Highly Efficient Solid-State Phosphorescence of Platinum Dihalide Complexes with 9-Phenyl-9-arsafluorene Ligands

Article abstract of DOI:10.1021/acs.organomet.5b00944

Platinum dihalide (chloride, bromide, and iodide) complexes with 9-phenyl-9-arsafluorene, which can be safely prepared and are air stable, were synthesized. The dibromide and diiodide complexes showed highly efficient phosphorescence even at 298 K in the solid state, and their quantum yields were up to a value of 0.52. The structures of the complexes were analyzed by X-ray crystallography. Time-dependent density functional calculations support our understanding of the initial electron transition processes. The rigid and bulky structure of the arsafluorene backbone effectively induced solid-state phosphorescence unlike that of a triphenylarsine analogue, which has three unbridged phenyl groups.

Full text of DOI:10.1021/acs.organomet.5b00944

Article
pubs.acs.org/Organometallics
Highly Efficient Solid-State Phosphorescence of Platinum Dihalide
Complexes with 9‑Phenyl-9-arsafluorene Ligands
Hiroaki Imoto,† Susumu Tanaka,† Takuji Kato,† Seiji Watase,‡ Kimihiro Matsukawa,‡ Takashi Yumura,§
and Kensuke Naka*,†
†Faculty of Molecular Chemistry and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology,
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
‡Osaka Municipal Technical Research Institute, 1-6-50 Morinomiya, Joto-ku, Osaka 536-8553, Japan
§Faculty of Materials Science and Engineering, Graduate School of Science and Technology, Kyoto Institute of Technology,
Goshokaido-cho, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
S
* Supporting Information
ABSTRACT: Platinum dihalide (chloride, bromide, and iodide)
complexes with 9-phenyl-9-arsafluorene, which can be safely
prepared and are air stable, were synthesized. The dibromide and
diiodide complexes showed highly efficient phosphorescence even
at 298 K in the solid state, and their quantum yields were up to a
value of 0.52. The structures of the complexes were analyzed by X-
ray crystallography. Time-dependent density functional calcula-
tions support our understanding of the initial electron transition
processes. The rigid and bulky structure of the arsafluorene
backbone effectively induced solid-state phosphorescence unlike
that of a triphenylarsine analogue, which has three unbridged
phenyl groups.
heterofluorenes are preferred due to their coordination affinity
for transition metals. Among them, 9-phosphafluorene has been
the most widely researched,10 especially in the fields of
catalysis11 and optoelectronics.12 However, practical application
of 9-phosphafluorene complexes are limited because of their air
sensitivity, which means that oxidized impurities are often
present.11b
Recently, we reported the synthesis of 9-arsafluorenes via
nonvolatile intermediates.13 This safe and facile synthetic
procedure is superior to conventional methods, which use
volatile and toxic organoarsines.14 The synthetic route for 9-
phenyl-9-arsafluorene (3) is shown in Scheme 1.13 The
nonvolatile cyclic oligoarsine precursor hexaphenylcyclohex-
aarsine (1) was prepared from phenylarsonic acid.15 Iodine was
added to 1, yielding diiodophenylarsine (2). The obtained
INTRODUCTION
■
Platinum complexes have attracted much attention as
phosphorescent materials.1 They have many potential applica-
tions: for example, as photocatalysts,2 sensitizers,3 organic light
emitting diodes (OLED),4 and chemosensors.5 Room-temper-
ature solid-state phosphorescence is a prerequisite for these
applications. Thus, the chemical structures of emissive platinum
complexes have been extensively investigated. For example,
Naota and co-workers employed rigid salicylaldimine ligands
incorporating oligoethylene and oligo(ethylene glycol) capsu-
les, and the quantum yields of the complexes were ∼0.38 in the
solid state at 298 K.6 The ligands were designed to avoid
nonradiative decay via concentration self-quenching and
molecular motion around the luminophore. The ligand
structure must be sophisticated to isolate a molecule and to
restrict molecular motion, resulting in highly efficient solid-state
phosphorescence. However, to fulfill these requirements,
complicated ligand designs must be used.7 Consequently, a
simpler ligand design is desirable to allow easy preparation of
phosphorescent platinum complexes in the solid state.
