Synthesis of N,N,N′,N′-tetrasubstituted 1,3-bis(4-aminophenyl)azulenes and their application to a hole-injecting material in organic electroluminescent devices

Article abstract of DOI:10.1016/j.tet.2006.09.025

After a preliminary search of the reaction conditions for the Suzuki-Miyaura cross-coupling of haloazulenes with arylboronic acids, the title compounds were synthesized either by the direct coupling reaction between 1,3-dihaloazulene and the corresponding N,N-disubstituted 4-aminophenylboronic acids or by a two-step sequence involving the cross-coupling with 4-bromophenylboronic acid and subsequent Pd-catalyzed amination. Application of the title diamines to a hole-injecting material in organic electroluminescent devices was carried out to provide their prominent characteristics as a novel durable, non-cyanine and non-polyamine substance without color fade. The diamine derivatives, extended by an ethynyl unit between the azulenyl core and the 4-aminophenyl moiety, were also synthesized and found, unfortunately, unsuitable for vacuum deposition in preparing a multilayer composite.

Full text of DOI:10.1016/j.tet.2006.09.025

Tetrahedron 62 (2006) 11227–11239
Synthesis of N,N,N0,N0-tetrasubstituted 1,3-bis(4-
aminophenyl)azulenes and their application to a hole-injecting
material in organic electroluminescent devices
Nguyen Chung Thanh,a Masamichi Ikai,b, ,y Takanori Kajioka,b Hisayoshi Fujikawa,b
*
Yasunori Taga,b Yanmei Zhang,a Satoshi Ogawa,a Hiroko Shimada,a Yosuke Miyahara,a
Shigeyasu Kurodaa and Mitsunori Odac, ,z
*
aDepartment of Applied Chemistry, Faculty of Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
bToyota Central R&D Labs., Inc., Nagakute, Aichi 480-1192, Japan
cDepartment of Chemistry, Faculty of Science, Shinshu University, Asahi 3-1-1, Matsumoto, Nagano 390-8621, Japan
Received 4 July 2006; accepted 4 September 2006
Available online 5 October 2006
Abstract—After a preliminary search of the reaction conditions for the Suzuki–Miyaura cross-coupling of haloazulenes with arylboronic
acids, the title compounds were synthesized either by the direct coupling reaction between 1,3-dihaloazulene and the corresponding N,N-
disubstituted 4-aminophenylboronic acids or by a two-step sequence involving the cross-coupling with 4-bromophenylboronic acid and sub-
sequent Pd-catalyzed amination. Application of the title diamines to a hole-injecting material in organic electroluminescent devices was carried
out to provide their prominent characteristics as a novel durable, non-cyanine and non-polyamine substance without color fade. The diamine
derivatives, extended by an ethynyl unit between the azulenyl core and the 4-aminophenyl moiety, were also synthesized and found, unfortu-
nately, unsuitable for vacuum deposition in preparing a multilayer composite.
Ó 2006 Elsevier Ltd. All rights reserved.
1. Introduction
Azulene (1) constructed by two odd membered rings, an
isomer of naphthalene, appertains to a typical non-alternant
hydrocarbon (Chart 1).1 It appears blue in color because of
its relatively narrow HOMO–LUMO gap and the reduced
mutual repulsion between the unpaired electrons at the first
excited state based on the nature of the coefficients of the
HOMO and LUMO inherently accompanied with non-alter-
nant hydrocarbons,2 and the color has fascinated physical
and synthetic organic chemists for a long time.3 While azu-
lene and its derivatives were used as anti-inflammatory and
antiulcer agents extensively in the fields of medicinal chem-
istry for a long time,4 their application in material science
has been less pronounced despite their attractive color. There
is only scattered literature on their applications in material
science. There are some reports on azulene-containing poly-
mers as a conductive material5 and an amperometric
N
N
N
N
Cu
N
N
N
N
azulene, 1
CuPc, 2
Chart 1.
biosensor,6 azulene derivatives as non-linear optics7 and
near-infrared quencher.8 Independently, we have studied
the synthesis of the title azulene derivatives and applied
them to a material in organic electroluminescent (organic
EL) devices.9
Organic EL devices have received much attention in recent
years because of their application in flat and thin panel dis-
plays, overcoming the drawbacks of contemporary elec-
tronic displays.10,11 Recent interest in developing practical
EL devices for long-term use with high power-efficiency
is focused on those with a multilayered structure, which
Keywords: Azulenes; Suzuki–Miyaura reaction; Amination; Organic elec-
troluminescent device; Hole-injecting material.
* Corresponding authors. Tel./fax: +81 263 37 3343 (M.O.); tel.: +81 561
63 8493; fax: +81 561 63 6507 (M.I.); e-mail addresses: mituoda@
shinshu-u.ac.jp; m-ikai@mosk.tytlabs.co.jp
y
z
M. Ikai for the EL application.
M. Oda for the molecular design, syntheses and physical properties.
0040–4020/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2006.09.025

11228
N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
comprises hole-injecting, hole-transporting, light-emitting,
hole-blocking, and electron-injecting layers between the in-
dium-tin-oxide (ITO) electrode and the cathode. A hole-in-
jecting layer (HIL) has been used to intermediate between
the ITO electrode and a hole-transporting layer (HTL) to
demonstrate greater operational half-life time compared
with that without HIL.12 Several materials, such as copper
phthalocyanine (CuPc, 2)12c and aryl-substituted tetraami-
ne,12a,b,e were reported for this purpose. Among these,
CuPc was introduced by Kodak researchers and was a widely
used material. However, CuPc itself has strong absorption in
a visible light range so that the device containing it shows
color fade, particularly at a range of 550–700 nm, depend-
ing on the thickness. Azulene has relatively high HOMO
and low LUMO energy levels and is colored, but its extinc-
tion coefficient for visible absorption is small. Thus, we un-
dertook a design where CuPc could be replaced by an
azulene derivative with less number of amino substituents.
In this paper, we disclose the synthetic study of the cross-
coupling between haloazulenes and arylboronic acids, and
describe the full detailed synthesis of the title diamines con-
taining an azulene as a core p-electron chromophore and
their application to the HIL materials, which overcomes
this shortcoming of CuPc, as a novel non-phthalocyanine
and non-polyamine substance.
Cs2CO319 (entry 5) provided the product 9 in a good yield,
and iodide 8c under the same conditions was transformed
to 9 also in a good yield (entry 8) but not chloride 8a (entry
7). Although, we applied the Fu’s reaction conditions20 for
chloride 8a with Pd2(dba)3,21 (t-Bu)3PHBF4, and CsF, the
yield of 9 was as low as 20% (entry 9). We also examined
the reactions of 8b and c with various arylboronic acids under
the conditions of the entries 5 and 8 in Table 1. The results are
shown in Table 2. Satisfactory yields of the corresponding
aryl-substituted products were found either from 8b or c.
The yields from 8c were slightly better than those from 8b
except in the case of the 4-dibenzofurylboronic acid. With
this knowledge of the satisfactory reaction conditions
with Pd(dppf)Cl2, BINAP, and Cs2CO3 in hand, synthesis
of 1,3-diarylazulenes from 1,3-dihaloazulenes was under-
taken next.
Daub et al.
Ph
Ph
Ph
1) NBS
2) PhB(OH)2, Pd(PPh3)4
NaHCO3 aq, DME
+
1
3
4
27%
32%
Danheiser et al.
OTf
Pd(OAc)2, Cs2CO3
Ph
3
2. Results and discussion
B
PCy2
60%
2.1. Synthesis of 1-aryl-3-benzolylazulenes as prelimi-
nary experiments for the Suzuki–Miyaura cross-cou-
pling reaction of haloazulenes
5
NH2
EtO2C
CO2Et
In 1997, Daub et al. reported the first example of the Suzuki–
Miyaura cross-coupling reaction13 of bromoazulenes
(Scheme 1).14 After bromination of azulene with N-bromo-
succinimide, the products were subjected to the Suzuki–
Miyaura cross-coupling reaction with phenylboronic acid
and Pd(PPh3)4 as a catalyst to give a mixture of 1-phenyl-
and 1,3-diphenylazulenes (3 and 4) in yields of 27 and
32%, respectively. Later, Danheiser et al. found efficient
coupling with azulenyl triflate and B-phenyl-9-BBN15 and
Murafuji et al. disclosed the double cross-coupling of azule-
nylboronic acids and 1,3-dibromoazulene (6a) in better
yields than that of 4 reported by Daub et al.,16 though both
methods required expensive reagents and the manipulation
of azulene substrates and the yields were not necessarily sat-
isfactory.17 Sincewe focused on an efficient Suzuki–Miyaura
coupling of 1,3-dihaloazulenes for the synthesis of HTL
materials, we had begun with a preliminary search of the
reaction conditions for the cross-coupling between haloazu-
lenes and arylboronic acids. We chose 1-benzoyl-3-haloazu-
lenes (8) as an initial substrate to avoid any obstacles on the
process because an electron-withdrawing substituent like
a benzoyl group is known to accelerate the oxidative addition
of the palladium(0) reagent in Suzuki–Miyaura coupling.
The substrates 8a–c were prepared by halogenation of
1-benzoylazulene (7) with N-halosuccinimide (Scheme 2).
We applied various reaction conditions with Pd(PPh3)4,
Pd(PPh3)2Cl2, and Pd(dppf)Cl218 as a catalyst and phenylbo-
ronic acid for 8. The results are shown in Table 1. At first, we
used bromide 8b as a substrate (entries 1–6). The reaction
under the conditions with 8b, Pd(dppf)Cl2, BINAP, and
Murafuji et al.
