Highly ordered columnar superlattice nanostructures with improved charge carrier mobility by thermotropic self-assembly of triphenylene-based discotics

Article abstract of DOI:10.1039/c9tc04349g

A series of triphenylene esters with two ester groups at 2,3-, 2,7-, 2,6- and 3,6- substituent positions was successfully synthesized and fully investigated. Their self-assembly properties were exhaustively examined by DSC, POM, 1DXRD, 2DXRD, SAXS, TEM methods together with EDM and ESP calculations. It was unexpected that the 3,6-substituted triphenylene ester T5E36 formed an uncommonly helical hexagonal columnar superlattice structure made up of 9₁ right-handed helixes with a pitch of 60.3 ?. This helical superlattice structure was further studied by using transmission electron microscopy and the diameter of the T5E36 particles was found to be at the nanometer scale. Ultimately, the bipolar charge carrier mobility was measured by the time-of-flight method to be in the order of 10^-1 cm² V^-1 s^-1. The formation of this helical superlattice nanostructure no doubt improved their electronic properties and made them more attractive in organic electronics.

Full text of DOI:10.1039/c9tc04349g

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DOI: 10.1039/C9TC04349G
ARTICLE
Highly Ordered Columnar Superlattice Nanostructures with
Improved Charge Carrier Mobility by Thermotropic Self-assembly
of Tripheylene-based Discotics
Received 00th January 20xx,
Accepted 00th January 20xx
Jingze Bia, Hao Wua, Zhenhu Zhanga, Ao Zhanga, Huanzhi Yanga, Yuwen Fenga, Yi Fanga, Lina
DOI: 10.1039/x0xx00000x
Zhanga, Zhengran Wanga, Wentao Qub, Feng Liu*b, Chunxiu Zhang*a
A series of triphenylene esters with two ester groups at 2,3-, 2,7-, 2,6- and 3,6- substituent positions was successfully
synthesized and fully investigated. Their self-assembly properties were exhaustively examined by DSC, POM, 1DXRD,
2DXRD, SAXS, TEM methods together with EDM, ESP calculations. It was unexpected that 3,6-substituted triphenylene
ester T5E36 formed an uncommonly helical hexagonal columnar superlattice structure made up of 91 right-handed helixes
with a pitch of 60.3Å. This helical superlattice structure was further studied by transmission electron microscopy the
diameter of T5E36 particles was found to be at nanometer scale. Ultimately, the bipolar charge carrier mobility was
measured by time-of-flight method at the order up to 10-1 cm2V-1s-1. The formation of this helical superlattice
nanostructure no doubt improved their electronic properties and made them more attractive in organic electronics.
Introduction
To construct highly ordered molecular stacking structures as
well as nanostructures with sophisticated optoelectronic
properties by the assembly of discotic molecules is always an
ultimate goal of researchers in the field of discotic liquid
crystals (DLCs). DLCs are expected to be excellent charge
carrier transport materials in optoelectronics devices such as
field effect transistors, photovoltaic solar cells and light
emitting diodes 1-6. Recent studies on ester groups substituted
triphenylene DLCs have demonstrated that the dipole-dipole
interactions of polar groups have a special guidance on the
order and scale of self-assembled mesophase structures.
The first triphenylene based DLCs, hexa-n-alkanotes
triphenylenes, which were symmetrical hexasubstituted
triphenylene esters were recognized by Billard, Dubois and
Destrade in 1979 after the discovery that disc-shaped
molecules benzene-hexa-n-alkanoates could form liquid
crystals of Chandrasekhar in 1977 7-9. Early studies of
triphenylene esters mainly focused on the new symmetrical
hexasubstituted and asymmetrical mono-, di- and tri-
substituted compounds. Interestingly, they exhibited the
characteristic hexagonal columnar (Colh) phases that were
Fig. 1 a) Molecular formula of T5E36; b) Optimized conformation and
dipole moment of T5E36; c) Helical column of T5E36.
found to be monotropic mesophases 10-12. Compared with
triphenylene ethers which were the counterparts of another
big part of DLCs, mesogenic triphenylene ester derivatives
showed decreases in the melting point and substantial
broadenings in the liquid crystal phases. That was, the Colh
phase can be maintained even at room temperature and this
13-15
ordered structure can be suppressed in glassy states
.
