Long-range self-assembly of bis(imidazole)-annulated terphenyls

Article abstract of DOI:10.1039/b608593h

In our study, we present the synthesis and characterisation of the first bis(imidazole)-annulated terphenyl disc-shaped molecules, which self-organise into columnar structures throughout long-range ordered domains during cooling from the isotropic phase. Two derivatives substituted with 3,7-dimethyloctyl and 2-decyltetradecyl substituents have been prepared. Concentration dependent UV/vis investigations indicated pronounced aggregation of both compounds in solution. The structural analysis of mechanically aligned samples revealed columnar supramolecular order with favoured helical stacking of the discs with a pitch of four molecules independent of the substituents. On the other hand, significant differences in the self-organisation during solidification from the isotropic phase were observed. The bulkier the alkyl side chains, the lower the growth rate and the higher the macroscopic order of the domains. These novel bis(imidazole)-annulated terphenyls are promising candidates for field-effect transistor applications because of the pronounced molecular packing and the formation of macroscopically aligned domains with edge-on arranged molecules. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b608593h

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PAPER
www.rsc.org/materials | Journal of Materials Chemistry
Long-range self-assembly of bis(imidazole)-annulated terphenyls
Wojciech Pisula, Frank Dierschke and Klaus Mu¨llen*
Received 16th June 2006, Accepted 18th August 2006
First published as an Advance Article on the web 30th August 2006
DOI: 10.1039/b608593h
In our study, we present the synthesis and characterisation of the first bis(imidazole)-annulated
terphenyl disc-shaped molecules, which self-organise into columnar structures throughout long-
range ordered domains during cooling from the isotropic phase. Two derivatives substituted with
3,7-dimethyloctyl and 2-decyltetradecyl substituents have been prepared. Concentration
dependent UV/vis investigations indicated pronounced aggregation of both compounds in
solution. The structural analysis of mechanically aligned samples revealed columnar
supramolecular order with favoured helical stacking of the discs with a pitch of four molecules
independent of the substituents. On the other hand, significant differences in the self-organisation
during solidification from the isotropic phase were observed. The bulkier the alkyl side chains, the
lower the growth rate and the higher the macroscopic order of the domains. These novel
bis(imidazole)-annulated terphenyls are promising candidates for field-effect transistor
applications because of the pronounced molecular packing and the formation of macroscopically
aligned domains with edge-on arranged molecules.
and non-polar substituents.11 Here we present the synthesis
Introduction
of the first bis(imidazole)-annulated terphenyl as a planar
disc-shaped building block and its self-assembly into long-
ranged columnar superstructures when processed from the
melt. The observed pronounced intracolumnar packing of
these molecules and the formation of well-ordered and large
domains are desired for the implementation of discotic
materials in FET devices.
Organic semiconductors have gained increasing attention in
the development of electronic devices.1 One advantage of
organic conjugated polymeric materials is the ease with which
they can be processed at low cost.2,3 However, since the long-
range order between the electrodes is essential for undisturbed
charge carrier transport, many polymer-based field-effect
transistors (FETs) demonstrated relatively poor performance
due to the high disorder of the conjugated polymer chains. It
has been shown previously that discotic liquid crystals are
promising alternatives for use in electronics because of their
ability to self-organise into highly ordered superstructures via
p-interactions.4 In these structures the molecules assemble into
columnar arrays which form a percolation pathway for
electrons and holes.5 High charge carrier mobilities along the
one-dimensional stacks have been measured with values of up
to 1.1 cm2 V s21.6 The variation of the core substitution allows
fine tuning of the bulk properties and processibility of these
materials from solution or from the isotropic phase.7 A major
advantage of discotics is the formation of a liquid crystalline
phase which promotes self-healing of macroscopic defects.8 In
contrast to other organic semiconductors, it is also possible to
control the organisation of the disc-shaped molecules on
surfaces. Thereby, the discs can arrange themselves in an edge-
on manner, which is important in FETs,9 or face-on, leading to
a homeotropic phase,10 which is required in photovoltaic cells.