Br
Pd(PPh3)2Cl2, Ba(OH)2
CO2Et
46%
7
O
Br
B
NH2
CO2Et
6a
O
CO2Et
EtO2C
NH2
Scheme 1.
X
1) PhCO2CO2Et, ZnCl2
64%
2) NXS, CHCl3
COPh
8a X = Cl; 79%
8b X = Br; 90%
8c X = I ; 94%
1
Scheme 2.
2.2. Synthesis of various 1,3-diarylazulenes including
the title azulenes
From 1,3-dibromo- and 1,3-diiodoazulenes, 6a and b, 1,3-
diarylazulenes, 4 and 11, were synthesized under the reac-
tion conditions with Pd(dppf)Cl2, BINAP, and Cs2CO3
(Table 3). In general the yields from iodide 6b are better
than those from bromide 6a except in the case of the reaction

N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
11229
Table 1. The Suzuki–Miyaura cross-coupling of 1-benzoyl-3-haloazulenes with phenylboronic acid under various conditions
X
Ph
PhB(OH)2, Pd catalyst
base, toluene
COPh
COPh
8a-c
9
Entry
X (8)
Pd catalyst and additivea
Baseb
Reaction
time (h)c
Yield of
9 (%)d
1
2
3
4
5
6
7
8
9
Br (8b)
Br (8b)
Br (8b)
Br (8b)
Br (8b)
Br (8b)
Cl (8a)
I (8c)
Pd(PPh3)4
Cs2CO3
Cs2CO3
Cs2CO3
K2CO3
Cs2CO3
K2CO3
Cs2CO3
Cs2CO3
Cs2CO3
2
1
16
30
2
2
4
2
26
55
55
74
38
87
46
40
90
20
Pd(PPh3)2Cl2, PPh3
Pd(dppf)Cl2
Pd(dppf)Cl2
Pd(dppf)Cl2, BINAP
Pd(dppf)Cl2, BINAP
Pd(dppf)Cl2, BINAP
Pd(dppf)Cl2, BINAP
Pd2(dba)3, (t-Bu)3PHBF4, CsFe
Cl (8a)
a
Pd catalyst (5 mol %) and 2 equiv of phenylboronic acid to 8 were used.
Base (4 equiv) was used.
Reaction was done in refluxing toluene.
Isolated yield after chromatographic purification.
Pd catalyst and the ligand (12 mol %), and 2 equiv of phenylboronic acid were used. The reaction was carried out at 90 ꢀC in dioxane as a solvent.
b
c
d
e
Table 2. The Suzuki–Miyaura cross-coupling of 1-benzoyl-3-haloazulenes
with various arylboronic acids under the conditions with Pd(dppf)Cl2,
BINAP, and Cs2CO3 in refluxing toluenea
Table 2. (continued)
Entry X (8)
Ar
Reaction Product Yield
time (h)
(%)b
X
Ar
ArB(OH)2, 5%Pd(dppf)Cl2
5%BINAP, Cs2CO3, toluene
8b,c
10a-g
COPh
12
13
I (8c)
1
10f
73
82
O
S
COPh
Br (8b)
1
1
10g
Entry X (8)
Ar
Reaction Product Yield
time (h)
(%)b
1
Br (8b)
3
10a
10a
10b
10b
10c
10c
10d
10d
10e
10e
10f
63
t-Bu
t-Bu
14
I (8c)
10g
83
S
a
Pd catalyst and BINAP (5 mol %), 2 equiv of arylboronic acid to 8, and
4 equiv of Cs2CO3 were used.
Isolated yield after chromatographic purification.
2
I (8c)
3
74
89
97
61
65
81
86
80
92
b
3
Br (8b)
I (8c)
3
with 4-(N,N-dimethylamino)phenylboronic acid, which re-
quired a longer reaction time (entry 8). Although some
yields of 1,3-diarylazulenes 11 from 6b (entries 2, 6, and
10) were good, other yields were relatively low. In these dou-
ble Suzuki–Miyaura reactions, thus, the second couplings
are assumed to be comparatively deactivated by the first
aryl substituents.
4
3
5
Br (8b)
I (8c)
3.5
3.5
1.5
1.5
1.5
1.5
1
Me2N
Me2N
6
We obtained the amine-substituted 1,3-diphenylazulene de-
rivatives 11c–e, all of which we had designed as primitive
hole-injecting materials. For these diamines, we also applied
a stepwise method, which involves the cross-coupling with
4-bromophenylboronic acid (12) and subsequent Pd-cata-
lyzed amination (Scheme 3). The synthetic intermediate,
1,3-bis(4-bromophenyl)azulene (11f), was prepared by the
Suzuki–Miyaura coupling under similar reaction conditions
in 18% yield from 6a or 53% yield from 6b. The amination22
of 11f using Pd(OAc)2 as a catalyst was carried out under
Fu’s reaction conditions with (t-Bu)3PHBF4 as a ligand
and t-BuONa as a base in toluene.20 In a case where volatile
dimethylamine was used, the reaction was carried out in a
sealed tube to give 72% yield of 11c. Other derivatives,
7
Br (8b)
I (8c)
8
9
Br (8b)
I (8c)
10
11
Br (8b)
86
O
(continued)

11230
N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
Table 3. The Suzuki–Miyaura cross-coupling of 1,3-dihaloazulenes with
various arylboronic acids under the conditions with Pd(dppf)Cl2, BINAP,
and Cs2CO3 in refluxing toluenea
NR2
Ar
X
C
CH
R2N
I
ArB(OH)2, 5%Pd(dppf)Cl2
5%BINAP, Cs2CO3, toluene
14a R = Me (48%)
14b R = Ph (50%)
14c NR2 = 9-carbazolyl
(72%)
13a-c
Pd(PPh3)2Cl2
PPh3, CuI, Et3N
X
Ar
4, 11a-e
6a,b
I
Entry X (6)
Ar
Reaction Product Yield of 9
time (h)
11b
(%)b
1
2
3
4
5
6
7
8
Br (6a) Ph–
I (6b) Ph–
Br (6a) 4-Ph–C6H4–
I (6b) 4-Ph–C6H4–
Br (6a) 1-Naphthyl–
I (6b) 2-Naphthyl–
Br (6a) 4-(Me2N)–C6H4– 24
I (6b) 4-(Me2N)–C6H4– 24
Br (6a) 4-(Ph2N)–C6H4–
I (6b) 4-(Ph2N)–C6H4–
Br (6a) 4-Cz–C6H4–c
I (6b)
4-Cz–C6H4–c
2
2
3
4
2
2
4
4
61
90
7
NR2
11a
11a
11b
11b
11c
11c
11d
11d
11e
11e
Scheme 4.
35
43
75
23
10
40
80
22
24
2.3. Structure and physical properties of N,N,N0,N0-
tetrasubstituted 1,3-bis(4-aminophenyl)- and 1,3-bis(4-
aminophenylethynyl)azulenes
9
2
1
2
2
10
11
12
The structures of three N,N,N0,N0-tetrasubstituted 1,3-bis(4-
aminophenyl)azulenes and three N,N,N0,N0-tetrasubstituted
1,3-bis(4-aminophenylethynyl)azulenes were characterized
by spectroscopic and combustion analyses. Signals in the
1H and 13C NMR spectra were assigned by correlations based
on their two-dimensional H–H COSY, NOESY, HMQC, and
HMBC spectra; the results are shown in Figure 1. A higher
a
Pd catalyst and BINAP (5 mol %), 3 equiv of arylboronic acid to 6, and
4 equiv of base were used.
Isolated yield after chromatographic purification.
Cz means a 9-carbazolyl group.
b
c
1
field shift of azulenyl protons in the H NMR spectra of
11c and 14a compared with those of the others may be as-
cribed to a stronger electron-donating effect of the dimethyl-
amino group. All of them were isolated as green solids and
have mainly three strong absorption bands at 230–250, 320–
350, and 370–410 nm, and a broad band at 600–700 nm.
The latter band in a visible range has small extinction coeffi-
cients of z200, which are far weaker than that of CuPc. The
results are promising for overcoming the color fade observed
in the device using CuPc (vide infra). Electrochemical oxida-
tion of 11c–e and 14a–c was examined by cyclic voltammetry
in dichloromethane containing 0.1 M tetrabutylammonium
perchlorate. The diamines 11c–e showed two oxidation po-
11d and 11e, were obtained with the corresponding amines
by conventional heating under atmosphere of argon in 85
and 75% yields, respectively. Although the two-step yields
are not attractive as compared with those of the direct
method, the amination can provide a divergent protocol for
preparing a variety of the amine derivatives from a single in-
termediate. We also prepared similar diamine derivatives,
14a–c, which are extended by an ethynyl unit between phen-
yl and the azulene moieties, by the Sonogashira reaction23 of
11b with the corresponding acetylene compounds, 13a–c, as
shown in Scheme 4.
1
tentials (Eox and Eox2) and the differences between them
Br
are more than 0.38 V, which are large enough for the purpose
of organic EL applications. The diamines 14b,c were very
sensitive to electrochemical oxidation. While diamines
14b,c provided quasi-reversible voltammograms with one ox-
idation potential,24 the diamine 14a did not show any clear
oxidation potential in its voltammogram and a significant
amount of an insoluble substance was observed at the elec-
trode surface after scans. The HOMO energy levels of these
compounds were estimated from the first oxidation potentials
(Table 4).25 Those of 11c and d are slightly less than that of
CuPc, that of 11e is the same, and those of 14b,c are slightly
greater. It should be noted that the HOMO energy levels of
11c and d intermediate between those of HTL materials,
such as TPD (5.4–5.5 eV),26 a-NPD (5.4 eV),27 TPTE
(5.3 eV),28,29 and the work function of the ITO electrode
(4.6–5.0 eV),12b and that of 11e is the same as that of
TPTE, suggesting that these compounds can be used as HIL
materials in organic EL devices (Chart 2).30 Since the diamine
derivatives, 14a–c, were found to decompose during vacuum
deposition in OLED fabrication besides possessing slightly
greater HOMO energy levels than some of the HTL materials,
onlythederivatives, 11c–e, were further examined forapplica-
tion to HIL material.
