Design, synthesis, and characterization of 1,3,5-Tri(1 H-benzo[d]imidazol-2-yl)benzene-based fluorescent supramolecular columnar liquid crystals with a broad mesomorphic range

Article abstract of DOI:10.1021/jo5016954

A new kind of supramolecular columnar liquid crystal T-A with a broad mesomorphic range (up to 164.9 °C), good thermal stability, and strong fluorescence is designed and formed by the H-bonding between 1,3,5-tri(1H-benzo[d]imidazol-2-yl)benzene (T) and serial gallic acid derivatives (A). Two components are easily available because of simple routes, common reactions, high yields, commercial starting materials, and inexpensive catalysts. The introduction of the 1,2,3-triazole structure into component A makes the textures different and is slightly disadvantageous for the T-A complexes.

Full text of DOI:10.1021/jo5016954

Article
pubs.acs.org/joc
Design, Synthesis, and Characterization of 1,3,5-
Tri(1H‑benzo[d]imidazol-2-yl)benzene-Based Fluorescent
Supramolecular Columnar Liquid Crystals with a Broad Mesomorphic
Range
Jin-Feng Xiong,†,⊥ Shi-He Luo,‡,⊥ Jing-Pei Huo,§ Jin-Yan Liu,† Shui-Xia Chen,*,‡ and Zhao-Yang Wang*,†
†School of Chemistry and Environment, South China Normal University, and Key Laboratory of Theoretical Chemistry of
Environment, Ministry of Education, Guangzhou 510006, P. R. China
‡PCFM & DSAPM Lab, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, China
§School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, P. R. China
S
* Supporting Information
ABSTRACT: A new kind of supramolecular columnar liquid
crystal T−A with a broad mesomorphic range (up to 164.9 °C),
good thermal stability, and strong fluorescence is designed and
formed by the H-bonding between 1,3,5-tri(1H-benzo[d]-
imidazol-2-yl)benzene (T) and serial gallic acid derivatives
(A). Two components are easily available because of simple
routes, common reactions, high yields, commercial starting
materials, and inexpensive catalysts. The introduction of the
1,2,3-triazole structure into component A makes the textures
different and is slightly disadvantageous for the T−A
complexes.
bonding between 1,3,5-tri(1H-benzo[d]imidazol-2-yl)benzene
(T) and gallic acid derivatives (A) are reported (Scheme 1).
Benzimidazole-type compound 1,3,5-tri(1H-benzo[d]imidazol-
2-yl)benzene is designed as a component of liquid crystal
materials for the first time, and two components are easily
available because of simple routes, common reactions, high
yields, commercial starting materials, and inexpensive catalysts
(Schemes 2 and 3).
1. INTRODUCTION
Self-assembly by H-bonding is an important method for
forming liquid crystals, and liquid crystals based on H-bonding
have many special advantages. In particular, they may exhibit
dynamic behaviors, such as charge or energy transportation,
information storing, and molecular sensing.1−3 At the same
time, columnar liquid crystals with the function of transferring
charge or energy are important photoelectric materials in many
fields, including solar cells.4−6 Thus, there is an increasing level
of interest in the study of columnar liquid crystals based on H-
bonding. Usually, most columnar liquid crystals are formed by
H-bonding in a one-component system.7−12
To further apply H-bonding to multifunctional columnar
liquid crystals, Sierra13−16 and other groups17−22 began to
investigate the two-component system. In particular, if there is
a fluorophore in one of the components, fluorescent columnar
liquid crystals can be achieved as potential photoelectric
materials.15,20 However, to the best of our knowledge, there are
only two reports of fluorescent supramolecular columnar liquid
crystals with a narrow liquid crystal phase based on H-bonding
in a two-component system, and the fluorophores are
introduced into the two-component system through lengthy
synthetic routes.15,20 Thus, it is still a challenge to develop a
new two-component system concisely and obtain liquid crystal
materials with better properties.
2. RESULTS AND DISCUSSION
2.1. Synthesis of Components T and A. Though 1,3,5-
tri(1H-benzo[d]imidazol-2-yl)benzene is designed as compo-
nent T for the first time (Scheme 1), this fluorescent core can
be easily prepared by the simple condensation of commercially
available o-phenylenediamine and trimesic acid (Scheme 2).
Furthermore, the one-step reaction is catalyzed by inexpensive
polyphosphoric acid, and the yield is 81%. In the literature
about two-component fluorescent supramolecular columnar
liquid crystals based on H-bonding, the synthesis of the
fluorescent component has many shortcomings, such as the
long synthetic route with a low total yield (the yield of three
steps is 52−56%),15 and even five steps (the yield of the target
molecule is 30−59%).20 What is worse is the fact that the
protection and deprotection steps are also needed,15,20 and
Herein, a new kind of fluorescent supramolecular columnar
Received: July 28, 2014
liquid crystals (T−A) with a broad mesomorphic range via H-
© XXXX American Chemical Society
A
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Scheme 1. Formation of Supramolecular Columnar Liquid Crystals Based on 1,3,5-Tri(1H-benzo[d]imidazol-2-yl)benzene
Scheme 2. Synthetic Route of Component T
At the same time, as component A, serial gallic acid
derivatives [A1−A7 (Scheme 1)] are prepared in good yields
through simple etherification, O-alkylation, Click reaction (for
only A5−A7, which are designed to investigate the influence of
the introduction of the 1,2,3-triazole structure into component
A on the properties of the T−A complexes as a comparison
because of the application of 1,2,3-triazole compounds in
columnar liquid crystals20,23), and hydrolysis reaction (Scheme
3), and the structures and purities of all T and A components
are verified well by 1H and 13C NMR, ESI-MS, FTIR, UV, and
elemental analysis (see the Supporting Information).
