Highly Luminescent Mono- and Dinuclear Cationic Iridium(III) Complexes Containing Phenanthroline-Based Ancillary Ligand

Article abstract of DOI:10.1002/ejic.201801367

A new family of mononuclear (1–2) and dinuclear (3–5) cationic iridium(III) complexes have been synthesized and fully characterized. These complexes contain 2-(4-(trifluoromethyl)phenyl)pyridine (cf₃ppy, L1) and 1-(4-(trifluoromethyl)phenyl)iso

Full text of DOI:10.1002/ejic.201801367

DOI: 10.1002/ejic.201801367
Full Paper
Luminescent Iridium(III) Complexes
Highly Luminescent Mono- and Dinuclear Cationic Iridium(III)
Complexes Containing Phenanthroline-Based Ancillary Ligand
Xiao-Han Yang,[a] Min Li,[a] Hui Peng,[a] Qian Zhang,[a] Shui-Xing Wu,[a] Wan-Qing Xiao,[a]
Xing-Liang Chen,[a] Zhi-Gang Niu,[b] Guang-Ying Chen,[b] and Gao-Nan Li*[a]
Abstract: A new family of mononuclear (1–2) and dinuclear plexes are green-red emissive with quantum yields of 16.6–
(3–5) cationic iridium(III) complexes have been synthesized and 93.5 % and lifetimes of 1.66–2.89 μs in solution at room temper-
fully characterized. These complexes contain 2-(4-(trifluoro- ature. Density functional theory (DFT) calculations have been
methyl)phenyl)pyridine (cf3ppy, L1) and 1-(4-(trifluoro- carried out to gain insight into the nature of the low-lying tran-
methyl)phenyl)isoquinoline (cf3piq, L2) as cyclometalating li- sitions and also to rationalize the electrochemical and photo-
gands, 1,10-phenanthroline (LX-1) as the ancillary ligand and physical properties. These research results reveal that the π-
1,4-bis(1-phenyl-1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)ben-
conjugation system of C^N ligands and the diiridium system
zene (biphen, LX-2) as the bridging ligand. The crystal structure with conjugated bridging ligand are both benefical for the red-
of LX-2 has been determined by X-ray analysis. All of the com- shift of the absorption and emission spectra.
Introduction
spective advantages. Firstly, the variation of the bridging li-
gands within diiridium complexes can provide another tuning
of photophysical properties in comparison to monoiridium sys-
tems.[17] Secondly, the rigid conjugated bridging ligands in di-
nuclear complexes can facilitate spin-orbit coupling, improve
the radiative rate constant (kr), and hence increase the phos-
phorescence efficiency, as required for use in organic light-
emitting diodes.[18,19] Thirdly, dinuclear complexes easier access
to efficient red emitters through conjugated bridging li-
gands.[20] For example, in 2014, Kozhevnikov and co-workers
described the dinuclear Ir(III) complexes with rigid, bridged bis-
terdentate cyclometallating ligands, which exhibited red emis-
sion with the quantum yield of 0.65.[18] In 2016, Wong and co-
workers reported two red-emitting dinuclear Ir(III) complexes
with short conjugated bridging ligands, and the quantum yield
is up to 0.61.[21] Meanwhile, in a large number of cases, we also
found that the emission bands of dinuclear complexes moved
to longer wavelengths than the related mononuclear com-
plexes,[18,21,22] even reached to the deep-red region.[23,24] This
is because dinuclear complexes with π-extended ligands would
allow a facilitating electron delocalization and thereby lead to
a red-shifted emission.[16,25]
Iridium(III) complexes as phosphorescence emitters have been
extensively employed in full-color organic light-emitting diode
(OLED) displays and white light sources.[1–3] This is due to their
excellent luminescence properties,[4,5] such as high quantum
yields, long excited-state lifetimes, good thermal and photo-
chemical stability, and facile emission color tunability.[6,7] Partic-
ularly, cyclometalated heteroleptic and homoleptic mono-
iridium complexes have been intensely studied over the past
couple of decades.[8–11] In contrast, cyclometalated diiridium
complexes are rarely investigated, because they are usually
more weakly emissive than mononuclear analogues and are,
therefore, generally considered not suitable for OLEDs.[12–14]
However, recent research has found that judicious molecular
design for diiridium complexes can overcome the above defi-
ciency. For example, in 2014, Bryce and co-workers reported
high-efficiency PhOLEDs of dinuclear iridium(III) emitters with
external quantum efficiencies of 11 %.[15] Subsequently, in 2016,
Williams, Kozhevnikov and co-workers reported three very
bright diiridium complexes with solution-state PLQYs of up to
100 %, measured using Ir(ppy)3 in 2-Me THF as the standard.[16]
Accordingly, the study of phosphorescent diiridium com-
plexes is a rapidly expanding topic based on the following pro-
Our group have been committed to exploring new red-emis-
sive Ir(III) complexes with large quantum yields, for the realiza-
tion of highly efficient WOLEDs.[26–28] In general, the red emit-
ters are designed by raising the HOMO level or lowering the
LUMO level of the complex, aiming to reduce the energy
gap.[29] The approach is usually achieved by the introduction of
an electron-donating group into the C^N ligand[30] or extending
π-conjugation of the C^N ligand.[28] Herein, we chose cf3ppy/
cf3piq compounds as the C^N ligands and designed a π-conju-
gated compound (LX-2) as the bridging ligand to yield a series
of dinuclear cyclometalated iridium(III) complexes (3–5). Spe-
[a] Key Laboratory of Electrochemical Energy Storage and Energy Conversion
of Hainan Province,
College of Chemistry and Chemical Engineering, Hainan Normal University,
Haikou 571158, China
E-mail: ligaonan2008@163.com
[b] Key Laboratory of Tropical Medicinal Plant Chemistry of Ministry of Educa-
tion, Hainan Normal University,
Haikou 571158, China
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejic.201801367.
