Heteroleptic iridium(III) complex with N-heterocyclic carbene ligand: Synthesis, photophysics, theoretical calculations and electrochemiluminescence

Article abstract of DOI:10.1016/j.jorganchem.2017.07.017

A novel C_(carbene)?O bidentate ancillary ligand has been designed and synthesized through an imidazolium bromide with carboxylic acid as a N-heterocyclic carbene (NHC) precursor, and further successfully been coordinated to iridium center for the first time in this work. Accordingly, a NHC-based iridium(III) complex has been synthesized and characterized by chemical structural (NMR, mass, UPLC purity, single crystal structure), photophysical, theoretical calculation, electrochemical and electrochemiluminescent (ECL) properties. Most importantly, five alkyl amines have been selected as co-reactants for ECL generation of this novel ECL luminophores and the relationships between ECL intensity and the co-reactant have been investigate by experimental results and theoretical calculations, which would be very important to exploit novel excellent co-reactants for the emerging iridium-based ECL luminophores in the future.

Full text of DOI:10.1016/j.jorganchem.2017.07.017

Accepted Manuscript
Heteroleptic Iridium(III) complex with N-heterocyclic carbene ligand: Synthesis,
photophysics, theoretical calculations and electrochemiluminescene
Yuyang Zhou, Lingyan Kong, Kai Xie, Chengbao Liu
PII:
S0022-328X(17)30446-1
10.1016/j.jorganchem.2017.07.017
JOM 20031
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 17 May 2017
Revised Date: 10 July 2017
Accepted Date: 12 July 2017
Please cite this article as: Y. Zhou, L. Kong, K. Xie, C. Liu, Heteroleptic Iridium(III) complex
with N-heterocyclic carbene ligand: Synthesis, photophysics, theoretical calculations and
electrochemiluminescene, Journal of Organometallic Chemistry (2017), doi: 10.1016/
j.jorganchem.2017.07.017.
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ACCEPTED MANUSCRIPT

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Heteroleptic Iridium(III) Complex with N-heterocyclic Carbene
Ligand: Synthesis, Photophysics, Theoretical Calculations and
Electrochemiluminescene
a,*
a
a
a
Yuyang Zhou, Lingyan Kong, Kai Xie, Chengbao Liu
a
School of Chemistry, Biology and Material Engineering, Jiangsu Key Laboratory of
Environmental Functional Materials, Suzhou University of Science and Technology, Suzhou,
Jiangsu, 215009, China. E-mail: zhouyuyang@mail.usts.edu.cn
Abstract
A novel C(carbene)^O bidentate ancillary ligand has been designed and synthesized through
an imidazolium bromide with carboxylic acid as a N-heterocylic carbene (NHC) precursor,
and further successfully been coordinated to iridium center for the first time in this work.
Accordingly, a NHC-based iridium(III) complex has been synthesized and characterized by
chemical structural (NMR, mass, UPLC purity, single crystal structure), photophysical,
theoretical calculation, electrochemical and electrochemiluminescent (ECL) properties. Most
importantly, five alkyl amines have been selected as co-reactants for ECL generation of this
novel ECL luminophores and the relationships between ECL intensity and the co-reactant
have been investigate by experimental results and theoretical calculations, which would be
very important to exploit novel excellent co-reactants for the emerging iridium-based ECL
luminophores in the future.
Keywords:
N-heterocyclic
Carbene;
iridium
complex;
electrochemistry;
electrochemiluminescent; co-reactant

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Supplementary material: NMR spectra; UPLC spectra; the oxidative curves of five
co-reactants; cartesian coordinates in xyz format of the optimized geometries of iridium(III)
complex and five co-reactants on the ground state.
Introduction
Since the detailed ECL mechanism of tri-2,2’-bipyridylruthenium(II) [abbreviated as
2
+
Ru(bpy) ] revealed by Bard and co-workers in the early 1970s,[1, 2]
3
electrochemiluminescence (ECL), also named electrogenerated chemiluminescene, has been
developed to be an powerful analytical technique in terms of sensitivity, dynamic
concentration response range.[3, 4] Due to the importance of luminophores in the
luminescence-based analytical techniques, exploiting novel excellent ECL dyes is always the
research hotspot in the ECL-related technologies.[5-7]
Currently, except ruthenium(II) complexes, there has been a large number of
non-ruthenium ECL dyes reported so far, such as europium,[8] rhenium,[9] copper,[10]
osmium,[11] aluminum,[12, 13] terbium,[14] platinum[15] and iridium.[15-24] In the
non-ruthenium system, iridium(III) complexes received much attention[25-30] and are
2
+
identifed as the most competent canditates of the alternatives of Ru(bpy)3 due to their high
quantum efficiencies, tunable emission colors. Our goup[23, 24, 31] and others[32-38] have
focused on exploiting novel excellent ECL dyes comprising iridium(III) complexes.
After the successful isolation of a crystalline and stable carbene by Arduengo and
co-workers in 1991,[39] N-heterocyclic carbene (NHC) derived from the deprotonation of
imidazolium salts has attracted much attentions as coordination ligands in organometallic

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chemistry.[40] Due to NHC’s strong coordination abilities to transition metals, a large number
of NHC-based transition-metal complexes, such as ruthenium,[41] gold,[42, 43] silver,[44]
rhenium,[45] platinum,[46, 47] copper[48] etc., have been designed and synthesized. Beyond
their traditional applications in catalytic chemistry, luminescence and related functional
materials have also become emerging research focuses for NHC-based organometallic
complexes.[49] Since the pioneering work about NHC-based iridium(III) complexes as
dopants of organic light emitting diodes (OLEDs) reported by Sajoto et al,[50] the synthetic
methods[51] and novel applications[52] about luminescent iridium(III) complexes containing
NHC ligands have been gradually revealed. From then on, more and more kinds of NHC
ligands have been designed and incorporated into iridium complexes, which have displayed
excellent properties in related areas, such as OLEDs[53-55] and bio-imaging.[52] However,
as a family of relatively new luminescent complexes with increasing importance, the studies
about ECL properties of the NHC-based iridium complexes are still very rare until now.[56]
Herein, N-methyl-N’-(acetic acid)imidazolium bromide as a a novel NHC precursor has
been designed and successfully synthesized. Furthermore, one NHC-based iridium(III)
complexes with C(carbene)^O bidentate ancillary ligand has also been synthesized through metal
transfer reaction between silver and iridium(III) in this work (as shown in Scheme 1). Beside
the characterization of chemical structure, the photoluminescent and electrochemiluminescent
properties of this novel NHC-based iridium(III) complex have been comprehensively
investigated in this work. Most importantly, the relationship between ECL performance and
co-reactant are also thoroughly investigated based on experimental results and theoretical
calculations in this study, which would be very helpful to develop efficient coreactant assisted