Br
B(OH)2
X
X
12
5%Pd(dppf)Cl2, 5%BINAP,
Cs2CO3, toluene
6a; X=Br
6b; X=I
11f
Br
18% from 6a
53% from 6b
NR2
HNR2, Pd(OAC)2,
11c R = Me (72%)
11d R = Ph (85%)
11e NR2 = 9-carbazolyl
(t-Bu)3PHBF4, t-BuONa
toluene
(75%)
NR2
Scheme 3.

N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
11231
8.19
7.33
(120.3)
7.04
(120.0)
(122.8)
7.47
(126.0)
7.29
(129.3)
3.00
7.58
7.19
(40.7)
N
(109.9)
N
N
(124.3)
6.91
7.21
(113.7)
7.75
(124.1)
(127.3)
7.50
7.92
7.51
(131.1)
(130.0)
(130.4)
(123.1)
(126.1)
(124.1)
7.54
7.70
7.53
8.32 (137.2)
(136.4)
8.02 (136.8)
(139.7)
8.09 (136.5)
(136.8)
(136.1)
(136.1)
(136.7)
7.25
(129.7)
7.07
(130.2)
7.03
(123.1)
8.73
8.44
8.53
(136.2)
(131.3)
(147.8)
(131.7)
(137.0)
(137.0)
(138.9)
(139.5)
(123.4)
(150.5)
N
(141.0)
N
N
(146.8)
11c
11d
11e
8.16
7.31
(120.2)
7.06
(120.4)
(123.4)
7.44
(126.1)
7.28
(129.4)
2.98
7.13
(40.3)
7.48
(124.9)
N
N
N
(109.8)
6.69
(112.0)
7.04
7.86
7.49
(122.7)
(132.9)
(132.5)
7.46
7.61
(126.9)
(132.3)
(94.2)
(84.2)
(95.0)
(82.7)
(93.6)
(85.9)
(111.4)
(110.9)
(110.5)
7.59
7.76
(142.2)
7.65
8.08 (141.1)
(141.6)
8.06 (140.8)
(141.3)
8.24 (141.7)
(140.3)
(139.7)
(139.9)
7.40
7.26
(125.3)
7.19
(124.7)
8.52
(136.9)
8.69
8.55
(126.0)
(137.2)
(137.0)
(110.8)
(116.9)
(147.6)
(122.9)
(137.3)
(149.9)
(147.3)
N
N
(140.6)
N
(123.6)
14a
14b
14c
Figure 1. Assignment of 1H and 13C chemical shifts. Carbon shifts are in parentheses.
2.4. Application of N,N,N0,N0-tetrasubstituted 1,3-bis(4-
aminophenyl)azulenes as a hole-injecting material in
organic EL devices
with the 100 nm film of CuPc was very clear. Similarly,
transmittance of visible light through the thin film (100 nm)
of 11c–e on quartz was compared with that of CuPc. While
only 20–30% of the light in the 500–800 nm range passed
through the film of CuPc, more than 80% of the light in all
of the visible range passed through the film of 11c–e. A thin-
ner film was also examined; reduction of less than 15% of
the initial light in the range through the thin film (10 nm)
of 11c–e was observed, 20–30% of the light was diminished
through that of CuPc. As expected from their visible absorp-
tion spectra, indeed color fade was not observed with the thin
film of 11c–e. Then, an application for EL devices was in-
vestigated with the multilayered structure A, which emits
green light, depicted in Figure 2. The initial characteristics,
the CIE chromatocity coordinate, EL peak, and half-life
time are shown in Table 5. There is no clear difference in
CIE chromatocity coordinate and EL peak between the HIL
materials. Although, the initial luminance with 11c–e was
slightly lower than that with CuPc, the half-life time with
11c–e was much longer than that of CuPc. While operation
with a low initial voltage retards degradation of a device in
general,12d the device with 11c unusually shows higher ini-
tial voltage and longer half-life time. Probably the relatively
greater hole drift mobility of 11c compared with those of
11d and e31 may overcome its defect. Since reduction of
Transmittance of visible light through the films of 11c–e on
quartz was first examined. Reduction of the transmittance
Table 4. Oxidation potentials and estimated HOMO energy levels of CuPc,
11c–e, and 14a–c
Compounds
E
ox 1/2 (V vs Fc/Fc+)a
HOMO (eV)b
1
Eox
2
Eox
CuPc
11c
11d
11e
14a
14b
14c
0.46
0.42
0.38
0.51
—
0.62
0.55
5.3
5.2
5.2
5.3
—
1.02
0.94
0.89
c
c
—
—
c
5.4
5.4
c
—
a
Corrected values from the Eox (V vs SCE) by subtracting the Eox value of
ferrocene (0.48 V in dichloromethane, 0.50 V in N,N-dimethylform-
amide) in the same conditions. CuPc was measured in N,N-dimethyl-
formamide and others were in dichloromethane.
HOMO energy values were obtained from oxidation potentials (Eox
against the value of ferrocene and calculated by taking the HOMO energy
value of ferrocene to be 4.8 eV with respect to zero energy level.
Eox was not clearly observed.
1
b
c
)

11232
N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
Table 5. The characteristics of the EL devices (structure A) with CuPc and
11c–e as HIL materials at 11 mA cmꢁ2
HIL Initial Initial
CIEa chromaticity EL
Half-life
N
N
N
N
materials luminance voltage
)
coordinates
peak time (h)
(nm)
(cd cmꢁ2
(eV)
x
y
11c
11d
11e
578
567
543
602
8.42
5.52
5.09
7.35
0.336
0.356
0.355
0.335
0.524 526
630
400
600
150
0.531 535
0.534 538
0.534 533
TPD
CuPc
a
ꢀ
Commission Internationale de L’Eclairage.
N
N
Table 6. The characteristics of the EL devices (structure B) with CuPc and
11c–e as HIL materials at 11 mA cmꢁ2
HIL
materials
Initial
luminance
Initial
voltage
(eV)
CIEa chromaticity
coordinates
EL
peak
(nm)
N
N
(cd cmꢁ2
)
x
y
TPTE
11c
11d
11e
444
238
299
221
9.95
10.05
6.71
0.610
0.619
0.609
0.617
0.379
0.373
0.384
0.375
620
621
614
618
CN
NC
CuPc
8.11
N
O
O
a
ꢀ
Commission Internationale de L’Eclairage.
O
N
O
Al
N
N
advancing to the development of a more practical applica-
tion, which will be reported elsewhere in due course.
Alq3
DCJTB
Chart 2. Structures of the dopant and hole-transporting and light-emitting
materials used in our study.
3. Summary
After a preliminary search of the reaction conditions for the
Suzuki–Miyaura cross-coupling of haloazulenes with vari-
ous arylboronic acids, bases, palladium catalysts, and addi-
tive ligands, the title compounds have been synthesized in
moderate yields either by the direct coupling reaction be-
tween 1,3-dihaloazulene and the corresponding N,N-disub-
stituted 4-aminophenylboronic acids under the conditions
with Pd(dppf)Cl2, BINAP, and Cs2CO3 in refluxing toluene
or by a two-step sequence involving the cross-coupling with
4-bromophenylboronic acid and subsequent Pd(OAc)2-cata-
lyzed amination with (t-Bu)3PHBF4 and t-BuONa. We have
also synthesized the derivatives extended by an ethynyl
group between the azulenyl core and the aminophenyl
group, N,N,N0,N0-tetrasubstituted 1,3-bis(4-aminophenyl-
ethynyl)azulenes 14a–c, as a candidate for HIL material.
Unfortunately, the latter derivatives were not appropriate
for a fabrication process by vacuum deposition. Application
of these title diamines, 11c–e, to HIL material in organic
electroluminescent devices was made to provide their prom-
inent characteristics as a novel durable, non-cyanine, and
non-polyamine substance without color fade.
light at a range of 500–800 nm through the thin films of
11c–e was clearly shown, we also examined another multi-
layered structure B, which emitted the orange light by using
DCJTB32 as a dopant, depicted in Figure 2. The characteris-
tics of the luminescence are shown in Table 6. Although we
have not checked the half-life time with this structure, the
device with 11c indicated the most effective performance
among them. With these results in hand, we now are
Al cathode
LiF
Alq3 (60 nm)
Structure A
TPTE (50 nm)
HIL materials
(10 nm)
ITO electrode
glass
Al cathode
LiF
Alq3 (40 nm)
4. Experimental
4.1. General
Alq3 + 1.2-1.5 wt% of
Structure B
DCJTB (40 nm)
TPTE (30 nm)
HIL materials
(10 nm)
Melting points were measured on a Yanaco MP-3 and are
uncorrected. IR spectra were recorded on a Perkin–Elmer
Spectrum RX I spectrometer. UV spectra were measured on
a Shimadzu UV-1600 spectrometer. 1H and 13C NMR were
ITO electrode
glass
Figure 2. The investigated organic EL architectures.

N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
11233
recorded with tetramethylsilane as an internal standard on a
JEOL a400 or JEOL dECP-600 NMR. Mass spectra were
measured on a JMS-700 mass spectrometer. Cyclic voltam-
mograms were recorded on a Yanako P1100 instrument.
