Dinuclear cyclometalated platinum (II) complexes: Synthesis, photophysics, and monomolecular electroluminescence

Article abstract of DOI:10.1016/j.orgel.2012.05.011

Two novel dinuclear platinum (II) complexes of (C₁₂Rppy) ₂Pt₂(dipic) (R = H and F) were synthesized and characterized, where C₁₂Rppy is a 2-phenylpyridine derivative modified with dodecyloxy groups and dipic is

Full text of DOI:10.1016/j.orgel.2012.05.011

Organic Electronics 13 (2012) 1646–1653
Contents lists available at SciVerse ScienceDirect
Organic Electronics
journal homepage: www.elsevier.com/locate/orgel
Dinuclear cyclometalated platinum (II) complexes: Synthesis,
photophysics, and monomolecular electroluminescence
⇑
Yafei Wang, Jian Luo, Yu Liu , Zhiyong Zhang, Hua Tan, Junting Yu, Gangtie Lei, Meixiang Zhu,
Weiguo Zhu
⇑
College of Chemistry, Key Lab of Environment-Friendly Chemistry and Application of the Ministry of Education, Xiangtan University, Xiangtan 411105, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Two novel dinuclear platinum (II) complexes of (C12Rppy)2Pt2(dipic) (R = H and F) were
synthesized and characterized, where C12Rppy is a 2-phenylpyridine derivative modified
with dodecyloxy groups and dipic is a bi-picolinic acid derivative linked by biphenyl unit.
Their physical, surface morphologies and optoelectronic properties, as well as molecular
orbitals calculation were investigated. Intense excimer emission for both dinuclear plati-
num (II) complexes were observed in their neat films rather than in their dichloromethane
solution under photo-excitation. In contrary, these dinuclear platinum (II) complexes
exhibited a stronger monomolecular emission instead of excimer emission in their doped
single-emissive-layer polymer light-emitting devices (PLEDs) under electric field owing to
the effect of two alkyloxy groups in the ligand of 2-phenylpyridine. Better electrolumines-
cent emission with a maximum current efficiency of 1.3 cd/A and a maximum luminance of
1407 cd/cm2 was observed in the (C12Hppy)2Pt2(dipic)-doped devices. To our best knowl-
edge, the performance of (C12Rppy)2Pt2(dipic) (R = H and F) is among the top values for the
solution-processed dinuclear platinum (II) complex-based PLEDs reported so far.
Ó 2012 Elsevier B.V. All rights reserved.
Received 6 February 2012
Received in revised form 19 April 2012
Accepted 14 May 2012
Available online 27 May 2012
Keywords:
Electroluminescence
Dinuclear platinum (II) complex
Polymer light emitting devices
Excimer
1. Introduction
(III) and Pt (II), have been significantly developed and
exhibited wide application in OLEDs/PLEDs [6–18].
Organic/polymer light-emitting devices (OLEDs/PLEDs)
are considered to be the next generation of flat panel dis-
plays because of their advantages, e.g. being flexible, print-
able, micro-buildable, and multiple designable, in
comparison to liquid crystal displays (LCDs) and plasma
display panels (PDP) [1–5]. As a promising class of electro-
luminescent materials used in OLEDs, in recent years,
third-row transition metal complexes are attracted much
interest because both singlet and triplet excitons for these
complexes can be utilized to emit light with a 100% inter-
nal quantum efficiency in theory. Therefore, cyclometalat-
ed complexes containing heavy metal ions, e.g. Os (II), Ir
Among these transition-metal complexes, square-pla-
nar platinum (II) complexes have drawn great attention
in the display fields owing to their versatile spectroscopic
properties [19–25]. Unlike the iridium (III) complexes with
octahedral structure, these square-planar platinum (II)
complexes not only exhibit emission typically from ligand
centered (3LC) and/or metal-to-ligand charge transfer
(3MLCT) states, but also present a tendency to form stack-
ing structures or dimers controlled by PtꢀꢀꢀPt and/or
pꢀꢀꢀp
interactions. Therefore, red-shifted phosphorescent emis-
sion was often observed for the square-planar platinum
(II) complexes owing to the metal–metal-to-ligand charge
transfer (3MMLCT) and/or excimeric excited states [26].
With this mind, a lot of researches were focused on
luminescence of the multinuclear platinum (II) complexes
besides the mononuclear ones [26–32]. For example, Wang
et al. investigated the influence of molecular structures on
⇑
Corresponding authors. Tel.: +86 731 58298280; fax: +86 731
58292251.
E-mail addresses: liuyu03b@126.com (Y. Liu), zhuwg18@126.com
(W. Zhu).