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ECL system for the emerging iridium-based ECL luminophores in the future.
Scheme 1. The synthetic routes of iridium(III) complex used in this work. i: CH CN, reflux, 24
3
hours, N ; ii: Ag O, CH Cl , reflux, 12 hours, N , in dark; iii, 2-ethoxyethanol/H O(v:v=3:1),
2
2
2
2
2
2
reflux, 24 hours, N ; iv: xylenes, K CO , 24 hours, N , in dark.
2
2
3
2
Results and discussions
Synthesis and characterization
Due to the unique nature of carbene, including electronic effect and steric effect,[57] it’s
usually hard to find a general method to synthesize the NHC-based iridium complexes after
reviewing the literatures reported so far.[50, 51, 53, 56, 58, 59] In this work, C^O bidentate
ligand as a novel NHC-based ancillary ligand is coordinated to iridium(III) center and the
corresponding NHC-based iridium(III) complex (abbreviated as Irppyimac in this work) has
been successfully synthesized through two major steps as shown in Scheme 1. The first step
mainly involved the synthesis of two critical intermediates, i.e. iridium(III) dichlorobridged
dimer and silver carbene. For the intermediate of iridium(III) dichlorobridged dimer, the
synthetic method is well-established[60, 61] and there is no need to discuss further. However,
it should be noted the synthesis of Ag carbene. According to Scheme 1, the quaternary
ammonium reaction between 1-methyl-1H-imidazole and 2-bromoacetic acid was employed

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to synthesize the imidazolium bromide as NHC precursor. Subsequently, Ag carbene was
formed by the reaction between this precursor with silver oxide in dichloromethane solution
with nitrogen atomosphere protecting from light.[62] Without purification, Ag carbene was
directly used to react with iridium(III) dichlorobridged dimer and the final NHC-based
iridium(III) complex was generated through metal transfer reaction in base condition as
shown in Scheme 1. The chemical structure of this novel NHC-based iridium complex is
characterized by NMR and mass spectra, the purity is up to 99% according to UPLC spectra
(
Figure S3 in supplementary material). Furthermore, the single crystal structure of this
complex has also been obtained from the mixture solution of methanol and dichloromethane
and shown in Figure 1.
The critical bond lengths and angles of Irppyimac have also been listed in Table 1.
Notably, the bond length between carbene carbon and iridium atom (Ir(1)-C(3) in Table 1 and
Figure 1) is a little longer than that between general carbon (non-carbene) and iridium atom
(
such as Ir(1)-C(18) and Ir(1)-C(7) in Table 1 and Figure 1). According to Figure 1 and Table 1,
two coordinated nitrogen atoms in the main ligands (N(4) and N(3)) are in the trans position
o
and the bond angle of N(4)-Ir(1)-N(3) are nearly to 180 , while the coordinated carbon atoms in
the main ligand (C(18) and C(7)) are in the cis position and the bond angle of C(18)-Ir(1)-C(7) is
o
close to 90 . Furthermore, two bond angles between main ligand and central iridium atom
(
C(18)-Ir(1)-N(4) and C(7)-Ir(1)-N(3) in Table 1 and Figure 1) are nearly identical to each other,
while they are slightly larger than that between NHC-based ancillary ligand and iridium atom
C(3)-Ir(1)-O(1) in Table 1 and Figure 1). According to single crystal structure, the comparative
longer bond length and larger bond angle between NHC ligand and iridium center may be
(

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reasonably to explain the difficulty of synthesizing NHC-based iridium complex.[50-52]
Figure 1. Crystal structure of Irppyimac. The hydrogen atoms are omitted for clarity.
Table 1. Selected bond length (Å) and angles (°) for Irppyimac.
Selected bond length
Ir(1)-C(18)
Ir(1)-N(4)
Ir(1)-N(3)
Ir(1)-C(7)
Ir(1)-C(3)
Ir(1)-O(1)
1.993(6)
2.055(5)
2.052(4)
2.054(6)
2.097(6)
2.185(4)
Selected bond angles
C(18)-Ir(1)-N(4) 80.8(2)
C(7)-Ir(1)-N(3)
C(3)-Ir(1)-O(1)
N(4)-Ir(1)-N(3)
79.9(2)
85.50(19)
172.91(19)

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C(18)-Ir(1)-C(7) 86.1(2)
Photophysical Properties and Theoretical Analysis
Figure 2 displayed the absorption and photoluminescent spectra of Irppyimac in acetonitrile
solution. Notably, this novel NHC-based iridium complex exhibited strong intraligand absorption
-1
-1
bands (π-π*) below 300 nm (ε > 10000 M cm , ε is molar extinction coefficient) and weaker
MLCT (metal to ligand charge transfer) transition bands from 350 to 500 nm, and while there is
almost no absorption band above 500 nm. Such a feature is very similar to other reported iridium
complexes.[52, 56]
Under the excitation of 395 nm as the representative wavelength of the MLCT state, the
photoluminescent spectrum of Irppyimac has been recorded as shown in Figure 2B. The major
emission peak is centered at 513 nm, which is very close to its analogue of
2
bis(2-phenylpyridine-C ,N’)(acetoylacetonate)iridium(III) with the same main ligand of
2
-phenylpyridine.[63] Such phenomenon revealed that the emission colors of the heteroleptical
iridium complexes are intensely related with the nature of main ligand. Furthermore, according to
2
the former reported methodand using fac-tri(2-phenylpyridine-C ,N’) iridium(III)) (abbreviated as
fac-Ir(ppy) ) as the reference,[64, 65] the quantum efficiency of Irppyimac in deaerated
3
acetonitrile solution have also been calculated to be 17.8%, which demonstrates that this novel
NHC-based iridium(III) complex has comparatively excellent photoluminescent properties.

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Figure 2. The absorption (A) and normalized photoluminescent spectra (B) of Irppyimac in
acetonitrile solution. ε is the molar extinction coefficient, excitation wavelength is 395 nm.
In order to further investigate the nature of this novel NHC-based iridium(III) complex,
density function theory (DFT) and time dependent density function theory (TD-DFT) have also
been used to calculate the ground and excited states of Irppyimac using Gaussian 09 package.
The 6-31+G(d) basis set was used for C, N, H, O, and the iridium atom employed the LANL2DZ
basis set, which have been proven reliable for iridium(III) complexes.[66, 67] The electron
distributions on frontier orbitals involving the singlet and triplet states of Irppyimac have been
shown in Figure 3, and the calculated transition wavelength and assignment are also listed in Table
2
.
According to Figure 3, the HOMO and HOMO-1 of Irppyimac have the mixture electron
distributions both on main ligand and NHC-based ancillary ligand, while the electrons of LUMO
and LUMO+1 are mainly located on main ligand. In addition with the assignment of singlet (S1)
and triplet (T ) state from the TD-DFT calculation results, the main character natures of S and T
1
1
1
state could be reasonable ascribed to the mixture of metal to ligand charge transfer (MLCT) and
ligand to ligand charge transfer (LLCT).