Spiess and coworkers reported an unsymmetrical chiral ester
groups substituted pentakis(pentyloxy)triphenylene and
proposed that the steric effects strongly stabilized the
intramolecular interactions due to the preferred out-of-plane
conformations and the dipole moments of ester substituents.
These intramolecular interactions significantly increased the
clearing temperatures and suppressed the crystallizations
giving rise to substantially lower glass transition temperatures
a. Information Recording Materials Lab, Beijing Key Laboratory of Printing &
Packaging Materials and Technology, Beijing Institute of Graphic Communication,
Beijing, 102600 (P. R. China), E-mail: zhangchunxiu@bigc.edu.cn
b. State Key Laboratory for Mechanical Behaviour of Materials, Shaanxi
International Research Center for Soft Matter, Xi’an Jiaotong University, Xi’an
710049 (P. R. China), E-mail: feng.liu@xjtu.edu.cn
Electronic
Supplementary
Information
(ESI)
available:
See
DOI: 10.1039/x0xx00000x
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16. Their another work reported a superstructure existed in the elements analyzer. The thermal properties of discotic liquid
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chiral ester group substituted pentakis(pentyloxy)triphenylene crystals were characterized by usingDdOiIf:f1e0r.1e0n3t9ia/Cl9TsCca04n3n4i9nGg
for the occurrence of an additional peak at small angle region. calorimeter (DSC) on a Netzsch DSC 200. Its optical properties
However, the insight of this superstructure could not be fully were characterized by a Polarizing Microscope (POM) on a
elucidated at that time 17. Simultaneously, Wendorff and Leica DM4500P with a Linkam TMS94 hot stage. The structural
coworkers synthesized another type of mono-substituted characterizations of samples were characterized by 1D X-ray
triphenylene
carboxylic
esters
based
on diffraction (1DXRD) through
a
a
Bruker D8 Advance
variable temperature
hexapentyloxytriphenylenes (HAT5). The reflection near 2θ = diffractometer equipped with
2.5° in the small angle region of XRD pattern was the first controller; two-dimensional X-ray diffraction (2DXRD) using a
evidence for the formation of a novel discotic mesophases 40KV FL tube as the X-ray source (Cu Ka) and the small-angle X-
superstructure caused by bulky substituents and polar ray scattering (SAXS) (SAXSess, Anton Paar) equipped with
substituents 18.Takuzo Aida and coworkers restudied the Kratky block-collimation system. The structure and
mesophases of triphenylene hexacarboxylic esters and morphology were investigated by Transmission Electron
confirmed that even a small aromatic mesogen such as Microscope (FEI Tecnai G2 20 STWIN).
triphenylene esters enabled an exceptionally wide-range 2D Syntheses
lattice correlation owing to the intercolumnar dipole–dipole
As the workhorse of discotic liquid crystals, triphenylenes have
interaction which lead to a large-area homeotropic columnar
been frequently studied since they are relatively easy to be
orientation. A rather high hole mobility was obtained along
synthesized and processed. The syntheses of intermediates
with its anisotropic nature up to 5x10-3 cm2V-1s-1 19. Takanori
functional di-hydroxyl substituted triphenylenes were based
Fukushima
and
coworkers
constructed
a
novel
on
previous
works.
For
2,3-di-hydroxyl-6,7,10,11-
dibenzo[a,c]phenazine disc-molecule with
a large dipole
tetrapentyloxytriphenylene, the synthetic route by using
lithium diphenylphosphine as a catalyst to make cleavage of
moment. The synchrotron radiation XRD results confirmed the
formation of a 2D superlattice structure via the hierarchical
columnar assemblies of discotic liquid crystals 20. Our recent
works based on triphenylene esters also exhibited the
supperlattice nanostructures with high charge carrier mobility
21-23. Nevertheless, how the substituted positions decisively
influenced the properties of the molecules not only in
complanate two dimensional lattice correlations but also in
three dimensional lattice structures was still unsolved.
two methyloxyl groups reported by Bushby in the year of 1995
24
.
