Novel columnar liquid crystalline oligomers: Triphenylene tetramers with rigid aromatic Schiff-bases and hydrogen-bonding spacers via click chemistry

Article abstract of DOI:10.1016/j.molliq.2017.04.007

Three novel triphenylene tetramers with triazole bridges, rigid aromatic Schiff-bases and hydrogen-bonding spacers were designed and synthesized in yield of 73–78%. Their structures were confirmed by IR, NMR and MS. Their mesomorphic properties were studi

Full text of DOI:10.1016/j.molliq.2017.04.007

Accepted Manuscript
Novel columnar liquid crystalline oligomers: Triphenylene
tetramers with rigid aromatic Schiff-bases and hydrogen-bonding
spacers via click chemistry
Shengjie Jiang, Hongyu Guo, Shuyun Zhu, Fafu Yang
PII:
S0167-7322(17)30462-2
doi: 10.1016/j.molliq.2017.04.007
MOLLIQ 7157
DOI:
Reference:
To appear in:
Journal of Molecular Liquids
Received date:
Revised date:
Accepted date:
2 February 2017
10 March 2017
3 April 2017
Please cite this article as: Shengjie Jiang, Hongyu Guo, Shuyun Zhu, Fafu Yang , Novel
columnar liquid crystalline oligomers: Triphenylene tetramers with rigid aromatic Schiff-
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ACCEPTED MANUSCRIPT
Novel columnar liquid crystalline oligomers: Triphenylene tetramers with
rigid aromatic Schiff-bases and hydrogen-bonding spacers via click
chemistry
1
1*
1
1,2, 3*
Shengjie Jiang , Hongyu Guo , Shuyun Zhu , and Fafu Yang
1
College of Chemistry and Chemical Engineering, Fujian Normal University, Fuzhou 350007, P. R. China
Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, P. R. China
2
3
Fujian provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, Fuzhou 350007, China
Corresponding author; e-mail: yangfafu@fjnu.edu.cn; Tel.: +0086-591-83465225; fax: +0086-591-83465225;
*
Abstract Three novel triphenylene tetramers with
triazole bridges, rigid aromatic Schiff-bases and
hydrogen-bonding spacers were designed and
synthesized in yield of 73~78%. Their structures were
confirmed by IR, NMR and MS. Their mesomorphic
properties were studied by polarizing optical
microscopy, differential scanning calorimetry and X-ray
diffraction. These novel triphenylene tetramers
possessed the hexagonal columnar mesophase and
exhibited excellent mesomorphic properties with
For the purpose of transferring liquid crystalline
monomer to macromolecular material, much attention
has been paid to liquid crystal oligomers. The liquid
crystalline oligomers were good model molecules for
polymeric materials due to the similarities in their
transitional behaviors. Moreover, they had the
advantage of simple purification and characterization,
and some of them exhibited special fluid phases with
interesting functions. Up to now, many triphenylene
liquid crystalline dimers with various soft or rigid
spacers, and some triphenylene liquid crystalline
trimers were designed and synthesized [22-36]. Their
mesomorphic properties were greatly influenced by the
structures of both triphenylene units and spacers.
However, as to triphenylene tetramer which might be
more similar to polymeric material, only a few
examples were presented. Kumar reported the
o
melting points at 30~60 C, which was first observed
near room temperature for triphenylene tetramers. This
study suggested that the mesomorphic properties of
triphenylene oligomers could be tuned conveniently by
the structures of spacers.
Keywords
21
Triphenylene ·Tetramer ·Synthesis ·Mesophase ·Room
temperature
triphenylene tetramers bridged by rufigallol.
Markovitsi’s group synthesized the tetramers with
siloxane core [37]. Laschat and his co-workers prepared
the triphenylene tetramers with spiro-carbon spacer [35].
These tetramers were good liquid crystals with low
Introduction
Columnar discotic liquid crystals, possessing a rigid
polyaromatic cores with several peripheral alkyl chains,
have attracted much research interests in recent years
due to their extensive application prospects, such as
organic light-emitting diodes, organic photovoltaic cells,
one dimensional conductors, organic field-effect
transistors, gas sensors, photocopying machines, etc
o
o
phase transition temperatures (-60 C~-40 C), although
many room-temperature liquid crystals with one or two
triphenylene units were prepared. On the other hand, it
had been proved that the large rigid spacer and
hydrogen-bonding spacer could enhance obviously the
melt points of discotic liquid crystals [39-45]. For
examples, the rigid triazole bridges based on click
chemistry had been used efficiently to construct the
triphenylene liquid crystals with high phase transition
temperatures [16, 36, 46-47]. However, the influences
of rigid spacer and hydrogen-bonding spacer on the
mesophase of triphenylene tetramer were not reported
[1-4]. Triphenylene with six aliphatic arms were the
important discotic liquid crystals and exhibited high
tendency to form the required columnar phases [1-7].
