A new series of pyrenyl-based triarylamines: Syntheses, structures, optical properties, electrochemistry and electroluminescence

Article abstract of DOI:10.1039/c5ra26017e

Five dipyrenyl-based triarylamines N-p-(R)-phenyl-N,N-dipyrenyl-1-amine (R = H (2a), CH₃ (2b), OCH₃ (2c), F (2d), NO₂ (2e)) and one tripyrenyl-based triarylamine N,N-bis(7-tert-butylpyren-1-yl)-N-pyrenyl-1-amine (3py) were successfully synthesized by copper- and palladium-catalyzed coupling reactions in high yields. These compounds were structurally characterized and their photoelectric properties were analyzed by spectroscopy, electrochemical and theoretical studies. Moreover, the structures of 2b, 2c and 2d were determined by single-crystal X-ray diffraction analysis, indicating that the three compounds are all twisted paddle-like structures with a nitrogen atom as the linking center and the substituent attached to the para position of the benzene ring has an important effect on the intermolecular interactions. Compounds 2a-2d and 3py show green fluorescence emissions with excellent absolute fluorescence quantum yields in toluene (66.06-86.06%). Compound 2e displays a faint emission with a very low quantum yield because of the effect of the strong electron-withdrawing nitro group. They are thermally stable with decomposition temperatures above 355 °C. Organic light-emitting diodes incorporating the materials 2c and 2d as non-doped emitters were fabricated.

Full text of DOI:10.1039/c5ra26017e

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A new series of pyrenyl-based triarylamines:
syntheses, structures, optical properties,
Cite this: RSC Adv., 2016, 6, 9037
electrochemistry and electroluminescence†
a
a
b
a
a
Ran Zhang, Yun Zhao, Guoling Li, Daisheng Yang and Zhonghai Ni*
Five dipyrenyl-based triarylamines N-p-(R)-phenyl-N,N-dipyrenyl-1-amine (R ¼ H (2a), CH
F (2d), NO (2e)) and one tripyrenyl-based triarylamine N,N-bis(7-tert-butylpyren-1-yl)-N-pyrenyl-1-amine
3py) were successfully synthesized by copper- and palladium-catalyzed coupling reactions in high yields.
3 3
(2b), OCH (2c),
2
(
These compounds were structurally characterized and their photoelectric properties were analyzed by
spectroscopy, electrochemical and theoretical studies. Moreover, the structures of 2b, 2c and 2d were
determined by single-crystal X-ray diffraction analysis, indicating that the three compounds are all
twisted paddle-like structures with a nitrogen atom as the linking center and the substituent attached to
the para position of the benzene ring has an important effect on the intermolecular interactions.
Compounds 2a–2d and 3py show green fluorescence emissions with excellent absolute fluorescence
quantum yields in toluene (66.06–86.06%). Compound 2e displays a faint emission with a very low
quantum yield because of the effect of the strong electron-withdrawing nitro group. They are thermally
Received 6th December 2015
Accepted 13th January 2016
DOI: 10.1039/c5ra26017e
ꢀ
stable with decomposition temperatures above 355 C. Organic light-emitting diodes incorporating the
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materials 2c and 2d as non-doped emitters were fabricated.
the synthesis of new triarylamines containing polycyclic aromatic
hydrocarbons (PAHs) has become an important tendency in
Introduction
11,12
Organic light emitting diodes (OLEDs) have attracted signicant order to obtain excellent photoelectric materials.
Indeed,
13
14,15
16
attention due to their promising applications in at-panel many naphthyl-, anthryl-,
uorenyl-based triarylamines
1–3
displays and in general lighting applications. In the past with interesting properties have been developed and employed as
decade, great progress has been made to design and synthesize emitting and/or hole-transporting materials for photoelectric
excellent functional materials for high performance OLED devices. In addition, PAHs-based triarylamines as emitters
4–7
devices. Among these materials, triarylamines have been paid featuring improved charge injection and transport characteristics
17–20
much attention due to their excellent electron donating, their could effectively elevate the device performances.
Therefore,
ease in oxidation of the nitrogen center and their ability to the design and exploitation of new PAHs-based triarylamines
8
transport charge carriers with high stability. Hence, triaryl- should be paid much more attention in order to achieve prom-
amines have been widely employed as hole-transporting and/or ising functional materials.
emitting materials for efficient electroluminescent devices. As
As one of the most known polyaromatic hydrocarbons, pyrene
one of the most typical representatives, triphenylamine deriva- has been paid everlasting attention in the past one century
tives have been deeply and widely studied. Up to date, a large because of its excellent uorescence properties, high carrier
number of triphenylamine-based compounds with interesting mobility and hole-injection ability originated from its extensive
9,10
21–24
photoelectric properties have been reported. In recent years, at p-conjugated molecular structure.
For example, several
pyrene-based tetraarylethenes with interesting aggregation-
induced emission properties have been subtly designed and
a
School of Chemical Engineering and Technology, China University of Mining and
25–27
synthesized recently.
Due to the excellent luminescent prop-
Technology, Xuzhou 221116, Jiangsu Province, P. R. China. E-mail: nizhonghai@
cumt.edu.cn
erties of pyrene and the transporting properties of triarylamines,
several series of triarylamines containing pyrenyl unit have been
b
Institute for Materials Chemistry and Engineering, Kyushu University, 744 Motooka,
28–32
Nishi-Ku, Fukuoka, 819-0395, Japan
developed, which show efficient photoelectric properties.
†
Electronic supplementary information (ESI) available: CCDC numbers 1056681 However, to the best of our knowledge, the reported pyrene-based
(
2b), 1056682 (2c), 1056680 (2d). One- and two-dimensional supramolecular
triarylamines are all monopyrenyl-based triarylamines, dipyrenyl-
and tripyrenyl-based triarylamines have not been investigated,
which may exhibit good luminescence property and hole-injection
ability.
structures of 2d. PL, cyclic voltammetry and NMR spectra. Energy levels of
devices. DSC and TGA thermograms. CCDC 1056680–1056682. For ESI and
crystallographic data in CIF or other electronic format see DOI:
1
0.1039/c5ra26017e
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Based on the above considerations, a new series dipyrenyl- drawback for this method is that the palladium catalysts and
and tripyrenyl-based triarylamines N-p-(R)-phenyl-N,N-dipyrenyl- ligands involved are very expensive and not readily available.