The 2,7-di-hydroxyl-3,6,10,11-tetrapentyloxytriphenylene
was hard to be synthesized, but we are still enable to employ
the general regiospecific synthesis reported by Boden in 1995
which was very similar to the synthesis of 2,3-di-hydroxyl-
6,7,10,11-tetrapentyloxytriphenylene 25. For 2,6-di-hydroxyl-
3,7,10,11-tetrapentyloxytriphenylene, we used a synthetic
procedure for the preparation of di- and tri- functional
triphenylene derivatives starting from the readily available
hexakis(pentyloxy)triphenylene by selective ether cleavages
with B-bromocate-cholborane reported by Kumar in 1997,
which mainly obtained 2,6-, 2,6,10- and 2,7,11- hydroxyl
substituted triphenylene derivatives 13. For 3,6-di-hydroxyl-
Experimental section
Materials
All chemicals were purchased from Aladdin, and all solvents
from Aldrich. All chemicals and solvents were used without
further purification. Silica gel 60 (200-300 mesh ASTM) and
silica gel 60 glass thin-layer chromatography were used for the
purification and identification of the reactions, respectively.
Instrumentations
2,7,10,11-tetrapentyloxytriphenylene, we took
a click-on
method reported by our group in 2014 with very high yield up
to 24.7% 26. The detailed syntheses of T5E23, T5E27, T5E26
and T5E36 are provided in ESI.
The 1H-NMR spectra were recorded by a Bruker NMR
spectrometer (DMX 300 MHz) in CDCl3, Chemical shifts are
given as units of measurement and expressed in parts per
million (δ) with tetra-methylsilane (TMS) as a reference.
Multiplicities of peaks are expressed as s = singlet, d = doublet,
t = triplet, m = multiplet; The KBr pellets were used to make
the test samples and the infrared spectrum (FT-IR) was
recorded on a Shimadzu FTIR-8400 spectrometer by Fourier
transform; The high resolution mass spectrum was recorded
on a Bruker Apex IV FTMS mass spectrometer. Elemental
analysis (C, H) was performed on an Elementar Vario EL CUBE
Results and discussion
Herein, we successfully synthesized triphenylene esters
T5E23, T5E27, T5E26 and T5E36 with two ester groups at
different substituent positions where T, 5 and E refer to
triphenylene, pentyloxy and ethoxycarbonyl, respectively,
while 23, 27, 26 and 36 refer to the substituent positions of
ethoxycarbonyl. Their mesophases and self-assembly
properties have been systematically studied and shown in
Fig.2.
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Considering the results of the polarizing optical temperature broke the liquidity, continuity and peculiar
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DOI: 10.1039/C9TC04349G
microscopy (POM), differential scanning calorimetry (DSC) and physical property of liquid crystals, which were not conducive
to their applications.T5E26 and T5E36 showed pseudo focal
conic textures that have been proved to be typical hexagonal
columnar textures at 160°C and 165°C during the cooling,
respectively, which can be maintained at the room
27
temperature without any changes in liquid crystal textures
.
The DSC results of T5E26 showed only an exothermic peak at
168.1°C during heating and an endothermic peak at 164.2°C
during cooling. Nevertheless, T5E36 showed two exothermic
peaks at 134.9°C and 173.1°C during heating as well as two
endothermic peaks at 121.1°C and 167.4°C during cooling.
Combining with the 1DXRD data of T5E36 obtained at 30°C,
100°C and 150°C during second heating (Fig. 2d), the
diffraction peaks in the range of 2θ = 520° can be indexed to
(100), (110), (200) and (210) with the reciprocal d-spacing
ratios 1,1/√3,1/2,1/√7 which were attributed to hexagonal
packing 28. When the temperature dropped to 30°C, under the
second phase transition temperature of T5E36, the sharp
diffraction peak in the wide angle region (about 2θ = 26°) split
into two peaks, which was the evidence of a more ordered
hexagonal columnar phase.