Column chromatography was done with either Merck
Kieselgel 60 Art 7734 or Wako Activated alumina. Toluene
was purified by distillation from calcium hydride under a ni-
trogen atmosphere. Diphenylamine, dimethylamine aqueous
solution, and carbazole were purchased from Tokyo Kasei
Ind. Co., cesium carbonatewas purchased from Kanto Chem.
Inc., and BINAP (rac-2,20-bis(diphenylphosphino)-1,10-
binaphthyl), tetrakis(triphenylphosphine)palladium, bis-
(triphenylphosphine)palladium dichloride, tris(dibenzyl-
ideneacetone)dipalladium, and [1,10-bis(diphenylphosphino)-
ferrocene]dichloropalladium (1:1 complex with dichloro-
methane) were purchased from Aldrich Co. and were used
without purification. Various arylboronic acids were also
purchased from Aldrich Co., except 4-[9-(carbazolyl)]-
phenylboronic acid, which was prepared by the reported
method.33 Sodium tert-butoxide, palladium acetate, and
copper iodide were purchased from Wako Chem. Co. and
were used without purification. The ethynyl compounds
13a,34 b,35 and c36 were prepared from disubstituted 4-halo-
anilines by palladium-catalyzed Sonogashira coupling
with trimethylsilylacetylene, followed by deprotection with
K2CO3 in methanol according to their reported methods.37
1,3-Dihaloazulenes, 6a and b, were prepared from azulene
with N-iodo- and N-bromosuccinimides according to a liter-
ature procedure38 and were purified by alumina chromato-
graphy before use.
7.92 (t, J¼10.0 Hz, 1H), 7.84–7.82 (dm, J¼6.8 Hz, 2H),
7.67–7.57 (m, 3H), 7.53–7.49 (m, 2H) ppm; 13C NMR
(CDCl3) d¼191.9, 142.8, 140.8, 140.74, 140.71, 140.4,
139.6, 137.9, 131.5, 129.6, 129.5, 128.2, 127.9, 123.9,
104.6; IR (KBr) nmax¼1625s, 1594s, 1574s, 1533m, 1492s,
1456s, 1414m, 1379m, 1333m, 1285m, 1236m, 1178m,
1116m, 1072w, 1024m, 977w, 956w, 932w, 904m, 866m,
854m, 800m cmꢁ1; UV–vis (CH2Cl2) lmax¼236 (log 3¼
4.42), 244 (4.45), 274sh (4.40), 282 (4.44), 307sh (4.51),
318 (4.57), 393 (4.11), 404 (4.10), 521sh (2.64), 555
(2.72), 581sh (2.66), 662sh (2.07) nm; MS (70 eV) m/z (rel
int): 313 (M++1, 18), 312 (M+, 95), 311 (M++1, 22), 310
(M+, 100), 235 (90), 233 (91), 207 (10), 205 (11), 126
(84), 77 (19).
Compound 8c (X¼I) (94%): green solids, mp 109–111 ꢀC.
1H NMR (CDCl3) d¼9.68 (d, J¼9.8 Hz, 1H), 8.49 (d,
J¼9.8 Hz, 1H), 8.17 (s, 1H), 7.93 (t, J¼9.8 Hz, 1H), 7.84–
7.81 (dm, J¼6.8 Hz, 2H), 7.72–7.56 (m, 3H), 7.53–7.49
(m, 2H) ppm; 13C NMR (CDCl3) d¼191.9, 148.8, 144.1,
141.5, 140.7 (2C), 140.5, 138.8, 131.5, 129.9, 129.5,
128.3, 128.2, 126.3, 75.3; IR (KBr) nmax¼1654w, 1636w,
1616s, 1588w, 1573m, 1545w, 1529m, 1509w, 1491m,
1447m, 1414m, 1364m, 1329w, 1282m, 1233m, 1173w,
1129w, 1079w, 1036w, 1019m, 953w, 929w, 898m, 875w,
859s, 795w, 775m, 747s, 732w, 703m, 665m, 619w cmꢁ1
;
UV–vis (CH2Cl2) lmax¼231 (log 3¼4.53), 284 (4.50), 321
(4.58), 395 (4.15), 407 (4.15), 413 (3.97), 552 (2.90),
590sh (2.82), 638sh (2.28) nm; MS (70 eV) m/z (rel int):
358 (M+, 100), 282 (10), 281 (86), 253 (10), 202 (18), 126
(49), 77 (12). Anal. Calcd for C17H11IO: C, 57.01; H,
3.10. Found: C, 57.37; H, 3.25.
4.2. Synthesis of 1-benzoyl-3-haloazulenes (8)
To a solution of 1-benzoylazulene (2.00 mmol), prepared by
the method of Sugihara et al.,39 in 10 ml of chloroform at
0 ꢀC was added 3.00 mmol of N-halosuccinimide in several
portions. After being stirred at 40 ꢀC for 3 h, the reaction
mixture was concentrated and the residue was purified by
alumina column chromatography. Elution with chloroform–
hexane (3:7) gave 8 as solids. Analytical samples were
obtained by recrystallization from hexane–dichloromethane.
Compound 8a (X¼Cl) (79%): green solids, mp 70–72 ꢀC.
1H NMR (CDCl3) d¼9.69 (d, J¼9.8 Hz, 1H), 8.59 (d,
J¼9.8 Hz, 1H), 7.97 (s, 1H), 7.91 (t, J¼9.8 Hz, 1H), 7.84–
7.81 (dm, J¼6.8 Hz, 2H), 7.67–7.56 (m, 3H), 7.53–7.49
(m, 2H) ppm; 13C NMR (CDCl3) d¼192.0, 140.9, 140.7,
140.0, 139.9, 139.7, 138.6, 136.2, 131.4, 129.5, 129.4,
128.2, 127.9, 122.5, 116.9; IR (KBr) nmax¼1655m, 1627s,
1595s, 1576m, 1561w, 1543m, 1525w, 1508w, 1498m,
1476w, 1458m, 1449w, 1417s, 1385s, 1342m, 1288m,
1237s, 1179, 1119w, 1026w, 977w, 958w, 919w, 867w,
4.3. The Suzuki–Miyaura cross-coupling reactions
of 1-benzoyl-3-haloazulenes (8)
A mixture of 8 (0.300 mmol), Cs2CO3 (1.20 mmol), and ar-
ylboronic acid (0.600 mmol) in 10 ml of toluene was evacu-
ated well. And either 0.015 mmol of the palladium catalyst
or the same amount of both the palladium catalyst and an ad-
ditive was added to the mixture. The flask was evacuated and
refilled with argon five times. The mixture was heated at
110 ꢀC until the halogen substrate was almost consumed.
Then the resulting reaction mixture was poured into water
and extracted with ether (30 mlꢂ3). The combined organic
layer was washed with brine and dried over anhydrous
MgSO4. The solvent was removed under reduced pressure
and the residue was chromatographed on silica gel to give
the product.
Compound 9 (90%): 1-benzoyl-3-phenylazulene, dark pur-
ple microcrystals, mp 187–191 ꢀC. 1H NMR (CDCl3)
d¼9.77 (d, J¼10.0 Hz, 1H), 9.71 (d, J¼10.0 Hz, 1H), 8.17
(s, 1H), 7.90–7.84 (m, 3H), 7.66–7.47 (m, 9H), 7.34 (m,
J¼7.4 Hz, 1H) ppm; 13C NMR (CDCl3) d¼192.9, 142.2,
142.3, 141.3, 140.6, 140.3, 139.6, 137.3, 136.3, 131.2,
130.8, 129.7, 129.6, 129.1, 128.7, 128.1, 127.7, 127.0,
123.9 ppm; IR (KBr) nmax¼3050w, 3022w, 1617, 1594s,
1571s, 1524s, 1490s, 1421m, 1390m, 1365m, 1303w,
801w, 781m, 742s, 706s, 671m, 637m, 587w, 565w cmꢁ1
;
UV–vis (CH2Cl2) lmax¼242 (log 3¼4.46), 280 (4.44), 317
(4.59), 393 (4.15), 406sh (4.14), 559 (2.88), 562 (2.88),
608sh (2.74), 650 (2.30) nm; MS (70 eV) m/z (rel int): 268
(M+, 27), 267 (M+ꢁ1, 17), 266 (M+, 81), 265 (M+ꢁ1, 6),
231 (M+ꢁ1, 12), 202 (15), 191 (32), 190 (12), 189 (100),
161 (17), 126 (40). Anal. Calcd for C17H11ClO: C, 76.55;
H, 4.16. Found: C, 76.78; H, 4.30.
1236s, 1177w, 1113w, 1074w, 1018m, 910m, 894m cmꢁ1
;
Compound 8b (X¼Br) (90%): green microprizms, mp
93–96 ꢀC (lit.40 88 ꢀC). 1H NMR (CDCl3) d¼9.70 (d,
J¼10.0 Hz, 1H), 8.57 (d, J¼10.0 Hz, 1H), 8.05 (s, 1H),
UV–vis (CH2Cl2) lmax¼238 (log 3¼4.36), 256 (4.36), 296
(4.53), 316 (4.45), 407 (3.99), 515 (2.56), 556 (2.66), 600
(2.55) nm; MS (70 eV) m/z (rel int): 309 (M++1, 24), 308

11234
N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
(M+, 100), 232 (11), 231 (62), 203 (10), 202 (45), 126 (3), 77
(5). Anal. Calcd for C23H16O: C, 89.58; H, 5.23. Found: C,
89.48; H, 5.44.