35
1
-amine (R ¼ H (2a), CH (2b), OCH (2c), F (2d), NO (2e)) and Chan–Lam coupling also allows the formation of aryl C–N bond
3
3
2
N,N-bis(7-tert-butylpyren-1-yl)-N-pyrenyl-1-amine (3py) were via an oxidative coupling of boronic acids with N-containing
designed and synthesized by C–N coupling reactions. The nucleophilic substrates in the air at room temperature, which
incorporation of different substituents to benzene ring can tune gives it certain advantages over the Ullmann and Buchwald–
the electronic structures of the objective compounds and then Hartwig reactions. Thus, we adopted Chan–Lam coupling reac-
inuences their photoelectric properties. Herein, we report the tion to synthesize the key intermediates using 1-aminepyrene
syntheses, structures, optical properties, electrochemistry of the and p-(R)-phenylboronic acid as the precursors. Then, the inter-
new series of pyrenyl-based triarylamines and the performances mediate compounds 1a–1d were successfully obtained in
of the simple non-doped OLED devices using two representatives moderate yields. But this method has no effect on some aryl-
(
2c and 2d) as the emitting materials.
boronic acids whose para position is functionalized with strong
electron-withdrawing groups, such as nitro group. Based on the
intermediates 1a–1d, we plan to utilize the Chan–Lam coupling
to obtain the target products (2a–2d). Regrettably, the tries under
various conditions were fruitless (route 1 in Scheme 1). It is
Results and discussion
Synthesis and characterization
The synthetic procedures of the six compounds are presented in probably that the N-arylation with boronic acids just has an effect
35
Scheme 1. According to the previous reports, arylamines can be on the C–N(heteroarene) bond transformation. Fortunately, we
33
obtained by copper catalyzed Ullmann condensation and nally successfully obtained the nal products (2a–2e) in excel-
34
palladium catalyzed Buchwald–Hartwig coupling reaction. Ull- lent yields employing palladium catalyzed Buchwald–Hartwig
mann reaction needs rather high temperature and long reaction coupling reaction (route 2 and 3 in Scheme 1), furthermore, the
time with limitations on the reaction substrates. Moreover, the compound 2e was synthesized by a one-pot process. Gratifyingly,
reaction requires strictly water-free and oxygen-free conditions the tripyrenyl-based compound 3py can also be obtained through
which also limit its wide application. The palladium catalyzed the one-pot method with a medium yield.
Buchwald–Hartwig reactions can produce a more wide variety of
arylamines with relatively mild conditions and high yield. A
Photophysical properties
The absorption properties of compounds 2a–2e and 3py were
measured in dichloromethane and toluene, and the results are
listed in Table 1. The absorption spectra of the six compounds
in dichloromethane are shown in Fig. 1. The longest wavelength
absorptions at ca. 380–425 nm are attributed to the charge
transfer from amine to pyrene. The absorptions at ca. 325 nm
seem to be ascribed to pyrene localized p–p* transitions, which
32
are similar to those of monopyrenyl-based triarylamines. The
higher energy bands appearing at ca. 272–275 nm are observed
for compounds 2a–2e, which may be assigned to pyrene and
30,36
phenyl localized p–p* transitions.
For compounds 2a–2e,
the charge transfer transitions from amine to pyrene show
a fascinating trend because of the different electron-donating
abilities of the peripheral substituents attached to the phenyl
ring. Slight red-shi absorptions are observed for compounds
2b and 2c compared to that of 2a, which is due to the intro-
duction of the electron-donating groups of methyl and methoxy.
Compound 2d displays a smaller hypsochromic shi than those
of 2b and 2c and the same to that of 2a even though it contains
an electron-withdrawing uorine group. The reason for this
phenomenon might be that the uorine on the para of the
phenyl ring cannot alter the electron structure of the whole
molecule obviously. However, the compound 2e which contains
a strong electron-withdrawing nitro group has an apparent
blue-shi (Dl ¼ 11 nm) compared to that of compound 2a. It is
probably due to that the longest absorption are attributed to
a coexistence of an electron transfer from amine to nitro unit
and a charge transfer from amine to pyrene. Thus, the absorp-
tions of compounds 2a–2e in the longest wavelength are highly
dependent on the electron-donating abilities of the
Scheme 1 Procedures for the syntheses of compounds 2a–2e and
py.
3
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Table 1 Physical parameters of the compounds
a
F
ꢁ1
lmax (nm)
Fluo. emission lem (nm) (F
(%))
Stokes shi [cm
]
Com.
DCM
TOL
DCM
TOL
Film
DCM
TOL
2
2
2
2
2
3
1
a
b
c
d
e
py
py
275, 333, 407
275, 333, 411
275, 334, 413
275, 333, 407
272, 329, 396
337, 410
333, 410
334, 412
335, 416
334, 409
334, 398
337, 413
302, 402
486 (49.15)
491 (34.45)
504 (38.28)
482 (37.85)
467 (1.04)
494 (29.26)
463
459 (81.71)
467 (67.67)
480 (86.02)
460 (69.39)
444 (3.35)
469 (66.06)
446
473 (12.61)
482 (28.83)
499 (20.21)
485 (30.04)
584 (3.47)
498 (12.14)
472
3994
3964
4372
3823
3839
4147
2604
2857
3207
2711
2603
2891
275, 300, 400
a
Absolute quantum yield measured in solutions using integrating sphere.
conjugation. For the compounds 2a–2e and 3py, the emission
peaks appear in the range of 444–480 nm and systematically vary
in agreement with the absorption spectra. Compounds 2b and 2c
exhibit red-shi relative to 2a, while compounds 2d and 2e show
blue-shi ca. 4 nm and ca. 19 nm compared to that of 2a,
respectively. In short, the emission maximums show progressive
red-shi with increasing the electron-donating ability of the
substituents on the phenyl ring and blue-shi are observed when
the electron-withdrawing strength of the substituents raise. The
compounds 2a–2d and 3py in dichloromethane show bright
green emissions. While it is worth noting that 2e is almost non-
emissive because the incorporation of a strong electron-
withdrawing nitro group might lead to the occurrence of photo-
induced electron transfer from the donor to acceptor. The
effects of concentration on the emission of compounds 2a–2d
and 3py in dichloromethane were also measured (Fig. S1†). The
intensities of the emission gradually increase with the increase of
Fig. 1 Absorption spectra of the compounds 2a–2e, 3py and 1py
recorded in dichloromethane at 1 ꢂ 10 M concentration.
ꢁ5
ꢁ8
ꢁ6
the concentration from 1.0 ꢂ 10 M to 1.0 ꢂ 10 M. However,
the uorescence intensities decrease when the concentration
substituents, when the electron-donating ability increases, the
charge-transfer interaction between amine and pyrene also
increases. Furthermore, it is necessary to compare the absorp-
tions of dipyrenyl- and tripyrenyl-based compounds with the
monopyrenyl-based triarylamine N,N-diphenylpyren-1-amine
ꢁ5
increases to 10 M due to the aggregation-induced quenching
effect. Compounds 2a–2e and 3py show small Stokes' shis
ꢁ1
(
3823–4372 cm in dichloromethane), indicating less energy
loss during the relaxation process and thereby ensuring efficient
uorescence.
1py (Scheme S1†). The lmax of compounds 2a–2d and 3py shif-

ted toward long wavelength compared to that of 1py due to the
increase of conjugation. However, the compound 2e exhibits
a small blue-shi relative to that of 1py, which probably
demonstrates a presence of an electron transfer between the
amine and the electron-withdrawing nitro unit.
From the data presented in Table 3, it is evident that the
substituent on the para position of phenyl ring inuences the
energy gaps of the compounds. The relatively strong electron-
donating moieties such as methoxy group can shrink the band
gap, while the electron-withdrawing units like nitro widen the
band gap, suggesting that enhancing the amine donor to pyrene
acceptor interaction is expected to decrease the band gap.
