obtained product was purified by column chromatography
(silica gel) (yield: 63%). 1H NMR (300 MHz; CDCl3) d (ppm):
8.82 (d, J = 2.07 Hz, 1H), 8.40 (d, J = 7.98 Hz, 1H), 8.20–8.12
(m, 2H), 8.02 (td, J = 7.73 Hz and 1.32 Hz, 1H), 7.90 (d, J =
8.79 Hz, 2H), 7.75 (d, J = 4.92 Hz, 1H), 7.49 (t, J = 5.85 Hz,
1H), 7.33 (d, J = 2.04 Hz, 1H), 6.55–6.37 (m, 2H), 5.82 (dd, J =
8.46 Hz and 2.22 Hz, 1H), 5.56 (dd, J = 8.37 Hz and 2.19 Hz,
1H). Elemental anal. Calcd. for C28H14Br2F4IrN3O2 (%): C,
39.45; H, 1.66; N, 4.93. Found (%): C, 39.62; H, 1.69; N, 4.78.
EIMS: m/z 853 (M + 1)+.
Experimental
Materials
All manipulations involving air-sensitive reagents were per-
formed in an atmosphere of dry argon. The solvents (THF,
toluene) were purified by routine procedures and distilled
in dry argon before being used. All reagents, unless otherwise
specified, were obtained from Aldrich, Acros and TCI
Chemical Co. and used as received.
Preparation of the monomers
Iridium(III) bis[5-bromo-2-(2,4-difluorophenyl)pyridine]-
2,2,6,6-tetramethyl-3,5-heptanedione (BrFIrtmd) (5). 5 was
synthesized according to the published procedure.19 1H
NMR (300 MHz; CDCl3) d (ppm): 8.39 (d, J = 2.22 Hz,
2H), 8.10 (dd, J = 8.88 Hz and 2.28 Hz, 2H), 7.88 (dd, J =
8.79 Hz and 2.13 Hz, 2H), 6.37 (td, J = 10.97 Hz and 2.31 Hz,
2H), 5.76 (dd, J = 8.67 Hz and 2.31 Hz, 2H), 5.59 (s, 1H), 0.95
(s, 18H). Elemental anal. Calcd C33H29Br2F4IrN2O2 (%): C,
43.38; H, 3.20; N, 3.07. Found (%): C, 43.52; H, 3.11; N, 2.97.
EIMS: m/z 914 (M + 1)+.
5-Bromo-2-(2,4-difluorophenyl)pyridine (FppyBr) (1). 1 was
synthesized by the following procedure: 2,5-dibromopyridine
(10 mmol), 2,4-difluorophenylboronic acid (10 mmol) and
tetrakis(triphenylphosphine)palladium (0.1 mmol) were dis-
solved in toluene (15 ml) and ethanol (5 ml). Then an aqueous
solution of 2 M Na2CO3 (6 ml) was added to the mixture. The
resulting mixture was stirred at 100 uC for 24 h. The reaction
mixture was concentrated by evaporation of solvents and the
residue was dissolved in dichloromethane, washed with water
and dried under anhydrous sodium carbonate. After the
evaporation of solvent, the obtained product was purified by
column chromatography (silica gel) (yield: 75%). 1H NMR
(300 MHz; CDCl3) d (ppm): 8.76 (d, J = 2.28 Hz, 1H), 8.05–
7.97 (m, 1H), 7.88 (dd, J = 8.49 Hz and 2.40 Hz, 1H), 7.67
(dd, J = 8.49 Hz and 1.92 Hz, 1H), 7.01 (td, J = 8.30 Hz
and 2.49 Hz, 1H), 6.93 (td, J = 10.03 Hz and 2.49 Hz, 1H).
Elemental anal. Calcd for C11H6BrF2N (%): C, 48.97;
H,2.24; N, 5.19. Found (%): C, 49.03; H, 2.12; N, 5.04. GC-
MS (270, M+)
Iridium(III) bis[5-bromo-2-(2,4-difluorophenyl)pyridine]-
5-methyl-3-(pyridin-2-yl)-1,2,4-triazole (BrFIrptz) (6).
