Synthesis, characterization and optical properties of novel Ir(III) complexes bearing N-heterocycle substituents

Article abstract of DOI:10.1016/j.jorganchem.2018.11.031

A series of cationic heteroleptic Ir(III) complexes with different N-heterocycle groups (N-phenothiazinyl, N-indolyl, N-carbazolyl, 3,6-di-tert-butyl-N-carbazolyl) were synthesized and characterized. The photophysical properties of these complexes were systematically investigated. All complexes exhibit strong ¹π-π^? absorption bands in the UV region and broad ¹MLCT absorption bands in the visible region. In addition, these complexes exhibit weak absorption after 500 nm, which could be attributed to ³π,π^?/³CT transition. All complexes exhibit broad and structureless emission bands from 568 nm to 627 nm at room temperature, which are originated from ³MLCT/³LLCT excited states. The electron donating substituents attached on the 2-phenylpyridine ligands cause a pronounced red-shift of the emission band. Except 1d, all complexes show strong triplet transient absorptions from UV to visible region, which were assigned to the ³MLCT/³π,π^? excited state. In addition, complexes 1a-1c all exhibit reverse saturable absorption (RSA) at 532 nm, which follows the trend of 1a>1b > 1c. The photophysical properties of these Ir(III) complexes can be influenced drastically by the substituents on 2-phenylpyridine ligands, which would be useful for rational design of optical functional materials.

Full text of DOI:10.1016/j.jorganchem.2018.11.031

Accepted Manuscript
Synthesis, characterization and optical properties of novel Ir(III) complexes bearing N-
heterocycle substituents
Meng Tang, Senqiang Zhu, Rui Liu, Jia Wang, Zheng Zhang, Hongjun Zhu
PII:
S0022-328X(18)30826-X
DOI:
https://doi.org/10.1016/j.jorganchem.2018.11.031
JOM 20651
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 18 September 2018
Revised Date: 9 November 2018
Accepted Date: 24 November 2018
Please cite this article as: M. Tang, S. Zhu, R. Liu, J. Wang, Z. Zhang, H. Zhu, Synthesis,
characterization and optical properties of novel Ir(III) complexes bearing N-heterocycle substituents,
Journal of Organometallic Chemistry (2018), doi: https://doi.org/10.1016/j.jorganchem.2018.11.031.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Synthesis, characterization and optical properties of novel
Ir(III) complexes bearing N-heterocycle substituents
Meng Tang, Senqiang Zhu, Rui Liu*, Jia Wang, Zheng Zhang, Hongjun Zhu*
Department of Applied Chemistry, College of Chemistry and Molecular Engineering,
Nanjing Tech University, Nanjing 211816, China.
ABSTRACT: A series of cationic heteroleptic Ir(III) complexes with different
N-heterocycle
,6-di-tert-butyl-N-carbazolyl) were synthesized and characterized. The photophysical
properties of these complexes were systematically investigated. All complexes exhibit
groups
(N-phenothiazinyl,
N-indolyl,
N-carbazolyl,
3
1
*
1
strong π-π absorption bands in the UV region and broad MLCT absorption bands in
the visible region. In addition, these complexes exhibit weak absorption after 500 nm,
3
* 3
which could be attributed to π,π / CT transition. All complexes exhibit broad and
structureless emission bands from 568 nm to 627 nm at room temperature, which are
3
3
originated from MLCT/ LLCT excited states. The electron donating substituents
attached on the 2-phenylpyridine ligands cause a pronounced red-shift of the emission
band. Except 1d, all complexes show strong triplet transient absorptions from UV to
3
3
*
visible region, which were assigned to the MLCT/ π,π excited state. In addition,
complexes 1a-1c all exhibit reverse saturable absorption (RSA) at 532 nm, which
follows the trend of 1a>1b>1c. The photophysical properties of these Ir(III)
complexes can be influenced drastically by the substituents on 2-phenylpyridine
ligands, which would be useful for rational design of optical functional materials.
Keywords: Ir(III) complex; N-heterocycle; Synthesis; Photophysics property;
Nonlinear absorption.

