Design and Synthesis of Heteroleptic Cyclometalated Iridium(III) Complexes Containing Quinoline-Type Ligands that Exhibit Dual Phosphorescence

Article abstract of DOI:10.1021/acs.inorgchem.5b02872

The design and synthesis of some cyclometalated iridium(III) complexes containing quinoline-type ligands as ancillary ligands are reported. The emission spectra of Ir(III) complexes containing a quinolinolate (6, 8, 10) moiety exhibit a single emission pe

Full text of DOI:10.1021/acs.inorgchem.5b02872

Article
pubs.acs.org/IC
Design and Synthesis of Heteroleptic Cyclometalated Iridium(III)
Complexes Containing Quinoline-Type Ligands that Exhibit Dual
Phosphorescence
Sarvendra Kumar,† Yosuke Hisamatsu,† Yusuke Tamaki,‡ Osamu Ishitani,‡ and Shin Aoki*,†,§
†Faculty of Pharmaceutical Science and §Imaging Frontier Cancer, Research Institute for Science and Technology, Tokyo University
of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
‡Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1-NE-1 O-okayama,
Meguro-Ku, Tokyo 152-8550, Japan
S
* Supporting Information
ABSTRACT: The design and synthesis of some cyclometalated iridium(III)
complexes containing quinoline-type ligands as ancillary ligands are reported.
The emission spectra of Ir(III) complexes containing a quinolinolate (6, 8,
10) moiety exhibit a single emission peak at ca. 590 nm, resulting in a red
colored emission. However, Ir(III) complexes containing 8-sulfonamidoquino-
line ligands (11, 13−21) exhibit two different emission peaks (dual emission)
at ca. 500 nm and ca. 600 nm upon excitation at 366 nm, resulting in a red-
colored emission for 11 and a pale yellow-colored emission for 14−18 at 298
K. Especially, a white emission was observed for 19 at 298 and 77 K in
dimethyl sulfoxide. The mechanistic studies based on time-dependent density
functional theory calculations and time-resolved emission spectroscopy
suggest that this dual emission originates from two independent emission
states.
from them can be tuned from blue to red by varying the
ligands.2 These attractive photophysical properties of Ir(III)
complex are now being applied to phosphorescent emitters for
organic light-emitting diodes (OLEDs),3 cell staining dyes,4 pH
sensors,5 oxygen sensors,6 molecules that induce and detect cell
death,7 and asymmetric photoredox catalysis.8
INTRODUCTION
■
Since the pioneering work of Forrest,1 the design and synthesis
of cyclometalated Ir(III) complexes such as 1 and 2 (Scheme
1) have received wide attention due to their high emission
efficiency, excellent stability, and fact that the color emitted
It is known that white OLEDs have been developed in all
phosphor-doped devices with the potential for a 100% internal
quantum efficiency.9 In general, white light OLEDs require a
combination of three different color emitters, blue, green and
red, which is achieved by the deposition of multilayers on top
of other components.3b,10 Therefore, the development of metal
complexes that exhibit a white emission (namely, a white
emission from one compound) would be highly desirable in
terms of reducing the fabrication cost and energy consumption
of such materials.
Scheme 1
The emission properties of cyclometalated Ir(III) complexes
can generally be controlled by the cyclometalated ligands and/
or ancillary ligands that are used. Recently, dual-emitting Ir(III)
complexes have been reported to be attractive candidates for
use as phosphorescent bioimaging probes.11 For example, Lo
and co-workers reported on a series of dual-emissive cyclo-
metalated Ir(III) polypyridine complexes (3a−d) that function
as luminescent sensors for various biomolecules (Scheme
Received: December 11, 2015
© XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
2).11c,g In addition, Lippard and co-workers reported on a new
class of dual-emissive cyclometalated Ir(III) complex 4 as a
ratiometric sensor of Cu(II)11d and Zn(II).11e
for radioprotective agents that can be used to reduce acute side
effects of radiation therapy in the treatment of cancer.17g,17h
This background prompted us to synthesize a series of
heteroleptic cyclometalated Ir(III) complexes containing
quinoline-type ligands such as 8-quinolinols, 8-mercaptoquino-
line, and 8-sulfonamidoquinoline as the ancillary ligand. We
report herein on the design and synthesis of the Ir(III)
complexes 5−8 and 10 with 8-quinolinol, 9 with 8-
quinolinethiol, 12 with 8-aminoquinoline, and 11 and 13−21
with 8-sulfonamidoquinoline (Scheme 3), along with their
crystal structures and photophysical properties. Among them,
complexes 14−16 and 18−21 exhibit dual emission peaks at ca.
500 nm and ca. 600 nm at 298 K upon excitation at 366 nm in
solution as well as in the solid state. The emission spectra of 11,
14, and 19 at low temperature (77 K) were also measured in
glassy dimethyl sulfoxide (DMSO). It is noteworthy that
compound 19, which is composed of a cyclometalated 2-(2,4-
difluorophenyl)pyridine (F2ppy) ligand and an 8-sulfonamido-
quinoline ligand, exhibits close to a white emission at both 298
and 77 K. Time-dependent density functional theory (TD-
DFT) calculations were made, and time-resolved emission
spectra were obtained to collect information on the possible
mechanism for these phenomena.
Scheme 2
RESULT AND DISCUSSION
■
Design and Synthesis of Ir(III) Complexes Having
Quinoline Derivatives and Quinoline Sulfonamide. The
Ir(III) complexes having quinolinol ligands (5−8) were
prepared from dichloro-bridged dimeric complex 22 and 8-
quinolinol (23) or the corresponding 8-hydroxyquinoline
derivatives (24−26)18 (Scheme 4). The complexes (9−21)
were synthesized by the treatment of dichloro-bridged 22,19 28,
35, and 36 with the ligands such as 24, 8-quinolinethiol (27), 8-
aminoquinoline (29), and the corresponding sulfonamidoqui-
noline derivatives (30−34).
Fine yellow crystals of 14, 19, and 20 were obtained by slow
diffusion of hexanes to their solutions in CHCl3 at room
temperature. Their X-ray single-crystal structures are presented
in Figure 1, and representative parameters and selected bond
lengths are listed in Tables 1 and 2, respectively.
As shown in Figure 1, the two pyridines on ppy ligands of 14,
19, and 20 have a trans configuration, and bond lengths of Ir−
N (ppy) and Ir−C (ppy) are 2.04−2.05 and 1.99−2.01 Å,
respectively, which are consistent with those of Ir(ppy)2(acac)
(acac: acetylacetonate).20 In addition, the Ir−N (quinoline)
and Ir−N (benzenesulfonamide) distances of 14, 19, and 20
are 2.13 and 2.18−2.19 Å. As shown in Figure 1a, the distance
between the phenyl ring on the sulfonyl amide part and the
centroid of the pyridine ring on the ppy ligand is 3.47 Å, which
indicates face-to-face π−π stacking interactions. However, such
intramolecular interactions are minimal in the cases of 19 and
20 (Figure 1b,c).
Photophysical Properties of Heteroleptic Iridium
Complexes. The UV−vis absoption spectra of 5−10 (10
μM) in DMSO at 298 K are presented in Figure 2. The
absorption at ca. 275 nm is attributed to spin-allowed π−π*
transitions of both the ppy ligands and the quinoline ligands.
The complexes also exhibit a weak absorption in the region of
ca. 350−500 nm, which is due to spin-allowed and spin-
forbidden metal−ligand change transfer (MLCT) transitions
and spin-forbidden π−π* transitions.15,21 All of the compounds
were recrystallized from CHCl3 and hexanes at least twice
before measurements of UV−vis absorption and emission
Meanwhile, quinoline derivatives have been reported to be
versatile ligands for use in preparing luminescent complexes of
aluminum(III) and other metals12 as electroluminophores and
electron-transporting compounds in OLEDs. For example,
electronic π−π* transitions in the quinolinolate ligands of an
AlQ3 complex are responsible for light emission.13 The highest
occupied molecular orbital (HOMO) and lowest unoccupied
molecular orbital (LUMO) of such complexes are located on
the phenoxide moiety and the pyridyl side of the ligand,
respectively,14 and can affect the emission wavelength. To date,
reports on the synthesis and photophysical properties of Ir(III)-
quinolinolate complexes have appeared,15 albeit their phos-
phorescence intensity is low (Φ < 0.01) in solution.
Quinoline derivatives have also attracted considerable
attention in several scientific fields,16 and we have been
involved in the research on the functions of 8-quinolinols as
ligands in Zn2+-selective fluorophores,17a−c potent inhibitors of
dinuclear Zn2+ peptidase such as aminopeptidase from
Aeromonas proteolytica (AAP),17d−f and potential candidates
B
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
on the 5 and 7 positions of the quinoline ring, exhibit a red-
colored emission at ca. 590−600 nm with Φ values of 0.13,
0.11, and 0.21, respectively, as shown in Figure 3. The emission
lifetimes of the Ir(III) complexes 6, 8, and 10 are on a
microsecond time scale, indicating that their emissions are due
to excited triplet states. All of the photophysical data of 5−10
are summarized in Table 3.
Scheme 3
We synthesized Ir(III) complexes 11 and 13−21, containing
8-sulfonamidoquinoline ligands as the ancillary ligands. Their
UV−vis absorption spectra in DMSO (10 μM) are shown in
Figure S1 in Supporting Information. The absorption at ca. 275
nm is attributed to the spin-allowed π−π* transitions of the
phenylpyridyl and quinoline ligands. The complexes also
exhibited a weak absorption in the region of ca. 350−530
nm, which are due to spin-allowed and spin-forbidden metal−
ligand change transfer (MLCT) transitions and spin-forbidden
π−π* transitions. The excitation spectra of 11, 14, and 19 (10
μM), which were measured in degassed DMSO (Figure S2 in
Supporting Information), were almost identical to their UV−vis
absorption spectra. Photophysical data of 11−21 are
summarized in Table 4.
The emission spectra of 11−21 in degassed DMSO
(excitation at 366 nm) were measured at 298 K (Figure 4
and Table 4). Interestingly, it was found that 14−16 that
contain arylsulfonamide groups (10 μM) exhibit dual emissions
at ca. 500 nm (high energy (HE) emission band) and ca. 620
nm (low energy (LE) emission band; total Φ = 2.7 × 10−2 for
14, 3.7 × 10−2 for 15, and 3.0 × 10−2 for 16; Figure 4b).
However, 13, with a methylsulfonamide group, exhibits a broad
emission (450 to 600 nm), but the intensity of the LEB is very
weak as compared to the HEB (Figure 4a). Emission of 17 is
very weak and is not included in Figure 4.
Ir(III) complexes 11 containing 1-(4-methylphenyl)-
isoquinoline (mpiq), 18 containing 2-(4-methoxyphenyl)-
pyridine (mppy), or 19−21 containing 2-(2,4-difluorophenyl)-
pyridine (F2ppy) were also prepared, because fac-Ir(mpiq)3
11b
(4f),5d fac-Ir(mppy)3 (4b),2c and fac-Ir(F2ppy)3
exhibit
emissions at ca. 600 nm, ca. 497 nm, and ca. 475 nm,
respectively. As shown in Figure 4c, the LEB for 18−21 is
observed at ca. 620 nm. The HEB of 18 is observed at 487 and
512 nm, and those of 19−21 are observed as two emissions,
possibly due to their vibrationally structured feature (19: 474,
493 nm, 20: 476, 493 nm, and 21: 478, 494 nm, respectively).
