Synthesis and mesomorphism of triphenylene-based dimers with a highly ordered columnar plastic phase

Article abstract of DOI:10.1039/c3tc31986e

A series of triphenylene-based discotic dimers have been synthesized, each of the triphenylene nuclei bears five β-OC₄H₉ substituents, which are linked through the remaining β-positions by a flexible O(CH₂)_nO polymethylene chain (n = 2-12). Their chemical structures were confirmed by proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, high-resolution mass spectrometry and elemental analysis. The mesomorphic properties of these compounds were investigated by differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. It was found that these dimers for which n > 4 formed a highly ordered columnar plastic phase and some of them (n = 6, 7, 10, 11, and 12) exhibited multiple mesophases. This is the first time that the rectangular columnar plastic phase was defined by us as a novel liquid crystal phase of compound 4d (n = 5). The introduction of a single interconnecting chain between adjacent molecules does not significantly perturb the formation of a columnar plastic phase but enriches the mesophases of discotic molecules and hinders the crystallization; the mesophases of 4e-k (n = 6-12) can be supercooled into a glass state in which the self-assembly columnar structures are retained.

Full text of DOI:10.1039/c3tc31986e

Journal of
Materials Chemistry C
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PAPER
Synthesis and mesomorphism of triphenylene-
based dimers with a highly ordered columnar
plastic phase†
Cite this: J. Mater. Chem. C, 2014, 2,
667
1
Yifei Wang, Chunxiu Zhang,* Hao Wu and Jialing Pu
A series of triphenylene-based discotic dimers have been synthesized, each of the triphenylene nuclei bears
4 9 2 n
five b-OC H substituents, which are linked through the remaining b-positions by a flexible O(CH ) O
polymethylene chain (n ¼ 2–12). Their chemical structures were confirmed by proton nuclear magnetic
resonance spectroscopy, Fourier transform infrared spectroscopy, high-resolution mass spectrometry
and elemental analysis. The mesomorphic properties of these compounds were investigated by
differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction. It was found that
these dimers for which n > 4 formed a highly ordered columnar plastic phase and some of them (n ¼ 6,
7
, 10, 11, and 12) exhibited multiple mesophases. This is the first time that the rectangular columnar
plastic phase was defined by us as a novel liquid crystal phase of compound 4d (n ¼ 5). The introduction
of a single interconnecting chain between adjacent molecules does not significantly perturb the
formation of a columnar plastic phase but enriches the mesophases of discotic molecules and hinders
the crystallization; the mesophases of 4e–k (n ¼ 6–12) can be supercooled into a glass state in which
the self-assembly columnar structures are retained.
Received 9th October 2013
Accepted 4th December 2013
DOI: 10.1039/c3tc31986e
www.rsc.org/MaterialsC
the difficulty of synthesis, purication and alignment, which
considerably limiting their practical applications. The forma-
Introduction
Discotic liquid crystals are an emerging class of organic semi- tion of highly ordered columnar phases seems to offer a perfect
conductors. The discs stack on top of each other and arrange in strategy for improving applicable materials, since the mobilities
ꢀ
3
2
ꢀ1 ꢀ1
columnar phases, maximizing the p-orbital overlap between exceeding 10 cm V
s
can be easily achieved by simple
adjacent molecules and thus favouring a one-dimensional charge molecules in their highly ordered columnar phase, such
1–4
transport along the column. These unique electronic proper- as hexahexylthiotriphenylene (HTT6) and hexabutyloxy-
ties together with their solubility make them promising materials triphenylene (HAT4). These molecules are relatively easy to
5–8
for low cost solution processing organic electronic devices.
Since D. Haarer's seminal report on the photoconductivity of fabrication.
synthesize and also less complex when handling for device
the discotic liquid crystal hexahexylthiotriphenylene (HTT6),
A columnar plastic phase is highly appealing as one of the
charge carrier transport in columnar liquid crystals has turned highly ordered phases. It is reported to have a three-dimen-
into one of the most active elds in organic semiconducting sional positional order, as in a crystalline state, while main-
9
–12
ꢀ2
ꢀ1
2
ꢀ1 ꢀ1
materials.
Mobilities of the order of 10 to 10 cm V
s
taining the rotational mobility, thus dened as a columnar
16,17
are reported in columnar mesophases, which are comparable to plastic phase.
Besides the three-dimensional order, this
2,3
those of organic single crystals. These remarkable high phase is very closely related to the normal columnar phase, they
mobilities are generally obtained either from molecules with share similar character of uidity and no major differences in
large aryl cores such as hexabenzocoronenes and phthalocya- structure and dynamics are observed. But the charge mobility of
nines or from the molecules which can form the highly ordered the columnar plastic phase can reach the order of 10 cm V
columnar phases, for instance, the helical phase and the
ꢀ2
2
ꢀ1
ꢀ
1
s
which is about an order of magnitude higher than that of
13–19
13,16,17
columnar plastic phase.