1566-1199/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.orgel.2012.05.011

Y. Wang et al. / Organic Electronics 13 (2012) 1646–1653
1647
emission for the bi- and tri-nuclear organoplatinum com-
plexes containing 2,20-dipyridylamino derivative ligands
[29]. Huo et al. studied electroluminescent properties of
the dinuclear cyclometalated platinum (II) complexes
linked by triphenylaniline group with a maximum external
quantum efficiency of 14.7% [31]. Sun et al. systematically
reported the photophysical properties for the tridentate
C^N^N-coordinated dinuclear platinum (II) complexes
[32]. Recently, we prepared a dinuclear platinum (II) com-
plex with a blend of monomolecular and excimer emis-
sions, which results in a single-molecular white emission
in the PLEDs [33]. However, to our best knowledge, all
these dinuclear cyclometalated platinum (II) complexes
usually exhibit the excimer emission besides monomolec-
ular emission. It is difficult to get monomolecular emission
only for these dinuclear platinum (II) complexes.
(C12Hppy)2Pt2(dipic) as dopant displayed better perfor-
mance with a current efficiency of 1.3 cd/A and a lumi-
nance of 1407 cd/cm2. To our best knowledge, the
performance of (C12Rppy)2Pt2(dipic) (R = H and F) is
among the top values for the solution-processed dinuclear
platinum (II) complex-based PLEDs reported so far.
2. Results and discussion
2.1. Synthesis and characterization
The cyclometalated ligands of HC12Rppy (R = H, or F)
and the ancillary ligand of H2dipic were synthesized
according to the analogous method reported by our previ-
ous work [33,34]. The dinuclear platinum (II) complexes of
(C12Rppy)2Pt2(dipic) were prepared by a chloride cleavage
In the line with our previous report, [33] to further im-
prove the solubility of dinuclear platinum (II) complex and
investigate the relationship between molecular structure
and excimer emission, we designed and synthesized two
dinuclear cyclometalated platinum (II) complexes of
(C12Rppy)2Pt2(dipic) (R = H and F), where C12Rppy is a 2-
phenyl pyridine derivative with two dodecyloxy groups
and dipic is a 4,40-dioxyhexyloxy biphenyl-bridged bi-
picolinic acid derivative. The synthetic route of the dinu-
clear platinum (II) complexes is shown in Scheme 1. Intro-
ducing two oxyalkyloxy groups is expected to improve
solubility and film-forming properties of their molecules,
which should efficiently suppress the excimer emission
for the resulting dinuclear platinum (II) complexes under
electric field. As expected, both dinuclear platinum (II)
complexes exhibited few excimer emission in the PLEDs.
Furthermore, the single-emissive-layer (SEL) PLEDs using
reaction between the dimeric precursor of [Pt(C12Rppy)(l-
Cl)]2 and the ancillary ligand of H2dipic in a ratio of 1:1
(Scheme 1). Both platinum (II) complexes were confirmed
by 1H NMR and 13C NMR spectra, MALDI-TOF mass spec-
trometry and elemental analysis, respectively. The NMR
spectra and mass spectrometry demonstrated that both
dinuclear platinum (II) complexes were successfully ob-
tained by a novel coordination reaction (see Fig. S1 in Sup-
porting information).
2.2. Photophysical properties
The UV-vis absorption and photoluminescence (PL)
spectra of both dinuclear platinum (II) complexes in
dichloromethane (DCM) and in their neat films at 298 K
are shown in Fig. 1, and their pertinent photophysical data
are summarized in Table 1. Similar UV–vis absorption
Scheme 1. Synthesis route of (C12Hppy)2Pt2(dipic) and (C12Fppy)2Pt2(dipic).

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Y. Wang et al. / Organic Electronics 13 (2012) 1646–1653
Fig. 1. Normalized UV–vis absorption spectra and PL spectra of
(C12Hppy)2Pt2(dipic) and (C12Fppy)2Pt2(dipic) in DCM and their neat
films at room temperature.
spectra with three typical absorption bands were observed
in DCM. The intense absorption band at about 257 nm in
the high-energy region can be assigned to the singlet
spin-allowed ligand-centered (1LC)
p–
p⁄ transition of the
C12Rppy ligand. The moderate absorption band at about
340 nm and the weak one at about 405 nm in the low-en-
ergy region are attributed to the spin-allowed and spin-
forbidden metal-to-ligand charge transfer (1MLCT and
3MLCT) transitions, respectively. Compared to the
(C12Hppy)2Pt2(dipic), the (C12Fppy)2Pt2(dipic) exhibited a
minor red-shift UV–vis absorption spectra due to the inter-
action of fluorine atom.