The emission spectrum of 12 having no sulfonamide group
in degassed DMSO exhibits a broad emission band between
450 and 600 nm, suggesting that the presence of sulfonyl group
at 8-amino group of 14−16 and 18−21 is essential for apparent
dual color emission. The HEB of 14 and 19 were compared
with fac- and mer-forms of Ir(ppy)3 1a and Ir(F2ppy)3 1d
(Figure S3 in Supporting Information). The fact that HEB of
14 and 19 are different from emission maxima of 1a and 1d
indicates the contamination of 1a and 1d in the samples is
highly unlikely.
The emission maxima of 14 in CHCl3, CH2Cl2, DMSO, and
toluene are summarized in Figure S4 in Supporting Information
and Table 5, indicating that the peak height ratios between
HEB and LEB are almost identical in different solvents.23
The emission spectra of 11, 14, and 19 in glassy DMSO24 at
77 K exhibit a dual color emission with a hypsochromic shift
due to the rigidochromic effect (Figure 5).25 Note that 19
exhibits a white-color emission, possibly due to a hypsochromic
shift.24
spectra. Note also the exactly the same spectra were observed
after recrystallization.
Emission spectra of 5−10 (10 μM) were measured in
degassed DMSO at 298 K (excitation at 366 nm), and their
quantum yields were determined based on the Φ value of
Ir(mpiq)3 (Φ = 0.26) used as a reference.22 Although Ir(III)
complexes 5,15b 7, and 9 exhibited very weak emissions at room
temperature, 6, 8, and 10, which contain sulfonylamide groups
C
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 4
In the emission spectra of 13−17 at 298 K in the solid state,
dual emission peaks (Figure S6 in Supporting Information)
were observed, and the LE bands have a strong emission
intensity compared to that in solutions. It should be added that
17 exhibits two peaks at 521 and 625 nm in the solid state,
while its emission is very weak in solution.
In addition, the emission spectra of 11, 14, and 19 in 5 wt %
doped in a poly(methyl methacrylate) (PMMA) polymer film
(5 wt %) were measured at ambient temperature (samples of
the PMMA film were prepared by using solutions of Ir(III)
complexes and maintaining the films at 40 °C for 24 h). In the
PMMA film, 11, 14, and 19 exhibited dual emission peaks with
different peak ratios compared to those in solution (Figure S7
in Supporting Information), possibly due to the suppression of
nonradiative pathways in the polymer.
Bunz and co-workers reported on the conversion of pictures
colors to digital data.26 In this work, we attempted a rather easy
and convenient method. Namely, emission pictures of 11, 14,
19, and 20 in degassed DMSO solutions were taken by several
digital cameras. Then, we selected the appropriate cameras that
exhibit similar colors as those recognized by our naked eyes and
analyzed these pictures by using the Adobe Photoshop software
without correction. In these measurements, we used at least 10
different points (10 different pixels) in the same picture and
D
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 1. Perspective views of single crystal structures of (a) 14, (b) 19, and (c) 20 with 50% probability ellipsoids.
a
Table 1. Representative Crystallographic Parameters of 14, 19, and 20
14
19
20
empirical formula
Mr
C37H27IrN4O2S·CHCl3
903.27
C37H23F4IrN4O2S·CHCl3
975.22
C38H25F4IrN4O3S
885.88
crystal system
space group
a (Å)
monoclinic
P21/n
triclinic
triclinic
P1
̅
P1
̅
19.194(5)
9.114(5)
19.709(2)
90
11.477(5)
13.075(5)
13.777(5)
73.813(5)
71.921(5)
66.201(5)
1770.0(12)
2
10.355(5)
11.129(5)
16.199(5)
85.020(5)
77.980(5)
84.218(5)
1812.4(13)
2
b (Å)
c (Å)
α (deg)
β (deg)
γ (deg)
V (Å3)
101.926(5)
90
3374(2)
4
Z
ρ
(g·cm−3
)
1.778
1.830
1.623
calc
R
0.028
0.0435
0.0336
Rw
0.0656
0.1096
0.0826
reflection measured/independent
observed ref [I > 2σ(I)]
GOF
17 488/6166
5349
10 243/7103
6326
9253/6502
5874
0.996
1.038
1.042
a
The structures were solved by direct methods (Bruker APEX CCD) and refined by using least-squares techniques (SHELXL-97).
calculated average values to obtain RGB values of each sample.
These RGB values were converted into xy color coordinates to
be plotted in a chromaticity diagram (CIE 1931) as shown in
Figure 6, by using the “Data-E calculator of the ColorMine
library” (Table S1 in Supporting Information).27 As displayed
in Figure 6, 19 and 20 exhibit xy color coordinates (0.31, 0.32)
E
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Table 2. Selected Bond Lengths (Å) of 14, 19, and 20
14
19
20
Ir−Npy
Ir−Cph
Ir−Nquinoline
Ir−Nsulfonamide
2.04, 2.05
2.00, 2.01
2.13
2.04, 2.04
1.99, 2.00
2.13
2.04, 2.05
1.99, 2.00
2.13
2.19
2.18
2.18
Figure 3. Normalized emission spectra of Ir(tpy)3 (dashed curve), 6
(plain curve), 8 (bold curve), and 10 (short dotted curve) (10 μM) in
degassed DMSO at 298 K ([Ir complex] = 10 μM and excitation at
366 nm). (inset) Picture of 6 (10 μM) taken under UV light (365
nm).
a
Table 3. Photophysical Properties of 5−10 (10μM) in
Degassed DMSO at 298 K
UV−visible
b
absorption maxima
(nm)
emission
quantum
lifetime
compound
maxima (nm) yield (Φ)
τ (μs)
c
Ir(tpy)3
300, 367, 453
351, 406, 456
347, 400, 454
289, 350, 404, 464
352, 400, 456
346, 399, 490
345, 398, 489
516
587
588
600
0.50
0.13
0.11
0.21
5
6
2.5
5.7
2.0
7
8
9
10
a
Excitation at 366 nm. Quantum yields were determined using
Ir(mpiq)3 as a reference (Φ = 0.26).22 A 475 nm long wave pass filter
was used. The quantum yield of Ir(tpy)3 was determined using
b
c
quinine sulfate in 0.1 M H2SO4 (ϕ = 0.55).
in DMSO at 298 K, which also produces a white-like colored
emission.
Mechanistic Studies of Dual Emissions. To study the
mechanism for the dual emission from the aforementioned
Ir(III) complexes, TD-DFT calculations were performed for 6,
8, 10−16, and 18−21 by using the Gaussian09 program.28 The
results are summarized in Figure 7 and Table 6 with the main
transition characters. The HOMOs and LUMOs of 6, 11, 12,
14, and 19 are shown in Figure 7. In the case of 6, the TD-DFT
calculation results indicate that the emission peak at ca. 587 nm
3
3
originates from MLquinCT + LquinC transitions.
The major contribution of the triplet transition of 11,
exhibiting a single emission at 602 nm, is possibly due to
HOMO−1 → LUMO (3MLmpiqCT). Interestingly, the HOMO
of 12, which is the parent compound of 14, is localized on the
phenyl ring of ppy, and the LUMO is localized on quinoline,
exhibiting a single emission at 557 nm with a low quantum
yield (Φ = 1.5 × 10−2).
The experimental results of emission of 14 at 496 nm and at
617 nm (Figure 4b and Table 4) are in good agreement with
theoretical values calculated by using TD-DFT (emissions at
493 and 652 nm) as listed in Table 6. Namely, the HOMO of
14 is mainly localized on the Ir center, quinoline ring (quin),
and nitrogen atom (n) of the sulfonamide group of quinoline,
Figure 2. UV−vis spectra of Ir(III) complexes (a) 5 (plain curve), 6
(dotted curve), (b) 7 (plain curve), 8 (dotted curve), (c) 9 (plain
curve), and 10 (dotted curve) in DMSO at 298 K ([Ir complex] = 10
μM).
corresponding to a white emission at 77 K, which are similar to
those of white OLED (WOLED). For reference, a 2:5 mixture
of 372c and 2 has xy color coordinates at x = 0.31 and y = 0.33
F
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Table 4. Photophysical Properties of 11−21 (10 μM) in Degassed DMSO at 298 K (excitation at 366 nm)
emission peaks (nm)
lifetime τ (μs)
a
a
b
c
d
compounds
UV−vis absorption maxima (nm)
HEB
LEB
quantum yield (Φ) HEB LEB (total)
HEB
LEB
11
12
13
14
15
16
17
18
19
20
21
294, 342, 445
347, 394, 424
343, 394, 444
343, 393, 443
341, 391, 441
340, 394, 439
346, 396, 446
305, 374, 427
331, 366, 417
332, 370, 424
330, 367, 423
602
0.35
3.25
557
1.5 × 10−2
0.12
500
496
496
500
623
617
611
622
1.63
4.26
5.14
2.98
1.6 × 10−2 1.1 × 10−2 (2.7 × 10−2
3.2 × 10−2 5.3 × 10−3 (3.7 × 10−2
2.3 × 10−2 7.4 × 10−3 (3.0 × 10−2
)
)
)
8.95
9.65
7.88
487, 512
474, 493
476, 493
478, 494
617
613
617
615
3.6 × 10−2 1.8 × 10−2 (5.4 × 10−2
8.3 × 10−2 1.5 × 10−2 (9.8 × 10−2
4.5 × 10−2 7.0 × 10−3 (5.2 × 10−2
4.8 × 10−2 1.0 × 10−2 (5.8 × 10−2
)
)
)
)
4.43
2.10
2.12
2.23
6.76
10.99
10.01
6.17
a
b
HEB = higher energy emission band, and LEB = lower energy emission band. Quantum yields for HEB and LEB were calculated and listed as well
c
d
as total Φ values. A 435 nm long wave pass filter was used. A 550 nm long wave pass filter was used.
and its LUMO is localized on the quinoline ring, whereas
LUMO+1 and LUMO+2 are mainly localized on the
phenylpyridine (ppy) ligands (Figure 7). This suggests that
the lowest-energy triplet excited state T1 (1.90 eV),
corresponding to an emission at 617 nm, is a mixture of
the same wavelengths (Table 7). The prompt decay of LEB
(1.3 μs) possibly corresponds to tailing of HEB.
Similar results were obtained from the emission decay curves
of 19, which provide a single-component emission lifetime of
1.9 μs at 474 and 493 nm, respectively, and biexponential
emission lifetimes of 1.8 and 17 μs at 613 nm (Figure 8 and
Table 7). The time-resolved emission spectra indicate that both
HEB and LEB have lifetimes of ca. 1−2 μs and that LEB
becomes dominant with a delay time of up to ca. 6 μs. In both
time-resolved emission spectra, observed rise components are
negligible, and the emission maxima and lifetimes of HEB of 14
(τ = 1.7 μs) and 19 (τ = 1.9 μs) are nearly identical to those of
Ir(ppy)2(acac) (τ = 1.6 μs)20 and Ir(F2ppy)2(acac) (τ = 1.0
μs).30 These results suggest that interligand energy transfer
between T1 and T2 is unlikely and that the dual emission of 14
and 19 originates from the two independent emission states, T1
and T2,11,31 although we do not completely exclude the
possibility of very slow energy transfer from T2 to T1.