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Figure 3. The electronic distributions on frontier orbitals and corresponding energy level of
Irppyimac based on the optimized structure of the ground state.
Table 2. TD-DFT calculation results of Irppyimac.
State Energy
λ
max
f
Assignments
[
eV]
[nm]
484
T
1
2.56
0.0000 HOMO→LUMO (61.23%)
HOMO-1→LUMO (11.95%)
HOMO→LUMO+1 (+23.17%)
S
1
2.80
443
0.0260 HOMO→LUMO (68.76%)
Electrochemistry and Electrochemiluminescence
It’s well known that the redox properties are highly related with ECL of luminophore,
therefore, cyclic voltammetry (CV) was employed to investigate the redox character of Irppyimac.
Figure 4 shows the CV curve of 1 mM Irppyimac in deaerated acetonitrile solution on the surface
of Pt working electrode. All the potentials listed in this work are all calibrated to
+
ferrocene/ferrocenium (Fc/Fc ). Accordingly, one reversible oxidation peak has been observed at
ox
Pt electrode with the scan rate of 0.1 V/s. The half peak oxidative potential (E1/2 ) is 0.62 V and
the ∆E is 77 mV. Meanwhile, there is no obvious reduction peaks until scanning negative to -1.8
P
V except a small peak recorded at ca. -0.75 V. Importantly, compared with the oxidative potential

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2
+
of the widely-used tris(2,2’-bipyridyl)ruthenium(II) (abbreviated as Ru(bpy)3 ),[24] this novel
+
NHC-based iridium complex has much lower oxidative potential (<0.8 V vs Fc/Fc ), which has
many advantages in the real applications.[37]
Figure 4. Cyclic voltammograms of 1mM Irppyimac in acetonitrile solution containing 0.1 M
TBAPF after pumping N atmosphere for 15 minutes. Scan rate: 0.1V/s, Pt electrode area: 3.14
6
2
2
mm .
Co-reactant assisted ECL is one of the most important pathway for ECL generation, which
has also been successfully used in the commercialized ECL immunoassay system based on
ruthenium complex.[68, 69] According to the redox nature of Irppyimac as shown in Figure 4, the
type of oxidative-reduction co-reactant should be our best choice to generate ECL of this novel
luminophores. However, as for how to select the best co-reactant for a novel luminophore, there is
still no general answer so far. As we know, though there are a large number of researches focusing
on exploiting new ECL luminophores,[31, 35, 37, 38, 70-72] tri-n-propylamine (TPA) is always
widely used as an important co-reactant in the emerging iridium(III)-based luminophores. Though
there are some reports focusing on the studies of co-reactants, [73-77] it’s still very important to

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optimize the co-reactant especially for the new luminophore.
Herein, in this work, five alkyl amines including tri-n-propylamine (TPA), triethylamine
(
TEA), dimethylethanolamine (DMEA), diisopropylethylamine (DIPEA) and diisopropylamine
DIPA) have all been selected as the co-reactants to assist the ECL generation of this novel
(
NHC-based iridium complex. Due to the importance of oxidation potential of co-reactant for the
ECL generation, the oxidative curves of these five alkyl amines are also investigated and listed in
Figure S4 in supplementary material. According to Figure S4, all these five alkyl amine display an
irreversible oxidation peak on Pt electrode in acetonitrile solution. The sequence of the oxidation
peak potential is TEA (0.67 V) > DMEA (0.64 V) > DIPA (0.62 V) > TPA (0.57 V) > DIPEA (0.44
V). Subsequently, the ECL of Irppyimac assisted by these five alkyl amine have been
investigated and listed in Figure 5A to Figure 5E, respectively. It’s found that an apparent ECL
signal has all been observed along with the oxidation of the co-reactant and Irppyimac. Though
ECL signals of Irppyimac are all found in these five alkyl amines assisted ECL system, the ECL
intensities are much variable with the type of co-reactant in Figure 5(from A to E). The integrated
ECL intensity of Irppyimac follows the sequence: TEA>DIPA>DIPEA>TPA>DMEA.
Interestingly, the ECL intensity of Irppyimac with TEA (Figure 5B) is about 3 times higher than
that with TPA (Figure 5A). Furthermore, based on the former reported method,[23] after pulsing
the potential from 0 to 100 mV over the peak potential of Irppyimac, the ECL spectrum of
Irppyimac with TEA has also been characterized and listed in Figure 5F. The ECL spectrum is
centered at 508 nm and it’s very close to the major peak of PL spectra located at 513 nm. It should
be noted that compared with the heteroleptic iridium(III) complexes with the traditional O^O or
N^O ancillary ligands,[22, 23, 38] the ECL spectra of this novel heteroleptic iridium(III) complex

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with NHC ancillary ligand showed obviously blue-shift, which may be helpful to design deep-blue
ECL dyes and develop multichannel analytical techniques in the future.
To the best of our knowledge, theoretical calculations have been employed to try to explain
the relationship between ECL intensity and frontier orbital energy levels of the radicals of
co-reactant,[78] and higher HOMO level of co-reactant radical has been proven to be in favor of
increasing the ECL intensity of luminophores.[56, 67, 79] According to former literatures,[56, 67]
the ground state geometries of these final alkyl amines were finally optimized in the absence of
solvent with mPW1PW91[80] functional in conjunction with 6-31G basis set. The calculation
results demonstrate that the HOMO energy levels of these co-reactants’ radicals obey the
following sequences: DIPEA(-3.2 eV)>TEA(-3.3 eV)=TPA(-3.3 eV)>DIPA(-3.4 eV)>DMEA(-3.6
eV). For DMEA, the theoretical result is in consistent with its ECL experimental result (i.e. the
lowest HOMO energy level of the co-reactant radical is usually predicated to be the weakest ECL
signal in the oxidative-reduction co-reactant assisted ECL pathway according to the former
researches. [56, 67, 79]). While for the co-reactants of TPA, TEA, DIPEA and DIPA, due to the
similarity of their chemical structures, they have very very similar HOMO energy levels and there
is some discrepancy order between theoretical results and experimental results, which may be
reasonably explained by the complexities of the chemical and electrochemical reactions involved
in the ECL generation.[36]
In brief, TEA has been proven as the best co-reactant for Irppyimac and this novel
NHC-based iridium complex displays green ECL emission centered at 508 nm under the
assistance of TEA.

