A supramolecular self-assembly material based on a quinoline derivative and its sensitive response toward volatile acid and organic amine vapors

Article abstract of DOI:10.1039/c8nj00753e

A new gelator 1, containing a quinoline group, was designed, synthesized, and fully characterized. It was found that a stable organogel of 1 could be obtained in some solvents, including ethanol, acetonitrile, n-hexane, petroleum ether, and DMSO. It is wo

Full text of DOI:10.1039/c8nj00753e

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Supramolecular self-assembly material based on quinoline derivative
and sensitively response toward volatile acid and organic amine
vapors
Xinhua Cao*ab, Qianqian Dinga, Aiping Gaoa, Yiran Lia, Xueping Changa, Yongquan Wu*c
aCollege of Chemistry and Chemical Engineering
Mineral in the South of Henan, Institute for Conservation and Utilization of Agro-bioresources in Dabie
Mountains Xinyang Normal University, Xinyang 464000, China
＆Henan Province Key laboratory of Utilization of Non-metallic
，
bState Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P.R. China
E-mail: caoxhchem@163.com
cSchool of Chemistry and Chemical Engineering, Gannan Normal University, Ganzhou, Jiangxi 341000, P. R.
China. E-mail: wyq@gnnu.edu.cn
Abstract: A new gelator 1 contained quinoline group was designed, synthesized and fully characterized. It was
found that stable organogels 1 could be obtained in some solvents including ethanol, acetonitrile, nꢀhexane,
petroleum ether and DMSO. It was worth mentioning that supraꢀgel was formed in hexane and petroleum ether
with the critical gel concentration of 0.16% and 0.17%, respectively. The selfꢀassembly process of gelator 1 in the
above five solvents was carefully investigated by FESEM, UVꢀvis, FL, FTIR, XRD and water contact angle
experiments. It was found that gelator molecule 1 could selfꢀassembled into different selfꢀassembly structures with
different surface wettability from superꢀhydrophilicity to superꢀhydrophobicity in the selfꢀassembly process.
Organogel 1 formed in acetonitrile could emit strong light comparing with that of organogels 1 in the other four
solvents under the stimulation of 365 nm light. At the same time, the fluorescence emission of organogel state had
a redꢀshift of 70 nm comparing with that of solution state. The fluorescence emission of molecule 1 in solution and
gel state was further and well verified via theoretical calculation. The fluorescence emission of gelator 1
acetonitrile solution could reversibly respond to TFA and TEA along with the change of maximum emission
wavelength between 382 nm and 458 nm in turn. The xerogel 1 formed in acetonitrile exhibited sensitively
responsive ability towards TFA and TEA. More interesting, the different change behavior of the fluorescence
emission of molecule 1 in solution and xerogel state under responsive towards TFA and TEA. This research will
provide a new way for designing multiꢀfunctional soft matter for response volatile acid and organic amine vapors.
Keywords: supramolecular chemistry, selfꢀassembly, gel, volatile acid, organic amine