3
3MLquinCT (d(π) (Ir) → π*(quin)), LquinC (π(quin) →
π*(quin)) and 3ILquinCT (n(sulfonamide) → π*(quin))
transitions. The second lowest-energy state T2 (2.51 eV) of
14, corresponding to an emission at 496 nm, is composed of
3
3MLppyCT (d(π) (Ir) → π*(ppy)) and LquinLppyCT (π(quin)
→ π*(ppy)).
Similarly, lowest-energy triplet excited state T1 (2.08 eV) for
3
3
19 is a mixture of MLquinCT (d(π) (Ir) → π*(quin)), Lquin
C
(π(quin) → π*(quin)) and 3ILquinCT (n(sulfonamide) →
π*(quin)) transitions (613 nm) by calculation, and its second
lowest-energy state T2 (2.76 eV) is composed of MLF2ppyCT
3
3
(d(π) (Ir) → π*(F2ppy)) and LquinLppyCT (π(quin) →
π*(F2ppy)) (476 nm by calculation). Then we conclude that
these two main transition states, T1 and T2, contribute to the
dual emission of Ir(III) complexes 14−21 (Scheme 5).
You et al. reported on tuning of the emission color of
heteroleptic Ir(III) complexes consisting of F2ppy ligands and a
variety of ancillary ligands.29 They concluded that the
interligand energy transfer between the cyclometalated F2ppy
ligand and the corresponding ancillary ligand is the most
probable mechanism, as supported by time-resolved emission
spectroscopy and the observation that the rise component in
time-resolved emission spectrum is strong evidence of an
interligand energy transfer.29b
Therefore, we hypothesize that the interligand energy
transfer (T1 ⇌ T2 in Scheme 5) from HEB to LEB can be
attributed to dual emissions in our Ir(III) complexes, which
prompted us to measure the emission decay of 14 and 19
(excitation at 371 nm) at both HEB and LEB by using time-
resolved emission spectroscopy (Figure S8 in Supporting
Information and Figure 8). The emission decay of 14 at 496
nm provided a single-component emission lifetime of 1.7 μs,
and biexponential emission decay is observed at 617 nm (τ =
1.3 and 12 μs; Figure S8a in Supporting Information and Table
7; for comparison, the emission decay of 11 is shown in Figure
S8b in Supporting Information). The biexponential emission
decay at 617 nm (LEB) is deconvoluted into a prompt decay
component (τ = 1.3 μs), whose contribution is 4% at 617 nm
and a slower decay (τ = 12 μs), whose contribution is 96% at
CONCLUSION
■
In conclusion, we report herein on the synthesis and
photophysical properties of heteroleptic cyclometalated
iridium(III) complexes having the variety of quinoline
derivatives as ancillary ligands. The findings indicate that 14−
16 and 18−21 containing 8-sulfonamidoquinolines exhibit a
dual color emission at ca. 500 nm and ca. 600 nm upon
excitation at 366 nm at 298 K, and especially, 19 exhibits a
white-color emission at 298 K and at 77 K, as displayed in
chromaticity diagram (Figure 6) prepared by using digital
camera and convenient data conversion. The presence of
sulfonyl group on 8-aminoquinoline unit is essential for dual
color emission. The results of theoretical (TD-DFT)
calculations and time-resolved emission spectroscopy suggest
that dual emission of these complexes originates from two
independent emission states. This information provides useful
information for the design and synthesis of new metal
complexes and their applications to OLEDs and related
materials.
EXPERIMENTAL SECTION
■
General Information. IrCl3·3H2O was purchased from Kanto
1
Chemical Co. H NMR spectra (300 MHz) was recorded on a JEOL
Always 300 spectrometer. Electrospray ionization (ESI) mass spectra
(MS) were recorded on a Varian 910-MS. Thin-layer (TLC) and silica
gel column chromatographies were performed using Merck 5554
G
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Table 5. Emission Peaks of 14 (10 μM) in Various Solvents
at 298 K, and 11, 14, and 19 at 77 K
emission maxima (nm)
temperature
(K)
a
a
complex
solvent
HEB
496
LEB
14
14
14
14
14
11
19
DMSO
CHCl3
CH2Cl2
toluene
DMSO
DMSO
DMSO
617
613
611
623
581
597
567
298
298
298
298
77
491
491
496
483, 516
77
457, 489
77
a
Excitation at 366 nm. HEB = higher energy emission band, and LEB
= lower energy emission band.
Figure 5. Emission spectra of 11 (short dotted curve), 14 (bold
curve), and 19 (dashed curve) in glassy DMSO at 77 K. (inset)
Emission pictures of 11, 14, and 19 in glassy DMSO ([Ir complex] =
10 μM and excitation at 366 nm).
ethoxyethanol and water under Ar, to which 2-phenylpyridine had
been added. The resulting reaction mixture was stirred at 110 °C for
24 h to afford a dark brown reaction mixture containing a yellow
precipitate. The precipitate was isolated on a filter, washed with water,
ethanol, and acetone, and dried under vacuo. The NMR spectrum of
the material was found to be identical with that reported in the
literature.19a
Di-μ-chloro-tetrakis[k2(C2,N)-2-mppy]diiridium(III) 3519b and di-
μ-chloro-tetrakis[k2(C2,N)-2-dfppy]diiridium(III) 3619c were synthe-
sized in a similar manner and were used for preparing 22.
Synthesis of Quinoline Derivatives. Compounds (24−26) were
synthesized as described in our previous paper.17g,18 The 8-
sulfonamidoquinoline ligands (29−34) were synthesized by reacting
8-aminoquinoline with the corresponding sulfonyl chlorides in
pyridine at 130 °C under microwave conditions.32 Reaction mixtures
were then poured into water, and the resulting solid was isolated on a
filter and washed with water. When no precipitate was formed, the
product was obtained by extracting the aqueous phase twice with
CH2Cl2. The organic layer was then dried over anhydrous sodium
sulfate and evaporated in vacuo to obtain a solid.
N-(Quinolin-8-yl)methylsulfonamine (30). Yield = 51% (40 mg).
Brown color solid. mp 132 °C. IR (ATR): ν = 3287, 1504, 1472, 1305,
1146, 1087, 970, 829, 760, 545, 508 cm−1. 1H NMR (300 MHz,
CDCl3) δ 8.93 (s, 1H), 8.83 (d, J = 4.2 Hz, 1H), 8.20 (d, J = 8.3 Hz,
1H), 7.87 (d, J = 6.9 Hz, 1H), 7.54 (ddd, J = 12.5, 8.9, 5.4 Hz, 3H),
3.04 (s, 3H) ppm. EI-MS (m/z): Calcd for C10H10N2O2S (M+):
222.0453. Found: 222.0467.
Figure 4. Normalized emission spectra of (a) 11 (plain curve), 12
(dashed curve), and 13 (dotted curve), (b) 14 (bold curve), 15 (plain
curve), and 16 (short dotted curve), and (c) 18 (bold curve), 19
(plain curve), 20 (dashed curve), and 21 (short dotted curve) in
degassed DMSO at 298 K ([Ir complex] = 10 μM and excitation at
366 nm). (inset) Pictures of 11, 14, and 19 (10 μM) taken under UV
light (365 nm).
(silica gel) TLC plates and Fuji Silysia Chemical FL-100D,
respectively. Emission lifetimes were determined using a TSP-1000
(Unisoku Co, Ltd). Density functional theory (DFT) calculations28
were also carried out using the Gaussian09 program (B3LYP, the
LanL2DZ basis set for a Ir atom and the 6-31G basis set for H, C, S,
Br, O, N atoms). The commercial available DMSO (spectrophoto-
metric grade, Wako Chemical Co) was used for the measurement of
photophysical data. Negligible hazard exists in all synthetic procedures.
Synthesis of Di-μ-chloro-tetrakis[k2(C2,N)-2-phenylpyridine]-
diiridium(III) (22). IrCl3·3H2O was suspended in a mixture of 2-
H
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
chromatography with CHCl3 as an eluent and recrystallized from
hexanes/CHCl3 or hexanes/CH2Cl2. Similar procedure was used for
the synthesis of Ir(III) complexes from dichloro-bridged Ir(III)
complexes 28, 35, and 36 and quinoline derivatives.
5: Yield = 66% (16 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 3370, 1603, 1567, 1457, 1384, 1324, 1221, 1157, 1058,
1
1028, 819, 728, 616, 508 cm−1. H NMR (300 MHz, CDCl3) δ 8.81
(d, J = 4.7 Hz, 1H), 7.99 (d, J = 8.4 Hz, 1H), 7.87 (d, J = 7.9 Hz, 1H),
7.80 (d, J = 7.8 Hz, 1H), 7.67 (d, J = 6.2 Hz, 2H), 7.60 (d, J = 7.8 Hz,
4H), 7.54 (d, J = 5.8 Hz, 1H), 7.42 (t, J = 8.0 Hz, 1H), 7.10 (dd, J =
8.4, 4.8 Hz, 1H), 7.03 (m, 2H), 6.96−6.85 (m, 2H), 6.84−6.72 (m,
3H), 6.45 (d, J = 7.9 Hz, 1H), 6.30 (d, J = 6.9 Hz, 1H) ppm. ESI-MS
(m/z): Calcd for C31H23N3O(191Ir) (M+H+): 644.1442. Found:
644.1443. Elemental analysis was not carried out because the content
of iridium in 5 is >25%.
6: Yield = 62% (20 mg). Red color solid. mp > 300 °C. IR (ATR): ν
= 1606, 1538, 1477, 1417, 1314, 1135, 1030, 961, 788, 716, 627, 552
1
cm−1. H NMR (300 MHz, CDCl3) δ 8.89 (d, J = 8.8 Hz, 1H), 8.58
(d, J = 6.3 Hz, 1H), 8.49 (s, 1H), 7.89 (d, J = 8.4 Hz, 2H), 7.73 (t, J =
7.5 Hz, 2H), 7.63 (d, J = 8.0 Hz, 1H), 7.54 (d, J = 6.9 Hz, 2H), 7.33
(d, J = 8.8 Hz, 1H), 7.12 (s, 1H), 6.95−6.82 (m, 3H), 6.75 (d, J = 7.4
Hz, 2H), 6.39 (d, J = 6.7 Hz, 1H), 6.02 (d, J = 7.7 Hz, 1H), 2.84 (s,
6H), 2.24 (s, 6H), 2.14 (s, 3H) ppm. ESI-MS (m/z): Calcd for
C36H34N5O5S2(191Ir) (M+): 871.1602. Found: 871.1604. Anal. Calcd
for C36H34IrN5O5S2·0.25CHCl3: C, 48.22; H, 3.82; N, 7.76. Found: C,
48.60, H, 4.02; N, 7.49%.