Many triphenylene liquid crystals were synthesized and
their interesting mesomorphic properties were
investigated so far [8-21].
1

ACCEPTED MANUSCRIPT
so far. In this paper, we designed and synthesized three
respectively. The purifying process was simple with
recrystallization due to the high efficiency of
Schiff-base condensation.
novel triphenylene tetramers with, triazole bridges,
rigid aromatic Schiff-bases and hydrogen-bonding
spacers. Moreover, these novel triphenylene tetramers
showed excellent mesomorphic properties with melting
The structures of novel triphenylene tetramers 6, 7
and 8 were confirmed by IR, MS and NMR spectra (see
support information). The molecular ion peaks at
3788.3870, 3830.4638 and 3701.3946 in their HR-MS
spectra exactly agreed with the molecular weight of
compounds 6, 7 and 8, respectively. The deviations
o
points at 30~60 C, which was far higher than that of
previously reported triphenylene tetramers. This kind of
triphenylene liquid crystalline tetramers with melting
points near room temperature was observed for the first
time.
1
were less than 5ppm. In the H NMR spectra, all peaks
were assigned well for the corresponding proton of the
structures. On the other hand, one could see that,
although one singlet were observed for the CH=N
Schiff-base groups, some peaks for ArH, NH and
CH=N were sharp and the others were broad. These
phenomena might be explained by that compounds 6, 7
and 8 possessed the trans-isomer and cis-isomer, which
were usually observed for the Schiff-bonds. The
overlapped signals of protons for the very similar
structures of trans-isomer and cis-isomer resulted in the
Result and discussion
Synthesis and characterization
The synthetic routes for novel triphenylene tetramers
were illustrated in Scheme 1. In order to increase the
melting point of triphenylene liquid crystalline tetramer,
the four triazole rings and two rigid aromatic
Schiff-bases were introduced into the spacers. Also, the
aliphatic dihydrazide and p-phenylenediamine were
chosen as the condensation reagents for Schiff-base
reaction, because they could produce new hydrogen
bonds or enhance the rigidity of aromatic structures of
spacer, respectively. According to the literature method
1
broader peaks in H NMR spectra. Since the
trans-isomer is more stable than cis-isomer due to the
strong effect of steric hindrance, it was reasonable to
deduce that the tetramers adopted mainly in
trans-isomer.
[16], by reacting monohydroxytriphenylene 1 with
excess 1, 6-dibromohexane in K CO /MeCN system,
2
3
the ω-bromo-substituted triphenylene 2 was synthesized
in yield of 80%. Then by treating compound 2 with
NaN in DMF solution, the triphenylene derivative 3
3
containing azide group was prepared via the
nucleophilic substitution in yield of 95%. On the other
hand, 3,4-bis(prop-2-ynyloxy)benzaldehyde
obtained by reacting 3,4-dihydroxybenzaldehyde with
-bromoprop-1-yne in K CO / MeCN system in yield
4
was
3
2
3
4
3
of 86%. Subsequently, the coupling procedure of
compound 3 and compound 4 was carried out by the
classic click reaction of the Huisgen [2+3]
cycloaddition. Compound 5 was separated in yield of
65% after column chromatography. Furthermore, by
refluxing compound 5 with malonic dihydrazide, adipic
dihydrazide or p-phenylenediamine in mol ratio of 2:1
in solution of CHCl /MeOH(1:1, V/V), the target
3
triphenylene tetramers 6, 7 and 8, of which the spacer
possessed two Schiff-bases and two hydrogen-bonding
groups or with large rigid aromatic Schiff-base bridges,
were prepared in yields of 75%, 78% and 73%,
2

ACCEPTED MANUSCRIPT
o
OC5H11
115.7 C for cooling. Based on these DSC traces, two
OC5H11
C5H11O
C5H11O
phase transitions of solid state-mesophase and
mesophase-isotropic phase could be proposed for the
phase transition processes of compounds 6, 7 and 8.