The 1DXRD patterns, lacked of lattice dimensionality of
the liquid crystalline structure, were not adequate to analysis
more detailed structures. So we collected two-dimensional X-
ray diffraction (2DXRD) and small-angle X-ray scattering (SAXS)
patterns of T5E26 and T5E36 (Fig. 3a, b). After careful
purification of the samples, we put the purified samples into a
cuboid container made of aluminum foil, ensuring the
thickness was about 10 μm. Whereafter, the samples were
Fig. 2 a) Molecular formulas of T5E23, T5E27, T5E26 and T5E36 (from
left to right); b) POM images of T5E23 at 135°C, T5E27 at 155°C, T5E26
at 160°C and T5E36 at 165°C (from left to right) with scale bar = 50μm; c)
Graph of phase transition temperatures on heating (left column) and
cooling (right column) based on the 1st cooling process and 2nd heating
process by DSC(Iso=isotropic phase, Colh=hexagonal columnar phase and
K = crystalline phase); d) 1DXRD patterns of T5E36 at 30°C, 100°C and
150°C.
one-dimensional X-ray diffraction (1DXRD) (Fig. 2, S9, S10)
T5E23 and T5E27 showed hexagonal columnar phases during
the cooling. But ultimately their crystallizations at room
,
Fig. 3. 2DXRD patterns of oriented samples at room temperature: a) T5E26; b) T5E36; c) SAXS diffractograms of T5E26 (up) and T5E36 (down) recorded at
room temperature; d) Optimized conformation and schematic diagram of T5E36 (pink arrow: the direction of dipole moment); e) Self-assembly of three T5E36
molecules; f) Model of hexagonal lattice and hexagonal superlattice.
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placed on a heating stage and annealed from the temperature region (2θ = 19°±1°, d = 4.6±0.1Å) marked with purple circles
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just below clearing point to room temperature over a whole (Fig. 3a, b). In order to get the insight ofDthOeI: s10tr.1u0c3t9u/rCe9ToCf0T453E493G6,
night at a rate of 0.5°C/min. Eventually, good samples with
monodomains for 2D WAXD measurement were obtained.
Both T5E26 and T5E36 presented ordered diffraction spots in
the low angle region that can be designated as (100), (110)
(200) and (210), respectively, indicating that incident beam
was perpendicular to the molecular plane 29. Nevertheless,
there were also six distinct diffraction spots corresponding to
another 100 plane appeared in the inner region with the d-
spacings equaled to 32.7Å and 32.6Å of T5E26 and T5E36,
respectively. In combination with the results of SAXS patterns
(Fig. 3c), it was confirmed that the d-spacings of the inner
region was almost twice as the d-spacings of (100) in
hexagonal lattice which was 16.4Å and 16.3Å for T5E26 and
Fig. 4. a) Linearly adjusted 2DXRD pattern of T5E36; b) Reciprocal lattice
of T5E36 (green arrows and blue lines: hexagonal lattice, red arrows and
T5E36, respectively. According to our previous works on 2D
orange line: hexagonal superlattice).
superlattice nanostructures, it was confirmed that T5E26 and
T5E36 formed 2D superlattice under the guidance of long-
range dipole-dipole interactions. The a parameters were
calculated to be acolh1 = 18.9Å, acolh2 =37.8Å for T5E26 and acolh1
= 18.8Å, acolh2 = 37.6Å for T5E36 in hexagonal lattice and
hexagonal supperlattice respectively 30. For T5E36, each
molecule only possessed a large dipole moment in plane from
center of two ester groups to opposite alkyl chains showed as
subsequently, we linearly adjusted the intensity (Fig. 4a) and
reconstructed the reciprocal lattice space (Fig. 4b) of T5E36
pattern. Superficially, these diffraction spots always came in
pairs and some of these diffractions did not belong to both of
the two hexagonal lattices exhibiting a higher intensity. The
powder 2DXRD pattern of T5E36 (Fig. S12) also performed an
obvious diffraction halo when d-spaceing was near 4.6Å, which
was stronger than other diffractions except for (100) and π-π
pink arrow (Fig. 3d) which must be cancelled out in order to
stackings. These results evidenced the ordered arrangement of
get the steadiest and the most compact stacking. With flexible
the peripheral ester groups and further implied the existence
alkyl chains located in the center, three molecules assembled
of a more ordered hexagonal phase.
into a triangular shaped building block from three directions to
In order to expound further on the phase structure of
minimize the net dipole and the contact area of side chains
T5E36, we prepared the oriented sample by mechanical
(Fig. 3e). This triangular shaped building block was essential
shearing with a mild external force at 120°C just below the
for the formation of hexagonal closest packing and arranged
isotropic temperature, followed by fast cooling to room
latterally to form an extented hexagonal lattice (Fig. 3f)
.
temperature. After that, sheared T5E36 sample was placed
vertically on the sample stage to make sure that the incident
Different from T5E26, 2DXRD pattern of T5E36 showed a
series of sharp diffractions of high intensity in wide angle
Fig. 5. a) 2DXRD patterns of sheared T5E36 at room temperature with shear direction and layer lines labelled; b) Schematic diagram of 2DXRD measurement
of sheared T5E36 sample; c) Enlargement in low angle region with meridian and equator labelled.