some steps require metal catalysis.20 Therefore, it is obvious
that, compared with the reported component,15,20 the
fluorescent core T in our design can be concisely obtained
with a higher yield in the absence of any metal catalyst.
2.2. Formation and Characterization of T−A Com-
plexes. Using the reported methods,13,15,18,20 the T−A
complexes are prepared, and their formation is studied via
FTIR and NMR spectroscopy. Taking T−A1 as an example
Scheme 3. Synthetic Route of Component A
B
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(Figure 1), the CO stretching vibration in A1 appears at 1683
carbonyl band in T−A1 is shifted to 1695 cm−1, which is lower
than that of the free carboxylic acid (1733 cm−1). These results
are similar to the corresponding results of the reported two-
component columnar liquid crystal system.13,15,18,20
cm−1, which indicates dimeric H-bonding.24 Conversely, the
Of course, the formation of H-bonding complexes as
1
designed is further confirmed by the H NMR investigation
(Figure 2; more figures and detailed discussions can be seen in
the Supporting Information). As anticipated, integral ratios of
proton peaks are consistent with both the theoretical value and
the molar feed ratios, and the proton signals involved in
complexation as well as those near the complexating groups
have field shifted in a correlated way (Figure 2), which is similar
to the previously reported result.13,15,18,20
2.3. Photophysical Properties and Thermal Stability.
According to the literature,20,25 the optical properties of the T−
A complexes are investigated in dilute CH2Cl2 solutions (1 ×
10−5 mol L−1 for the UV−vis absorption measurement and 1 ×
10−6 mol L−1 for the fluorescence measurement) at room
temperature. For the T−A1 complex, there are two absorption
peaks at 276 and 311 nm and an emission maximal wavelength
(λex) at 375 nm (Figure 3, left). When the 1,2,3-triazole
structure is introduced into component A, there is a similar
curve (Figure S3 of the Supporting Information), while the
Figure 1. FTIR spectra of A1 and T−A1.
1
Figure 2. H NMR spectra of A7, the T−A7 complex, and T in a CDCl3/DMSO-d6 mixture at a 1/1 volume ratio.
C
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Figure 3. Absorbance and emission spectra of the T−A1 complex (left) and photograph of the T−A1 complex in a CH2Cl2 solution under 365 nm
UV light (right).
corresponding data are different (268, 304, and 367 nm,
respectively) because of the difference in the structure of T−A7
(Scheme 1).
More importantly, in view of the intensity of the band, the
T−A1 complex has absorption and emission stronger than
those of the T−A7 complex (Figure S4 of the Supporting
Information), indicating that the T−A1 complex has photo-
physical properties relatively better than those of the T−A7
complex. Furthermore, the CH2Cl2 solution (1 × 10−4 mol
L−1) of the T−A1 complex shows very strong blue-green
emission under the 365 nm UV light (Figure 3, right).
Therefore, the T−A complexes can display a strong
fluorescence in solution, which make T−A complexes have a
potential application in photoelectric material.4−6,15
For the photoelectric material, thermal stability has an
important influence on its performance and lifetime.26 The
results of thermogravimetric analysis (Figure S5 of the
Supporting Information) are summarized in Table 1.
Figure 4. DSC curves of the T−A7 complex on the first cooling and
the second heating runs.
Table 1. Thermal Stability Data of the T−A Complexes
a
entry
complex
Td
which is similar to the results reported previously,15,20 but all
T−A complexes can show LC behavior over broad temperature
ranges [the largest range is 164.9 °C (Table 2)] with an
enantiotropic columnar phase.
Obviously, the temperature range of the LC phase is varied
for different components A. For components A1−A4, the T−A
complexes have a range of >159.6 °C. For A5−A7, the range of
the LC phase is relatively smaller and just >93.0 °C, which may
be related to the introduction of the triazole structure in
component A. Recently, there are only two reports about the
fluorescent supramolecular columnar liquid crystal based on the
H-bonding of two components. Their ranges of the LC phase
are 15.0 °C20 and 41.6 °C;15 both are obviously smaller than
the range of our T−A complexes.