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Figure 5. (A-E) The CV and ECL curves of 1 mM Irppyimac versus potentials in
acetonitrile solution containing 0.1 M TBAPF and 10 mM coreactant after pumping N2
6
atmosphere for 15 minutes. Scan rate: 0.1 V/s, the coreactant used in figure A to figure E is
tri-n-propylamine (TPA), triethylamine (TEA), dimethylethanolamine (DMEA),
diisopropylethylamine (DIPEA) and diisopropylamine (DIPA), respectively. (F) The
normalized ECL spectra of 1 mM Irppyimac in acetonitrile solution containing 10 mM TEA
and 0.1 M TBAPF . Potentials pulsing from 0 to 100 mV over the oxidative potential of
6
Irppyimac.
Conclusion
An imidazolium bromide with carboxylic acid has been designed and synthesized as the

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NHC precursor through quaternary ammonium reaction between 1-methyl-1H-imidazole and
2
-bromoacetic acid. Subsequently, through metal-transfer reaction between silver and
iridium(III), a novel green emissive iridium(III) complex with NHC-based ancillary ligand
have been synthesized and thoroughly investigated through chemical structural photophysical,
electrochemical and theoretical calculation methods in this work. Most importantly, based on
this novel ECL luminophores, five alkyl amines are selected as the oxidative-reduction
co-reactants to comprehensively investigate the relationships between ECL intensity and
co-reactant by experimental and theoretical calculation method in this work. Triethylamine
(
TEA), rather than TPA, has been proven to be the best co-reactant for this novel ECL
luminophore. This study not only would pave the road of exploiting excellent co-reactant
systems for the emerging iridium-based ECL luminophores, but also could shed light on the
design of new type NHC-based bidentate ligand (Ccarbene^O) coordinated to iridium and enrich
luminescent NHC-based iridium(III) complexes in the future.
Experimental section
Materials. All chemicals involving the synthesis of iridium complexes were all purchased
from commercial sources and used without further purification. Spectrum pure (SP)-grade
acetonitrile for absorption and photoluminescent spectra were purchased from Sinopharm
Chemical Reagent Co. Ltd, while extra-dry acetonitrile, ferrocene, tri-n-propylamine (TPA),
triethylamine (TEA), dimethylethanolamine (DMEA), diisopropylethylamine (DIPEA),
diisopropylamine (DIPA) and tetra-n-butylammonium hexafluorophosphate (TBAPF ) for
6
electrochemistry and ECL characterization were obtained from Energy Chemical Inc.
(
Shanghai, China) without further purification.

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1
13
Apparatus and Methods. H-NMR and C-NMR spectra were acquired on a VARIAN-400
magnetic resonance spectrophotometer. Mass spectra were measured on a Varian ProStar
LC240 (America). UV−vis spectra and photoluminescent spectra were recorded UV-vis
spectrophotometer (TU-1950, Beijing Purkinje General Instrument Co., Ltd, Beijing, China)
and Edinburgh FLS980 type steady-state/transient spectrometer.
Three-electrode setup was used for electrochemical and ECL experiments. A Pt disk
sealed in polytetrafluoroethylene (PTFE) was used as the working electrode and two Pt wires
were for the auxiliary electrode and quasi-reference electrode, respectively. Before each
experiment, the working electrode was all polished with alumina (0.05 µm) for several
minutes, sonicated in water and in ethanol for 5 min each, and finally dried in an oven at
+
1
20 °C. Ferrocene/ferrocenium (Fc/Fc ) was used to calibrate the potentials in this work. Both
CV and ECL intensity were all recorded on a MPI-EII ECL detector (Xi’an Remax
Electronics, China) equipped with a photomultiplier tube (Model: R9880U-20, Hamamatsu,
Japan). The ECL spectra were recorded by pulsing from 0 to 100 mV past oxidation potential
of iridium(III) complexes with a step time of 0.1 s using TEA as a co-reactant.
Theoretical calculations. Density function theory (DFT) and time dependent density function
theory (TD-DFT) have also been used to calculate the ground and excited states of Irppyimac
using Gaussian 09 package, respectively. The 6-31+G(d) basis set was used for C, N, H, O, and
the iridium atom employed the LANL2DZ basis set. The ground state geometries of these final
alkyl amine radicals are optimized in the absence of solvent with mPW1PW91[80] functional in
conjunction with 6-31G basis set.
Synthesis and Characterization

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Imidazolium bromide. An acetonitrile solution of 1-methyl-1H-imidazole (1.64 g, 20 mmol)
and 2-bromo-acetic acid (2.78 g, 20 mmol) were refluxed for 24 hours under nitrogen
atmosphere. After cooling to room temperature, the solvent was evaporated under reduced
pressure. The formed oil was purified by repetitive re-crystallization from THF/CH OH and
3
1
the colorless crystalline product was finally obtained. Yield: 3.9 g (88%). H-NMR (400 MHz,
1
3
CD OD), δ (ppm): 9.02 (s, 1 H), 7.65-7.62 (m, 2 H), 5.16 (s, 2 H), 3.99 (s, 3 H). C-NMR
3
(
376 MHz, CD OD), δ (ppm):169.08, 139.22, 125.07, 124.53, 50.78, 36.73.
3
Ag carbene. A little modification procedure reported by Wang was used.[62] Ag O (232 mg,
2
1
mmol) was added to the solution of Imidazolium bromide (444 mg, 2 mmol) in
dichloromethane (50 mL). The solution was stirred and refluxed for 12 hours with nitrogen
atmosphere under dark condition. And then cooling to room temperature and filtration, the
solvent in filtrate was evaporated under reduced pressure. After drying under vacuum
condition, the yellowish-brown crystalline product (620 mg) was obtained and used in the
next step without further purification.
Iridium(III) dichlorobridged dimer. A solution of IrCl ·3H O (706 mg, 2 mmol) and
3
2
2
-phenylpyridine (620 mg, 4 mmol) in the mixture of 2-ethoxyethanol/H O (V:V=3:1) was
2
refluxed for 24 hours under nitrogen atmosphere. After cooling to room temperature, the
solution was filtrated and the precipitate was successively washed with water, ethanol and
n-hexane. The iridium(III) dichlorobridged dimer (980 mg) was obtained after drying and
used in the next step without further purification.
Irppyimac. Potassium carbonate (685 mg, 5 mmol) was added to the solution of iridium(III)
dichlorobridged dimer (536 mg, 0.5 mmol) and Ag carbene (329 mg, 0.5 mmol) in xylenes