Scheme 1. Synthesis of 9-Phenyl-9-arsafluorene (3)13
From a structural viewpoint, 9-heterofluorene8,9 is a
promising ligand backbone. It is easy to synthesize, the
biphenylene moiety is highly rigid, and substitution at the 9-
position increases steric hindrance. Nevertheless, there have
been no reports on the solid-state phosphorescence of
transition-metal complexes containing 9-heterofluorene. To
apply 9-heterofluorenes as a ligand, pnictogen-type 9-
Received: November 11, 2015
© XXXX American Chemical Society
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solution of 2 was added to 2,2′-dilithiobiphenyl, and the
product was purified by recrystallization, leading to 3. The
prepared 9-arsafluorenes were more air-stable than phospha-
fluorenes.16 They possessed intense emission in the solid state
at 77 K, though no emission was observed at 298 K.
shown in Figure 1. The complexes adopt a trans square-planar
geometry in the solid state.
In this study, we investigated the synthesis of platinum
dihalide complexes containing 9-phenyl-9-arsafluorene (3-PtX2,
X = Cl, Br, I). We also performed structural analysis of the
synthesized complexes. The dibromide and diiodide complexes
showed highly efficient phosphorescence in the solid state even
at 298 K (the quantum yields were up to a value of 0.52).17
Furthermore, the effect of the rigid fluorene backbone on solid-
state phosphorescence was investigated by comparison with
triphenylarsine (4), whose three phenyl rings can freely rotate.
Crystallographic studies and theoretical calculations support
our understanding of the highly efficient phosphorescence and
electron transitions.
Figure 1. ORTEP drawings of 3-PtX2 (X = Cl, Br, I). Thermal
ellipsoids are drawn at the 50% probability level. Hydrogen atoms and
solvent molecules are omitted for clarity.
RESULTS AND DISCUSSION
■
Synthesis. A schematic of the synthesis of platinum dihalide
complexes with 3 is shown in Scheme 2. A chlorobenzene
Selected bond lengths are given in Table 1. The average Pt−
X bond lengths in 3-PtX2 are 2.3, 2.4, and 2.6 Å, respectively,
Scheme 2. Synthesis of Platinum Dihalide Complexes 3-PtX2
Table 1. Selected Bond Lengths in 3-PtX2
X
Pt−X (Å)
Pt−As (Å)
Cl
Br
I
2.307(2), 2.299(2)
2.4335(8), 2.4229(8)
2.607(1), 2.603(1)
2.394(1), 2.393(1)
2.3954(8), 2.3952(8)
2.398(1), 2.393(1)
reflecting the different radii of the coordinated halogen atoms.
The average Pt−As bond length is approximately 2.4 Å in all
complexes of 3-PtX2. The Pt−As bond lengths are not
influenced by the identity of the halide.
The X−Pt−X (X = Cl, Br, I) angles are 179.5, 179.2, and
179.5°, respectively, and the As−Pt−As angles in 3-PtX2 (X =
Cl, Br, I) are 179.2, 179.0, and 178.6°, respectively (Table 2).
(PhCl) solution of 3 and cis-bis(benzonitrile)dichloroplatinum
(cis-PtCl2(PhCN)2) was refluxed under a nitrogen atmosphere.
Recrystallization from CH2Cl2 and MeOH gave the platinum
dichloride complex 3-PtCl2 as yellow crystals in quantitative
yield. Halogen exchange reactions with KBr and KI were
carried out in a mixture of PhCl and methyl isobutyl ketone
(MIBK) to give 3-PtBr2 (orange crystals) and 3-PtI2 (red
crystals), respectively. The chemical structures of the obtained
complexes were determined by NMR spectroscopy and single-
Table 2. Selected Bond Angles in 3-PtX2
X−Pt−X
As−Pt−As
X
(deg)
(deg)
X−Pt−As (deg)
Cl
179.45(8)
179.16(3)
179.54(3)
179.21(4)
179.00(3)
178.55(4)
93.24(6), 92.86(6), 87.28(6),
86.62(6)
Br
I
93.39(3), 93.09(3), 87.28(3),
86.25(3)
1
crystal X-ray diffraction analysis. In the H NMR spectra, each
93.28(3), 91.93(3), 87.63(3),
87.16(3)
peak due to ligand protons in 3-PtX2 shifted downfield from
that of bare ligand 3. The electron density of the ligands
decreased on coordination to the platinum center, indicating
ligand complexation.
To compare the optical properties of the complexes,
platinum dihalide complexes with triphenylarsine (4-PtX2, X
= Cl, Br, I) were prepared from cis-PtCl2(PhCN)2 by the same
procedure as those of 3. The chemical structures were
confirmed by NMR spectroscopy. The signals in the 1H
NMR spectra of 4-PtX2 shifted downfield after the coordina-
tion.
