Synthesis, crystal packing, and ambipolar carrier transport property of twisted dibenzo[g,p]chrysenes

Article abstract of DOI:10.1002/asia.201402102

A versatile method for the synthesis of dibenzo[g,p]chrysene (DBC) derivatives based on regio- and stereoselective stannyllithiation to diarylacetylenes is described. This method affords a variety of DBCs possessing both electron-donating and electron-withdrawing functional groups. These twisted molecules take brickwork packing structures in single crystals. Thus, ambipolar carrier transport properties with mobility values of up to 10^-3 cm² V^-1 s^-1 in the amorphous state were achieved. Functional groups on DBC frameworks are considered to increase carrier mobility through the enhancement of intermolecular interactions in the brickwork packing structures. More than bricks and mortar: Dibenzo[g,p]chrysenes possessing a variety of substituents were synthesized. Single-crystal X-ray diffraction studies of these compounds revealed that they possess twisted molecular and brickwork packing structures. These structures are useful for their application to carrier transport materials.

Full text of DOI:10.1002/asia.201402102

FULL PAPER
DOI: 10.1002/asia.201402102
Synthesis, Crystal Packing, and Ambipolar Carrier Transport Property of
Twisted DibenzoACTHNUTRGNEUGN[g,p]chrysenes
Yasuyuki Ueda,[a] Hayato Tsuji,*[a, b] Hideyuki Tanaka,[a] and Eiichi Nakamura*[a]
Abstract: A versatile method for the
synthesis of dibenzo[g,p]chrysene
ing structures in single crystals. Thus,
ambipolar carrier transport properties
with mobility values of up to
10À3 cm2 VÀ1 sÀ1 in the amorphous state
were achieved. Functional groups on
DBC frameworks are considered to in-
crease carrier mobility through the en-
hancement of intermolecular interac-
tions in the brickwork packing struc-
tures.
AHCTUNGTRENNUNG
(DBC) derivatives based on regio- and
stereoselective stannyllithiation to dia-
rylacetylenes is described. This method
affords a variety of DBCs possessing
both electron-donating and electron-
withdrawing functional groups. These
twisted molecules take brickwork pack-
Keywords: electron transport
·
fused-ring systems · polycycles ·
solid-state structures
design
· synthesis
Introduction
lacetylenes that is followed by palladium-catalyzed coupling
and condensation reactions.[11] This method is potentially ap-
plicable to the synthesis of DBCs possessing both electron-
donating and electron-withdrawing substituents, thus ex-
panding the synthetic scope for DBCs derivatives.[12] In the
present work, we experimentally demonstrate the versatility
of this new approach, describe the crystal packing of DBCs,
and discuss their properties, including the ambipolar carrier
mobility. The significance of the functional groups on DBC
frameworks is also discussed from the viewpoint of property
tuning, involving the enhancement of carrier mobility.
Polycyclic aromatic hydrocarbons have attracted much at-
tention because of their characteristic optical properties,
chemical and thermal stability, and carrier transport ability
via intermolecular interactions of the p-electron system.[1]
While twisted fused aromatic compounds have long in-
trigued chemists because of the influence of the twist on the
p-conjugation,[2,3] more recent studies have focused on the
effect of the twist on molecular packing and the resulting
solid state properties, such as carrier transportation.[4–6]
Some types of fused aromatic molecules show innate non-
planar characteristics because of steric congestion caused by
peripheral hydrogen atoms.[7] Dibenzo
G
Results and Discussion
is representative of these types, as reported for nonsubstitut-
ed[8] and methoxy-substituted[9] derivatives. Studies of the
electronic properties of DBCs in the solid state have been
hampered, however, because of synthetic limitations. Previ-
ous syntheses of DBCs depended largely on an oxidative
cyclization reaction via a radical cation; they precluded the
synthesis of DBCs possessing electron-deficient substituents
and unsymmetrically substituted compounds.[9,10] We recent-
ly reported a new synthetic method that relies on a selective
regio- and stereoselective stannyllithiation reaction to diary-
The synthesis of unsymmetrically trifunctionalized DBC 1 il-
lustrates the effectiveness of the stannyllithiation-based syn-
thetic method (Scheme 1). First, addition of trimethylstan-
nyllithium to (4-methoxyphenyl)phenylacetylene afforded
a (2-stannylvinyl)lithium intermediate in 100% stereoselec-
tivity and 91:9 regioselectivity, as described in the top equa-
tion. This was confirmed by NMR spectroscopic analysis of
the protonated and arylated products.[12] This intermediate
was then converted into triarylstannyl alkenes using the Ne-
gishi cross-coupling reaction, as shown in the second equa-
tion. The Migita–Kosugi–Stille cross-coupling reaction with
an aryl iodide, shown in the third equation, afforded a tet-
raaryl alkene possessing two bromine atoms. Finally, an in-
tramolecular dehydrobromination reaction in the presence
of a palladium catalyst afforded an unsymmetrically func-
tionalized DBC derivative 1 possessing both an electron-do-
nating methoxy group and electron-withdrawing nitro and
trifluoromethyl groups.