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Introduction
Supramolecular gels have obtained a great development over the past few decades due to their wide potential
application in many fields such as sensor, liquid crystals, lightꢀharvesting system, cell culture, catalysis, pollutant
removal, drug delivery and materials science1ꢀ9. Supramolecular gels can be formed under the driving force of
noncovalent interactions including πꢀπ stacking, hydrogenꢀbonding, electrostatic forces, hydrophobic interactions,
van der Waals forces, coordination interactions, chargeꢀtransfer, and so on10, 11. On the base of noncovalent
interactions, supramolecular gels could be prepared into multiꢀstimulation responsive materials via introduction of
different functional groups which can be responsive to external stimuli such as metal ions, biomolecule, light, pH,
enzymes, and redox agents, ultrasound, heat, electricity, mechanical action and magnetism12, 13. Many functional
groups were introduced into molecular structure and constructed supramolecular gel system including
carbohydrates, peptides, cholest, ureaꢀderivatives, long alkyl chain and simple fatty acids114ꢀ17. Simultaneously,
low weight organic molecule can be selfꢀassembled into various supramolecular architectures such as core–shells,
fibers, tubes, ribbons, balls, vesicles, films and honeycombs which can immobilize and then gelate a large volume
of solvents in their three dimensional networks18. In this respect, we have recently reported a novel class of
supramolcular gels based on naphthalimides derivatives with the sensing ability towards nitroaromatic compounds
or organic amine19ꢀ21
.
Volatile acids such as hydrochloric acid and trifluoroacetic acid (TFA) can be harmful to the body. For
example, they can give rise to bronchial spasm, inflammation, oedema, chemical pneumonia, pulmonary edema
and death if inhalation22, 22. Organic amines as important raw materials or intermediates are widely used in
chemical industry, food and fine chemical engineering24. Volatile organic amines such as triethylamine (TEA) and
aniline are important gaseous pollutants because they seriously damage the ecological environment and cause
severe threats to human health25. Recently, several supramolecular selfꢀassembly system exhibited the detection
ability of aromatic amine or acid vapors. Xue and coworkers have reported an cyanoꢀsubstituted vinylacridine
derivatives linked with NꢀdodecylꢀLꢀphenylalaninamide through succinyl (PC2VA) and glutaryl (PC3VA) groups
which could quantitatively detect aromatic amine and volatile acid vapors caused by the low HOMO energy level
of the fluorophore and the existence of the acridine moiety as an acid binding site26. We have prepared an
organogel system based on an iridium complex and a Eu (III) hybrid with the ability of responsive volatile acid
and organic amine vapors27.
Quinoline derivatives were widely used to be designed as fluorescence sensor or complex ligand due to their
excellent coordination ability toward metal ions28, 29. Zhang and Li reported a series of 3d transition metal

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complexes with a julolidine–quinoline based ligand and studied their structures, spectroscopy and optical
properties30. Song and coworkers reported a quinolin oximes with ability of selective and visual detection of a
nerve agent mimic by phosphorylation and protonation31. Fan and Yang reported a simple quinolone Schiffꢀbase
containing CHEF based fluorescence ‘turnꢀon’ chemosensor for distinguishing Zn2+ and Hg2+ with high sensitivity,
selectivity and reversibility32. Inspired by the previous works, a new selfꢀassembly system based on quinoline
derivative was designed (Scheme 1). The molecule could be selfꢀassembled into organogels in some solvents and
exhibit AIE during gelation in acetonitrile solvent. The fluorescence emission peaks of compound 1 acetonitrile
solution could have a large difference of 77 nm before and after addition of TFA. At the same time, the
fluorescence emission of compound 1 acetonitrile solution could reversibly transform back the original state after
addition of TEA. The fluorescence emission of the xerogel of the compound could be sensitively responded
towards acids and aromatic amines through different fluorescence emission change behavior. Thus, this smart
supramolecular selfꢀassembly system may provide a new method of designing excellent multiꢀresponsive soft
matter for detection of gaseous analytes.
C12H25
C12H25
O
OC12H25
O
N
O
O
H
Ν
N
Η
O
Scheme 1 Molecule structure of compound 1.
Experimental
Reagents and materials
2ꢀbromoquinoline, 4ꢀhydroxyphenylboronic acid, methyl 4ꢀbromobutanoate, ethaneꢀ1,2ꢀdiamine and gallicin
were all purchased from Shanghai Titan Scientific Co., Ltd. N,N'ꢀDicyclohexylcarbodiimide (DCC),
1ꢀhydroxybenzotriazole (HOBt), trifluoroacetic acid, lithium hydroxide monohydrate and triethylamine were
provided by Zhengzhou Alfa chem Co., Ltd. All other reagents were analytically pure.
The gelation test
The compound and solvent were put in a septumꢀcapped test tube and heated (>80 °C) until the solid was
dissolved. The sample vial was then cooled to 25 °C (room temperature). Qualitatively, gelation was considered
successful if no sample flow was observed upon inversion of the container at room temperature (the inverse flow
method)33. Xerogels were obtained by evaporation of solvent from the gel via freeze drying.
Instrumentation conditions