Crystallographic Studies. Crystallographic studies on 3-
PtX2 were carried out to understand the solid-state structural
features. Crystals for X-ray diffraction analysis were prepared by
slow mixing of MeOH with the CH2Cl2 solutions. The chloride,
bromide, and iodide complexes of 3-PtX2 crystallized in the
Thus, the geometries around the metal in the obtained
complexes were all planar in the solid state. The As−Pt−X
angles are approximately 90°, and the sums of the As−Pt−X
angles are 360°, consistent with square-planar coordination to
the platinum center.
The symmetry of the obtained complexes was collapsed in
the crystalline state. The 9-arsafluorene moieties were slightly
bent in the complexes with Pt, as shown by the interplanar
angles of the five-membered ring and the fused benzene rings.
The average interplanar angles of 3-PtX2 (X = Cl, Br, I) are 2.6,
3.0, and 4.0°, respectively. In addition, the twist of the phenyl
ring to the fluorene moiety was estimated by the torsion angle
given by C−C−As−centroid, as shown in Figure 2. All of the
complexes have different torsion angles: 3-PtCl2 (26.4 and
1.6°), 3-PtBr2 (23.0 and 3.4°), and 3-PtI2 (18.6 and 11.2°). In
the case of 3-PtI2, the difference in the torsion angles was much
triclinic space group P1 for the chloride and bromide and
̅
orthorhombic Pna21 for the iodide. The structures of 3-PtX2
are asymmetrical. ORTEP drawings of the complexes are
B
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shown in Figure 4. In the excitation spectra (Figure 4a), the
absorption maxima were observed at the approximately same
Figure 2. Estimation of the twist of the phenyl ring with respect to the
fluorene moiety in 3-PtX2.
smaller than in those of 3-PtCl2 and 3-PtBr2, suggesting that 3-
PtI2 has a more symmetrical structure.
Optical Properties. UV−vis absorption spectra of 3-PtX2
were measured in chloroform (Figure 3a). The longest
Figure 4. (a) Excitation spectra of 3-PtX2 in the solid state (λem 680
nm). (b) PL spectra of 3-PtX2 (X = Cl, Br, I) in the solid state (λex
403, 370, and 400 nm, respectively). Both excitation and PL
measurements were carried out at 298 K.
wavelength as those of the diffuse reflection spectra in Figure
3b. Thus, it is the HOMO−LUMO transitions, which are
forbidden in solutions but allowed in the solid state, that are
responsible for this emission.
The solid-state emission properties of 3- and 4-PtX2 are
summarized in Table 3. The quantum yields of 3-PtX2 (X = Cl,
Table 3. Solid-State Emission Properties of 3-PtX2 and 4-
PtX2
Figure 3. (a) UV−vis absorption spectra of 3-PtX2 in chloroform
solutions (c = 6.3 × 10−5 M). (b) Diffuse reflection spectra (the
Kubelka−Munk calibration) and photographs of 3-PtX2 in the solid
state.
298 K
77 K
a
b
a
b
ligand
X
λmax (nm)
Φ
λmax (nm)
Φ
3
3
3
4
4
4
Cl
Br
I
624
626
640
n.d.
n.d.
0.01
0.26
0.52
n.d.
603
618
624
581
c
0.53
0.88
0.73
0.82
c
absorption maxima of 3-PtX2 (X = Cl, Br, I) lie in the UV
region (292, 317, and 367 nm, respectively), corresponding
with the results of TD-DFT calculations using the B3LYP
functional as implemented in Gaussian 09 (Table S5 in the
Supporting Information).18 However, the solids of 3-PtX2 (X =
Cl, Br, I) were yellow, orange, and red, respectively (Figure 3b).
In the UV−vis absorption spectra measured under concen-
trated conditions (Figure S8 in the Supporting Information),
no new peaks due to intermolecular interactions, i.e., π−π or
Pt−Pt interactions, were observed. On the other hand, in the
solid state, low-lying absorption bands may be observed
because, on symmetry lowering, the forbidden transitions
become allowed.19 The calculated HOMO−LUMO transition
energies of 3-PtX2 (X = Cl, Br, I) are 470.5, 495.9, and 540.0
nm, respectively. These values correspond to the diffuse
reflection spectra in Figure 3b. Thus, the electron transitions
are responsible for the colors of the solid samples.