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(
100 mL). The mixtures was stirred and refluxed for 24 hours under dark condition with
nitrogen protection. And then cooling to the room temperature, the solvent was evaporated
under reduced pressure. The residues were chromatographed on a silica gel column with
CH Cl /CH OH and the purified product (yellowish-green powder) was obtained after drying
2
2
3
1
under vacuum condition. Yield: 326 mg (51%), UPLC purity: 99%. H-NMR (400 MHz,
CDCl ), δ (ppm): 8.94 (m, 1 H), 8.34 (m, 1 H), 7.88 (m, 2 H), 7.77 (m, 2 H), 7.58 (dd, J=6.4,
3
1
.2 Hz, 1 H), 7.52 (dd, J=6.4, 1.2 Hz, 1 H), 7.14 (m, 1 H), 7.00 (m, 1 H), 6.89 (d, J=2 Hz, 2
H), 6.85-6.75 (m, 2 H), 6.65 (td, J=7.6, 1.2 Hz, 1 H), 6.62 (d, J=2 Hz, 1 H), 6.36 (dd, J= 8, 1.2
1
3
Hz, 1 H), 5.98 (dd, J=7.2, 0.8 Hz, 1 H), 4.53 (s, 2 H), 2.64 (s, 3 H). C-NMR (376 MHz,
CDCl ), δ (ppm):172.441, 171.366, 171.241, 167.267, 165.065, 152.162, 149.290, 147.513,
3
1
1
44.264, 143.209, 136.803, 135.985, 131.120, 130.964, 129.866, 129.144, 124.292, 123.825,
22.230, 122.184, 121.999, 121.804, 121.334, 119.749, 119.696, 118.056, 54.980, 36.516.
Tof-Ms: m/z (experimental) 639.1491, m/z (calculated) 639.1500.
Acknowledgement
The authors are grateful to National Natural Science Foundation of China (NSFC No. 21505097);
Natural Science Foundation of Jiangsu Province (BK20150283); University Scientific Research
Project of Jiangsu Province (15KJB150027); the Priority Academic Program Development of
Jiangsu Higher Education Institutions (PAPD); Excellent Innovation Team in Science and
Technology of University in Jiangsu Province and Jiangsu Collaborative Innovation Center of
Technology and Material for Water Treatment for financial support. We also thank to
Supercomputing Center, CNIC, CAS for the calculation supporting.
References

ACCEPTED MANUSCRIPT
[
1] N.E. Tokel, A.J. Bard, Electrogenerated chemiluminescence. IX. Electrochemistry and emission
from systems containing tris(2,2'-bipyridine)ruthenium(II) dichloride, J. Am. Chem. Soc., 94 (1972)
2
862-2863.
[
2] N.E. Tokel-Takvoryan, R.E. Hemingway, A.J. Bard, Electrogenerated chemiluminescence. XIII.
Electrochemical and electrogenerated chemiluminescence studies of ruthenium chelates, J. Am. Chem.
Soc., 95 (1973) 6582-6589.
[
3] L. Hu, G. Xu, Applications and trends in electrochemiluminescence, Chem. Soc. Rev., 39 (2010)
3
275-3304.
[
(
[
4] W. Miao, Electrogenerated Chemiluminescence and Its Biorelated Applications, Chem. Rev., 108
2008) 2506-2553.
5] L. Hu, G. Xu, Applications and trends in electrochemiluminescence, Chem. Soc. Rev., 39 (2010)
3
275-3304.
[
6] A. Kapturkiewicz, Cyclometalated iridium(III) chelates—a new exceptional class of the
electrochemiluminescent luminophores, Anal. Bioanal. Chem., (2016) 1-21.
[
7] Z. Liu, W. Qi, G. Xu, Recent advances in electrochemiluminescence, Chem. Soc. Rev., 44 (2015)
3
117-3142.
[
8] M.M. Richter, A.J. Bard, Electrogenerated Chemiluminescence. 58. Ligand-Sensitized
Electrogenerated Chemiluminescence in Europium Labels, Anal. Chem., 68 (1996) 2641-2650.
[
9] M.M. Richter, J.D. Debad, D.R. Striplin, G.A. Crosby, A.J. Bard, Electrogenerated
Chemiluminescence. 59. Rhenium Complexes, Anal. Chem., 68 (1996) 4370-4376.
[
10] J. McCall, D. Bruce, S. Workman, C. Cole, M.M. Richter, Electrochemiluminescence of Copper(I)
Bis(2,9-dimethyl-1,10-phenanthroline), Anal. Chem., 73 (2001) 4617-4620.

ACCEPTED MANUSCRIPT
2+
[
11] D. Bruce, M.M. Richter, K.J. Brewer, Electrochemiluminescence from Os(phen) (dppene) (phen
2
=
1,10-phenanthroline and dppene = bis(diphenylphosphino)ethene), Anal. Chem., 74 (2002)
3
157-3159.
[
12] J.D. Anderson, E.M. McDonald, P.A. Lee, M.L. Anderson, E.L. Ritchie, H.K. Hall, T. Hopkins,
E.A. Mash, J. Wang, A. Padias, S. Thayumanavan, S. Barlow, S.R. Marder, G.E. Jabbour, S. Shaheen,
B. Kippelen, N. Peyghambarian, R.M. Wightman, N.R. Armstrong, Electrochemistry and
Electrogenerated
Chemiluminescence
Processes
of the
Components
of
Aluminum
Quinolate/Triarylamine, and Related Organic Light-Emitting Diodes, J. Am. Chem. Soc., 120 (1998)
9
646-9655.
[
13] E.M. Gross, J.D. Anderson, A.F. Slaterbeck, S. Thayumanavan, S. Barlow, Y. Zhang, S.R. Marder,
H.K. Hall, M.F. Nabor, J.F. Wang, E.A. Mash, N.R. Armstrong, R.M. Wightman, Electrogenerated
Chemiluminescence from Derivatives of Aluminum Quinolate and Quinacridones:ꢀ Cross-Reactions
with Triarylamines Lead to Singlet Emission through Triplet−Triplet Annihilation Pathways, J. Am.
Chem. Soc., 122 (2000) 4972-4979.
[
14] S. Kulmala, M. Håkansson, A.M. Spehar, A. Nyman, J. Kankare, K. Loikas, T. Ala-Kleme, J.
Eskola, Heterogeneous and homogeneous electrochemiluminoimmunoassays of hTSH at disposable
oxide-covered aluminum electrodes, Anal. Chim. Acta, 458 (2002) 271-280.
[
15] E.M. Gross, N.R. Armstrong, R.M. Wightman, Electrogenerated Chemiluminescence from
Phosphorescent Molecules Used in Organic Light-Emitting Diodes, J. Electrochem. Soc., 149 (2002)
E137-E142.
[
16] D. Bruce, M.M. Richter, Green electrochemiluminescence from ortho-metalated
tris(2-phenylpyridine)iridium(III), Anal. Chem., 74 (2002) 1340-1342.