7: Yield = 51% (20 mg). Red color solid. mp > 300 °C. IR (ATR): ν
= 1587, 1538, 1502, 1456, 1315, 1138, 1048, 962, 815, 788, 815, 788,
719, 676, 577, 554 cm−1. 1H NMR (300 MHz, CDCl3) δ 8.94 (s, 2H),
8.86 (d, J = 8.8 Hz, 1H), 8.17 (d, J = 8.3 Hz, 1H), 8.00 (d, J = 8.1 Hz,
1H), 7.87 (s, 2H), 7.73 (dd, J = 7.7, 5.6 Hz, 4H), 7.45−7.34 (m, 2H),
7.31 (s, 1H), 7.18 (d, J = 6.2 Hz, 1H), 6.77 (s, 2H), 6.23 (s, 1H), 5.99
(s, 1H), 2.82 (s, 6H), 2.13 (s, 6H), 2.01 (d, J = 1.9 Hz, 3H) ppm. ESI-
MS (m/z): Calcd for C36H34N5O3S(191Ir) (M+): 807.1988. Found:
807.1985. Anal. Calcd for C36H34IrN5O5S2·0.33CHCl3: C, 51.41; H,
4.08; N, 8.25. Found: C, 51.59, H, 4.00; N, 7.94%.
Figure 6. Chromaticity diagram showing the xy color coordinates of
11, 14, 19, 20, and 37+2 (CIE 1931). The xy color coordinates of
these complexes were calculated from their RGB values. For details,
see Table S1 in Supporting Information.
N-(Quinolin-8-yl)benzenesulfonamine (31). Yield = 57% (56 mg).
Off-white color solid. mp 120 °C. IR (ATR): ν = 3215, 1503, 1407,
1
1355, 1306, 1160, 1086, 926, 785, 716, 684, 568, 557 cm−1. H NMR
(300 MHz, CDCl3) δ 9.25 (s, 1H), 8.76 (dd, J = 4.2, 1.7 Hz, 1H), 8.10
(dd, J = 8.3, 1.6 Hz, 1H), 7.97−7.87 (m, 2H), 7.84 (dd, J = 6.3, 2.7 Hz,
1H), 7.45 (dd, J = 3.9, 2.5 Hz, 3H), 7.43−7.35 (m, 3H) ppm. EI-MS
(m/z): Calcd for C10H12N2O2S (M+): 284.0619. Found: 284.0616.
4-Bromo-N-(quinolin-8-yl)benzenesulfonamine (32). Yield = 49%
(62 mg). Off-white color solid. mp 218 °C. IR (ATR): ν = 3223, 1572,
1504, 1410, 1268, 1304, 1157, 1084, 796, 740, 668, 614, 553 cm−1. 1H
NMR (300 MHz, CDCl3) δ 9.23 (s, 1H), 8.76 (s, 1H), 8.12 (d, J = 8.2
Hz, 1H), 7.83 (d, J = 7.1 Hz, 1H), 7.77 (d, J = 8.7 Hz, 2H), 7.52−7.42
(m, 5H) ppm. EI-MS (m/z): Calcd for: C15H11BrN2O2S (M+):
361.9725. Found: 361.9724.
4-Methoxy-N-(quinolin-8-yl)benzenesulfonamine (33). Yield =
73% (80 mg). Gray color solid. mp 75 °C. IR (ATR): ν = 3267,
1593, 1504, 1470, 1412, 1363, 1259, 1150, 1085, 920, 824, 787, 667,
549 cm−1. 1H NMR (300 MHz, CDCl3) δ 9.20 (s, 1H), 8.76 (dd, J =
4.2, 1.7 Hz, 1H), 8.10 (dd, J = 8.3, 1.6 Hz, 1H), 7.91−7.75 (m, 3H),
7.53−7.34 (m, 3H), 6.92−6.70 (m, 2H), 3.76 (s, 3H) ppm. EI-MS
(m/z): Calcd for C16H14N2O3S (M+): 314.0725. Found: 314.0727.
N-(Quinolin-8-yl)quinoline-8-sulfonamine (34). Yield = 59% (69
mg). White color solid. mp 232 °C. IR (ATR): ν = 3165, 1501, 1469,
1411, 1269, 1306, 1167, 1144, 834, 768, 700, 588, 502 cm−1. 1H NMR
(300 MHz, CDCl3) δ 10.55 (s, 1H), 9.20−9.00 (m, 1H), 8.75−8.57
(m, 1H), 8.52 (d, J = 7.3 Hz, 1H), 8.21−8.03 (m, 1H), 8.04−7.83 (m,
3H), 7.64−7.48 (m, 1H), 7.46 (dd, J = 8.3, 4.3 Hz, 1H), 7.41−7.28
(m, 3H) ppm. EI-MS (m/z): Calcd for C18H13N3O2S (M+): 335.0728.
Found: 335.0722.
8: Yield = 66% (52 mg). Orange color solid. mp > 300 °C. IR
(ATR): ν = 1606, 1582, 1535, 1476, 1417, 1313, 1145, 1060, 970, 831,
1
754, 729, 667, 553 cm−1. H NMR (300 MHz, CDCl3) δ 8.92 (d, J =
8.8 Hz, 1H), 8.66−8.40 (m, 2H), 7.90 (dd, J = 8.0, 4.3 Hz, 2H), 7.79−
7.68 (m, 2H), 7.65 (d, J = 7.8 Hz, 1H), 7.57 (d, J = 7.8 Hz, 1H), 7.43
(d, J = 5.7 Hz, 1H), 7.38 (d, J = 7.5 Hz, 1H), 7.10 (ddd, J = 7.3, 5.8,
1.4 Hz, 1H), 6.97−6.83 (m, 3H), 6.82−6.71 (m, 2H), 6.42−6.33 (m,
1H), 5.99 (d, J = 7.6 Hz, 1H), 5.23 (q, J = 5.5 Hz, 1H), 4.46 (d, J = 5.4
Hz, 1H), 2.72 (d, J = 5.4 Hz, 2H), 2.15 (d, J = 7.0 Hz, 4H), 1.87 (d, J
= 5.5 Hz, 3H) ppm. ESI-MS (m/z): Calcd for C34H30N5O5S2(191Ir)
(M+): 843.1288. Found: 843.1286. Anal. Calcd for C34H30IrN5O5S2·
0.33CHCl3: C, 46.61; H, 3.46; N, 7.92. Found: C, 46.40, H, 3.18; N,
7.66%.
9: Yield = 50% (17 mg). Red color solid. mp > 300 °C. IR (ATR): ν
= 1604, 1553, 1474, 1415, 1335, 1294, 1267, 1208, 1159, 1060, 1028,
1
999, 820, 752, 681, 630, 560 cm−1. H NMR (300 MHz, CDCl3) δ
9.80 (d, J = 6.5 Hz, 1H), 8.02 (t, J = 6.5 Hz, 2H), 7.89−7.80 (m, 3H),
7.70−7.54 (m, 4H), 7.39 (d, J = 5.7 Hz, 1H), 7.33 (d, 6.2 Hz, 2H),
7.14 (d, J = 8.0 Hz, 1H), 7.08 (d, J = 5.0 Hz, 1H), 7.00 (t, J = 7.2 Hz,
2H), 6.91 (d, J = 3.8 Hz, 1H), 6.83−6.73 (m, 2H), 6.47 (d, J = 7.2 Hz,
1H), 6.32 (d, J = 7.6 Hz, 1H) ppm. ESI-MS (m/z): Calcd for
C31H22N3S (191Ir) (M+H+): 659.1134. Found: 659.1128. Elemental
analysis was not carried out because the content of iridium in 9 is
>25%.
10: Yield = 64% (16 mg). Red color solid. mp > 300 °C. IR (ATR):
ν = 1605, 1582, 1512, 1475, 1446, 1415, 1323, 1263, 1208, 1136, 1060,
Synthesis of Ir Complexes 5−21. A general method was used for
preparing all of complexes: di-μ-chloro-tetrakis[k2(C2,N)-2-
phenylpyridine]diiridium(III) 22 (1 equiv) was dissolved in a mixture
of CH2Cl2 and EtOH (4:1 ratio), and the 8-hydroxyquinoline
derivatives (2.2 equiv) and Et3N (45 equiv) were then added. The
reaction mixture was refluxed for 20 h under argon. After evaporation
of the solvent, the residue was washed with ethanol to remove
unreacted ligand, and the resulting product was purified by silica gel
1
1030, 945, 808, 728, 639, 570 cm−1. H NMR (300 MHz, CDCl3) δ
8.94 (s, 2H), 8.86 (d, J = 8.8 Hz, 1H), 8.49 (t, J = 3.2 Hz, 2H), 8.17 (d,
J = 8.3 Hz, 1H), 8.00 (d, J = 8.1 Hz, 1H), 7.87 (s, 2H), 7.76−7.70 (m,
4H), 7.45−7.34 (m, 2H), 7.31 (s, 1H), 7.18 (d, J = 6.2 Hz, 1H), 6.77
(s, 2H), 6.23 (s, 1H), 5.99 (s, 1H), 2.82 (s, 6H), 2.13 (s, 9H), 2.03 (s,
3H), 2.01 (s, 3H) ppm. ESI-MS (m/z): Calcd for
C46H42N5O5S2(191Ir) (M+): 999.2223. Found: 999.2208. Anal. Calcd
I
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 7. Molecular orbitals of 6, 11, 12, 14, and 19.
for C46H42IrN5O5S2: C, 55.18; H, 4.23; N, 6.99. Found: C, 55.25, H,
4.11; N, 6.67%.
Hz, 1H), 8.03 (s, 1H), 7.98 (d, J = 6.3 Hz, 2H), 7.84 (t, J = 8.7 Hz,
4H), 7.73 (d, J = 6.9 Hz, 2H), 7.63 (dd, J = 8.4, 4.9 Hz, 1H), 7.17−
7.06 (m, 2H), 7.01−6.74 (m, 4H), 6.27 (dd, J = 14.5, 6.5 Hz, 2H)
ppm. ESI-MS (m/z): Calcd for C31H24N4(191Ir) (M+): 643.1601.
Found: 643.1590. Elemental analysis was not carried out because the
content of iridium in 12 is >25%.
11: Yield = 92% (38 mg). Yellow color. mp > 300 °C. IR (ATR): ν
= 1586, 1501, 1443, 1375, 1311, 1287, 1139, 1110, 1085, 941, 813,
1
741, 672, 579 cm−1. H NMR (300 MHz, CDCl3) δ 9.05 (d, J = 6.5
Hz, 1H), 8.93 (d, 6.0 Hz, 1H), 8.87 (d, 6.9 Hz, 1H), 8.10 (d, J = 8.0
Hz, 1H), 8.04 (dd, J = 8.2, 3.3 Hz, 2H), 8.01−7.96 (m, 1H), 7.87−
7.72 (m, 2H), 7.73−7.58 (m, 4H), 7.56 (dd, J = 4.9, 1.5 Hz, 1H), 7.44
(t, J = 8.1 Hz, 1H), 7.29 (d, J = 6.6 Hz, 2H), 7.17−7.04 (m, 4H), 7.01
(d, J = 6.5 Hz, 1H), 6.92 (t, J = 7.4 Hz, 1H), 6.82 (d, J = 6.7 Hz, 1H),
6.71 (dd, J = 15.3, 7.5 Hz, 3H), 6.16 (d, J = 2.8 Hz, 2H), 2.06 (s, 3H),
2.01 (s, 3H) ppm. ESI-MS (m/z): Calcd for C47H35N4O2S(191Ir)
(M+): 910.2081. Found: 910.2097. Anal. Calcd for C47H35IrN4O2S·
CH2Cl2: C, 57.82; H, 3.74; N, 5.62. Found: C, 57.77, H, 3.49; N,
5.66%.