It has been reported that the formation of complex super-
structures of liquid crystalline terphenyls can be successfully
tailored by the nature and the position of the substituents.11
These ternary block molecules self-organised due to a nano-
separation between the rigid terphenyl unit and flexible polar
Results and discussion
Most of the previously described heteroaromatic discotic
materials have been prepared either by condensation reactions
or by oxidative cyclodehydrogenation of suitable precursor
materials.7a,12 Here, the palladium-catalysed intramolecular
amination of chlorinated terphenyls 6a/b with two imidazole
substituents to give the planarised polycyclic compounds 1a/b
(Scheme 1) is demonstrated. The terphenyl core 4 was synthe-
sised by a Suzuki coupling of dibromoterephthaldehyde (2)
with 2-chlorobenzene-boronic acid (3) to yield the dichloro-
terphenyl 4. To introduce solubility and phase formation, alkyl
chains were introduced into the side-groups of the discotic
material by alkylation of 4,49-dihydroxybenzil with 3,7-
dimethyloctylbromide and 2-decyltetradecylbromide. The
imidazole rings of 6a and 6b were generated by condensation
of the aldehyde groups of 4 with the benzil functionalities of 5a
and 5b, respectively. This reaction was performed with
ammonium acetate, as an ammonia source, in acetic acid.
The molecules 6a and 6b were planarised successfully by an
intramolecular Buchwald-type reaction.13 The intramolecular
C–N bond formation using palladium(II) acetate, triethylphos-
phine and sodium tert-butoxide proceeded in 87% and 72%
yield to produce 1a and 1b respectively. This catalyst system
was utilised, as the use of bulky ligands like 2-(di-tert-
butylphosphino)biphenyl did not lead to product formation.
Max-Planck-Institute for Polymer Research, Ackermannweg 10,
D-55128, Mainz, Germany. E-mail: muellen@mpip-mainz.mpg.de;
Fax: +49 6131 379350; Tel: +49 6131 379150
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Scheme 1 Synthetic route toward the planarised bis(imidazoles) 1a and 1b.
Due to their identical core structure, both compounds (1a
and 1b) exhibited identical UV/vis spectra in solution (THF)
with a well resolved vibronic structure (Fig. 1). The absorption
maxima of 1a were located at 328 nm, 342 nm, 370 nm and
384 nm, which were the same as the maxima of 1b. In
comparison, the open precursors 6a and 6b showed only broad
absorption bands with maxima at 377 nm, indicating a less
rigid chromophore. The photoluminescence spectra of 1a and
1b at high concentrations (20 mmol L21 and 11.6 mmol L21
respectively) revealed broad emission bands with maxima at
468 nm and 467 nm respectively and a vibrational sideband
at 447 nm. As the concentration of 1b was decreased from
11.6 mmol L21 to 0.12 mmol L21, a new sharp fluorescence
band appeared at 416 nm. Similarly, an additional fluorescence
band appeared at 417 nm for 1a when the concentration was
reduced from 20 mmol L21 to 0.2 mmol L21. The vibronic
features and the missing hypsochromic shift of the low energy
band at lower concentrations suggests that the changes in the
photoluminescence spectra did not originate from aggregation.
The reason for the additional high energy band at low
concentration remains unclear, but we speculate that this high
energy band might be due to a transition from a higher
vibrational level (v . 0) of the first excited state S1 into the
vibrational levels of the ground state S0.
The differential scanning calorimetry (DSC) scans for both
compounds (1a and 1b), Fig. 2, revealed only one phase transi-
tion from the columnar phase to the isotropic state. The small
exothermic cold-crystallisation peak prior to the main endo-
thermic one was attributed to a supercooling of the sample.14
The isotropisation temperature decreased from 162 uC
(DH2nd heating = 32.0 J g21) for 1a to 114 uC (DH2nd heating
=
5.7 J g21) for 1b with increasing steric demand of the dove-
tailed side chains. Furthermore, the enthalpy decrease of the
phase transition indicated a lowering of the order in the solid
phase by the introduction of longer alkyl substituents. Addi-
tionally, 1a and 1b exhibit high thermal stability up to 350 uC.
Two-dimensional wide-angle X-ray diffraction (2D-WAXS)
experiments were performed on an extruded fibre to
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Fig. 3 2D-WAXS patterns of 1a and 1b prepared by filament
extrusion.
pffiffi
fitted to the characteristic correlation of 1 : 2 : 2 (see Table 1).