ACCEPTED MANUSCRIPT
[
17] A. Kapturkiewicz, G. Angulu, Extremely efficient ECL systems based on
tris(2-phenylpyridine)iridium(III), Dalton Trans., (2003) 3907-3913.
[
18] B.D. Muegge, M.M. Richter, Multicolored electrogenerated chemiluminescence from
ortho-metalated iridium(III) systems, Anal. Chem., 76 (2004) 73-77.
[
19] J.I. Kim, I.-S. Shin, H. Kim, J.-K. Lee, Efficient Electrogenerated Chemiluminescence from
Cyclometalated Iridium(III) Complexes, J. Am. Chem. Soc., 127 (2005) 1614-1615.
[
20] M.J. Li, P. Jiao, M. Lin, W. He, G.N. Chen, X. Chen, High electrochemiluminescence of a new
water-soluble iridium(III) complex for determination of antibiotics, Analyst, 136 (2011) 205-210.
[
21] C. Li, J. Lin, Y. Guo, S. Zhang, A novel electrochemiluminescent reagent of cyclometalated
iridium complex-based DNA biosensor and its application in cancer cell detection, Chem. Commun.,
4
7 (2011) 4442-4444.
[
22] W. Yang, D. Wang, Q. Song, S. Zhang, Q. Wang, Y. Ding, Phosphorescent Cyclometalated
Iridium(III) Complexes Based on Amidate Ancillary Ligands: Their Synthesis and Photophysical
Properties, Organometallics, 32 (2013) 4130-4135.
[
23] Y. Zhou, H. Gao, X. Wang, H. Qi, Electrogenerated Chemiluminescence from Heteroleptic
Iridium(III) Complexes with Multicolor Emission, Inorg. Chem., 54 (2015) 1446-1453.
[
24] Y. Zhou, W. Li, L. Yu, Y. Liu, X. Wang, M. Zhou, Highly Efficient Electrochemiluminescence
from Iridium(III) Complexes with 2-Phenylquinoline Ligand, Dalton Trans., 44 (2015) 1858-1865.
[
25] X. Yang, G. Zhou, W.-Y. Wong, Recent design tactics for high performance white polymer
light-emitting diodes, J. Mater. Chem. C, 2 (2014) 1760-1778.
[
26] X. Yang, G. Zhou, W.-Y. Wong, Functionalization of phosphorescent emitters and their host
materials by main-group elements for phosphorescent organic light-emitting devices, Chem. Soc. Rev.,

ACCEPTED MANUSCRIPT
4
4 (2015) 8484-8575.
[
27] C.-L. Ho, H. Li, W.-Y. Wong, Red to near-infrared organometallic phosphorescent dyes for OLED
applications, J. Organomet. Chem., 751 (2014) 261-285.
[
28] J. Sun, J. Yang, C. Zhang, H. Wang, J. Li, S. Su, H. Xu, T. Zhang, Y. Wu, W.-Y. Wong, B. Xu, A
novel white-light-emitting conjugated polymer derived from polyfluorene with a hyperbranched
structure, New J. Chem., 39 (2015) 5180-5188.
[
29] C.-L. Ho, W.-Y. Wong, Charge and energy transfers in functional metallophosphors and
metallopolyynes, Coord. Chem. Rev., 257 (2013) 1614-1649.
[
30] X. Xu, X. Yang, J. Zhao, G. Zhou, W.-Y. Wong, Recent Advances in Solution-Processable
Dendrimers for Highly Efficient Phosphorescent Organic Light-Emitting Diodes (PHOLEDs), Asian
Journal of Organic Chemistry, 4 (2015) 394-429.
[
31] Y. Zhou, K. Xie, R. Leng, L. Kong, C. Liu, Q. Zhang, X. Wang, Highly efficient
electrochemiluminescence labels comprising iridium(iii) complexes, Dalton Trans., 46 (2017) 355-363.
[
32] K.N. Swanick, S. Ladouceur, E. Zysman-Colman, Z. Ding, Bright electrochemiluminescence of
iridium(iii) complexes, Chem. Commun., 48 (2012) 3179-3181.
[
33] M. Bandini, M. Bianchi, G. Valenti, F. Piccinelli, F. Paolucci, M. Monari, A. Umani-Ronchi, M.
Marcaccio, Electrochemiluminescent Functionalizable Cyclometalated Thiophene-Based Iridium(III)
Complexes, Inorg. Chem., 49 (2010) 1439-1448.
[
34] S. Zanarini, M. Felici, G. Valenti, M. Marcaccio, L. Prodi, S. Bonacchi, P. Contreras-Carballada,
R.M. Williams, M.C. Feiters, R.J.M. Nolte, L. De Cola, F. Paolucci, Green and Blue Electrochemically
Generated Chemiluminescence from Click Chemistry—Customizable Iridium Complexes, Chem. Eur.
J., 17 (2011) 4640-4647.

ACCEPTED MANUSCRIPT
[
35] H. Gao, S. Xia, R. Zhang, Y. Zhao, W. Wang, Z. An, H. Qi, Efficient green electrogenerated
chemiluminescence from cyclometalated iridium (III) complex, J. Electroanal. Chem., 755 (2015)
7
1-76.
[
36] E. Kerr, E.H. Doeven, D.J.D. Wilson, C.F. Hogan, P.S. Francis, Considering the chemical energy
requirements of the tri-n-propylamine co-reactant pathways for the judicious design of new
electrogenerated chemiluminescence detection systems, Analyst, 141 (2016) 62-69.
[
37] Y. Zhao, X. Yang, D. Han, H. Qi, Q. Gao, C. Zhang, Cyclometalated Iridium-Complex-Based
Label-Free Supersandwich Electrogenerated Chemiluminescence Biosensor for the Detection of
Micro-RNA, ChemElectroChem, (2017) n/a-n/a.
[
38] S. Xia, D. Han, H. Gao, Y. Zhao, H. Qi, C. Zhang, Electrogenerated chemiluminescence of
cyclometalated iridium(III) complexes with derived β-acetylacetone as ancillary ligand, J. Electroanal.
Chem., 777 (2016) 101-107.
[
39] A.J. Arduengo, R.L. Harlow, M. Kline, A stable crystalline carbene, J. Am. Chem. Soc., 113 (1991)
3
61-363.
[
(
[
40] C. Jandl, A. Pothig, A hybrid carbocyclic/N-heterocyclic carbene ligand, Chem. Commun., 53
2017) 2098-2101.
41] S.U. Son, K.H. Park, Y.-S. Lee, B.Y. Kim, C.H. Choi, M.S. Lah, Y.H. Jang, D.-J. Jang, Y.K. Chung,
Synthesis of Ru(II) Complexes of N-Heterocyclic Carbenes and Their Promising Photoluminescence
Properties in Water, Inorg. Chem., 43 (2004) 6896-6898.
[
42] H.M.J. Wang, C.Y.L. Chen, I.J.B. Lin, Synthesis, Structure, and Spectroscopic Properties of
Gold(I)−Carbene Complexes, Organometallics, 18 (1999) 1216-1223.
[
43] F.-F. Hung, W.-P. To, J.-J. Zhang, C. Ma, W.-Y. Wong, C.-M. Che, Water-Soluble Luminescent

