Synthesis, characterization, and bipolar transporting behavior of a new twisted polycyclic aromatic hydrocarbon: 1′,4′-diphenyl-naphtho- (2′.3′:1.2) -pyrene-6′-nitro-7′-methyl carboxylate

Article abstract of DOI:10.1002/chem.201000026

An asymmetric twistacene, l′,4′-diphenyl-naphtho-(2′. 3′:1.2)-pyrene-6′nitro-7′-methyl carboxylate (tetracene 2), was synthesized by using benzyne-trapping chemistry. Its structure, determined by X-ray crystallography, confirmed that this material has a twisted topology with torsion angles as high as 23.8(3)°. Organic light-emitting devices using tetracene 2 as either charge-transporting materials or emitters have been fabricated. The results indicate that this material has bipolar transporting behavior in these devices.

Full text of DOI:10.1002/chem.201000026

DOI: 10.1002/chem.201000026
Synthesis, Characterization, and Bipolar Transporting Behavior of a New
Twisted Polycyclic Aromatic Hydrocarbon: 1’,4’-Diphenyl-naphtho-(2’.3’:1.2)-
pyrene-6’-nitro-7’-methyl Carboxylate
Qichun Zhang,*[a] Yoga Divayana,[b] Jinchong Xiao,[a] Zhijuan Wang,[a]
Edward R. T. Tiekink,[a, e] Hieu M. Doung,[c] Hua Zhang,[a] Freddy Boey,[a]
Xiao Wei Sun,*[b] and Fred Wudl*[c, d]
Abstract: An asymmetric twistacene, 1’,4’-diphenyl-naphtho-(2’.3’:1.2)-pyrene-6’-
nitro-7’-methyl carboxylate (tetracene 2), was synthesized by using benzyne-trap-
Keywords: arenes
· light-emitting
ping chemistry. Its structure, determined by X-ray crystallography, confirmed that
this material has a twisted topology with torsion angles as high as 23.8(3)8. Organic
light-emitting devices using tetracene 2 as either charge-transporting materials or
emitters have been fabricated. The results indicate that this material has bipolar
transporting behavior in these devices.
device · polycycles · polycyclic aro-
matic hydrocarbons · semiconduc-
tors · synthesis design
Introduction
Polycyclic aromatic hydrocarbons (PAHs),[1–3] also known as
“pieces of graphene”, have generated strong interest both in
fundamental science underlying synthetic challenge, struc-
ture–property correlations, and stacking features in solid
states as well as in potential technological applications[4–6]
such as light-emitting diodes, field-effect transistors, and
photovoltaic devices.[7–9] In addition, these materials are
amenable to the fine tuning of their electrical and optical
properties by proper molecular design. One member of the
PAH family, pyrene (1), is of particular interest because it
[a] Prof. Q. Zhang, Dr. J. Xiao, Dr. Z. Wang, Prof. E. R. T. Tiekink,
Prof. H. Zhang, Prof. F. Boey
School of Materials Science Engineering
Nanyang Technological University
50 Nanyang Avenue, Singapore 639798 (Singapore)
Fax : (+65)67909081
E-mail: qczhang@ntu.edu.sg
[b] Dr. Y. Divayana, Prof. X. W. Sun
School of Electronical and Electronic Engineering
Nanyang Technological University
50 Nanyang Avenue, Singapore 639798 (Singapore)
Fax : (+65)67933318
E-mail: exwsun@ntu.edu.sg
[c] Dr. H. M. Doung, Prof. F. Wudl
Department of Chemistry and Biochemistry
University of California, Los Angeles, CA 90095 (USA)
[d] Prof. F. Wudl
Mitsubishi Chemical Centre for Advanced Materials
Department of Chemistry and Biochemistry and
Centre for Polymers and Organic Solids
University of California, Santa Barbara, CA 93106 (USA)
Fax : (+1)805-8934120
E-mail: wudl@chem.ucsb.edu
has the fundamental framework found in many PAHs,
carbon nanotubes, graphenes, and polycyclic heteroaromat-
ics. Accordingly, 1 has been widely employed as a molecular
scaffold to construct larger PAHs and heteroaromatics.