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Cyclometalated Ir(III) complexes have attracted extensive interest in the past
decade, due to the strong spin–orbit coupling induced by the Ir(III) ion, which gives
rise to efficient intersystem crossing and high phosphorescence quantum efficiencies.
This unique feature makes the Ir(III) complexes promising candidates for applications
1
-4
in organic light-emitting devices (OLEDs) , organic light-emitting electrochemical
5
6-7
8-10
11-12
transistor , low-power upconversion , photocatalysts
and nonlinear optics
.
These applications are intrinsically based on their rich photochemical and
photophysical properties. In addition, their photophysical properties can be modulated
by structural modification of the ligands to meet the requirements for different
applications.
Among these Ir(III) complexes, cationic heteroleptic Ir(III) complexes are more
appealing because the ground-state and excited-state properties of these complexes
can be readily tuned by modification of either the diimine (N^N) ligand or the
1
3-17
cyclometalating 2-arylpyridine (C^N) ligands
. For example, the research
conducted by Sun group demonstrated that π-conjugations on the N^N ligands could
significantly change the excited-state absorption characteristics of the Ir(III)
11
complexes, and thus strongly impact their photophysical properties . In addition,
,10-phenanthroline has been amply confirmed that its rigid and conjugated structure
1
makes the density of the electron cloud of the nitrogen atom on the aromatic ring
stronger, which is favorable for the efficient transfer of electron energy between atoms
and the coordination with metal center. Furthermore, Thompson group reported Ir(III)
complexes bearing electron donors and acceptors on monoanionic cyclometalating
1
8
ligands , which indicate that cyclometalated ligands are a key factor in the physical
properties of Ir(III) complexes due to the effect of functional substituents on the
ligands. Therefore, a strategy for achieving superior nonlinear optical properties could
be proposed by the introduction of different substituents.
Furthermore, the investigation on the nonlinear optical properties of Ir(III)
complexes by modifying cyclometalating C^N ligands is still limited. We envision
that by incorporating N-aryl chromophores (N-arylamines) with different
electron-donating abilities on 2-arylpyridine ligands, ground state absorption and

ACCEPTED MANUSCRIPT
excited state absorption of these complexes will be significantly tuned, hence, their
excited state absorption region could be extended accordingly.
In this work, a series of cationic heteroleptic Ir(III) complexes with different
arylamino-substituents on 2-phenylpyridine ligands, structurally, N-phenothiazinyl,
N-indolyl, N-carbazolyl, 3,6-di-tert-butyl-N-carbazolyl groups were synthesized
(
Scheme 1). These complexes based on 1,10-phenanthroline ligand as main ligand
N^N ligand) and modified 2-phenylpyridine as ancillary ligand (C^N ligand). The
(
structural characterization and photophysical properties of these complexes were
systematically investigated with the aim of understanding the structure-property
correlations and developing novel functional materials. The synthetic details are
provided in Supplementary Information.
Scheme 1. Synthetic routes for complexes 1a–1d.
The UV−vis absorption characteristics of complexes 1a−1d were studied in
−
6
−4
−1
CH Cl at different concentrations (5×10 to 1×10 mol·L ). The absorption
2
2
obeyed the Beer’s law in the studied concentration range, suggesting the absence of
ground-state aggregation in this concentration range. The UV–vis absorption spectra