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cially, we designed the different cyclometalated ligands in com- Structural Description
plex 4, which would provide the possibility of dual photolumi-
The crystal structure of LX-2 was determined by X-ray diffrac-
tion, and the ORTEP diagram is shown in Figure 1a. The crystal-
lographic data are given in Table S1; selected bond lengths and
angles are collected in Table S2.
nescence originated from different lowest energy excited states.
For comparative purposes, we also synthesised two correspond-
ing cf3ppy/cf3piq-based mononuclear cyclometalated irid-
ium(III) complexes containing phenanthroline ancillary ligand
(1–2). The electrochemical properties of these complexes have
been measured and analyzed. Their absorption spectra have
been rationalized on the basis of density functional theory
(DFT) and time-dependent DFT (TDDFT). Their luminescence
properties have been investigated both in solution and in the
solid state, where some of them are strongly emissive.
At the end of the molecule, the planar-fused phenanthroline
and the adjacent five-membered ring (C26-N5-C27-C28-N6,
C11-C12-N1-C13-N2) are almost coplanar with the average devi-
ation from a least-squares plane of 0.0183 Å and 0.0211 Å, re-
spectively. In the center of the molecule, the benzene ring (C20-
C21-C22-C23-C24-C25) is slightly twisted with respect to the
two five-membered rings, and the dihedral angles are 34.39°
and 36.25°, respectively. In addition, the other two benzene
rings (C14-C15-C16-C17-C18-C19 and C29-C30-C31-C32-C33-
C34) are largely twisted relative to their connected five-mem-
bered rings with the dihedral angles of 73.48° and 71.85°, re-
spectively. The crystal packing diagram (Figure 1b) shows a
strong face-to-face π-stacking interaction (3.679 Å) between the
pyridine ring and the phenyl ring of different phenanthroline
groups in two neighbouring molecules. These intramolecular
head-to-tail π-π stacking interactions may explain the relatively
poor emission in dinuclear complexes.[21,23]
Results and Discussion
Synthesis and Characterization
Cyclometalated ligands L1-L2, ancillary ligand LX-2 and their
corresponding Ir(III) complexes 1–5 are synthesized and shown
in Scheme 1 and Scheme 2. The ligands L1 and L2 were conve-
niently prepared via an efficient Suzuki coupling reaction with
Pd(dppf)Cl2 catalyst, which used (4-(trifluoromethyl)phenyl)-
boronic acid and the corresponding halogenated hetero-
cyclic compounds 2-bromopyridine/1-chloroisoquinoline. The
ancillary ligand LX-2 was prepared through a multi-component
Electronic Absorption Spectra
cyclization reaction with terephthalaldehyde, aniline and 1,10- The UV-vis absorption of complexes 1–5 in CH2Cl2 solution at
phenanthroline-5,6-dione.[31] Cyclometalated Ir(III) dichloro- room temperature are compared in Figure 2 and the data are
bridged dimers [(C^N)2Ir(μ-Cl)]2 were synthesized by IrCl3·3H2O compiled in Table 1. All five complexes exhibit intense bands in
with cyclometalated ligands (2.2 equiv) in a 2:1 mixture of 2- the UV region (<300 nm), which are assigned to spin-allowed
ethoxyethanol and deionized water according to a similar singlet ligand-centered (1LC) electronic transitions. The weaker
method reported by Nonoyama.[32] Then the new mononuclear bands which extend to 450 nm are ascribed to both metal-to-
and binuclear iridium(III) complexes 1–5 were obtained by the ligand (MLCT) and ligand-to-ligand (LLCT) transitions following
reaction of chloride-bridged dimer [Ir(C^N)2(μ-Cl)]2 with literature precedents.[33,34] Clearly, the absorption spectra of
ancillary ligands in CH2Cl2/MeOH (1:1) followed by addition of mononuclear complexes 1 and 2 are different (Figure 2a), while
excess NH4PF6. All the desired products were characterized by the spectra of the dinuclear complexes 3, 4 and 5 are similar
1H, 19F and 31P NMR spectroscopy, ESI-MS spectrometry and (Figure 2b). For the first series, compared to complex 1, complex
elemental analysis.
2 displays a significant red-shift in the lowest-energy absorption
Scheme 1. Synthetic routes of ligands L1-L2 and LX-2.
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Scheme 2. Synthetic routes of Ir(III) complexes 1–5.
region, resulting from the more extended π-conjugation of the
C^N ligands.[35] For the second series, the trend of the absorp-
tion onset is 3<4<5, similar to that observed for 1–2. This fur-
ther proves the fact that expanding the conjugation system is
favorable for the red shift in spectra.[26,36] To probe the nature
of the low-lying transitions in these complexes, we have per-
formed DFT calculation studies involving the frontier orbital
analyses and the main transitions.
Theoretical Calculations
The most representative molecular frontier orbital diagrams for
these complexes and the energy gap are presented in Figure 3.
The calculated spin-allowed electronic transitions are provided
in Table 2, as well as compared with the experimental absorp-
tion spectra data. The electron density distributions are summa-
rized in Table S3. Especially, the bridge centre in diiridium com-
plexes 3–5 is considered ancillary ligand.
In general, the HOMOs are primarily localized on the iridium
centers and the cyclometalated ligands (Figure 3), corroborat-
ing the later investigated electrochemical behavior. However,
the HOMO-2 of complex 3 is located on the bridging ancillary
ligands. On the other hand, the LUMOs are based largely on
the phenanthroline moieties of bridging ancillary ligands, while
Figure 1. (a) The X-ray molecular structure of LX-2. The H atoms are omitted
for clarity. (b) The π-π packing diagram of LX-2. Selected interactions are
depicted as red dotted line.
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Figure 2. Absorption spectra of (a) 1–2 and (b) 3–5 in CH2Cl2 solution.
Table 1. Photophysical and electrochemistry data of complexes 1–5.