However, large rigid cores increase the normal columnar phase.
However, these minor
changes can highly affect the packing and transport properties
which is still not quite clear. The investigation of the columnar
Information Recording Materials Lab, Lab of Printing & Packaging Material and plastic phase will surely lead to further understanding of the
Technology, Beijing Institute of Graphic Communication, 102600 Beijing, China.
self-assembling process as well as the nature of the photocon-
ductivity. Furthermore, the uidity and high charge mobility of
the columnar plastic phase are also two applicable character-
istics for being charge transport layers in electronic devices.
E-mail: zhangchunxiu@bigc.edu.cn; Fax: +86-10-60261108; Tel: +86-10-60261110
†
Electronic supplementary information (ESI) available: Experimental data,
synthesis, characterization, polarized optical microscopy, and thermal analysis.
See DOI: 10.1039/c3tc31986e
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To date, there are few reports concerning the columnar carbonate and 0.5 equiv. of the appropriate a,u-dibromoalkane
24
plastic phase, even molecules exhibiting this phase are rare. The in reuxing ethanol to give the dimers 4a–k.
aim of this work is to obtain more model discotic molecules
which exhibit a columnar plastic phase and to devise a
systematic study on this phase. Triphenylene derivative hex-
Mesomorphism
The phase behaviors of triphenylene dimers 4a–k were investi-
gated by differential scanning calorimetry (DSC), polarizing
optical microscopy (POM) and variable temperature X-ray
diffraction (XRD). Compounds 4a–c did not show liquid crystal
behavior while compounds 4d–f and 4i–k exhibited two liquid
crystal phases and 4g and 4h gave a single liquid crystal phase.
Phase assignment and transition temperature are summarized
in Fig. 1.
abutyloxytriphenylene (HAT4) which has been frequently
reported to demonstrate a columnar plastic phase is chosen as a
13
precursor to form dimers with the exible linkage O(CH
According to the previous studies on hexapentyloxytriphenylene
HAT5) and hexahexyloxytriphenylene (HAT6), a conclusion can
be drawn that the order of the columnar phase is independent
2 n
) O.
(
20,21
of the exible alkyl linkage chain.
The series of hex-
abutyloxytriphenylene dimers are therefore anticipated to have
a columnar plastic phase.
In the DSC thermograms of compound 4d, two endothermic
ꢁ
ꢁ
peaks located at 94 C and 122 C were observed during the rst
heating run, corresponding to crystalline phase–mesophase and
mesophase–isotropic phase transitions, respectively (Fig. 2).
Even though a signature focal conic texture of the columnar
Results and discussion
Synthesis
ꢁ
phase was observed by POM at 120 C, the DSC curves of the rst
ꢁ
The synthesis of the dimers 4a–k is shown in Scheme 1. Iron(III)
chloride mediated oxidative coupling of 1,2-dibutoxy-benzene
followed by a reductive methanol workup gave 2,3,6,7,10,11-
cooling run exhibited only one exothermic peak at 79 C (Fig. 4b).
22
hexabutyloxytriphenylene.
Selective ether cleavage using
B-bromocatecholborane gave 2-hydroxy-3,6,7,10,11-pentabutoxy-
23
triphenylene, which was reacted with anhydrous potassium
Fig. 1 Graph of phase transition temperatures on heating (above
column) and cooling (below column). Transition temperatures are
ꢁ
ꢀ1
based on the 1st cooling and 2nd heating runs by DSC at 10 C min
Phase assignments of 4a–c are based on the observation of DSC and
POM; 4d–k are based on XRD (Col
¼ hexagonal columnar phase;
Colhp ¼ hexagonal columnar plastic phase; Colrp ¼ rectangular
columnar plastic phase; K , K , and K
¼ crystalline phase).
.
h
Scheme 1 Synthesis of triphenylene dimers 4a–k.
1
2
3
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ꢁ
ꢀ1
.
Fig. 2 DSC curves of 4d with a rate of 10 C min
ꢁ
Fig. 4 (a) Mosaic texture for the Colhp phase of HAT4 at 95 C; (b) focal
ꢁ
conic texture for the Colrp phase of 4d at 90 C; (c) dendritic texture
ꢁ
for the Col
h
phase of 4f at 130 C; (d) mosaic texture for the Colhp
ꢁ
phase of 4f at 110 C; (e) mosaic texture for the Colhp phase of 4g at
50 C; (f) mosaic texture for the Colhp phase of 4h at 150
ꢁ
ꢁ
C
1
(magnification 100ꢂ).
of lower intensity, these peaks were identied as the (200), (110),
020) and (400) reections of a two dimensional rectangular
lattice in which the molecules are tilted with respect to the
(
25,26
column axis.
It was the rst report on a rectangular lattice in
a columnar plastic phase, according to the previous denition
of the rectangular columnar phase, this new phase could be
dened as a rectangular columnar plastic phase. The lattice
˚
˚
constants a and b were calculated to be a ¼ 32.3 A and b ¼ 17.0 A
26
from the spacings of d200 and d110 according to eqn (1).