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X-ray beam can be perpendicular to shear direction (Fig. 5b)
ARTICLE
.
density map (EDM) reconstructed from 1DXRD data at 30°C
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Fig. 5a showed the 2DXRD pattern of sheared sample which and the electrostatic potential (ESP) isoDsuOrIf:a1c0e.10c3a9l/cCu9lTaCti0o4n3s49aGt
was recorded at room temperature. The (hk0) diffractions of the B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) level with Gaussian
the hexagonal phase at low angle region on the equator (Fig. 09 package (Revision C.01) were performed (Fig. 6) 35-37. Each
5c) can be designated as (100), (110), (200) and (210) red area with the highest electron density represented
indicating that the axes of columns were well aligned along the positions of the aromatic core of the triphenylene, while the
shear direction (the meridian). The numerous sharp meridional surrounding yellow, green and blue areas were packed with
and off-meridional diffractions demonstrated
a periodic ester groups and alkyl tails. As the a parameter of hexagonal
organization of molecules along the columns with long range lattice labeled in Fig. 6a, the white arrow line that was the
intra- and intercolumnar order. Furthermore, the cross-like diameter of columns equaled to the distance between
pattern of diffractions and 18 overt layer lines can be inferred adjacent columns and also equaled to the a parameter of the
to a helical arrangement in the columns 31-33. The first hexagonal lattice. Therefore, the diameter of each column in
diffractions on the meridian (i and h) which was corresponded this hexagonal lattice Dcolumn equaled to 18.8Å. In Fig. 6b, the
to the subunit axial translations H appearing at 6.7Å was 3,6 position ester groups of T5E36 out of the triphenylene
attributed to layer line L = 9. Thus, a helical pitch and repeat plane in contradictory directions possessed a high value of
containing 9 subunits can be well defined. This kind of self- electrostatic potential. This electrostatic potential gave the
assembly structure was classified as a 91 helix with a pitch of P opportunity to an ordered arrangement of the peripheral ester
= 6.7Å×9 = 60.3Å which was also corresponded to reciprocal groups which were already observed from 2DXRD pattern of
distance between equator and layer line L = 1 34,35. In the T5E36.
meantime, the strong diffractions emerged on the meridian at
With the help of all the results above, we reconstructed
3.4Å (k and j) which was attributed to layer line L = 18 in the the model of molecules and supramolecular columns (Fig. 7)
.
wide angle region represented a compact π-π stacking As so many alkyl chains were not good for clarity, we only used
between adjacent molecules. So the lattice parameters for polyhedrons and circular cones to represent triphenylene
cores and ester groups respectively. The subunit axial
translations H = 6.7Å which was twice the distance of adjacent
molecules indicated that two T5E36 molecules rotated
together with the azimuthal rotation angle φ = 360/9 = 40°.
This angle also led to
a constant distance between
intramolecular ester groups out of plane in contradictory
direction, which was about 4.6Å and can be easily observed in
the 2DXRD pattern because of the intense electronic
interaction of ester groups. As the T5E36 only had a C2
symmetry axis in plane, two different rotations of the
molecules can lead to right-handed and left-handed helixes.
However, the distance between adjacent ester groups of left-
handed helix was much larger than 4.6Å which will also reduce
the molecules stability decisively. In order to accomplish a
more stable and compact conformation, T5E36 tended to form
right-handed helical columns. These columns also possessed a
large c parameter of 60.3Å which was formed due to the
triphenylene core and ester groups seeking the opportunity of
close packing simultaneously. The most possible manner was
Fig. 6. a) Reconstructed electron density map of T5E36 with scale bar
from high density (red) to low density (blue); b) Electrostatic potential
isosurface calculations of T5E36 with scale bar from negative electrostatic
potential (red) to positive electrostatic potential (light blue).
T5E36 were calculated to be a = b = 18.8Å, c = 60.3Å and γ =
120°.