Packing parameters of a = 2.76 nm for 1a and of a = 2.86 nm for
1b were found to be dependent on the length of the side chains.
Strong meridional wide-angle reflections at 0.38 nm for 1a and
0.45 nm for 1b correspond to face-to-face distances between the
disc-shaped molecules and indicate an orthogonal arrangement of
their molecular planes relative to the columnar axis. The alkyl
chain correlation is in the same range, but appears as an
amorphous halo in the X-ray pattern. Middle-range meridional
reflections relating to periodicities of 1.82 nm for 1a and 2.16 nm
for 1b suggest additional intracolumnar correlations between every
5th disc (for 1b 2.16/0.45 y 5). Further multiple meridional
reflections confirm a helical arrangement of the molecules along
the columns (see Table 1).16 This helical organisation was formed
by a slight rotation of each disc relative to each other, induced by
the high steric hindrance of the phenyl rings attached at the
corona. In general, a helical arrangement of discotics enhances the
molecular packing, leading to higher charge carrier mobilities
along the columnar structures.4
Fig. 1 UV and PL spectra of 1a and 1b and UV spectra of the
precursors 6a and 6b (THF).
On the basis of the X-ray results, 1a was a crystalline powder
in its solid phase. The phase characterisation of 1b was less
clear. Whereas 1b was waxy and soft at room temperature,
which is characteristic for a mesophase, the rather complex
intracolumnar organisation of this material excluded its
classification as a liquid crystalline phase. Therefore, com-
pound 1b was considered to be plastic crystalline.17
investigate the supramolecular structure of the self-assembled
molecules (Fig. 3).15 The 2D lateral tetragonal unit cells,
describing the intercolumnar organisation, were assigned from
the positions of the sharp equatorial reflections, which were
The accessible isotropisation temperature of both com-
pounds allowed the investigation of the self-assembly from the
melt by polarised optical microscopy (POM) at different
cooling rates. Close to the crystallisation temperature of 1a,
well-ordered spherulites nucleated randomly over the whole
Table 1 Miller indices (hkl) and d-spacings (nm) from 2D-WAXS of
extruded fibres. The calculated values are given in brackets
1a
1b
Equatorial reflections
100
110
200
120
2.76 (2.76)
1.90 (1.96)
1.35 (1.39)
1.19 (1.24)
2.86 (2.86)
2.08 (2.02)
1.43 (1.43)
—
Meridional reflections
hk1
hk2
hk3
hk4
1.82
0.95
0.63
0.38
2.16
1.13
0.74
0.45
Fig. 2 DSC scans of 1a and 1b during first cooling and second
heating (10 uC min21). Arrows indicate the cooling and heating
directions.
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Fig. 4 Cross-polarised optical microscopy images and schematic illustrations of the supramolecular organisations in the structures of a) 1a and b)
1b after non-isothermal cooling at rates of 1 uC min21 and 0.1 uC min21, respectively. The arrows in the drawings represent the assembly directions
of the columns during solidification. The samples were prepared between two glass slides.
sample area (Fig. 4a). The high optical anisotropy and the
appearance of the Maltese cross indicate pronounced macro-
scopic order. The extinction along the analyser/polariser
direction suggests
a radial alignment of the columnar
structures from the centre and an edge-on arrangement of
the molecules.18 The atomic force microscopy (AFM) image
confirmed this assumption, revealing the topography of the
spherulites with growth structures that expanded radially from
the nucleation centre (Fig. 5b). Recently, structural studies of
spherulites, formed by disc-shaped molecules self-assembled
into columnar structures, by using microfocus synchrotron
radiation verified the analysis of the POM and AFM
experiments.19 The study of the crystallisation kinetics showed
a maximum growth rate at 130 uC, at which domains with sizes
of several hundred micrometres were obtained (Fig. 5a). A
comparison to the growth rate of polymers is not possible in
this case due to significant differences between both systems in
macroscopic organisation. In contrast, during slow cooling 1b
formed long and highly birefringent ‘‘quasi-crystalline’’ fibres
with lengths exceeding several millimetres (Fig. 4b), in which
the columns were oriented uniaxially along the fibre axes. The
observed morphology indicated a great tendency of 1a and 1b
to self-organise over macroscopic dimensions. In comparison,
discotic hexa-peri-hexabenzocoronenes and perylenetetra-
carboxydiimides, substituted by short aliphatic side chains,
form smaller and less ordered domains with defect structures
which possess low uniform birefringence in the POM.20 The
bulkier the alkyl substituents, the weaker the interaction
between the molecules, resulting in a lower growth rate and
thus in the establishment of domains with improved long-
range order.