The phase transition temperatures on heating were
higher a little than that on cooling. The hysteresis
phenomena could be attributed to the super-cooling
behaviors of such highly viscous materials. Compound
8 possessed higher phase transition temperatures than
that of compounds 6 and 7, indicating that the large
OC5H11
OC5H11
OH
NaN , DMF
3
Br-(CH2)6-Br
O(CH2)6-Br
K2CO3, CH3CN
C5H11O
C5H11O
C5H11O
OC5H11
OC5H11
OC5H11
2
1
OC5H11
OC5H11
O
O
C5H11O
CHO
4)
OC5H11
C H11O
(
5
CuI, N(C2H5)3
C5H11O
C5H11O
OC5H11
O(CH2)6
O(CH2)6-N3
C5H11O
N
N
N
OC5H11
OC5H11
N
N
O(CH2)6
N
O
O
3
5
C5H11O
OC5H11
CHO aromatic Schiff-base spacer in compound 8 was more
favorable for increasing the phase transition
temperature than the hydrogen bonds in compounds 6
and 7. The phase transition temperatures of compound 6
were slight higher than that of compound 7, which
might be ascribed to the influence of longer soft alkyl
spacer in compound 7. Usually, the melting points of
triphenylene tetramers were lower than that of their
monomeric and dimeric precursors. However, the phase
transition temperatures of three novel tetramers 6, 7 and
O
O
O
CH2Cl2
MeOH
5
+ H N
NH2
R
2
C
N
N
C
O
H
R
H
OC5H11
C5H11O
OC5H11
O(CH2)6
N
N
N
C5H11O
R =
OC5H11
O
O
O
HN
6
R =
N
N
,
7
NH
,
8
R =
H
H
O
o
Scheme 1 The synthetic route of triphenylene tetramers
, 7 and 8
8 (30~60 C) were similar to their precursor 5, and far
6
higher than the reported data of other tetramers
o
o
(
-60 C~-40 C). These results might suggest that the
Mesomorphic properties
The mesophase behaviors of tetramers 6, 7 and 8 were
rigid large aromatic Schiff-bases and hydrogen-bonding
spacers were favorable for enhancing the phase
transition temperatures, which were in accordance with
the results of other liquid crystals with rigid or
studied firstly by differential scanning calorimetry
(DSC) analysis. The DSC of their precursor 5 was also
3
6-42
investigated for comparison. The DSC traces and data
are shown in Figure 1 and Table 1, respectively. All of
them possessed two phase transition behaviors during
second heating and cooling, indicating the existence of
mesophase. Precursor 5 exhibited the mesomorphic
hydrogen-bonding spacers.
It was worthy of noting
that novel tetramers 6, 7 and 8 were the first examples
triphenylene tetrameric liquid crystals with phase
transition temperature near room temperature.
o
o
8
behaviors between 47.2 C and 95.3 C on heating, and
cooling
6
4
2
0
2
8
7
o
o
heating
3
2.3 C and 91.9 C on cooling. Comparing with
triphenylene dimer 5, tetramers 6, 7 and 8 also showed
similar mesomorphic temperatures. For compound 6,
cooling
heating
6
5
o
two endothermic peaks appeared at 43.4 C and 125.2
-
o
cooling
heating
C on heating and two exothermic peaks emerged at
-4
-6
o
o
3
6.2 C and 109.3 C on cooling. The corresponding
o
o
-
8
endothermic peaks at 38.9 C and 118.9 C upon
cooling
heating
o
-
10
heating and the exothermic peaks at 30.9 C and 108.2
-20
0
20
40
60
80
100
120
140
160
180
o
C upon cooling were observed for compound 7,
o
Temperature ( C)
respectively. Compound
8
displayed the phase
o
o
transition temperatures at 57.2 C and 136.9 C for
Figure 1 The DSC traces of compounds 5, 6, 7 and 8 on
o
o
-1
heating, following the exothermic peaks at 45.7 C and
second heating and cooling (scan rate 10 C min )
3

ACCEPTED MANUSCRIPT
o
Table 1 Transition temperatures ( C) and enthalpies
1.93
-1
(
kJ·mol ) of compounds 5, 6, 7 and 8
5
.21
Comp.