2
2
2
2
2
1
/dhkl ¼ h /a + k /b
(1)
ꢁ
Fig. 3 (a) XRD pattern of 4d at 120 C on heating and the supposed
ꢁ
structure of the Colrp phase (insert); (b) XRD pattern of 4d at 110 C and
XRD patterns obtained from the cooling process showed
sharp diffraction in the wide-angle regime with no or minimal
peaks in the small-angle regime (Fig. 3b). This type of diffrac-
tion pattern indicated an edge-on alignment with discotic
ꢁ
25
C on cooling and the schematic of the edge-on arrangement
insert), the numbers give the corresponding Bragg distances in A˚ .
(
27
columnar axes oriented parallel to the substrate. On gradually
This transition was identied as a crystalline transition, since the decreasing the temperature, no major changes in the XRD
coexistence of the focal conic texture and small crystalline grains pattern were detected nearby phase transition temperature,
was observed (ESI Fig. 29†). A second order transition which combined with the former POM observations, it was obvious
indicated a crystalline phase–mesophase transition was also that rectangular columnar features were largely preserved.
ꢁ
detected during the second heating run at 84 C.
The DSC curves of 4e, 4f, 4j and 4k all showed two phase
A unique X-ray pattern was observed when heating 4d into its transitions on both heating and cooling runs while 4i only
mesophase from unoriented bulk material (Fig. 3a). At larger observed two phase transitions in the cooling run (Table 1). The
ꢁ
scattering angles (about 2q ¼ 25 ), a doublet reection was high temperature phases of these compounds were identied as
1
6
detected, which is a signature of the columnar plastic phase.
the Colh phase on the basis of the characteristic dendritic
ꢁ
ꢁ
The smaller scattering angles (about 2q ¼ 5 –15 ) showed two texture observed by POM (Fig. 4c). The texture of 4e and 4k did
separate peaks of roughly equal intensity and additional peaks not show any changes when they were cooled to room
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Table 1 Phase behaviours of compounds 4e–k. Transition tempera- Table 2 X-ray diffraction data of compounds 4d and 4f–k obtained
tures and enthalpies were determined by DSC at a scanning rate of 10 from the heating process
ꢁ
ꢀ1
C min
Miller index
d-Spacing/ A˚ (hkl)
Phase (lattice
constants)
ꢁ
ꢀ1
a
ꢁ
Temperature/ C
Phase T/ C (DH/J g ) phase
Process
˚
4
4
4
4
4
4
4
e
Colhp 81.8(ꢀ2.7) Col
Colhp 101(5.1) Col 127.1(16.4) I
Colhp 116.6(ꢀ9.3) Col 130.7(ꢀ16.6) I
Colhp 128(8.9) Col 134.5(14.7) I
Colhp 151.3(ꢀ33.7) I
Colhp 160.8(33.9) I
Colhp 154.2(ꢀ29.3) I
Colhp 161.7(30.1) I
h
123.3(ꢀ15.4) I
1st cooling
2nd heating
1st cooling
2nd heating
1st cooling
2nd heating
1st cooling
2nd heating 4f
1st cooling
2nd heating
1st cooling
4d
120
125
16.17
14.98
8.71
7.94
4.71
3.58
3.49
15.95
9.19
7.96
6.02
4.62
3.61
3.52
17.45
(200)
(110)
(020)
(400)
(211)
(002)
(102)
(100)
(110)
(200)
(210)
(211)
(002)
(102)
(100)
(210)
(220)
(211)
(002)
(102)
(100)
(110)
(210)
(211)
(002)
(102)
(100)
(210)
(211)
(002)
(102)
(100)
(210)
(211)
(002)
(102)
(100)
(210)
(211)
(002)
(102)
(100)
(001)
Colrp (a ¼ 32.3 A)
˚
h
(b ¼ 17.0 A)
f
h
h
g
h
i
Colhp (a ¼ 18.4 A˚ )
h
Colhp 144.8 Col 146.7 I
Colhp 152.1(27) I
j
Colhp 130.6(ꢀ5.7) Col 140.8(ꢀ16.3) I
h
Colhp 137.1 Col
h
143.9 I
2nd heating
1st cooling
2nd heating
k
Colhp 103.3(ꢀ3.2) Col
h
125.8(ꢀ15.6) I
Colhp 110(3.5) Col 129.7(13.1) I
h
4
4
g
120
150
Colhp (a ¼ 20.2 A˚ )
a
Compounds 4e, 4f and 4i–k exhibited two liquid crystal phases.
6
5
4
3
3
.27
.35
.74
.64
.55
temperature although there were obvious transitions on their
DSC curves of the cooling run.
Phase transitions of 4f, 4i, and 4j were clearly observed by
POM, the colours and areas of domain were changed while the
birefringence increased, their textures were nally translated
into mosaic texture (Fig. 4d), and this typical texture was
exactly similar to the texture observed in the hexagonal
columnar plastic phase (Colhp) of HAT4 (Fig. 4a).