[a] Dr. Y. Ueda, Dr. H. Tsuji, Dr. H. Tanaka, Prof. Dr. E. Nakamura
Department of Chemistry, School of Science
The University of Tokyo
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
E-mail: tsuji@chem.s.u-tokyo.ac.jp
nakamura@chem.s.u-tokyo.ac.jp
[b] Dr. H. Tsuji
JST-PRESTO
4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)
This synthetic method allowed us to obtain a variety of
DBC derivatives, as shown in Figure 1. Both electron-donat-
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/asia.201402102.
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Eiichi Nakamura, Hayato Tsuji et al.
Figure 1. Synthetic variations of DBC derivatives. [a] Overall yield in 5
steps. The other values indicate the overall yield in 3 steps from diaryl al-
kynes.
used oxidative methods.[10] Further conversion from a DBC
derivative was also possible. DibenzoACHTUNTRGNEUNG[g,p]chrysene-2,10-diyl-
bis(trifluoromethanesulfonate) (6) was synthesized by de-
protection of methyl groups of 2,10-dimethoxy-DBC (3) by
boron tribromide and a following reaction with triflic anhy-
dride (Scheme 2).
Scheme 1. Selective synthesis of multifunctionalized DBCs 1. Isomer
1
ratios were determined from the H NMR spectra of isomer mixtures.
ing groups, such as methyl and methoxy groups, and elec-
tron-withdrawing groups, such as cyano and nitro groups
and halogen atoms, could be installed on DBC cores. DBC
derivatives possessing strong electron-withdrawing groups
were particularly difficult to access by means of commonly
Scheme 2. Synthesis of dibenzoACTHUNGTRENN[UGN g,p]chrysene-2,10-diyl-bis(trifluorometha-
nesulfonate) (6).
Abstract in Japanese:
Single-crystal X-ray crystallography of some DBC deriva-
tives revealed their characteristic twisted molecular struc-
tures and packing structures (Figure 2). Their torsion angles
ranged from 28.68 ((MeO)2-DBC, 3) to 37.38 (Cl2-DBC, 5),
which implies that these angles are variable, depending on
the substituents on the DBC cores. Moreover, because of
the twisted molecular structures, all of these DBC deriva-
tives possess brickwork packing structures, whose interlayer
distances range from 3.78 to 3.91 ꢁ.[13]
Versatility of the stannyllithiation-based synthesis of DBC
derivatives led to diverse properties. The DBC derivatives
in dilute dichloromethane solution (ca. 10À5–10À6 molLÀ1)
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Eiichi Nakamura, Hayato Tsuji et al.
Table 1. Photophysical properties of DBC derivatives 2–10.
Cmpd.
labs, max
emax ꢂ10À4
[MÀ1 cmÀ1
Optical gap
[eV][a]
lem, max
FF
[nm]
G
]
[nm]
2
3
4
5
6
7
8
9
302
304
304
304
254
271
268
264
313
6.00
6.22
4.43
4.23
2.71
2.34
3.18
4.21
7.83
3.13
3.00
3.13
3.12
2.87
2.54
2.79
2.59
3.02
394
426
400
401
–
541
424
608
423
0.13
0.41
0.12
0.04
0.00
0.20
0.41
0.40
0.41
10
[a] Determined according to the following equation: Eg [eV]=1240/lonset
.
cyano groups (8) have high quantum yields up to 0.41.