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1H NMR and 13C NMR spectra were recorded on a BrukerꢀAvance (Bruker, Ltd., Switzerland), at 400 and
100 MHz, respectively. Proton chemical shifts are reported in parts per million downfield from tetramethylsilane.
HRMS was recorded on a LTQꢀOrbitrap mass spectrometer (ThermoFisher, San Jose, CA, USA). Field emission
scanning electron microscope (FESEM) images were obtained using a FEꢀSEM Sꢀ4800 instrument (Hitachi, Ltd.,
Tokyo, Japan). Samples were prepared by spinning the samples on glass slices and coating with Pt. Powder Xꢀray
diffractions were generated by using a Philips PW3830 (Philips, Ltd., Eindhoven, Holland) with a power of 40 kV
at 40 mA (Cu target, λ = 0.1542 nm). UV–vis absorption spectra were recorded on a UVꢀvis 2550 spectroscope
(Shimadzu, Ltd., Tokyo, Japan). Fluorescence spectra were recorded on an Edinburgh Instruments FLS 900
(Edinburgh Instruments, Ltd, Livingston, UK). Fourier transform infrared (FTIR) spectra were collected using a
Nexus 470 spectrometer (Nicolet Company) with a resolution of 2 cm−1, and 32 scans were accumulated to obtain
an acceptable S/N ratio. The samples were prepared with KBr pellets. Original spectra were baselineꢀcorrected
using Omnic 5.1 software. The optimized structures and fluorescence emission of molecule 1 and the dimer 1 with
were determined with the help of theoretical calculations, in the framework of density functional theory (DFT)
calculations at the level of B3LYPꢀD3/6ꢀ31G* in a suite of Gaussian 09 programs.34
Results and discussion
The synthesis and characterization of quinoline derivative 1 is described in the Supporting Information. The
gelation behavior of compound 1 was evaluated in various organic solvents by a normal heatingꢀcooling process. It
was found that the stable organogels were formed in ethanol, acetonitrile, nꢀhexane, petroleum ether and DMSO
with the critical gel concentration (CGC) of 3.17%, 0.45%, 0.16%, 0.17% and 0.57%, respectively. The organogel
in petroleum ether was transparency, and the other four organogels were opaque (Figure S1). It was worth
mentioning that the CGC of organogels 1 in nꢀhexane and petroleum ether was lower than 0.2 wt.%, and falled
into the category of superꢀgelators35ꢀ37. The solutions 1 were obtained in methanol, DMF, toluene, THF, CH2Cl2
and CHCl3 after the hot solutions were cooled to room temperature. The compound 1was existed as the form of
precipitate in 1,4ꢀdioxane, acetone and ethyl acetate. The organogels 1 formed in the five solvents could be stable
for several months. When the organogels were under 365 nm light, they could emit different intensity light. The
organogels 1 formed in ethanol, hexane, petroleum ether and DMSO only emitted weak light. On the contrary, the
orgnaogel 1 in acetonitrile could emit strong light. For fluorescence chemosensor, the excellent fluorescence
behavior provided a good platform for application in sensor field through fluorescence change.

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Table 1 The gelation ability of molecule 1 in different solvents.a
Solvent
methanol
ethanol
3-57
S
G (3.17%)
DMF
S
acetonitrile
1,4ꢀdioxane
nꢀhexane
acetone
G (0.45%)
P
G (0.16%)
P
toluene
S
ethyl acetate
petroleum ether
DMSO
P
G (0.17%)
G (0.57%）
THF
S
S
S
CH2Cl2
CHCl3
S = solution; P = precipitate; G = gel; the values in the brackets denote the CGC.
Low weight organic molecule could be selfꢀassembled into the different morphologies under the driving force
of the noncovalent interaction. The selfꢀassembly structures of 1 in five kinds of solvents were investigated one by
one through field emission scanning electron microscopy (FESEM). Nanofibers structure was observed in
organogel 1 in ethanol with the length of tens of microns and width of about 300 nm (Figure 1a). The similar fibers
structure was found in organogel 1 in acetonitrile with the length of tens of microns and width of about 400 nm
(Figure 1b). The wrinkled structure with many irregular pores inlaying it was formed in organogel 1 in nꢀhexane
(Figure 1c). A relatively smooth film structure was formed in the selfꢀassembly process of compound 1 in
petroleum ether (Figure 1d). The similar fishing net structure knitted by nanofibers was observed in organogel 1 in
DMSO (Figure 1e). From the above results, it showed that compound 1 could selfꢀassemble into different structure
in different solvents.