The uorescent emission spectra of compounds 2a–2e, 3py
ꢁ
5
and 1py were recorded in dilute dichloromethane (10 M) as
shown in Fig. 2 and the relevant data are presented in Table 1.
Dipyrenyl-based triarylamines 2a–2e and tripyrenyl-based
compound 3py show a progressive red-shi compared to that
of monopyrenyl-based compound 1py due to the increase of
Fig. 2 Normalized emission spectra of the compounds 2a–2e, 3py
and 1py recorded in dichloromethane at 1 ꢂ 10 M concentration.
ꢁ5
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(from 29.26 to 49.15%), toluene (from 66.06 to 86.02%) and in
thin lms (from 12.14 to 30.04%) were determined using an
integrating sphere (Table 1). Compounds 2a–2d and 3py show
high F s in nonpolar solvents such as toluene. However, the F s
F
F
exhibit signicant reduction in polar solvents such as dichloro-
methane. It clearly states that the main energy decay channel in
compounds 2a–2d and 3py is dipolar relaxation which is note-
39
F
worthy in polar solvents. The F of 3py shows an obvious
decline in dichloromethane compared to those of 2a–2d, which
indicates that the intermolecular p–p interactions is increased
due to the increasing number of pyrene ring in the molecule. The
F s of compounds 2a–2d and 3py measured in solid lms are
F
apparently much smaller than those in dichloromethane and
toluene due to the strong intermolecular p–p interactions in
solid states. The F
F
s of compound 2e both in solutions and thin
Fig. 3 Normalized emission spectra of the compounds 2a–2e and 3py
recorded as thin films.
lm are very low, indicating that the nitro group is effectively
involved in an electron-transfer quenching of the excited state.
To better understand the effect of environments on the elec-
tronic spectroscopic of the compounds, we selected 2a–2d and
In the thin lms, compounds 2a–2c exhibit slight blue-shi in
their emission proles and bandwidth narrowing phenomenon
3py as candidates to study the absorption and emission spectra
in different polar solvents such as toluene (TOL), dichloro-
methane (DCM), tetrahydrofuran (THF), methanol (MeOH), N,N-
dimethylformamide (DMF) and acetonitrile (MeCN). The perti-
nent data are summarized in Tables S1 and S2.† The changes in
absorption and emission proles for compound 2a with different
solvent polarities are illustrated in Fig. 4. The spectra of
compounds 2b–2d and 3py in different solvent polarities are
shown in Fig. S2–S4.† In the absorption spectra, compounds 2a–
(
Fig. 3), which suggests that the polarity of the solid lms are less
than that in dichloromethane solution. On the contrary, the
emission spectra of compound 2d and 3py in thin lm state
exhibits a small bathochromic shi (3 nm and 4 nm) relative to
that in dichloromethane solution, which indicates that the two
37
compounds exhibit a very similar conformation in both states.
However, the lm emissions of 2a–2d and 3py show red-shi (14–
6 nm) compared to that in toluene solution, implying that there
2
2d and 3py are insensitive to the solvent polarity with the shi
exist p–p stacking in lm states. Particularly, the emission
spectrum of compound 2e in solid state is signicantly red-shi
by ca. 117 nm to that observed in dichloromethane. There are
probably two reasons for the enormous red-shi. The major
reason is that the incorporation of strong electron-withdrawing
nitro group increase the charge separation resulting in dipole–
below 7 nm. In the emission spectra, compounds 2a–2d and 3py
display a remarkable and positive solvatochromism, which
indicates that the excited state is more stable in polar solvent
probably due to the separation of charges in the higher energy
38
state. A decreased uorescence quantum yield and an increased
band width are also observed in the solvent of higher polarity.
Furthermore, the relationships of Stokes' shis against the
38
dipole relaxation in the excited state and another possible cause
is due to the intermolecular p–p stacking.
T
solvent parameter E (30) of the compounds 2a–2d and 3py were
F
The absolute uorescence quantum yields F s of compounds
investigated as shown in Fig. S5.†
2
a–2d and 3py recorded in solutions such as dichloromethane
Fig. 4 UV-vis absorption (left) and emission spectra (right) of the compound 2a recorded in different solvents at ꢃ10ꢁ5 concentration.
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Table 2 Summary of the crystal data of 2b, 2c and 2d
the three compounds are in a narrow range of 1.419(2)–1.442(5)
A˚ . The C–O bond length in the structure of compound 2c is
Parameter
2b
2c
2d
˚
˚
1
.372(2) A for C
–O and 1.415(3) A for Cmethyl–O. The bond
pyrenyl
˚
length of C–F in compound 2d is 1.368(5) A. The bond angles of
C–N–C in the three compounds range from 115.92(13)–
Empirical formula
C
39
H
25
N
C
39
H
25NO
38
C H24FNO
529.58
123
0.71073
Monoclinic
ꢁ1
M
r
(g mol
)
507.60
123
0.71073
Triclinic
P1ꢀ
10.979(2)
11.264(2)
12.763(3)
115.84(3)
110.99(3)
90.42(3)
1301.0(7)
2
1.296
532.0
0.074
4524
3233
363
0.0511
0.0497
0.1119
0.972
523.60
123
0.71073
Triclinic
P1ꢀ
10.920(2)
11.212(2)
12.802(3)
115.66(3)
106.77(3)
90.89(3)
1334.7(7)
2
1.303
548.0
0.077
4641
3521
372
0.0653
0.0629
0.1645
1.038
ꢀ
T/K
125.44(11) . In the three crystal structures, the two pyrenyl rings
are completely not coplanar with the phenyl ring, which are
evidenced by the dihedral angles in the range of 62.92(11)–
77.87(11) . Of course, the two pyrenyl units in the three
˚
Wavelength (A)
Crystal system
Space group
1
P2 /c
ꢀ
˚
a/A
11.218(3)
19.743(5)
13.558(4)
90
113.822(9)
90
2747.0(13)
4
1.28
1104.0
0.081
4810
2863
367
˚
compounds are also signicantly twisting with the dihedral
b/A
˚
ꢀ
ꢀ
c/A
angle in the range from 85.63(3) to 89.52(13) . The four atoms
including the central nitrogen atom and the three carbons
bonded by nitrogen atom are almost coplanar with the maximal
ꢀ
a ( )
ꢀ
b ( )
ꢀ
g ( )
3
deviation of 0.111(2) A (N1) for 2b, 0.112(2) A (N1) for 2c and
˚
˚
˚
V (A )
˚
Z
D
0.149(5) A (N1) for 2d.
ꢁ3
calc (g cm
)
There are affluent intermolecular interactions for the three
compounds as shown in their crystal packing diagrams (Fig. 6
and S6†). For compounds 2b and 2c, rstly, two independent
units of 2b and 2c are linked together by relatively strong p–p
interactions, forming dimeric supramolecular structures, in
which the two neighboring pyrenyl moieties display nearly face-
to-face pattern with the shortest intermolecular C–C distance of
3.565(2) A for 2b and 3.503(2) A for 2c, respectively. Then, these
dimers are connected by affluent C–H/p interactions, forming
three-dimensional (3D) network supramolecular structures. In
addition, there is C–H/O hydrogen bonds for compound 2c.