These results indicate that functionalization significantly af-
fects the optical properties of DBC derivatives.
Substituents also change the electrochemical properties of
the DBC derivatives (Figure 3 and Table 2). Cyclic voltam-
metry (CV) measurements in dichloromethane of DBCs
Table 2. Electrochemical properties of DBC derivatives 2–10.
Cmpd.
Eox,1st [V]
Ered,1st [V]
EHOMO [eV]
ELUMO [eV]
2
3
4
5
6
7
8
9
0.90
0.70
0.76
0.98
1.18
–
–
0.99
0.89
–
–
–
–
À5.70[a]
À5.50[a]
À5.56[a]
À5.78[a]
À5.98[a]
À5.79[c]
À5.58[c]
À5.79[a]
À5.66[a]
À2.57[c]
À2.50[c]
À2.43[c]
À2.66[c]
À3.22[b]
À3.25[b]
À2.80[b]
À3.27[b]
À2.64[c]
À1.58
À1.55
À2.00
À1.53
–
10
[a] Determined from oxidation potentials observed by CV measurements
in dichloromethane (ca. 10À3 molLÀ1) in the presence of tetrabutylammo-
nium perchlorate as an electrolyte, according to the following equation:
EHOMO [eV]=À(4.80+Eox,1st [V]). [b] Determined from reduction poten-
tials observed by CV measurements, according to the following equation:
ELUMO [eV]=À(4.80+Ered,1st [V]). [c] Determined from the corresponding
EHOMO or ELUMO values, determined by CV, and the optical band gap.
Figure 2. Molecular and packing structures of DBCs. (a) Torsion angles
determined as the dihedral angles defined by the four carbons atoms
(aC1-C2-C3-C4). (b) Nonsubstituted DBC 2, (c) (MeO)2-DBC 3, (d) Me2-
DBC 4, (e) Cl2-DBC 5, and (f) (TfO)2-DBC 6.
possessing electron-donating groups showed no reduction
but only reversible oxidation peaks, ranging from 0.70 V (3
with methoxy groups) to 0.99 V (5 with chlorine atoms). On
the other hand, CV measurements of DBCs possessing elec-
tron-withdrawing groups showed only reversible reduction
waves, ranging from À2.00 V (8 with cyano groups) to
À1.55 V (7 with nitro groups). However, (TfO)2-DBC 6 and
Me-NO2-DBC 9 are exceptions, as they both showed rever-
sible oxidation and reduction waves. HOMO and LUMO
levels of DBC derivatives were estimated by the oxidation
and reduction potentials, and absorption onset wavelengths
(Table 2). Their HOMO levels ranged from À5.50 eV (3
with electron-donating methoxy groups) to À5.98 eV (6 with
electron-withdrawing trifluoromethanesulfonyl groups).
Their LUMO levels ranged from À2.43 eV (4 with electron-
donating methyl groups) to À3.27 eV (9 with electron-with-
drawing nitro groups).
showed intense UV absorption and modest emission
(Figure 3 and Table 1). Introduction of two nitro groups
caused red shifts in the absorption because of expanded p-
conjugated systems. The nitro groups also caused significant
red shifts in the emission. The emission maximum wave-
lengths of NO2-DBC 7 and Me-NO2-DBC 9 are 541 nm and
608 nm, respectively, while those of the other DBC deriva-
tives appear at shorter wavelengths (between 395 nm and
424 nm). The nitro groups significantly perturb the excited
states.[14] The quantum yields of DBC emission vary. While
DBCs possessing chlorine atoms (5) or trifluoromethanesul-
fonyl groups (6) are almost nonemissive, those possessing
either strong electron-donating groups such as methoxy
groups (3) or strong electron-withdrawing groups such as
3
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Eiichi Nakamura, Hayato Tsuji et al.
orbitals and the brickwork
packing. Density functional
theory (DFT) calculations at
the
B3LYP/6-31G(d)
level
showed that the frontier molec-
ular orbital coefficients of func-
tionalized DBCs tend to be
larger on the functionalized
parts of the molecules (Fig-
ure 5b and c), while they are
almost equal over all carbon
atoms of the nonsubstituted
DBC 2 (Figure 5a). In addition,
a single-crystal X-ray diffrac-
tion study of (MeO)2-DBC 3
revealed that the brickwork
packing structure of this com-
pound enhances the intermolec-
ular interactions of the func-
tionalized parts in the crystal
(Figure 5d). Therefore, stronger
intermolecular interactions are
achieved, which subsequently
increase the carrier mobility of
the functionalized derivatives.