Recent reports have already demonstrated that pyrene-
[e] Prof. E. R. T. Tiekink
Current Address: Department of Chemistry
University of Malaya, 50603 Kuala Lumpur (Malaysia)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201000026.
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FULL PAPER
based materials possess excellent photoluminescence effi-
ciency, high carrier mobility, and enhanced hole-injecting
ability in organic light-emitting devices (OLEDs).[10–12]
A key limitation for PAHs application in OLEDs is their
concentration-quenching effect due to strong p-stacking in-
teractions.[13] One possible solution is to twist the PAHs, cre-
ating a more sterically hindered p system and, in effect, de-
crease p···p attractions. These topologically interesting
PAHs systems have been studied in great detail by Pascal.[14]
The basic strategy used to twist PAHs is to introduce bulky
substituents on their conjugated framework. Interestingly,
twisting PAHs has little effect on their characteristic spec-
troscopic and electronic properties when compared to their
unsubstituted planar parent structures. Therefore, these
twisted p systems provide an attractive molecular toolset for
application in OLEDs. In fact, an efficient white-light-emit-
ting diode based on a novel “twistacene” has been demon-
strated by Wudl and Yang.[15] Herein, we reported the syn-
thesis of a novel twistacene homologue and its bipolar elec-
tronic properties.
Crystal structure: The molecular structure of tetracene 2
with atomic labeling is illustrated in Figure 1 (top) and crys-
tal data are given in Table 1.[16a] Immediately evident from
the side-on view of the crystal packing of tetracene 2
Results and Discussion
Synthesis of materials: 1’,4’-Diphenyl-naphtho-(2’.3’:1.2)-
pyrene-6’-nitro-7’-methyl carboxylate (tetracene 2) was pre-
pared through benzyne-trapping chemistry of bisbenzyne
precursor 4 by using dienenone 3 (Scheme 1). The single-
Figure 1. Top: Molecular structure of tetracene 2 showing the crystallo-
À
À
graphic numbering scheme. Bottom: View along the Cphenyl C9···C12
C
phenyl axis highlighting the buckled nature of the carbon atom framework
À
À
and the twists in the terminal phenyl, C(=O)OMe, and NO2 residues.
Table 1. Crystal data and structure refinement for tetracene 2.
formula
Mr
C38H23NO4
557.60
Scheme 1. The synthetic route to tetracene 2.
T [K]
l [ꢁ]
crystal system
space group
a [ꢁ]
250
0.71073
triclinic
crystal X-ray structural analysis of tetracene 2 shows the an-
ticipated twisted topology in the dibenzotetracene PAH
scaffold. Taking advantage of this twist feature, we fabricat-
ed several OLEDs using tetracene 2 to study its electronic
transport properties.
¯
P1
9.0847(2)
b [ꢁ]
c [ꢁ]
a [8]
b [8]
11.5552(2)
13.9742(3)
78.850(1)
73.090(1)
Tetracene 2 was prepared through a [4+2] cycloaddition
involving in-situ aryne (benzyne formation) as a dienophile
g [8]
84.950(1)
1376.24(5)
2
1.346
0.087
V [ꢁ3]
Z
and pyrano-diphenylcyclopentadienone (3) as
a diene
1calcd [gcmÀ3
]
(Scheme 1). The intermediate benzyne precursor 4 was syn-
thesized from a commercially available aminoterephthalic
dimethyl ester in four steps. To avoid the nucleophilic dis-
placement of the nitro group by hydroxyl group, the ben-
zyne precursor 4 was introduced slowly as a 1,2-dichloro-
m [mmÀ1
F(000)
]
580
crystal size [mm]
2q range [8]
index ranges
0.30ꢂ0.23ꢂ0.22
3.6–51.8
À10ꢀhꢀ10
À13ꢀkꢀ13
À15ꢀlꢀ16
98.8%
ethane (DCE) suspension to an awaiting cyclopenta
ACHTUNGTRNEdNUNG iene-
ACHTUNGTRENNUNGone 3 with isoamyl nitrite in refluxing DCE. These condi-
completeness
max/min transmission
final R indices [I>2s(I)]
R indices (all data)
0.990/0.9550
R1=0.047, wR2=0.120
R1=0.069, wR2=0.137
tions afforded the target tetracene 2 in 45% without any
evidence of phenol formation.