Both dinuclear platinum (II) complexes exhibited a sim-
ilar PL profile in DCM and their neat films. A maximum
monomolecular emission peak at 513 nm with a shoulder
at 542 nm is observed for the (C12Hppy)2Pt2(dipic) in
DCM. This emission peak is assigned to the electronic tran-
sition from the MLCT level to ground state. Compared to
the (C12Hppy)2Pt2(dipic), the (C12Fppy)2Pt2(dipic) presents
a 12 nm red-shifted PL profile. This implies that incorpo-
rating an electron-withdrawing fluorine atom in the phe-
nyl unit of cyclometalated ligand is available to decrease
the energy gap. Using (ppy)Pt(acac) as a standard in DCM
(1 ꢁ 10ꢂ5 M), (C12Hppy)2Pt2(dipic) and (C12Fppy)2Pt2(di-
pic) gave a quantum yield (Uem) of 0.032 and 0.028, respec-
tively. The low quantum yields for both dinuclear platinum
compounds should be related to the long multi-alkyloxy
groups in cyclometalated ligand.
Fig. 2. EL spectra and CIE chromaticity diagrams of the (a)
(C12Hppy)2Pt2(dipic)- and (b) (C12Fppy)2Pt2(dipic)-doped PLEDs at differ-
ent dopant concentrations from 1 wt.% to 8 wt.%.
PL profile compared to the (C12Hppy)2Pt2(dipic). This indi-
cates that both dinuclear platinum (II) complexes gave a
complete excimer emission instead of monomolecular
emission in the neat films under photo-excitation. The
excimer emission has not been suppressed for both dinu-
clear platinum (II) complexes in the neat films under this
situation.
2.3. DFT calculations
Unlike the PL profiles of both dinuclear platinum (II)
complexes in DCM, the ones in their neat films exhibit a
significant red-shift emission peaked at 647 7 nm. The
(C12Fppy)2Pt2(dipic) also displayed a 15 nm red-shifted
In order to investigate the effect of electronic transi-
tions on PL property, the molecular orbital calculations
by density functional theory (DFT:b3lyp/6-31 g⁄⁄:lanl2dz)
Table 1
Photophysical and electrochemical properties of (C12Hppy)2Pt2(dipic) and (C12Fppy)2Pt2(dipic).
UV–vis (nm)a
Emissiona (nm)
Emissionb (nm)
Uem
HOMO eV
LUMO eV
Eg eV
Td oC
c
d
Compounds
(C12Hppy)2Pt2(dipic)
(C12Fppy)2Pt2(dipic)
258,341,405
257,345,408
513,542
525,554
640
655
0.032
0.028
ꢂ5.66
ꢂ5.47
ꢂ2.87
ꢂ2.71
2.79
2.76
281
275
a
b
c
Measured in DCM (10ꢂ5 M) at 298 K.
Measured in the neat film at 298 K.
Measured in DCM at 298 K used (ppy)Pt(acac) as the standard.
Estimated from the low-lying absorption edge data.
d

Y. Wang et al. / Organic Electronics 13 (2012) 1646–1653
1649
were performed for both dinuclear platinum (II) com-
plexes. The calculated orbital densities graphs of the low-
est unoccupied molecular orbitals (LUMOs) and highest
occupied molecular orbitals (HOMOs) are shown in
Fig. S2. Obviously, the electronic clouds are distributed
among the Pt center, pyridine and the picolinic acid for
the LUMOs, but are localized principally on the biphenyl
unit for the HOMOs. The calculated HOMOs and LUMOs
energy levels are ꢂ5.23 and ꢂ2.05 eV for (C12Hppy)2Pt2(di-
pic), ꢂ5.26 and ꢂ2.19 eV for (C12Fppy)2Pt2(dipic), respec-
tively. Notably, the fluorine atom in the phenyl is the
major contributor to the LUMOs of (C12Fppy)2Pt2(dipic).
Therefore, the energy gap of the (C12Fppy)2Pt2(dipic) with
fluorine substituent is calculated to be 3.07 eV, which is
lower than that of (C12Hppy)2Pt2(dipic). Incorporating
fluorine substituent in the ppy can make its dinuclear
platinum (II) complex have a minor red-shifted emission
in theory. This result by the theoretical calculation is con-
sistent with the PL phenomena of both dinuclear platinum
(II) complexes.
2.4. Thermal property
The thermal stability of both dinuclear platinum (II)
complexes were evaluated by thermogravimetric analysis
(TGA) under N2 stream with a scanning rate of 20 °C/min,
and their TGA curves are shown in Fig. S3. The decomposi-
tion temperatures (Td) of 281 and 275 °C are observed for
the (C12Hppy)2Pt2(dipic) and (C12Fppy)2Pt2(dipic), respec-
tively, which correspond to a 5% weight loss (Table 1).
