Kim et al.
New Ambipolar Blue Emitting Materials Based on Amino Coumarin Derivatives with High Efficiency for OLEDs
2
. EXPERIMENTAL DETAILS
400 MHz): ꢀ = 2ꢁ35 (s, 3 H), 6.05 (s, 1 H), 6.81 (s, 1 H),
6
.87 (d, 1 H), 7.10–7.36 (m, 11 H). FT-IR (KBr): v =
2
.1. General Method
3
054, 2987, 2306, 1720, 1592, 1421, 1265, 1120, 896, 738
−
1
1H-NMR spectra were recorded on Brucker, Advance
cm . MS (MALDI-TOF) for C H NO (M = 327.38):
2
2
17
2
+
m/z = 327.10 (M ꢂ. Anal. Calcd: C, 80.71%; H, 5.24%;
5
00 and Fast atom bombardment (FAB) mass spectra
N, 4.28%. Found: C, 80.67%; H, 5.36%; N, 4.21%.
were recorded by JEOL, JMS-AX505WA, HP5890 series
II. The optical absorption spectra were obtained by HP
2.3. Synthesis of 7-Amino-4-Methylcoumarin (3)
8
453 UV-VIS-NIR spectrometer. Perkin Elmer lumines-
cence spectrometer LS50 (Xenon flash tube) was used for
photo-luminescence (PL) spectroscopy. The redox poten-
tial of the synthesized materials was measured at the
scanning rate of 100 mV/s by WBCS 3000 system, a
cyclic voltammeter (CV). Acetonitrile (AN) containing
The mixture of 3-aminophenol (2) (2.000 g, 18.327 mmol),
ethyl acetoacetate (2.12 mL, 16.494 mmol), and bismuth
chloride (0.405 g, 1.283 mmol) was stirred at 75 C for
ꢁ
1
hour, cooled down to room temperature, and filtered
to remove undissolved materials. The remaining filtrate
was evaporated to dryness under reduced pressure. The
crude product was redissolved in boiling hexane and fil-
tered off to remove some sticky materials. The clear filtrate
was evaporated to dryness and chromatographed on sil-
0
.1 M tetrabutylammonium perchlorate was used as an
electrolyte when measured. Indium tin oxide (ITO) was
used as a working electrode and saturated Ag/AgNO as
3
a reference electrode. Ferrocene was a reference com-
pound for potential calibration. EL devices were fabricated
as the following structure: ITO/2-TNATA (60 nm)/NPB
ica gel with ethylacetate/hexane (1:1) to obtain Compound
ꢁ
3
(0.608 g, 21.1%) in a pale yellow solid. Mp 119 C.
(
(
(
15 nm)/synthesized materials or DPVBi (30 nm)/Alq
30 nm)/LiF (1 nm)/Al (200 nm), where 4,4 ,4 -tris(N-
1
3
H NMR (DMSO-d , 400 MHz): ꢀ = 2ꢁ29 (s, 3 H), 5.88
6
ꢀ
ꢀꢀ
(
s, 1 H), 6.11 (s, 2 H), 6.38 (s, 1 H), 6.55 (d, 1 H),
2-naphthyl)-N-phenyl-amino)-triphenylamine (2-TNATA)
7
.38 (d, 1 H). Anal. Calcd for C H NO : C, 68.56%; H,
10 9 2
ꢀ
was used as a hole injection layer, N,N -bis(naphthalen-
1
5.18%; N, 8.00%. Found: C, 68.50%; H, 5.34%; N, 7.91%.
ꢀ
-yl)-N,N -bis(phenyl)benzidine (NPB) as a hole trans-
porting layer, the synthesized materials as emitting layers,
-hydroxyquinoline aluminum (Alq ) as an electron trans-
2
.4. Synthesis of Amino-tri(4-methylcoumarin)
8
3
(T-MC).
porting layer, lithium flu oDr ied l ei v e( Lr ei Fd )ba ys Pa nu bel li se ch ti rno gn Ti ne jce hc -n ology to: York University Libraries
IP: 206.214.2.170 On: Tue, 01 Dec 2015 02:47:06
tion layer, ITO as anode, and Al as cathode. The organic
The mixture of (3) (0.800 g, 4.571 mmol) and (1) (2.877 g,
10.057 mmol), copper powder (0.581 g, 9.143 mmol),
potassium carbonate (2.527 g, 18.286 mmol), and 18-
crown-6 (0.121 g, 0.457 mmol) in 1,2-dichlorobenzene
(40 mL) was refluxed for 4 days, cooled down to room
temperature, and then filtered to remove remaining cata-
lyst and unreacted materials. The filtrate was evaporated
to dryness under reduced pressure. The crude product was
chromatographed on silica gel with chloroform/methanol
Copyright: American Scientific Publishers
layer was vacuum deposited by using thermal evaporation
−
6
at a vacuum base pressure of 10 torr and the rate of
2
deposition being 1 Å/s to give an emitting area of 4 mm ,
and the Al layer was continuously deposited under the
same vacuum condition. The current–voltage–luminance
(I–V –L) characteristics of the fabricated EL devices were
obtained by Keithley 2400 electrometer and light intensity
was obtained by Minolta CS-1000A.
(
50:1) to give T-MC (0.237 g, 10.6%) in a yellow solid.
ꢁ
1
Mp 339 C. H NMR (CDCl , 400 MHz): ꢀ = 2ꢁ44
2
.2. Synthesis of 7-Diphenylamino-4-Methyl-Coumarin
DPA-MC).
3
(
s, 9 H), 6.23 (s, 3 H), 7.01 (s, 3 H), 7.06 (d, 3 H),
(
7
.52 (d, 3 H). FT-IR (KBr): v = 3054, 2987, 2306, 1724,
−1
To the mixture of compound (1) (0.845 g, 2.955 mmol),
coppor powder (0.375 g, 5.909 mmol), potassium
carbonate (1.633 g, 11.818 mmol), and 18-crown-6
1604, 1421, 1265, 1120, 896, 738 cm . MS (MALDI-
+
TOF) for C H NO (M = 491ꢁ48): m/z = 492ꢁ10 (M ꢂ.
3
0
21
6
Anal. Calcd: C, 73.31%; H, 4.31%; N, 2.85%. Found:
C, 73.19%; H, 4.43%; N, 2.77%.
(0.078 g, 0.296 mmol) in 1,2-dichlorobenzene (40 mL),
diphenylamine (0.500 g, 2.955 mmol) was added. The
mixture was refluxed for 4 days, cooled to room temper-
ature, and then filtered to remove remaining catalyst and
unreacted materials. The filtrate was evaporated to dry-
ness under reduced pressure. The crude product was dis-
solved in dichloromethane (10 mL), diluted with hexane
3
. RESULTS AND DISCUSSION
The preparation of compounds, DPA-MC and T-MC was
performed by following the steps as depicted in Scheme 1.
Reaction of 7-iodo-4-methyl coumarin (1)with dipheny-
lamine was carried out under a typical Ullmann reaction
condition to give DPA-MC (yield: 29.7%).
T-MC was synthesized by two-step reactions. The con-
densation reaction of 3-aminophenol (2) and ethyl ace-
(50 mL), and then filtered off. The filtrate was evaporated
1
2–14
to dryness once more. The obtained product was recrys-
tallized from hexane and chromatographed on silica gel
with dichloromethane to give DPA-MC (0.259 g, 29.7%)
Compound
ꢁ
1
in a yellow solid. Mp 145 C. H NMR (CDCl3,
toacetate was carried out by using BiCl as a catalyst to
3
J. Nanosci. Nanotechnol. 13, 8020–8024, 2013
8021