Figure 3. Properties of the DBCs. Left column: absorption (abs.) and emission (em.) spectra of DBC deriva-
tives 3, 7, and 9 in dichloromethane at room temperature. Right column: cyclic voltammograms in dichlorome-
thane.
Conclusions
We have shown that a mild and
selective synthetic method that
Carrier transport measurements of DBC derivatives, using
the time-of-flight (TOF) technique, revealed that these com-
pounds display ambipolar carrier transport properties
(Table 3 and Figure 4). These properties are probably due to
the formation of efficient carrier transport paths due to the
brickwork packing structures. In addition, substituted DBCs
relies on stannyllithiation affords a variety of DBC deriva-
tives that were hitherto unavailable by conventional synthet-
ic methods. Crystal structures of the DBCs showed that all
of them possess twisted molecular structures, and such twist-
ed molecular structures result in the formation of brickwork
packing structures. It is believed that these structures cause
ambipolar carrier mobilities, which reached the order of
10À3 cm2 VÀ1 sÀ1. Functionalization of DBCs is useful for the
tuning of not only their optical and electrochemical proper-
ties but also carrier mobility values, as a result of the forma-
tion of efficient carrier transport paths caused by strong in-
termolecular interactions among localized molecular orbitals
in the brickwork packing structure. We expect that function-
alized DBCs will serve as useful scaffolds for the design of
organic electronic and photonic materials.[15]
Table 3. Carrier mobility values of DBC derivatives at an electric field of
2.5ꢂ105 VcmÀ1
.
Cmpd.
Hole mobility
Electron mobility
[cm2 VÀ1 sÀ1
]
[cm2 VÀ1 sÀ1
]
2
3
10
7.9ꢂ10À5
4.1ꢂ10À4
9.5ꢂ10À5
2.7ꢂ10À5
1.9ꢂ10À4
1.4ꢂ10À3
show higher hole and electron mobilities than the nonsubsti-
tuted DBC (2). Nonsubstituted DBC 2 has hole and elec-
tron mobilities of 7.9ꢂ10À5 cm2 VÀ1 sÀ1 and 2.7ꢂ
10À5 cm2 VÀ1 sÀ1, respectively, at an electric field of 2.5ꢂ
105 VcmÀ1, while (MeO)2-DBC 3 has hole and electron mo-
bilities of 4.1ꢂ10À4 cm2 VÀ1 sÀ1 and 1.9ꢂ10À4 cm2 VÀ1 sÀ1 and
CN-MeO-DBC (10) has mobilities of 9.5ꢂ10À5 cm2 VÀ1 sÀ1
and 1.4ꢂ10À3 cm2 VÀ1 sÀ1, respectively, at the same electric
field.
Experimental Section
Synthesis of (E)-[2-(2-Bromophenyl)-1,2-diphenyl]vinyltrimethylstannane
Hexamethyldistannane (0.5 molLÀ1 in THF, 10 mL, 5.0 mmol) was vigo-
rously stirred with lithium granules (140 mg, 20 mmol) at 08C for 12 h.[16]
A portion of the resulting dark green mixture (5.5 mL) was then trans-
ferred via a gas-tight syringe to another reaction vessel, and the volatiles
were removed in vacuo. Subsequently, n-hexane and diphenylacetylene
(900 mg, 5.0 mmol) were added. After vigorous stirring at 08C for 3 h,
zinc chloride (1.0 molLÀ1 in THF, 5.5 mL, 5.5 mmol) was added. The re-
The enhanced carrier mobilities of the functionalized
DBCs can be ascribed to a synergism of localized molecular
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Eiichi Nakamura, Hayato Tsuji et al.
