Self-assembly of bistriazole BDT based bolaamphiphiles into SmA phase and helical organogels

Article abstract of DOI:10.1016/j.molliq.2020.114521

Bistriazole benzo[1,2-b:4,3-b′]dithiophene (BDT) contained bolaamphiphiles have been synthesized via Sonogashira coupling and click reactions as key steps. For such compounds, the central bent bistriazole BDT core, the flexible methylene spacer led the rodlike core together with the terminal diol groups to twist to be U-shaped polar region. Micro-segregation of U-shaped polar region from the lipophilic chains generated a SmA phase. Furthermore, these compounds can act as super organogelators to gel different kinds of solvents with the lowest critical gelation concentration (CGC) of 0.2 mg/ml. Gel morphologies with scarcely reported nanostructures including nanofibers, nanobelts, nanodisks, nanotrumpets and nanotubes were firstly observed in bolaamphiphilic self-assembly system.

Full text of DOI:10.1016/j.molliq.2020.114521

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Self-assembly of bistriazole BDT based bolaamphiphiles into
SmA phase and helical organogels
Deling Zhang, Yuantao Liu, Hongfei Gao, Qi Yan, Xiaohong
Cheng
PII:
S0167-7322(20)35173-4
DOI:
https://doi.org/10.1016/j.molliq.2020.114521
MOLLIQ 114521
Reference:
To appear in:
Journal of Molecular Liquids
Received date:
Revised date:
Accepted date:
7 August 2020
22 September 2020
4 October 2020
Please cite this article as: D. Zhang, Y. Liu, H. Gao, et al., Self-assembly of bistriazole
BDT based bolaamphiphiles into SmA phase and helical organogels, Journal of Molecular
Liquids (2018), https://doi.org/10.1016/j.molliq.2020.114521
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Self assembly of bistriazole BDT based bolaamphiphiles into SmA
phase and helcial organogels
Deling Zhang,[a] Yuantao Liu,[a] Hongfei Gao,[a] Qi Yan[*b] and Xiaohong Cheng[*a]
[a] Key Laboratory of Medicinal Chemistry for Natural Resources, Yunnan University, Kunming,
P. R. China. E-mail: xhcheng@ynu.edu.cn
[b] Department of Neurosurgery, First Affiliated Hospital of Kunming Medical University,
Kunming, P. R. China. E-mail: kmyanqi@126.com
Keywords: self-assembly; liquid crystal; bolaamphiphiles; organogel; chiral morphology;
Abstract: Bistriazole benzo[1,2-b:4,3-b']dithiophene (BDT) contained bolaamphiphiles have been
synthesized via Sonogashira coupling and click reactions as key steps. For such compounds, the
central bent bistriazole BDT core, the flexible methylene spacer led the rodlike core together with
the terminal diol groups to twist to be U-shaped polar region. Micro-segregation of U-shaped
polar region from the lipophilic chains generated a SmA phase. Furthermore, these compounds
can act as super organogelators to gel different kinds of solvents with the lowest critical gelation
concentration (CGC) of 0.2 mg/ml. Gel morphologies with scarcely reported nanostructures
including nanofibers, nanobelts, nanodisks, nanotrumpets and nanotubes were firstly observed in
bolaamphiphilic self-assembly system.
1. Introduction
Self-assembly is an effective strategy for building complex supramolecular nanostructures from
simple components. The nanostructures constructed by self-assembly are essential for the
development of material and life sciences [1]. Liquid crystals (LCs) are fascinating materials
considering their properties, their significance for study the fundamental mechanism of molecular
self-assembly and their widely applications in commerce [2]. Till now, a large amount of complex
2D and 3D structures have been realized by LCs [3].
Low molecular mass organogelators (LMOGs) [4] repesent another self assembly system with
formation of well-defined nano/micro structures promoted by intermolecular noncovalent
interactions, including van der Waals forces, hydrogen bonds, π–π stacking and dipole–dipole
interactions between gelator-gelator and gelator-solvents. Such supramolecular gelation has
generated various interesting superstructures including helical structures relying on the properties
of gelators and solvents [5,6]. Such supramolecular gels have wide applications [7] as stimulus
response materials, templated catalysis and pollution treatment materials etc.
Bolaamphiphiles composed of three incompatible three blocks namely a rodlike aromatic core,
two terminal glycerol groups and one or two laterally lipophilic chains, are a class of successfully
designed mesogens being able to organize into a variety of polygonal honeycomblike mesophase,
a numerous of new layer and 3D liquid crystalline phases [3,8,9,10,11]. The eye-catching
honeycomb columnar phases are with core-shell structures where the alkyl chains self-assemble
into the soft cores, the conjugated rodlike units connected by hydrogen bonds between the
terminal glycerol groups act as shells surrounding the soft cores[3].
In order to realize the practical application of bolaamphiphiles, we have recently combined
several electrooptical or photoactive groups such as oligothiophenes [12], azobenzene [13],
2,1,3-benzothiadiazole (BTD) [14] and triazole [15] etc. into the rodlike aromatic cores of the
bolaamphiphiles. All such designed bolaamphiphiles can still self-assemble into honeycomb