For compound 2d, the pyrenyl rings in the supramolecular
dimer are marginally overlap with the shortest intermolecular
F(000)
m (mm
ꢁ1
)
Unique reections
Observed reections
Parameters
R (int)
R [I > 2s(I)]
0.0916
0.0727
0.2472
1.000
wR
GOF on F
2
(all data)
˚
˚
2
Crystal structure and theoretical calculation
Suitable single crystals of compounds 2b, 2c and 2d for X-ray
crystallography were obtained by the slow evaporation of
a mixture of dichloromethane/methanol at room temperature.
However, efforts to obtain the suitable single crystals of 2a and
˚
C–C distance of 3.639(5) A, suggesting that the p–p stacking
interaction between the pyrenyl rings for compound 2d are
relatively weak compared to those of compounds 2b and 2c.
Then, these supramolecular dimers for compound 2d are linked
by C–H/p interactions, forming two-dimensional supramo-
lecular layer structures. Finally, these layers are linked together
through C–H/F hydrogen bonds, giving 3D network supra-
molecular structure.
2e were failed. The detailed information about the crystal data
for compounds 2b–2d is summarized in Table 2. Compounds
2b and 2c crystallize in the triclinic crystal system with space
ꢀ
group P1, whereas compound 2d crystallizes in the monoclinic
1
crystal system with space group P2 /c. The crystal structure
diagrams of the three compounds are shown in Fig. 5.
To deeply investigate the electronic structures of compounds
X-ray diffraction analysis shows that compounds 2b, 2c and
2a–2e, 3py and understand the absorption characteristics,
2
d are twisted paddle-like structures with nitrogen atom as the
density functional theory (DFT) calculations (B3LYP/6-31G(d,p)
basis set) were performed on compounds 2a–2e and 3py with
the Gaussian 09W soware package. The HOMO–LUMO energy
linking center as expected. Although the substituent on the para
of the phenyl is different, the structures of the three compounds
are extremely similar to each other. The bond lengths of C–N in
gaps (E cal.) were calculated and are presented in Table 3. The
g
Fig. 5 X-ray structure diagram of the compounds 2b (A), 2c (B) and 2d (C).
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Table 4 Predicted (TDDFT B3LYP/6-31G(d,p)) vertical transitions and
their assignments
Com.
labs (nm)
f
Assignment
2
2
2
2
2
3
a
446.29
0.3282
0.0962
HOMO / LUMO (96.4%)
HOMOꢁ1 / LUMO (6.7%)
HOMO / LUMO+1 (90.0%)
HOMO / LUMO+2 (63.2%)
HOMO / LUMO (96.6%)
HOMOꢁ1 / LUMO (5.7%)
HOMO / LUMO+1 (91.1%)
HOMO / LUMO+2 (74.0%)
HOMO / LUMO (96.8%)
HOMOꢁ1 / LUMO (4.5%)
HOMO / LUMO+1 (92.2%)
HOMO / LUMO+2 (79.8%)
HOMO / LUMO (96.5%)
HOMOꢁ1 / LUMO (6.5%)
HOMO / LUMO+1 (90.3%)
HOMO / LUMO+2 (74.2%)
HOMO / LUMO (97.7%)
HOMOꢁ2 / LUMO (2.4%)
HOMO / LUMO+1 (93.8%)
HOMO / LUMO+2 (79.0%)
HOMO / LUMO (97.4%)
HOMOꢁ1 / LUMO (2.3%)
HOMO / LUMO+1 (97.5%)
HOMO / LUMO+2 (85.5%)
4
21.50
56.82
3
0.0317
0.3274
0.1045
b
c
451.58
426.51
358.59
0.0283
0.3111
0.1197
461.92
433.67
362.56
0.0287
0.3308
0.0927
d
e
447.05
422.40
357.60
0.0261
0.2866
0.2564
437.07
424.30
390.51
0.0061
0.3975
0.2609
py
480.50
456.82
411.19
0.0135
prominent wavelength vertical transitions and their oscillator
strengths (f) obtained from the computations are summarized
in Table 4. Electronic distributions in the frontier molecular
orbitals of compounds 2a–2e and 3py are shown in Fig. 7.
The measured wavelength absorption peaks and energy gaps
of these compounds are smaller than the theoretically forecast
values but the changing tendencies are similar. The predicted
vertical transitions and their assignments are summarized in
Table 4, indicating that there are three prominent absorptions for
the compounds. The longest wavelength transitions are mainly
due to the electronic excitation from the HOMO to LUMO, while
the second absorptions largely result from the HOMO to
LUMO+1 electronic excitation. Electronic distributions observed
from the frontier orbitals of compounds 2a–2d are approximately
identical. However, the electronic distributions of compound 2e
with a nitro group exhibit obvious differences with those of 2a–
Fig. 6 Crystal packing diagram of 2b (A), 2c (B) and 2d (C).
2d. For compounds 2a–2d and 3py, the HOMO orbitals are
Table 3 Electrochemical and thermal properties of the compounds
a
b
c
d
c
ꢀ
ꢀ
T
g
Com.
E
ox(DE
p
) , mV
E
g
/E
g
cal. (eV)
HOMO/LUMO (eV)
HOMO/LUMO ((DFT)(eV))
T
d
/ C
/ C
2
2
2
2
2
3
a
b
c
d
e
py
0.385 (130)
0.335 (105)
0.285 (125)
0.390 (140)
0.600 (155)
0.760 (135)
2.73/3.21
2.70/3.18
2.67/3.12
2.71/3.20
2.77/3.28
2.70/3.19
ꢁ5.185/ꢁ2.455
ꢁ5.135/ꢁ2.435
ꢁ5.085/ꢁ2.415
ꢁ5.190/ꢁ2.480
ꢁ5.400/ꢁ2.730
ꢁ5.560/ꢁ2.860
ꢁ4.834/ꢁ1.626
ꢁ4.780/ꢁ1.602
ꢁ4.699/ꢁ1.579
ꢁ4.878/ꢁ1.675
ꢁ5.267/ꢁ2.086
ꢁ5.345/ꢁ2.155
377
369
370
360
355
425
ND
131
131
131
163
238
a
b
c
Measured in dry dichloromethane. All Eox data are reported relative to ferrocene.
E
g
¼ 1240/lonset
.
Obtained from the quantum chemical
d
calculation. HOMO values were deduced from the relation: HOMO ¼ Eox + 4.8. LUMO values were calculated from the relation band gap ¼
HOMO ꢁ LOMO.