action mixture was then allowed to
warm to room temperature. After stir-
ring for 30 min, tris(dibenzylideneace-
tone)dipalladium-chloroform
adduct
(280 mg, 0.27 mmol), 2-dicyclohexyl-
phosphino-2’,6’-dimethoxybiphenyl[17]
(SPhos, 410 mg, 1.0 mmol), and 1-
bromo-2-iodobenzene
(1.4 g,
4.9 mmol) were added. After stirring
at room temperature for 1 h, water
(10 mL) was added, and the resulting
mixture was extracted five times with
diethyl ether (10 mL). The combined
organic layers were then passed
through a pad of silica gel. After con-
centration in vacuo, purification by
flash column chromatography on silica
gel (eluent: n-hexane) afforded the
title compound (1.9 g, 76% yield) as
a
colorless solid. M.p. 155–1568C;
1H NMR (500 MHz, CDCl3): d=À0.13
(s, 2JSn-H =54/52 Hz, 9H, Sn
ACHTUNGTRENNUNG(CH3)3),
6.88 (dt, J=1.7, 7.5 Hz, 1H, ArH),
6.94–6.98 (m, 3H; ArH), 7.06–7.11 (m,
3H; ArH), 7.18 (dd, J=1.7, 8.1 Hz,
1H; ArH), 7.28 (d, J=7.5 Hz, 1H;
ArH), 7.30–7.33 (m, 3H; ArH),
7.44 ppm (d, J=6.9 Hz, 2H; ArH);
13C NMR (125 MHz, CDCl3): d=À7.1,
Figure 4. (a) Carrier drift mobilities of MeO-CN-DBC 10 plotted against the square root of the electric field
by the time-of-flight (TOF) method at room temperature. (b, c) Transient photocurrent signals of MeO-CN-
DBC 10 at an applied field of 2.5ꢂ104 VcmÀ1 (b: hole, c: electron).
122.9, 124.8, 126.4, 127.1, 127.4, 127.8, 128.0, 129.4, 131.59, 131.64, 132.4,
143.4, 143.5, 144.8, 150.1, 151.4 ppm; GC-MS (EI) 485 ([M]+ for
C23H2381Br120Sn), 483 ([M]+ for C23H2381Br118Sn and C23H2379Br120Sn), 481
([M]+ for C23H2379Br118Sn); elemental analysis calcd (%) for C23H23BrSn:
C 55.47, H 4.65; found: C 55.35, H 4.54.
Synthesis of (E)-1,2-Bis(2-bromophenyl)-1,2-diphenylethene
N,N-Dimethylformamide (1.2 mL) was added to a mixture of (E)-[2-(2-
bromophenyl)-1,2-diphenyl]-vinyltrimethylstannane (290 mg, 0.59 mmol),
1-bromo-2-iodobenzene (180 mg, 0.63 mmol), tetrakis(triphenylphosphi-
ne)palladium(0) (33 mg, 30 mmol), copper(I) iodide (13 mg, 69 mmol),
and cesium fluoride (200 mg, 1.3 mmol). After stirring for 3 h at 608C,
water (5 mL) was added, and the resulting mixture was extracted five
times with dichloromethane (5 mL). The combined organic layers were
then passed through a pad of silica gel. After concentration in vacuo, pu-
rification by recrystallization over methanol afforded the title compound
(250 mg, 86% yield) as a mixture of two conformational isomers as a col-
orless solid. M.p. 167–1698C; 1H NMR (500 MHz, CDCl3): d=7.05–7.08
(m, 13H; ArH), 7.12–7.14 (m, 1H, ArH), 7.20 (t, J=14.9 Hz, 1H; ArH),
7.38 (dd, J=1.7, 7.5 Hz, 1H; ArH), 7.46 (d, J=8.0 Hz, 1H; ArH),
7.54 ppm (d, J=7.5 Hz, 1H; ArH); 13C NMR (125 MHz, CDCl3): d=
124.4, 125.6, 126.7, 126.8, 126.9, 127.0, 127.3, 127.4, 128.5, 129.9, 130.1,
132.8, 133.0, 133.3, 140.6, 141.1, 141.6, 143.3, 143.4 ppm; GC-MS (EI) 492
(M+ for C26H1881Br2), 490 (M+ for C26H1879Br81Br), 488 (M+ for
C26H1879Br2); elemental analysis calcd (%) for C26H18Br2: C 63.70, H 3.70;
found: C 63.55, H 3.64.