Compound 10d (86%): 1-benzoyl-3-(1-naphthyl)azulene,
1
purple solids, mp 180–182 ꢀC. H NMR (CDCl3) d¼9.86
(d, J¼9.7 Hz, 1H), 8.28 (d, J¼9.7 Hz, 1H), 8.22 (s, 1H),
7.96–7.90 (m, 4H), 7.86 (t, J¼9.7 Hz, 1H), 7.69 (t,
J¼9.7 Hz, 1H), 7.66 (d, J¼8.8 Hz, 1H), 7.61–7.46 (m,
6H), 7.35–7.43 (m, 2H) ppm; 13C NMR (CDCl3) d¼192.9,
144.0, 142.5, 142.1, 141.2, 140.2, 139.6, 137.7, 134.0,
133.8, 132.9, 131.2, 129.6, 129.3, 129.0, 128.7, 128.4,
128.1, 127.9, 127.7, 126.2, 126.1, 125.9, 125.4,
123.8 ppm; UV–vis (CH2Cl2) lmax¼233 (log 3¼4.68),
247sh (4.61), 279 (4.62), 297sh (4.62), 304sh (4.67), 315
(4.71), 388sh (4.12), 405 (4.17), 514sh (2.70), 550 (2.82),
602sh (2.65) nm; IR (KBr) nmax¼3049w, 2370w, 2344w,
1621s, 1586m, 1574m, 1520m, 1425s, 1375s, 1303m,
1259m, 1236s, 1161m, 1132m, 1006m, 908m, 821s, 809s,
780m, 748s, 711m, 699m, 660m cmꢁ1; MS (70 eV) m/z
(rel int): 359 (M++1, 43), 358 (M+, 100), 281 (48), 253
(35), 252 (75), 126 (10), 105 (6), 77 (7). Anal. Calcd for
C27H18O: C, 90.47; H, 5.06. Found: C, 90.25; H, 5.33.
Compound 10a (74%): 1-benzoyl-3-(4-tert-butylphenyl)-
1
azulene, green solids, mp 155–158 ꢀC. H NMR (CDCl3)
d¼9.75 (d, J¼9.8 Hz, 1H), 8.74 (d, J¼9.8 Hz, 1H),
8.16 (s, 1H), 7.88 (d, J¼8.4 Hz, 2H), 7.85 (t,
J¼9.2 Hz, 1H), 7.62 (t, J¼9.8 Hz, 1H), 7.58–7.45 (m, 4H),
7.52 (s, 4H), 1.39 (s, 9H) ppm; 13C NMR (CDCl3)
d¼192.9, 150.0, 142.43, 142.40, 141.3, 140.6, 140.2,
139.5, 137.4, 133.4, 131.2, 130.8, 129.6, 129.4, 129.0,
128.1, 127.6, 125.7, 123.8, 34.6, 31.4 ppm; UV–vis
(CH2Cl2) lmax¼236 (log 3¼4.44), 258 (4.40), 284 (4.50),
297 (4.58), 320 (4.46), 410 (4.03), 522 (2.60), 561 (2.69),
614 (2.52) nm; IR (KBr) nmax¼3023w, 2962w, 2868w,
1619s, 1595m, 1574m, 1531m, 1501m, 1446s, 1423s,
1389s, 1368s, 1299m, 1269m, 1235s, 1187m, 1174m,
1157m, 1099m, 1018m, 913m, 872m, 840s, 802s, 745s,
699s, 639s, 571m cmꢁ1; MS (70 eV) m/z (rel int):
365 (M++1, 29), 364 (M+, 100), 350 (19), 349 (63),
287 (8), 257 (9), 228 (6), 202 (11), 105 (23), 77 (9). Anal.
Calcd for C27H24O: C, 88.97; H, 6.64. Found: C, 88.80;
H, 6.79.
Compound 10e (92%): 1-benzoyl-3-(2-naphthyl)azulene,
dark purple plates, mp 116–118 ꢀC. 1H NMR (CDCl3)
d¼9.79 (d, J¼10.0 Hz, 1H), 8.80 (d, J¼10.0 Hz, 1H), 8.27
(s, 1H), 8.02 (s, 1H), 7.96 (d, J¼8.8 Hz, 1H), 7.93–7.86
(m, 5H), 7.71 (dd, J¼8.4, 1.6 Hz, 1H), 7.65 (t, J¼10.0 Hz,
1H), 7.59–7.49 (m, 6H) ppm; 13C NMR (CDCl3) d¼192.9,
142.5, 141.3, 140.8, 140.4, 139.7, 137.4, 133.8, 133.6,
132.4, 131.3, 130.8, 129.6, 128.4, 128.2, 128.1, 127.9,
127.8, 126.4, 126.0, 124.0 ppm; UV–vis (CH2Cl2)
lmax¼229 (log 3¼4.17), 256 (3.81), 290 (4.05), 304sh
(4.02), 317 (3.99), 393sh (4.02), 398 (4.55), 409 (3.56),
516 (2.63), 518sh (2.65), 552 (2.71), 602 (2.55), 611sh
(2.59), 749 (0.752) nm; IR (KBr) nmax¼3051w, 2371w,
2343w, 1615s, 1594m, 1572m, 1524m, 1501m, 1444m,
1421s, 1393s, 1332m, 1304m, 1234s, 1203m, 1176m,
1016m, 957m, 920m, 863m, 833s, 747s, 709s, 662s, 639m,
572m cmꢁ1; MS (70 eV) m/z (rel int): 359 (M++1, 29),
358 (M+, 100), 281 (49), 253 (18), 252 (54), 126 (10), 77
(7). Anal. Calcd for C27H18O: C, 90.47; H, 5.06. Found:
C, 90.27; H, 5.27.
Compound 10b (97%): 1-benzoyl-3-(4-biphenylyl)azulene,
1
dark green needless, mp 133–136 ꢀC. H NMR (CDCl3)
d¼9.78 (d, J¼9.8 Hz, 1H), 8.77 (d, J¼9.8 Hz, 1H), 8.21
(s, 1H), 7.90 (d, J¼7.4 Hz, 2H), 7.88 (t, J¼9.8 Hz, 1H),
7.74 (d, J¼8.4 Hz, 2H), 7.62–7.69 (m, 5H), 7.46–7.60 (m,
6H), 7.38 (tm, J¼7.4 Hz, 1H) ppm; 13C NMR (CDCl3)
d¼192.9, 142.6, 142.3, 141.2, 140.7, 146.0, 140.4, 139.8,
139.6, 137.4, 135.3, 131.3, 130.3, 130.1, 129.6, 129.2,
128.9, 128.2, 127.8, 127.5, 127.4, 127.1, 124.0 ppm; UV–
vis (CH2Cl2) lmax¼237sh (log 3¼4.49), 244 (4.52), 309
(4.72), 409 (4.04), 516sh (2.58), 560 (2.65), 610sh
(2.54) nm; IR (KBr) nmax¼3054w, 3029w, 2925w, 2852w,
1618s, 1596m, 1576m, 1531w, 1509w, 1488w, 1446m,
1424s, 1388m, 1361m, 1238s, 1184w, 1159w, 1019w,
913m, 846m, 807m, 766m, 746s, 727m, 696s, 656m cmꢁ1
;
MS (70 eV) m/z (rel int): 385 (M++1, 34), 384 (M+, 100),
307 (44), 278 (19), 277 (17), 276 (20), 252 (6), 202 (10),
138 (3), 77 (7). Anal. Calcd for C29H20NO: C, 90.60; H,
5.24. Found: C, 90.52; H, 5.39.
Compound 10f (86%): 1-benzoyl-3-(4-dibenzofuryl)azu-
lene, purple plates, mp 204–205 ꢀC. 1H NMR (CDCl3)
d¼9.85 (d, J¼9.9 Hz, 1H), 8.63 (d, J¼9.9 Hz, 1H), 8.43
(s, 1H), 8.01 (d, J¼7.7 Hz, 1H), 7.99 (d, J¼7.5 Hz, 1H),
7.96 (d, J¼7.5 Hz, 2H), 7.89 (t, J¼9.9 Hz, 1H), 7.69 (t,
J¼9.9 Hz, 1H), 7.62 (d, J¼7.5 Hz, 1H), 7.56 (t, J¼7.5 Hz,
1H), 7.52–7.46 (m, 5H), 7.44 (t, J¼7.5 Hz, 1H), 7.37 (t,
J¼7.5 Hz, 1H) ppm; 13C NMR (CDCl3) d¼192.8, 156.1,
154.0, 143.6, 142.6, 141.23, 141.16, 140.3, 139.7, 137.7,
131.3, 129.8, 129.5, 128.7, 128.1, 127.8, 127.3, 124.8,
124.7, 124.3, 124.2, 123.1, 120.9, 120.8, 119.5 ppm; UV–
vis (CH2Cl2) lmax¼242 (log 3¼4.60), 252sh (4.56), 291
(4.58), 313 (4.47), 394sh (3.90), 405 (3.92), 516sh (2.49),
550 (2.57), 599sh (2.42) nm; IR (KBr) nmax¼3050w,
2369w, 2344w, 1617s, 1575m, 1525m, 1449s, 1418s,
1388s, 1366s, 1307m, 1240s, 1185s, 1128m, 1018m,
Compound 10c (65%): 1-benzoyl-3-{4-(N,N-dimethylami-
no)phenyl}azulene, brown solids, mp 146–149 ꢀC. 1H
NMR (CDCl3) d¼9.70 (d, J¼9.6 Hz, 1H), 8.68 (d,
J¼9.6 Hz, 1H), 8.12 (s, 1H), 7.88 (d, J¼6.8 Hz, 2H), 7.79
(t, J¼9.6 Hz, 1H), 7.58–7.67 (m, 7H), 6.88 (d, J¼6.8 Hz,
2H), 3.02 (s, 6H) ppm; 13C NMR (CDCl3) d¼192.3, 150.8,
142.8, 142.3, 142.1, 141.4, 140.7, 139.7, 138.4, 132.1,
131.9, 131.0, 130.2, 129.3, 129.0, 128.2, 127.2, 124.4,
113.6,
40.6 ppm;
UV–vis
(CH2Cl2)
lmax¼229
(log 3¼4.35), 248 (4.38), 300 (4.63), 322 (4.75), 423
(3.86), 578 (2.65) nm; IR (KBr) nmax¼3022w, 2886w,
2803w, 1610s, 1573m, 1540s, 1507m, 1447m, 1420s,
1388s, 1349s, 1237s, 1200m, 1161m, 1019m, 945m,
912m, 823s cmꢁ1; MS (70 eV) m/z (rel int): 352 (M++1,
39), 351 (M+, 100), 274 (11), 258 (7), 246 (7), 231 (6),
202 (28), 137 (9), 105 (8), 77 (11). Anal. Calcd for
C25H21NO: C, 85.44; H, 6.02; N, 3.99. Found: C, 85.36;
H, 6.11; N, 4.07.