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ring on the oxidation potential is apparent for compounds 2a–
2e. The electron-donating groups (OMe > Me > H) decline the
onset oxidation potential (2c < 2b < 2a), whereas the electron-
withdrawing substituents (NO2 > F > H) increase the onset
oxidation potential (2e > 2d > 2a). The highest occupied
molecular (HOMO) values were evaluated from the oxidation
potentials by comparing with the ionization potential of ferro-
cene (HOMO ¼ Eox + 4.8, where Eox is obtained by subtraction of
the half-peak potential of ferrocene (E1/2) from oxidation
potential of the compound, E1/2 ¼ +0.44 eV relative to the
calomel electrode). The HOMO values were observed to be
ꢁ
5.185, ꢁ5.135, ꢁ5.085, ꢁ5.190, ꢁ5.400, ꢁ5.560 eV for 2a, 2b,
2
c, 2d, 2e, 3py, respectively. The HOMO of compound 3py is
much lower than compounds 2a–2e due to the extension of
conjugation, which indicates that dipyrenyl-based triarylamines
possessing better hole-injection and hole-transporting abilities
than tripyrenyl-based triarylamines for simple device. The
lowest unoccupied molecular orbital (LUMO) values for the
compounds were estimated from the relation: LUMO ¼ HOMO
ꢁ
E , and the optical energy gaps (E ) are derived from the
g g
lowest energy absorption onsets in the absorption spectra. The
LUMO values of the compounds were determined to be ꢁ2.455,
ꢁ
2.435, ꢁ2.415, ꢁ2.480, ꢁ2.730, ꢁ2.860 eV for 2a, 2b, 2c, 2d, 2e,
3
py, respectively. From the absorption edge, the band gaps (E
of the compounds are 2.73, 2.70, 2.67, 2.71, 2.77, 2.70 eV for 2a,
b, 2c, 2d, 2e, 3py, respectively. The results indicate that
g
)
Fig. 7 Electronic distributions observed for the frontier orbitals for the
compounds 2a–2e and 3py.
2
different substituents in the compounds can inevitably result in
different energy states of the whole molecule.
contributed by the whole triarylamine molecules and the LUMO
orbitals are mainly distributed over the pyrenyl segments, which
indicates that the longest absorption bands realized for the 2a–2d
and 3py can be assigned to a charge transfer from amine to
pyrene. Compound 2e shows a longest vertical transition at 437
nm which is primarily composed of a HOMO to LUMO electron
transfer. The HOMO for compound 2e is mostly spread over the
triarylamine that is away from the nitro group, while the LUMO is
chiey delocalized over nitrophenyl unit, which indicates that the
longest wavelength transition at 437 nm is probably attributed to
an amine to nitrophenyl charge transfer. The LUMO+1 for
compound 2e is composed of the pyrenyl rings, which indicates
that the second transition stems from the charge transfer from
the amine to the pyrenyl units. Additionally, involving the nitro
group in the triarylamine decreases the oscillator strength of the
The glass transition temperatures (T
temperatures (T ) of the synthesized compounds were deter-
mined with DSC and TGA respectively (Fig. S8† and Table 3). The
whole compounds show high thermally stability and the T values
g
) and the decomposition
d
d
corresponding to 5% weight loss under nitrogen atmosphere are
ꢀ
in the range of 355–425 C. The thermal property of 3py is
improved than the dipyrenyl-based compounds 2a–2e which may
due to the increased molecular weights. DSC thermograms of
compounds 2b–2e and 3py exhibit noticeable T
range of 131–238 C. Compound 2a does not show obvious T
g
peaks in the
ꢀ
g
most likely due to its crystallinity and smaller heat capacity.
Electroluminescence
Compounds 2c and 2d as two representatives were used as the
non-doped emitting layers (EMLs) in OLEDs with the following
structure: ITO/PEDOT:PSS (40 nm)/EML (30 nm, 55 nm, 80 nm,
rst absorption with a concomitant increment in the second
absorption, which indicates that the charge transfer from amine
to pyrenyl units is competitive with that from amine to nitro-
phenyl moiety.
105 nm)/TmPyPB (50 nm)/LiF (1 nm)/Al (100 nm). Among
which, poly(3,4-ethylenedioxythiophene):ploy(4-styrenesul-
fonate) (PEDOT:PSS) acts as the hole injection layer, 1,3,5-tri[(3-
pyridyl)-phen-3-yl]benzene (TmPyPB) is used as an electron-
Electrochemical and thermal studies
The electrochemical properties of compounds 2a–2e and 3py transporting material, 2c and 2d are green emitters. The struc-
were studied by cyclic voltammetry (CV) measurements and the tures and the energy levels of compounds 2c and 2d used in these
oxidation potentials of these compounds were calculated by devices are shown in Fig. S9† and the essential performance
calibrating with the internal ferrocene standard (Fig. S7†). The parameters are demonstrated in Table 5. The results suggest that
relevant parameters are collected in Table 3. Compounds 2a–2e the hole injection into the emitting layers of devices 2c and 2d is
and 3py display one quasi-reversible oxidation wave at relatively efficient because of the extremely small barrier between the hole
low oxidation potential arising from the oxidation of the amine. injection material (ꢁ5.2 eV for PEDOT:PSS) and the emitting
The inuence of the substituent at the para position of phenyl material (ꢁ5.09 eV for 2c and ꢁ5.19 eV for 2d).
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Table 5 Device characteristics of the fabricated OLED devices
a
on
b
max
c
d
e
f
Device
Structure
V
l
L
max
h
EQE
CIE
I
II
ITO/PEDOT:PSS/2c (30 nm)/TmPyPB/LiF/Al
ITO/PEDOT:PSS/2c (55 nm)/TmPyPB/LiF/Al
ITO/PEDOT:PSS/2c (80 nm)/TmPyPB/LiF/Al
ITO/PEDOT:PSS/2c (105 nm)/TmPyPB/LiF/Al
ITO/PEDOT:PSS/2d (30 nm)/TmPyPB/LiF/Al
ITO/PEDOT:PSS/2d (55 nm)/TmPyPB/LiF/Al
ITO/PEDOT:PSS/2d (80 nm)/TmPyPB/LiF/Al
ITO/PEDOT:PSS/2d (105 nm)/TmPyPB/LiF/Al
2.8
2.9
2.9
3.6
3.6
4.5
6.2
8.1
508
514
509
499
483
482
481
470
4713
3778
2871
953
3429
1283
228
2.47
5.41
2.06
1.94
1.45
1.55
0.96
0.13
0.84
1.12
0.60
0.78
0.29
0.04
0.48
0.06
0.24, 0.60
0.26, 0.60
0.28, 0.57
0.23, 0.56
0.14, 0.35
0.16, 0.35
0.17, 0.36
0.29, 0.36
III
IV
V
VI
VII
VIII
167
a
ꢁ2
b
c
ꢁ2
d
Turn-on voltage (V) at a luminance of 1 cd m
.
Emission maximum. Maximum luminance (cd m ) at the applied voltage (V). Luminance
ꢁ1
e
f
efficiency (cd A ). External quantum efficiency (%). CIE coordinates (x, y).
Fig. 8 The current density–voltage–luminance curves with varying thickness of the compounds 2c (left) and 2d (right).
The current density–voltage–luminance (I–V–L) characteris- a turn-on voltage of 3.6 V. The turn-on voltages are very low due
tics of the OLED devices are shown in Fig. 8. The performance of to the small hole-injection barrier, indicating decent device
ꢁ
1
the devices is related to the thickness of the emitters. When the performance. The maximum efficiencies of 5.41 cd A for 2c
ꢁ
1
thicknesses of emitters are 30 nm, the device I based on and 1.55 cd A for 2d are obtained from the devices II and VI
compound 2c exhibits a maximum luminance (Lmax) of 4713 cd when the thicknesses of the emitters are 55 nm.