The textures observed by POM (Figure 5), on cooling from
the isotropic liquid, are consistent with the presence of
columnar mesomorphism. Among them, the pseudo focal
conic fan-shaped textures as the typical columnar phase
textures29 are observed for the T−A complexes for components
A1−A4 (panels a−d, respectively, in Figure 5). For components
A5−A7, the T−A complexes have dendritic textures (panels e−
g, respectively, in Figure 5), which are also the typical columnar
phase textures.30 Thus, there is a difference between these
1
2
3
4
5
6
7
T−A1
T−A2
T−A3
T−A4
T−A5
T−A6
T−A7
281.2
285.9
289.7
293.6
244.2
249.9
258.3
a
Td is the temperature of a 5% mass loss.
Delightedly, in all cases, the Td, the temperature of a 5%
mass loss, is >244 °C, indicating that all T−A complexes have
good thermal stability. Upon comparison of entries 5−7 with
entries 1−4, it is obvious that the introduction of the triazole
moiety is disadvantageous for thermal stability. Even so, their
thermal stability still can be comparable to that of some one-
component H-bonding liquid crystals.27,28
2.4. Liquid Crystalline Properties. The liquid crystalline
(LC) behavior of the final T−A complexes is investigated by
polarizing optical microscopy (POM) and differential scanning
calorimetry (DSC) (a typical result is shown as Figure 4, and
others can be seen in the Supporting Information). Component
T or A does not exhibit liquid crystalline properties alone,
D
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Table 2. Phase Transition Temperatures (degrees Celsius) and Enthalpies (joules per gram, in parentheses) of T−A Complexes
a
a
complex
T−A1
T−A2
T−A3
T−A4
second heating
first cooling
Cr·50.4 (64.97)·Colr·208.9 (2.37)·I
Cr·56.6 (74.04)·Colr·215.8 (2.86)·I
Cr·75.2 (90.30)·Colr·229.9 (4.77)·I
Cr·66.4 (79.36)·Colr·220.3 (3.58)·I
Cr·117.7 (4.86)·Colh·222.5 (0.55)·I
Cr·124.4 (13.8)·Colh·239.6 (16.06)·I
Cr·146.0 (18.62)·Colh·248.1 (26.23)·I
−
I·201.5 (1.99)·Colr·36.6 (65.94)·Cr
I·208.6 (2.25)·Colr·44.8 (79.13)·Cr
I·217.8 (3.66)·Colr·58.2 (90.72)·Cr
I·210.5 (3.29)·Colr·49.6 (79.06)·Cr
I·207.8 (2.08)·Colh·114.8 (3.56)·Cr
I·225.9 (18.6)·Colh·114.2 (8.48)·Cr
I·232.2 (2.58)·Colh·131.3 (10.03)·Cr
I·38.1 (7.2)·Colr·23.1 (12.2)·Cr
I·111.6·Colr·70.0·g
T−A5
T−A6
T−A7
HBC-220
M-X12E1215
−
a
Abbreviations: Cr, crystalline; Colr, rectangular columnar mesophase; I, isotropic liquid; g, glassy state that maintains the mesophase organization.
Figure 5. Polarized optical micrographs of T−A complexes: (a) T−A1 at 128 °C, (b) T−A2 at 116 °C, (c) T−A3 at 112 °C, (d) T−A4 at 123 °C, (e)
T−A5 at 192 °C, (f) T−A6 at 197 °C, and (g) T−A7 at 203 °C.
textures, and those of the former four T−A complexes are due
to the introduction of the 1,2,3-triazole structure.
The existence of liquid crystalline mesophases of T−A
complexes is further confirmed by X-ray diffraction (XRD).
Taking T−A1 and T−A7 as the representative cases (Figures 6
and 7), their phases are analyzed. The ratio of the Bragg spacing
(d) at the small angles of the compounds in their mesophases is
not 1:1/2:1/3, indicating that their mesophases do not show a
Figure 7. XRD patterns of the T−A1 complex in the Col phase.
lamellar structure.24 Therefore, in combination with the POM
results described above, the phases of the T−A complexes are
columnar phases (Col).
For the general discotic liquid crystals, there are two main
types of Col phases with D6h (hexagonal) and D2h (rectangular)
symmetries.29 For the T−A7 complex (Figure 6), it shows one
diffraction peak with a d spacing of 39.1 Å and four weaker
features (22.5, 17.4, 14.8, and 11.3 Å) with a spacing ratio of 1:
Figure 6. XRD patterns of the T−A7 complex in the Col phase.
(1/3)1/2:(1/5)1/2:(1/7)1/2:(1/12)1/2 in the small angle region. A
E
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X-ray diffraction (XRD) studies were conducted at room temperature
with an X-ray diffractometer using Cu Kα radiation.14
broad halo centered at 4.4 Å and a peak at 3.9 Å are also
observed, which are assigned to the spacings between alkyl
chains and the central π-systems, respectively. Thus, the XRD
data of T−A7 in conjunction with the textural pattern suggest
that the mesophase is indeed the hexagonal columnar phase
(Colh).20 Similarly, the liquid crystal phases of T−A5 and T−
A6 are also Colh (Scheme 1).