Complex
Absorption λabs [nm][a]
Emission
Electrochemistry
E
solution
solid
em
λ
[nm][a] ΦPL [%][b] τ [μs][a]
kr (105 s–1 [c]
)
knr (105 s–1 [c]
)
λ
[nm][d]
ox (V)[e]
ΔE (V)[f]
em
1
2
3
4
5
228, 231, 251, 265, 341, 368, 408
227, 231, 234, 272, 286, 341, 358, 380, 435 596
236, 250, 285, 339, 409
238, 250, 285, 341, 356, 408, 438
234, 285, 348, 409, 441
519
93.5
37.2
61.7
16.6
27.2
1.66
2.57
2.89
2.01
1.67
5.63
1.45
2.13
0.83
1.63
0.39
2.44
1.33
4.15
4.36
524, 539
615
554
598, 624(sh)
600, 620(sh)
1.60
1.59
0.92, 1.62
0.86, 1.60
0.81, 1.61
–
–
0.70
0.74
0.80
536
541(sh),593
600
[a] Data were collected from degassed CH2Cl2 solutions at room temperature. [b] fac-Ir(ppy)3 as referenced standard (ΦPL = 0.4).[37] [c] Radiative decay rate
(kr), nonradiative decay rate (knr) and pure radiative lifetime (τr) estimated from the measured quantum yields and lifetimes. [d] Recorded in solid state at
room temperature. [e] Oxidation peak potentials for irreversible processes. [f] Peak splitting between Eox1 and Eox2
.
Figure 3. The frontier molecular orbital energy-level diagrams of 1–5 from DFT calculations.
the LUMO+1 of 2 and LUMO+2s of 1, 4, 5 mainly reside on the → LUMO+1, HOMO-2 → LUMO) are ascribed as MLCT, LLCT and
two or four cyclometalated ligands (Figure 3). Therefore, the LC transitions (Table 2), which are consistent with the actual
lowest-energy electronic transitions (HOMO → LUMO+2, HOMO absorption and emission.
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Table 2. Main experimental and calculated optical transitions for 1–5.
Complex
Orbital Excitations
Primary Character
Oscillation
Strength
Calcd
[nm]
Exptl
[nm]
1
2
3
4
5
HOMO → LUMO+2
HOMO → LUMO+1
HOMO-2 → LUMO
HOMO → LUMO+2
HOMO → LUMO+2
MLCT/LLCT
MLCT/LLCT/LC
MLCT/LLCT
MLCT/LLCT/LC
MLCT/LLCT/LC
0.0697
0.0688
0.6760
0.0732
0.0717
394
452
403
454
455
408
435
409
438
441
From Figure 3, it is found that the more conjugation effect singlet-triplet transitions.[38] When Tamm–Dancoff approxima-
of C^N ligands in 2 and 4–5, compared to 1 and 3, can destabil- tion (TDA)[39] is used, the calculation results come much close
ize the HOMOs and stabilize the LUMOs, thereby resulting in to the experimental values (see Table S4).
much lower transition energies and the red-shifting in absorp-
tion and emission. Particularly, in the case of the diiridium com-
plex 5, the energy gap (3.418 eV, HOMO → LUMO+2) is the
smallest one and the absorption wavelength (455 nm) is the
Emission Properties
longest one in the family of complexes. These results are in
good agreement with the photophysical properties discussed
in this study. Moreover, the trend in the experimental absorp-
tion edge (Table 2) correlates well with the variation rule of the
calculated absorption bands, as does the trend in the experi-
mental emission bands below.
To gain the origins of dual emission for complex 4, we em-
ployed the DFT calculations to investigate the lowest triplet ex-
cited states, as well as compared with complexes 1–2. The spin
densities of the triplet states of complexes 1, 2 and 4 are shown
in Figure S1. The corresponding calculated emission energies
are summarized in Table S4. For the triplet state of complex 4,
two distinct minima (T1a and T1b) are found. Moreover, T1a is
localized at the piq-based side, while T1b at the ppy-based side,
similar with the triplet states of 2 and 1, respectively (see Figure
S1). Thus, the experimental values of 541 nm and 593 nm are
attributed to the 3LLCT/3MLppyCT and 3LC/3MLpiqCT emission,
respectively.
Upon photoexcitation, all of the complexes described in this
study are luminescent in degassed CH2Cl2 solution at room
temperature (Figure 4a). The corresponding data are also sum-
marized in Table 1. Complexes 1, 2, 3 and 5 show broad
unstructured emission bands indicative of a predominately
3MLCT state, whereas complex 4 exhibits dual photolumines-
cence[40–42] originating from mixed 3LLCT/3MLppyCT and 3LC/
3MLpiqCT states, as evidenced in above theoretical calculations.
The emission maxima for 1–5 are in the order 519, 596, 536,
593 and 600 nm, respectively. Within the two series, the emis-
sion bands undergo a red shift in the sequence 1<2 and 3<4<5,
mirroring the trend observed in absorption. In addition, a red-
shifting of ca. 17 and 4 nm for the emission maxima is detected
when passing from the mono- to dinuclear iridium complexes,
1→3 and 2→5, respectively, which in agreement with the pre-
vious reports.[22–24] Consequently, the emission energy of diirid-
ium complex 5 with more extended π-conjugation system is
shifted deeper into the expected red region (λem = 600 nm), as
As shown in Table S4, the emission peak of complex 1 and TD-DFT results clearly indicate. For solid state emissions (Fig-
the higher energy emission peak of complex 4 are well repro- ure 4b), there is a similar trend of luminescence bands with
duced by TDDFT. However, the calculation results for the emis- solution state emissions, that is 1<2 and 3<4<5. Interestingly,
sion peak of complex 2 and the lower energy emission peak of however, the emission band of 2 is larger than 5, probably aris-
complex 4 do not agree well with the experimental ones. The ing from relatively more π–π stacking interactions in the solid
disagreement between calculation and experiment can be as- state. It can be seen from Table 1 that obviously, all of these
cribed to the systematic problem of TDDFT method for these complexes have a stronger bathochromic effect and broader
Figure 4. Normalized emission spectra of 1–5 in degassed CH2Cl2 solution (a) and solid state (b) at room temperature.
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emission than those in the solution state, which is quite typical of the conjugated bridging units in the dinuclear iridium com-
of solid emission feature.[43,44]
plexes to the HOMO levels is negligible, which is correlate with
the DFT predictions earlier.