To investigate the model of T5E36 deeply, the electron
Fig. 7. Possible models of T5E36 with green ticks refer to right arrangement and red crosses refer to wrong arrangement: a) Model of triphenylene core; b)
Result of two different rotations; c) Right-handed helix (left) and left-handed helix (right); d) Model of supramolecular columns.
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just a slight rotation of molecules with respect to others in the sample and generated charge carriers. The results of
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column and helically assembled along the column axis, forming photocurrent were analyzed in double logarithmic plots
a 9-fold helix.
recorded by a digital oscilloscope. The transient photocurrents
This long-range superlattice nanostructure can be easily for hole and electron of T5E36 at room temperature and
perceived in transmission electron microscopy (TEM) which mobility changes depending on temperatures were presented
was considered to be an essential way to characterize the in Fig. 9. The non-dispersive curve with a plateau region
morphology of self-assembly structures. Fig. 8 showed the followed by a sigmoidal decay indicated that the charge
TEM (FEI Tecnai G2 20 STWIN) image of T5E36. We took a transport was Gaussian-type and can be described as a band-
particle count by using Nano Measure software to find out like transport model. The transit time t can be determined by
almost mono-dispersed T5E36 particles with diameters near the inflection point in the transient photocurrent curves and
the charge carrier mobility can be calculated according to
eqation below, where V and d were the applied voltage and
sample thickness which was 9 μm here, respectively.
μ=d2/Vt
The hole and electron mobility can reach high up to 1.8×10-1
cm2V-1s-1 and 2.0×10-1 cm2V-1s-1 which were much higher than
previously reported works while the mobility of most
triphenylene derivatives without forming helical superlattice
nanostructure was 10-2 10-3 cm2V-1s-1 42,43. As temperature

raised higher than 120°C, the mobility of T5E36 exhibited a
sudden decline which was entirely accorded with the transtion
from helical hexagonal phase to hexagonal phase on heating.
Thus,we can draw a conclusion that the formation of helical
superlattice nanostructure notably improved bipolar charge
carrier mobility.
Fig. 8 a) TEM image with scale bar= 100 nm and particle count result of
TEM image b) TEM image with scale bar= 20 nm
11.5 nm 38,39. With the help of Scherrer equation 40
,
D=Kγ/(Bcosθ)
where K is the Scherrer constant
，γ is the X-ray wavelength, B
is the peak width of the diffraction peak at half maximum
height and θ is the diffraction angle. The correlation length D
of column-column was calculated to be 11.3 nm from 1DXRD
results which was fine consistent with the diameter of T5E36
particles in TEM images.
Conclusions
In summary, we have successfully synthesized a series of
triphenylene esters with ester groups at different substituent
positions. After ample analyzation of the POM, DSC, 1DXRD,
2DXRD, EDM and ESP results, we demonstrate that only T5E36
with two ester groups out of plane in the contrary direction
self-assembles to form a 91 right-handed helical ordered
The intrinsic charge carrier mobility of T5E36 was
superlattice structure.The TEM images testify
a mono-
dispersion of T5E36 particles with diameter near 11.5 nm
which approximately equal to the correlation length of
column-column.Finally, intrinsic charge carrier mobility of
T5E36 measured by TOF method manifests unprecedented
high hole and electron mobility up to 10-1 cm2V-1s-1 during its
helical phase.These results are expected to play an important
role in elucidations of fundamental aspects of self-assembly
and applications on optoelectronic devices based on ester-
modified triphenylene derivatives.
Conflicts of interest
There are no conflicts to declare
Fig. 9 Double logarithmic plots of typical transient current I as a function of
time t of T5E36 in an electric field of E = 2.2 ×104 Vcm-1 at 20 °C: a) hole
mobility of T5E36: μh = 1.76×10-1 cm2V-1s-1; b) electron mobility of T5E36:
μe = 1.77 ×10-1 cm2V-1s-1; Mobility of T5E36 as a function of temperature
from 20°C to 160 °C c) hole d) electron.