12: Yield = 79% (19 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 2892, 1608, 1582, 1477, 1421, 1374, 1315, 1270, 1211,
1156, 1062, 1031, 828, 785, 730, 629, 556 cm−1. 1H NMR (300 MHz,
DMSO-d6) δ 8.69−8.56 (m, 2H), 8.35−8.24 (m, 1H), 8.19 (d, J = 8.3
13: Yield = 71% (24 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1605, 1585, 1653, 1502, 1476, 1311, 1288, 1268, 1126,
1
1062, 1029, 956, 856, 826, 747, 665, 544, 520 cm−1. H NMR (300
MHz, CDCl3) δ 9.24 (d, J = 4.9 Hz, 1H), 8.16 (d, J = 7.3 Hz, 1H),
8.09−8.00 (m, 1H), 7.92 (d, J = 7.9 Hz, 1H), 7.81 (d, J = 8.3 Hz, 1H),
7.74 (dd, J = 4.9, 1.5 Hz, 1H), 7.68−7.58 (m, 4H), 7.53 (t, J = 8.1 Hz,
1H), 7.25 (s, 1H), 7.21−7.10 (m, 2H), 7.06 (t, J = 6.6 Hz, 1H), 6.83−
6.73 (m, 5H), 6.32 (d, J = 7.6 Hz, 1H), 6.23 (d, J = 7.5 Hz, 1H), 2.27
(s, 3H) ppm. ESI-MS (m/z): Calcd for C32H25N4O2S(191Ir) (M+):
720.1299. Found: 720.1303. Anal. Calcd for C32H25IrN4O2S·CHCl3:
C, 47.12; H, 3.12; N, 6.66. Found: C, 47.07, H, 2.73; N, 6.55%.
14: Yield = 46% (20 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1603, 1582, 1562, 1474, 1416, 1380, 1312, 1262, 1193,
J
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Table 6. Calculated Triplet Transition States and Selected Frontier Orbitals of Compounds 6, 8, 10−16, 18−21
a
wavelength (nm) expt
E (eV) expt
E (eV) TD-DFT
state
assignment
main transition character
3
6
587
588
600
2.11
2.10
2.07
2.23
2.24
2.10
T1
T1
T1
HOMO−1→LUMO (80%)
HOMO−1→LUMO (76%)
HOMO→LUMO (54%)
HOMO→LUMO+1 (10%)
HOMO→LUMO (14%)
HOMO−1→LUMO (36%)
HOMO→LUMO (98%)
HOMO→LUMO+1 (20%)
HOMO→LUMO+2 (28%)
HOMO→LUMO (88%)
HOMO→LUMO+1 (44%)
HOMO→LUMO+2 (18%)
HOMO→LUMO (88%)
HOMO→LUMO+1 (36%)
HOMO→LUMO+2 (20%)
HOMO→LUMO (92%)
HOMO→LUMO+1 (48%)
HOMO→LUMO+2 (20%)
HOMO→LUMO (92%)
HOMO→LUMO+1 (26%)
HOMO→LUMO+2 (12%)
HOMO→LUMO (84%)
HOMO→LUMO+1 (84%)
HOMO→LUMO (86%)
HOMO→LUMO+1 (36%)
HOMO→LUMO+2 (16%)
HOMO→LUMO (79%)
HOMO→LUMO+1 (68%)
HOMO→LUMO+2 (12%)
3MLquinCT + Lquin
C
C
3
8
3MLquinCT + Lquin
3
10
3MLmpiqCT + LquinLmpiqCT
3
11
602
2.06
2.12
T1
3MLmpiqCT + LquinLmpiqCT
3Lmpiq
C
3
12
13
557
500
2.22
2.47
2.09
2.56
T1
T1
3MLppyCT + LppyLquinCT
3
3MLppyCT + LquinLppyCT
3
3
14
15
16
18
617
496
2.00
2.49
1.90
2.51
T1
T2
3MLquinCT + LquinC + ILquinCT
3
3MLppyCT + LquinLppyCT
3
3
611
496
2.03
2.50
1.91
2.51
T1
T2
3MLquinCT + LquinC + ILquinCT
3
3MLppyCT + LquinLppyCT
3
3
622
500
1.99
2.47
1.89
2.52
T1
T2
3MLquinCT + LquinC + ILquinCT
3
3MLppyCT + LquinLppyCT
3
3
617
487
2.01
2.54
1.89
2.53
T1
T2
3MLquinCT + LquinC + ILquinCT
3
3MLmppyCT + LquinLmppyCT
3
3
19
20
613
474
617
476
2.02
2.61
2.01
2.60
2.08
2.76
1.84
2.58
T1
T2
T1
T2
3MLquinCT + LquinC + ILquinCT
3MLF2ppyCT + LquinLF2ppyCT
3
3
3
3MLquinCT + LquinC + ILquinCT
3MLF2ppyCT + LquinLF2ppyCT
3
3
3
21
615
494
2.01
2.50
1.90
2.47
T1
T2
3MLquinCT + LquinC + ILquinCT
3MLF2ppyCT + LquinLF2ppyCT
3
a
Major contributions defined as >10% contribution to the transition.
Scheme 5. Proposed Energy Diagram of 19
K
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 8. Time-resolved emission spectra of 19 (10 μM) in DMSO at 298 K, excitation 371 nm. (inset) Emission decay curves at 474, 493, and 613
nm.
(m/z): Calcd for C38H29N4O3S (191Ir) (M+): 812.1561. Found:
812.1563. Anal. Calcd for C38H29IrN4O3S: C, 56.07; H, 3.59; N, 6.88.
Found: C, 55.69, H, 3.27; N, 6.74%.
a
Table 7. Lifetimes of 14 and 19 in Degassed Dimethyl
Sulfoxide at 298 K
comp
emission (nm)
lifetime τ (μs)
17: Yield = 72% (45 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1604, 1581, 1561, 1496, 1475, 1456, 1417, 1380, 1309,
1286, 1262, 1191, 1119, 1061, 944, 847, 759, 593. 576 cm−1. 1H NMR
(300 MHz, CDCl3) δ 9.58 (d, J = 5.1 Hz, 1H), 9.30 (d, J = 7.4 Hz,
1H), 8.41−8.33 (m, 1H), 8.03 (dd, J = 8.3, 1.5 Hz, 1H), 7.81 (dd, J =
8.3, 1.8 Hz, 1H), 7.72 (t, J = 8.2 Hz, 2H), 7.65−7.56 (m, 2H), 7.52−
7.49 (m, 2H), 7.22 (d, J = 6.9 Hz, 1H), 7.17−6.88 (m, 8H), 6.88−6.72
(m, 4H), 6.66 (t, J = 6.8 Hz, 1H), 6.38 (s, 1H), 5.93 (s, 1H), 5.83 (d, J
= 7.7 Hz, 1H) ppm. ESI-MS (m/z): Calcd for C40H28N5O2S(191Ir) (M
+H+): 834.1642. Found: 834.1642. Anal. Calcd for C40H28IrN5O2S·
0.5CHCl3: C, 54.37; H, 3.21; N, 7.83. Found: C, 54.70, H, 3.07; N,
7.62%.
b
14
496 (HEB)
617 (LEB)
474 (HEB)
493 (HEB)
613 (LEB)
1.7 (100%)
1.3 (4%), 12 (96%)
1.9 (100%)
19
1.9 (100%)
1.8 (2%), 17 (98%)
a
Determined from emission decay curves monitored at each emission
b
wavelength. Excitation at 371 nm. Values in parentheses are
distribution of each decay component in the emission intensity at
the indicated wavelength.
1139, 1115, 1084, 945, 844, 735, 581 cm−1. H NMR (300 MHz,
1
18: Yield = 75% (21 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1590, 1548, 1460, 1427, 1311, 1275, 1213, 1143, 1108,
CDCl3) δ 9.23 (d, J = 8.2 Hz, 1H), 8.26 (d, J = 8.4 Hz, 1H), 8.02 (d, J
= 8.3 Hz, 1H), 7.76 (dd, J = 7.8, 4.2 Hz, 2H), 7.69−7.59 (m, 2H), 7.56
(d, J = 7.3 Hz, 2H), 7.49−7.36 (m, 2H), 7.13 (dd, J = 8.0, 3.3 Hz, 5H),
7.03 (d, J = 7.8 Hz 1H), 6.99−6.85 (m, 3H), 6.92−6.66 (m, 5H), 6.37
(d, J = 8.8 Hz, 1H), 6.15 (d, J = 7.2 Hz, 1H) ppm. ESI-MS (m/z):
Calcd for C37H27N4O2S(191Ir) (M+): 782.1451. Found: 782.1455.
Anal. Calcd for C37H27IrN4O2S·0.33CHCl3: C, 55.21; H, 3.43; N, 6.90.
Found: C, 55.60, H, 3.14; N, 6.93%.
15: Yield = 75% (48 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1604, 1571, 1502, 1474, 1417, 1386, 1297, 1268, 1158,
1136, 1058, 1028, 946, 858, 733, 602, 568 cm−1. 1H NMR (300 MHz,
CDCl3) δ 9.29 (d, J = 5.7 Hz, 1H), 8.45 (d, J = 8.1 Hz, 1H), 8.05 (d, J
= 8.3 Hz, 2H), 7.79 (d, J = 8.5 Hz, 2H), 7.72−7.66 (m, 2H), 7.62−
7.51 (m, 2H), 7.39 (s, 2H), 7.23−7.09 (m, 4H), 7.00 (d, J = 8.5 Hz,
2H), 6.95−6.86 (m, 2H), 6.85−6.73 (m, 2H), 6.69 (s, 2H), 6.38 (d, J
= 6.9 Hz, 1H), 6.06 (d, J = 7.5 Hz, 1H) ppm. ESI-MS (m/z): Calcd for
C37H26BrN4O2S (191Ir) (M+): 860.0560. Found: 860.0570. Anal. Calcd
for C37H26IrN4O2S·CHCl3: C, 46.47; H, 2.77; N, 5.70. Found: C,
46.69, H, 2.52; N, 5.66%.
1
1085, 1036, 944, 860, 819, 774, 744, 713, 690, 582 cm−1. H NMR
(300 MHz, CDCl3) δ 9.12 (d, J = 4.9 Hz, 1H), 8.17 (d, J = 8.4 Hz,
1H), 8.01 (d, J = 8.3 Hz, 1H), 7.79 (d, J = 5.1 Hz, 1H), 7.67−7.55 (m,
3H), 7.55−7.45 (m, 3H), 7.45−7.37 (m, 2H), 7.18 (d, J = 8.2 Hz,
3H), 7.12 (dd, J = 8.1, 4.9 Hz, 2H), 7.01−6.91 (m, 3H), 6.63 (s, 1H),
6.51 (dd, J = 8.3, 2.6 Hz, 1H), 6.44 (dd, J = 8.5, 2.6 Hz, 1H), 5.83 (d, J
= 2.6 Hz, 1H), 5.72 (d, J = 2.6 Hz, 1H), 3.57 (s, 3H), 3.55 (s, 3H)
ppm. ESI-MS (m/z): Calcd for C39H31N4O4S(191Ir) (M+): 842.1666.
Found: 842.1674. Anal. Calcd for C39H31IrN4O2S·CHCl3: C, 48.87; H,
3.35; N, 5.82. Found: C, 48.59, H, 3.73; N, 5.86%.