ACCEPTED MANUSCRIPT
of complexes 1a-1d in CH Cl solution is presented in Fig.1. The band maxima and
2
2
molar extinction coefficients for each complex are summarized in Table 1. The
spectra of the complexes 1a-1d consist of intense absorption bands below 300 nm,
medium absorption bands between 300 ~ 500 nm, and broad weak tails above 500 nm.
In comparison to their respective ligands (2a-2d, Fig. S1), the strong absorption bands
1
of the Ir(III) complexes above 300 nm can be assigned to ligand-based π,π*
transitions (Fig. 1), which are also in line with the other transition organometallic
1
9-21
compounds reported previously
. The less intense bands in the range of 300 ~ 500
1
1
nm for complexes have a mixed MLCT and LLCT character in view of their
relatively large extinction coefficients. A close examination of the UV-vis absorption
spectra of these complexes revealed a very weak tail beyond 500 nm for complexes
2
2
1
a-1d. As reported for other Ir(III) complexes , these bands are attributed to the
3
* 3
S -Tn absorption via the spin-forbidden π,π / CT transition. It is worth noting that
0
the N-heterocycle substituents complexes exhibit red-shifted absorption of the
charge-transfer absorption bands compared to those of their analogues without the
2
3-24
N-heterocycle substituents
.
5
4
3
2
1
x10
0
0
0
0
.06
.04
.02
.00
1a
1b
1c
1d
5
x10
5
x10
5
00
600
700
800
Wavelength (nm)
5
x10
ε
ε
0
300 400 500 600 700 800
Wavelength(nm)
-5
Fig. 1. UV–vis absorption spectra of 1a-1d in CH Cl (1×10 mol/L). The inset shows the
2
2
expanded spectra in the spectral region 400–800 nm.
Table 1. Photophysical parameters of complexes 1a-1d
.
a
5
−1
−1
b
d
Complex
λabs /nm (ε/10 L·mol ·cm )
λem /nm (τ /µs, Φ ) λT1-Tn/nm (τ /µs)
em em
TA

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1a
1b
1c
270 (2.85), 322 (0.77), 422 (0.117)
570 (3.00, 0.36)
540 (3.02)
525 (0.11)
266 (2.62), 348 (0.49), 436 (0.098) 616 (0.12, 0.24)
266 (3.49), 426 (0.179)
604 (0.06, 0.47)
520 (0.05)
c
c
1
d
264 (3.27), 342 (0.58), 436(0.105)
627 ( , 0.22)
a
Electronic absorption band maxima in CH Cl at R.T.
2
2
b
c
d
-5
Recorded in 1×10 mol/L CH Cl solution at R.T.
2
2
Too weak to be measured.
Nanosecond TA band maxima, triplet extinction coefficients and triplet excited-state lifetimes in
toluene at room temperature.
The normalized room-temperature emission spectra of complexes 1a-1d in CH Cl
2
2
are shown in Fig. 2 and the emission data of 1a–1d are summarized in Table 1. Upon
1
excitation at the corresponding MLCT band, a broad and structureless emission band
appears from 568 nm to 627 nm for 1a-1d. Considering the significant stokes shifts
and sensitivity to oxygen quenching (Fig. S2), the emitting state of these complexes
should be attributed to a triplet excited state (T excited state). In comparison to their
1
respective ligands (2a-2d, Fig. S3), these complexes show broad and unstructured
emission bands and point to a higher MLCT character and intraligand (IL) character
in the excited state. Furthermore, the observed difference in emission should be
attributed to the different natures of the substituents attached on the terminal
N-heterocyclic unit, the N-heterocycle substituents complexes exhibit red-shifted of
the charge-transfer emission bands compared to those of their analogues without the
23-24
N-heterocycle substituents
substituents. Compared to 1c, complex 1d bearing stronger electron-donating
,6-di-tert-butyl-N-carbazolyl groups shows pronounced red-shift emission with
, especially the electron-donating ability of the
3
structured feature. However, the emission quantum yield of 1d decreases significantly
by introducing tert-butyl groups on carbazole units, we ascribe the drastically reduced
emission of 1d to the enhanced intramolecular charge-transfer state, particularly the
3
LLCT state caused by the electron-donating tert-butyl-N-carbazolyl group in the
Ir(III) complex.

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1.0
0.8
0.6
0.4
0.2
0.0
1
1
1
1
a
b
c
d
5
50 600 650 700 750 800
Wavelength (nm)
-5
Fig.2. Normalized emission spectra of 1a-1d in CH Cl (1×10 mol/L).
2
2
The photoluminescence of 1a-1d in different solvents was investigated to further
understand the nature of the emission, the solvent-dependency emission spectra of
1
a-1d are manifested in Fig. 3, and the emission quantum yields of these four
complexes in different solvents are summarized in Table 2. A negative solvatochromic
effect is observed for 1a and 1b. However, a slight positive solvatochromic effect is
observed for 1d, while minor solvatochromic effect is observed for 1c. These
indicating that the emitting states for these complexes are configurationally mixed
excited states or the emitting state changes in different solvents. Considering the
structureless feature of the emission spectra, the emitting states for 1a-1d are
3
3
predominantly MLCT/ LLCT in nature. In addition, in a non-coordinating solvent
like CH Cl , higher quantum yields are observed for these complexes in comparison
2
2
to coordinating solvent like CH CN. This provides evidence for the involvement of
3
3
the MLCT character in the emitting state of these complexes. The solvent induced
quenching by coordinating solvents is a common feature for transition-metal
3
complexes with a MLCT emitting state.