ꢁ2
m
, an external quantum efficiency (EQE) of 0.84% and a turn-
The electroluminescent (EL) spectra of devices 2c and 2d
on voltage of 2.8 V, and the performance of device V based on 2d with different thicknesses are given in Fig. 9. When thicknesses
ꢁ2
is less efficient with a Lmax of 3429 cd m , a EQE of 0.29% and of emitters are 30, 55 and 80 nm, the maximum EL emission
Fig. 9 The electroluminescent spectrum with varying thickness of the compounds 2c (left) and 2d (right).
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peaks all locate at 507 nm for 2c, which are slightly red-shi optimized using density functional theory (DFT) at the B3LYP/6-
compared with the PL spectrum probably due to the micro- 31G(d,p) level, as implemented in Gaussian 09W soware
40
42
cavity effect. While the maximum EL peaks at 483 nm for 2d, package. The electronic transitions were calculated using the
which are matched with the PL spectrum. No emission shoul- time-dependent DFT (B3LYP) theory and the 6-31G(d,p) basis
ders at a longer wavelength due to excimer and exciplex species sets.
formed at the interface of the EML and TmPyPB layers are
detected.
OLED fabrication and performance evaluation
Poly(ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)
Experimental
(Baytron PAI 4083) and TmPyPB were purchased from
Heraeus Precious Metals GmbH Co. KG and Luminescence
Technology Corp., respectively. The OLEDs have a structure of
indium tin oxide (ITO)/PEDOT:PSS (40 nm)/2c or 2d (30 nm,
Materials and methods
Dichloromethane was distilled from calcium hydride. The 4 A˚
molecular sieves were activated before use. All other chemicals
were purchased from commercial sources and used without
5
5 nm, 80 nm, 105 nm)/TmPyPB (50 nm)/LiF (1 nm)/Al (150
43
nm). For the device fabrication, a 40 nm-thick PEDOT:PSS
layer was spin-coated from an aqueous dispersion of
PEDOT:PSS onto the onto the pre-cleaned ITO substrate and
1
13
further purication. H and C NMR spectra were collected on
a Bruker-400 MHz or Bruker-600 MHz spectrometer in CDCl or
3
DMSO solutions with TMS as an internal standard. Mass spectra
were obtained on a Bruker Ultraextreme MALDI TOF/TOF mass
spectrometer or an IonSpec HiRes MALDI FT mass spectrometer.
Elemental analysis (C, H, N) of the dried solid samples were
carried out using an Elementary Vario El analyzer. UV-vis spectra
were recorded on Shimadzu UV-3600 with a UV-VIS-NIR spec-
trophotometer. Emission spectra were performed by a HITACHI
ꢀ
then annealed at 120 C for 30 min in air condition. Subse-
quently, the EML was spin-coated with four different thick-
nesses from its fresh tetrahydrofuran solution at a spin speed of
ꢀ
1
800 rpm and then annealed at 100 C for 30 min. to remove the
2
residual solvent at N atmosphere in a glove box. Finally, the
structure of TmPyPB (50 nm)/LiF (1 nm)/Al (150 nm) was ther-
mally deposited in sequence in a vacuum chamber at a pressure
uorescence spectrometer (F-4600). The absolute uorescence
ꢁ4
less than 4 ꢂ 10 Pa through a shadow mask with an array of
quantum yields (F ) were determined by FM-4P-TCSPC Transient
F
2
1
4 mm openings. The current density–voltage–luminance (I–V–
State Fluorescence Spectrometer using an integrating sphere for
dilute solutions (dichloromethane and toluene) and thin lms
which obtained by drop-casting on quartz plate. Cyclic voltam-
metry experiments were performed with a CHI660A electro-
chemical work station. All measurements were carried out at
room temperature with a conventional three-electrode congu-
ration consisting of a glassy carbon working electrode, a plat-
inum auxiliary electrode and a calomel reference electrode. The
solvent in all experiments was dry dichloromethane and the
supporting electrolyte was 0.1 M tetrabutylammonium hexa-
L) characteristics were measured using a Keithley source
measurement unit (Keithley 2400) with a calibrated silicon
photodiode. The EL spectra of the devices were measured using
a SpectraScan PR650 spectrophotometer. All measurements
were carried out at room temperature under ambient condi-
tions. External quantum efficiency (EQE) of the devices were
calculated from the luminance, current density and EL spectra,
assuming a Lambertian distribution.
Synthetic procedures
uorophosphate. The solutions were purged with nitrogen for 5
min prior to the measurement. All scans were performed at
General procedure for synthesis of N-(p-(R)-phenyl)pyrene-1-
ꢁ1
a
a scan rate 0.05 V s . The E1/2 values were determined as 1/2 (E + amine (1a–1d). A suspension of p-(R)-phenylboric acid (8.2
p
c
p
a
p
c
p
˚
E ), where E and E are the anodic and cathodic peak potentials, mmol), Cu(OAc) $H O (80.0 mg, 0.40 mmol), and powdered 4 A
2
2
respectively. All potentials reported are referenced to ferrocene molecular sieves (3.0 g) in dry dichloromethane (50.0 mL) was
which was used as internal standard toward the end of each stirred for 5 min at room temperature. To this stirring suspen-
experiment. The glass-transition temperatures (T ) of the sion was added 1-aminopyrene (0.87 g, 4.0 mmol) and triethyl-
g
compounds were determined with differential scanning calo- amine (0.81 g, 8.0 mmol). The reaction mixture was then stirred
rimetry (DSC) under a nitrogen atmosphere by using a DSC6000 under a dry atmosphere. Following a period of 24 h, the crude
ꢀ
(
1
PerkinElmer). Samples were heated to 300 or 400 C at a rate of reaction mixture was ltered through a plug of celite to remove
ꢀ
ꢁ1
ꢀ
ꢁ1
0 C min and cooled at 10 C min then heated again under the molecular sieves and any insoluble by-products and then the
the same heating conditions as used in the initial heating ltrate was concentrated to afford the crude product mixture. The
process. Decomposition temperature (T ) were determined with products (1a–1d) were isolated by silica gel column chromatog-
d
thermogravimetric analysis (TGA) under a nitrogen atmosphere raphy using hexane/dichloromethane mixture as the eluent.
ꢀ
by using a DTG-60AH (Shimadzu). Samples were heated to 800 C
A similar procedure with phenylboronic acid, p-methyl-
ꢀ
ꢁ1
at a rate of 10 C min . Crystals data of compounds were phenylboronic acid, p-methoxyphenylboronic acid and p-uo-
selected on a Bruker APEX II CCDC diffractometer with graphite- rophenylboronic acid was followed for the synthesis of 1a–1d.