For all the cases, the luminescence quantum yields in solu-
tion at room temperature are estimated to be 16.6–93.5 %. It is
noteworthy that the quantum yields of red emitters (2, 4, 5) are
remarkably lower than those of other color complexes, in line
with the energy-gap law.[45–47] And, not surprisingly, diiridium
complexes 3 and 5 show much lower quantum yield values
relative to monoiridium species 1 and 2, respectively. Subse-
quently, their degassed lifetimes (τ) were measured at room
temperature, ranging from 1.66 to 2.89 μs (Table 1), which indi-
cated that the emissive excited states have triplet characters.[12]
The radiative and nonradiative rate constants can be calculated
through the equations kr = Φ/τ and knr = (1 - Φ)/τ[48] (see
Table 1). It is evident that the brightest emission for complex 1
is mainly attributed to the largest kr value and the smallest knr
value. For red-emitting dinuclear complexes 4–5, the relatively
weak emission is dominated by large nonradiative decay (knr),
caused by energy gap law.
Conclusion
Herein, we report two mononuclear cf3ppy/cf3piq-based irid-
ium(III) complexes (1–2) and three dinuclear cf3ppy/cf3piq-
based iridium(III) complexes (3–5) with the same bridging bi-
phen ligand (LX-2). Their photophysical properties, theoretical
calculations and electrochemical behaviors have been investi-
gated. All Ir(III) complexes are very brightly luminescent with
high emission quantum yields and short phosphorescence life-
times in solution at room temperature. Their phosphorescent
colors can be tuned from green to red through either extending
π-conjugation system or introducing a second iridium ion. The
spectroscopic and redox characterisation of these complexes
are complemented by DFT and TD-DFT calculations, supporting
3
the assignment of MLCT/3LLCT/3LC to the emissive character.
We also present that π-conjugation bridges can allow electronic
interaction between the two metal centers, causing a red-shift
of absorption and emission spectra. Thus, the dinuclearization
strategy is an effective pathway for obtaining highly efficient
red materials.
Electrochemical Properties
Electrochemical studies of complexes 1–5 were performed in
acetonitrile (Figure 5) and their redox potentials are summa-
rized in Table 1. Complexes 1–2 exhibit an irreversible single-
electron-oxidation peak around 1.59–1.60 V, attributed to the
Ir(III)/Ir(IV) redox couple with a contribution from cyclometal-
ated fragments, as already evidenced by DFT calculations (Table
S3). Complexes 3–5 display two irreversible oxidation peaks,
which are assigned to sequential oxidation of each iridium cen-
ter. The relatively large peak splittings (ΔE = 0.70–0.80 V) be-
tween the two oxidation processes indicate a weak electronic
coupling between the two iridium atoms through the long con-
jugated bridging units.[49,19] When the cyclometalated ligands
in the two series of complexes are altered, the trend of the
oxidation potentials is 1 > 2 and 3 > 4 > 5 (Table 1), while the
order of the HOMO energy levels is 1<2 and 3<4<5 (Table 2).
The findings suggest that more extended π-conjugation on the
C^N ligands can enrich the electron densities and improve the
HOMO energy. In addition, the similar changing rule in the oxid-
ation potentials of the two series indicates that the contribution
Experimental Section
General Information and Materials
All reactions were performed under a nitrogen atmosphere, and all
reagents were purchased and used without further purification un-
less otherwise stated. 1H, 19F and 31P spectra were recorded on a
Bruker AM 400 MHz instrument, and chemical shifts were reported
in ppm relative to Me4Si as an internal standard. ESI-MS spectra
were performed on a Bruker esquire HCT-Agilent 1200 spectrome-
ter. Elemental analyses were performed on a Vario EL Cube Analyzer
system at Hainan Normal University. UV-vis spectra were recorded
on a Hitachi U3900/3900H spectrophotometer. Fluorescence spec-
tra were carried out on a Hitachi F-7000 spectrophotometer as de-
aerated CH2Cl2 solutions at room temperature, as well as for the
neat solid powders. Luminescence lifetime curves were measured
on an Edinburgh Instruments FLS920P fluorescence spectrometer
and the data were treated as one-order exponential fitting using
OriginPro 8 software.
Synthetic Procedures
Synthesis of 2-(4-(trifluoromethyl)phenyl)pyridine (cf3ppy, L1) To a so-
lution of 2-bromopyridine (1.13 g, 7.15 mmol), (Trifluoromethyl)-
phenyl)boronic acid (1.50 g, 7.90 mmol), 2 mol/L K2CO3 (2 mL) in
1,4-dioxane (20 mL), was added Pd(dppf)Cl2 (110 mg) as the cata-
lyst, and the mixture was heated at 90 °C for 12 hours under N2.
After the solvent was removed, H2O (50 mL) and ethyl acetate
(50 mL) were added. The organic phase was washed with brine and
dried with Na2SO4. After concentrated, the residue was purified by
flash column chromatography (petroleum ether/ethyl acetate =
50:1) to obtain L1 (1.35 g, yield: 84.6 %) as a white solid. 1H NMR
(400 MHz, CDCl3) δ (ppm) 8.72 (d, J = 4.0 Hz, 1H), 8.11 (d, J = 8.0 Hz,
2H), 7.72–7.82 (m, 4H), 7.26–7.31 (m, 1H). MS (ESI): m/z 223.13 [M +
H]+ (calcd 223.06).
Synthesis of 1-(4-(trifluoromethyl)phenyl)isoquinoline (cf3piq, L2) A
procedure analogous to that described for L1 was used with 1-
Figure 5. Cyclic voltammograms for complexes 1–5 in CH3CN solution con-
taining n-Bu4NClO4 (0.1 M) at a sweep rate of 100 mV/s.
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chloroisoquinoline instead of 2-bromopyridine to afford L2 as a with DCM. The combined organic phase was concentrated and the
white solid. (0.85 g, yield: 81.7 %). 1H NMR (400 MHz, CDCl3) δ (ppm)
8.63 (d, J = 5.7 Hz, 1H), 8.02 (d, J = 8.5 Hz, 1H), 7.92 (d, J = 8.2 Hz,
1H), 7.79–7.84 (m, 4H), 7.70–7.74 (m, 2H), 7.55–7.59 (m, 1H). MS
(ESI): m/z 273.16 [M + H]+ (calcd 273.08).
residue was purified by column chromatography (DCM/MeOH =
50:1) to afford the binuclear Ir(III) complexes 3 and 5.