The XRD pattern of the T−A1 complex in its LC phase
consists of two strong diffraction peaks with d spacings of 38.5,
28.2, and 14.1 Å in the small angle region, corresponding to the
(11), (20), and (40) reflections, respectively. A broad halo
centered at 4.2 Å and a peak at 3.7 Å are also observed (Figure
7), which are assigned to the spacings between alkyl chains and
the central π-systems, respectively. Thus, in combination with
the POM result of the T−A1 complex, this phase can be
assigned to rectangular columnar mesophases (Colr).24
Similarly, the liquid crystal phases of T−A1, T−A2, and T−
A3 are also Colr (Scheme 1).
4.2. Synthesis of Component Compounds T and A1−A7.
4.2.1. 1,3,5-Tri(1H-benzo[d]imidazol-2-yl)benzene (T). This com-
pound was synthesized as described in the literature:32 yellowish solid;
3.455 g, 81% yield (80%32); mp >300 °C; UV−vis (DMSO) λmax
1
316.0 nm; H NMR (400 MHz, DMSO-d6/TMS) δ 7.20−7.52 (m,
6H), 7.62−7.91 (m, 6H), 9.22 (s, 3H), 13.49 (s, 3H); 13C NMR (100
MHz, DMSO-d6/TMS) δ 112.2, 119.4, 122.4, 123.4, 125.9, 132.3,
+
135.8, 144.2, 150.8; ESI-MS calcd for C27H19N6 ([M + H]+) m/z
427.17 (100%), found m/z 427.31 (100%).
4.2.2. 3,4,5-Tris(dodecyloxy)benzoic Acid (A1). This compound
was synthesized as described in the literature:33 white powder; 1.843 g,
91% yield; mp 55.1−56.0 °C (56 °C33); 1H NMR (400 MHz, CDCl3/
TMS) δ 0.88 (t, J = 8.0 Hz, 9H), 1.27−1.35 (m, 48H), 1.44−1.52 (m,
6H), 1.72−1.86 (m, 6H), 4.01−4.06 (m, 6H), 7.33 (s, 2H); IR (film)
ν 3070, 2955, 2918, 2850, 1684, 1588, 1508, 1472, 1223, 1125, 867,
−
770, 720 cm−1; ESI-MS calcd for C43H77O5 ([M]−) m/z 673.58
(100%), found m/z 673.87 (100%).
4.2.3. 3,4,5-Tris(tetradecyloxy)benzoic Acid (A2). This compound
was synthesized as described in the literature:33 white powder; 2.050 g,
90% yield; mp 42.1−43.5 °C (56%, 43−45 °C34); 1H NMR (CDCl3/
TMS, 400 MHz) δ 0.88 (t, J = 8.0 Hz, 9H), 1.26−1.35 (m, 60H),
1.44−1.51 (m, 6H), 1.71−1.85 (m, 6H), 4.01−4.06 (m, 6H), 7.32 (s,
2H); ESI-MS calcd for C49H89O5− ([M]−) m/z 757.68 (100%), found
m/z 757.98 (100%).
3. CONCLUSION
In summary, a fluorescent core 1,3,5-tri(1H-benzo[d]imidazol-
2-yl)benzene (T) is concisely synthesized and can be
successfully designed to form supramolecular T−A complexes
through H-bonding with gallic acid derivatives (A). The
formation of T−A complexes is characterized by FTIR and
1H NMR. None of the T and A components present
mesomorphism, while all T−A complexes exhibit liquid
crystalline profiles. The mesophase properties are studied by
POM, DSC, and large and small angle X-ray scattering. Though
the introduction of 1,2,3-triazole structure into component A is
slightly disadvantageous, all T−A liquid crystal materials show a
tendency to exhibit columnar mesomorphism with a broad
temperature range (up to 164.9 °C). For the T−A complexes
with components A1−A4, rectangular columnar mesophases are
obtained. While for the T−A complexes with components A5−
A7, they show the hexagonal columnar mesophases. T−A
complexes have strong fluorescence in solution. Furthermore,
all T−A complexes display good thermal stability with a high
decomposition temperature (Td > 240 °C), and the Td of some
T−A complexes is near 300 °C. Thus, the T−A complexes are
characterized as highly organized, strongly fluorescent systems
with potential use in photoelectric materials. Also, this will
make us investigate the LC materials based on benzimidazoles.
In the future, the fluorescent properties of these two-
component system supramolecular columnar liquid crystals
will be further reported.
4.2.4. 3,4,5-Tris(hexadecyloxy)benzoic Acid (A3). This compound
was synthesized as described in the literature:33 white powder; 2.227 g,
88% yield; mp 75.4−77.0 °C (85%, 78 °C24); 1H NMR (CDCl3/TMS,
400 MHz) δ 0.91 (t, J = 8.0 Hz, 9H), 1.26−1.32 (m, 72H), 1.47−1.53
(m, 6H), 1.73−1.88 (m, 6H), 4.03−4.09 (m, 6H), 7.35 (s, 2H); ESI-
−
MS calcd for C55H101O5 ([M]−) m/z 841.76 (100%), found m/z
841.97 (100%).