Acknowledgements
measured by time-of-flight (TOF) method from room
temperature to 160°C 41. At the isotropic temperature, the
fully purified T5E36 was filled by capillary action into a liquid
crystal cell consisted of two ITO glass substrates. A nitrogen
This work is supported by State Key Laboratory for Mechanical
Behavior of Materials (20171913), the Natural Science
Foundation of China (No. 51702019), the Beijing Natural
Science Foundation of China (2172024), the Beijing Municipal
Education Commission Project under Grant (No.
pulse laser (
λ=337nm, Pulse duration = 600 ps) irradiated the
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ARTICLE
27 M. T. Allen, K. D. M. Harris, B. M. Kariuki, N. VKieuwmAratircile, OJ.nliAne.
Preece, S. Diele, D. Lose, T. HegmaDnOnI: a10n.d103C9./CT9sTcCh0ie4r3s4k9eG,
Liquid Crystals, 2000, 27, 689-692.
28 S. K. Prasad, D. S. S. Rao, S. Chandrasekhar and S. Kumar,
Molecular Crystals and Liquid Crystals, 2003, 396, 121-139.
29 Z. Chen, U. Baumeister, C. Tschierske and F. Würthner,
Chemistry – A European Journal, 2007, 13, 450-465.
KM201210015008), the Beijing Municipal Commission of
Education Foundation for Ability Construction of Scientific and
Technological Innovation Service (Research on Nanoscale
Copper Conductive Ink, PXM2017_014223_000036).
30 S. Laschat, A. Baro, N. Steinke, F. Giesselmann, C. Hägele, G.
Scalia, R. Judele, E. Kapatsina, S. Sauer, A. Schreivogel and M.
Notes and references
1
P. G. Schouten, J. M. Warman, M. P. de Haas, C. F. van
Nostrum, G. H. Gelinck, R. J. M. Nolte, M. J. Copyn, J. W.
Zwikker and M. K. Engel, Journal of the American Chemical
Society, 1994, 116, 6880-6894.
Tosoni, Angewandte Chemie International Edition, 2007, 46
,
4832-4887.
31 C. Roche, H.-J. Sun, M. E. Prendergast, P. Leowanawat, B. E.
Partridge, P. A. Heiney, F. Araoka, R. Graf, H. W. Spiess, X.
Zeng, G. Ungar and V. Percec, Journal of the American
Chemical Society, 2014, 136, 7169-7185.
2
3
S. Sergeyev, W. Pisula and Y. H. Geerts, Chemical Society
Reviews, 2007, 36, 1902-1929.
L. Schmidt-Mende, A. Fechtenkötter, K. Müllen, E. Moons, R.
H. Friend and J. D. MacKenzie, Science, 2001, 293, 1119.
B. R. Kaafarani, Chemistry of Materials, 2011, 23, 378-396.
A. M. van de Craats, N. Stutzmann, O. Bunk, M. M. Nielsen,
M. Watson, K. Müllen, H. D. Chanzy, H. Sirringhaus and R. H.
Friend, Advanced Materials, 2003, 15, 495-499.
32 C. Roche, H.-J. Sun, P. Leowanawat, F. Araoka, B. E. Partridge,
M. Peterca, D. A. Wilson, M. E. Prendergast, P. A. Heiney, R.
Graf, H. W. Spiess, X. Zeng, G. Ungar and V. Percec, Nature
4
5
Chemistry, 2015, 8, 80.
33 M. Peterca, V. Percec, M. R. Imam, P. Leowanawat, K.
Morimitsu and P. A. Heiney, Journal of the American
Chemical Society, 2008, 130, 14840-14852.
6
7
8
9
H. Fujikake, T. Murashige, M. Sugibayashi and K. Ohta,
Applied Physics Letters, 2004, 85, 3474-3476.
C. Destrade, M. C. Mondon and J. Malthete, J. Phys.
Colloques, 1979, 40, C3-17-C13-21.
A. BÉGuin, J. Billard, J. C. Dubois, N. H. Tinh and A. Zann, J.
Phys. Colloques, 1979, 40, C3-15-C13-16.
34 C. Knupp and J. M. Squire, Journal of Applied
Crystallography, 2004, 37, 832-835.
35 S.-X. Fa, X.-F. Chen, S. Yang, D.-X. Wang, L. Zhao, E.-Q. Chen
and M.-X. Wang, Chemical Communications, 2015, 51, 5112-
5115.
S. Chandrasekhar, B. K. Sadashiva and K. A. Suresh, Pramana,
1977, 9, 471-480.
36 V. Percec, H.-J. Sun, P. Leowanawat, M. Peterca, R. Graf, H.
W. Spiess, X. Zeng, G. Ungar and P. A. Heiney, Journal of the
American Chemical Society, 2013, 135, 4129-4148.