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Q. Zhang, X. W. Sun, F. Wudl et al.
(Figure 1, bottom) is the presence of significant twist to the
dibenzotetracene p system in the molecule. There is also sig-
nificant puckering in each of the three endocyclic six-mem-
bered rings. Thus, the “hinge” atoms C6, C11, and C10 have
the greatest deviations of 0.053(2) (C3–C8 ring), 0.107(2)
(C6, C7, C9–C12) and 0.132(2) ꢁ (C10, C11, C25, C30–C32)
from their respective least-squares planes. Similar distor-
tions, although not as great, are evident in the 24-atom tricy-
clic systems, that is, the C25 (C25–C30 ring), C31 (C29-C31-
C36-C38) and C31 (C31–C36) atoms lie 0.026(2), 0.034(2)
and À0.041(2) ꢁ out of their respective least-squares plane.
A quantitative measure of the twisting in the molecule is
found in the magnitudes of the torsion angles involving the
À
À
À
C6 C7, C10 C11, and C30 C31 “hinges”, which vary from
a low of 6.7(3)8 for the C25-C30-C31-C32 torsion angle to a
high of 23.8(3)8 for C32-C10-C11-C25, indicating the great-
À
Figure 2. Top: Supramolecular chain formation through C H···O interac-
tions (shown as dashed lines). Bottom: Loose association between cen-
À
est twist occurs around the C10 C11 bond. The molecule
adopts a distinctively curved motif, which is aptly quantified
in terms of the dihedral angle formed between the terminal
C3–C8 and C29–C31/C36–C38 six-membered rings of
35.23(11)8.
À
trosymmetric molecules mediated by C H···p interactions (dashed lines).
The ester and the terminal phenyl rings in tetracene 2 is
twisted out of the plane of the central fused ring system as
manifested in the C6-C12-C13-C14 and C7-C9-C19-C24 tor-
sion angles of À66.9(3) and À71.3(2)8, respectively. As seen
from Figure 1 (bottom), the phenyl rings are orientated in
opposite directions. Each of the ester and nitro groups are
twisted out of the plane of the aromatic ring to which they
are connected as seen in the O1-C2-C3-C4 and O3-N1-C4-
C5 torsion angles of 47.8(3) and 30.2(3)8, respectively.
The most prominent intermolecular interactions stabiliz-
À
À
ing the crystal packing are of the type C H···O and C
H···p. As anticipated, the closet interactions in the solid
state are greater than 4.0 ꢁ due to the twisting of the mac-
Figure 3. UV/Vis and fluorescence spectra of tetracene 2 in DCM.
À
romolecular framework. The C H···O contact occurs be-
tween the phenyl-C18-H and the carbonyl-O1[16b] to form
were fabricated: 1) ITO/NPB (50 nm)/2
ACHTUNGTREN(NGNU 50 nm)/Mg:Ag, 2)
supramolecular chains along the a direction (Figure 2, top).
ITO/2(50 nm)/Alq3 (50 nm)/Mg:Ag, and 3) ITO/NPB
ACHTUNGTRENNUNG
À
The C H···p contacts occur between centrosymmetrically
(50 nm)/Alq3 (50 nm/Mg:Ag (standard device), in which
ITO is indium-tin-oxide; NPB is N,N’-bis(naphthalen-1-yl)-
related molecules through the phenyl-C14-H and the ring
centroid of the C25–C30 ring to form dimeric aggregates
(Figure 2, bottom) with the consequence that the supra-
N,N’-bis
(phenyl)benzidine,
a
common hole-transporting
layer, and Alq3 is tris(8-hydroxy-quinolinato) aluminium, a
common electron-transporting layer. In device 1, tetracene 2
acts as the electron-transporting layer, while it becomes
hole-transporting carrier in device 2. Figure 4 (top) shows
the current density for the corresponding devices. It can be
seen that there is no significant difference between devices 1
and 2, which shows that tetracene 2 transports both electron
and hole equally well. However, compared to the conven-
tional carrier transporting materials (device 3), tetracene 2
shows a relatively low carrier-transport capability. Inset of
Figure 4 (top) shows the emission spectrum of the corre-
sponding devices. Emission from device 1 comes from tetra-
cene 2, while the emission from device 2 is very similar to
found for standard device 3, which comes from Alq3. In
terms of external quantum efficiency (EQE), both devices
that utilize tetracene 2 as the carrier-transporting layer show
poor performance. The standard device reaches EQE of
À
molecular chains mediated by the C H···O contacts are
linked into double chains.[16c]
The UV/Vis absorption and fluorescence spectrum of tet-
racene 2 were recorded at room temperature in methylene
chloride (DCM) solvent. As shown in Figure 3, tetracene 2
(1ꢂ10À5 m) displays three absorption bands at 294, 347, and
366 nm. It exhibits the emission maxima at 564 nm with ex-
citation at 366 nm. The spectra of 2 thin film prepared on
glass slice showed broad absorption from 370 to 440 nm
(Figure S1 in the Supporting Information). Fluorescence
spectra of 2 film on glass slice displayed the bands at 467
and 527 nm. The quantum yield (Ff) of tetracene 2 in DCM
was measured as Ff =45% (9,10-diphenylanthrance as stan-
dard (100%) at 258C).