(FppyBr)4Ir2Cl2 (3) (0.078 mmol), Hptz (2) (0.2 mmol), and
100 mg of sodium carbonate were refluxed under inert gas
atmosphere in 2-ethoxyethanol for 16 h. After cooling to room
temperature, the colored precipitate was filtered off and was
washed with water, followed by 2 portions of ether and
hexane. The crude product was flash chromatographed using a
silica (dichloromethane : acetone = 1 : 1) column followed by
recrystallization with methanol to obtain the green powder
5-Methyl-3-(pyridin-2-yl)-4H-1,2,4-triazole (Hptz) (2)18
.
1
product after solvent evaporation and drying (yield: 67%). H
2-Cyanopyridine (50 mmol) and hydrazine monohydrate
(50 mmol) was mixed and 20 ml ethanol was added to obtain
a clear solution. After standing overnight at the room
temperature, the almost colorless crystals of 2-pyridine
carboxamidrazone could be filtered off. The product was
washed with diethyl ether and dried in air. The obtained solid
was added to a mixture of 30 ml acetic acid and acetic
anhydride (1 : 1) at 0 uC and the solution was stirred at
room temperature for 2 h. The solution was then concentrated
under vacuum and purified by repeated crystallization
from diisopropyl ether. Yield: 60%. 1H NMR (300 MHz;
CDCl3) d (ppm): 12.91 (s, 1H), 8.76 (d, J = 4.26 Hz, 1H), 8.20
(d, J = 7.92 Hz, 1H), 7.86 (td, J = 7.73 Hz and 1.65 Hz, 1H),
7.39 (t, J = 6.23 Hz, 1H), 2.54(s, 3H). Elemental anal. Calcd
for C8H8N4 (%): C, 60.00; H,5.03; N, 34.98. Found (%): C,
60.21; H, 4.89; N, 34.86. GC-MS (160, M+)
NMR (300 MHz; DMSO-d6) d (ppm): 8.23–8.12 (m, 4H), 8.08
(d, J = 4.26 Hz, 2H), 7.67 (d, J = 5.49 Hz, 1H), 7.48 (d,
J = 2.01 Hz, 1H), 7.43–7.38 (m, 2H), 6.95–6.80 (m, 2H), 5.81
(dd, J = 8.16 Hz and J = 2.31 Hz, 1H), 5.61 (dd, J= 8.64 Hz
and J = 2.34 Hz, 1H), 2.24 (s, 3H). Elemental anal. Calcd for
C30H17Br2F4IrN6 (%): C, 40.49; H,1.92; N, 9.45. Found (%):
C, 40.63; H, 1.80; N, 9.37. EIMS: m/z 890 (M + 1)+.
3,6-Dibromo-9-ethylhexylcarbazole (7), 3,6-bis(4,4,5,5-tetra-
(8)20
methyl-1,3,2-dioxaborolan-2-yl)-9-ethylhexylcarbazole
and
2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-
dioctylfluorene (9)21,22 were prepared according to the pub-
lished methods.
Preparation of the polymers
General procedures of Suzuki polycondensation, taking PCz-
FIrpic1 as an example. 3,6-Bis(4,4,5,5-tetramethyl-1,3,2-dioxa-
borolan-2-yl)-9-ethylhexylcarbazole (265.5 mg, 0.5 mmol),
3,6-dibromo-9-ethylhexylcarbazole (214 mg, 0.49 mmol),
BrIrpic (6.6 mg, 0.01 mmol) and palladium(II) acetate (2 mg)
were dissolved in a mixed solution of toluene–THF (1 : 1,
10 ml), stirred for 0.5 h, and then Et4NOH (20%) aqueous
solution (4 ml) was added. The mixture was heated to
100 uC and stirred for 42 h under argon atmosphere. Then
the polymer was capped by adding 3-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)-9-ethylhexylcarbazole (45 mg) by
Chloride-bridged dimer complex (FppyBr)4Ir2Cl2 (3) was
synthesized by the procedure reported.19
Iridium(III) bis[5-bromo-2-(2,4-difluorophenyl)pyridine]picoli-
nate (BrFIrpic) (4). (FppyBr)4Ir2Cl2 (3) (0.2 mmol) and
picolinic acid (0.5 mmol) were refluxed under an inert gas
atmosphere in dichloromethane for 24 h. After cooling to
room temperature, the reaction mixture was dissolved in
dichloromethane, washed with water and dried under anhy-
drous sodium carbonate. After the evaporation of solvent, the
This journal is ß The Royal Society of Chemistry 2007
J. Mater. Chem., 2007, 17, 2824–2831 | 2825