Cl
Br
I
n.d.
647
0.03
626
0.67
a
b
c
Emission maxima. Absolute quantum yields. The emission
properties of 4-PtBr2 were not determined because it showed
polymorphism; for further details, see ref 21.
Br, I) are 0.01, 0.26, and 0.52, respectively, and the quantum
yield was higher for heavier halides. This is probably because
the heaver and larger halogen atoms can move less in a
crystalline matrix. In particular, the quantum yield of 3-PtI2 was
significantly high.17 In the crystalline state, 3-PtI2 prevented
π−π interactions, and the H−I interaction effectively fixed the
molecular conformation (Figure 5).20 Furthermore, the
quantum yields of 3- and 4-PtX2 (X = Cl, Br, I) were improved
3-PtX2 showed intense emissions in the solid state at 298 K;
in contrast, no emissions were observed in solution. Exciton
deactivation, caused by molecular motion, was reduced in the
solid state. The crystalline samples recrystallized from CH2Cl2
and MeOH showed bright luminescence. However, the
dispersion samples, measured on the aggregates prepared by
slow mixing of poor solvents (hexane or MeOH) with good
solvents (CH2Cl2), were nonemissive. Thus, 3-PtX2 showed
crystallization-induced emission (CIE) activity.
For the measurement of solid-state emissions, all samples
were prepared by recrystallization from CH2Cl2 and MeOH.
The solid-state excitation and PL spectra of 3-PtX2 at 298 K are
Figure 5. (a) Packing structure of 3-PtI2. Hydrogen atoms are omitted
for clarity. (b) Intermolecular H−I interaction.
C
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by cooling to 77 K, which reduced molecular motion. The
emission lifetimes were measured to examine the components
of their emissions in the solid state at 298 K (Figure S9 in the
Supporting Information). The emissions were composed of
single-lifetime components, and the lifetimes of 3-PtX2 (X = Cl,
Br, I) are 3.2, 12.0, and 25.5 μs, respectively, long enough to
conclude that the emissions are due to phosphorescence.
Notably, 4-PtX2 showed either no or very weak emissions at
298 K (Figure 6), despite the intense emission observed at 77
EXPERIMENTAL SECTION
■
Materials. cis-Bis(benzonitrile)dichloroplatinum (cis-
PtCl2(PhCN)2) were purchased from Sigma-Aldrich Co., Ltd.
Dichloromethane (CH2Cl2), methanol (MeOH), chlorobenzene
(PhCl), methyl isobutyl ketone (MIBK), potassium bromide, and
potassium iodide were purchased from Nacalai Tesque, Inc. Other
chemicals were purchased from Wako Pure Chemical Industry, Ltd.
All commercially available chemicals were used without further
purification. Hexaphenylcyclohexaarsine (1) was prepared following
a literature procedure.15
Measurements. 1H NMR (400 MHz) spectra were recorded on a
Bruker DPX-400 spectrometers, and samples were measured in CDCl3
using Me4Si as an internal standard. The following abbreviations are
used; s, singlet; d, doublet; t, triplet; m, multiplet. The UV−vis spectra
were recorded on a Jasco spectrophotometer (V-670 KKN). Emission
spectra were obtained on an FP-8500 instrument (JASCO), and
absolute PL quantum yields (Φ) were determined using a JASCO
ILFC-847S instrument; the quantum yield of quinine sulfate reference
was 0.52, which is in agreement with the literature value.22 Emission
lifetimes were measured using Quantaurus-Tau (Hamamatsu
Photonics).
X-ray Crystallographic Data for Single-Crystalline Products.
The single crystals were mounted on glass fibers with epoxy resin.
Intensity data were collected at room temperature on a Rigaku RAXIS
RAPID II imaging plate area detector with graphite-monochromated
Mo Kα radiation. The crystal to detector distance was 127.40 mm.
Readout was performed in the 0.100 mm pixel mode. The data were
collected at room temperature to a maximum 2θ value of 55.0°. Data
were processed by the PROCESS-AUTO23 program package. An
empirical or numerical absorption correction24 was applied. The data
were corrected for Lorentz and polarization effects. A correction for
secondary extinction25 was applied. The structures were solved by
Patterson methods26 and expanded using Fourier synthesis.27 Some
non-hydrogen atoms were refined anisotropically, while the rest were
refined isotropically. Hydrogen atoms were refined using the riding
model. The final cycle of full-matrix least-squares refinement on F2 was
based on observed reflections and variable parameters. In the case of
the product recrystallized from acetone, the final cycle of full-matrix
least-squares refinement on F was based on observed reflections and
variable parameters. All calculations were performed using the
CrystalStructure28,29 crystallographic software package. Crystal data
and more information on X-ray data collection are summarized in
Table S1 in the Supporting Information.