To test the carrier-transport capability of tetracene 2,
three different organic light-emitting diode (OLED) devices
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Polycyclic Aromatic Hydrocarbons
FULL PAPER
bottom part of Figure 4b. It can be seen that the emission
peak red-shifted as the doping concentration increases. The
peak-shift is followed with a small drop in the EQE. It is
worth mentioning that the EQE is significantly larger than
that of device 1, which utilizes bulk tetracene 2 as the emit-
ter. Utilizing tetracene 2 as a dopant proves to reduce the
aggregation effect and increases the EQE.
Conclusion
In conclusion, a novel and stable tetracene 2 has been suc-
cessfully synthesized and fully characterized. The twisted
feature renders this type of PAH as a potential candidate
for organic electronics. Although the performance of devices
is not as good as we predicted, we have demonstrated the
bipolar transporting ability of 2 in OLEDs. Further work to
construct highly conjugated twisted compounds is under in-
vestigation.
Experimental Section
Materials: All starting materials were used as received without further
purification. Compounds pyrano-diphenylcyclopentadienone (3) was syn-
thesized according to the reported procedure.[17,18]
Figure 4. Top: Current density of OLED devices with tetracene 2 as the
electron-transporting (black squares) and hole-transporting (red circles)
layers. Data for the standard device are shown for comparison (blue tri-
angles). Inset shows the corresponding emission spectra. Bottom: Current
density and luminance of devices with tetracene 2 doped in CBP with
concentrations of 2% (dark squares) and 20% (orange circles). Insets i)
and ii) show the current efficiencies and the emission spectra, respective-
ly, of OLED devices with tetracene 2 utilized as dopant with different
concentrations.
X-ray crystal structure: Single-crystal data set was collected at 250 K on a
Bruker SMART APEX II CCD fitted with graphite monochromatized
MoKa radiation (l=0.71073 ꢁ). Data processing (APEXII[19] and
SMART[19]) and absorption correction (SADABS[20]) were accomplished
by standard methods. The structure was solved by direct-methods using
SHELXS-97[21] and refinement (anisotropic displacement parameters, hy-
drogen atoms in the riding model approximation and a weighting scheme
of the form w=1/[s2(Fo2)+(0.064P)2 +0.376P] for P=(Fo2 +2F2c)/3) was
on F2 by means of SHELXL-97.[18c] The crystal was weakly diffracting, a
feature exacerbated by the crystal shattering at significantly reduced tem-
peratures, and although data was collected to higher values, the crystal
diffracted only to qmax of 24.98. Figure 1 was drawn with ORTEP[22] at the
35% probability level and the remaining crystallographic figures were
drawn with DIAMOND using arbitrary spheres.[23]
0.8% photons per electron, while devices 1 and 2 reach
EQEs of only 0.026% and 0.018%, respectively. The low
EQE may be improved by replacing the two electron-with-
drawing groups (NO2 and COOMe) with electron-donating
groups, research is currently on the way.