˚
monochromated Mo-Ka radiation (l ¼ 0.71073 A) at 123 K using
N-Phenylpyrene-1-amine (1a) was obtained as a white
the u-scan technique. The structures were solved by direct powder solid (silica gel column chromatography from hexane/
methods with the SHELXS-97 (ref. 41) computer program, and dichloromethane mixture, 3 : 2). Yield: 0.88 g, 75%. Mp: 143–
rened by full-matrix least-squares methods (SHELXL-97) on F . 146 C. H-NMR (400 MHz, d
2
ꢀ
1
6
-DMSO) d (ppm): 8.70 (s, 1H), 8.39
The ground state geometries of all molecules were fully (d, J ¼ 9.2 Hz, 1H), 8.24–7.95 (m, 8H), 7.28 (t, J ¼ 7.8 Hz, 2H),
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1
3
7
.18 (d, J ¼ 8.0 Hz, 2H), 6.89 (t, J ¼ 7.3 Hz, 1H). C-NMR (101 (400 MHz, CDCl
3
) d (ppm): 8.36 (d, J ¼ 9.2 Hz, 2H), 8.10–8.01 (m,
MHz, d -DMSO) d (ppm): 145.19 (s), 138.42 (s), 131.88 (s), 131.58 16H), 7.94 (s, 2H), 7.02–6.86 (s, 3H). MALDI TOF-MS: m/z
6
+
(
1
1
s), 129.68 (s), 127.90 (s), 126.75 (s), 126.38 (d, J ¼ 10.7 Hz), 493.189 [M] . Elemental analysis: anal. calcd for C H N: C,
3
8
23
25.95 (d, J ¼ 6.7 Hz), 125.13 (s), 124.98 (s), 124.77 (s), 122.87 (s), 92.46; H, 4.70; N, 2.84. Found: C, 94.24; H, 4.82; N, 2.64%.
21.93 (s), 120.49 (s), 117.64 (d, J ¼ 21.9 Hz). Elemental analysis:
N-p-(Methyl)-phenyl-N,N-dipyrenyl-1-amine (2b) was ob-
anal. calcd for C22
H
15N: C, 90.07; H, 5.15; N, 4.77. Found: C, tained as yellow-green crystals. Yield: 0.81 g, 80%. Mp: 263–265
+
ꢀ
1
91.02; H, 5.13; N, 4.70%. GC/MSD: m/z 293 [M] .
C. H-NMR (400 MHz, CDCl
3
) d (ppm): 8.36 (d, J ¼ 9.2 Hz, 2H),
N-(p-Methylphenyl)pyrene-1-amine (1b) was obtained as 8.18 (d, J ¼ 7.6 Hz, 2H), 8.05 (m, 10H), 7.91 (d, J ¼ 9.2 Hz, 2H),
ꢀ
faint yellow plate crystals. Yield: 0.80 g, 66%. Mp: 168–169 C. 7.79 (d, J ¼ 8.4 Hz, 2H), 6.99 (d, J ¼ 8.4 Hz, 2H), 6.79 (d, J ¼ 8.4
1
13
H-NMR (400 MHz, d -DMSO) d (ppm): 8.60 (s, 1H), 8.41 (d, J ¼ Hz, 2H), 2.31 (s, 3H). C-NMR (101 MHz, CDCl ) d (ppm):
6
3
9
2
1
(
(
.2 Hz, 1H), 8.15–8.08 (m, 4H), 8.03–7.86 (m, 4H), 7.12 (s, 4H), 148.78 (s), 142.95 (s), 131.43 (s), 131.13 (s), 130.58 (s), 129.77 (s),
1
3
.27 (s, 3H). C-NMR (101 MHz, d -DMSO) d (ppm): 142.17 (s), 128.78 (s), 127.63 (s), 127.31 (s), 126.67 (d, J ¼ 10.1 Hz), 126.44
6
39.33 (s), 131.84 (d, J ¼ 33.4 Hz), 130.15 (s), 129.85 (s), 127.94 (s), 126.10 (d, J ¼ 12.3 Hz), 125.76 (s), 125.05–124.93 (m), 123.58
s), 126.69 (s), 126.39 (s), 126.17 (s), 125.99 (s), 125.32 (s), 125.09 (s), 120.92 (s), 58.49 (s), 29.71 (s), 20.70 (s). MALDI TOF-MS: m/z
+
s), 124.63 (d, J ¼ 12.3 Hz), 124.17 (s), 122.80 (s), 120.92 (s), 507.213 [M] . Elemental analysis: anal. calcd for C39
H25N: C,
1
18.69 (s), 116.38 (s), 20.84 (s). Elemental analysis: anal. calcd 92.28; H, 4.96; N, 2.76. Found: C, 90.45; H, 4.82; N, 2.98%.
for C23
H
17N: C, 89.87; H, 5.57; N, 4.56. Found: C, 89.85; H, 5.54;
N-p-(Methoxy)-phenyl-N,N-dipyrenyl-1-amine (2c) was ob-
+
N, 4.61%. GC/MSD: m/z 307 [M] .
tained as yellow-green bulk crystals. Yield: 0.87 g, 83%. Mp:
ꢀ
1
N-(p-Methoxyphenyl)pyrene-1-amine (1c) was obtained as 257–259 C. H-NMR (400 MHz, CDCl ) d (ppm): 8.35 (d, J ¼ 9.6
3
ꢀ
1
green plate crystals. Yield: 0.76 g, 59%. Mp: 164–166 C. H- Hz, 2H), 8.18 (t, J ¼ 7.6 Hz, 2H), 8.11–7.97 (m, 7.6 Hz, 10H), 7.89
NMR (400 MHz, d
-DMSO) d (ppm): 8.53 (s, 1H), 8.46 (d, J ¼ (d, J ¼ 9.2 Hz, 2H), 7.73 (d, J ¼ 8.4 Hz, 2H), 6.89 (d, J ¼ 9.2 Hz,
.2 Hz, 1H), 8.12–8.06 (m, 4H), 7.98–7.94 (m, 2H), 7.87 (d, J ¼ 8.8 2H), 6.77 (d, J ¼ 8.8 Hz, 2H), 3.79 (s, 3H). C-NMR (101 MHz,
Hz, 1H), 7.72 (d, J ¼ 8.4 Hz, 1H), 7.23 (d, J ¼ 8.8 Hz, 2H), 6.95 (d, CDCl ) d (ppm): 154.63 (s), 143.44 (s), 131.14 (s), 128.57 (s),
-DMSO) 127.42 (d, J ¼ 20.1 Hz), 126.49 (s), 126.16 (s), 125.68 (d, J ¼ 8.7
d (ppm): 154.96 (s), 140.69 (s), 137.15 (s), 131.98 (d, J ¼ 37.6 Hz), Hz), 124.94 (d, J ¼ 12.2 Hz), 123.56 (s), 122.10 (s), 114.60 (s),
6
1
3
9
3
1
3
J ¼ 8.8 Hz, 2H), 3.76 (s, 3H). C-NMR (101 MHz, d
6
+
1
27.99 (s), 126.61 (d, J ¼ 4.5 Hz), 125.99 (d, J ¼ 17.6 Hz), 125.24 55.48 (s). MALDI TOF-MS: m/z 523.124 [M] . Elemental analysis:
(
(
s), 124.47–123.89 (m), 122.58 (s), 121.93 (s), 119.53 (s), 115.18 anal. calcd for C H NO: C, 89.46; H, 4.81; N, 2.68. Found: C,
s), 114.40 (s), 55.74 (s). Elemental analysis: anal. calcd for 91.25; H, 4.62; N, 2.81%.