Fig. 5 a) Spherulite growth kinetics of 1a based on isothermal
crystallisation and b) topography image from AFM of 1a after
crystallisation from the isotropic phase (the image was taken in
tapping mode).
In conclusion, we have developed a new discotic material
based on a planar bis(imidazole)-annulated terphenyl, with
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good solubility and a low isotropisation temperature, allowing
facile processibility. The self-assembly took place via p-stack-
ing of the rigid cores into columnar superstructures. The
compounds 1a and 1b showed, independent of the alkyl
substituents, favourable helical packing within the columns,
which is considered to enhance the one-dimensional charge
carrier transport. Additionally, 1a and 1b revealed pronounced
self-assembly into well-oriented structures over macroscopic
dimensions due to directional growth of the material when
processed from the melt. In principle, the distance between the
electrodes in a device of several tenths of micrometres can be
spanned by these ‘‘self-aligned’’ highly ordered supramolecular
structures, making the novel bis(imidazole)-annulated terphe-
nyls promising candidates for electronic applications.
and then quenched with HCl (2 M). The mixture was extracted
with dichloromethane and the organic fractions were dried
with MgSO4. The solvent was removed under reduced pressure
and the product was purified by column chromatography (10%
ethyl acetate in hexane) and subsequent recrystallisation from
ethanol to provide 782 mg (72%) of the title product as a
1
yellow solid, mp 217 uC. H NMR (250 MHz, CD2Cl2): d =
9.89 (s, 2H), 7.99 (s, 2H), 7.55 (m, 8H). 13C NMR (75.46 MHz,
CD2Cl2): d = 190.86, 142.46, 137.22, 135.96, 133.70, 132.14,
130.67, 130.51, 130.06, 127.66. Anal. Calcd for C20H12Cl2O2:
C, 67.63; H, 3.41. Found: C, 67.49; H, 3.43.
4,49-Bis(3,7-dimethyloctyloxy)benzil (5a)
4,49-Dihydroxybenzil (4 g, 16.5 mmol) and K2CO3 (4.58 g,
33.1 mmol) were dissolved in DMF (30 mL) and stirred for
30 min at RT. 3,7-Dimethyloctylbromide (8.05 g, 36.4 mmol)
was added and the reaction mixture was stirred for 3 days at
80 uC. The reaction was quenched by the addition of water and
the products extracted with dichloromethane. The organic
fractions were dried over MgSO4 and the solvent was removed
under reduced pressure. The product was purified by column
chromatography (5% ethyl acetate in hexane) to give the title
compound as a yellow oil (5.51 g, 64%). FD-MS: m/z =
The authors acknowledge financial support from the
Deutsche Forschungsgemeinschaft (Schwerpunkt Feldeffekt-
transistoren) and EU project NAIMO Integrated Project No.
NMP4-CT-2004-500355.
Experimental
General methods
1H and 13C NMR spectra were recorded on a Bruker DPX 250
or Bruker AMX 300 with the solvent residual proton or
carbon signal as the internal standard. Melting points were
determined on a Bu¨chi hot stage apparatus and are not
corrected. Mass spectra were obtained on a VG Instruments
ZAB 2-SE-FPD by using field desorption (FD). Elemental
analyses were carried out on a Foss Heraeus Vario EL. All
starting materials were used as purchased from commercial
sources. The solvents were dried following standard proce-
dures. 2,5-Dibromoterephthalaldehyde (2) and 4,49-dihydroxy-
benzil were synthesised according to literature procedures.
UV/vis and PL spectra were recorded using a Perkin–Elmer
Lambda 9 spectrophotometer and SPEX Fluorolog 2 type
F212 spectrometer, respectively.