19: Yield = 97% (68 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1601, 1569, 1477, 1459, 1401, 1310, 1295, 1247, 1161,
1
1143, 1086, 987, 945, 842, 823, 754, 715, 689, 567 cm−1. H NMR
(300 MHz, CDCl3) δ 9.20 (dd, J = 5.9, 1.0 Hz, 1H), 8.27 (dd, J = 8.2,
0.8 Hz, 1H), 8.19 (d, J = 8.3 Hz, 1H), 8.08 (dt, J = 7.7, 3.9 Hz, 2H),
7.74 (dd, J = 4.9, 1.5 Hz, 1H), 7.69 (t, J = 8.2 Hz, 1H), 7.60 (t, J = 8.4
Hz, 1H), 7.49 (t, J = 8.1 Hz, 1H), 7.25−7.22 (m, 1H), 7.22−7.12 (m,
4H), 7.06 (ddd, J = 7.3, 5.9, 1.3 Hz, 1H), 7.00 (t, J = 7.8 Hz, 2H),
6.80−6.70 (m, 1H), 6.49 (t, J = 7.9 Hz, 1H), 6.52−6.43 (m, 1H),
6.37−6.25 (m, 1H), 5.72 (dd, J = 8.1, 2.3 Hz, 1H), 5.58 (dd, J = 8.2,
2.3 Hz, 1H) ppm. ESI-MS (m/z): Calcd for C37H23F4N4O2S(191Ir)
(M+): 854.1078. Found: 854.1066. Elemental analysis was not carried
out because the content of fluorine in 19 is >25%.
16: Yield = 64% (38 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1603, 1581, 1497, 1475, 1257, 1418, 1381, 1311, 1253,
1160, 1138, 1088, 1029, 942, 823, 761, 679, 628, 573 cm−1. H NMR
1
(300 MHz, CDCl3) δ 9.26 (d, J = 6.0 Hz, 1H), 8.26 (d, J = 8.2 Hz,
1H), 8.02 (d, J = 8.3 Hz, 1H), 7.84−7.69 (m, 3H), 7.69−7.52 (m,
4H), 7.47 (t, J = 8.1 Hz, 2H), 7.17−7.07 (m, 2H), 7.03 (dd, J = 5.5, 3.4
Hz, 3H), 6.92 (t, J = 7.0 Hz, 1H), 6.87−6.61 (m, 4H), 6.49−6.31 (m,
3H), 6.15 (d, J = 7.4 Hz, 1H), 3.74 (s, J = 4.7 Hz, 3H) ppm. ESI-MS
20: Yield = 69% (37 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1599, 1573, 1497, 1477, 1402, 1310, 1291, 1260, 1246,
1
1136, 1101, 1085, 985, 945, 859, 825, 782, 753, 663, 574 cm−1. H
L
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Φ = Φ(η 2ArIs)/(η 2AsIr)
NMR (300 MHz, CDCl3) δ 9.24 (d, J = 5.7 Hz, 1H), 8.31 (d, J = 8.1
Hz, 1H), 8.20 (d, J = 7.5 Hz, 1H), 8.07 (s, 2H), 7.77−7.56 (m, 3H),
7.50 (t, J = 8.1 Hz, 1H), 7.24−7.12 (m, 3H), 7.11−6.97 (m, 3H), 6.77
(t, J = 6.2 Hz, 1H), 6.46 (d, J = 8.1 Hz, 3H), 6.36 (m, 1H), 5.73 (d, J =
8.0 Hz, 1H), 5.56 (d, J = 6.5 Hz, 1H), 3.75 (d, J = 6.1 Hz, 3H) ppm.
ESI-MS (m/z): Calcd for C38H25F4N4O3S(191Ir) (M+): 884.1184.
Found: 884.1206. Elemental analysis was not performed because the
content of fluorine in 20 is >25%.
(1)
s
r
s
r
The luminescence lifetimes of sample solutions of Ir(III) complexes in
degassed DMSO at 298 K were measured on a TSP1000-M-PL
(Unisoku, Osaka, Japan) instrument by using THG (355 nm) of
Nd:YAG laser, Minilite I (Continuum, CA, USA) as excitation source
and long wave pass filters (435 nm, 475 or 550 nm). The signals were
monitored with an R2949 photomultiplier. Data were analyzed using a
single exponential decay equation. Sample solutions in quartz cuvettes
equipped with Teflon septum screw caps were degassed by bubbling
Ar through the solution for 20 min prior to measuring the lifetime.
Time-Resolved Emission Spectroscopy. Emission decay was
measured at emission maxima corresponding to the emission from
Ir(III) complexes by the time-dependent single photon counting
method using a FluoroCube 1000U−S spectrofluorometer under 371
nm photoexcitation (NanoLED-440L, HORIBA) with a TBX-04
detector at 298 K.
21: Yield = 49% (26 mg). Yellow color solid. mp > 300 °C. IR
(ATR): ν = 1601, 1568, 1557, 1504, 1476, 1402, 1310, 1245, 1291,
1
1126, 1101, 985, 957, 843, 824, 748, 568, 548, 523 cm−1. H NMR
(300 MHz, CDCl3) δ 9.15 (d, J = 4.8 Hz, 1H), 8.34 (d, J = 8.6 Hz,
1H), 8.21 (d, J = 8.1 Hz, 1H), 8.13 (dd, J = 7.8, 4.6 Hz, 2H), 7.80−
7.64 (m, 3H), 7.56 (t, J = 8.1 Hz, 1H), 7.25 (s, 1H), 7.22 (dd, J = 8.3,
3.4 Hz, 2H), 7.09 (t, J = 6.7 Hz, 1H), 6.80 (t, J = 6.7 Hz, 1H), 6.54−
6.28 (m, 2H), 5.67 (ddd, J = 15.5, 8.7, 2.3 Hz, 2H), 2.29 (s, J = 6.5 Hz,
3H) ppm. ESI-MS (m/z): Calcd for C32H21F4N4O2S(191Ir) (M+):
792.0917. Found: 792.0910. Elemental analysis was not carried out
because the content of fluorine in 21 is >25%.
X-ray Data Collection and Refinement. Single-crystal X-ray
studies were performed on a Bruker APEX II CCD diffractometer
equipped with a Bruker Instruments low-temperature attachment.
Data were collected at 100 K using graphite-monochromated Mo Kα
radiation (λ = 0.710 73 Å). The frames were indexed, integrated, and
scaled using the SMART and SAINT software packages.33 An
empirical absorption correction was applied to the collected reflections
with SADABS34 using XPREP.35 All of the structures were solved by
the direct method using the program SHELXS-97 and were refined on
F2 by the full-matrix least squares technique using the SHELXL-97
program package.36 All non-hydrogen atoms were refined anisotropi-
cally in the structure.
Crystal Data for 14. C37H27IrN4O2S·CHCl3, Mr = 903.27,
monoclinic, P21/n, a = 19.194(5), b = 9.114(5), c = 19.709(5) Å, α
= 90, β = 101.926(5), γ = 90°, V = 3374(2) Å3, Z = 4, ρcalc= 1.778
g.cm−3, R = 0.0280 (for 5349 reflection with I > 2σ(I)), Rw = 0.0656
(for 6166 reflections), GOF = 0.996. CCDC 1439264 contains the
supplementary crystallographic data for the compound. Additional
crystallographic information is available in the Supporting Information.
Crystal Data for 19. C37H23F4IrN4O2S·CHCl3, Mr = 975.22,
ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.5b02872. Related crystallographic data can be obtained
free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
■
S
UV−vis spectra of 11−21, excitation spectra of 11, 14,
19, emission spectra of 14 in different solvents, emission
spectra of 19 at different temperatures, solid-state
emission spectra of 13−17, emission spectra of 11, 14,
19 of doped PMMA film, emission decay graphs of 11
and 14. (PDF)
X-ray crystallographic files of 14, 19, and 20. (CIF)
AUTHOR INFORMATION
Corresponding Author
*E-mail: shinaoki@rs.noda.tus.ac.jp. Phone: +81-4-7121-3670.
■
Triclinic, P1, a = 11.477(5), b = 13.075(5), c = 13.777(5) Å, α =
̅
Notes
73.813(5), β = 71.921(5), γ = 66.201(5)°, V = 1770.0(12) Å3, Z = 2,
ρcalc = 1.830 g.cm−3, R = 0.0435 (for 6326 reflection with I > 2σ(I)),
Rw = 0.1096 (for 7103 reflections), GOF = 1.038. CCDC 1439265
contains the supplementary crystallographic data for the compound.
Crystal Data for 20. C38H25F4IrN4O3S, Mr = 885.88, monoclinic,
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work is supported by the Grants-in-Aid from the Ministry
of Education, Culture, Sports, Science and Technology (MEXI)
of Japan (No. 26860016 for Y.H. and Nos. 24659055 and
24640156 for S.A). We thank Mr. S. Ootsu and Mr. N. Ueda
(Konica Minolta Holding, Inc. Japan) for helpful discussions.
We wish to acknowledge Mrs. F. Hasegawa (Faculty of
Pharmaceutical Science, Tokyo University of Science) for
measurement of mass spectra and Ms. T. Mastsuo (Research
Institute for Science and Technology, Tokyo University of
Science) for the X-ray single-crystal structure analysis.
P1, a = 10.355(5), b = 11.129(5), c = 16.199(5) Å, α = 85.020, β =
̅
77.980(5), γ = 84.218(5) °, V = 1812(13) Å3, Z = 2, ρcalc= 1.623 g·
cm−3, R = 0.0336 (for 5874 reflection with I > 2σ(I)), Rw = 0.0826
(for 6602 reflections), GOF = 1.042. CCDC 1439266 contains the
supplementary crystallographic data for the compound.
Measurements of Ultraviolet−Visible Absorption and
Luminescence Spectra. UV−vis spectra were recorded on a
JASCO V-550 UV−vis spectrophotometer, and emission spectra
were recorded on a JASCO FP-6200 and FP-6500 spectrofluorometer,
respectively. Sample solutions in quartz cuvettes equipped with Teflon
septum screw caps were degassed by bubbling Ar through the solution
for 10 min prior to making the luminescence measurements. The
quantum yields for luminescence (Φ) were determined by comparison
with the integrated corrected emission spectrum of Ir(mpiq)3 (2) (Φ
= 0.26).22 Equation 1 was used to calculate the emission quantum
yields, in which Φs and Φr denote the quantum yields of the sample
and reference compound, ηs and ηr are the refractive indexes of the
solvents used for the measurements of the sample and the reference
(1.477 for DMSO (ηs)), As and Ar are the absorbance of the sample
and the reference, and Is and Ir stand for the integrated areas under the
emission spectra of the sample and reference, respectively (all of the Ir
compounds were excited at 366 nm for luminescence measurements in
this study). For the determination of Φs in mixed-solvent systems, the
η values of the main solvents were used for the calculation.
REFERENCES
■
(1) Forrest, S. R.; Thompson, M. E.; Baldo, M. A. Nature 2000, 403,
750−753.
(2) (a) Tamayo, A. B.; Alleyne, B. D.; Djurovich, P. I.; Lamansky, S.;
Tsyba, I.; Ho, N. N.; Bau, R.; Thompson, M. E. J. Am. Chem. Soc.