Figure 6. Photographs of 3- and 4-PtX2 (X = Cl, Br, I) under UV
irradiation (365 nm) at 298 K.
K.21 The molecular motions of the three phenyl rings in 4 were
less restricted than in the fluorene moiety of 3 at 298 K;
however, the motion of the phenyl rings was frozen at 77 K.
This result suggests that the rigid fluorene backbone was
responsible for the solid-state phosphorescence of 3-PtX2 even
at room temperature.
CONCLUSION
■
In conclusion, we synthesized the platinum dihalide complexes
3-PtX2 (X = Cl, Br, I) using 9-phenyl-9-arsafluorene (3), which
can be prepared by a safe and facile process. These complexes
had CIE activity and showed highly efficient phosphorescence
at 298 K in the solid state. In particular, the quantum yield of 3-
PtI2 (Φ = 0.52) was significantly high. In the case of using
triphenylarsine 4 as a ligand, the iodine complex 4-PtI2 emitted
weakly at 298 K. From the X-ray diffraction results, the
complexes of 3-PtX2 had asymmetrical structures without large
distortions, enabling HOMO−LUMO transitions. Bulky and
rigid 9-phenyl-9-arsafluorene ligands prevented intermolecular
π−π interactions and molecular motion, which would otherwise
deactivate the excitons via a nonradiative pathway. This is the
first study on the use of a 9-heterofluorene backbone to
construct solid-state phosphorescent platinum complexes. As a
general strategy to improve the emission properties, multi-
dentate ligands have been used to enhance the structural
rigidity of the complex, and bulky substituents have been
incorporated to avoid close packing of adjacent molecules.6,7a−g
Furthermore, the design of the ligand is simpler than that for
existing ligands.
Syntheses. 13C NMR was not measured for complexes 3-PtX2 and
4-PtX2 because of the low solubility of the products.
Synthesis of 3-PtCl2. A PhCl solution (10 mL) of 3 (0.160 g, 0.525
mmol) and cis-PtCl2(PhCN)2 (0.124 g, 0.262 mmol) was refluxed
under N2 overnight. The solvent was removed in vacuo and,
subsequently, recrystallized from CH2Cl2 and MeOH, yielding 3-
PtCl2 as a yellow solid (0.218 g, 0.249 mmol, 95%). 1H NMR (CDCl3,
400 MHz): δ 8.21 (d, 1H, J = 7.2 Hz), 7.94 (d, 1H, J = 7.6 Hz), 7.73
(d, 1H, J = 8.4 Hz), 7.60 (d, 1H, J = 7.6 Hz), 7.56 (t, 2H, J = 8.2 Hz),
7.43 (t, 2H, J = 3.2 Hz), 7.33−7.38 (m, 5H) 7.18 (t, 1H, J = 7.4 Hz),
7.10 (t, 1H, J = 7.6 Hz) ppm.
Synthesis of 3-PtBr2. A PhCl (5 mL) and MIBK (1 mL) solution of
3-PtCl2 (23.5 mg, 0.027 mmol) and KBr (88.6 mg, 0.75 mmol) was
refluxed overnight under N2. The solvents were removed in vacuo, and
CH2Cl2 was added to the residue. After filtration, the solvent was
removed in vacuo. The residue was recrystallized from CH2Cl2 and
MeOH to give 3-PtBr2 as an orange solid (15 mg, 0.015 mmol, 57%).
1H NMR (CDCl3, 400 MHz): δ 8.27 (d, 2H, J = 7.6 Hz), 7.94 (d, 2H,
J = 8.0 Hz), 7.54 (t, 2H, J = 6.6 Hz), 7.37 (t, 2H, J = 6.8 Hz), 7.21−
7.34 (m, 5H) ppm.
Synthesis of 3-PtI2. A PhCl (4 mL) and MIBK (0.5 mL) solution of
3-PtCl2 (46.1 mg, 0.053 mmol) and KI (177 mg, 1.07 mmol) was
refluxed overnight under N2. The distilled water (5 mL) was added to
the reaction mixture, leading to a red precipitate in the organic layer.