Complex 3 (43 mg, yield: 29.8 %), yellow solid. 1H NMR (400 MHz,
DMSO) δ (ppm) 9.34 (d, J = 7.2 Hz, 2H), 8.45–8.51 (m, 4H), 8.19–8.24
(m, 8H), 8.03–8.07 (m, 6H), 7.73–7.80 (m, 13H), 7.54–7.64 (m, 7H),
7.55 (d, J = 8.3 Hz, 2H), 7.39–7.45 (m, 4H), 7.17 (t, J = 6.4 Hz, 4H),
6.39–6.43 (m, 4H). 19F NMR (377 MHz, DMSO) δ (ppm) –61.32 (s, 3F,
CF3), –61.33 (s, 3F, CF3), –69.21 (s, 3F, PF6), –71.09 (s, 3F, PF6). 31P
NMR (162 MHz, DMSO) δ (ppm) –144.29 (hept, PF6). MS (ESI): m/z
1940.23 [M – PF6]+ (calcd 1940.37). Elemental anal. calcd. for
C92H54F24Ir2N12P2: C, 49.55; H, 2.44; N, 7.54 %; found C, 49.53; H,
2.46; N, 7.58 %.
Complex 5 (38 mg, yield: 27.4 %), red solid. 1H NMR (400 MHz,
CDCl3) δ (ppm) 9.32–9.35 (m, 2H), 9.00–9.08 (m, 4H), 8.62 (dd, J =
15.0, 8.4 Hz, 4H), 8.12–8.16 (m, 7H), 7.94–8.02 (m, 10H), 7.77–7.84
(m, 14H), 7.62–7.64 (m, 6H), 7.47–7.57 (m, 10H), 6.44 (s, 2H), 6.37 (s,
2H). 19F NMR (377 MHz, DMSO) δ (ppm) –61.76 (s, 3F, CF3), –61.82
(s, 3F, CF3), –69.20 (s, 3F, PF6), –71.09 (s, 3F, PF6). 31P NMR (162 MHz,
DMSO) δ (ppm) –144.29 (hept, PF6). MS (ESI): m/z 2140.33 [M – PF6]+
(calcd 2140.43). Elemental anal. calcd. for C108H62F24Ir2N12P2: C,
53.38; H, 2.57; N, 6.92 %; found C, 53.41; H, 2.56; N, 6.90 %.
Synthesis of 1,4-bis(1-phenyl-1H-imidazo[4,5-f][1,10]phenanthrolin-2-
yl)benzene (biphen, LX-2) 1,10-phenanthroline-5,6-dione (500 mg,
2.38 mmol), aniline (222 mg, 2.38 mmol), terephthalaldehyde
(160 mg, 1.19 mmol) and NH4Ac (2.93 g, 47.58 mmol) were mixed
into acetic acid (25 mL) and heated at 130 °C for 24 hours under
N2. After cooled to room temperature, the mixture was poured to
ice water and used 25 % ammonia solution to adjust the pH to
neutral. The solid was filtered, dried and recrystallized from meth-
anol to afford a brown solid LX-2 (0.76 g, 48.23 %). 1H NMR
(400 MHz, CDCl3) δ (ppm) 9.12–9.16 (m, 2H), 9.07–9.15 (m, 2H), 9.05
(d, J = 2.8 Hz, 2H), 7.75 (dd, J = 8.1, 4.4 Hz, 3H), 7.61–7.71 (m, 6H),
7.48–7.57 (m, 7H), 7.43 (d, J = 7.1 Hz, 2H), 7.30 (dd, J = 8.4, 4.3 Hz,
2H). MS (ESI): m/z 666.18 [M + H]+ (calcd 666.23).
General synthetic procedure for Ir(III) complexes 1–5.
Synthesis of the mononuclear Ir(III) complexes (1, 2)
The cyclometalated Ir(III) dichloro-bridged dimers [(C^N)2Ir(μ-Cl)]2,
were synthesized by IrCl3·3H2O with 2.2 equiv of the ligand L1 or
L2 in a 3:1 mixture of 2-ethoxyethanol and deionized water accord-
ing to a similar method reported by Nonoyama.[32] And then the
mononuclear Ir(III) complexes 1 and 2 were prepared by the reac-
tion of Ir(III) dichloro-bridged dimers with 2.5 equiv of 1,10-phen-
anthroline (LX-1) in DCM and MeOH (v:v = 2:1) and heated at 40 °C
for 5 hours under nitrogen atmosphere. After the reaction was com-
pleted, NH4PF6 (5.0 equiv.) was added and the reaction mixture was
stirred at room temperature for 3 hours. The reaction mixture was
diluted with water and extracted multiple times with DCM. The
combined organic phase was concentrated and the residue was
purified by column chromatography (DCM/MeOH = 100:1) to afford
pure complexes 1 and 2.
Complex 1 (48 mg, yield: 82.5 %), yellow solid. 1H NMR (400 MHz,
DMSO) δ(ppm) 8.93 (dd, J = 8.3, 1.3 Hz, 2H), 8.46 (d, J = 8.1 Hz, 2H),
8.41 (s, 2H), 8.18–8.22 (m, 4H), 8.00–8.08 (m, 4H), 7.60 (d, J = 5.1 Hz,
2H), 7.42 (dd, J = 8.1, 1.2 Hz, 2H), 7.13–7.16 (m, 2H), 6.42 (d, J =
1.2 Hz, 2H). 19F NMR (377 MHz, DMSO) δ (ppm) –61.31 (s, 3F, CF3),
–69.18 (s, 3F, PF6), –71.07 (s, 3F, PF6). 31P NMR (162 MHz, DMSO) δ
(ppm) –144.20 (hept, PF6). MS (ESI): m/z 817.04 [M – PF6]+ (calcd
817.14). Anal. Calcd for C36H22F12IrN4P: C, 44.96; H, 2.31; N, 5.83 %;
found C, 44.93; H, 2.34; N, 5.86 %.