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1
.0 1a
.8
.6
.4
.2
.0
Toluene
THF
1.0
0.8
0.6
0.4
0.2
0.0
Toluene
THF
1b
0
CH Cl
CH Cl
2
2
2
2
CH CN
3
CH CN
3
0
0
0
0
550
600
650
700
750
550 600 650 700 750 800
Wavelength (nm)
Wavelength (nm)
1
.0 1c
.8
.6
.4
.2
.0
Toluene
THF
1.0 1d
0.8
Toluene
THF
CH Cl
2 2
0
CH Cl
2
2
CH CN
3
CH CN
3
0
0.6
0
0.4
0
0.2
0
0.0
550
600
650
700
750
550 600 650 700 750 800
Wavelength (nm)
Wavelength (nm)
-5
Fig.3. Emission spectra of 1a-1d (1×10 mol/L) in different solutions.
Table 2. Emission energy and quantum yields of 1a–1d in different solvents
a
λ /nm (Φ )
em
em
Toluene
THF
CH Cl
CH CN
2
2
3
1
1
a
615 (0.30)
612 (0.22)
606 (0.37)
595 (0.34)
603 (0.37)
570 (0.36)
616 (0.24)
627 (0.47)
558 (0.33)
617 (0.37)
622 (0.44)
b
1
c
625 (0.41)
615 (0.27)
1
d
612 (0.35)
604 (0.22)
609 (0.37)
a
Degassed aqueous solution of [Ru(bpy) ]Cl (Φ = 0.042, excited at 436 nm) was used as the
3
2
em
reference for the emission quantum yield measurement.
In order to understand the triplet excited-state properties of 1a–1d, the triplet
transient absorption (TA) of these complexes in toluene and monitoring the decay
characteristics. The time-resolved triplet TA spectra of 1a, 1b, 1c recorded upon
excitation at 355 nm at room temperature in deaerated toluene solutions are shown in
Fig. 4. The TA absorption band maxima, the excited-state lifetimes deduced from the
decay of the TA, which are listed in Table 1. It is obvious that the TA spectral features
of Ir(III) complexes 1a, 1b, 1c exhibit broad positive absorption bands from 300 nm
to 550 nm. The TA spectrum of 1a is drastically different from other complexes, it

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exhibits broad positive absorption bands from 300 nm to 800 nm, which was
3
3
*
tentatively assigned to the MLCT/ π,π excited state. Meanwhile, the TA spectra of
b and 1c show bleaching bands from 600 nm to 700 nm. The triplet excited state
1
3
3
giving rise to the observed TA for 1b and 1c could be assigned to the MLCT/ LLCT
2
5-27
excited state. According to the literature
, it is not surprised that the TA spectra of
1
d was unable to be measured, because the shorter excited state lifetime as indicated
by the emission lifetime. These spectral information obtained from TA spectra of the
complexes helps us to understand the excited state properties and to predict the
spectral region where reverse saturable absorption occurs, which could be useful for
nonlinear optics.
0
0
0
0
.03
.02
.01
.00
0.01
1
a
1b
0.00
0
-0.01
0
1
.4
µ
µ
µ
µ
s
s
s
s
40 ns
-0.01
2.8
80 ns
120 ns
160 ns
4
.2
5.6
-0.02
-0.02
400
500
600
700
800
400
500
600
700
800
Wavelength (nm)
Wavelength (nm)
0.02
1
c
0
.01
.00
0.01
0.02
0.03
0.04
0
-
0
-
4
8
1
1
0 ns
0 ns
20 ns
60 ns
-
-
400
500
600
700
800
Wavelength (nm)
Fig. 4. The time-resolved triplet transient difference absorption spectra of 1a-1c in toluene
solution.
In order to study non-linear optical behaviors properties of the complexes,
nonlinear transmission measurements were carried out in toluene solutions for all
complexes at 532 nm using 4.1 ns laser pulses. For easy comparison, the linear
transmission of all sample solutions was adjusted to 80% in a 2 mm cuvette at 532 nm
to ensure that the same numbers of molecules are populated to the excited states. In
such a case, the degree of reverse saturable absorption (RSA) will be determined by