1
522.8 [M+] (calcd 522.78), H NMR (250 MHz, CD2Cl2): 7.91
(d, J = 8.8 Hz, 4H), 6.98 (d, J = 9.1 Hz, 4H), 4.08 (t, J =
5.95 Hz, 4H, OCH2), 1.85–1.16 (m, 20H), 0.88 (m, 18H, CH3).
13C NMR (75.46 MHz, CD2Cl2): d = 193.97, 164.98, 132.57,
126.43, 115.11, 67.37, 39.61, 37.59, 36.30, 30.22, 28.38, 25.03,
22.83, 22.73, 19.76.
4,49-Bis(2-decyltetradecyloxy)benzil (5b)
4,49-Dihydroxybenzil (6 g, 24.7 mmol), K2CO3 (6.85 g,
49.56 mmol), DMF (40 mL) and 2-decyltetradecylbromide
(22.75 g, 54.5 mmol) were treated in the same way as for
compound 5a. The product was purified by column chroma-
tography (5% ethyl acetate in hexane) to give the title
compound as a yellow oil 18.54 g (y81%). m/z = 916.5 [M+]
(calcd 915.53). 1H NMR (250 MHz, CD2Cl2): d = 7.91 (d, J =
8.78 Hz, 4H), 8.98 (d, J = 8.8 Hz, 4H), 3.93 (d, J = 5.65 Hz,
4H), 1.80 (m, 2H), 1.26 (m, 80H), 0.87 (t, J = 5.95 Hz, 12H).
13C NMR (75.46 MHz, CD2Cl2): d = 194.01, 165.22, 132.54,
126.38, 115.12, 71.84, 38.20, 32.32, 31.61, 30.34, 30.06, 30.03,
29.98, 29.74, 27.15, 23.08, 14.26.
DSC was performed using a Mettler DSC 30 apparatus with
a heating rate of 10 K min21 from 2100 uC to 250 uC for 1a,
and from 220 uC to 200 uC for 1b. The optical textures of the
compounds were investigated using a Zeiss microscope with
polarising filters equipped with a Hitachi KP-D50 colour
digital CCD camera. The samples were sandwiched between
two glass slides and then thermally treated on a Linkam hot
stage regulated with a Linkam TMS 91 temperature controller.
The topography images were obtained in tapping mode by
atomic force microscopy (AFM) using a Digital Instruments
Nanoscope IIIa MultiMode scanning probe microscope.
The 2D-WAXS experiments were performed by means of a
rotating anode (Rigaku 18 kW) X-ray beam with pinhole
collimation and a 2D Siemens detector. A double graphite
monochromator for the Cu-Ka radiation (l = 0.154 nm)
was used.
2,20-Dichloro-29,59-bis(4,5-bis(4-(3,7-dimethyloctyl)phenyl)
imidazol-2-yl)-[1,19,49,10]terphenyl (6a)
Benzil 5a (1.91 g, 3.66 mmol), 4 (500 mg, 1.41 mmol),
ammonium acetate (1.54 g, 54 mmol) and conc. acetic acid
(30 mL) were heated at 120 uC for 18 h under argon. After the
reaction was cooled, ice (50 mL) was added and the mixture
was made basic with aqueous ammonia. The solution was
extracted with dichloromethane and dried over MgSO4. The
solvent was removed under reduced pressure and the product
was purified by column chromatography (10% ethyl acetate in
hexane) to give the title compound as a yellow solid (1.42 g,
2,20-Dichloro-[1,19,49,10]terphenyl-29,59-dicarbaldehyde (4)
2-Chlorophenylboronic acid (1 g, 6.3 mmol), 2 (888 mg,
3.04 mmol) and Pd(PPh3)4 (73 mg, 0.063 mmol) were dissolved
in a degassed mixture of aqueous K2CO3 (2 M, 16 mL) and
THF (48 mL). The reaction was stirred under reflux for 48 h
1
74%). m/z = 1360.5 [M+] (calcd 1360.8). H NMR (250 MHz,
CD2Cl2): d = 8.31 (m, 2H), 8.14 (d, J = 5.35 Hz, 2H), 7.55
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(m, 12H), 6.95 (d, J = 8.47 Hz, 4H), 6.77 (d, J = 7.22 Hz, 8H),
3.97 (m, 8H, OCH3), 1.81–1.17 (m, 40H), 0.87 (m, 36H, CH3).