4.2.5. 3,4,5-Tris(octadecyloxy)benzoic Acid (A4). This compound
was synthesized as described in the literature:33 white powder; 2.393 g,
86% yield; mp 47.4−48.9 °C (81%, 47−49 °C35); 1H NMR (CDCl3/
TMS, 400 MHz) δ 0.88 (t, J = 8.0 Hz, 9H), 1.25−1.30 (m, 84H),
1.44−1.59 (m, 6H), 1.71−1.87 (m, 6H), 4.00−4.05 (m, 6H), 7.31 (s,
2H); ESI-MS calcd for C61H113O5− ([M]−) m/z 925.86 (100%), found
m/z 925.97 (100%).
4.2.6. Methyl 3,4,5-Tris(prop-2-yn-1-yloxy)benzoate (3). This
compound was synthesized as described in the literature:36 white
37
1
powder; 2.595 g, 87% yield; mp 89.2−90.4 °C (93%, 89.4 °C ); H
NMR (CDCl3/TMS, 400 MHz) δ 2.46 (t, J = 4.0 Hz, 1H), 2.53 (t, J =
4.0 Hz, 2H), 3.91 (s, 3H), 4.80 (d, J = 4.0 Hz, 4H), 4.83 (d, J = 4.0 Hz,
+
2H), 7.47 (s, 2H); ESI-MS calcd for C17H15O5 ([M + Na]+) m/z
321.07 (100%), found m/z 321.28 (100%).
4.2.7. Methyl 3,4,5-Tris[(1-decyl-1H-1,2,3-triazol-4-yl)methoxy]-
benzoate (5a). A 50 mL flask was charged with intermediate 3
(0.460 g, 2 mmol), n-C10H21N3 4a (1.466 g, 8 mmol), 10% mmol of
Cu, and 5% mmol of CuSO4 in CH3CN (5 mL). The reaction mixture
was stirred at 25 °C for 48 h. After the reaction had reached
completion, the resulting mixture was extracted with ethyl acetate (3 ×
10 mL), and then the organic layer was washed several times with
distilled water. After the sample had been dried with anhydrous
MgSO4, the solvent was removed in vacuo. The crude product was
purified by column chromatography on silica gel with a gradient eluent
of mixtures of petroleum ether and ethyl acetate to afford pure sample
5a: white powder; 1.578 g, 93% yield; mp 103.4−104.1 °C; UV−vis
4. EXPERIMENTAL SECTION
4.1. General Information. All reagents and solvents were
commercially available and used as received. The alkyl azide
intermediate was prepared according to the reported procedures.31
Melting points were uncorrected. IR spectra were recorded with an
1
FTIR spectrometer. H and 13C NMR spectra were recorded with a
400 MHz NMR instrument in CDCl3 (or DMSO-d6, or their mixed
solvent) using TMS as an internal standard. Elemental analysis was
performed on an elemental analyzer. Mass spectra (MS) were
recorded on a mass spectrometer. UV−vis spectra were measured by
an ultraviolet absorption detector. The fluorescence spectra were
recorded with a spectrophotometer. The textures of the mesophases
were studied with an optical microscope with crossed polarizers.
Measurements of the transition temperatures were performed with a
thermal analyzer with a heating or cooling rate of 10 °C min−1.
Thermogravimetric analysis (TGA) was performed at a heating rate of
10 °C min−1 under a N2 atmosphere (flow velocity of 20 mL min−1).
1
(CH2Cl2) λmax 264.5 nm; H NMR (CDCl3/TMS, 400 MHz) δ 0.87
(t, J = 8.0 Hz, 9H), 1.23−1.34 (m, 42H), 1.84−1.87 (m, 2H), 1.89−
1.95 (m, 4H), 3.89 (s, 3H), 4.32 (t, J = 8.0 Hz, 2H), 4.36 (t, J = 8.0
Hz, 4H), 5.25 (s, 4H), 5.26 (s, 2H), 7.42 (s, 2H), 7.79 (s, 2H), 7.80 (s,
1H); 13C NMR (CDCl3/TMS, 100 MHz) δ 14.1, 22.63, 26.5, 29.0,
29.2, 29.4, 29.5, 30.2, 30.3, 31.8, 50.3, 50.5, 52.3, 63.3, 66.4, 109.3,
123.1, 123.8, 125.7, 141.6, 143.4, 144.0, 152.0, 166.3; IR (film) ν 3144,
3098, 2959, 2922, 2855, 1727, 1590, 1507, 1462, 1329, 1110, 1054,
837, 761, 721 cm−1; ESI-MS calcd for C47H78N9O5+ ([M + H]+) m/z
848.60 (100%), found m/z 848.77 (100%). Anal. Calcd for
F
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C47H77N9O5: C, 66.56; H, 9.15; N, 14.86. Found: C, 66.70; H, 9.20;
N, 14.72.
5b (0.932 g, 1 mmol) and a solution of NaOH (0.040 g, 1 mmol) in
60 mL of alcohol. After 1 mL of distilled water had been added, the
mixture was refluxed for 8 h. Then, the cooled mixture was acidified
with dilute HCl to pH 2−3, and the white crude product precipitated.