17NO: C, 85.42; H, 5.30; N, 4.33; O, 4.95. Found: C, 85.34; H, N-p-(Fluoro)-phenyl-N,N-dipyrenyl-1-amine (2d) was obtained
3
9
25
23
C H
+
ꢀ
1
5
.35; N, 4.93%. GC/MSD: m/z 323 [M] .
N-(p-Fluorophenyl)pyrene-1-amine (1d) was obtained as (400 MHz, CDCl
as a yellow powder. Yield: 0.82 g, 80%. Mp: 284–286 C. H-NMR
) d (ppm): 8.33 (d, J ¼ 9.2 Hz, 2H), 8.20 (d, J ¼ 8.0
a faint yellow power solid. Yield: 0.53 g, 43%. Mp: 131–132 C. Hz, 2H), 8.12–7.99 (m, 10H), 7.93 (d, J ¼ 9.2 Hz, 2H), 7.78 (d, J ¼
3
ꢀ
1
13
H-NMR (600 MHz, d
6
-DMSO) d (ppm): 8.71 (s, 1H), 8.39 (d, J ¼ 8.4 Hz, 2H), 6.87 (m, 4H). C-NMR (101 MHz, CDCl
3
) d (ppm):
6
¼
.0 Hz, 1H), 8.18–8.15 (m, 3H), 8.12 (d, J ¼ 9.6 Hz, 1H), 8.04 (d, J 158.92 (s), 156.53 (s), 147.35 (s), 142.42 (s), 131.08 (s), 128.96 (s),
9.0 Hz, 1H), 8.01–7.99 (m, 1H), 7.96 (d, J ¼ 9.0 Hz, 1H), 7.86 (d, 127.84 (s), 127.28 (s), 126.81 (s), 126.60 (s), 126.47 (s), 126.26 (s),
13
J ¼ 7.8 Hz, 1H), 7.21–7.19 (m, 2H), 7.16–7.13 (m, 2H). C-NMR 125.86 (d, J ¼ 6.7 Hz), 125.22–124.95 (m), 123.34 (s), 122.03 (d, J ¼
+
(ppm): (151 MHz, d
6
-DMSO) d 157.98 (s), 156.42 (s), 141.27 (s), 7.8 Hz), 115.98 (s), 115.75 (s). MALDI TOF-MS: m/z 511.284 [M] .
39.00 (s), 131.94 (s), 131.61 (s), 127.93 (s), 126.78 (s), 126.43 (d, J Elemental analysis: anal. calcd for C38 22FN: C, 89.21; H, 4.33; N,
5.1 Hz), 125.92 (s), 125.62 (s), 124.97 (d, J ¼ 6.8 Hz), 124.74 (s), 2.74. Found: C, 88.01; H, 4.15; N, 2.96%.
Synthesis of N-p-(nitro)-phenyl-N,N-dipyrenyl-1-amine (2e).
1
H
¼
1
24.34 (s), 122.67 (s), 121.16 (s), 119.79 (d, J ¼ 8.2 Hz), 116.52 (s),
1
16.36 (s), 116.21 (s). Elemental analysis: anal. calcd for Under the atmosphere of nitrogen, a mixture of 1-bromopyrene
C H FN: C, 85.42; H, 5.30; N, 4.33; O, 4.95. Found: C, 85.38; H, (1.41 g, 5 mmol), 4-nitroaniline (0.29 g, 2.6 mmol), Pd(dba) (96
2
2
14
2
+
ꢁ1
5
.35; N, 4.30%. GC/MSD: m/z 311 [M]
mg, 0.1 mmol), P(t-Bu) (0.1 g mL in toluene, 0.30 mL, 0.15
3
General procedure for synthesis of N-p-(R)-phenyl-N,N- mmol), sodium tert-butoxide (0.25 g, 2.6 mmol) and toluene (45
ꢀ
dipyrenyl-1-amine (2a–2d). Under the atmosphere of nitrogen, mL) were heated at 80 C for 4–5 h. Aer it cooled, water and
a mixture of 1-bromopyrene (0.56 g, 2 mmol), the secondary dichloromethane were added and the organic layer was sepa-
amines (1a–1d) (2.2 mmol), Pd(dba)
2
(18 mg, 0.02 mmol), P(t- rated. Then, the organic layer was dried over MgSO
4
and the
ꢁ
1
Bu)
3
(0.1 g mL in toluene, 0.06 mL, 0.03 mmol), sodium tert- solvent was removed under vacuum, resulting in yellow solid.
butoxide (0.21 g, 2.2 mmol) and toluene (20 mL) were heated at Finally, the crude products were puried by silica gel column
ꢀ
8
0 C for 4–5 h. Aer it cooled, water and dichloromethane were chromatography using hexane/dichloromethane mixture as
added and the organic layer was separated. Then, the organic eluent. The product (2e) was obtained as a yellow power solid.
ꢀ
1
layer was dried over MgSO and the solvent was removed under Yield: 0.83 g, 77%. Mp: 215–217 C. H-NMR (400 MHz, CDCl )
4
3
vacuum, resulting in yellow solid. Finally, the crude products d (ppm): 8.31–8.23 (m, 6H), 8.16–8.07 (m, 10H), 8.02 (d, J ¼ 9.2
1
3
were puried by silica gel column chromatography using Hz, 2H), 7.96 (d, J ¼ 8.0 Hz, 2H), 6.68 (s, 2H). C-NMR (101
hexane/dichloromethane mixture as eluent. MHz, d -DMSO) d (ppm): 131.20 (s), 130.79 (s), 130.45 (s), 129.56
N-Phenyl-N,N-dipyrenyl-1-amine (2a) was obtained as (s), 128.25 (s), 127.63 (s), 127.37 (s), 126.97 (d, J ¼ 9.4 Hz), 126.56
6
ꢀ
1
a yellow powder solid. Yield: 0.74 g, 75%. Mp > 300 C. H-NMR (s), 126.28 (d, J ¼ 11.1 Hz), 125.87 (s), 124.39 (s), 122.66 (s).
9046 | RSC Adv., 2016, 6, 9037–9048
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+
MALDI TOF-MS: m/z 538.287 [M] . Elemental analysis: anal.
References
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3
8
22 2 2
H, 4.43; N, 5.03%.
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4
4
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ꢁ
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Yield: 1.64 g, 50%. Mp > 300 C. H-NMR (400 MHz, CDCl )
3
d (ppm): 8.40 (dd, J ¼ 9.2 Hz, 3H), 8.23–8.17 (m, 3H), 8.09–7.91
(
1
m, 13H), 7.76 (d, J ¼ 2.4 Hz, 1H), 7.74 (d, J ¼ 2.4 Hz, 1H), 7.72 (s, 10 Z. Ning, Z. Chen, Q. Zhang, Y. Yan, S. Qian, Y. Cao and
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3
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3
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H
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