When heating powder samples into the liquid crystal phase,
compound 4e did not show any available diffraction in the XRD
pattern. However, the low temperature phase of compounds 4f
and 4i–k gave analogous X-ray diffraction patterns, two
diffraction peaks in the wide-angle regime indicated a columnar
plastic phase, and reections in the small-angle regime were
Colhp (a ¼ 18.8 A˚ )
h
16.30
9.41
6.15
4
3
3
.69
.63
.53
28
Colhp (a ¼ 18.8 A˚ )
4
4
4
i
100
120
80
16.30
6.17
4
3
3
.68
.56
.48
j
16.35
.19
Colhp (a ¼ 18.9 A˚ )
Colhp (a ¼ 19.0 A˚ )
6
4.67
3.56
3.48
26
originated from a hexagonal packing (Table 2). Thus they
could be clearly conrmed as a Colhp phase. Their lattice
constants a were calculated from the spacings of d100 according
to eqn (2). Among these compounds, only 4k showed the
characteristic diffraction peaks of Col
k
16.48
6
4
.41
.71
26
3.56
.48
16.56
.61
3
h
at its high temperature
120
Col
h
(a ¼ 19.12 A˚ )
liquid crystal phase on heating (Fig. 5a).
3
2
2
2
2
1
/dhk ¼ 4(h + k + hk)/3a
(2)
single Colhp phase but neither detailed characterization nor
29
Phase transitions between Col and Col of 4e, 4f, 4j and 4k references were conducted. Textures of 4g and 4h observed by
h
hp
were best observed in the X-ray diffraction patterns obtained on POM were mosaic texture similar to those mentioned above
cooling from the isotropic phase, a single diffraction peak of (Fig. 4e and f). Their DSC traces showed only one peak on both
˚
approximately 3.6 A in the wide-angle in the high temperature heating and cooling, which were identied as phase transitions
phase and the peak split into two reections in the low between the isotropic phase and the mesophase (Table 1). X-ray
temperature phase (Fig. 5b). The XRD pattern of 4i also failed to patterns detected in their mesophases similar to that of 4i
show any characteristic diffraction peaks of the Col
cooling, it may be due to the short temperature range of this
h
phase on indicated a Colhp phase.
A general comparison of phase behaviors between these
phase. An edge-on alignment also obtained when cooling 4e, 4f, dimers and their monomer HAT4 illustrates the signicant role
and 4i–k from their isotropic phases and their XRD patterns played by the exible alkyl linkages in promoting their different
during the cooling process were similar to that of 4d.
packing structures.
Compounds 4g and 4h and compound 4i which was
described above have been reported previously to exhibit a reported previously in a normal columnar phase.
A two-dimensional rectangular lattice has been frequently
26,30,31
It
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26,36
molecules of the neighboring columns.
A strong core–core
interaction would be expected in the columnar phase of 4d for
the short bridge chain between two triphenylene nuclei, which
also introduces a strain in neighboring columns, thus more
likely to meet the requirement for the formation of a rectan-
gular phase. While the exact nature of such an assembly
remains ambiguous, it would nonetheless explain the observa-
tion that column–column separation of 4d is slightly smaller
19
than that of HAT4.
The formation of the Colhp phase in 4e–k can be easily
21,37,38
interpreted on the basis of previous studies of dimers.
The
linkage in dimers was required to be long enough to afford a low
strain bridging between monomeric units. This long spacer
allows sufficient orientational freedom of dimer components
and the structure of the mesophase can be visualized as
columns consisting of stacked separated monomeric units, and
thus the mesophases exhibited by 4e–k are isomorphic with that
of the corresponding monomer HAT4. It is also not complicated
to understand the absence of mesophase in 4a–c, since the
spacers are too short and no motion is possible.
The occurrence of phase transitions between Colhp and Col
h
in 4e, 4f and 4i–k was also of interest, since this type of phase
transition was rarely reported and not emerged in dimers
17,39
before.
There are no signicant differences in rotational
Fig. 5 (a) XRD patterns of 4k at different temperatures on heating
ꢁ
ꢁ
h
at 120 C); (b) XRD patterns of 4e at different
dynamics of the triphenylene molecules between the two phases
(
Colhp at 80 C and Col
temperatures on cooling (Colhp at 60 C and Col
numbers give the corresponding Bragg distances in A˚ .
ꢁ
ꢁ
at 115 C), the as evidenced by B. Gl u¨ sen and coworkers, but the analysis of
XRD and thermal expansion coefficients indicated a higher
intracolumnar ordering in the Colhp phase rather than in the
h
Col
h
phase, hence the charge carrier mobility would be expected
16,17
generally resulted from non-cylindrical columnar cores with to increase in the Colhp phase.
The multiphase behavior of
these dimers would lead to a better understanding of the self-
32
elliptical cross-section orthogonal to the long axis of columns.