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the excited-state absorption. The transmission vs. incident fluence curves for these
complexes are presented in Fig. 5. Three complexes exhibit strong RSA properties at
5
32 nm for ns laser pulses, following the order of 1a > 1b > 1c. In addition, compared
+
24
with the [Ir(ppy) (phen)] without N-heterocycle substituents , N-heterocycle
2
substituents on ancillary ligands influence the non-linear optical properties of Ir(III)
complexes significantly.
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
1
1
1
a
b
c
0.0
0.5
1.0
1.5
2.0
2
Incident Fluence (J/cm )
Fig. 5. Output energy density vs incident energy density of complexes 1a-1c in toluene for 4.1 ns
laser pulses at 532 nm. The linear transmission for all samples was adjusted to 80% in a 2 mm
cuvette at 532 nm.
In summary, four Ir(III) complexes were synthesized and their photophysical
properties were systematically investigated. All complexes exhibit strong absorption
bands in the UV region, and broad structureless bands in visible region, which can be
1
1
assigned as the ligand-based π,π* transitions and MLCT transitions, respectively. In
addition, all complexes exhibit weak absorption after 500 nm, which come from
3
*
3
3
mixed π-π , LLCT and MLCT. Our studies reveal that electron-donating
substituents on 2-phenylpyridine ligands cause a pronounced red-shift of emission
bands. All the complexes exhibit broad absorption bands in their triplet transient
difference absorption spectra, which are attributed to the ancillary ligand localized
triplet excited states. The complexes 1a, 1b, 1c exhibit broad absorption bands in their

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triplet transient difference absorption spectra, which are also influenced by these
attached substituents. These complexes exhibit strong RSA properties at 532 nm for
ns laser pulses, which was significantly influenced by the N-heterocycle substituents
on ancillary ligands. These studies indicate that the photophysical properties of these
Ir(III) complexs can be tuned drastically by the different aryl substituents, which not
only builds a foundation in both experiment and theory of the further study on the
synthesis and photophysical properties of cyclometalated iridium complexes, but also
provides experiment and theory reference with the cyclometalated Ir(III) complexes
for the applications in nonlinear optics
.
Acknowledgements
We greatly acknowledge the financial support in part by National Natural
Science Foundation of China (21602106), Natural Science Foundation of Jiangsu
Province-Outstanding Youth Foundation (BK20170104), “Six Talent Peaks Project”
of Jiangsu Province (XCL-037), Strategic Pioneer Program on Space Science,
Chinese Academy of Sciences (XDA15013100, XDA15013101) and Postgraduate
Research & Practice Innovation Program of Jiangsu Province (KYCX17_0932).
References
[
1] A. Tsuboyama, H. Iwawaki, M. Furugori, T. Mukaide, J. Kamatani, S. Igawa, T.
Moriyama, S. Miura, T. Takiguchi, S. Okada, M. Hoshino, K. Ueno, Homoleptic
cyclometalated iridium complexes with highly efficient red phosphorescence and
application to organic light-emitting diode, J. Am. Chem. Soc. 125 (2003)
1
2971-12979.
[
2] S.T. Parker, J.D. Slinker, M.S. Lowry, M.P. Cox, S. Bernhard, G.G. Malliaras,
Improved turn-on times of iridium electroluminescent devices by use of ionic liquids,
Chem. Mater. 17 (2005) 3187-3190.
[
3] B.S. Du, C.H. Lin, Y. Chi, J.Y. Hung, M.W. Chung, T.Y. Lin, G.H. Lee, K.T. Wong,
P.T. Chou, W.Y. Hung, H.C. Chiu, Diphenyl(1-naphthyl)phosphine ancillary for
assembling of red and orange-emitting Ir(III) based phosphors; strategic synthesis,