The subsequent recrystallization with anhydrous ethanol gave A6:
white powder; 0.817 g, 89% yield; mp 152.4−153.6 °C; UV−vis
4.2.8. Methyl 3,4,5-Tris[(1-dodecyl-1H-1,2,3-triazol-4-yl)-
methoxy]benzoate (5b). A 50 mL flask was charged with intermediate
3 (0.460 g, 2 mmol), n-C12H25N3 4b (1.691 g, 8 mmol), 10% mmol of
Cu, and 5% mmol of CuSO4 in CH3CN (5 mL). The reaction mixture
was stirred at 25 °C for 48 h. After the reaction had reached
completion, the resulting mixture was extracted with ethyl acetate (3 ×
10 mL), and then the organic layer was washed several times with
distilled water. After the sample had been dried with anhydrous
MgSO4, the solvent was removed in vacuo. The crude product was
purified by column chromatography on silica gel with a gradient eluent
of mixtures of petroleum ether and ethyl acetate to afford pure sample
5b: white powder; 1.770 g, 95% yield; mp 107.5−108.3 °C; UV−vis
1
(CH2Cl2) λmax 267.0 nm; H NMR (CDCl3/TMS, 400 MHz) δ 0.87
(t, J = 8.0 Hz, 9H), 1.22−1.35 (m, 54H), 1.83−1.88 (m, 2H), 1.91−
1.97 (m, 4H), 4.31 (t, J = 8.0 Hz, 2H), 4.36 (t, J = 8.0 Hz, 4H), 5.27
(s, 6H), 6.79 (b, 1H), 7.49 (s, 2H), 7.82 (s, 1H), 7.83 (s, 2H); 13C
NMR (CDCl3/TMS, 100 MHz) δ 14.1, 22.6, 26.5, 29.0, 29.2, 29.4,
29.5, 30.2, 30.3, 31.8, 50.4, 50.6, 66.0, 66.3, 109.7, 123.3, 123.9, 126.0,
141.8, 143.4, 144.0, 144.1, 151.9, 169.0; IR (film) ν 3442, 3146, 3093,
2957, 2922, 2855, 1695, 1588, 1504, 1464, 1321, 1112, 1049, 825, 797,
1
+
731 cm−1; ESI-MS calcd for C52H88N9O5 ([M + H]+) m/z 918.69
(CH2Cl2) λmax 264.0 nm; H NMR (CDCl3/TMS, 400 MHz) δ 0.88
(t, J = 8.0 Hz, 9H), 1.23−1.34 (m, 54H), 1.84−1.87 (m, 2H), 1.89−
1.94 (m, 4H), 3.89 (s, 3H), 4.30 (t, J = 8.0 Hz, 2H), 4.36 (t, J = 8.0
Hz, 4H), 5.25 (s, 4H), 5.26 (s, 2H), 7.42 (s, 2H), 7.79 (s, 2H), 7.80 (s,
1H); 13C NMR (CDCl3/TMS, 100 MHz) δ 14.1, 22.6, 26.5, 29.0,
29.3, 29.40, 29.5, 29.6, 30.2, 30.3, 31.9, 50.3, 50.5, 52.3, 63.3, 66.4,
109.3, 123.1, 123.8, 125.6, 141.6, 143.6, 144.0, 152.0, 166.3; IR (film)
ν 3145, 3096, 2955, 2922, 2852, 1726, 1593, 1500, 1469, 1329, 1113,
1053, 828, 761, 721 cm−1; ESI-MS calcd for C53H90N9O5+ ([M + H]+)
m/z 932.71 (100%), found m/z 933.04 (100%). Anal. Calcd for
C53H89N9O5: C, 68.28; H, 9.62; N, 13.52. Found: C, 68.18; H, 9.76;
N, 13.33.
(100%), found m/z 918.79 (100%). Anal. Calcd for C52H87N9O5: C,
68.01; H, 9.55; N, 13.73. Found: C, 68.19; H, 9.36; N, 13.60.
4.2.12. 3,4,5-Tris[(1-tetradecyl-1H-1,2,3-triazol-4-yl)methoxy]-
benzoic Acid (A7). A 100 mL flask was charged with intermediate
5c (1.016 g, 1 mmol) and a solution of NaOH (0.040 g, 1 mmol) in 60
mL of alcohol. After 1 mL of distilled water had been added, the
mixture was refluxed for 8 h. Then, the cooled mixture was acidified
with dilute HCl to pH 2−3, and the white crude product precipitated.
The subsequent recrystallization with anhydrous ethanol gave A7:
white powder; 0.902 g, 90% yield; mp 154.2−155.8 °C; UV−vis
1
(CH2Cl2) λmax 266.5 nm; H NMR (CDCl3/TMS, 400 MHz) δ 0.87
4.2.9. Methyl 3,4,5-Tris[(1-tetradecyl-1H-1,2,3-triazol-4-yl)-
methoxy]benzoate (5c). A 50 mL flask was charged with intermediate
3 (0.460 g, 2 mmol), n-C14H29N3 4c (1.915 g, 8 mmol), 10% mmol of
Cu, and 5% mmol of CuSO4 in CH3CN (5 mL). The reaction mixture
was stirred at 25 °C for 48 h. After the reaction had reached
completion, the resulting mixture was extracted with ethyl acetate (3 ×
10 mL), and then the organic layer was washed several times with
distilled water. After the sample had been dried with anhydrous
MgSO4, the solvent was removed in vacuo. The crude product was
purified by column chromatography on silica gel with a gradient eluent
of mixtures of petroleum ether and ethyl acetate to afford pure sample
5c: white powder; 1.911 g, 94% yield; mp 119.9−120.8 °C; UV−vis
(t, J = 8.0 Hz, 9H), 1.22−1.35 (m, 66H), 1.84−1.96 (m, 6H), 4.28−
4.40 (m, 6H), 5.28 (s, 6H), 6.41 (b, 1H), 7.50 (s, 2H), 7.82 (s, 3H);
13C NMR (CDCl3/TMS, 100 MHz) δ 14.1, 22.7, 26.5, 26.6, 29.0, 29.1,
29.3, 29.4, 29.5, 29.6, 30.3, 30.4, 31.9, 50.5, 50.7, 63.2, 66.5, 109.9,
123.4, 124.1, 125.7, 142.0, 143.4, 144.1, 152.0, 169.1; IR (film) ν 3451,
3140, 3089, 2955, 2919, 2848, 1700, 1593, 1507, 1466, 1320, 1119,
+
1054, 842, 764, 724 cm−1; ESI-MS calcd for C58H100N9O5 ([M +
H]+) m/z 1002.78 (100%), found m/z 1002.87 (100%). Anal. Calcd
for C58H99N9O5: C, 69.49; H, 9.95; N, 12.58. Found: C, 69.36; H,
9.86; N, 12.70.
4.3. Preparation of the T−A Complexes. Taking complex T−A1
as an example, we prepared the T−A complexes as follows.
Component T (0.0426 g, 0.1 mmol) was dissolved in 60 mL of
methanol by refluxing for 1 h, and then the solution of component A1
(0.2025 g, 0.3 mmol) in 10 mL of CHCl3 was added. The mixture was
refluxed for 4 h. After the solvent had evaporated in vacuo, drying in
vacuo gave complex T−A1 in a yield of 100%. According to a similar
method, the other six T−A complexes were also quantitatively
obtained.
1
(CH2Cl2) λmax 265.0 nm; H NMR (CDCl3/TMS, 400 MHz) δ 0.88
(t, J = 8.0 Hz, 9H), 1.24−1.36 (m, 66H), 1.84−1.87 (m, 2H), 1.89−
1.94 (m, 4H), 3.88 (s, 3H), 4.30 (t, J = 8.0 Hz, 2H), 4.36 (t, J = 8.0
Hz, 4H), 5.25 (s, 6H), 7.40 (s, 2H), 7.81 (s, 3H); 13C NMR (CDCl3/
TMS, 100 MHz) δ 14.1, 22.6, 26.4, 26.5, 29.0, 29.3, 29.4, 29.5, 29.6,
30.2, 30.3, 31.9, 50.2, 50.4, 52.2, 63.3, 66.4, 109.2, 123.1, 123.8, 125.6,
141.6, 143.3, 144.0, 152.0, 166.2; IR (film) ν 3151, 3096, 2953, 2918,
2850, 1719, 1593, 1507, 1468, 1328, 1108, 1053, 831, 761, 721 cm−1;
+
ESI-MS calcd for C59H102N9O5 ([M + H]+) m/z 1016.80 (100%),
Some typical characterization data of T−A complexes. For complex
1
T−A1: H NMR (CDCl3/TMS, 400 MHz) δ 0.85−0.91 (m, 27H),
found m/z 1016.89 (100%). Anal. Calcd for C59H101N9O5: C, 69.71;
H, 10.02; N, 12.40. Found: C, 69.58; H, 9.85; N, 12.52.
1.20−1.38 (m, 144H), 1.45−1.55 (m, 18H), 1.74−1.88 (m, 18H),
3.93−4.10 (m, 18H), 7.20−7.22 (m, 6H), 7.40 (s, 6H), 7.60−7.63 (m,
6H), 9.53 (s, 3H). For complex T−A7: 1H NMR (CDCl3/DMSO-d6/
TMS, 400 MHz) δ 0.85−0.89 (m, 27H), 1.24−1.27 (m, 180H), 1.29−
1.32 (m, 18H), 1.80−1.85 (m, 6H), 1.86−1.91 (m, 12H), 4.30 (t, J =
8.0 Hz, 6H), 4.37 (t, J = 8.0 Hz, 12H), 5.13 (s, 6H), 5.20 (s, 12H),
7.14−7.34 (m, 6H), 7.41−7.44 (m, 6H), 7.56−7.77 (m, 6H), 7.94−
7.96 (m, 3H), 8.06−8.09 (m, 6H), 9.14 (s, 3H), 13.01 (b, 6H).
Before being used in further test experiments, all T−A complexes
were heated to the isotropic state and then slowly cooled to room
temperature to make the mesophase completely formed according to
the literature.13,15,18,20
4.2.10. 3,4,5-Tris[(1-decyl-1H-1,2,3-triazol-4-yl)methoxy]benzoic
Acid (A5). A 100 mL flask was charged with intermediate 5a (0.848
g, 1 mmol) and a solution of NaOH (0.040 g, 1 mmol) in 60 mL of
alcohol. After 1 mL of distilled water had been added, the mixture was
refluxed for 8 h. Then, the cooled mixture was acidified with dilute
HCl to pH 2−3, and the white crude product precipitated. The
subsequent recrystallization with anhydrous ethanol gave A5: white
powder; 0.726 g, 87% yield; mp 149.2−150.6 °C; UV−vis (CH2Cl2)
1
λmax 267.5 nm; H NMR (CDCl3/TMS, 400 MHz) δ 0.87 (t, J = 8.0
Hz, 9H), 1.23−1.34 (m, 42H), 1.84−1.88 (m, 2H), 1.91−1.95 (m,
4H), 4.31 (t, J = 8.0 Hz, 2H), 4.36 (t, J = 8.0 Hz, 4H), 5.27 (s, 6H),
6.81 (b, 1H), 7.49 (s, 2H), 7.82 (s, 1H), 7.83 (s, 2H); 13C NMR
(CDCl3/TMS, 100 MHz) δ 14.1, 22.6, 26.5, 29.0, 29.2, 29.4, 29.5,
30.2, 30.3, 31.8, 50.4, 50.6, 63.0, 66.3, 109.7, 123.3, 123.9, 126.0, 141.8,
143.6, 144.0, 144.1, 151.9, 169.0; IR (film) ν 3456, 3141, 3090, 2959,
2922, 2853, 1700, 1593, 1507, 1464, 1328, 1123, 1051, 832, 768, 723
ASSOCIATED CONTENT
■
S
* Supporting Information
Some detailed discussions and explanations with supplied
+
cm−1; ESI-MS calcd for C46H76N9O5 ([M + H]+) m/z 834.60
1
figures and tables; H and 13C NMR and mass spectra of
(100%), found m/z 834.76 (100%). Anal. Calcd for C46H75N9O5: C,
66.23; H, 9.06; N, 15.11. Found: C, 66.39; H, 9.00; N, 15.28.
4.2.11. 3,4,5-Tris[(1-dodecyl-1H-1,2,3-triazol-4-yl)methoxy]-
benzoic Acid (A6). A 100 mL flask was charged with intermediate
1
compounds T, A1−A4, 3, 5a−5c, and A5−A7; and H NMR
spectra of typical T−A complexes. This material is available free
of charge via the Internet at http://pubs.acs.org.
G
dx.doi.org/10.1021/jo5016954 | J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry
Article
(23) Bhalla, V.; Gupta, A.; Kumar, M.; Shankar Rao, D. S.; Prasad, S.
K. ACS Appl. Mater. Interfaces 2013, 5, 672−679.
(24) Li, J. Z.; Tang, T.; Li, F.; Li, M. Dyes Pigm. 2008, 77, 395−401.
(25) Ye, Q.; Chang, J.-J.; Shao, J.-J.; Chi, C.-Y. J. Mater. Chem. 2012,
22, 13180−13186.
AUTHOR INFORMATION
Corresponding Authors
*E-mail: cescsx@mail.sysu.edu.cn.
*E-mail: wangzy@scnu.edu.cn. Telephone: 8620-39310258.
■
(26) Tao, Y.-T.; Yang, C.-L.; Qin, J.-G. Chem. Soc. Rev. 2011, 40,
2943−2970.
Author Contributions
⊥J.-F. Xiong and S.-H. Luo contributed equally to this work.
(27) Wiggins, K. M.; Kerr, R. L.; Chen, Z.; Bielawski, C. W. J. Mater.
Chem. 2010, 20, 5709−5714.
Notes
The authors declare no competing financial interest.
(28) Ji, S.-P.; Tang, M.; He, L.; Tao, G.-H. Chem.Eur. J. 2013, 19,
4452−4461.
(29) Yelamaggad, C. V.; Achalkumar, A. S.; Rao, D. S. S.; Prasad, S.
K. J. Org. Chem. 2007, 72, 8308−8318.
ACKNOWLEDGMENTS
■
We are grateful to the National Natural Science Foundation of
China (20772035), the 3rd Talents Special Funds of
Guangdong Higher Education (Guangdong-Finance-Education
[2011]431), and the Natural Science Foundation of Guang-
dong Province (S2011010001556) for financial support.
(30) Paquette, J. A.; Yardley, C. J.; Psutka, K. M.; Cochran, M. A.;
Calderon, O.; Williams, V. E.; Maly, K. E. Chem. Commun. 2012, 48,
8210−8212.
(31) Tan, Y.-H.; Li, J.-X.; Xue, F.-L.; Qi, J.; Wang, Z.-Y. Tetrahedron
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dx.doi.org/10.1021/jo5016954 | J. Org. Chem. XXXX, XXX, XXX−XXX