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Figure 1 SEM images of orgnaogels 1 in different solvents of ethanol (a), acetonitrile (b), nꢀhexane (c), petroleum ether (d) and DMSO
(e). The scale bars for images a, b, c, d and e are all 10 ꢁm. The organogel concentration was all at their CGC.
UVꢀvis absorption spectra of solution and gel state could provide the information about the selfꢀassembly
process. The UVꢀvis absorption spectra of compound 1 in solution and gel state were carried out and showed in
Figure 2. The UVꢀvis absorption spectrum of solution 1 in ethanol showed two absorption bands at 270 and 332
nm which should be assigned to the nꢀπ* electron transition of quinoline group (Figure 2a)38. Comparing with 1
ethanol solution, the two absorption bands of gel 1 in ethanol at 271 and 332 nm did not have any obvious shift
expect for two new absorption bands at 348 and 379 nm appearing. The absorption bands of gel 1 in acetonitrile
were at 263, 343 and 382 nm (Figure 2b). The absorption band at 263 nm had a blueꢀshift of 7 nm, and the
absorption band at 343 had a redꢀshift of 11 nm comparing with that of 1 acetonitrile solution which showed that
πꢀπ stacking interaction existed in gel state. For solution and gel 1 in hexane, the UVꢀvis absorption spectra
exhibited the similar absorption behavior, and there was no shift between solution and gel state (Figure 2c). The
UVꢀvis absorption spectrum of 1 in petroleum ether solution had three absorption bands at 270, 332 and 350 nm.
The UVꢀvis absorption bands of organogel 1 in petroleum were broadened without any shift (Figure 2d).

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1.0
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
c
a
b
gel in ethanol
ethanol solution
gel in acetonitrile
acetonitrile solution
gel in n-hexane
n-hexane solution
0.8
0.6
0.4
0.2
0.0
250
300
350
400
450
500
250
300
350
400
450
500
250
300
350
400
450
500
Wavelength / nm
Wavelength / nm
Wavelength / nm
d
e
1.0
1.0
gel in pertroleum ether
gel in DMSO
DMSO solution
pertroleum ether solution
0.8
0.6
0.4
0.2
0.8
0.6
0.4
0.2
0.0
0.0
250
300
350
400
450
500
250
300
350
400
450
500
Wavelength / nm
Wavelength / nm
Figure 2 UVꢀvis absorption spectra of 1 in solution and gel state from different solvents of ethanol (a), acetonitrile (b), nꢀhexane (c),
petroleum ether (d) and DMSO (e). The solution concentration of 1 was all 10ꢀ5 M. The organogel concentration was all at their
corresponding CGC.
For organic functional materials, fluorescence emission behaviors were very important properties. The
fluorescence emission spectra of compound 1 in solution and gel state from different solvents were studied and
showed in Figure 3. The compound 1 in ethanol solution and gel state formed in ethanol all emitted 382 nm light
under the excitation of 332 nm light which showed no obvious πꢀπ stacking in gel state (Figure 3a). For compound
1 in acetonitrile solution, it could also emit 382 nm light under the same condition (Figure 3b). When compound 1
was selfꢀassembled into organogel 1 in acetonitrile, organogel 1 in acetonitrile exhibited different fluorescence
emission behavior with the two emission peaks at 385 nm and 495 nm which showed the πꢀπ stacking interaction
existed in gel state. In order to understand the fluorescence behavior change in its gel state, the fluorescence
emission of single molecule and dimer of 1 was investigated via theoretical calculation (Figure S2). The theoretical
calculation results showed the fluorescence emission peak of the single molecule 1 was located at 367 nm, and that
of the dimmer of 1 was at 467 nm which clearly verified the fluorescence emission behavior of molecule 1 in
solution and gel stated. The molecule distance in the dimer of 1 was about 3.37 Å. When compound 1 in hexane
was selfꢀassembled into organogel 1, the maximum fluorescence emission peak was redꢀshifted from 380 nm of 1
hexane solution to 386 nm33. For organogels 1 from petroleum ether and DMSO, the maximum fluorescence
emission peak was all at 385 nm, and the fluorescence emission peak of their corresponding solution was still
basically at 385 nm without any obvious shift.