T(ΔH)
Heating
scan
6.4
2
5.90
3
.36
.90
3
Phase
Cooling
scan
8
7
6
1
.88
5
.10
2
6.18
[a]
transition
3
.30
3
.77
5
6
7
8
Cr-Col(Col-Cr)
Col-Iso(Iso-Col)
Cr-Col(Col-Cr)
Col-Iso(Iso-Col)
Cr-Col(Col-Cr)
Col-Iso(Iso-Col)
Cr-Col(Col-Cr)
Col-Iso(Iso-Col)
47.2(6.6)
95.3(7.2)
43.4(14.7)
125.2(13.8)
38.9(18.4)
118.9(17.9)
57.2(14.6)
136.9(10.8)
32.3(6.3)
91.9(5.9)
36.2(13.6)
109.3(10.7)
30.9(13.5)
108.2(12.4)
45.7(13.6)
115.7(11.2)
2.05
2
5.72
3
.57 5.44
.11
4
10
20
30
40
Scattering angle (2θ)
Figure 3 XRD traces of compounds 6, 7 and 8
o
measured at 80 C
Moreover, X-ray diffraction (XRD) analysis was
employed to study the mesophase structures of
compounds 6,
7
and
8 at the corresponding
[
a] Cr=crystalline, Col=columnar phase, Iso=isotropic
temperatures of mesomorphic states. The plots of
intensity versus 2θ were shown in Figure 3. In the
small-angle region, four reflections were observed for
The polarizing optical microscopy (POM) was
further used to investigate the mesomorphic textures of
o
o
o
o
tetramer 6 at 2.05 , 3.57 , 4.11 and 5.44 . Also, four
novel tetramers 6, 7 and 8. The obvious phase
o
o
o
o
o
o
peaks at 1.88 , 3.30 3.77 and 5.10 , or 1.93 , 3.36
transitions
of
solid
state-mesophase
and
o
o
3
.90 and 5.21 were distinguished for compounds 7
mesophase-isotropic phase were observed for them
heating and cooling. The temperatures of phase
transitions were approximately in accordance with the
corresponding thermic peaks of DSC traces. As cooling
slowly down from the isotropic phase, the typical defect
textures of columnar mesophase appeared gradually.
Figure 2 showed the mesomorphic textures of
and 8, respectively. After calculation, the d-spacings
derived from these angles were 43.06, 24.72, 21.48 and
1
1
6.23 Å for compound 6, 46.55, 26.75, 23.41 and
7.31Å for compound 7, 45.73, 26.27, 22.63 and 16.94
Å for compound 8, respectively. These data were in
agreement with the ratios of 1: 1/√3:1/√4: 1/√7,
indicating the [100], [110], [200] and [210] planes of
hexagonal lattice, respectively. In their wide angle
o
compounds 6, 7 and 8 at 80 C under POM (magnified
400 times). These textures were the typical focal-conic
o
regions, a broad peak at 17~27 and another narrow
textures, indicating the formation of columnar liquid
crystals.
o
peak at about 26 appeared obviously. The broad peaks
suggesting the d-spacings of 3.30~5.21 Å could be
attributed to liquid-like packing of alkyl chains. The
o
o
peaks at 25.72 for compound 6, 26.18 for compound 7
o
and 25.90 for compound 8 corresponded to the
spacings of 3.46, 3.40 and 3.44 Å, respectively. These
spacings were well in accordance with the
intracolumnar core-to-core distances in the hexagonal
mesophase. All these XRD analysis implied novel
tetramers 6, 7 and 8 were good hexagonal columnar
Figure 2 Mesomorphic textures of compounds 6, 7 and
o
8
obtained under POM on cooling at 80 C (×400)
4

ACCEPTED MANUSCRIPT
liquid crystals, which were consistent with the
All chemical reagents were obtained from commercial
suppliers and used without further purification. The
other organic solvents and inorganic reagents were
purified according to standard anhydrous methods
before use. TLC analysis was performed using
pre-coated glass plates. Column chromatography was
performed using silica gel (200-300 mesh). NMR
experimental results of POM and DSC data. Based on
these results, the aggregating representation in a disk
and the schematic representation of the hexagonal
columnar structure could be proposed in Figure 4. The
similar hexagonal columnar mesophase also was
observed for triphenylene tetramer with spiro-carbon
35
spacer in literature.
spectra were recorded in CDCl on a Bruker-ARX 400
3
o
instrument at 25 C. Chemical shifts are reported in ppm,
using tetramethylsilane (TMS) as internal standard. MS
spectra were obtained from Bruker MALDI-TOF mass
spectrometer. POM (Leica DMRX) was used along
with a hot stage (Linkam THMSE 600) to examine
phase transitions. Thermal analysis of the materials was
Samples 6, 7 and 8
carried out using DSC (Thermal Analysis Q100) at a
o
scanning rate of 10 C/min under N atmosphere. XRD
2
Columnar structure
experiments were performed on SEIFERT-FPM
(XRD7), using Cu Kα 1.5406Å as the radiation source
with 40 kV, 30 mA power. Compound 3 was prepared
by the method of literature [16]. Compound 4 was
synthesized according to the literature [48].