2003, 125, 7377−7387. (b) Swanick, K. N.; Ladouceur, K.; Zysman-
Colman, E.; Ding, Z. Angew. Chem., Int. Ed. 2012, 51, 11079−11082.
(c) Hisamatsu, Y.; Aoki, S. Eur. J. Inorg. Chem. 2011, 2011, 5360−
5369. (d) Wong, W.-Y.; Ho, C.-L. Coord. Chem. Rev. 2009, 253, 1709−
1758. (e) Ulbricht, C.; Beyer, B.; Friebe, C.; Winter, A.; Schubert, U. S.
Adv. Mater. 2009, 21, 4418−4441. and reference cited therein.
(f) Sudhakar, M.; Djurovich, P. I.; Hogen-Esch, T. E.; Thompson, M.
E. J. Am. Chem. Soc. 2003, 125, 7796−7797. (g) Chi, Y.; Chou, P.-T.
M
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Chem. Soc. Rev. 2010, 39, 638−655. (h) You, Y.; Park, S. Y. Dalton
Trans. 2009, 1267−1282.
Picone, A. L.; Todescato, F.; Williams, J. A. G. Dalton Trans. 2015, 44,
15712−15720.
(7) (a) Hisamatsu, Y.; Shibuya, A.; Suzuki, N.; Suzuki, T.; Abe, R.;
Aoki, S. Bioconjugate Chem. 2015, 26, 857−879. (b) Liu, Z.; Salassa, L.;
Habtemariam, A.; Pizarro, A. M.; Clarkson, G. J.; Sadler, P. J. Inorg.
Chem. 2011, 50, 5777−5783. (c) Liu, Z.; Sadler, P. J. Acc. Chem. Res.
2014, 47, 1174−1185.
(8) (a) Huo, H.; Shen, X.; Wang, C.; Zhang, L.; Rose, P.; Chen, L.-
N.; Harms, K.; Marsch, M.; Hilt, G.; Meggers, E. Nature 2014, 515,
100−103. (b) Ma, J.; Ding, X.; Hu, Y.; Huang, Y.; Gong, L.; Meggers,
E. Nat. Commun. 2014, 5, 5531. (c) Chen, L-An.; Tang, X.; Xi, J.; Xu,
W.; Gong, L.; Meggers, E. Angew. Chem., Int. Ed. 2013, 52, 14021−
14025.
(9) D’Andrade, B. W.; Forrest, R. S. Adv. Mater. 2004, 16, 1585−
1595.
(10) (a) Sun, C.-Y.; Wang, X.-L.; Zhang, X.; Qin, C.; Li, P.; Su, Z.-
M.; Zhu, D.-X.; Shan, G.-G.; Shao, K.-Z.; Wu, H.; Li, J. Nat. Commun.
2013, 4, 2717. (b) Farinola, G. M.; Ragni, R. Chem. Soc. Rev. 2011, 40,
3467−3482.
(11) (a) Yeh, Y.-S.; Cheng, Y.-M.; Chou, P.-T.; Lee, G.; Yang, C.-H.;
Chi, Y.; Shu, C.-F.; Wang, C.-H. ChemPhysChem 2006, 7, 2294−2297.
(b) Lee, Y. H.; Park, G. Y.; Kim, Y. S. J. Korean Phys. Soc. 2007, 50,
1722−1728. (c) Lo, K.K.-W.; Zhang, K. Y.; Leung, S.-K.; Tang, M.-C.
Angew. Chem., Int. Ed. 2008, 47, 2213−2216. (d) You, Y.; Han, Y.; Lee,
Y.-M.; Park, S. Y.; Nam, W.; Lippard, S. J. J. Am. Chem. Soc. 2011, 133,
11488−11491. (e) You, Y.; Lee, S.; Kim, T.; Ohkubo, K.; Chae, W.-S.;
Fukuzumi, S.; Nam, W.; Lippard, S. J. J. Am. Chem. Soc. 2011, 133,
18328−18342. (f) Ladouceur, S.; Donato, L.; Romain, M.;
Mudraboyina, B. P.; Johansen, M. B.; Wisner, J. A.; Zysman-
Colman, E. Dalton Trans. 2013, 42, 8838−8847. (g) Zhang, K. Y.;
Liu, H.-W.; Tang, M.-C.; Choi, A. W.-T.; Zhu, N.; Wei, X.-G.; Lau, K.-
C.; Lo, K. K.-W. Inorg. Chem. 2015, 54, 6582−6593.
(12) (a) Tang, C. W.; Van-Slyke, S. A. Appl. Phys. Lett. 1987, 51,
913−915. (b) Wang, S. Coord. Chem. Rev. 2001, 215, 79−98.
(13) (a) Mishra, A.; Nayak, P. K.; Periasamy, N. Tetrahedron Lett.
2004, 45, 6265−6268. (b) Li, L.; Xu, B. Tetrahedron 2008, 64, 10986−
10995. (c) Fazaeli, Y.; Amini, M. M.; Mohajerani, E.; Sharbatdaran,
M.; Torabi, N. J. Colloid Interface Sci. 2010, 346, 384−390.
(14) (a) Perez-Bolivar, C.; Montes, V. A.; Anzenbacher, P., Jr. Inorg.
Chem. 2006, 45, 9610−9612. (b) Pohl, R.; Montes, V. A.; Shinar, J.;
Anzenbacher, P., Jr J. Org. Chem. 2004, 69, 1723−1725. (c) Pohl, R.;
Anzenbacher, P., Jr Org. Lett. 2003, 5, 2769−2772.
(15) (a) Kappaun, S.; Sax, S.; Eder, S.; Moller, K. C.; Waich, K.;
Niedermair, F.; Saf, R.; Mereiter, K.; Jacob, J.; Mullen, K.; List, E. J.
W.; Slugovc, C. Chem. Mater. 2007, 19, 1209−1211. (b) Kappaun, S.;
Eder, S.; Sax, S.; Mereiter, K.; List, E. J. W.; Slugovc, C. Eur. J. Inorg.
Chem. 2007, 2007, 4207−4215.
(16) (a) Song, Y.; Xu, H.; Chen, W.; Zhan, P.; Liu, X.
MedChemComm 2015, 6, 61−74. (b) Prajapati, S. M.; Patel, K. D.;
Vekariya, R. H.; Panchal, S. N.; Patel, H. D. RSC Adv. 2014, 4, 24463−
24476. (c) Pandeya, S. N.; Tyagi, A. Int. J. Pharm. Pharmaceu. Sci.
2011, 3, 53−61. (d) Amit, C.; Payal, C.; Kuldeep, K.; Mansimran, S.;
Sunaina; Poonam; Kuldeep, S. Can. Open Pharm. J. 2014, 1, 1−12.
(e) Gopaul, K.; Shintre, S. A.; Koorbanally, N. A. Anti-Cancer Agents
Med. Chem. 2015, 15, 631−646.
(3) (a) Zhuang, J.; Li, W.; Wu, W.; Song, M.; Su, W.; Zhou, M.; Cui,
Z. New J. Chem. 2015, 39, 246−253. (b) Bolink, H. J.; De Angelis, F.;
Baranoff, E.; Klein, C.; Fantacci, S.; Coronado, E.; Sessolo, M.;
Kalyanasundaram, K.; Gratzel, M.; Nazeeruddin, Md. K. Chem.
Commun. 2009, 4672−4674. (c) Lowry, M. S.; Bernhard, S. Chem. -
Eur. J. 2006, 12, 7970−7977. (d) Friend, R. H.; Gymer, R. W.;
Holmes, A. B.; Burroughes, J. H.; Marks, R. N.; Taliani, C.; Bradley, D.
D. C.; Dos Santos, D. A.; Brdas, J. L.; Lgdlund, M.; Salaneck, W. R.
Nature 1999, 397, 121−128.
(4) (a) Zhao, Q.; Huang, C.; Li, F. Chem. Soc. Rev. 2011, 40, 2508−
2524. (b) Lo, K. K.-W.; Louie, M.-W.; Zhang, K. Y. Coord. Chem. Rev.
2010, 254, 2603−2622. (c) Zhang, K. Y.; Li, S. P.-Y.; Zhu, N.; Or, I.
W.-S.; Cheung, M. S.-H.; Lam, Y.-W.; Lo, K.K.-W. Inorg. Chem. 2010,
49, 2530−2540. (d) Leung, S.-K.; Kwok, K. Y.; Zhang, K. Y.; Lo, K.K.-
W. Inorg. Chem. 2010, 49, 4984−4995. (e) Zhang, K. Y.; Liu, H.-W.;
Fong, T. T.-H.; Chen, X.-G.; Lo, K.K.-W. Inorg. Chem. 2010, 49,
5432−5443. (f) Zhao, Q.; Yu, M.; Shi, L.; Liu, S.; Li, C.; Shi, M.; Zhou,
Z.; Huang, C.; Li, F. Organometallics 2010, 29, 1085−1091.
(g) DeRosa, M. C.; Hodgson, D. J.; Enright, G. D.; Dawson, B.;
Evans, C. E. B.; Crutchley, R. J. J. Am. Chem. Soc. 2004, 126, 7619−
7626. (h) You, Y.; Cho, S.; Nam, W. Inorg. Chem. 2014, 53, 1804−
1815. and reference cited therein. (i) Patra, M.; Gasser, G.
ChemBioChem 2012, 13, 1232−1252. (j) You, Y.; Nam, W. Chem.
Soc. Rev. 2012, 41, 7061−7084. (k) Lo, K. K.-W.; Tso, K. K.-S. Inorg.
Chem. Front. 2015, 2, 510−524. (l) Lo, K. K.-W.; Zhang, K. Y. RSC
Adv. 2012, 2, 12069−12083. (m) Baggaley, E.; Weinstein, J. A.;
Williams, J. A. G. Coord. Chem. Rev. 2012, 256, 1762−1785.
(5) (a) Aoki, S.; Matsuo, Y.; Ogura, S.; Ohwada, H.; Hisamatsu, Y.;
Moromizato, S.; Shiro, M.; Kitamura, M. Inorg. Chem. 2011, 50, 806−
818. (b) Moromizato, S.; Hisamatsu, Y.; Suzuki, T.; Matsuo, Y.; Abe,
R.; Aoki, S. Inorg. Chem. 2012, 51, 12697−12706. (c) Nakagawa, A.;
Hisamatsu, Y.; Moromizato, S.; Kohno, M.; Aoki, S. Inorg. Chem. 2014,
53, 409−422. (d) Kando, A.; Hisamatsu, Y.; Ohwada, H.; Itoh, T.;
Moromizato, S.; Kohno, M.; Aoki, S. Inorg. Chem. 2015, 54, 5342−
5357. (e) Licini, M.; Gareth Williams, J. A. Chem. Commun. 1999,
1943−1944. (f) Arm, K. J.; Leslie, W.; Williams, J. A. G. Inorg. Chim.
Acta 2006, 359, 1222−1232. (g) Chen, Y.; Zhang, A.; Liu, Y.; Wang,
K. J. Organomet. Chem. 2011, 696, 1716−1722. (h) Weng, J.; Mei, Q.;
Jiang, W.; Fan, Q.; Tong, B.; Ling, Q.; Huang, W. Analyst 2013, 138,
1689−1699. (i) He, L.; Tan, C.-P.; Ye, R.-R.; Zhao, Y.-Z.; Liu, Y.-H.;
Zhao, Q.; Ji, L.-N.; Mao, Z.-W. Angew. Chem., Int. Ed. 2014, 53,
12137−12141. (j) Zhang, Q.; Zhou, M. Talanta 2015, 131, 666−671.