The precipitates were collected by filtration to give 3-PtI2 as a red solid
Facile synthesis, air stability, and simple structure are great
advantages in the molecular design of ligands for solid-state
emissive complexes. This ligand will open a new route to
luminescent materials. Further functions of these ligands and
complexes with other metals are under investigation.
1
(43 mg, 0.041 mmol, 77%). H NMR (CDCl3, 400 MHz): δ 8.25 (d,
D
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2H, J = 7.6 Hz), 7.93 (d, 2H, J = 8.4 Hz), 7.54 (t, 2H, J = 7.6 Hz), 7.39
(t, 2H, J = 7.0 Hz), 7.24−7.36 (m, 5H) ppm.
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Synthesis of 4-PtCl2. A PhCl solution (7 mL) of 4 (0.162 g, 0.529
mmol) and cis-PtCl2(PhCN)2 (0.125 g, 0.265 mmol) was refluxed
under N2 overnight. The solvent was removed in vacuo, and
subsequent recrystallization from CH2Cl2 and MeOH gave 4-PtCl2
as a pale yellow solid (223 mg, 0.254 mmol, 96%). 1H NMR (CDCl3,
400 MHz): δ 7.72 (dd, 6H, J = 6.8 Hz, 1.2 Hz), 7.45−7.38 (m, 9H)
ppm.
Synthesis of 4-PtBr2. A PhCl (5 mL) and MIBK (1 mL) solution of
4-PtCl2 (23.9 mg, 0.027 mmol) and KBr (88.1 mg, 0.70 mmol) was
refluxed overnight under N2. The solvents were removed in vacuo, and
CH2Cl2 was added to the residue. After filtration, the solvent was
removed in vacuo. The residue was recrystallized from CH2Cl2 and
MeOH to give 4-PtBr2 as a yellow solid (15 mg, 0.015 mmol, 57%).
1H NMR (CDCl3, 400 MHz): δ 7.73 (dd, 6H, J = 6.0 Hz, 1.6 Hz),
7.43−7.40 (m, 9H) ppm.
Synthesis of 4-PtI2. A PhCl (4 mL) and MIBK (0.5 mL) solution of
4-PtCl2 (46.3 mg, 0.053 mmol) and KI (177 mg, 1.07 mmol) was
refluxed overnight under an N2 atmosphere. The solvents were
removed in vacuo, and CH2Cl2 was added to the residue. After
filtration, the solvent was removed in vacuo. The residue was
recrystallized from CH2Cl2 and MeOH to give 4-PtI2 as a yellow solid
1
(42 mg, 0.040 mmol, 75%). H NMR (CDCl3, 400 MHz): δ 7.72−
7.70 (m, 6H), 7.41−7.40 (m, 9H) ppm.
Computational Details. Time-dependentdensity functional
theory (TD-DFT) calculations using the B3LYP functional were
used to investigate the origin of the electronic transitions of the
platinum dihalide (chloride, bromide, and iodide) complexes with 9-
phenyl-9-arsafluorene ligands (3-PtX2). Geometry optimizations were
performed using the crystal structure 3-PtX2 geometries as the initial
coordination. DFT calculations were carried out in Gaussian 09.18 The
CEP-121G basis set was used for the Pt and I atoms, and the 6-311G*
basis set was used for As, Br, C, Cl, and H atoms.
ASSOCIATED CONTENT
■
S
* Supporting Information
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The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.5b00944.
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X-ray data for 3-PtCl2 (CIF)
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X-ray data for 3-PtI2 (CIF)
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AUTHOR INFORMATION
2015, 21, 7441. (i) Fornies, J.; Gimenez, N.; Ibanez, S.; Lalinde, E.;
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Corresponding Author
*K.N.: tel, +81-75-724-7534; e-mail, kenaka@kit.ac.jp.
Author Contributions
The manuscript was written through contributions of all
authors. All authors have given approval to the final version of
the manuscript.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank Prof. M. Shimizu and Mr. R. Shigitani of Kyoto
Institute of Technology for emission lifetime measurements.
This study is a part of a Grant-in-Aid for Scientific Research on
Innovative Areas “New Polymeric Materials Based on Element-
Blocks (No. 2401)” (No. 24102003) of The Ministry of
Education, Culture, Sports, Science and Technology, Japan.
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DOI: 10.1021/acs.organomet.5b00944
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