Fabrication and evaluation of OLEDs: The ITO (indium-tin-oxide)-glass
was cleaned by using a routine cleaning procedure, which include ultra-
sonication in acetone, followed by ethanol, and rinsing in de-ionized
water. A clean ITO glass exhibited resistance on the order of 50 W per
square. Before deposition, the ITO was treated by oxygen plasma at
10 Pa for 2.5 min. Evaporation of organic materials and metals was car-
ried out under high vacuum conditions (about 2ꢂ10À4 Pa). Electrolumi-
nescence spectra of the fabricated devices were measured with a PR650
Spectra Scan spectrometer. Current-density/voltage characteristics were
recorded by Yokogawa source measurement unit. All measurements
were carried out at room temperature under ambient conditions without
any encapsulation.
Tetracene 2 has also been investigated as an emitter in
OLEDs. Generally, a small amount of tetracene 2 was
doped in a host–guest system (e.g., CBP). OLEDs with
structure of ITO/NPB (50 nm)/CBP:2 (x% wt)/BCP
(20 nm)/Alq3 (20 nm)/Mg:Ag have been fabricated. Here,
CBP is 4,4’-bis(carbazol-9-yl)biphenyl, a common host mate-
rial and BCP is 2,9-dimethyl-4,7-diphenyl-1,10-phenanthro-
line, a common hole-blocking layer. The doping concentra-
tions (x%) of tetracene 2 were 2 and 20%. Figure 4
(bottom) shows current density and luminance versus volt-
age of the corresponding devices. It can be seen that the
voltage increases as the dopant concentration increases,
which indicates that tetracene 2 traps the charges signifi-
cantly. Inset i) of Figure 4 (bottom) shows the current effi-
ciency as a function of current density of the devices. Devi-
ces with dopant concentration of 2 and 20% reach efficiency
of 0.47 and 0.38 CdAÀ1, respectively. The emission spectrum
of the corresponding devices is shown in inset ii) in the
Acknowledgements
Q.Z. thanks the financial support from the NTU start-up grant, X.W.S.
and Y.D. thanks the Singapore Millennium Foundation (SMF) for the fi-
nancial support, and F.W. thanks the NSF for support.
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Q. Zhang, X. W. Sun, F. Wudl et al.
[10] a) F. Liu, L. H. Xie, C. Tang, J. Liang, Q. Q. Chen, B. Peng, W. Wei,
Y. Cao, W. Huang, Org. Lett. 2009, 11, 3850; b) L. H. Xie, X. Y.
Hou, Y. R. Hua, Y. Q. Huang, B. M. Zhao, F. Liu, B. Peng, W. Wei,
W. Huang, Org. Lett. 2007, 9, 1619; c) C. Tang, F. Liu, Y. J. Xia,
L. H. Xie, A. Wei, S. B. Li, Q. L. Fan, W. Huang, J. Mater. Chem.
2006, 16, 4074.
[11] a) L. Turker, A. Tapan, S. Gꢄmꢄs, Polycyclic Aromat. Compd. 2009,
29, 139; b) T. Otsubo, Y. Aso, K. J. Takimiya, J. Mater. Chem. 2002,
12, 2565; c) P. C. Bevilacqua, R. Kierzek, K. A. Johnson, D. H.
Turner, Science 1992, 258, 1355.
[1] a) Y. Geerts, G. Klꢃrner, K. Mꢄllen in Electronic Materials: The
Oligomer Approach (Eds.: K. Mꢄllen, G. Wagner), Wiley-VCH,
ACHTUNGTRENNUNG
Weinheim, 1998; Chapter 1; b) R. G. Havey, Polycyclic Aromatic
Hydrocarbons, Wiley-VCH, New York, 1997.
[2] a) E. Clar, Polycyclic Hydrocarbons, Vol. 1 and 2, Academic Press,
London, 1964; b) E. Clar, The Aromatic Sexet, Wiley, London, 1972;
c) H. Hosoya, Top. Curr. Chem. 1990, 153, 255; d) M. Zander, Poly-
cyclische Aromaten: Kohlenstoffe und Fullerene, Teubner, Stuttgart,
1995.
[3] For recent reviews: a) R. Gleiter, B. Esser, S. C. Kornmayer, Acc.