Synthesis of DibenzoACTHNUGRTNEUNG[g,p]chrysene (2)
N,N-Dimethylformamide (2.0 mL) was added to a mixture of (E)-1,2-
bis(2-bromophenyl)-1,2-diphenylethene (49 mg, 0.10 mmol), palladiu-
m(II) acetate (2.0 mg, 10 mmol), tricyclohexylphosphonium tetrafluorobo-
rate (6.0 mg, 20 mmol), potassium carbonate (27 mg, 0.20 mmol), and
silver carbonate (14 mg, 50 mmol). After stirring for 21 h at 1308C, water
(5 mL) was added, and the resulting mixture was extracted three times
with dichloromethane (5 mL). The combined organic layers were passed
through a pad of silica gel. After concentration in vacuo, purification by
flash column chromatography on silica gel (eluent: n-hexane) afforded
the title compound (2, 30 mg, 89%) as a colorless solid. Analytical data
were in good accordance with data reported in the literature.[10a]
Figure 5. HOMO/LUMO of DBCs estimated by DFT calculation at the
B3LYP/6-31G(d) level of theory: (a) 2, (b) 3, and (c) 10. (d) Molecular
overlap in crystals of (MeO)2-DBC 3.
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Eiichi Nakamura, Hayato Tsuji et al.
General
Chem. Asian J. 2012, 7, 561–564; g) J. Xiao, Y. Divayana, Q. Zhang,
H. M. Doung, H. Zhang, F. Boey, X. W. Sun, F. Wudl, J. Mater.
Chem. 2010, 20, 8167–8170.
UV/Vis absorption spectra were recorded using a UV/Vis spectrometer
(V-570; Jasco). Spectroscopy-grade dichloromethane was used as solvent.
Sample solutions (ca. 10À5 molLÀ1) in a 1 cm square quartz cell were
used for the measurements. Fluorescence emission spectra were recorded
on a fluorescence spectrometer (FP-6500; Jasco). Absolute quantum
yields (FF) were recorded with a photonic multichannel analyzer (PMA-
12; Hamamatsu Photonics). Degassed spectroscopy-grade dichlorome-
thane was used as solvent. Sample solutions (ca. 10À6 molLÀ1) in a 1 cm
square quartz cell were used for the measurements. All measurements
were performed at ambient temperature.
[3] For reviews of various types of nonplanar p-conjugated systems,
see: a) Y.-T. Wu, J. S. Siegel, Chem. Rev. 2006, 106, 4843–4867;
b) V. M. Tsefrikas, L. T. Scott, Chem. Rev. 2006, 106, 4868–4884;
c) T. Yao, H. Yu, R. J. Vermeij, G. J. Bodwell, Pure Appl. Chem.
2008, 80, 533–546; d) Z. S. Yoon, A. Osuka, D. Kim, Nat. Chem.
2009, 1, 113–122; e) A. Osuka, S. Saito, Chem. Commun. 2011, 47,
4330–4339; f) T. Amaya, T. Hirao, Chem. Commun. 2011, 47,
10524–10535; g) S. Higashibayashi, R. Tsuruoka, Y. Soujanya, U.
Purushotham, G. N. Sastry, S. Seki, T. Ishikawa, S. Toyota, H. Sakur-
ai, Bull. Chem. Soc. Jpn. 2012, 85, 450–467; h) E. S. Hirst, R. Jasti,
J. Org. Chem. 2012, 77, 10473–10478; i) H. Omachi, Y. Segawa, K.
Itami, Acc. Chem. Res. 2012, 45, 1378–1389; j) S. Yamago, E. Kaya-
hara, T. Iwamoto, Chem. Rec. 2014, 14, 84–100.
[4] For example, see: M. Gsꢃnger, J. H. Oh, M. Kçnemann, H. W.
Hçffken, A.-M. Krause, Z. Bao, F. Wꢄrthner, Angew. Chem. Int. Ed.
2010, 49, 740–743; Angew. Chem. 2010, 122, 752–755.
[5] For reports of carrier mobility of other non-planar p-conjugated
compounds, see: a) T. Amaya, S. Seki, T. Moriuchi, K. Nakamoto, T.
Nakata, H. Sakane, A. Saeki, S. Tagawa, T. Hirao, J. Am. Chem.
Soc. 2009, 131, 408–409; b) K. Shi, T. Lei, X.-Y. Wang, J.-Y. Wang,
J. Pei, Chem. Sci. 2014, 5, 1041–1045; c) ref. 3g.
Cyclic voltammetry (CV) was performed using a voltammetric analyzer
(HZ-5000; Hokuto Denko Corp.). A glassy carbon electrode was used as
the working electrode, platinum coil as the counter electrode, and Ag+
/Ag as the reference electrode. Cyclic voltammograms were measured at
a scan rate of 100 mVsÀ1 (three cycles per measurement). Oxidation po-
tentials were plotted using Fc/Fc+ as an internal reference (0 V). The
compounds were dissolved in degassed dichloromethane at a concentra-
tion of ca. 5ꢂ10À3 molLÀ1, and tetrabutylammonium perchlorate at a con-
centration of 0.1 molLÀ1 was added as an electrolyte. The dichlorome-
thane used was purified by a solvent purification system (Glass Contour)
equipped with columns of activated alumina and copper catalyst,[18] and
it was degassed prior to use.
[6] For example, see: X. Qiao, M. A. Padula, D. M. Ho, N. J. Vogelaar,
C. E. Schutt, R. A. Pascal, Jr., J. Am. Chem. Soc. 1996, 118, 741–
745.
[7] a) D. PeÇa, D. Pꢅrez, E. Guitiꢆn, L. Castedo, Org. Lett. 1999, 1,
1555–1557; b) D. PeÇa, A. Cobas, D. Pꢅrez, E. Guitiꢆn, L. Castedo,
Org. Lett. 2000, 2, 1629–1632.
[8] F. H. Herbstein, Acta Crystallogr. Sect. B 1979, 35, 1661–1670.
[9] a) S. Yamaguchi, T. M. Swager, J. Am. Chem. Soc. 2001, 123, 12087–
12088; b) T. S. Navale, L. Zhai, S. V. Lindeman, R. Rathore, Chem.
Commun. 2009, 2857–2859.
[10] For examples of the conventional synthetic methods for DBC deriv-
atives, see a) M. Shimizu, I. Nagao, Y. Tomioka, T. Hiyama, Angew.
Chem. Int. Ed. 2008, 47, 8096–8099; Angew. Chem. 2008, 120, 8216–
8219; b) R. Chaudhuri, M.-Y. Hsu, C.-W. Li, C.-I. Wang, C.-J. Chen,
C. K. Lai, L.-Y. Chen, S.-H. Liu, C.-C. Wu, R.-S. Liu, Org. Lett.
2008, 10, 3053–3056; c) K. Mochida, K. Kawasumi, Y. Segawa, K.
Itami, J. Am. Chem. Soc. 2011, 133, 10716–10719.
[11] K. Kamikawa, I. Takemoto, S. Takemoto, H. Matsuzaka, J. Org.
Chem. 2007, 72, 7406–7408.
[12] H. Tsuji, Y. Ueda, L. Ilies, E. Nakamura, J. Am. Chem. Soc. 2010,
132, 11854–11855.
[13] Octamethoxy-substituted DBC, reported in ref. 9b, does not have
brickwork packing structures because of the incorporation of crystal
solvent.
[14] R. Arce, E. F. Pino, C. Valle, I. Negrꢇn-Encarnacꢈon, M. Morel, J.
Phys. Chem. A 2011, 115, 152–160.