940m, 840s, 814s, 748s, 710s, 651s, 611m, 563m cmꢁ1
;
MS (70 eV) m/z (rel int): 399 (M++1, 32), 398 (M+,
100), 322 (14), 321 (55), 292 (29), 265 (11), 263 (24)
237 (5), 199 (4), 161 (4), 132 (4), 105 (4), 77 (10). Anal.
Calcd for C19H18O2: C, 87.42; H, 4.55. Found: C, 87.56;
H, 4.73.

N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
11235
Compound 10g (83%): 1-benzoyl-3-(4-dibenzothienyl)azu-
Compound 11b (75%): 1,3-bis(1-naphthyl)azulene, blue
solids, mp 66–69 ꢀC. 1H NMR (DMSO-d6 at 100 ꢀC)42
d¼8.17 (s, 1H), 8.14 (d, J¼9.8 Hz, 2H), 7.90–8.05 (m,
4H), 7.78 (d, J¼8.0 Hz, 2H), 7.70 (t, J¼9.8 Hz, 1H), 7.65–
7.70 (m, 4H), 7.54 (d, J¼8.0 Hz, 2H), 7.45 (t, J¼8.0 Hz,
2H), 7.19 (t, J¼9.8 Hz, 2H) ppm; 13C NMR (DMSO-d6 at
100 ꢀC) d¼139.4, 138.7, 137.2, 135.6, 133.8, 133.2, 132.2,
128.2, 127.8, 127.3, 126.9, 125.7, 125.3, 125.0,
123.2 ppm; UV–vis (CH2Cl2) lmax¼742sh (log 3¼2.33),
662sh (2.87), 608 (2.96), 553sh (2.78), 384sh (3.37), 352sh
(3.68), 311sh (3.93), 293 (4.06), 279sh (3.99), 268 (3.97),
229 (4.32) nm; IR (KBr) nmax¼3040m, 2949m, 2923m,
2852m, 1569s, 1543m, 1524w, 1507m, 1459m, 1437m,
1379m, 1354m, 1318w, 1261m, 1230w, 1158w, 1112m,
1009m, 967w, 947w, 925w, 801s, 776s, 741s, 647m, 579w,
553w cmꢁ1; MS (70 eV) m/z (rel int): 381 (M++1, 34),
380 (M+, 100), 379 (13), 378 (9), 377 (12), 376 (13), 363
(9), 253 (6), 252 (15), 188 (7), 182 (7), 149 (3), 111 (3),
97 (3), 69 (4). Anal. Calcd for C30H20$1/3CH2Cl2: C,
89.12; H, 5.10. Found: C, 89.21; H, 5.10.43
1
lene, purple powder, mp 194–201 ꢀC. H NMR (CDCl3)
d¼9.87 (d, J¼10.0 Hz, 1H), 8.54 (d, J¼10.0 Hz, 1H), 8.41
(s, 1H), 8.21 (dm, J¼7.6 Hz, 2H), 7.95 (dm, J¼7.2 Hz,
2H), 7.91 (t, J¼10.0 Hz, 1H), 7.80 (dm, J¼8.0 Hz, 1H),
7.71 (t, J¼10.0 Hz, 1H), 7.63–7.44 (m, 8H) ppm; 13C
NMR (CDCl3) d¼192.9, 142.5, 142.4, 141.1, 140.1, 140.9,
140.5, 139.9, 139.5, 137.6, 136.2, 135.9, 131.4, 131.3,
129.7, 129.6, 128.8, 128.5, 128.2, 127.9, 126.9, 124.8,
124.5, 124.1, 122.7, 121.8, 120.5 ppm; UV–vis (CH2Cl2)
lmax¼239 (log 3¼4.66), 257sh (4.50), 282sh (4.45), 291
(4.47), 305sh (4.44), 392sh (3.90), 403 (3.92), 547 (2.65),
605sh (2.44) nm; IR (KBr) nmax¼3048w, 1617s, 1589m,
1574m, 1523m, 1509w, 1499w, 1480w, 1444s, 1420s,
1397s, 1358s, 1298m, 1241s, 1210m, 1166m, 1131m,
1099w, 1018m, 937m, 845m, 822m, 796m, 752s, 717m,
703m, 676m, 651m, 619m, 578w, 536w, 433w cmꢁ1; MS
(70 eV) m/z (rel int): 415 (M++1, 32), 414 (M+, 100), 338
(13), 337 (50), 309 (12), 308 (41), 306 (8), 276 (4), 207
(6), 169 (7), 154 (8), 77 (4). Anal. Calcd for C29H18OS: C,
84.03; H, 4.38. Found: C, 84.06; H, 4.55.
Compound 11c (23%): 1,3-bis[4-(N,N-dimethylamino)phe-
nyl]azulene, green microcrystals, mp 152–154 ꢀC. 1H
NMR (CDCl3) d¼8.44 (d, J¼9.8 Hz, 2H), 8.02 (s, 1H),
7.53 (t, J¼9.8 Hz, 1H), 7.50 (dm, J¼8.6 Hz, 4H), 7.03 (t,
J¼9.8 Hz, 2H), 6.91 (dm, J¼8.6 Hz, 4H), 3.00 (s, 12H,
CH3) ppm; 13C NMR (CDCl3) d¼150.5, 139.7, 137.0,
136.8, 136.7, 131.7, 131.1, 126.1, 123.1, 113.7, 40.7 ppm;
IR (KBr) nmax¼3021w, 2916m, 2882m, 2848m, 2798m,
1610s, 1562m, 1533s, 1502s, 1477m, 1443m, 1383m,
1353s, 1225s, 1195m, 1167m, 1125m, 1062m, 946s,
867m, 820s, 737s, 724s, 572m, 553m, 536m cmꢁ1; UV–
vis (CH2Cl2) lmax¼236 (log 3¼4.42), 279 (4.54), 312
(4.78), 384 (4.23), 657 (2.51) nm; MS (70 eV) m/z (rel
int): 366 (M+, 100), 350 (21), 183 (11). Anal. Calcd for
C26H26N2: C, 85.21; H, 7.15; N, 7.64. Found: C, 85.45; H,
7.24; N, 7.70.
4.4. The Suzuki–Miyaura cross-coupling reactions
of 1,3-dihaloazulenes (6)
To a solution of 0.500 mmol of 1,3-dihaloazulene in 10 ml of
toluene were added 1.50 mmol of arylboronic acid, 15.6 mg
(0.025 mmol) of BINAP, 20.4 mg (0.025 mmol) of
Pd(dppf)Cl2$CH2Cl2, and 489 mg (1.50 mmol) of Cs2CO3.
This flask was evacuated and refilled with argon five times.
The mixture was heated at 110 ꢀC for several hours and then
the resulting reaction mixture was poured into water and
extracted with ether (30 mlꢂ3). The combined organic layer
was washed with brine and dried over anhydrous MgSO4.
The solvent was removed under reduced pressure and the
residue was purified by chromatography to give a coupling
product.
Compound 4 (90%): 1,3-diphenylazulene, green needles, mp
Compound 11d (80%): 1,3-bis[4-(N,N-diphenylamino)phe-
nyl]azulene, green needles, mp 279–281 ꢀC. 1H NMR
(CDCl3) d¼8.53 (d, J¼10.0 Hz, 2H), 8.09 (s, 1H), 7.54 (t,
J¼10.0 Hz, 1H), 7.51 (d, J¼8.8 Hz, 4H), 7.29 (t, J¼8.0 Hz,
8H), 7.21 (d, J¼8.8 Hz, 4H), 7.19 (d J¼8.0 Hz, 8H), 7.07
(t, J¼10.0 Hz, 2H), 7.04 (t, J¼8.0 Hz, 4H) ppm; 13C NMR
(CDCl3) d¼147.8, 146.3, 138.9, 136.8, 136.5, 136.1, 131.3,
130.4, 130.2, 129.3, 124.4, 124.1, 123.1, 122.8 ppm; IR
(KBr) nmax¼3034m, 3020m, 2956m, 2924s, 2852s, 1589s,
1570m, 1561m, 1543m, 1524m, 1509m, 1491s, 1459s,
1449m, 1439m, 1421m, 1408m, 1377m, 1364m, 1314m,
1271s, 1218m, 1174m, 1153m, 1109m, 1074m, 1027m,
936w, 896w, 871w, 840m, 749s, 694s, 670m, 619m, 573w,
1
114–116 ꢀC (lit. 100–102 ꢀC;14 117–118 ꢀC41). H NMR
(CDCl3) d¼8.55 (d, J¼9.8 Hz, 2H), 8.12 (s, 1H),
7.65 (d, J¼7.2 Hz, 4H), 7.58 (t, J¼9.8 Hz, 1H), 7.51 (t,
J¼7.2 Hz, 4H), 7.37 (tm, J¼7.4 Hz, 2H), 7.12 (t, J¼9.8 Hz,
2H) ppm.