Therefore, both dinuclear platinum (II) complexes possess
high thermal stability, which is valuable for OLEDs.
Fig. 3. Atomic force microscope images for the (C12Fppy)2Pt2(dipic)-doped PVK-PBD films at 10% doping concentration: (a) phase images; (b) surface
morphologies. (The film thickness was ꢃ70 nm).

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Y. Wang et al. / Organic Electronics 13 (2012) 1646–1653
2.5. Electrochemical property
Fig. 3 at the given condition. A roughness with
Ra = 1.603 nm and Ra = 0.307 nm were observed in the
(C12Fppy)2Pt2(dipic)-doped film at 0 and 10 V, respectively.
Obviously, this binuclear platinum (II) complex of
(C12Fppy)2Pt2(dipic) with alkoxy groups has good dispersi-
bility in the PVK-PBD blend under electric-excitation. The
(C12Fppy)2Pt2(dipic)-doped film displayed better phase
images at 10 V instead of 0 V. It is suggested that the excel-
lent dispersibility of (C12Fppy)2Pt2(dipic) in the emissive
layer is available to resulted in a significant decrease in
excimer and aggregate formation [36].
Fig. 4 exhibits the luminance–voltage–current density
(L–V–J) curves of the dinuclear platinum (II) complexes-
doped PVK-PBD devices at the dopant concentrations from
1 wt.% to 8 wt.%. It is obvious that the current density in-
creases with increasing dopant concentrations for these
devices. This implies that the energy transfer processes of
these doped devices are dominated by charge trapping
process [37] On the other hand, an increasing trend of
luminance is also observed with increasing dopant concen-
trations from 1 wt.% to 4 wt.%, but a gradually decreasing
trend of luminance is exhibited with further increasing
dopant concentrations from 4 wt.% to 8 wt.% for these de-
vices. The highest luminances of 1407 and 608 cdmꢂ2 are
achieved in the (C12Hppy)2Pt2(dipic)- and (C12Fppy)2Pt2(-
dipic)-doped devices at 4 wt.% doping level, respectively.
The electrochemical property of the (C12Hppy)2Pt2(di-
pic)- and (C12Fppy)2Pt2(dipic)-based neat films were
examined by cyclic voltammetry, and its corresponding
data are listed in Table 1. Only a reversible oxidation po-
tential (Eox) was observed in both dinuclear platinum (II)
complexes. As the reduction potential (Ered) was not dis-
played, the Ered value had to be estimated by the energy
band gap (Eg) and Eox according to the formula: Ere-
d = Eox ꢂ Eg, in which Eg is generally estimated from the
low-lying absorption edge data. The highest occupied
molecular orbit (HOMO) and lowest unoccupied molecular
orbit (LUMO) energy levels (EHOMO and ELUMO) are calcu-
lated
according
to
an
empirical
formula:
ELUMO = ꢂ(Ered + 4.34) and EHOMO = ꢂ(Eox + 4.34), respec-
tively [35]. Obviously, the (C12Fppy)2Pt2(dipic) exhibits in-
creased EHOMO and ELUMO values compared to the
(C12Hppy)2Pt2(dipic).
2.6. Electroluminescent property
To evaluate the electroluminescent (EL) property of the
dinuclear platinum (II) complexes, a class of the single-
emissive-layer PLEDs with a typical configuration of ITO/
PEDOT:PSS
(50 nm)/platinum
complex + PVK-PBD
(70 nm)/LiF (0.5 nm)/Al (150 nm) was initially fabricated.
The EL spectra of the dinuclear platinum (II) complexes-
doped PVK-PBD devices at the dopant concentrations from
1 wt.% to 8 wt.% are shown in Fig. 2. Intense green emission
is observed for all these devices. A distinct emission peak at
about 548 nm with a shoulder at about 514 nm is dis-
played in the EL spectra of the (C12Hppy)2Pt2(dipic)-doped
devices. However, two typical emission peaks at about 528
and 560 nm are exhibited in the EL spectra of the
(C12Fppy)2Pt2(dipic)-doped devices. In additional, a minor
emission peak at about 425 nm from host matrix is only
observed in the EL spectra of the (C12Hppy)2Pt2(dipic)-
doped devices at the dopant concentrations lower than
4 wt.%. At the same time, with increasing the dopant con-
centrations, the CIE (Commission Internationale de l’ Eclai-
rage) coordinates have minor change (Fig. 2). This means
that the dopant concentrations have minor effect on the
EL spectra. Compared to PL profiles of the dinuclear plati-
num (II) complexes in CH2Cl2 and their neat films, the EL
emission is almost dominated by the single dinuclear plat-
inum (II) complexes in these devices. It is noted that few
excimer emission is observed in all EL spectra. Therefore,
the excimer emissions of two dinuclear platinum (II) com-
plexes are efficiently suppressed in these devices under
electric-excitation. This means that incorporating long
chain alkoxy group into cyclometalated ligand is an avail-
able approach for its dinuclear platinum (II) complexes to
give monomolecular EL emission.