ACCEPTED MANUSCRIPT
photophysics, and organic light-emitting diode fabrication, Inorg. Chem. 49 (2010)
8
713-8723.
[
4] W.Y. Wong, G.J. Zhou, X.M. Yu, H.S. Kwok, Z.Y. Lin, Efficient organic
light-emitting diodes based on sublimable charged iridium phosphorescent emitters,
Adv. Funct. Mater. 17 (2007) 315-323.
[
5] Y. Zhou, S.T. Han, G.J. Zhou, W.Y. Wong, V.A.L. Roy, Ambipolar organic
light-emitting electrochemical transistor based on a heteroleptic charged iridium(III)
complex, Appl. Phys. Lett. 102 (2013) 083301.
[
6] W. Zhao, F.N. Castellano, Upconverted emission from pyrene and
di-tert-butylpyrene using Ir(ppy) as triplet sensitizer, J. Phys. Chem. A 110 (2006)
3
11440-11445.
[
7] A.A. Rachford, R. Ziessel, T. Bura, P. Retailleau, F.N. Castellano, Boron
+
dipyrromethene (bodipy) phosphorescence revealed in [Ir(ppy) (bpy-C≡C-Bodipy)] ,
2
Inorg. Chem. 49 (2010) 3730-3736
[
8] K.A. Belmore, R.A. Vanderpool, J.C. Tsai, M.A. Khan, K.M. Nicholas,
Transition-metal-mediated photochemical disproportionation of carbon dioxide, J. Am.
Chem. Soc. 110 (1988) 2004-2005.
[
9] B. Matt, J. Moussa, L.M. Chamoreau, C. Afonso, A. Proust, H. Amouri, G. Izzet,
Elegant approach to the synthesis of a unique heteroleptic cyclometalated
iridium(III)-polyoxometalate conjugate, Organometallics. 31 (2012) 35-38.
[
10] X. Zhou, J. Yang, C. Li, Theoretical study of structure, stability, and the
hydrolysis reactions of small iridium oxide nanoclusters, J. Phys. Chem. A 116 (2012)
985-9995.
9
[
11] L. Liu, N. Dandu, J. Chen, Y. Li, Z. Li, S. Liu, C. Wang, S. Kilina, B. Kohler,
∧
W.F. Sun, Influence of different diimine (N N) ligands on the photophysics and
reverse saturable absorption of heteroleptic cationic iridium(III) complexes bearing
cyclometalating 2-{3-[7-(Benzothiazol-2-yl)fluoren-2-yl]phenyl}pyridine (C^N)
ligands, J. Phys. Chem. C 118 (2014) 23233-23246.
[
12] L. Liu, N. Dandu, C. McCleese, Y. Li, T. Lu, H. Li, D. Yost, C. Wang, S. Kilina,
C. Burda, W.F. Sun, Influence of a naphthaldiimide substituent at the diimine ligand