Such elliptical cross-sections are generated either by the assembly process and also enable us to study the charge
molecular shape itself, hindered molecular rotation of non- transport mechanisms at various phases in one single system.
3
3–35
disklike molecules around the columnar axis,
or by the tilt
All these compounds 4e–k showed no crystal diffraction peaks
26,32
of the molecular disks with respect to the columnar axis.
The in XRD patterns at room temperature, the results were agreed
short linkage of 4d makes the conformations in which both with the observations from the DSC and POM. A supercooled
triphenylene units are coplanar unlikely. These monomeric columnar plastic phase was conrmed to form at room temper-
units have to tilt with respect to their columnar axis due to the ature. It was mentioned above that the columnar plastic phase
steric crowding when forming the columnar phase via self- was a highly ordered phase with a three-dimensional order, and
assembly (Fig. 6). Columns with tilted cores contribute to the the XRD also showed the shorter stacking distances at the lower
presence of elliptical cross-section which is better suited for a temperature. Thus these materials tend to have greater ordering
rectangular lattice as compared to the hexagonal lattice. It in their supercooled phase, this could be advantageous for room
should also be noted that stronger core–core interactions are temperature electronic applications, since charge carrier mobility
needed for the formation of a rectangular mesophase than that tend to increase with increasing order.
of the hexagonal mesophase, since the molecules of one column
must be tilted in an appropriate way with respect to the
Conclusions
A set of triphenylene-based dimers 4a–k have been synthesized.
Their mesomorphism was fully investigated by DSC, POM and
X-ray diffraction. As we had expected, these compounds for
which n > 4 all formed a highly ordered columnar plastic phase.
In contrast to their monomer HAT4, these dimers exhibited
much richer variety columnar phases. A more orderly rectan-
gular columnar plastic phase was formed by 4d, which is a novel
phase that has not been reported before. Analogous phase
behaviours were observed in 4e, 4f and 4i–k, they formed a
Fig. 6 Schematic illustration of the packing mode of 4d in the Colrp
phase.
hexagonal columnar plastic phase at low temperature as well as
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an ordered hexagonal columnar phase at high temperature. All appropriate a,u-dibromoalkane according to the method
24
these columnar plastic phases except that of 4d could be frozen reported for compound 4g–i.
in a glass state at room temperature. The introduction of a
single interconnecting chain between adjacent molecules did
not signicantly perturb the formation of the columnar plastic
General synthesis of 4a–k
phase. Even though no obvious regularity was found between A mixture of 2-hydroxy-3,6,7,10,11-pentabutyloxytriphenylene 3
the length of linkage and the phase range of these dimers, the (500 mg), a,u-dibromoalkane (0.5 eq.) and anhydrous potassium
appearance of linkages was thought to enrich the mesophases carbonate (1.0 g) in ethanol (20 ml) was heated under reux for 72
ꢁ
of discotic molecules and hinder the crystallization.
h. The mixture was cooled to 0 C, ltered, washed with water (50
Besides the doublet diffraction at larger scattering angles in ml), and extracted with dichloromethane (2 ꢂ 50 ml), the solvent
XRD patterns, mosaic texture was also frequently observed in was removed in vacuo, and the residue was puried by column
the Colhp phase, this type of texture could therefore be deter- chromatography on silica eluting with dichloromethane and
mined as signature texture of this phase. Furthermore, the nally recrystallized from ethanol to give pure 4a–k.
0 0 0 0 0 0
1,2-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-ethane
alignments of these dimers were found to be easily tuned
between face-on and edge-on by heat treatment, it has been 4a (0.25 g, 49%): TLC R : 0.15 (dichloromethane–hexane 2 : 1);
f
proved by XRD patterns which indicated a face-on alignment on (found: C, 75.98; H, 8.87. C78
H
106
O
12 requires: C, 75.82; H,
heating while an edge-on alignment on cooling. This control- 8.65%); IR (KBr): nmax/cm 1260 (C–O–C); d (300 MHz, CDCl
lable alignment is very important for fabrication of electronic 7.81–8.09 (12H, m, ArH), 4.74 (4H, t, OCH CH O), 4.08–4.22
ꢀ
1
H
3
)
2
2
devices such as OLEDs, OPVs and OPCs as well as TFTs.
2 2 2
(20H, m, OCH ), 1.74–1.96 (20H, m, OCH CH ), 1.43–1.69 (20H,
Since only a few molecules were reported to exhibit the phase m, OCH CH CH ), 1.02–1.07 (30H, m, CH ); HRMS (ESI): calc.
2
2
2
3
+
transition between the Col
series of dimers provided more suitable model molecules to
h
phase and the Colhp phase, this m/z 1234.7679 (C H O ), found m/z 1234.7652 (M) .