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columnar phases promoted by the microsegregation of the three incompatible segments into
different regions. The gained self-assembly disciplines should be applied to direct their assembly
in a designed manner [16]. This might be very important for future applications of such
compounds as organic electro optical materials [12,17].
However, so far as the self-assembly of bolaamphiphiles is addressed, most work is focused on
their thermotropic LC behavior, there is only rare examples for the self-assembly of
bolaamphiphiles in organic solvents [13,14,18], the chirality of the supramolecular gel has never
been expressed.
Benzo[1,2-b:4,3-b′]dithiophene (BDT) as one of the ortho-annulated heteroaromatic rings has
been used to construct thiahelicenes [19,20,21], which could show superior chiro-optical and
electronic properties [22], and has found wide applications as chiral catalysts [23], chiral inducers
[24] and chiral ligand etc [19b]. Due to their highly aggregation tendency and good solubility for
film formation as well as attractive photovoltaic properties, BDT derivatives have been
extensively investigated.
Fig. 1. Here reported compounds BDT/n with transition temperatures and associated enthalpy (T/ °C [ ΔH / kJ
mol-1]) as confirmed by DSC (peak temperatures, 10 K min-1), values in parentheses are transition upon cooling;
abbreviations: Cr = crystalline solid; Iso = isotropic liquid state, SmA = Smectic A phase.
In order to get much deep insights into the basic mechamism about the self-assembly rules as well
as how the information imprinted in the molecular structures can be translated into the well
defined supramolecular assemblies involing both LC and gel states, herein we decided to construct
a novel kind of bolaamphiphiles BDT/n (Fig. 1) by combination of BDT unit together with
triazole units into the rodlike core, two lateral alkyl chains could be easily attached at the benzol
ring of central BDT. The self-assembly of these compounds both in bulk state and in solvent was
studied. The influence of the BDT and triazole units on the self-assembly behavior was also
discussed.
2. Results and Discussion
2.1 Synthesis
The BDT triazole based bolaamphiphiles BDT/n were prepared from 3,3'-bithiophene 1 via
two-fold acylation with oxalyl chloride, followed by reduction of o-quinone 2 with zinc/acetic
anhydride, and subsequent substitution with 1-bromoalkane and iodination with
N-iodosuccinimide [ 25 ]. Sonogashira coupling of 5/n with methyl-3-butyn-2-ol yielded
bis-isopropanol protected bisacetylenes 6/n, desilylation of 6/n produced the bisacetylenes 7/n
[26]. In another side 4-hydroxyl benzoate was etherified with allybromide. Then the ester group of