13C NMR (75.46 MHz, C2D2Cl4, 100 uC): d = 158.93, 143.83,
140.16, 135.85, 134.42, 132.04, 130.73, 130.49, 130.13, 128.93,
128.84, 127.91, 115.24, 67.18, 39.56, 37.63, 36.64, 30.40, 28.12,
24.81, 22.81, 22.75, 19.98. Anal. Calcd for C88H112Cl2N4O4: C,
77.67; H, 8.30; N, 4.12. Found: C, 77.70; H, 8.34; N, 4.26.
by column chromatography (5% ethyl acetate in hexane) to
provide 474 mg (72%) of 1b as a yellow wax. m/z = 2073.7 [M+]
(calcd 2073.4). 1H NMR (250 MHz, CD2Cl2): d = 9.48 (s, 2H),
8.52 (d, J = 9.15 Hz, 2H), 7.50 (d, J = 8.53 Hz, 4H), 7.26
(m, 6H), 7.06 (m, 6H), 6.78 (d, J = 8.53 Hz, 4H), 3.92 (m, 4H,
ArOCH2), 3.71 (m, 4H, ArOCH2), 1.81 (br s, 4H, alkyl),
1.19 (br s, 160H, alkyl), 0.81 (m, 24H, CH3). 13C NMR
(62.89 MHz, CD2Cl2): d = 160.67, 159.01, 142.27, 141.65,
134.40, 133.20, 129.18, 128.07, 127.49, 125.40, 125.18, 125.09,
124.97, 124.12, 122.82, 118.20, 117.87, 115.97, 114.46, 71.63,
71.34, 38.49, 38.41, 32.33, 31.81, 31.75, 30.46, 30.09,
30.06, 29.77, 27.34, 27.26, 23.09, 14.27. Anal. Calcd for
C144H222N4O4: C, 83.42; H, 10.79; N, 2.70. Found: C, 83.21;
H, 10.90; N, 2.79.
2,3,11,12-Tetrakis(4-(3,7-dimethyloctyl)phenyl)imidazo[1,2-
f]imidazo[19,29:1,2]quino[4,3-j]phenanthridine (1a)
To a mixture of compound 6a (0.5 g, 0.36 mmol) and NaOtBu
(99 mg, 1.03 mmol) in degassed toluene (10 mL) was added,
under argon, palladium acetate (4 mg, 0.018 mmol) and
triethylphosphine (0.55 mL, 1 M in THF). The reaction was
stirred at 115 uC (oil bath) for 48 h and then quenched with
HCl (2 M). The solution was extracted with dichloromethane
and dried over MgSO4. The solvent was removed under
reduced pressure and the product was purified by column
chromatography (10% ethyl acetate in hexane) to provide
411 mg (87%) of 1a as a yellow solid. m/z = 1287.4 [M+] (calcd
1287.88). 1H NMR (250 MHz, CD2Cl2): d = 9.68 (s, 2H), 8.78
(d, J = 7.53 Hz, 2H), 7.57 (d, J = 8.0 Hz, 4H), 7.38 (m, 8H),
7.22 (t, J = 8.15 Hz, 2H), 7.10 (d, J = 8.8 Hz, 4H), 6.82 (d, J =
8.77 Hz, 4H), 4.13 (m, 4H, OCH3), 2.98 (m, 4H, OCH3),
1.94–1.18 (m, 40H), 1.02–0.89 (m, 36H, CH3). 13C NMR
(75.46 MHz, C2D2Cl4, 100 uC): d = 160.40, 158.72, 142.22,
141.51, 134.21, 133.24, 131.87, 129.17, 128.63, 127.97, 127.57,
125.33, 125.27, 124.88, 124.01, 122.77, 118.10, 117.80, 115.91,
114.40, 67.00, 66.72, 39.69, 39.67, 37.76, 37.72, 36.69, 30.38,
30.35, 28.42, 28.40, 25.11, 25.07, 22.88, 22.86, 22.79, 22.76,
19.91, 19.84. Anal. Calcd for C88H110N4O4: C, 82.07; H, 8.61;
N, 4.35. Found: C, 82.13; H, 8.81, N, 4.30.
