36
N. Su, Y.-X. Zheng / Journal of Organometallic Chemistry 876 (2018) 35e42
phenyl)isoquinoline (tfmpiq) and 4-(4-(trifluoromethyl)phenyl)qui-
2.1. General synthesis of the Ir(III) complexes
nazoline (tfmpqz) were used as the main ligands, and 2-(3-methyl-
1H-pyrazol-5-yl)pyridine (mepzpy), 2-(3-(trifluoromethyl)-1H-pyr-
The mixture of main ligand (tfmpiq or tfmpqz) (2.70 mmol) and
azol-5-yl)pyridine (cf3pzpy) were applied as the ancillary ligands,
respectively (Scheme 1). The introduction of tfmpiq and tfmpqz with
IrCl
(9 mL) and distilled water (3 mL) in N
after adding of distilled water (50 mL), the red chloro-bridged
2
dimmer precipitates ([(tfmpiq) Ir( -Cl)] or [(tfmpqz) Ir( -Cl)] )
were formed and collected, respectively. Then the suspension of the
red chloro-bridged dimmer (0.83 mmol), the different ancillary li-
3
.3H
2
O (0.38 g, 1.08 mmol) were refluxed in 2-ethoxyethanol
2
atmosphere for 24 h. Then
a large
the Ir(III) complexes, therefore it can shift the emission into the red
region. The with-drawing eCF group in the main ligand is beneficial
p-conjugation systems could lead to a narrow energy gap of
2
m
2
2
m
3
to increase steric hindrance of Ir(III) complexes and suppress triplet-
triplet annihilation (TTA) and raise the yield of vacuum sublimation.
Moreover, the lower vibrational frequency of the CeF bond can
reduce the rate of radiationless deactivation, fluorination in the li-
gands can also increase the efficiency of the complexes and devices.
Pyrazole pyridine derivatives (mepzpy and cf3pzpy) were denoted as
ancillary ligands and expected that they can greatly influence the
energy levels of the highest occupied molecular orbit (HOMO) and
the lowest unoccupied molecular orbit (LUMO) of the Ir(III) com-
plexes via the introduction of nitrogen atoms and affect the electron
mobility and emission colours of the Ir(III) complexes [49e52]. As a
result, the Ir(III) complexes exhibit different photoluminescent,
electrochemical and electroluminescent performances due to the
distinct molecular structures. Particularly, the device with PQZ-Ir4-
2 3
gands (2.07 mmol) and K CO (0.95 g, 6.90 mmol) were refluxed in
2-ethoxyethanol (10 mL) overnight. Then the mixture was extrac-
ted with DCM (2 ꢁ 50 mL) and washed with distilled water (50 mL).
After removing the organic solvent, the red solid was obtained by a
flash silica gel column using petroleum ether (PE)/ethyl acetate
(EA) (V/V ¼ 1/5), then the red crystals were formed by further
vacuum sublimation.
1
PIQ-Ir1-me (yield: 39%). H NMR (400 MHz, CDCl
3
)
d
8.98e8.90
(m,1H), 8.87 (dd, J ¼ 6.2, 3.4 Hz,1H), 8.31 (t, J ¼ 8.7 Hz, 2H), 7.88 (dd,
J ¼ 6.4, 3.1 Hz, 1H), 7.84 (dd, J ¼ 6.1, 3.3 Hz, 1H), 7.76e7.72 (m, 3H),
7.71e7.69 (m, 2H), 7.67e7.60 (m, 2H), 7.58 (d, J ¼ 6.4 Hz, 1H), 7.40
(dd, J ¼ 8.7, 6.0 Hz, 2H), 7.28 (d, J ¼ 6.8 Hz, 2H), 7.21 (dd, J ¼ 8.4,
1.3 Hz, 1H), 6.86e6.78 (m, 1H), 6.65 (d, J ¼ 1.2 Hz, 1H), 6.49 (s, 1H),
cf3 emitter showed the maximum current efficiency (
h
c,max) of
p,max) of 33.98 lm
with Commission Internationale de 1 Eclairage (CIE) colour
6.47 (s, 1H), 2.28 (s, 3H). HRMS (m/z): calcd for C41
H
27
F
6
IrN
5
ꢀ1
þ
4
0.04 cd A and the maximum power efficiency (
h
[MþH] 896.1800, found 896.1795.
ꢀ
1
0
1
W
PIQ-Ir2-cf3 (yield: 40%). H NMR (400 MHz, CDCl
3
)
d
8.98e8.92
coordinates at (0.58, 0.40).
(m, 1H), 8.88 (dd, J ¼ 6.2, 3.4 Hz, 1H), 8.35e8.26 (m, 2H), 7.90 (dd,
J ¼ 6.3, 3.3 Hz, 1H), 7.87e7.82 (m, 1H), 7.78 (dd, J ¼ 9.0, 5.4 Hz, 3H),
7.76e7.72 (m, 3H), 7.68 (d, J ¼ 6.4 Hz, 1H), 7.49 (dd, J ¼ 9.1, 6.0 Hz,
2
. Experimental section
2
H), 7.42 (d, J ¼ 6.4 Hz, 1H), 7.29 (t, J ¼ 7.7 Hz, 2H), 7.22 (d, J ¼ 7.2 Hz,
Scheme 1 shows the synthetic route of the Ir(III) complexes. The
experimental details and the corresponding methods were clearly
shown in Supporting Information (ESI). The synthesis of the ligands
1H), 7.04e6.95 (m, 2H), 6.67 (s, 1H), 6.43 (s, 1H). HRMS (m/z): calcd
þ
for C41
H F
24 9
IrN
5
[MþH] 950.1517, found 950.1514.
1
3
PQZ-Ir3-me (yield: 38%). H NMR (400 MHz, CDCl ) d 8.89 (d,
were according to our previous reports [53,54]. The
m
-chloro-
J ¼ 8.5 Hz, 1H), 8.82 (d, J ¼ 8.6 Hz, 1H), 8.47 (dd, J ¼ 8.4, 2.9 Hz, 2H),
8.43 (s, 1H), 8.32 (s, 1H), 8.12 (d, J ¼ 8.3 Hz, 1H), 8.07 (d, J ¼ 7.9 Hz,
1H), 7.97e7.91 (m, 2H), 7.87e7.76 (m, 2H), 7.68 (s, 2H), 7.46 (d,
J ¼ 5.4 Hz, 1H), 7.35 (d, J ¼ 7.2 Hz, 1H), 7.28 (s, 1H), 6.88 (s, 1H), 6.79
bridged dimers [(tfmpiq) Ir( -Cl)] and [(tfmpqz) Ir( -Cl)]
2
m
2
2
m
2
were
obtained according to general synthesis procedure [55]. All Ir(III)
complexes were successfully synthesized by a two-step method
and further purified by sublimation in vacuum [22,56,57]. The
(s, 1H), 6.63 (s, 1H), 6.49 (s, 1H), 2.30 (d, J ¼ 10.0 Hz, 3H). HRMS (m/
1
þ
finally Ir(III) complexes were characterized by H NMR, high reso-
z): calcd for C39
H
25
F
6
IrN
7
[MþH] 898.1705, found 898.1701.
1
lution mass spectrometer (HRMS).
3
PQZ-Ir4-cf3 (yield: 32%). H NMR (400 MHz, CDCl ) d 8.86 (dd,
Scheme 1. Synthetic route of the Ir(III) complexes.