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8 was reduced by LiAlH4 to be benzyl alcohol. In the following step, the hydroxyl group of 9 was
substituted by chloride with SOCl2. Benzyl chlorides was substituted with sodium azide gave out
p-azidobenzene 11. After dihydroxylation of the double bonds of p-azidobenzene 11 with
OsO4/NMMNO, the CuAAC click reaction between p-azidobenzene glycerol and bisacetylenes
7/n gave out the target bolaamphiphiles BDT/n (Scheme 1).
Scheme 1. Synthesis of compounds BDT/n: Reagents and conditions: i) oxalyl chloride, 1, 2-dichloroethane,
84 °C, 72 h; ii) acetic anhydride, Zn, Et3N, CH2Cl2, RT, 4 h; iii) CnH2n+1Br, Cs2CO3, DMF, 90 °C, 48 h; iv) CH2Cl2,
NIS, acetic acid; v) methylbutynol, CuI, Pd(PPh3)2Cl2 NEt3, THF, N2, RT, 12 h; vi) KOH, Toluene, 90 °C , 12 h;
vii) Allyl bromide, K2CO3, CH3CN, 90 °C; viii) THF, LiAlH4; ix) THF, thionyl chloride; x) DMF, KI, NaN3,
.
50 °C; xi) osmium tetroxide, NMMNO, Acetone; xii) THF, CuSO4 5.H2O, t-BuOH, H2O, sodium ascorbate,
RT.
2.2 Mesomorphic properties
Together two BDT/n compounds were synthesized. Their thermotropic liquid crystalline
properties were investigated by polarized optical microscopy (POM), differential scanning
calorimetry (DSC) and X-ray diffraction (XRD). Both compounds were enantiotropic LCs. The
melting temperature changed little whereas the clearing temperature increased with elongation of
the lateral chains (Figs. 1 and S2).
o
Under POM, heating the samples to 126 C, textures with pseudoisotropic regions and oily
streaks which were typical for Smectic A phases were observed (Figs. 2a and S1, Tables S1 and
S2). The pseudo isotropic regions indicated a uniaxial lamellar phase. The Smectic A phases were
further confirmed by XRD investigation, three intense sharp reflections in the ratio of 1 : 2 : 3,
indexed as (100), (200) and (300) were observed in the small angle region (Figs. 2b and S3). The
diffused halo at d = 0.44 nm (Fig. S4) corresponded to the mean lateral distances between the
molecules in the LC state. The layer distances of the SmA phases for compounds BDT/12 and
BDT/18 were d = 4.54 and 4.89 nm, respectively (Tables 1, S1 and S2). The layer spacing was
increasing with the elongation of the lateral chain, indicating that the lateral chain should be
related to the layer spacing. Considering the bulky and bend bistriazole BDT central unit, the
flexible methylene spacing, and the possible hydrogen bondings between the triazole and diol end
groups as well as hydrogen bondings between the diol groups, such bolaamphiphiles should be
considered as no longer triblock but as diblock molecules (Fig. 2c), in which the two lateral alkyl

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chains belonged to the lipophilic part, the rest of the molecular part was totally classified to the
polar part. Driving force for the molecular self-assembly into layer structure is the
microsegregation of the lipophilic part from the polar part. It should be mentioned that the
molecules could take different conformations (Fig. S5), but during the self-assembly, the actual
conformation could be changed to favor the packing. The rodlike core together with the two
terminal diol groups of this molecule could take a U-shape as shown in Fig 2c. Because the layer
spacing of this SmA phase is measured to be 4.41 nm for BDT/12 (Figs 2c and S6), which is
smaller than the value obtained from SAXS (d = 4.54 nm) (Tables S1), indicating a strongly
intercalated bilayer layer structures in which both the U-shaped aromatic cores with the glycerol
groups as well as the alkyl chains are intercalated as shown in Fig. 2c. Such packing satisfied the
optimal space filling and the maximum interactions (H-bond between the triazole and diol groups,
and π-π stacking etc) simultaneously. Further the H-bond between the triazole and the terminal
glycerol group is confirmed by the FT-IR experiments (Fig. 3). In solid state, the FT-IR spectrum
of representative compound BDT/12 showed two characteristic peaks at 1516 cm-1 and 3429 cm-1,
which could be assigned to N=N stretching vibration of triazole unit and O-H stretching vibration
of diol respectively. Whereas in LC state, the peaks showed obvious blue-shift (from 1516 to 1511
cm-1 and from 3429 to 3198 cm-1), indicating that H-bond existed between N atoms of triazole unit
and diol group [27].
(a)
(b)
(c)
Fig. 2. LC phase of representative compound BDT/12: a) texture of the SmA phase under POM at T = 140 °C
cooling from isotropic state; b) SAXS pattern of the SmA phase at T = 137 °C; c) possible molecular self-assembly
model of the SmA phase.