37 M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A.
Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci,
G. A. Petersson, Gaussian 09, Revision C.01; Gaussian, Inc.,
Wallingford, CT, 2011.
10 J. Billard and B. K. Sadashiva, Pramana, 1979, 13, 309-318.
11 C. Destrade, N. H. Tinh, H. Gasparoux, J. Malthete and A. M.
Levelut, Molecular Crystals and Liquid Crystals, 1981, 71
111-135.
,
12 A. M. Levelut, F. Hardouin, H. Gasparoux, C. Destrade and T.
Nguyen Huu, J. Phys. France, 1981, 42, 147-152.
13 M. Manickam and S. Kumar, Molecular Crystals and Liquid
Crystals, 1999, 326, 165-176.
38 X.-Q. Wei, G. F. Payne, X.-W. Shi and Y. Du, Soft Matter,
2013, 9, 2131-2135.
39 L. Zeng, Q.-H. Guo, Y. Feng, J.-F. Xu, Y. Wei, Z. Li, M.-X. Wang
and X. Zhang, Langmuir, 2017, 33, 5829-5834.
14 S. Kumar, Liquid Crystals, 2004, 31, 1037-1059.
15 I. G. Voigt-martin, R. W. Garbella and M. Schumacher, Liquid
Crystals, 1994, 17, 775-801.
40 A. Monshi, M. R. Foroughi and M. Reza Monshi, World
Journal of Nano Science and Engineering, 2012, 2, 154-160.
16 S. U. Vallerien, M. Werth, F. Kremer and H. W. Spiess, Liquid
41 V. Podzorov, E. Menard, A. Borissov, V. Kiryukhin, J. A.
Rogers and M. E. Gershenson, Physical Review Letters, 2004,
93, 086602.
Crystals, 1990, 8, 889-893.
17 M. Werth, S. U. Vallerien and H. W. Spiess, Liquid Crystals,
1991, 10, 759-770.
42 M. Kumar and S. Kumar, Polymer Journal, 2016, 49, 85
43 T. Wöhrle, I. Wurzbach, J. Kirres, A. Kostidou, N. Kapernaum,
J. Litterscheidt, J. C. Haenle, P. Staffeld, A. Baro, F.
18 A. Kettner and J. H. Wendorff, Liquid Crystals, 1999, 26, 483-
487.
19 T. Osawa, T. Kajitani, D. Hashizume, H. Ohsumi, S. Sasaki, M.
Takata, Y. Koizumi, A. Saeki, S. Seki, T. Fukushima and T.
Giesselmann and S. Laschat, Chemical Reviews, 2016, 116
1139-1241.
,
Aida, Angewandte Chemie International Edition, 2012, 51
7990-7993.
,
20 M.-C. Yeh, Y.-L. Su, M.-C. Tzeng, C. W. Ong, T. Kajitani, H.
Enozawa, M. Takata, Y. Koizumi, A. Saeki, S. Seki and T.
Fukushima, Angewandte Chemie International Edition, 2013,
52, 1031-1034.
21 W. Zhang, S. Zhang, Z. Zhang, H. Yang, A. Zhang, X. Hao, J.
Wang, C. Zhang and J. Pu, The Journal of Physical Chemistry
B, 2017, 121, 7519-7525.
22 Z. Zhang, H. Yang, J. Bi, A. Zhang, Y. Fang, Y. Feng, L. An, L.
Liang, C. Zhang and J. Pu, New Journal of Chemistry, 2018,
42, 20087-20094.
23 Z. Zhang, H. Yang, A. Zhang, J. Bi, Y. Feng, W. Zhang, C. Zhang
and J. Pu, Journal of Materials Chemistry C, 2018, 6, 5597-
5600.
24 N. Boden, R. J. Bushby, A. N. Cammidge and P. S. Martin,
Journal of Materials Chemistry, 1995, 5, 1857-1860.
25 N. Boden, R. J. Bushby and A. N. Cammidge, Journal of the
American Chemical Society, 1995, 117, 924-927
26 H. Wu, C. Zhang, J. Pu and Y. Wang, Liquid Crystals, 2014, 41
,
1173-1178.
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DOI: 10.1039/C9TC04349G