7
8
106 12
0
0
0
0
0
0
1,3-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-pro-
discuss the relationship between the order of molecular pane 4b (0.32 g, 63%): TLC R : 0.17 (dichloromethane–hexane
f
packing structure and its electronic transportation properties 2 : 1); (found: C, 75.76; H, 8.71. C79
and also facilitate us to investigate the columnar plastic phase 8.71%); IR (KBr): nmax/cm 1261 (C–O–C); d (300 MHz, CDCl )
H
108
O
12 requires: C, 75.93; H,
ꢀ
1
H
3
in a wider temperature range. They were found to have more 7.81–7.96 (12H, s, ArH), 4.58 (4H, t, OCH ), 4.13–4.27 (20H, t,
2
advantages for applications since the charge mobility tends to OCH ), 2.57 (2H, m, OCH CH ), 1.79–1.93 (20H, m, OCH CH ),
2
2
2
2
2
be high in the highly ordered materials. The investigation on 1.47–1.62 (20H, m, OCH CH CH ), 0.89–1.07 (30H, m, CH );
2
2
2
3
photoconductivity of these dimers is proceeding and will be HRMS (ESI): calc. m/z 1248.7835 (C H O ), found m/z
7
9
108 12
+
reported in further work.
1248.7822 (M) .
0
0
0
0
0
0
1
,4-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-butane
c (0.30 g, 59%): TLC R : 0.20 (dichloromethane–hexane 2 : 1);
found: C, 75.90; H, 8.82. C80 12 requires: C, 76.03; H,
(300 MHz, CDCl
), 4.18–4.25 (20H, t, OCH
), 1.82–1.95 (20H, m, OCH CH ), 1.53–
CH CH ), 1.05 (30H, t, CH ); HRMS (ESI):
4
(
f
Experimental
110
H O
ꢀ
1
All solvents employed were purchased from Aldrich and used 8.77%); IR (KBr): nmax/cm 1261 (C–O–C); d
without further purication unless stated otherwise. Column 7.85 (12H, s, ArH), 4.40 (4H, t, OCH
and thin layer chromatography were performed on silica gel 60 2.26 (4H, m, OCH CH
200–300 mesh ASTM) and Silica Gel 60 glass backed sheets, 1.65 (20H, m, OCH
H
3
)
2
),
2
2
2
2
2
(
2
2
2
3
1
+
respectively. H-NMR spectra were recorded in CDCl on Bruker calc. m/z 1262.7992 (C H O ), found m/z 1262.7968 (M) .
3
80 110 12
0
0
0
0
0
0
NMR spectrometers (DMX 300 MHz), chemical shis are given
1,5-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-pentane
in parts per million (d) and are referenced from tetramethylsi- 4d (0.27 g, 51%): TLC R
f
: 0.28 (dichloromethane–hexane 2 : 1);
12 requires: C, 76.14; H,
doublet, t ¼ triplet, and m ¼ multiplet. Fourier transform 8.84%); IR (KBr): nmax/cm 1261 (C–O–C); d (300 MHz, CDCl
infrared spectroscopy (FT-IR) was carried out on a Shimadzu 7.86 (12H, s, ArH), 4.24 (24H, t, OCH ), 2.11 (4H, t, OCH ), 1.89–
FTIR-8400 spectrometer using KBr pellets. The high-resolution 2.08 (22H, m, CH ), 1.53–1.65 (24H, m, OCH CH CH ), 1.05
mass spectrum was recorded on a Bruker Apex IV FTMS mass (30H, t, CH ); HRMS (ESI): calc. m/z 1276.8148 (C81
spectrometer. Elemental analysis (C, H) was performed on an found m/z 1276.8123 (M) .
lane (TMS). Multiplicities of the peaks are given as s ¼ singlet, d (found: C, 76.14; H, 8.85. C81
H
112
O
ꢀ
1
¼
H
3
)
2
2
2
2
2
2
3
112
H O12),
+
0
0
0
0
0
0
Elementar Vario EL CUBE elements analyzer.
Polarising optical microscopy was carried out on a Leica 4e (0.26 g, 49%): TLC R
DM4500P microscope equipped with a Linkam TMS94 hot (found: C, 76.17; H, 8.94. C82
1,6-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-hexane
: 0.30 (dichloromethane–hexane 2 : 1);
12 requires: C, 76.24; H, 8.90%);
stage. Differential scanning calorimetry was carried out on a IR (KBr): nmax/cm 1261 (C–O–C); d (300 MHz, CDCl ) 7.84 (12H,
), 1.92–2.03 (24H, m, OCH CH ), 1.57–
CH ), 1.05 (30H, t, CH ); HRMS (ESI): calc.
f
H O
114
ꢀ1
H
3
ꢁ
ꢀ1
Netzsch DSC 200 at a heating and cooling rate of 10 C min
X-ray diffraction studies were conducted on a Bruker D8 1.73 (24H, m, OCH
Advance diffractometer equipped with a variable temperature m/z 1290.8305 (C82
.
s, ArH), 4.24 (24H, t, OCH
2
2
2
2
CH
2
2
3
+
H
114
0
O
12), found m/z 1290.8314 (M) .