ACCEPTED MANUSCRIPT
Cyclometalated Gold(III) Complexes with cis-Chelating Bis(N-Heterocyclic Carbene) Ligands:
Synthesis and Photophysical Properties, Chem. Eur. J., 20 (2014) 8604-8614.
[
44] B. Liu, W. Chen, S. Jin, Synthesis, Structural Characterization, and Luminescence of New Silver
Aggregates Containing Short Ag−Ag Contacts Stabilized by Functionalized Bis(N-heterocyclic carbene)
Ligands, Organometallics, 26 (2007) 3660-3667.
[
45] W.-M. Xue, M.C.-W. Chan, Z.-M. Su, K.-K. Cheung, S.-T. Liu, C.-M. Che, Spectroscopic and
Excited-State Properties of Luminescent Rhenium(I) N-Heterocyclic Carbene Complexes Containing
Aromatic Diimine Ligands, Organometallics, 17 (1998) 1622-1630.
[
46] Y. Unger, A. Zeller, S. Ahrens, T. Strassner, Blue phosphorescent emitters: new N-heterocyclic
platinum(ii) tetracarbene complexes, Chem. Commun., (2008) 3263-3265.
[
47] S.K. Fung, T. Zou, B. Cao, T. Chen, W.-P. To, C. Yang, C.-N. Lok, C.-M. Che, Luminescent
platinum(II) complexes with functionalized N-heterocyclic carbene or diphosphine selectively probe
mismatched and abasic DNA, Nature Communications, 7 (2016) 10655-10663.
[
48] V.A. Krylova, P.I. Djurovich, J.W. Aronson, R. Haiges, M.T. Whited, M.E. Thompson, Structural
and Photophysical Studies of Phosphorescent Three-Coordinate Copper(I) Complexes Supported by an
N-Heterocyclic Carbene Ligand, Organometallics, 31 (2012) 7983-7993.
[
49] R. Visbal, M.C. Gimeno, N-heterocyclic carbene metal complexes: photoluminescence and
applications, Chem. Soc. Rev., 43 (2014) 3551-3574.
[
50] T. Sajoto, P.I. Djurovich, A. Tamayo, M. Yousufuddin, R. Bau, M.E. Thompson, R.J. Holmes, S.R.
Forrest, Blue and near-UV phosphorescence from iridium complexes with cyclometalated pyrazolyl or
N-heterocyclic carbene ligands, Inorg. Chem., 44 (2005) 7992-8003.
[
51] C.H. Chien, S. Fujita, S. Yamoto, T. Hara, T. Yamagata, M. Watanabe, K. Mashima, Stepwise and

ACCEPTED MANUSCRIPT
one-pot syntheses of Ir(III) complexes with imidazolium-based carbene ligands, Dalton Trans., (2008)
9
16-923.
[
52] Y. Zhou, J. Jia, W. Li, H. Fei, M. Zhou, Luminescent biscarbene iridium(iii) complexes as living
cell imaging reagents, Chem. Commun., 49 (2013) 3230-3232.
[
53] K.-Y. Lu, H.-H. Chou, C.-H. Hsieh, Y.-H.O. Yang, H.-R. Tsai, H.-Y. Tsai, L.-C. Hsu, C.-Y. Chen,
I.C. Chen, C.-H. Cheng, Wide-Range Color Tuning of Iridium Biscarbene Complexes from Blue to
Red by Different N^N Ligands: an Alternative Route for Adjusting the Emission Colors, Adv. Mater.,
2
3 (2011) 4933-4937.
[
54] C.H. Hsieh, F.I. Wu, C.H. Fan, M.J. Huang, K.Y. Lu, P.Y. Chou, Y.H. Yang, S.H. Wu, I.C. Chen,
S.H. Chou, K.T. Wong, C.H. Cheng, Design and Synthesis of Iridium Bis(carbene) Complexes for
Efficient Blue Electrophosphorescence, Chem. Eur. J., 17 (2011) 9180-9187.
[
55] H. Sasabe, J.-i. Takamatsu, T. Motoyama, S. Watanabe, G. Wagenblast, N. Langer, O. Molt, E.
Fuchs, C. Lennartz, J. Kido, High-Efficiency Blue and White Organic Light-Emitting Devices
Incorporating a Blue Iridium Carbene Complex, Adv. Mater., 22 (2010) 5003-5007.
[
56] B.D. Stringer, L.M. Quan, P.J. Barnard, D.J.D. Wilson, C.F. Hogan, Iridium Complexes of
N-Heterocyclic Carbene Ligands: Investigation into the Energetic Requirements for Efficient
Electrogenerated Chemiluminescence, Organometallics, 33 (2014) 4860-4872.
[
57] D. Bourissou, O. Guerret, F.P. Gabbai, G. Bertrand, Stable carbenes, Chem. Rev., 100 (2000)
3
9-91.
[
58] F. Monti, F. Kessler, M. Delgado, J. Frey, F. Bazzanini, G. Accorsi, N. Armaroli, H.J. Bolink, E.
Ortí, R. Scopelliti, M.K. Nazeeruddin, E. Baranoff, Charged Bis-Cyclometalated Iridium(III)
Complexes with Carbene-Based Ancillary Ligands, Inorg. Chem., 52 (2013) 10292-10305.