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Fig. 3. FT-IR spectra of BDT/12 in solid state and LC state.
It should be mentioned that all of the till now reported functional bolaamphiphiles[3,12,13,14,15]
which could form honeycomb columnar phases owned a certain length of conjugated unit in the
rodlike core. For examples, for BTD (2,1,3-benzothiadiazole) based bolaamphiphiles BTD/n[14]
(Fig. 4), which contained a large polycyclic aromatic hydrocarbon BTD central unit, but had
thiophene phenyl unit at each side, the long conjugated cores in such molecules allowed BTD/n to
form stable honeycomb phases (Fig. 4b). Even for triazole contained bolaamphiphiles 3/n (Fig.
4a), although the triazole and flexible methylene units were introduced, the central conjugated
2,5-bipheny thiophene unit could still allow the formation of square honeycomb phases. However
for herein reported BDT based bolaamphiphiles BDT/n, the π-conjugation of the rodlike core is
interrupted by flexible methylene spaces, and the possible temporary H-bond between the triazole
core with the terminal glycerol groups could disturb the separation of the rodlike core from the
terminal diol groups. Therefore, during self-assembly process, the central bent bistriazole BDT
core, the flexible methylene spacer forced the rodlike core together with the terminal diol groups
to twist to be U-shape which further separated from the lipophilic chains, and the molecules
further organized into SmA phase.
(a)
(b)
Fig. 4. a) The molecular structures of the previously reported bolaamphiphiles BTD/n and 3/n; b) model shows the
cross-section of the square honeycomb perpendicular to the cylinder long axis; blue: aromatic cores; red: glycerol
groups; the space in the cells between the aromatic cores is filled by the lateral alkyl chains (black).
2.3 Gelation behavior and characteristics
The gelation ability of the compounds BDT/n was studied according to the method of “inversion
tube test” [28]. BDT/n could generate organogels in polar solvents such as acetone, ethyl acetate
and alcohols, but was insoluble in less polar solvents such as 1,4-dioxane and nonpolar solvents
such as petroleum ether and hexane. Interesting the critical gelation concentration (CGC) of
BDT/18 in all cases is extremely low, therefore BDT/18 can be considered as a kind of

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superorganogelator (Table 1).
Table 1. Gelation characteristics and CGCs of BDT/n in different organic solvents[a]
Solvent
Petroleum ether
n-Hexane
BDT/C12
P
BDT/C18
P
P
P
Dichloromethane
Chloroform
Ethyl acetate
THF
G (2)
G (4)
G (3.8)
S
G (1.3)
G (2)
G (2.1)
S
Acetonitrile
1,4-Dioxane
Toluene
G (10)
S
G (0.6)
S
S
S
Acetone
S
G (1.9)
G (5)
G (1.5)
G (0.2)
DMSO
G (20)
G (5)
G (4)
Ethanol
Methanol
[a] S: soluble; G: gel; P: precipitate. CGC: critical gelation concentration (mg/mL).
(a) (c) (e)
(b)
(d)
(f)
Fig. 5. Selected SEM images of xerogels formed by BDT/12: a), b) in DCM (with different magnifications); c), d)
in EA; and e), f) in MeOH.
The morphologies of the xerogels of BDT/n were investigated by scanning electron microscopy
(SEM). Take the gel morphologies of compound BDT/12 as illustrative examples to study the
influence of the solvent polarities on the gel morphologies (Fig. 5). Xerogel from DCM showed
spherical structures with an average diameter of 20-30 μm, but the surface of the sphere is totally
blurred coexisting with some amorphous ribbons (Figs. 5a and 5b). Spherical structures can be
also observed in the xerogel from EA (Figs. 5c and 5d), however the spheres are in different sizes
with an average diameter of 5-11 μm. The spheres are largely deformed and grouped tightly, and
the surface of the sphere shows more clear textures than those of xerogel from DCM. Finally, the
morphologies of xerogel from MeOH show also cluster sphere morphologies (Figs. 5e and 5f),