Chem. Res. 2009, 42, 1108; b) J. E. Anthony, Angew. Chem. 2008,
120, 460; Angew. Chem. Int. Ed. 2008, 47, 452; c) S. Kotha, S. Misra,
S. Halder, Tetrahedron 2008, 64, 10775; d) R. A. Pascal, Jr., Chem.
Rev. 2006, 106, 4809; e) Y. T. Wu, J. S. Siegel, Chem. Rev. 2006, 106,
4843; f) J. E. Anthony, Chem. Rev. 2006, 106, 5028; g) M. Bendikov,
F. Wudl, D. F. Perepichka, Chem. Rev. 2004, 104, 4891.
[4] a) D. Wasserfallen, M. Kastler, W. Pisula, W. A. Hofer, Y. Fogel, Z.
Wang, K. Mꢄllen, J. Am. Chem. Soc. 2006, 128, 1334; b) M. Kastler,
W. Pisula, D. Wasserfallen, T. Pakula, K. Mꢄllen, J. Am. Chem. Soc.
2005, 127, 4286; c) D. W. Breiby, O. Bunk, W. Pisula, T. I. Solling, A.
Tracz, T. Pakula, K. Mꢄllen, M. M. Nielsen, J. Am. Chem. Soc. 2005,
127, 11288; d) W. Pisula, Z. Tomovic, C. Simpson, M. Kastler, T.
Pakula, K. Mꢄllen, Chem. Mater. 2005, 17, 4296; e) W. Pisula, Z.
[12] a) H. Y. Oh, C. Lee, S. Lee, Org. Electronics 2009, 10, 163; b) U.
Mitschke, P. Bauerle, J. Mater. Chem. 2000, 10, 1471.
[13] a) M. Y. Lai, C. H. Chen, W. S. Huang, J. T. Lin, T. H. Ke, L. Y.
Chen, M. H. Tsai, C. C. Wu, Angew. Chem. 2008, 120, 591; Angew.
Chem. Int. Ed. 2008, 47, 581; b) Z. Ge, T. Hayakawa, S. Ando, M.
Ueda, T. Akiike, H. Miyamoto, T. Kajita, M. Kakimoto, Adv. Funct.
Mater. 2008, 18, 584; c) Z. Ge, T. Hayakawa, S. Ando, M. Ueda, T.
Akiike, H. Miyamoto, T. Kajita, M. Kakimoto, Chem. Mater. 2008,
20, 2532.
[14] a) J. Lu, D. M. Ho, N. J. Vogelaar, C. M. Kraml, S. Bernhard, N.
Byrne, L. R. Kim, R. A. Pascal, Jr., J. Am. Chem. Soc. 2006, 128,
17043; b) J. Lu, D. M. Ho, N. J. Vogelaar, C. M. Kraml, R. A. Pas-
cal, Jr., J. Am. Chem. Soc. 2004, 126, 11168; c) I. I. Schuster, L. Cra-
cium, D. M. Ho, R. A. Pascal, Jr., Tetrahedron 2002, 58, 8875; d) J.
Zhang, D. M. Ho, R. A. Pascal, Jr., Tetrahedron Lett. 1999, 40, 3859;
e) X. Qiao, D. M. Ho, R. A. Pascal, Jr., Angew. Chem. 1997, 109,
1588; Angew. Chem. Int. Ed. Engl. 1997, 36, 1531.
TomACHTUNGTRENNUNGovic, M. Stepputata, U. Kolb, T. Pakula, K. Mꢄllen, Chem.
Mater. 2005, 17, 2641.
[5] a) Y. Yang, F. Wudl, Adv. Mater. 2009, 21, 1401; b) J. Cornil, J. L.
Brꢅdas, J. Zaumseil, H. Sirringhaus, Adv. Mater. 2007, 19, 1791; c) J.
Wu, Curr. Org. Chem. 2007, 11, 1220; d) Y. H. Wijsboom, A. Patra,
S. S. Ade, Y. Sheynin, M. Li, L. J. W. Shimon, M. Bendikov, Angew.
Chem. 2009, 121, 5551; Angew. Chem. Int. Ed. 2009, 48, 5443; e) A.
Patra, Y. H. Wijsboom, S. S. Zade, M. Li, Y. Sheynin, G. Leitus, M.
Bendikov, J. Am. Chem. Soc. 2008, 130, 6734.
[15] a) Q. Xu, H. M. Duong, F. Wudl, Y. Yang, Appl. Phys. Lett. 2004,
85, 3357; b) H. M. Duong, M. Bendikov, D. Steiger, Q. Zhang, G.