Figure 4 The proposed schematic representation of the
hexagonal columnar phases of compounds 6, 7 and 8.
Conclusion
In conclusion, three tetramers based on triphenylene
derivatives with triazole bridges, rigid aromatic
Schiff-bases and hydrogen-bonding spacers were
designed and synthesized in yield of 73~78%. Their
structures were confirmed by IR, NMR and MS. Their
mesomorphic properties were studied by DSC, POM
and XRD. These novel triphenylene tetramers showed
excellent mesomorphic properties with melting points
The synthetic procedure of compound 5
Under N atmosphere, the mixture of compound 3
2
(0.40g, 0.5mmol) and compound 4 (0.053g, 0.248mmol)
was stirred in 30 mL of DMF solution in the presence
of CuI (0.34g,1.5mmol) and triethylamine (0.3 mL).
o
The reaction system was carried out at 85 C for 24 h
with the TLC detection. After reaction, the solvent was
evaporated under reduced pressure. 30 mL of CHCl3
and 30 mL of distilled water were added with vigorous
stirring for half an hour. Then the organic layer was
separated and concentrated. The residue was purified by
column chromatography (eluant: petroleum ehter : ethyl
acetate=1:2, V/V) to afford white solid in yield of 65%.
o
at 30~60 C, which was higher than that of previous
reported triphenylene tetramers. They possessed the
good hexagonal columnar structure of mesophase. The
triphenylene liquid crystalline tetramers with melting
points near room temperature could be attributed to the
influences of rigid aromatic Schiff-bases and
hydrogen-bonding spacers. This research was a good
example of how to design and synthesize triphenylene
oligomers with special liquid crystalline properties by
tuning the structures of spacers.
-1
Compound 5: FT-IR(KBr), v/cm : 2933(C-H),
1
1746(C=O),1688(C=O). H NMR (400 MHz, CDCl )
3
δppm: 0.96 (t, 30H, J=6.8Hz, CH ), 1.41~2.02 (m, 76H,
3
CH ), 4.22 (bs, 24H, Tp-OCH ), 4.37 (bs, 4H, NCH ),
2
2
2
5.09 (bs, 2H, OCH Ar), 5.19 (bs, 2H, OCH Ar), 7.02(d,
2
2
1
H, J=6.8Hz, ArH), 7.43(s, 1H, ArH), 7.51(s, 1H, ArH),
7.66(d, 1H, J=6.8Hz, ArH), 7.70 (s, 1H, ArH), 7.78(s,
2H, TpH), 9.76 (s, 1H, CHO)..
Experimental
1
Material and Method
5

ACCEPTED MANUSCRIPT
+
The synthetic procedure of compounds 6, 7
and 8
C H N O30 [M+MeCN+Na] : 3830.4385, found:
228 322 16
3830.4638.
-1
Under N atmosphere, the mixture of compound 5
Compound 8: FT-IR(KBr), v/cm : 2939(C-H),
2
1
(0.36g, 0.2 mmol) and corresponding diamine or
1752(C=O),1601(C=N). H NMR (400 MHz, CDCl )
3
dihydrazide (0.1 mmol) were refluxed in 25 mL of
δppm: 0.97 (t, 60H, J=6.8Hz, CH ), 1.41~2.03 (m,
3
CHCl /EtOH (1:3, V:V) by using 0.2 mL of glacial
152H, CH ), 4.21 (t, J=8.0Hz, 48H, Tp-OCH ), 4.40 (t,
3
2
2
acetic acid as catalyst for 12h. TLC detection suggested
the disappearance of compound 5. After cooling, the
solution was cooled in refrigeratory overnight and then
the white precipitates were obtained. The white
precipitates were filtered and washed with small
amount of methanol. The crude product was further
purified by recrystallization with CH OH:CH Cl (4:1).