Synthesis of the binuclear Ir(III) complex 4
To a solution of the ancillary ligand LX-2 (2.2 equiv.) in 6 mL of
DCM and MeOH (v:v = 2:1) at 40 °C under nitrogen atmosphere,
was added the Ir(III) dichloro-bridged dimer [(L1)2Ir(μ-Cl)]2 (100 mg)
in three portions. The reaction mixture was stirred at this tempera-
ture for 3 hours. After this time, the Ir(III) dichloro-bridged dimer
[(L2)2Ir(μ-Cl)]2 (1.0 equiv.) was added and stirred for another 5 hours.
After the reaction mixture was cooled to room temperature, NH4PF6
(8.0 equiv.) was added and the mixture was stirred at room temper-
ature for 8 hours. The reaction mixture was diluted with water and
extracted multiple times with DCM. The combined organic phase
was concentrated and the residue was purified by column chroma-
tography (DCM/MeOH = 50:1) to afford the binuclear Ir(III) complex
4.
Complex 4 (36 mg, yield: 27.3 %), red solid. 1H NMR (400 MHz,
DMSO) δ (ppm) 9.34 (d, J = 8.0 Hz, 2H), 9.02–9.05 (m, 2H), 8.62 (dd,
J = 15.0, 8.6 Hz, 2H), 8.47 (dd, J = 14.8, 8.3 Hz, 2H), 8.14–8.24 (m,
8H), 8.01–8.08 (m, 4H), 7.93–7.96 (m, 4H), 7.72–7.80 (m, 13H), 7.60–
7.63 (m, 7H), 7.52–7.57 (m, 5H), 7.39–7.43 (m, 4H), 7.17 (t, J = 6.4 Hz,
2H), 6.37–6.45 (m, 4H). 19F NMR (377 MHz, DMSO) δ (ppm) –61.32
(s, 3F, CF3), –61.33 (s, 3F, CF3), –61.76 (s, 3F, CF3), –61.82 (s, 3F, CF3),
–69.21 (s, 3F, PF6), –71.10 (s, 3F, PF6). 31P NMR (162 MHz, DMSO) δ
(ppm) –144.20 (hept, PF6). MS (ESI): m/z 2040.35 [M – PF6]+ (calcd
2040.40). Elemental anal. calcd. for C100H58F24Ir2N12P2: C, 51.55; H,
2.51; N, 7.21 %; found C, 51.57; H, 2.50; N, 7.20 %.
Complex 2 (52 mg, yield: 81.6 %), red solid. 1H NMR (400 MHz,
DMSO) δ (ppm) 9.02–9.05 (m, 2H), 8.93 (dd, J = 8.3, 1.3 Hz, 2H), 8.61
(d, J = 8.5 Hz, 2H), 8.42 (s, 2H), 8.09–8.17 (m, 4H), 8.04 (dd, J = 8.2,
5.1 Hz, 2H), 7.87–7.91 (m, 4H), 7.60 (d, J = 6.4 Hz, 2H), 7.46–7.50 (m,
4H), 6.42 (s, 2H). 19F NMR (377 MHz, DMSO) δ (ppm) –61.77 (s, 3F,
CF3), –69.20 (s, 3F, PF6), –71.09 (s, 3F, PF6). 31P NMR (162 MHz, DMSO)
δ (ppm) –144.20 (hept, PF6). MS (ESI): m/z 917.08 [M – PF6]+ (calcd
917.17). Anal. Calcd for C44H26F12IrN4P: C, 49.77; H, 2.47; N, 5.28 %;
found C, 49.79; H, 2.43; N, 5.29 %.
X-ray Structure Determination. X-ray diffraction data were col-
lected with an Agilent Technologies Gemini A Ultra diffractometer
equipped with graphite-monochromated Mo-Kα radiation (λ =
0.7107 Å) at room temperature. Data collection and reduction were
processed with CrysAlisPro software.[50] All of the structures were
solved using Superflip[51] and refined using SHELXL-2014[52] within
Olex2.[53] All non-hydrogen atoms were found in alternating differ-
ence Fourier syntheses and least-squares refinement cycles and,
during the final cycles, refined anisotropically. Hydrogen atoms
were placed in calculated positions and refined as riding atoms with
a uniform value of Uiso.
Synthesis of the binuclear Ir(III) complexes (3, 5)
A mixture of the Ir(III) dichloro-bridged dimers [(C^N)2Ir(μ-Cl)]2
(100 mg) and the ancillary ligand LX-2 (1.1 equiv.) was dissolved in
6 mL of DCM and MeOH (v:v = 2:1), and heated at 40 °C for 10
hours under nitrogen atmosphere. After this time, the reaction mix-
ture was cooled to room temperature and NH4PF6 (8.0 equiv.) was
CCDC 1876931 (for LX-2) contains the supplementary crystallo-
added. The mixture was stirred at room temperature for 5 hours. graphic data for this paper. These data can be obtained free of
The mixture was diluted with water and extracted multiple times
charge from The Cambridge Crystallographic Data Centre.
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[18] P.-H. Lanoë, C. M. Tong, R. W. Harrington, M. R. Probert, W. Clegg, J. A. G.
Williams, V. N. Kozhevnikov, Chem. Commun. 2014, 50, 6831–6834.
[19] D. G. Congrave, Y.-T. Hsu, A. S. Batsanov, A. Beeby, M. R. Bryce, Dalton
Trans. 2018, 47, 2086–2098.
[20] G. Li, D. G. Congrave, D. Zhu, Z. Su, M. R. Bryce, Polyhedron 2018, 140,
146–157.
Electrochemical Measurements. Cyclic voltammetry (CV) was per-
formed on a CHI 1210B electrochemical workstation, with a glassy
carbon electrode as the working electrode, a platinum wire as the
counter electrode, an Ag/Ag+ electrode as the reference electrode,
and 0.1 M n-Bu4NClO4 as the supporting electrolyte.