(k) Murphy, L.; Congreve, A.; Palsson, L.-O.; Williams, J. A. G. Chem.
Commun. 2009, 46, 8743−8745. (l) Goldstein, D. C.; Cheng, Y. Y.;
Schmidt, T. W.; Bhadbhade, M.; Thordarson, P. Dalton Trans. 2011,
40, 2053−2061.
(6) (a) Liu, C.; Lv, X.; Xing, Y.; Qiu, J. J. Mater. Chem. C 2015, 3,
8010−8017. (b) Marín-Suar
́
ez, M.; Curchod, B. F. E.; Tavernelli, I.;
Rothlisberger, U.; Scopelliti, R.; Jung, I.; Di Censo, D.; Gratzel, M.;
̈
́ ́ ́ ́
Fernandez-Sanchez, J. F.; Fernandez-Gutierrez, A.; Nazeeruddin, M.
K.; Baranoff, E. Chem. Mater. 2012, 24, 2330−2338. (c) Takizawa, S.;
Aboshi, R.; Murata, S. Photochem. Photobiol. Sci. 2011, 10, 895−903.
(d) Gao, R.; Ho, D. G.; Hernandez, B.; Selke, M.; Murphy, D.;
Djurovich, P. I.; Thompson, M. E. J. Am. Chem. Soc. 2002, 124,
14828−14829. (e) Sun, J.; Zhao, J.; Guo, H.; Wu, W. Chem. Commun.
2012, 48, 4169−4171. (f) Xue, F.; Lu, Y.; Zhou, Z.; Shi, M.; Yan, Y.;
Yang, H.; Yang, S. Organometallics 2015, 34, 73−77. (g) Li, S. P.-Y.;
Lau, C. T.-S.; Louie, M.-W.; Lam, Y.-W.; Lo, K. K.-W. Biomaterials
2013, 34, 7519−7532. (h) Djurovich, P. I.; Murphy, D.; Thompson,
M. E.; Hernandez, B.; Gao, R.; Hunt, P. L.; Selke, M. Dalton Trans.
2007, 34, 3763−3770. (i) Ashen-Garry, D.; Selke, M. Photochem.
Photobiol. 2014, 90, 257−274. (j) Ye, R.-R.; Tan, C.-P.; He, L.; Chen,
M.-H.; Ji, L.-N.; Mao, Z.-W. Chem. Commun. 2014, 50, 10945−10948.
(k) Maggioni, D.; Galli, M.; D’Alfonso, L.; Inverso, D.; Dozzi, M. V.;
Sironi, L.; Iannacone, M.; Collini, M.; Ferruti, P.; Ranucci, E.;
D’Alfonso, G. Inorg. Chem. 2015, 54, 544−553. (l) Colombo, A.;
Dragonetti, C.; Roberto, D.; Valore, A.; Ferrante, C.; Fortunati, I.;
(17) (a) Aoki, S.; Sakurama, K.; Matsuo, N.; Yamada, Y.; Takasawa,
R.; Tanuma, S.-I.; Shiro, M.; Takeda, K.; Kimura, E. Chem. - Eur. J.
2006, 12, 9066−9080. (b) Ohshima, R.; Kitamura, M.; Shiro, M.;
Morita, A.; Ikekita, M.; Kimura, E.; Aoki, S. Inorg. Chem. 2010, 49,
888−899. (c) Aoki, S.; Sakurama, K.; Ohshima, R.; Matsuo, N.;
Yamada, Y.; Takasawa, R.; Tanuma, S.-I.; Takeda, K.; Kimura, E. Inorg.
Chem. 2008, 47, 2747−2754. (d) Hanaya, K.; Suetsugu, M.; Saijo, S.;
Yamato, I.; Aoki, S. JBIC, J. Biol. Inorg. Chem. 2012, 17, 517−529.
(e) Ariyasu, S.; Mizuseda, Y.; Hanaya, K.; Aoki, S. Chem. Pharm. Bull.
2014, 62, 642−648. (f) Hanaya, K.; Yoshioka, S.; Ariyasu, S.; Aoki, S.;
Shoji, M.; Sugai, T. Bioorg. Med. Chem. Lett. 2016, 26, 545−550.
(g) Ariyasu, S.; Sawa, A.; Morita, A.; Hanaya, K.; Hoshi, M.;
Takahashi, I.; Wang, B.; Aoki, S. Bioorg. Med. Chem. 2014, 22, 3891−
3905. (h) Morita, A.; Ariyasu, S.; Wang, B.; Asanuma, T.; Onoda, T.;
N
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Sawa, A.; Tanaka, K.; Takahashi, I.; Togami, S.; Nenoi, M.; Inaba, T.;
Aoki, S. Biochem. Biophys. Res. Commun. 2014, 450, 1498−1504.
(18) Kageyama, Y.; Ohshima, R.; Sakurama, K.; Fujiwara, Y.;
Tanimoto, Y.; Yamada, Y.; Aoki, S. Chem. Pharm. Bull. 2009, 57,
1257−1266.
(19) (a) Sprouse, S.; King, K. A.; Spellane, P. J.; Watts, R. J. J. Am.
Chem. Soc. 1984, 106, 6647−6653. (b) Agarwal, N.; Nayak, P. K.
Tetrahedron Lett. 2008, 49, 2710−2713. (c) Yang, C. H.; Beltran, J.;
Lemaur, V.; Cornil, J.; Hartmann, D.; Sarfert, W.; Frohlich, R.;
Bizzarri, C.; De Cola, L. Inorg. Chem. 2010, 49, 9891−9901.
(20) Lamansky, S.; Djurovich, P.; Murphy, D.; Abdel-Razzaq, F.;
Kwong, R.; Tsyba, I.; Bortz, M.; Mui, B.; Bau, R.; Thompson, M. E.
Inorg. Chem. 2001, 40, 1704−1711.
1987, 109, 1589−1590. (h) Garces, F. O.; King, K. A.; Watts, R. J.
Inorg. Chem. 1988, 27, 3464−3471. (i) Wilde, A. P.; King, K. A.; Watts,
R. J. J. Phys. Chem. 1991, 95, 629−634.
(32) Rouffet, M.; de Oliveira, C. A. F.; Udi, Y.; Agrawal, A.; Sagi, I.;
McCammon, J. A.; Cohen, S. M. J. Am. Chem. Soc. 2010, 132, 8232−
8233.
(33) Smart & SAINT Software Reference Manuals, Version 6.45;
Bruker Analytical X-ray Systems, Inc: Madison, WI, 2003.
(34) G.M. Sheldrick, SADABS, Software for Empirical Absorption
Correction, Ver.2.05; University of Gottingen: Germany, 2002.
̈
(35) XPREP, 5.1 ed.; Siemens Industrial Automation Inc: Madison,
WI, 1995.
(36) G.M. Sheldrick, SHELXL97, Program for Crystal Structure
Refinement; University of Gottingen: Germany, 2008.
̈
(21) (a) Nazeeruddin, Md. K.; Humphry-Baker, R.; Berner, D.;
Rivier, S.; Zuppiroli, L.; Graetzel, M. J. Am. Chem. Soc. 2003, 125,
8790−8797. (b) Tamayo, A. B.; Garon, S.; Sajoto, T.; Djurovich, P. I.;
Tsyba, I. M.; Bau, R.; Thompson, M. E. Inorg. Chem. 2005, 44, 8723−
8732.
(22) Okada, S.; Okinaka, K.; Iwawaki, H.; Furugori, M.; Hashimoto,
M.; Mukaide, T.; Kamatani, J.; Igawa, S.; Tsuboyama, A.; Takiguchi,
T.; Ueno, K. Dalton Trans. 2005, 9, 1583−1590.
(23) The emission spectra of 19 were measured in degassed DMSO
solution at different temperatures (278 to 323 K) and shown in Figure
S5 in Supporting Information, showing identical emission spectra.
(24) Mitsumori, T.; Campos, L. S.; Garcia-garibay, M. A.; Wudl, F.;
Sato, H.; Sato, Y. J. Mater. Chem. 2009, 19, 5826−5836.
(25) Henwood, A. F.; Evariste, S.; Slawin, A. M. Z.; Zysman-Colman,
E. Faraday Discuss. 2014, 174, 165−182.
(26) (a) Schwaebel, T.; Menning, S.; Bunz, U. H. F. Chem. Sci. 2014,
5, 1422−1428. (b) Schwaebel, T.; Trapp, O.; Bunz, U. H. F. Chem. Sci.
2013, 4, 273−281.
(27) (a) Berns, R. S.; Motta, R. J.; Gorzynski, M. E. CRT
Colorimetry: Part-1 Theory and Practice, Part-2 Metrology Color
Res. Appl., 1993, 18.29910.1002/col.5080180504 (b) Brainard, D. H.
Color Res. Appl. 1989, 14, 23−34. (c) http://colormine.org/convert/
rgb-to-yxy.
(28) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci,
B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H.
P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.;
Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima,
T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.;
Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin,
K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.;
Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega,
N.; Millam, M. J.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.;
Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.;
Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.;
Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.;
̈
Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.;
Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09,
Revision D.01; Gaussian, Inc: Wallingford, CT, 2009.
(29) (a) You, Y.; Park, S. Y. J. Am. Chem. Soc. 2005, 127, 12438−
12439. (b) You, Y.; Kim, K. S.; Ahn, T. K.; Kim, D.; Park, S. Y. J. Phys.
Chem. C 2007, 111, 4052−4060.
(30) Dumur, F.; Lepeltier, M.; Siboni, H. Z.; Gigmes, D.; Aziz, H.
Synth. Met. 2014, 198, 131−136.
(31) The mechanistic studies of dual-emissive transition metal
complexes have been reported, see: (a) Blakley, R. L.; DeArmond, M.
K. J. Am. Chem. Soc. 1987, 109, 4895−4901. (b) Suzuki, T.;
Kuchiyama, T.; Kishi, S.; Takagi, H. D.; Kato, M. Inorg. Chem. 2003,
42, 785−795. (c) Song, L.-Q.; Feng, J.; Wang, X.-S.; Yu, J.-H.; Hou, Y.-
J.; Xie, P.-H.; Zhang, B.-W.; Xiang, J.-F.; Ai, X.-C.; Zhang, J.-P. Inorg.
Chem. 2003, 42, 3393−3395. (d) Glazer, E. C.; Magde, D.; Tor, Y. J.
Am. Chem. Soc. 2005, 127, 4190−4192. (e) Glazer, E. C.; Magde, D.;
Tor, Y. J. Am. Chem. Soc. 2007, 129, 8544−8551. (f) Sen, R.; Koner,
S.; Bhattacharjee, A.; Kusz, J.; Miyashita, Y.; Okamoto, K.-I. Dalton
Trans. 2011, 40, 6952−6960. Dual emission from Ir(III) complexes at
77 K temperature, see (g) King, K. A.; Watts, R. J. J. Am. Chem. Soc.
O
DOI: 10.1021/acs.inorgchem.5b02872
Inorg. Chem. XXXX, XXX, XXX−XXX