0
0
0
0
0
controller.
1,7-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-heptane
Compounds 1–3 were prepared according to literature 4f (0.31 g, 58%): TLC R : 0.34 (dichloromethane–hexane 2 : 1);
f
1
22,23
procedures and characterized by H-NMR and FT-IR;
(found: C, 76.26; H, 9.02. C83
compounds 4a–f, 4j, and 4k were synthesised from 3 and the IR (KBr): nmax/cm 1261 (C–O–C); d
116
H O
12 requires: C, 76.34; H, 8.95%);
ꢀ
1
H
(300 MHz, CDCl ) 7.84 (12H,
3
1672 | J. Mater. Chem. C, 2014, 2, 1667–1674
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s, ArH), 4.24 (24H, t, OCH
2
), 1.89–1.98 (24H, m, OCH
2
CH
2
), 1.56–
2 R. J. Bushby and O. R. Lozman, Curr. Opin. Solid State Mater.
Sci., 2002, 6, 569–578.
1.68 (26H, m, CH ), 1.05 (30H, t, CH ); HRMS (ESI): calc. m/z
2 3
+
1
304.8461 (C H O ), found m/z 1304.8436 (M) .
3 W. Pisula, M. Zorn, J. Y. Chang, K. M u¨ llen and R. Zentel,
Macromol. Rapid Commun., 2009, 30, 1179–1202.
4 J. Hanna, Opto-Electron. Rev., 2005, 13, 259–267.
5 F. J. M. Hoeben, P. Jonkheijm, E. W. Meijer and
A. P. H. J. Schenning, Chem. Rev., 2005, 105, 1491–1546.
6 Z. An, J. Yu, S. C. Jones, S. Barlow, S. Yoo, B. Domercq,
P. Prins, L. D. A. Siebbeles, B. Kippelen and S. R. Marder,
Adv. Mater., 2005, 17, 2580–2583.
8
3
0
116 12
0
0
0
0
0
1,8-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-octane
4
g (0.22 g, 41%): TLC R
f
: 0.35 (dichloromethane–hexane 2 : 1);
12 requires: C, 76.44; H,
.01%); IR (KBr): nmax/cm 1261 (C–O–C); d (300 MHz, CDCl
.84 (12H, s, ArH), 4.24 (24H, t, OCH ), 1.89–1.96 (24H, m,
CH ), 1.51–1.70 (28H, m, CH ), 1.05 (30H, t, CH ); HRMS
ESI): calc. m/z 1318.8618 (C H O ), found m/z 1318.8598 (M) .
118
(found: C, 76.38; H, 8.95. C84H O
ꢀ
1
9
7
H
3
)
2
OCH
(
2
2
2
3
+
8
4
118 12
0
0
0
0
0
0
1
,9-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-nonane
7 J. Wu, W. Pisula and K. M u¨ llen, Chem. Rev., 2007, 107, 718–
747.
4
h (0.29 g, 52%): TLC R : 0.40 (dichloromethane–hexane 2 : 1);
f
(
9
7
found: C, 76.57; H, 9.0. C85
H
120
O
12 requires: C, 76.54; H,
.07%); IR (KBr): nmax/cm 1260 (C–O–C); d (300 MHz, CDCl
.84 (12H, s, ArH), 4.25 (24H, t, OCH ), 1.83–1.98 (24H, m,
CH ), 1.46–1.68 (30H, m, CH ), 1.05 (30H, t, CH ); HRMS
ESI): calc. m/z 1332.8774 (C85
8 M. O'Neilland and S. M. Kelly, Adv. Mater., 2011, 23, 566–584.
9 D. Adam, F. Closs, T. Frey, D. Funhoff, D. Haarer,
H. Ringsdorf, P. Schuhmacher and K. Siemensmeyer, Phys.
Rev. Lett., 1993, 70, 457–460.
ꢀ
1
H
3
)
2
OCH
(
(
2
2
2
3
H
120
O
12), found m/z 1332.8784 10 D. Adam, P. Schuhmacher, J. Simmerer, L. Haeussling,
+
M) .
K. Siemensmeyer, K. H. Etzbach, H. Ringsdorf and
D. Haarer, Nature, 1994, 371, 141–143.
0
0
0
0
0
0
1,10-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-decane
4
i (0.23 g, 42%): TLC R : 0.45 (dichloromethane–hexane 2 : 1); 11 N. Boden, R. J. Bushby, J. Clements, B. Movaghar,
f
(
9
7
found: C, 76.52; H, 9.09. C86
H
122
O
12 requires: C, 76.63; H,
.12%); IR (KBr): nmax/cm 1263 (C–O–C); d (300 MHz, CDCl
.85 (12H, s, ArH), 4.25 (24H, t, OCH
CH ), 1.26–1.67 (32H, m, CH ), 1.05 (30H, t, CH
ESI): calc. m/z 1346.8931 (C86
K. J. Fonobsn and T. Kreouzis, Phys. Rev. B: Condens.
Matter Mater. Phys., 1995, 52, 13274–13280.