Compound 11a (35%): 1,3-bis(4-biphenylyl)azulene, green
needles, mp 243–245 ꢀC. 1H NMR (CDCl3) d¼8.62 (d,
J¼9.8 Hz, 2H), 8.21 (s, 1H), 7.72 (m, 12H), 7.61 (t,
J¼9.9 Hz, 1H), 7.49 (t, J¼7.4 Hz, 4H), 7.38 (t, J¼7.4 Hz,
2H), 7.16 (t, J¼9.8 Hz, 2H) ppm; 13C NMR (CDCl3)
d¼140.9, 139.3, 136.9, 139.1, 137.1, 136.3, 130.2, 128.8,
127.6, 127.4, 127.3, 127.1, 123.7 ppm; IR (KBr)
nmax¼3033m, 2928w, 1594m, 1578s, 1570s, 1561s, 1544s,
1525m, 1509m, 1498w, 1482s, 1459m, 1425m, 1399m,
1365m, 1224w, 1076w, 1004m, 938w, 872w, 845s, 765s,
739s, 724s, 691s, 576m, 488w, 461w cmꢁ1; UV–vis
(CH2Cl2) lmax¼228 (log 3¼4.41), 240sh (4.37), 269sh
(4.41), 315 (4.73), 388 (4.05), 483 (1.00), 571sh (1.39),
622 (1.51), 680sh (1.39), 762sh (0.81) nm; MS (70 eV)
m/z (rel int): 433 (M++1, 38), 432 (M+, 100), 430 (1), 415
(1), 352 (3), 339 (2), 326 (2), 276 (5), 252 (2), 216 (9),
202 (1), 152 (1), 77 (1). Anal. Calcd for C34H24: C, 94.35;
H, 5.72. Found: C, 94.41; H, 5.59.
548w, 528w, 511m, 497m cmꢁ1
; UV–vis (CH2Cl2)
lmax¼230 (log 3¼4.53), 244sh (4.51), 303 (4.71), 330
(4.71), 347sh (4.63), 395sh (4.63), 577sh (2.32), 636
(2.45), 698sh (2.33) nm; MS (70 eV) m/z (rel int): 614 (M+,
100), 307 (15), 167 (13). Anal. Calcd for C46H34N2$0.8H2O:
C, 87.81; H, 5.70; N, 4.45. Found: C, 87.76; H, 5.63; N, 4.40.
Compound 11e (24%): 1,3-bis[4-(9-carbazolyl)phenyl]azu-
1
lene, green needles, mp 261–263 ꢀC; H NMR (CDCl3)
d¼8.73 (d, J¼9.8 Hz, 2H), 8.32 (s, 1H), 8.19 (d,
J¼7.7 Hz), 7.92 (d, J¼8.1 Hz, 4H), 7.75 (d, J¼8.1 Hz,
4H), 7.70 (t, J¼9.8 Hz, 1H), 7.58 (d, J¼7.7 Hz, 4H), 7.47

11236
N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
(tm, J¼7.7 Hz, 4H), 7.33 (tm, J¼7.7 Hz, 4H), 7.25 (t,
J¼9.8 Hz, 2H) ppm; 13C NMR (CDCl3) d¼141.0, 139.5,
137.2, 137.0, 136.4, 136.2, 136.1, 131.0, 129.7, 127.3,
126.0, 124.1, 123.4, 120.3, 120.0, 109.9 ppm; IR (KBr)
nmax¼3036m, 1687m, 1673m, 1655m, 1638m, 1625m,
1596m, 1578m, 1561m, 1543m, 1524s, 1508s, 1499s,
1477s, 1449s, 1422s, 1377m, 1361s, 1313s, 1227s, 1169m,
1146m, 1106m, 1031m, 936m, 914m, 835s, 771w, 744s,
719s, 649m, 632m, 566m, 530m, 518m, 437m,
421m cmꢁ1; UV–vis (CH2Cl2) lmax¼242 (log 3¼4.92),
288sh (4.68), 294 (4.78), 316 (4.74), 337sh (4.49), 377
(4.05), 390sh (4.01), 407 (3.25), 462 (2.79), 584sh (2.15),
617 (2.27), 653sh (2.10) nm; MS (70 eV) m/z (rel int): 610
(M+, 100), 305 (13), 276 (12), 241 (10), 166 (12). Anal.
Calcd for C46H30N2$1.4H2O: C, 86.86; H, 5.20; N, 4.40.
Found: C, 86.99; H, 5.08; N, 4.37.
4.4 mg (15 mmol) of (t-Bu)3PHBF4, 72.1 mg (0.750 mmol)
of NaOBu-t, and 0.75 mmol of the amine. This flask was
evacuated and refilled with argon five times and then re-
fluxed at 110 ꢀC for 7 h. Then the resulting reaction mixture
was poured into water and extracted with ether (20 mlꢂ3).
The combined organic layer was washed with brine and
dried over anhydrous MgSO4. The solvent was removed un-
der reduced pressure and the residue was chromatographed
on silica gel to give the product.
4.7. Synthesis of N,N,N0,N0-tetrasubstituted 1,3-bis(4-
aminophenylethynyl)azulenes (14a–c)
To a solution of 152 mg (0.400 mmol) of 1,3-diiodoazulene
and 1.20 mmol of N,N-disubstituted 4-ethynylaniline
in 15 ml of triethylamine were added 6.7 mg (0.010 mmol)
of bis(triphenylphosphine)palladium dichloride, 11 mg
(0.040 mmol) of triphenylphosphine, and 9.1 mg (0.048 mmol)
of CuI. This flask was evacuated and refilled with argon
five times and then refluxed at 50 ꢀC for 5 h. Then the result-
ing reaction mixture was poured into water and extracted
with ether (20 mlꢂ3). The combined organic layer was
washed with brine and dried over anhydrous MgSO4. The
solvent was removed under reduced pressure and the residue
was chromatographed on silica gel to give the product.
Compound 11f (53%): 1,3-bis(4-bromophenyl)azulene,44
1
green needles, mp 192–194 ꢀC. H NMR (CDCl3) d¼8.48
(d, J¼9.8 Hz, 2H), 8.04 (s, 1H), 7.63 (d, J¼8.4 Hz, 4H),
7.62 (t, J¼9.8 Hz, 1H), 7.49 (d, J¼8.4 Hz, 2H), 7.17 (t,
J¼9.8 Hz, 2H) ppm; 13C NMR (CDCl3) d¼139.4, 136.8,
136.7, 136.2, 135.9, 131.8, 131.3, 129.3, 124.1,
120.7 ppm; IR (KBr) nmax¼3040w, 2927m, 2846m, 1573s,
1561s, 1543s, 1525s, 1509m, 1498s, 1479s, 1459m,
1449m 1438m 1429m, 1409m, 1378m, 1362m, 1322m,
1293m, 1264m, 1219s, 1175m, 1138w, 1100m, 1074s,
1007s, 936m, 877w, 831s, 810s, 736s, 719m, 693w, 671w,
656w, 639w, 619w, 601w, 574m, 537m, 507m,
492w cmꢁ1; UV–vis (CH2Cl2) lmax¼228sh (log 3¼4.24),
252 (4.33), 286sh (4.47), 304 (4.61), 324sh (4.37), 384
(3.92), 560sh (2.29), 614 (2.44), 637 (2.32), 7.49
(1.77) nm; MS (70 eV) m/z (rel int): 440 (M+, 40), 438
(M+, 100), 436 (M+, 53), 278 (14), 276 (53), 274 (12), 202
(12), 138 (11). Anal. Calcd for C22H14Br2: C, 60.31; H,
3.22. Found: C, 60.28; H, 3.34.
Compound 14a (48%): 1,3-bis{4-(dimethylamino)phenyl-
ethynyl}azulene, mp 204–206 ꢀC. 1H NMR (CDCl3)
d¼8.52 (d, J¼9.7 Hz, 2H), 8.06 (s, 1H), 7.59 (t, J¼9.7 Hz,
1H), 7.49 (d, J¼9.0 Hz, 4H), 7.19 (t, J¼9.7 Hz, 2H), 6.69
(d, J¼9.0 Hz, 4H), 2.98 (s, 12H) ppm; 13C NMR (CDCl3)
d¼149.9, 141.3, 140.8, 139.7, 136.9, 132.5, 124.7, 111.9,
111.4, 110.8, 95.0, 82.7, 40.3 ppm; IR (KBr) nmax¼3448w,
2882w, 2793w, 2182w, 1892w, 1870w, 1846w, 1831w,
1812w, 1802w, 1794w, 1774w, 1751w, 1719m, 1702m,
1686m, 1674w, 1655w, 1638m, 1607s, 1571m, 1561w,
1532s, 1499m, 1476w, 1459w, 1438s, 1408w, 1389w,
1368s, 1286m, 1231m, 1187s, 1064m, 1003w, 948m,
867w, 805s, 754w, 726s, 670w, 644w, 575w, 549m,
517m cmꢁ1; UV–vis (CH2Cl2) lmax¼250 (log 3¼4.38),
309sh (4.65), 341 (4.77), 412 (4.22), 665 (2.49) nm; MS
(70 eV) m/z (rel int): 414 (M+, 100), 262 (18). Anal. Calcd
for C30H26N2$1/3H2O: C, 85.68; H, 6.39; N, 6.66. Found:
C, 85.80; H, 6.34; N, 6.60.