ACCEPTED MANUSCRIPT
[
59] D.R. Weinberg, N. Hazari, J.A. Labinger, J.E. Bercaw, Iridium(I) and Iridium(III) Complexes
Supported by a Diphenolate Imidazolyl-Carbene Ligand, Organometallics, 29 89-100.
[
60] S. Lamansky, P. Djurovich, D. Murphy, F. Abdel-Razzaq, H.-E. Lee, C. Adachi, P.E. Burrows, S.R.
Forrest, M.E. Thompson, Highly phosphorescent bis-cyclometalated iridium complexes: synthesis,
photophysical characterization, and use in organic light emitting diodes, J. Am. Chem. Soc., 123 (2001)
4
304-4312.
[
61] N. Matsuo, Benzo[h]quinolin-10-yl-N Iridium(III) Complexes, Bull. Chem. Soc. Jpn., 47 (1974)
7
67-768.
[
62] H.M.J. Wang, I.J.B. Lin, Facile Synthesis of Silver-Carbene Complexes. Useful Carbene Transfer
Agents, Organometallics, 17 (1998) 972-975.
[
63] M.K. Nazeeruddin, R. Humphry-Baker, D. Berner, S. Rivier, L. Zuppiroli, M. Graetzel, Highly
Phosphorescence Iridium Complexes and Their Application in Organic Light-Emitting Devices, J. Am.
Chem. Soc., 125 (2003) 8790-8797.
[
64] K.A. King, P.J. Spellane, R.J. Watts, Excited-state properties of a triply ortho-metalated iridium(III)
complex, J. Am. Chem. Soc., 107 (1985) 1431-1432.
[
65] Y. Zhou, W. Li, Y. Liu, L. Zeng, W. Su, M. Zhou, Substituent effect of ancillary ligands on the
luminescence of bis[4,6-(di-fluorophenyl)-pyridinato-N,C2']iridium(III) complexes, Dalton Trans., 41
(
[
2012) 9373-9381.
66] L. Shi, B. Hong, W. Guan, Z. Wu, Z. Su, DFT/TD-DFT Study on the Electronic Structures and
Optoelectronic Properties of Several Blue-Emitting Iridium(III) Complexes, J. Phys. Chem. A, 114
(
[
2010) 6559-6564.
67] S. Zhu, Q. Song, S. Zhang, Y. Ding, Effects of the frontier orbitals on the electrochemical and

ACCEPTED MANUSCRIPT
electrochemiluminescent properties of the bis-cyclometalated iridium(III) complexes with different
ligands, J. Mol. Struct., 1035 (2013) 224-230.
[
68] G.F. Blackburn, H.P. Shah, J.H. Kenten, J. Leland, R.A. Kamin, J. Link, J. Peterman, M.J. Powell,
A. Shah, D.B. Talley, Electrochemiluminescence detection for development of immunoassays and
DNA probe assays for clinical diagnostics, Clin. Chem., 37 (1991) 1534-1539.
[
69] J.H. Kenten, J. Casadei, J. Link, S. Lupold, J. Willey, M. Powell, A. Rees, R. Massey, Rapid
electrochemiluminescence assays of polymerase chain reaction products, Clin. Chem., 37 (1991)
1
626-1632.
[
70] J.I. Kim, I.-S. Shin, H. Kim, J.-K. Lee, Efficient electrogenerated chemiluminescence from
cyclometalated iridium(III) complexes, J. Am. Chem. Soc., 127 (2005) 1614-1615.
[
71] S.-H. Zhang, J.-M. Wang, H.-Y. Zhang, Y.-P. Fan, Y. Xiao, Highly efficient
electrochemiluminescence based on 4-amino-1,2,4-triazole Schiff base two-dimensional Zn/Cd
coordination polymers, Dalton Trans., 46 (2017) 410-419.
[
72] F. Rizzo, F. Polo, G. Bottaro, S. Fantacci, S. Antonello, L. Armelao, S. Quici, F. Maran, From Blue
to Green: Fine-Tuning of Photoluminescence and Electrochemiluminescence in Bifunctional Organic
Dyes, J. Am. Chem. Soc., 139 (2017) 2060-2069.
[
73] G.J. Barbante, N. Kebede, C.M. Hindson, E.H. Doeven, E.M. Zammit, G.R. Hanson, C.F. Hogan,
P.S. Francis, Control of Excitation and Quenching in Multi-colour Electrogenerated
Chemiluminescence Systems through Choice of Co-reactant, Chem. Eur. J., 20 (2014) 14026-14031.
[
74] S.A. Kitte, C. Wang, S. Li, Y. Zholudov, L. Qi, J. Li, G. Xu, Electrogenerated chemiluminescence
of tris(2,2'-bipyridine)ruthenium(II) using N-(3-aminopropyl)diethanolamine as coreactant, Anal.
Bioanal. Chem., 408 (2016) 7059-7065.

ACCEPTED MANUSCRIPT
[
75] A. Jimenez-Ruiz, E. Grueso, P. Perez-Tejeda, F. Muriel-Delgado, C. Torres-Marquez,
Electrochemiluminescent (ECL) [Ru(bpy)3]2+/PAMAM dendrimer reactions: coreactant effect and
5
-fluorouracil/dendrimer complex formation, Anal. Bioanal. Chem., 408 (2016) 7213-7224.
[
76] Y.-P. Dong, Y. Zhou, J. Wang, J.-J. Zhu, Electrogenerated Chemiluminescence Resonance Energy
Transfer between Ru(bpy)32+ Electrogenerated Chemiluminescence and Gold Nanoparticles/Graphene
Oxide Nanocomposites with Graphene Oxide as Coreactant and Its Sensing Application, Anal. Chem.,
8
8 (2016) 5469-5475.
[
77] H. Li, A.C. Sedgwick, M. Li, R.A.R. Blackburn, S.D. Bull, S. Arbault, T.D. James, N. Sojic,
Selective electrochemiluminescent sensing of saccharides using boronic acid-modified coreactant,
Chem. Commun., 52 (2016) 12845-12848.
[
78] A. Kapturkiewicz, G. Angulo, Extremely efficient electrochemiluminescence systems based on
tris(2-phenylpyridine)iridium(iii), Dalton Trans., (2003) 3907-3913.
[
79] G.J. Barbante, E.H. Doeven, E. Kerr, T.U. Connell, P.S. Donnelly, J.M. White, T. Lópes, S. Laird,
D.J.D. Wilson, P.J. Barnard, C.F. Hogan, P.S. Francis, Understanding Electrogenerated
Chemiluminescence Efficiency in Blue-Shifted Iridium(III)-Complexes: An Experimental and
Theoretical Study, Chem. Eur. J., 20 (2014) 3322-3332.
[
80] C. Adamo, V. Barone, Exchange functionals with improved long-range behavior and adiabatic
connection methods without adjustable parameters: The mPW and mPW1PW models, J. Chem. Phys.,
1
08 (1998) 664-675.

ACCEPTED MANUSCRIPT
Highlights
1
2
. A novel NHC-based luminescent iridium(III) complexes have been synthesized.
. The synthesis, chemical structure, photophysical, theoretical calculations and
electrochemiluminescence properties have been thoroughly investigated in this work.
3
. Five alkyl amines have been employed to assist ECL generation of this novel
luminophores.
4
. The relationships between ECL intensity and co-reactant have been investigated.