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gel in acetonitrile
1.0
0.8
0.6
0.4
0.2
0.0
acetonitrile solution
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
b
a
c
gel in n-hexane
n-hexane solution
gel in ethanol
ethanol solution
350
400
450
500
550
600
350
400
450
500
550
600
350
400
450
500
550
600
Wavelength / nm
Wavelength / nm
Wavelength/nm
1.0
e
1.0
d
gel in petroleum ether
petroleum ether solution
gel in DMSO
DMSO solution
0.8
0.6
0.4
0.2
0.0
0.8
0.6
0.4
0.2
0.0
350
400
450
500
550
600
350
400
450
500
550
600
Wavelength / nm
Wavelength / nm
Figure 3 Fluorescence emission spectra (λex = 332 nm) of 1 in solution and gel from different solvents of ethanol (a), acetonitrile (b),
nꢀhexane (c), petroleum ether (d) and DMSO (e). The solution concentration of 1 was all 10ꢀ5 M. The organogel concentration was all at
their corresponding CGC.
FTꢀIR spectrum could provide some important information of the selfꢀassembly system, especially for
hydrogen bonding interaction. The FTꢀIR spectra of xeorgels 1 formed different solvents were investigated one by
one (Figure 4). As showed in Figure 4, the broadbands of NꢀH stretching vibration of xerogels 1 formed in hexane,
acetonitrile, ethanol, petroleum ether and DMSO were at 3293, 3293, 3289, 3293 and 3285 cmꢀ1, respectively
which indicated of possible hydrogen bonding39. For C=O stretching vibration in xerogel from hexane, acetonitrile,
ethanol, petroleum ether and DMSO, the C=O stretching vibration bands of xeorgels 1 formed in different solvents
were at 1639, 1639, 1634, 1639 and 1639 cmꢀ1, respectively which further proved the hydrogen bonding
interaction existed in selfꢀassembly system40.
xerogel from hexane
1639
1639
3293
3293
xerogel from acetonitrile
xerogel from ethanol
1643
1639
3289
3293
xerogel from petroleum ether
xerogel from DMSO
3285
1639
3500 3000 2500 2000 1500 1000 500
Wavenumber / cm-1
Figure 4 FTIR spectra of xerogels 1 from different solvents. The organogel concentration was all at their corresponding CGC.
To provide further information about the selfꢀassembly behavior, dried xerogels 1 formed from the five
solvents were subjected to powder Xꢀray diffraction (Figure 5). The scattering pattern of xerogel 1 in ethanol

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shows broad peaks in the wide angle range corresponding to dꢀspacing of about 0.98 nm and 0.42 nm, closely to
equivalent patterns for xerogels 1 derived from acetonitrile, hexane and petroleum ether (Figure 5a). The XRD
patterns of xerogel 1 in acetonitrile, hexane and petroleum ether exhibited the diffraction peaks with the
corresponding spacing of about 0.98nm, 0.41nm, 1.01nm, 0.42nm, 1.02nm and 0.42 nm, respectively (Figure
5bꢀ5d). It was different that XRD pattern of xerogel 1 formed in DMSO showed a series of peaks with the
dꢀspacing of 2.13 nm, 1.07 nm, 0.64 nm and 0.43 nm (Figure 5e). To a large extent, the ratio of the dꢀspacing of
2.13 nm, 1.07 nm and 0.43 nm follows the proportion 1: 1/2: 1/4, suggesting that the gelators were combined into a
bilayer arrangement41. According to the above experiments results, the probably packing mode of gelator was
speculated and listed in Figure 6. The molecule 1 was firstly stacking into a fibre structure, the fibres were further
intertwined and formed threeꢀdimensional network.
xerogel from ethanol
d=0.42nm
xerogel from acetonitrile
d=0.41nm
300
250
200
150
100
50
600
500
400
300
200
100
xeorgel from hexane
d=0.42nm
c
a
b
500
400
300
200
100
d=1.01nm
d=0.98nm
d=0.98nm
5
10
15
20
25
30
5
10
15
20
25
30
5
10
15
20
25
30
2
θ
/ degree
2θ / degree
2θ / degree
300
250
200
150
100
50
xeorgel from petroleum ether 250
d=0.42nm
d
d=2.13nm
e
xerogel from DMSO
d=0.43nm
200
150
100
50
d=0.64nm
d=1.07nm
d=1.02nm
5
10
15
20
25
30
5
10
15
20
25
30
2
θ
/ degree
2θ / degree
Figure 5 XRD patterns of xerogels 1 in solution and gel from different solvents of ethanol (a), acetonitrile (b), nꢀhexane (c), petroleum
ether (d) and DMSO (e). The solution concentration of 1 was all 10ꢀ5 M. The organogel concentration was all at their corresponding CGC.
Figure 6 The probably selfꢀassembly mode of molecule 1.
It was well known that materials surface wettability was decided by the composition of the material itself and
materials surface roughness which was one important property which also reflected the selfꢀassembly behavior of