Sonmez, J. Yamada, F. Wudl, Org. Lett. 2003, 5, 4433.
[16] a) CCDC-744864 (2) contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.
[6] a) L. B. Roberson, J. Kowalik, L. M. Tolbert, C. Kloc, R. Zeis, X.
Chi, R. Flemming, C. Wilkins, J. Am. Chem. Soc. 2005, 127, 3069;
b) V. De Halleux, J. P. Calbert, P. Brocorens, J. Cornil, J. P. Declercq,
J. L. Brꢅdas, Y. Geerts, Adv. Funct. Mater. 2004, 14, 649; c) L.
Schmidt-Mende, A. Fenchtenkçtter, K. Mꢄllen, E. Moons, R. H.
Friend, J. D. MacKenzie, Science 2001, 293, 1119; d) C. J. Brabec,
N. S. Sariciftci, J. C. Hummelen, Adv. Funct. Mater. 2001, 11, 15;
e) A. M. Van de Craats, J. M. Warman, Adv. Mater. 2001, 13, 130;
f) C. Y. Liu, A. Bard, J. Chemother. 2000, 12, 2353.
ac.uk/data_request/cif. Details of the intermolecular interactions;
i
b) C18 H18···O1 =2.34 ꢁ, C18···O1i =3.260(3) ꢁ, with an angle
À
subtended at H18 of 1668 for symmetry operation i: 1+x, y, z;
ii
À
c) C14 H14···Cg(C25–C30) =2.72 ꢁ,
C14···Cg(C25–C30)ii =
3.587(3) ꢁ, with angle at H14 of 1548 for symmetry operation ii:
2Àx, 1Ày, 1Àz.
[17] a) T. Kappe, D. Pocivalnik, Heterocycles 1983, 20, 1367; b) C. Held-
mann, M. Schulze, G. Wegner, Macromolecules 1996, 29, 4686;
c) H. M. Duong, Ph.D. Thesis (UCLA), 2003.
[7] a) M. L. Tang, S. C. B. Mannsfeld, Y. S. Sun, H. A. Becerril, Z. Bao,
J. Am. Chem. Soc. 2009, 131, 882; b) M. L. Tang, A. D. Reichardt, T.
Siegrist, S. C. B. Stefan, Z. Bao, Chem. Mater. 2008, 20, 4669; c) A.
Dadvand, F. Cicoira, C. Fabio, Y. Konstantin, E. S. Balenkova, R. M.
Osuna, F. Rosei, V. G. Nenajdenko, D. F. Perapichka, Chem.
Commun. 2008, 5354; d) M. M. Payne, S. R. Parkin, R. Sean, J. E.
Anthony, J. Am. Chem. Soc. 2005, 127, 8028; e) Z. Bao, Adv. Mater.
2000, 12, 227.
[8] a) D. Chun, Y. Cheng, F. Wudl, Angew. Chem. 2008, 120, 8508;
Angew. Chem. Int. Ed. 2008, 47, 8380; b) H. Wang, C. Schaffner-
Hamann, F. Marchioni, F. Wudl, Adv. Mater. 2007, 19, 558.
[9] A. S. Paraskar, A. R. Reddy, A. Patra, Y. H. Wijsboom, O. Gidron,
L. J. W. Shimon, G. Leitus, M. Bendikov, Chem. Eur. J. 2008, 14,
10639.
[18] R. A. Pascal, Jr., W. D. McMillan, D. Van Engen, R. G. Eason, J.
Am. Chem. Soc. 1987, 109, 4660.
[19] Bruker AXS Inc. APEX2 and SAINT software, Bruker AXS Inc.,
Madison, Wisconsin, 2009.
[20] G. M. Sheldrick, SADABS. University of Gçttingen, Gçttingen,
1996.
[21] G. M. Sheldrick, Acta Crystallogr. Sect. A 2008, 64, 112.
[22] L. J. Farrugia, J. Appl. Crystallogr. 1999, 32, 837.
[23] DIAMOND, Visual Crystal Structure Information System, Ver-
sion 3.1, CRYSTAL IMPACT, Postfach 1251, 53002 Bonn, Germany,
2006.
Received: January 6, 2010
Published online: May 12, 2010
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