4.5. Alternative synthesis of 1,3-bis[4-(N,N-dimethyl-
amino)phenyl]azulene (11c)
In a 20 ml pressure-resistant glass bottle was charged
100 mg (0.228 mmol) of 11f, 8.0 mg (36 mmol) of palla-
dium acetate, 20 mg (69 mmol) of (t-Bu)3PHBF4, 65.0 mg
(0.676 mmol) of NaOBu-t, and 5 ml of toluene. The bottle
was evacuated at ꢁ100 ꢀC and 0.255 g (5.00 mmol) of di-
methylamine, obtained from the aqueous solution by mixing
with a NaOH solution, was introduced into the bottle at the
same temperature. The resulting bottle was sealed and
heated at 110 ꢀC in an oil bath with occasional swirling
for 7 days. The resulting reaction mixture was poured into
water and extracted with ether (20 mlꢂ3). The combined or-
ganic layer was washed with brine and dried over anhydrous
MgSO4. The solvent was removed under reduced pressure
and the residue was chromatographed on neutral alumina
with a 1:1 mixture of hexane and chloroform as eluent to
give 61.0 mg (73%) of 11c as green microcrystals.
Compound 14b (50%): 1,3-bis{4-(diphenylamino)phenyl-
ethynyl}azulene, mp 152–153 ꢀC. 1H NMR (CDCl3)
d¼8.55 (d, J¼9.7 Hz, 2H), 8.08 (s, 1H), 7.65 (t, J¼9.7 Hz,
1H), 7.46 (d, J¼8.8 Hz, 4H), 7.28 (t, J¼8.0 Hz, 8H), 7.26
(t, J¼9.7 Hz, 2H), 7.13 (d, J¼8.0 Hz, 8H), 7.06 (t,
J¼8.0 Hz, 4H), 7.04 (d, J¼8.8 Hz, 4H) ppm; 13C NMR
(CDCl3) d¼147.6, 147.3, 141.6, 141.1, 139.9, 137.0,
132.3, 129.4, 125.3, 124.8, 123.4, 122.6, 116.9, 110.9,
94.2, 84.1 ppm; IR (KBr) nmax¼3448w, 3033m, 2189w,
1945w, 1924w, 1896w, 1870m, 1794w, 1774m, 1761w,
1719m, 1655m, 1638m, 1618w, 1587s, 1562w, 1543m,
1523w, 1509w, 1491s, 1459w, 1439w, 1389w, 1362w,
1315m, 1275s, 1175m, 1075w, 1028w, 893w, 861w, 834m,
4.6. Alternative synthesis of 1,3-bis[4-(N,N-diphenyl-
amino)phenyl]- and 1,3-bis[4-(9-carbazoylyl)phenyl]-
azulenes (11d and e)
752s, 728w, 695s, 646w, 618m, 575w, 511m, 475w cmꢁ1
;
UV–vis (CH2Cl2) lmax¼254 (log 3¼4.48), 310 (4.68), 370
(4.84), 412sh (4.39), 650 (2.33) nm; MS (70 eV): m/z (rel
int) 662 (M+, 100), 331 (20). Anal. Calcd for C50H34N2:
C, 90.60; H, 5.17; N, 4.23. Found: C, 90.32; H, 5.34; N, 4.04.
To a solution of 110 mg (0.250 mmol) of 11f in 7 ml of tol-
uene were added 1.7 mg (7.5 mmol) of palladium acetate,

N. C. Thanh et al. / Tetrahedron 62 (2006) 11227–11239
11237
Compound 14c (72%): 1,3-bis(4-carbazolylphenylethynyl)-
cathode were deposited on the substrate. Devices were en-
capsulated under nitrogen in a glass-to-glass epoxy sealed
package.
1
azulene, mp 214–216 ꢀC. H NMR (CDCl3) d¼8.69 (d,
J¼9.8 Hz, 2H), 8.69 (d, J¼9.8 Hz, 2H), 8.24 (s, 1H),
8.16 (dm, J¼8.3 Hz, 4H), 7.87 (dm, J¼8.3 Hz, 4H),
7.78 (t, J¼9.8 Hz, 1H), 7.62 (dm, J¼8.3 Hz, 4H), 7.58
(d, J¼8.3 Hz, 4H), 7.44 (tm, J¼8.3 Hz, 4H), 7.41 (t,
J¼9.8 Hz, 2H), 7.32 (t-like, J¼8.3 Hz, 4H) ppm; 13C
NMR (CDCl3) d¼142.2, 141.7, 140.2, 137.2, 137.2, 132.9,
126.9, 126.1, 126.0, 125.0, 123.6, 122.9, 120.4, 120.2,
110.5, 109.8, 93.6, 85.9 ppm; IR (KBr) nmax¼3048m,
3023m, 2927m, 2866m, 2193m, 1647w, 1637w, 1625m,
1598m, 1561m, 1524m, 1499s, 1477m, 1408m, 1390m, 1359s,
1334m, 1314m, 1293m, 1227s, 1182m, 1169m, 1148m,
1119m, 1104m, 1054w, 1028w, 1015m, 1003m, 929w,
914m, 883w, 825m, 772w, 746s, 722s, 669m, 658m,
624m, 574m, 565m, 537m, 491w, 459w, 445w, 435m,
421m cmꢁ1; UV–vis (CH2Cl2) lmax¼239 (log 3¼5.03),
259sh (4.81), 284sh (4.61), 294 (4.72), 331sh (4.83), 345
(4.91), 406 (4.21), 431sh (4.14), 574sh (2.51), 629 (2.27),
695sh (2.10), 781sh (1.78) nm; MS (70 eV) m/z (rel int):
658 (M+, 100), 329 (28). Anal. Calcd for C50H30N2$0.8H2O:
C, 89.21; H, 4.73; N, 4.16. Found: C, 89.17; H, 4.80; N, 3.87.
Acknowledgements
We gratefully thank Dr. Ryuta Miyatake at University of
Toyama for helpful discussion and Mr. Keita Nakajima at
University of Toyama for his technical assistance.
References and notes
1. For reviews on the azulenes, see: Gordon, M. Chem. Rev. 1952,
52, 127–200; Hafner, K. Angew. Chem. 1958, 70, 419–430;
Nozoe, T.; Asao, T. Comprehensive Organic Chemistry (Dai-
Yuki Kagaku); Kotake, M., Ed.; Asakura Shoten: Tokyo,
1959; Chapter 16, pp 439–464 and Chapter 17, pp 465–686;
Mochalin, V. B.; Porshnev, Y. N. Russ. Chem. Rev. 1977, 46,
530–547; Lloyd, D. Non-benzenoid Conjugated Carbocyclic
Compounds; Elsevier: Amsterdam, 1984; pp 352–377; Zeller,
K.-P. Houben-Weyl: Methoden der Organischen Chemie,
4th ed.; Kropf, H., Ed.; Georg Thieme: Stuttgart, 1985;
Vol. 5, pp 127–418, Part 2C.
4.8. Cyclic voltammetry
2. Michl, J.; Thulstrup, E. W. Tetrahedron 1976, 32, 205–209;
Lemal, D. M.; Goldman, G. D. J. Chem. Educ. 1988, 65,
923–925; Lui, R. S. H. J. Chem. Educ. 2002, 79, 183–185.
3. Lui, R. S. H.; Asato, A. E. J. Photochem. Photobiol., C 2003,
4, 179–194.
A standard three-electrode cell configuration was employed
using a glassy carbon disk working electrode, a Pt wire aux-
iliary electrode, and an Ag wire as an Ag/Ag+ quasi-refer-
ence electrode. The reference electrode was calibrated at
the completion of each measurement on a saturated calomel
electrode (SCE). Cyclic voltammetry was measured in a
dichloromethane solution for 11 and 14 with tetrabutyl-
ammonium perchlorate as a supporting electrolyte and
a scan rate of 0.1 Vsꢁ1 at 25 ꢀC.
4. For recent results of medicinal and biological chemistries on
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4.9. OLED fabrication
The OLED structures A and B employed in this study are
shown in the inset of Figure 2.
Structure A: organic layers were fabricated by high-vacuum
(10ꢁ7–10ꢁ6 Torr) thermal evaporation onto a glass substrate
precoated with an ITO layer with a sheet resistance of 10 U/
square. Prior to use, the ITO was degreased with solvents
and cleaned in an UV–ozone chamber before loading into
the evaporation system. A 10 nm-thick CuPc, 11c, d, or e
as the HIL, a 50 nm-thick TPTE as the HTL, a 60 nm-thick
Alq3 as the light-emitting layer, a 0.5 nm-thick LiF as the
electron-injecting layer, and a 150 nm-thick aluminum
metal as a cathode were deposited on the substrate. Devices
were encapsulated under nitrogen in a glass-to-glass epoxy
sealed package.
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Structure B: organic layers were fabricated by high-vacuum
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precoated with an ITO layer with a sheet resistance of
10 U/square. Prior to use, the ITO was degreased with sol-
vents and cleaned in an UV–ozone chamber before loading
into the evaporation system. A 10 nm-thick CuPc, 11c, d, or
e as the HIL, a 30 nm-thick TPTE as the HTL, a 40 nm-thick
Alq3 with 1.2–1.5 wt% of DCJTB as the light-emitting layer,
a 40 nm-thick Alq3 and a 0.5 nm-thick LiF as the electron-
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