[21] X. Yang, X. Xu, J. S. Dang, G. Zhou, C. L. Ho, W. Y. Wong, Inorg. Chem.
2016, 55, 1720–1727.
[22] F. Lafolet, S. Welter, Z. Popović, L. De Cola, J. Mater. Chem. 2005, 15,
2820–2828.
[23] L. Donato, C. E. McCusker, F. N. Castellano, E. Zysman-Colman, Inorg.
Chem. 2013, 52, 8495–8504.
[24] G. Li, Y. Wu, G. Shan, W. Che, D. Zhu, B. Song, L. Yan, Z. Sua, M. R. Bryce,
Chem. Commun. 2014, 50, 6977–6980.
[25] V. Chandrasekhar, S. M. W. Rahaman, T. Hajra, D. Das, T. Ghatak, S. Rafiq,
P. Sen, J. K. Bera, Chem. Commun. 2011, 47, 10836–10838.
[26] G.-N. Li, Y. Zou, Y.-D. Yang, J. Liang, F. Cui, T. Zheng, H. Xie, Z.-G. Niu, J.
Fluoresc. 2014, 24, 1545–1552.
Computational Details. All calculations were carried out with
Gaussian 09 software package.[54] The density functional theory
(DFT) and time-dependent DFT (TDDFT) were employed with no
symmetry constraints to investigate the optimized geometries and
electron configurations with the Becke three-parameter Lee-Yang-
Parr (B3LYP) hybrid density functional theory.[55–57] Unrestricted DFT
method was used to optimize the triplet state geometries. The
LANL2DZ basis set was used to treat the Ir atom, whereas the
6–31G* basis set was used to treat C, H, N and F atoms. Solvent
effects were considered within the SCRF (self-consistent reaction
field) theory using the polarized continuum model (PCM) approach
to model the interaction with the solvent.[5859]
[27]
G.-N. Li, S.-B. Dou, T. Zheng, X.-Q. Chen, X.-H. Yang, S. Wang, W. Sun, G.-
Y. Chen, Z.-R. Mo, Z.-G. Niu, Organometallics 2018, 37, 78–86.
[28] Z.-G. Niu, L.-P. Yan, L. Wu, G.-Y. Chen, W. Sun, X. Liang, Y.-X. Zheng, G.-N.
Li, J.-L. Zuo, Dyes Pigm. 2018, 162, 863–871.
[29] H. J. Bae, J. Chung, H. Kim, J. Park, K. M. Lee, T.-W. Koh, Y. S. Lee, S. Yoo,
Y. Do, M. H. Lee, Inorg. Chem. 2014, 53, 128–138.
[30] M. Xu, G. Wang, R. Zhou, Z. An, Q. Zhou, W. Li, Inorg. Chim. Acta 2007,
360, 3149–3154.
[31] A. E. Wendlandt, S. S. Stahl, J. Am. Chem. Soc. 2014, 136, 506–512.
[32] M. Nonoyama, Bull. Chem. Soc. Jpn. 1974, 47, 767–768.
[33] P. M. Griffiths, F. Loiseau, F. Puntoriero, S. Serroni, S. Campagna, Chem.
Commun. 2000, 2297–2298.
Acknowledgments
This work was supported by the National Natural Science Foun-
dation of China (21501037), the Natural Science Foundation of
Hainan Province (218QN236), the 2017 Hainan Normal Univer-
sity's Innovation Experiment Program for University Students-
China and Program for Innovative Research Team in University
(IRT-16R19).
[34] L. He, J. Qiao, L. Duan, G. Dong, D. Zhang, L. Wang, Y. Qiu, Adv. Funct.
Mater. 2009, 19, 2950–2960.
Keywords: Iridium · Dinuclear complexes · Conjugated
ligands · Phosphorescence
[35] Z.-G. Niu, H.-B. Han, M. Li, Z. Zhao, G.-Y. Chen, Y.-X. Zheng, G.-N. Li, J.-L.
Zuo, Organometallics 2018, 37, 3154–3164.
[36] J. Dai, K. F. Zhou, M. Li, H. Q. Sun, Y. Q. Chen, S. J. Su, X. M. Pu, Y. Huang,
Z. Y. Lu, Dalton Trans. 2013, 42, 10559–10571.
[37] K. A. King, P. J. Spellane, R. J. Watts, J. Am. Chem. Soc. 1985, 107, 1431–
1432.
[1] Y. S. Li, J. L. Liao, K. T. Lin, W. Y. Hung, S. H. Liu, G. H. Lee, P. T. Chou, Y.
Chi, Inorg. Chem. 2017, 56, 10054−10060.
[2] K. T. Kamtekar, A. P. Monkman, M. R. Bryce, Adv. Mater. 2010, 22, 572–
582.
[3] K. K. W. Lo, M. W. Louie, K. Y. Zhang, Coord. Chem. Rev. 2010, 254, 2603–
2622.
[4] L. Flamigni, A. Barbieri, C. Sabatini, B. Ventura, F. Barigelletti, Top. Curr.
Chem. 2007, 281, 143–203.
[5] E. Baranoff, E. Orselli, L. Allouche, D. DiCenso, R. Scopelliti, M. Gr€atzel,
M. K. Nazeeruddin, Chem. Commun. 2011, 47, 2799–2801.
[6] M. A. Baldo, M. E. Thompson, S. R. Forrest, Nature 2000, 403, 750–753.
[7] E. Matteucci, A. Baschieri, A. Mazzanti, L. Sambri, J. Avila, A. Pertegas,
H. J. Bolink, F. Monti, E. Leoni, N. Armaroli, Inorg. Chem. 2017, 56, 10584–
10595.
[38] R. Bauernschmitt, R. Ahlrichs, Chem. Phys. Lett. 1996, 256, 454–464.
[39] S. Hirata, M. Head-Gordon, Chem. Phys. Lett. 1999, 314, 291–299.
[40] D. Escudero, D. Jacquemin, Dalton Trans. 2015, 44, 8346–8355.