J=8.0Hz, 8H, NCH ), 5.14 (s, 4H, OCH Ar), 5.17 (s,
2 2
4H, OCH Ar), 6.96 (d, 2H, J=8.4Hz, ArH), 7.03(s, 2H,
2
ArH), 7.32 (d, 2H, J=8.0Hz, ArH), 7.38(s, 4H, ArH),
7.67 (s, 4H, ArH), 7.80(s, 24H, TpH), 8.65 (s, 2H,
1
3
N=CH). C-NMR(100MHz, CDCl ) δ (ppm): 158.48,
3
148.99, 148.95, 148.81, 148.70, 143.62, 143.56, 123.64,
123.59, 123.49, 123.02, 122.21, 121.75, 115.45, 113.37,
107.43, 107.30, 107.12, 69.72, 69.62, 69.47, 69.10,
50.14, 30.10, 30.06, 29.99, 29.61, 29.07, 28.29, 26.19,
3
2
2
Compounds 6, 7 and 8 were obtained as white solid in
the yields of 75%, 79% and 73%, respectively.
-1
Compound 6: FT-IR(KBr), v/cm : 2939(C-H),
26.07, 25.48, 25.40, 22.44, 14.00. Maldi-TOF-MS(m/z):
1
+
1
752(C=O),1601(C=N). H NMR (400 MHz, CDCl )
3701.4409, HR-MS calcd for C228H316N O [M+H] :
3
14 28
δppm: 0.97 (t, 60H, J=6.8Hz, CH ), 1.41~2.07 (m,
3701.3874, found 3701.3946.
3
1
52H, CH ), 4.10(s, 2H, COCH CO), 4.21 (bs, 48H,
2
2
Acknowledgment Financial support from the National
Natural Science Foundation of China (No: 21406036),
Fujian Natural Science Foundation of China (No.
Tp-OCH ), 4.39 (bs, 8H, NCH ), 5.18 (bs, 8H,
2
2
OCH Ar), 7.02(bs, 2H, ArH), 7.34 (d, 2H, J=8.0Hz,
2
ArH), 7.42(s, 2H, ArH), 7.70 (bs, 4H, ArH), 7.81(s,
2017J01571), and the Program for Innovative Research
2
4H, TpH), 9.02 (s, 2H, N=CH), 9.74 (s, 2H, NH).
1
3
Team in Science and Technology in Fujian Province
University were greatly acknowledged.
C-NMR(100MHz, CDCl ) δ (ppm): 172.36, 150.95,
3
1
1
1
5
2
3
49.81, 148.99, 148.94, 148.69, 148.56, 148.19, 143.28,
23.60, 123.48, 123.22, 122.73, 114.56, 114.36, 107.44,
07.30, 107.15, 107.01, 69.73, 69.63, 69.46, 69.05,
0.13, 50.00, 29.88, 29.62, 29.06, 28.28, 26.05, 25.89,
5.37, 25.30, 22.47, 14.00. Maldi-TOF-MS(m/z):
788.9546, HR-MS calcd for C225H316N O
References
1
. Laschat S, Baro A, Steinke N, Giesselmann F,
Hagele C, Scalia G, Judele R, Kapatsina E, Sauer S,
Schreivogel A, Tosoni M (2007) Discotic liquid
crystals: From tailor-made synthesis to plastic
electronics. Angew Chem Int Ed 46:4832-4887.
. Sergeyev S, Pisula W, Geerts YH (2007) Discotic
liquid crystals: A new generation of organic
semiconductors. Chem Soc Rev 36:1902-1929.
16
30
+
[M+MeCN+Na] : 3788.3916, found 3788.3870.
-1
Compound 7: FT-IR(KBr), v/cm : 2939(C-H),
1
1752(C=O),1601(C=N). H NMR (400 MHz, CDCl )
3
2
3
δppm: 0.97 (t, 60H, J=6.8Hz, CH ), 1.41~2.04 (m,
3
1
4
56H, CH ), 2.23 (t, J=8.0Hz, 4H, CH CO), 4.21 (bs,
2 2
8H, Tp-OCH ), 4.37 (bs, 8H, NCH ), 5.18 (bs, 8H,
2
2
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07.28, 107.15, 69.63, 69.47, 69.14, 50.16, 30.06, 29.61,
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4
4
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Highlights




Three novel triphenylene tetramers were
synthesized.
They possessed good columnar liquid
crystal behaviors.
The first room-temperature mesophase
were observed for triphenylene tetramers.
The mesomorphic properties could be
tuned by the structures of spacers.
10