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and K. Mu¨llen, Adv. Funct. Mater., 2005, 15, 893; E. Grelet and
H. Bock, Europhys. Lett., 2006, 73, 712; K. Hatsusaka, K. Ohta,
I. Yamamoto and H. Shirai, J. Mater. Chem., 2001, 11, 423.
11 B. Chen, X.-B. Zeng, U. Baumeister, G. Ungar and C. Tschierske,
Science, 2005, 307, 96; B. Chen, X.-B. Zeng, U. Baumeister,
S. Diele, G. Ungar and C. Tschierske, Angew. Chem., Int. Ed.,
2004, 43, 4621; B. Chen, U. Baumeister, G. Pelzl, M. Kumar Das,
X. Zeng, G. Ungar and C. Tschierske, J. Am. Chem. Soc., 2005,
127, 16578.
12 G. Kestemont, V. Halleux, M. Lehmann, D. Ivanov, M. Watson
and Y. Geerts, Chem. Commun., 2001, 2074.
13 J. P. Wolfe, H. Tomori, J. P. Sadighi, J. J. Yin and S. L. Buchwald,
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14 Z. Bashir and N. Khan, Thermochim. Acta, 1996, 276, 145;
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molecules, 2005, 6, 244.
15 W. Pisula, Z. Tomovic, C. D. Simpson, M. Kastler, T. Pakula and
K. Mu¨llen, Chem. Mater., 2005, 17, 4296.
2,20-Dichloro-29,59-bis(4,5-bis(4-(2-decyltetradecyl)phenyl)
imidazol-2-yl)-[1,19,49,10]terphenyl (6b)
Benzil 5b (3.35 g, 3.66 mmol), 4 (0.2 g, 0.56 mmol), ammonium
acetate (1.54 g, 54 mmol) and conc. acetic acid (15 mL) were
treated in the same way as for compound 6a. The product
was purified by column chromatography (5% ethyl acetate in
hexane) to give the title compound as a yellow solid (515 mg,
43%). m/z = 2144.3 [M+] (calcd 2146.32), 1H NMR (250 MHz,
C2D2Cl4): d = 8.17–6.74 (m, 24H), 3.73 (d, J = 5.05 Hz, 8H),
1.68 (m, 4H), 1.18 (br s, 160H), 0.79 (t, J = 6.63 Hz, 24H).
13C NMR (75.46 MHz, CD2Cl2):
d = 159.30, 143.73,
140.14, 135.86, 134.40, 132.06, 130.77, 130.49, 130.16,
128.83, 127.94, 115.26, 72.06, 38.47, 32.06, 31.89, 30.19,
29.80, 29.77, 29.43, 27.16, 22.77, 14.14. Anal. Calcd for
C144H224Cl2N4O4: C, 80.58; H, 10.52; N, 2.61. Found:, 80.06;
H, 10.98; N, 2.76.
2,3,11,12-Tetrakis(4-(2-decyltetradecyl)phenyl)imidazo[1,2-
f]imidazo[19,29:1,2]quino[4,3-j]phenanthridine (1b)
16 E. Fontes, P. A. Heiney and W. H. Dejeu, Phys. Rev. Lett., 1988,
61, 1202; S.-H. Jung, W. Pisula, A. Rouhanipour, H. J. Ra¨der,
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F. Nolde, W. Pisula, S. Mu¨ller, C. Kohl and K. Mu¨llen, Chem.
Mater., 2006, 18, 3715.
To a mixture of 6b (340 mg, 0.158 mmol) and NaOtBu (43 mg,
0.44 mmol) in degassed toluene (7 mL) under argon was added
palladium acetate (y2 mg, 8 6 1026 mol) and triethylphos-
phine (0.24 mL, 1 M in THF). The reaction was performed in a
similar way to that for compound 1a. The product was purified
17 A. Bayer, S. Zimmermann and J. H. Wendorff, Mol. Cryst. Liq.
Cryst., 2003, 396, 1.
This journal is ß The Royal Society of Chemistry 2006
J. Mater. Chem., 2006, 16, 4058–4064 | 4063

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S. Baluschev, M.-C. Garcia-Gutierrez, D. Wasserfallen,
H.-J. Butt, C. Riekel, G. Wegner and K. Mu¨llen, Adv. Mater.,
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4064 | J. Mater. Chem., 2006, 16, 4058–4064
This journal is ß The Royal Society of Chemistry 2006