), 1.89–1.98 (24H, m, 12 Z. An, J. Yu, B. Domercq, S. C. Jones, S. Barlow, B. Kippelen
); HRMS and S. R. Marder, J. Mater. Chem., 2009, 19, 6688–6698.
ꢀ1
H
3
)
2
OCH
(
2
2
2
3
+
H
122
O
12), found m/z 1346.8922 (M) . 13 J. Simmerer, B. Gl u¨ sen, W. Paulus, A. Kettner,
0
0
0
0
0
0
1
,11-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-unde-
P.
Schuhmacher,
D.
Adam,
K.
H.
Etzbach,
cane 4j (0.26 g, 47%): TLC R : 0.45 (dichloromethane–hexane
K. Siemensmeyer, J. H. Wendorff, H. Ringsdorf and
D. Haarer, Adv. Mater., 1996, 8, 815–819.
14 A. M. van de Craats, J. M. Warman, A. Fechtenk ¨o tter,
J. D. Brand, M. A. Harbison and K. M u¨ llen, Adv. Mater.,
1999, 11, 1469–1472.
f
2
9
7
: 1); (found: C, 76.55; H, 9.15. C H124O12 requires: C, 76.73; H,
87
ꢀ1
.18%); IR (KBr): nmax/cm 1263 (C–O–C); d
.84 (12H, s, ArH), 4.25 (24H, t, OCH ), 1.89–1.96 (24H, m,
CH ), 1.23–1.67 (34H, m, CH ), 1.05 (30H, t, CH ); HRMS
ESI): calc. m/z 1360.9087 (C87
H
(300 MHz, CDCl
3
)
2
OCH
(
2
2
2
3
+
124
H O
12), found m/z 1360.9038 (M) . 15 A. Ochse, A. Kettner, J. Kopitzke, J. H. Wendorff and
0
0
0
0
0
0
1
,12-Bis(3 ,6 ,7 ,10 ,11 -pentabutyloxytriphenylen-2 -yloxy)-
H. Bassler, Phys. Chem. Chem. Phys., 1999, 1, 1757–1760.
dodecane 4k (0.21 g, 37%): TLC R : 0.48 (dichloromethane– 16 B. Gl u¨ sen, W. Heitz, A. Kettner and J. H. Wendorff, Liq.
f
hexane 2 : 1); (found: C, 76.54; H, 9.10. C H126O12 requires: C,
Cryst., 1996, 20, 627–633.
6.82; H, 9.23%); IR (KBr): nmax/cm 1261 (C–O–C); dH (300 17 B. Gl u¨ sen, A. Kettner and J. H. Wendorff, Mol. Cryst. Liq.
MHz, CDCl ) 7.84 (12H, s, ArH), 4.25 (24H, t, OCH ), 1.89–1.96 Cryst., 1997, 303, 115–120.
), 1.05 (30H, t, 18 P. G. Schouten, J. M. Warman, M. P. de Haas, C. F. van
8
8
ꢀ1
7
3
2
(24H, m, OCH
2
CH
2
), 1.26–1.67 (36H, m, CH
2
CH
3
); HRMS (ESI): calc. m/z 1374.9118 (C88
H
126
O
12), found m/z
Nostrum, G. H. Gelinck, R. J. M. Nolte, M. J. Copyn,
J. W. Zwikker, M. K. Engel, M. Hanack, Y. H. Chang and
W. T. Ford, J. Am. Chem. Soc., 1994, 116, 6880–6894.
9 A. M. van de Craats, J. M. Warman, M. P. de Haas, D. Adam,
J. Simmerer, D. Haarer and P. Schuhmacher, Adv. Mater.,
1996, 8, 823–826.
+
1374.9148 (M) .
1
Acknowledgements
This work is supported by the fund from Beijing Natural Science
Foundation, China (4122027) and Beijing Municipal Education 20 S. Kumar, Liq. Cryst., 2005, 32, 1089–1113.
Commission Project under Grant (no. KM2011 100 15003), the 21 N. Boden, R. J. Bushby, A. N. Cammidge, A. E. Mansoury,
Key (Key grant) Project of Chinese Ministry of Education (no.
11004), Beijing Municipal party committee Organization
P. S. Martin and Z. Lu, J. Mater. Chem., 1999, 9, 1391–
1402.
2
department project under Grant (no. 2010D0 05004000 006) and 22 N. Boden, R. C. Borner, R. J. Bushby, A. N. Carnmidge and
The Importation and Development of High-Caliber Talents
M. V. Jesudason, Liq. Cryst., 1993, 15, 851.
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24 D. Adam, P. Schuhmacher, J. Simmerer, L. H ¨a ussling,
W. Paulus, K. Siemensmeyer, K. H. Etzbach, H. Ringsdorf
and D. Haarer, Adv. Mater., 1995, 7, 276–280.
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