Time-of-flight (TOF) measurements were performed using a TOF-401 in-
strument (Sumitomo Heavy Industries, Advanced Machinery; Tokyo,
Japan). The typical fabrication procedure used to prepare samples for the
measurements was as follows. Amorphous films of DBC derivatives were
prepared on glass substrates coated with thin films of indium tin oxide
(ITO, 145 nm). The vacuum deposition was performed on a vacuum
vapor deposition apparatus (VPC-260; Ulvac Kiko). The films of DBC
derivatives were deposited by vacuum sublimation at 9ꢂ10À4 Pa with
a deposition rate of <10 nmsÀ1. The ITO-coated glass substrates were
spaced at a distance of 100 mm from the sample. They were kept at
258C. The thickness of the films of DBCs obtained was 1.0–1.7 mm. After
aluminum electrode deposition (80 nm), the devices were encapsulated
under a nitrogen atmosphere.
Acknowledgements
This work was supported by a “Specially Promoted Research” grant
(KAKENHI 22000008 to E.N.), by JST-PRESTO “New Materials Sci-
ence and Element Strategy” (for H.T.), and by the Strategic Promotion
of Innovative Research and Development from the Japan Science and
Technology Agency (JST). Y.U. thanks the Japan Society for the Promo-
tion of Science for Young Scientists for a Research Fellowship (No. 25-
10265).
[15] A nitrogen- and boron-doped DBC also has a higher hole transport
mobility value than that of a nonsubstituted DBC because of their
localized molecular orbitals. T. Hatakeyama, S. Hashimoto, S. Seki,
M. Nakamura, J. Am. Chem. Soc. 2011, 133, 18614–18617.
[16] K. Kobayashi, M. Kawanisi, T. Hitomi, S. Kozima, J. Organomet.
Chem. 1982, 233, 299–311.
[17] T. E. Barder, S. D. Walker, J. R. Martinelli, S. L. Buchwald, J. Am.
Chem. Soc. 2005, 127, 4685–4696.
[18] A. B. Pangborn, M. A. Giardello, R. H. Grubbs, F. J. Timmers, Orga-
nometallics 1996, 15, 1518–1520.
[1] J. C. Fetzer, Polycyclic Aromat. Compd. 2007, 27, 143–162.
[2] For reviews: a) R. A. Pascal, Jr., Chem. Rev. 2006, 106, 4809–4819;
b) Y. Shen, C.-F. Chen, Chem. Rev. 2012, 112, 1463–1535. For recent
examples: c) J. Xiao, H. M. Duong, Y. Liu, W. Shi, L. Ji, G. Li, S. Li,
X.-W. Liu, J. Ma, F. Wudl, Q. Zhang, Angew. Chem. Int. Ed. 2012,
51, 6094–6098; Angew. Chem. 2012, 124, 6198–6202; d) G. Li, H. M.
Duong, Z. Zhang, J. Xiao, L. Liu, Y. Zhao, H. Zhang, F. Huo, S. Li,
J. Ma, F. Wudl, Q. Zhang, Chem. Commun. 2012, 48, 5974–5986;
e) J. Xiao, C. D. Malliakas, Y. Liu, F. Zhou, G. Li, H. Su, M. G. Ka-
natzidis, F. Wudl, Q. Zhang, Chem. Asian J. 2012, 7, 672–675; f) J.
Xiao, S. Liu, Y. Liu, L. Ji, X. Liu, H. Zhang, X. Sun, Q. Zhang,
Received: February 22, 2014
Published online: && &&, 0000
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Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
ÝÝ These are not the final page numbers!

FULL PAPER
More than bricks and mortar:
Polycycles
DibenzoACHTUNGTRENNUNG[g,p]chrysenes possessing
a variety of substituents were synthe-
sized. Single-crystal X-ray diffraction
studies of these compounds revealed
that they possess twisted molecular
and brickwork packing structures.
These structures are useful for their
application to carrier transport materi-
als.
Yasuyuki Ueda, Hayato Tsuji,*
Hideyuki Tanaka,
Eiichi Nakamura*
&&&& — &&&&
Synthesis, Crystal Packing, and Ambi-
polar Carrier Transport Property of
Twisted DibenzoACTHNUTRGNEUGN[g,p]chrysenes
7
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&
Chem. Asian J. 2014, 00, 0 – 0
ꢀ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
These are not the final page numbers! ÞÞ