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however the surface of the cluster is clearly composed of entangled helical fibers with the width
about 35-160 nm and the length about several microns. Obviously polar solvents have stronger
interaction with the molecules which led to more ordered morphologies. The interaction between
the solvent and triazole units, the hydrogen bondings between the triazole and diol units, π-π
interactions, as well as van der Waals forces etc. should play an important role in the aggregation
of the compounds in solvents. The different morphologies of the xerogels formed in different
solvents maybe ascribed to the effect of solvent polarities on the noncovalent interactions driving
the self-assembly [29].
The tangled helical nanofiber morphologies of the xerogel from BDT/12 in MeOH enhanced us
to dope the system with chiral small molecule -Phenylalanine (L-Phe) [30] with the purpose to
L
obtain novel helical superstructure. BDT/12 was mixed with -Phe in a molar ratio of 1 : 2,
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unfortunately no chiral superstructure is induced by such doping. Contrary the helical fibers
changed into non helical ribbons with a width ranging from 0.15-0.75 um and a length of tens of
microns after doping (Fig. S8b). We then turned our attention to compound BDT/18 which owned
much longer alkyl chain than BDT/12. The morphologies of the xerogel from BDT/18 in
methanol showed only nanobelt structures with a width ranging from 0.11-0.31 um and a length of
tens of microns (Fig. 6a). To our satisfy, after BDT/18 doped with L-Phe in a molar ratio of 1 : 2,
twist nanobelts with a width ranging from 0.11-0.71 um and a length of tens of microns were
observed (Fig. 6b).
(a)
(b)
Fig. 6. Selected SEM images of xerogels formed in CH3OH of a) BDT/18; b) BDT/18 and L-Phe.
The most interesting is the xerogel of BDT/18 from CH3CN which showed a morphologie with
entangled nanofibers with the width about 0.12-0.72 um and a length of tens of microns as shown
in Fig. 7a. After doping with -Phe, nanotwist belts, nanotrumpets, nanodisks and nanotubes
L
which were scarcely reported [31] in self-assembly systems before are observed as shown in in
Figs. 7b-f and S8.

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(a)
(b)
(c)
(d)
(e)
(f)
Fig. 7. a) SEM images of xerogel of BDT/18 from CH3CN; b-f) SEM images of different regions of the same
xerogel by doing BDT/18 with L-Phe in CH3CN.
Fig. 8. FT-IR spectra of BDT/18 and co-gel of BDT/18/L-Phe formed in CH3OH and CH3CN.
To further understand the interaction between -Phe and BDT/18, the FT-IR spectra of the
L
xerogels formed by BDT/18 in CH3OH and CH3CN respectively, as well as BDT/18/ L-Phe in
CH3OH and CH3CN respectively were performed (Fig. 8). IR of BDT/18 in CH3OH and CH3CN
exhibited characteristic vibration bands at 3433 cm-1 and 1518 cm-1 which were ascribed to O-H
and N=N stretching bands, respectively. For IR of co-gels of BDT/18/L-Phe, after BDT/18
interacted with -Phe in CH3OH, the stretching vibrations of O-H and N=N of BDT/18 showed
L
weak blue shifts from 3433 to 3429 cm-1 and 1518 to 1505 cm-1, respectively. As for co-gel of
BDT/18/ -Phe in CH3CN, the FT-IR spectra showed similar transition that the stretching
L
vibration bands O-H and N=N of BDT/18 shifted to lower wave numbers. These indicated
stronger hydrogen bonding between BDT/18 and L-Phe.
To clarify the evolution of these nanostructures, XRD was also performed for the xerogels (Fig.
9). The XRD pattern of the xerogel of BDT/18 from CH3CN showed three diffraction peaks with
d-spacing values 4.55 (001), 2.31 (002), and 1.53 (003) nm in a ratio of 1 : 1/2 : 1/3, revealing an
organization of an interdigitated or tilted monolayer structure with a layer distance of d = 4.55 nm
(Fig. 9a). While by doping with L-Phe in CH3CN, three diffraction peaks with d-spacing values at
4.66 (001), 2.28 (002), and 1.56 (003) nm in a ratio of 1 : 1/2 : 1/3, suggesting an organization of
an interdigitated or tilted monolayer structure with a layer distance of d = 4.66 nm (Fig. 9b). The
diffused peak at 4.23 and 4.13 nm for both xerogels respectively indicated the partially disordered

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alky chains, while the extra peak at 3.90 nm for xerogel by doping with -Phe suggested the
L
existence of stronger π-π stacking interaction in such gel state.
(a)
(b)
Fig. 9. (a) XRD images of xerogels formed in CH3CN by a) BDT/18; b) BDT/18 doping with L-Phe.
(a)
(b)
Fig. 10. CD spectra of xerogels of a) formed in CH3OH of BDT/12 (black line) and BDT/18 (red line); b) formed
in CH3CN (black line) and CH3OH (red line) of BDT/18/ L-Phe.
Circular dichroism (CD) spectroscopy was also carried out to study whether asymmetrical
aggregations occurred in the xerogels (Fig. 10). The gel of BDT/18 in CH3OH was CD-silent,
suggesting no helical assemblies. On the contrary, obvious negative Cotton effects at about 220
nm and a bisignal Cotton effect with the crossover at 313 nm were observed in the gel of BDT/12
in CH3OH. For co-gels of BDT/18 with -Phe in CH3OH, a strongly negative Cotton effects at
L
about 206 nm and an obvious bisignal Cotton effect with the crossover at 284 nm is observed in
CH3OH. Whereas a negative Cotton effects at about 298 nm were observed for the co-gels of
BDT/18 with -Phe in CH3CN. This is consistent with the test results of SEM. This CD
L
investigation indicated that all the helical gel morphologies exhibited asymmetric arrangements
through supramolecular gelation with preferential left handedness in all these assemblies.
Based on the above investigation, the possible formation mechanism of gels with nanotwists
and nanotrumpets etc was supposed in Fig. 11. Firstly the neighboring molecules organized into a
lamellar structure via the intermolecular H-bond and π–π stacking. In polar solvents, the layers
might further aggregated into nanotwists or nanobelts by additional interaction between gelator
and solvent such as dipole dipole and H-bond interactions. By doping with -Phe, the nanobelts
L
can twist further into a spring-like nanostructures. As the degree of twisting increasing, the twist

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spring-like nanostructures gradually rolled to form nanodisks, nanotrumpets and nanotubes. Both
right- and left-handed twists could be simultaneously observed during such process, but they
showed net CD activity ascribed to the unequal number of both twists (Fig. 10). It should be
mentioned that morphologies with twist nanotrumpets and nanotubes were scarcely observed in
self-assembly systems [32]. The H-bond among -Phe and diol and triazole units were enhanced
L
as revealed by the FT-IR measurements (Fig. 8), which increased the molecular packing, resulting
in twisting and curling of the nanofibers. The co-existence of nanotrumpets and nanobelts
indicated the formation mechanism clearly demonstrated by the SEM images shown in Figs. 7b-f.
Fig. 11. Schematic illustration of the possible formation processes of twist nanobelts, nanodisks and nanotubes via
co-assembly of BDT/18 with L-Phe respectively.
3. Conclusion
Therefore we have demonstrated that bolaamphiphiles composed of a large bend polycyclic
aromatic hydrocarbon BDT as a central core with two triazole links directly attached at each side
as well as flexible methylene spaces in the rodlike core are pseudo triblock bolaamphiphiles but
actually diblock amphiphiles, they could not provide the conjugated cores demanded for the
formation of honeycomb phases as well established for previously reported ternary
bolaamphiphiles. Instead the rodlike core together with the two terminal diol groups would form a
U-shape polar region, and an antiparallel packing of the molecules with intercalation of aliphatic
chains and U-shaped polar region respectively led to the formation of SmA phase. Such packing
satisfied both the optimal space filling and the maximum interactions. Most interesting, these
compounds can act as super organogelators with extremely low CGC to gel different organic
solvents. The various helical nanostructures with various excotic nanostructures including
nanofibers, nanobelts, nanodisks, nanotrumpets and nanotubes, which were firstly observed in
bolaamphiphilic self-assembly system indicating that the characteristics of BDT and triazole units
imprinted in the molecules have been partially successfully transferred into the LC and especially
into supramolecular gel systems. Therefore, BDT combined with triazole could be considered as a
new generation of super organogelators.

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Acknowledgements
This work was supported by National Natural Science Foundation of China (Nos. 21865038
and 21664015) and program for Innovative Research Team (in Science and Technology) in
University of Yunnan Province for financial supports (2018FY001(-012)). The calculations were
performed with the support of the Yunnan University Supercomputer Centre. We thank beamline
1W2A at Beijing Accelerator Laboratory and beamline BL16B1 at Shanghai Synchrotron
Radiation Facility (SSRF), China.
Conflicts of interest
There are no conflicts to declare.
References

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Conflicts of interest
The authors declared that they have no conflicts of interest to this work.

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CRediT author statement
Deling Zhang: Synthesis the compounds, property investigation and experimental part writing
Yuantao Liu: Property investigation and Gel model drawing
Hongfei Gao: Property investigation and LC model drawing
Qi Yan: Writing- Reviewing
Xiaohong Cheng: Conceptualization, Methodology, draft preparation and writing- Reviewing

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Graphical abstract

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Highlights:
Bolaamphiphilesbased onbistriazole BDTcore have been synthesized.
They displayed only SmA phase due to the U shaped polar region.
They can act as super-organo-gelators to form gels with exotic helical nanostructures.
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