In order to make clear why the (C12Fppy)2Pt2(dipic)-
doped devices exhibit mono molecular EL emission, the
(C12Fppy)2Pt2(dipic) film doped with a blend of PVK and
PBD at 10% doping concentration was made. Its surface
morphologies were recorded by atomic force microscopy
(AFM) at different voltages (0 and 10 V). The different
phase images and surface morphologies are shown in
Fig. 4. The L–V–J curves of the (a) (C12Hppy)2Pt2(dipic)- and (b)
(C12Fppy)2Pt2(dipic)-doped PLEDs at different dopant concentrations
from 1 wt.% to 8 wt.%.

Y. Wang et al. / Organic Electronics 13 (2012) 1646–1653
1651
intense UV–vis absorption and emission in the solution.
The excimer emission was efficiently suppressed in the
dinuclear platinum (II) complexes-doped SEL PLEDs under
electric-excitation, which results from a better dispersibil-
ity of dinuclear platinum complexes in host matrix due to
the alkoxy groups. The monomolecular green EL emission
with a maximum current efficiency of 1.3 cd/A and a max-
imum luminance of 1407 cd/cm2 was obtained in the
(C12Hppy)2Pt2(dipic)-doped devices. This work provides
an efficient way to suppress the excimer emission of dinu-
clear platinum (II) complex in PLEDs by incorporating
long-chain alkoxy group.
4. Experiments
4.1. General methods
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 (TLC). Flash col-
umn chromatography and preparative TLC were carried
out using silica gel from Merck (200–300 mesh). All 1H
NMR spectra were acquired at a Bruker Dex-400NMR
instrument using CDCl3 as a solvent. Mass spectra (MS)
were recorded on a Bruker Autoflex TOF/TOF (MALDI-
TOF) instrument using dithranol as a matrix. The UV
absorption and photoluminescence spectra were measured
on a Varian Cray50 and Perkin-Elmer LS50B luminescence
spectrometer, respectively. Cyclic voltammograms (CV)
were performed on a three electrode electrochemical cell
in a 0.1 M tetra(n-butyl)-ammonium hexafluorophosphate
(TBAPF6) solution in acetonitrile at a scan 100 mV/s under
argon atmosphere at room temperature. A platinum wire
and a KCl saturated Hg/HgO were used as counter elec-
trode and reference electrode, respectively. A microplati-
num (ø = 0.8 mm) was used as work electrode. EL spectra
were recorded with an Insta-Spec IV CCD system (Oriel).
Luminance was measured with a Si photodiode and cali-
brated by using a PR-705 spectrascan spectrophotometer
(Photo Research).
Fig. 5. The LE-J curves of the (a) (C12Hppy)2Pt2(dipic)- and (b)
(C12Fppy)2Pt2(dipic)-doped PLEDs at different dopant concentrations
from 1 wt.% to 8 wt.%.
Here, the (C12Hppy)2Pt2(dipic)-doped devices exhibit high-
er luminance than the (C12Fppy)2Pt2(dipic)-doped devices.
Fig. 5 shows the current efficiency (LE)–current density
(J) characteristics of the dinuclear platinum (II) complexes-
doped PVK-PBD devices at the dopant concentrations from
1 wt.% to 8 wt.%. Significant influence of the dopant con-
centration and current density on the current efficiency
is exhibited in these LE-J curves. The maximum current
efficiency of 1.3 cd Aꢂ1 at 97 mA cmꢂ2 is observed in the
(C12Hppy)2Pt2(dipic)-doped devices at 4 wt.% doping level.
It is higher than that value in the (C12Fppy)2Pt2(dipic)-
doped devices at 2 wt.% doping level. Therefore, the
(C12Hppy)2Pt2(dipic)-doped devices exhibit better device
performance than the (C12Fppy)2Pt2(dipic)-doped devices.
4.2. Devices fabrication
A class of the SEL PLEDs with a typical configuration of
ITO/ PEDOT:PSS (50 nm)/platinum complex+PVK-PBD
(70 nm)/LiF (0.5 nm)/Al (150 nm) was initially fabricated
at different doping concentrations from 1 wt.%, 2 wt.%,
4 wt.% to 8 wt.%. In these devices, ITO is used as the anode,
PEDOT:PSS is used as a hole-injection layer, and LiF/Al is
employed as a cathode. The emitting layer consists of the
dinuclear platinum (II) complex dopants and the PVK-
PBD blending host matrix, in which PBD weight ratio is
30 wt.% in the host.