[41] Y. S. Yeh, Y. M. Cheng, P. T. Chou, G. H. Lee, C. H. Yang, Y. Chi, C. F. Shu,
C. H. Wang, ChemPhysChem 2006, 7, 2294–2297.
[42] D. Escudero, W. Thiel, Inorg. Chem. 2014, 53, 11015–11019.
[43] Q. L. Xu, C. C. Wang, T. Y. Li, M. Y. Teng, S. Zhang, Y. M. Jing, X. Yang,
W. N. Li, C. Lin, Y. X. Zheng, J. L. Zuo, X. Z. You, Inorg. Chem. 2013, 52,
4916–4925.
[44] Z.-G. Niu, T. Zheng, Y.-H. Su, P.-J. Wang, X.-Y. Li, F. Cui, J. Liang, G.-N. Li,
New J. Chem. 2015, 39, 6025–6033.
[45] L. F. Gildea, J. A. G. Williams, Iridium and platinum complexes for OLEDs,
in Organic Light–Emitting Diodes: Materials, Devices and Applications, ed.
A. Buckley, Woddhead, Cambridge, 2013.
[8] T.-Y. Li, J. Wu, Z.-G. Wu, Y.-X. Zheng, J.-L. Zuo, Y. Pan, Coord. Chem. Rev.
2018, 374, 55–92.
[46] S. C. Lo, E. B. Namdas, P. L. Burn, I. D. W. Samuel, Macromolecules 2003,
36, 9721–9730.
[47] E. A. Plummer, J. W. Hofstraat, L. De Cola, Dalton Trans. 2003, 2080–2084.
[48] B. P. Straughan, S. S. Walker. Spectroscopy, 2nd ed.; Chapman andHall:
London, 1976, Vol. 3.
[9] A. F. Henwood, E. Zysman-Colman, Chem. Commun. 2017, 53, 807–826.
[10] Y.-J. Cho, S.-Y. Kim, C. M. Choi, N. J. Kim, C. H. Kim, D. W. Cho, H.-J. Son,
C. Pac, S. O. Kang, Inorg. Chem. 2017, 56, 5305–5315.
[11] B. Balónová, D. R. Martir, E. R. Clark, H. J. Shepherd, E. Zysman-Colman,
B. A. Blight, Inorg. Chem. 2018, 57, 8581–8587.
[49] V. Chandrasekhar, T. Hajra, J. K. Bera, S. M. W. Rahaman, N. Satumtira, O.
Elbjeirami, M. A. Omary, Inorg. Chem. 2012, 51, 1319–1329.
[50] CrysAlisPro Version 1.171.36.21. Agilent Technologies Inc. Santa Clara,
CA, USA, 2012.
[51] L. Palatinus, G. J. Chapuis, J. Appl. Crystallogr. 2007, 40, 786–790.
[52] G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
[53] O. V. Dolomanov, L. J. Bourhis, R. J. Gildea, J. A. K. Howard, H. J.
Puschmann, J. Appl. Crystallogr. 2009, 42, 339–341.
[54] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R.
Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Na-
katsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G.
Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hase-
gawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A.
[12] S. Bettington, M. Tavasli, M. R. Bryce, A. S. Batsanov, A. L. Thompson,
H. A. Al-Attar, F. B. Dias, A. P. Monkman, J. Mater. Chem. 2006, 16, 1046–
1052.
[13] X. Li, D. Zhang, W. Li, B. Chu, L. Han, T. Li, Z. Su, J. Zhu, Y. Chen, Z. Hu, P.
Lei, Z. Zhang, Opt. Mater. 2009, 31, 1173–1176.
[14] A. Auffrant, A. Barbieri, F. Barigelletti, J. Lacour, P. Mobian, J.-P. Collin, J.-
P. Sauvage, B. Ventura, Inorg. Chem. 2007, 46, 6911–6919.
[15] Y. Zheng, A. S. Batsanov, M. A. Fox, H. A. Al-Attar, K. Abdullah, V. Jankus,
M. R. Bryce, A. P. Monkman, Angew. Chem. Int. Ed. 2014, 53, 11616–11619;
Angew. Chem. 2014, 126, 11800.
[16] R. E. Daniels, S. Culham, M. Hunter, M. C. Durrant, M. R. Probert, W. Clegg,
J. A. G. Williams, V. N. Kozhevnikov, Dalton Trans. 2016, 45, 6949–6962.
[17] V. W.-W. Yam, K. M.-C. Wong, Chem. Commun. 2011, 47, 11579–11592.
Eur. J. Inorg. Chem. 0000, 0–0
www.eurjic.org
8
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Montgomery Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd, E. Broth-
ers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J. Normand, K. Raghava-
chari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega,
J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J.
Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi,
C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski,
G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö.
Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09,
Revision A.01, Gaussian, Inc., Wallingford CT, 2009.
[55] C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785–789.
[56] B. Miehlich, A. Savin, H. Stoll, H. Preuss, Chem. Phys. Lett. 1989, 157, 200–
206.
[57] A. D. Becke, J. Chem. Phys. 1993, 98, 5648–5652.
[58] M. Cossi, N. Rega, G. Scalmani, V. Barone, J. Comput. Chem. 2003, 24,
669–681.
[59] J. Tomasi, B. Mennucci, R. Cammi, Chem. Rev. 2005, 105, 2999–3093.
Received: November 7, 2018
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Luminescent Iridium(III) Complexes
X.-H. Yang, M. Li, H. Peng, Q. Zhang,
S.-X. Wu, W.-Q. Xiao, X.-L. Chen,
Z.-G. Niu, G.-Y. Chen, G.-N. Li* ..... 1–10
Highly Luminescent Mono- and Di-
nuclear Cationic Iridium(III) Com-
plexes Containing Phenanthroline-
Based Ancillary Ligand
A new family of mononuclear and di- can be tuned from green to red
nuclear cf3ppy/cf3piq-based iridium(III) through either extending π-conjuga-
complexes containing phenanthroline- tion system or introducing a second
based ancillary ligands have been syn- iridium ion.
thesized. Their phosphorescent colors
DOI: 10.1002/ejic.201801367
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