ACCEPTED MANUSCRIPT
on the photophysics and reverse saturable absorption of PtII diimine complexes and
cationic IrIII complexes, Eur. J. Inorg. Chem. 2015 (2015) 5241-5253.
[
13] F. Neve, M. La Deda, A. Crispini, A. Bellusci, F. Puntoriero, S. Campagna,
Cationic cyclometalated iridium luminophores: photophysical, redox, and structural
characterization, 23 (2004) 5856-5863.
[
14] Q. Zhao, S.J. Liu, M. Shi, C.M. Wang, M.G. Yu, L. Li, F.Y. Li, T. Yi, C.H. Huang,
Series of new cationic iridium(III) complexes with tunable emission wavelength and
excited state properties:ꢀ structures, theoretical calculations, and photophysical and
electrochemical properties, Inorg. Chem. 45 (2006) 6152-6160.
[
15] S. Ladouceur, D. Fortin, E. Zysman-Colman, Role of substitution on the
*
*
photophysical properties of 5,5′-Diaryl-2,2′-bipyridine (bpy ) in [Ir(ppy) (bpy )]PF
2
6
complexes: a combined experimental and theoretical study, Inorg. Chem. 49 (2010)
625-5641.
16] R.D. Costa, F. Monti, G. Accorsi, A. Barbieri, H.J. Bolink, E. Ortí, N. Armaroli,
5
[
Photophysical properties of charged cyclometalated Ir(III) complexes: a joint
theoretical and experimental study, Inorg. Chem. 50 (2011) 7229-7238.
[
17] S. Ladouceur, D. Fortin, E. Zysman-Colman, Enhanced luminescent iridium (III)
complexes bearing aryltriazole cyclometallated ligands, Inorg. Chem. 50 (2011)
1514-11526.
18] A.B. Tamayo, B.D. Alleyne, P.I. Djurovich, S. Lamansky, I. Tsyba, N.N. Ho, R.
1
[
Bau, M.E. Thompson, Synthesis and characterization of facial and meridional
tris-cyclometalated iridium(III) complexes, J. Am. Chem. Soc. 125 (2003) 7377-7387.
[
19] I.E. Pomestchenko, F.N. Castellano, Solvent switching between charge transfer
and intraligand excited states in a multichromophoric platinum(II) complex, J. Phys.
Chem. A 108 (2004) 3485–3492.
[
20] K. Haskins-Glusac, I. Ghiviriga, K.A. Abboud, K.S. Schanze, Photophysics and
photochemistry of stilbene-containing platinum acetylides, J. Phys. Chem. B 108
(2004) 4969–4978.
[
21] X.S. Li, Y. Liu, J. Luo, Z.Y. Zhang, D.Y. Shi, Q. Chen, Y.F. Wang, J. He, J.M. Li,
G.T. Lei, W.G. Zhu, Synthesis and optoelectronic properties of a heterobimetallic

ACCEPTED MANUSCRIPT
Pt(II)–Ir(III) complex used as a single-component emitter in white PLEDs, Dalton
Trans. 41 (2012) 2972–2978.
[
22] C. Wang, L. Lystrom, H. Yin, M. Hetu, S. Kilina, S.A. McFarland, W.F. Sun,
Increasing the triplet lifetime and extending the ground-state absorption of
biscyclometalated Ir(III) complexes for reverse saturable absorption and
photodynamic therapy applications, Dalton Trans. 45 (2016) 16366-16378.
[
23] M.S. Lowry, W.R. Hudson, R.A. Pascal, Accelerated Luminophore Discovery
through Combinatorial Synthesis, J. Am. Chem. Soc.126 (2004) 14129-14135.
24] Y.H. Li, R. Liu, Z.J. Li, S. Kilina, W.F. Sun, Effects of extended π-conjugation in
[
phenanthroline (N^N) and phenylpyridine (C^N) ligands on the photophysics and
reverse saturable absorption of cationic heteroleptic iridium(III) complexes, J. Phys.
Chem. C 118 (2014) 6372−6384.
[
25] F.Q. Guo, W.F. Sun, Y. Liu, K. Schanze, Synthesis, photophysics, and optical
limiting of Pt(II) 4′-tolylterpyridyl arylacetylide complexes, Inorg. Chem. 44 (2005)
055–4065.
26] P. Shao, Y.J. Li, W.F. Sun, Cyclometalated Pt(II) complex with strong and
broadband nonlinear optical response, J. Phys. Chem. A 112 (2008) 1172–1179.
27] J. Yi, B.G. Zhang, P. Shao, Y.J. Li,W.F. Sun, Synthesis and photophysics of Pt(II)
-phenyl-4-(9,9-dihexylfluoren-2-yl)-2,2′-bipyridine complexes with phenothiazinyl
acetylide ligand, J. Phys. Chem. A 114 (2010) 7055–7062.
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Highlights
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©
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Four cationic Ir complexes with different N-heterocycle groups were synthesized.
The photophysical properties of these Ir complexes were investigated.
These complexes could be useful for rational design of nonlinear optical
materials.