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the surface layer42ꢀ45. For supramolecular selfꢀassembly system, a various of strucutres could be obtained in the
selfꢀassembly process such as nanofibre, tube, ribbon, piece, sphere, vesica and film. The different wettability
could be observed in supramolecular selfꢀassembly system, even if in a single component selfꢀassembly system.
For example, the nanofiber strucutre was observed in organogel 1 drived from five solvents (Figure 1), but the
strucutre surface wettability was completely different as showed in Figure 7. The xeorgel 1 film surface formed in
ethanol had some hydrophobicity with water contact angle of 98.5°. On the contrary, the xerogel 1 film surface
formed in acetonitrile exhibited high hydrophobicity with the water contact angle of 147°. When xerogel 1 film
surfaces formed in nꢀhexane and petroleum ether were subjected to water contact angle experiment, they also
exhibited some weak hydrophobicity with the water contact angle of 94° and 92°. Xerogel 1 film surfaces formed
in DMSO also exhibited high hydrophobicity with the contact angle of 146.° (Figure 7e). From the above results,
selfꢀassembly of compound 1 was utilized a different mode in different solvent.
Figure 7 Water contact angle experiments results of the film coating with gel 1 from different solvents of ethanol (a), acetonitrile (b),
nꢀhexane (c), petroleum ether (d) and DMSO (e). The organogel concentration was all at their corresponding CGC.
The fluorescence emission change of compound 1 in acetonitrile solution was investigated under response to
volatile acid and organic amine. Firstly, the selectivity of compound 1 towards volatile acid and organic amine was
investigated in solution state. As showed in the Figure 3S a, the fluorescence emission intensity of solution 1 was
decreased with the addition formic acid, hydrochloric acid, acetic acid, propionic acid and trifluoroacetic acid
(TFA). In the five kinds of acid, it was different that the fluorescence emission peak at 381 nm was completely
disappeared, and a new emission peak at 460 nm was appeared under addition of TFA which exhibited compound
1 had a good selectivity toward TFA. For solution 1 with addition of TFA, the emission peak at 381 nm could be
come back under addition of diethylamine, ethylenediamine, TEA and ammonia which showed solution 1 with
addition TFA could respond to aliphatic amine (Figure 3Sb). When the same amount of aniline was added to

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solution 1 with addition of TFA, the fluorescence emission change did not like the other organic amine and not
return to its original emission properties of solution 1 which showed that solution 1 with addition of TFA dully
responded toward aniline.
The trifluoroacetic acid (TFA) and triethylamine (TEA) was selected as volatile acid and organic amine,
respectively. As showed in Figure 8a, the fluorescence emission intensity at 382 nm was gradually decreased, a
new emission peak at 458 nm was appeared and the emission intensity was gradually increased accompanying
with a well defined isosbestic point at 431 nm. When 0.11 eq. of TFA was added to 1 acetonitrile solution, the
fluorescence emission did not change and reached the terminal point (Figure 8a). Plotting the fluorescence
intensity change of 1 at 381 nm as a function of 1/ [TFA] (1/ [IꢀIo] vs 1/ [TFA]) gave a linear curve. The binding
constant was determined to be 7.53 × 106 M−1 (the details showed in the SI, figure S4). The detection limit was
5.68×10ꢀ9 M (Table S1 and Figure S5 in the SI). In order to prove the reversibility of fluorescence emission of
compound 1, the fluorescence emission of 1 solution with addition of 0.11 eq. of TFA was further investigated
under further addition of TEA (Fiugre 8b). With addition of TEA, the fluorescence emission intensity at 382 nm
was gradually recovered and the fluorescence emission intensity at 458 nm was gradually decreased. As showed in
Figure 8c, the fluorescence emission could be reversibly transformed between 382 nm and 458 nm at least for 6
times. It was well Known that fluorescence sensor is especially attractive for recognition of analytes because its
fast, realꢀtime responses and high sensitivity and without inexpensive equipment23. The supramolecular
selfꢀasembly gel materials with aggregationꢀinduced emission (AIE) properties could have great potential
application via the formation of luminescent aggregation, to make up for the shortcoming of no emission in
solution state. Herein, xerogel 1 film formed in acetonitrile was used to respond to volatile acid and organic amine
vapors (Figure 8d). The fluorescence emission of xerogel 1 had the similar emission behavior like that of
organogel 1 in acetonitrile except for the relative decreasing at the fluorescence emission intensity of peak at 382
nm. When xerogel 1 respond to TFA, the fluorescence emission peak at 494 nm was disappeared in one minute. At
the same time, the fluorescence emission properties of xerogel 1 also could be recovered in one minute after
removing of TFA. The fluorescence emission change process of xerogel 1 under response to TFA was made into a
movie 1 as the supporting information. When xoergel 1 with response to TFA was further responded to TEA, the
fluorescence emission peak of xerogel 1 was shifted from 383 nm to 436 nm in one minute which showed that
fluorescence emission of xerogel 1 was disturbed by triethylamine trifluoroacetate formed in the response process.
The fluorescence emission change process of xerogel 1 under response to TFA and TEA was made into a movie 2
as the supporting information. From the above experiment results, the xerogel 1 film could fast respond to TFA and