3. Conclusions
Two
dinuclear
platinum
(II)
complexes
of
4.3. Synthesis of (C12Hppy)2Pt2(dipic)
(C12Rppy)2Pt2(dipic) (R = H and F) with two long-chain
dodecyloxy groups and a dipicolinic acid derivative were
obtained. Both dinuclear platinum (II) complex exhibited
To a mixture of K2PtCl4 (0.2 g, 0.48 mmol) and water
(4 mL) was added a solution of the HC12Hppy ligand

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Y. Wang et al. / Organic Electronics 13 (2012) 1646–1653
(0.6 mg, 1.1 mmol) and 2-ethoxyethanol (12 mL). The mix-
ture was stirred under N2 atmosphere at 80 °C for 20 h.
After cooled to RT, the colored precipitate was formed
and filtered off. This collected precipitate was washed with
water and hexane to gain the dimmer of [(C12Hppy)PtCl]2
as a brown solid. The dimmer can be directly used in the
following process.
for Innovation in Hunan Province (CX2011263), and the
Scientific Research Fund of Xiangtan University (11QDZ18,
2011XZX08).
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/
j.orgel.2012.05.011.
A mixture of [(C12Hppy)PtCl]2 (0.2 g, 0.13 mmol), dipi-
colinic acid derivative of H2dipic (81 mg, 0.13 mmol) and
sodium carbonate (0.14 g, 1.3 mmol) were stirred in 2-eth-
oxyethanol (15 mL) under N2 atmosphere at 100 °C for
20 h. After cooled to RT, the mixture was extracted with
DCM and the combined organic layer was dried over anhy-
drous MgSO4 and filtered. The filtrate was evaporated to
remove the solvent and the residue was passed through a
flash silica gel column using ethyl acetate-THF (1:0ꢃ0:1)
as eluent to gain (C12Hppy)2Pt2(dipic) as a red solid
(0.21 g, 38.4%). 1H NMR (400 MHz, CDCl3, TMS), d(ppm):
9.00 (s, 2H), 8.84 (d, J = 4.9 Hz, 2H), 7.89 (d, J = 7.9 Hz,
2H), 7.70 (d, J = 8.6 Hz, 2H), 7.55 (d, J = 8.0 Hz, 4H), 7.47
(d, J = 8.2 Hz, 6H), 6.95–6.93 (d, J = 8.2 Hz, 4H), 6.90 (s,
2H), 6.72 (d, J = 8.2 Hz, 2H), 4.53 (s, 4H), 4.24 (t,
J = 6.3 Hz, 4H), 4.06–4.00 (m, 8H), 3.52 (t, J = 6.5 Hz, 4H),
2.02 (t, J = 6.4 Hz, 4H), 1.86–1.81 (m, 8H), 1.66–1.27 (m,
84H), 0.89 (t, J = 5.2 Hz, 12H). 13C NMR (100 MHz, CDCl3,
TMS), d(ppm): 170.49, 166.81, 159.75, 158.23, 148.42,
141.81, 138.90, 138.67, 133.37, 132.11, 127.83, 127.62,
125.38, 125.08, 119.15, 117.38, 114.83, 108.75, 71.03,
70.56, 69.18, 68.09, 67.92 32.74, 31.91, 29.69, 29.59,
29.46, 29.33, 28.84, 26.16, 25.93, 25.72, 22.66, 14.06. Anal.
Calcd. for C109H157N4O12Pt2: C 62.18, H 7.52, N 2.66. Found:
C 62.23, H 7.73, N 2.63%. TOF-MS:2113.4.
References
[1] L.X. Xiao, Z.J. Chen, B. Qu, J.X. Luo, S. Kong, Q.H. Gong, J.J. Kido, Adv.
Mater. 23 (2011) 926.
[2] A.C. Grimsdale, K.L. Chan, R.E. Martin, P.G. Jokisz, A.B. Holmes, Chem.
Rev. 109 (2009) 897.
[3] K.T. Kamtekar, A.P. Monkman, M.R. Bryce, Adv. Mater. 22 (2010) 572.
[4] J.L. Segura, Acta Polym. 49 (1998) 319.
[5] (a) H.B. Wu, G.J. Zhou, J.H. Zou, C.L. Ho, W.Y. Wong, W. Yang, J.B.
Peng, Y. Cao, Adv. Mater. 21 (2009) 4181;
(b) J.H. Zou, H. Wu, C.S. Lam, C.D. Wang, J. Zhu, C.M. Zhong, S.J. Hu,
C.L. Ho, G.J. Zhou, H.B. Wu, W.C.H. Choy, J.B. Peng, Y. Cao, W.Y. Wong,
Adv. Mater. 23 (2011) 2976;
(c) G.J. Zhou, Q. Wang, C.L. Ho, W.Y. Wong, D.G. Ma, L.X. Wang,
Chem. Commun. (2009) 3574.
[6] M.A. Baldo, D.F. O’Brien, Y. You, A. Shoustikov, S. Sibley, M.E.
Thomopson, S.R. Förrest, Nature 395 (1998) 151.
[7] Y.L. Tung, S.W. Lee, Y. Chi, L.S. Chen, C.F. Shu, F.I. Wu, A.J. Carty, P.T.
Chou, S.M. Peng, G.H. Lee, Adv. Mater. 17 (2005) 1059.
[8] Y.L. Tung, L.S. Chen, Y. Chi, P.T. Chou, Y.M. Cheng, E.Y. Li, G.H. Lee, C.F.
Shu, F.I. Wu, A.J. Carty, Adv. Funct. Mater. 16 (2006) 1615.
[9] (a) Y. Chi, P.T. Chou, Chem. Soc. Rev. 36 (2007) 1421;
(b) P.T. Chou, Y. Chi, Eur. J. Inorg. Chem. (2006) 3319.
[10] E. Holder, B.M.W. Langeveld, U.S. Schubert, Adv. Mater. 17 (2005)
1109.
[11] L. Flamigni, A. Barbieri, C. Sabatini, B. Ventura, F. Barigelletti, Top.
Curr. Chem. 281 (2007) 143.
[12] M.K. Nazeeruddin, M. Gratzel, Struct. Bonding 123 (2007) 113.
[13] P.L. Burn, S.-C. Lo, I.D.W. Samuel, Adv. Mater. 19 (2007) 1675.
[14] S.W. Lai, C.M. Che, Top. Curr. Chem. 241 (2004) 27.
[15] W.Y. Wong, Z. He, S.K. So, K.L. Tong, Z. Lin, Organometallics 24 (2005)
4079.
[16] (a) S.-Y. Chang, J. Kavitha, S.W. Li, C.S. Hsu, Y. Chi, Y.S. Yeh, P.T. Chou,
G.H. Lee, A.J. Carty, Y.T. Tao, C.H. Chien, Inorg. Chem. 45 (2006) 137;
(b) Z. He, W.Y. Wong, X. Yu, H.S. Kwok, Z. Lin, Inorg. Chem. 45 (2006)
10922.
[17] (a) J.A.G. Williams, A.J. Wilkinson, V.L. Whittle, Dalton Trans. (2008)
2081;
(b) S.Y. Chang, Y.M. Cheng, Y. Chi, Y.C. Lin, C.M. Jiang, G.H. Lee, P.T.
Chou, Dalton Trans. (2008) 6901.
[18] (a) G.J. Zhou, W.Y. Wong, S. Suo, J. Photochem. Photobiol. C 11
(2010) 133–156;
(b) W.Y. Wong, C.L. Ho, Coord. Chem. Rev. 253 (2009) 1709–1758;
(c) W.Y. Wong, C.L. Ho, J. Mater. Chem. 19 (2009) 4457;
(d) G.J. Zhou, W.Y. Wong, X.L. Yang, Chem. Asian J. 6 (2011) 1706.
[19] B.W. D’Andrade, J. Brooks, V. Adamovich, M.E. Thompson, S.R.
Forrest, Adv. Mater. 14 (2002) 1032.
[20] E.L. Williams, K. Haavisto, J. Li, G.E. Jabbour, Adv. Mater. 19 (2007)
197.
[21] X. Yang, Z. Wang, S. Madakuni, J. Li, G.E. Jabbour, Appl. Phys. Lett. 93
(2008) 193305.
4.4. Synthesis of (C12Fppy)2Pt2(dipic)
It was prepared according to the synthetic procedure of
(C12Hppy)2Pt2(dipic). 1H NMR (400 MHz, CDCl3, TMS),
d(ppm): 8.99 (s, 2H), 8.74 (d, J = 5.2 Hz, 2H), 7.92 (d,
J = 8.2 Hz, 2H), 7.71 (d, J = 8.6 Hz, 2H), 7.53–7.45 (m, 8H),
7.26 (d, J = 11.9 Hz, 2H), 6.94 (d, J = 8.3 Hz, 6H), 4.53 (s,
4H), 4.24 (t, J = 6.2 Hz, 4H), 4.15 (t, J = 6.5 Hz, 4H), 4.04 (t,
J = 6.2 Hz, 4H), 3.53 (t, J = 6.5 Hz, 4H), 2.02 (t, J = 6.8 Hz,
4H), 1.88 (t, J = 6.5 Hz, 8H), 1.65–1.30 (m, 84H), 0.91 (t,
J = 5.4 Hz, 12H). 13C NMR (100 MHz, CDCl3, TMS), d(ppm):
165.51, 158.23, 148.45, 142.33, 141.94, 138.77, 134.21,
133.31, 132.69, 127.84, 127,60, 125.03, 118.54, 117.57,
114.82, 113.32, 113.10, 112.25, 111.87, 111.64, 71.17,
70.51, 69.86, 69.10, 67.88, 31.81, 29.68, 29.42, 29.37,
29.23, 28.82, 26.16, 26.01, 25.70, 25.48, 22.63, 14.04. Anal.
Calcd. for C109H155F2N4O12Pt2: C 61.13, H 7.30, N 2.62.
Found: C 61.31, H 7.33, N 2.59%. TOF-MS:2143.7.
[22] R.C. Evans, P. Douglas, C.J. Winscom, Coord. Chem. Rev. 250 (2006)
2093.
[23] T.J. Wadas, S. Chakraborty, R.J. Lachicotte, Q.-M. Wang, R. Eisenberg,
Inorg. Chem. 44 (2005) 2628.
Acknowledgements
[24] S. Chakraborty, T.J. Wadas, H. Hester, C. Flaschenreim, R. Schmehl, R.
Eisenberg, Inorg. Chem. 44 (2005) 6865.
[25] (a) G.J. Zhou, X.Z. Wang, W.Y. Wong, X.M. Yu, H.S. Kwok, Z.Y. Lin, J.
Organomet. Chem. 692 (2007) 3461;
Financial support from the National Natural Science
Foundation of China (50973093, 20872124 and 20772101),
the Specialized Research Fund and the New Teachers Fund
for the Doctoral Program of Higher Education of China
(20094301110004, 200805301013), the Scientific Research
Fund of Hunan Provincial Education Department (10A119,
11CY023, 10B112), the Postgraduate Science Foundation
(b) C.L. Ho, W.Y. Wong, B. Yao, Z.Y. Xie, L.X. Wang, Z.Y. Lin, J.
Organomet. Chem. 694 (2009) 2735;
(c) G.J. Zhou, Q. Wang, X.Z. Wang, C.L. Ho, W.Y. Wong, D.G. Ma, L.X.
Wang, Z.Y. Lin, J. Mater. Chem. 20 (2010) 7472.
´
´
[26] Á. Dlez, J. Forniés, C. Larraz, E. Lalinde, J.A. López, A. Martln, M.T.
Moreno, V. Sicilia, Inorg. Chem. 49 (2010) 3239.

Y. Wang et al. / Organic Electronics 13 (2012) 1646–1653
1653
[27] B. Ma, P.I. Djurovich, M.E. Thompson, Coord. Chem. Rev. 249 (2005)
1501.
[33] Y.F. Wang, X.P. Deng, Y. Liu, M.J. Ni, M. Liu, H. Tan, M.X. Zhu, W.G.
Zhu, Y. Cao, Tetrahedron 67 (2011) 2118.
[28] J.A. GarethWilliams, S. Develay, D.L. Rochester, L. Murphy, Coord.
Chem. Rev. 252 (2008) 2596.
[34] Y.F. Wang, Y. Liu, J. Luo, H.R. Qi, X.S. Li, M.J. Ni, M. Liu, M.X. Zhu, W.G.
Zhu, Y. Cao, Dalton Trans. 40 (2011) 5046.
[29] Q.D. Liu, W.L. Jia, G. Wu, S. Wang, Organometallics 22 (2003) 3781.
[30] Z.Q. Guo, M.C.W. Chan, Chem. Eur. J. 15 (2009) 12585.
[31] D.A.K. Vezzu, J.C. Deaton, J.S. Jones, L. Bartolotti, C.F. Harris, A.P.
Marchetti, M. Kondakova, R.D. Pike, S.Q. Huo, Inorg. Chem. 49 (2010)
5107.
[35] Z.J. Si, J. Li, B. Li, Z.R. Hong, S.Y. Liu, W.L. Li, J. Phys. Chem. C 112
(2008) 3920.
[36] X.H. Yang, Z.X. Wang, S. Madakuni, J. Li, G.E. Jabbour, Adv. Mater. 20
(2008) 2405.
[37] Z.Y. Hu, Y.F. Wang, D.Y. Shi, H. Tang, X.S. Li, L. Wang, W.G. Zhu, Y.
Cao, Dyes Pigm. 86 (2010) 166.
[32] P. Shao, Y.J. Li, J. Yi, T.M. Pritchett, W.F. Sun, Inorg. Chem. 49 (2010)
4507.