = 8.6 Hz, 4H), 4.65 (s, 2H).
8.5. 4-bromo-N-(4-bromophenyl)-N-(4-(octyloxymethyl)phenyl)benzenamine (7)
A mixture of compound 6 (2.43 g, 5.65 mmol), C8H17Br (5.45 g, 28.30 mmol) and
NaH (1.20 g, 50.00 mmol) in THF (30 mL) was stirred at RT under nitrogen
atmosphere for 48 h. The solution was poured into water (80 mL) and extracted with
DCM (3 × 25 mL). The combined organic layer was washed with brine and dried over
MgSO4. After removal of the solvent by rotary evaporation, the residue was purified
by silica gel column chromatography with PE/DCM (V/V = 1:1) as the eluent to
1
provide compound 7 as colorless viscous liquid (1.95mg, yield 74.1%). H NMR
(CDCl3, 400 MHz, TMS), δ (ppm): 7.33 (d, J = 8.6 Hz, 4H), 7.28-7.21 (m, 2H), 7.02
(d, J = 8.2 Hz, 2H), 6.92 (d, J = 8.5 Hz, 4H), 4.44 (s, 2H), 3.49 (t, J = 6.6 Hz, 2H),
1.64-1.62 (m, 2H), 1.36-1.23 (m, 10H), 0.88 (t, J = 6.7 Hz, 3H).
8.6.N-(4-(octyloxymethyl)phenyl)-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)
-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)benzenamine (8)
A mixture of compound 7 (0.28 g, 0.52 mmol), bis(pinacolato)diboron (0.40 g, 1.30
mmol), potassium acetate ( 0.80 g, 7.62 mmol) and PdCl2(dppf)CH2Cl2 ( 80 mg, 0.09
mmol) in 1,4-dioxane (25 mL) was heated at 75 °C under nitrogen atmosphere over-
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night. After cooled to RT, the mixture was poured into water (100 mL) and extracted
with DCM (3 × 30 mL). The combined organic layer was dried over MgSO4 and then
concentrated under reduced pressure. The residue was purified by silica gel column
chromatography using DCM/PE (V/V = 2/1) as eluent to gain red viscous solid. (93
mg , 79.2%)ꢁ1H NMR (CDCl3, 400 MHz, TMS), δ (ppm): 7.66 (d, J = 7.6 Hz, 4H),
7.24 (m, 2H), 7.06 (m, 6H), 4.45 (s, 2H), 3.52-3.46 (m, 2H), 1.63-1.55 (m, 2H), 1.33
(s, 24H), 1.30-1.22 (m, 10H), 0.90-0.86 (m, 3H).
8.7. C8TPA(FIrpic)2
To a mixture of compound 8 (50 mg, 0.08 mmol), FIrpic-Br (135 mg, 0.18 mmol),
and Pd(PPh3)4 (11 mg) was added a degassed mixture of THF (10 mL), anhydrous
ethanol (1 mL) and 2 M potassium carbonate aqueous solution (1 mL). The mixture
was refluxed for 24 h under the protection of nitrogen. After cooled to RT, the
mixture was poured into 100 mL distilled water. It was extracted with DCM (3 × 30
mL) and the combined organic layer was dried over anhydrous magnesium sulfate.
The solvent was removed off by rotary evaporation and the residue was passed
through a flash silica gel column with THF/DCM (V/V = 1/5) as the eluent to give
1
pale yellow solid (77 mg, yield 56%). H NMR (CDCl3, 400 MHz, TMS), δ (ppm):
8.79 (d, J = 5.0 Hz, 2H), 8.32 (t, J = 9.3 Hz, 4H), 8.25 (d, J = 8.1 Hz, 2H), 8.08 (d, J =
7.9 Hz, 2H), 7.93 (s, 2H), 7.79 (t, J = 7.0 Hz, 4H), 7.50 (d, J = 5.1 Hz, 2H), 7.31 (d, J
= 7.7 Hz, 2H), 7.20-7.24 (m, 6H), 7.15-7.04 (m, 6H), 6.98 (t, J = 6.1 Hz, 2H),
6.53-6.31 (m, 4H), 5.86 (d, J = 7.6 Hz, 2H), 5.57 (d, J = 7.3 Hz, 2H), 4.47 (s, 2H),
3.53 (t, J = 6.3 Hz, 2H), 1.65 (m, 2H), 1.47-1.10 (m, 10H), 0.87 (t, J = 6.3 Hz, 3H).
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13C NMR (CDCl3, 100 MHz, TMS), δ (ppm): 172.84, 166.09, 164.55, 162.67, 160.22,
160.09, 152.61, 151.81, 149.85, 149.07, 148.72, 148.15, 145.59, 140.63, 138.44,
136.06, 135.50, 129.44, 128.97, 128.76, 128.23, 127.94, 126.16, 124.18, 123.66,
123.46, 123.04, 122.85, 122.77, 122.45, 114.94, 114.69, 114.52, 98.36, 98.16, 97.91,
97.64, 72.55, 71.32, 32.01, 29.94, 29.63, 29.44, 26.40, 22.83, 14.25. MALDI-MS
(m/z): 1773.41 for [M]+. MALDI-TOF MS (m/z) for C83H61F8Ir2N7O5, Calcd:
1773.39, Found, 1773.40, 1796.38 [M++Na]. Anal. Calcd for C83H61F8Ir2N7O5: C
56.23, H 3.47, N 5.53% (C 56.17, H 3.43, N 5.36%).
Acknowledgments
Thanks to the financial supports from the National Natural Science Foundation of
China (51273168, 51473140, 21202139), the Program for Innovative Research
Cultivation Team in University of Ministry of Education of China (1337304), Natural
Science Foundation of Hunan (12JJ4019), the Scientific Research Fund of Hunan
Provincial Education Department (12B123), Open Project for the National Key
Laboratory of Luminescent Materials and Devices (2015-skllmd-08), the Scientific
Research Fund of Xiangtan University (11QDZ18, 2011XZX08).
Supporting Information
Supporting information associated with this article can be found in the online
version, at xxxxx.
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Research Highlights
ꢀ
ꢀ
A triphenylamine-functionalized dinuclear iridium complex of C8TPA(FIrpic)2 was
synthesized.
The optophysical and electroluminescent properties of C8TPA(FIrpic)2 were
investigated.
ꢀ
ꢀ
White emission was observed in its doped single-emissive-layer OLEDs.
A rising current efficiency of 1.31 cd/A and luminance of 1770 cd/m2 were obtained
in the device.