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TEA. In this work, xerogel 1 could emit different light under response to TFA and TEA, not like the turnꢀon
fluorescence xerogel film sensor.
160
140
120
100
80
300
250
200
150
100
50
a
b
1 Solution
0.015 eq. TFA
0.02
0.025
0.03
0.035
0.04
0.045
0.06
1 solution +0.11 eq. TFA
+0.01Eq TEA
+0.02
+0.03
+0.05
+0.075
+0.10
+0.125
+0.15
60
0.07
0.09
0.11
40
20
0
0
350
400
450
500
550
600
350
400
450
500
550
600
Wavelength / nm
Wavelength / nm
xerogel 1
xerogel 1+TFA
xerogel 1+TFA+TEA
c
460
440
420
400
380
1.0
0.8
0.6
0.4
0.2
0.0
d
TEA
TFA
350
400
450
500
550
0
1
2
3
4
5
6
7
Wavelength / nm
Circle (times)
Figure 8 (a) Fluorescence emission change of 1 acetonitrile solution under titration of TFA; (b) Fluorescence emission change of 1
acetonitrile solution with addition of 0.11 eq. of TFA under titration of TEA; (c) Fluorescence emission reversibility cycle number of 1
acetonitrile solution under addition of TFA and TEA; (d) Fluorescence emission change of xerogel 1 from acetonitrile after response to
TFA and TEA.
Conclusion
The present results showed that the organogels 1 could be formed in five kinds of solvents by the new gelator
based on derivative. The organogels 1 from five kinds of solvents were characterized by FESEM, UVꢀvis, FL,
XRD, FTIR and water contact angle experiment. The results indicated that different selfꢀassembly behavior were
observed in different solvents, and formed different structure with different wettability from superꢀhydrophilicity
to superꢀhydrophobic under. Hydrogenꢀbonding interaction could be found by FTIR spectra of xerogels 1. The
organogel 1 drived from acetonitrile could emit much stronger light than that of organogels formed in the other
four solvents. Interestingly, compound 1 acetonitrile solution could reversibly respond to TFA and TEA, and
accompanied by the reversible change of fluorescence emission. At the same time, xerogel 1 formed in acetonitrile
could sensitively and reversibly respond to TFA and TEA vapour. The fluorescence emission of xerogel 1 was
changed from cyan into blue after response to TFA in one minute. When TEA was further added, the fluorescence

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emission could be fast backed from blue to its original cyan light in one minute. This soft material with remarkable
responsive ability of volatile acid and organic amine vapor provides its potential application in a variety of
advanced smart materials.
Acknowledgment
The authors thanks for the financial support by the National Natural Science Foundation of China (U1704164,
21401159 and 21501031), Institute for Conservation and Utilization of Agroꢀbioresources in Dabie Mountains,
Funding scheme for the young backbone teachers of higher education institutions in Henan Province
(2015GGJSꢀ141), the Science & Technology Innovation Talents in Universities of Henan Province (No.
17HASTIT005) and the Nanhu Scholars Program for Young Scholars of XYNU.
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Graphical abstract: