Rapid and Selective Detection of Cyanide Anion by Enhanced Fluorescent Emission and Colorimetric Color Changes at Micromole Levels in Aqueous Medium

Article abstract of DOI:10.1002/jhet.3113

One main source of cyanide (CN^?) exposure for mammals is through the plant consumption; thus, the sensitive and selective cyanide detection in plant tissue is a significant and urgent work. Here, a simple sensor N′-(2,4-dihydroxybenzylidene)naphtha[2,1-b]furan-2-carbohydrazide (Q1-3) was designed and synthesized for selective and sensitive dual-channel detection of cyanide in aqueous medium (DMSO/H₂O, 1:9, v/v). Acylhydrazone and phenolic hydroxyl groups on Q1-3 are the recognition sites, and naphthofuran group is the signal report group. The intramolecular charge transfer between the benzene group and naphthofuran group was impeded because of the electron-withdrawing groups (hydroxyl) on sensor Q1-3. Interestingly, the sensor Q1-3 exhibited an intramolecular charge transfer absorption band at 400?nm and emission band at 500?nm, respectively, directly realizing an “OFF–ON” response after the deprotonation process induced by cyanide anions in aqueous medium (DMSO/H₂O, 1:9, v/v). Notably, this sensor was successfully applied to detect cyanide anions in food samples, which proves a very simple and selective platform for on-site monitoring of cyanide in agriculture samples. In addition, the test strips and silica gel plates based on Q1-3 were also fabricated, which could act as test kits and silica gel plates for convenient and efficient detection of cyanide anions.

Full text of DOI:10.1002/jhet.3113

Month 2018 Rapid and Selective Detection of Cyanide Anion by Enhanced Fluorescent
Emission and Colorimetric Color Changes at Micromole Levels in
Aqueous Medium
*
Wen-Juan Qu, Wen-Ting Li, Hai-Li Zhang, Tai-Bao Wei, Qi Lin, Hong Yao, and You-Ming Zhang
Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Key Laboratory of
Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University,
Lanzhou, Gansu 730070, People’s Republic of China
*
E-mail: zhangnwnu@126.com
Received November 2, 2017
DOI 10.1002/jhet.3113
Published online 00 Month 2018 in Wiley Online Library (wileyonlinelibrary.com).
One main source of cyanide (CNꢀ) exposure for mammals is through the plant consumption; thus, the
sensitive and selective cyanide detection in plant tissue is a significant and urgent work. Here, a simple
sensor N0-(2,4-dihydroxybenzylidene)naphtha[2,1-b]furan-2-carbohydrazide (Q1-3) was designed and
synthesized for selective and sensitive dual-channel detection of cyanide in aqueous medium (DMSO/
H2O, 1:9, v/v). Acylhydrazone and phenolic hydroxyl groups on Q1-3 are the recognition sites, and
naphthofuran group is the signal report group. The intramolecular charge transfer between the benzene group
and naphthofuran group was impeded because of the electron-withdrawing groups (hydroxyl) on sensor
Q1-3. Interestingly, the sensor Q1-3 exhibited an intramolecular charge transfer absorption band at
400 nm and emission band at 500 nm, respectively, directly realizing an “OFF–ON” response after the
deprotonation process induced by cyanide anions in aqueous medium (DMSO/H2O, 1:9, v/v). Notably, this
sensor was successfully applied to detect cyanide anions in food samples, which proves a very simple and
selective platform for on-site monitoring of cyanide in agriculture samples. In addition, the test strips and
silica gel plates based on Q1-3 were also fabricated, which could act as test kits and silica gel plates for
convenient and efficient detection of cyanide anions.
J. Heterocyclic Chem., 00, 00 (2018).
INTRODUCTION
drinking [13]. Several analytical methods such as
voltammetry, potentiometry, and chromatography have
been used for cyanide detection [14–16]. These methods
can successfully detect cyanide anions at very low levels
(< 0.1 μM) but need tedious sample pretreatment or
expensive instrumentation [17]. Whereas chemical
sensors provide another approach, which is simple,
inexpensive, and rapid in real-time monitoring of cyanide
anions [18–23]. The sensing process is often accompanied
by changes in absorption or fluorescence spectra that can
be precisely monitored and sometimes detected by the
naked eyes [24–34]. Although various fluorescence probes
have been reported for cyanide anions, the detection of
endogenous biological cyanide in plant tissue remains to
be explored because of the high background signal and
large thickness of plant tissue that hamper the effective
application of traditional one-photo excitation. Among
Recognition of trace amounts of cyanide in biological
and environmental samples by simple and sensitive
methods is an area of immense interest due to the extreme
toxicity of cyanide at low concentrations [1–8]. The
toxicity of cyanide to mammals is mainly derived from its
propensity to bind with the iron in cytochrome oxidase,
thus inducing the inhibition of mitochondrial electron
chain transport and change of the cellular redox state
[9,10]. One main source of cyanide exposure for
mammals is through the consumption of certain foods and
plants. Therefore, it is significant to monitor cyanide in
plant tissues [11,12]. It is well known that 0.5–3.5 mg/kg
of body weight is lethal for humans. According to the
World Health Organization, water having cyanide
concentrations lower than 1.9 μM are acceptable for
© 2018 Wiley Periodicals, Inc.

W.-J. Qu, W.-T. Li, H.-L. Zhang, T.-B. Wei, Q. Lin, H. Yao, and Y.-M. Zhang
Vol 000
various types of sensors reported so far, only few of them
can detect cyanide anions in high water-content systems.
In order to solve these problems about cyanide anion
were recorded on a Shimadzu UV-2550 spectrometer.
Photoluminescence spectra were performed on
a
Shimadzu RF-5301 fluorescence spectrophotometer.
Melting points were measured on an X-4 digital melting
point apparatus. The infrared spectra were performed
on a Digilab FTS-3000 Fourier transform infrared
spectrophotometer.
detection, we designed and synthesized
a simple
chemosensor Q1-3, which can selectivity and sensitivity
dual-channel detect cyanide anions in aqueous medium
(DMSO/H2O, 1:9, v/v). The intramolecular charge
transfer (ICT) between the benzene group and
naphthofuran group was impeded because of the electron-
withdrawing groups (hydroxyl) on sensor Q1-3. The
sensor Q1-3 exhibited an ICT absorption band at 400 nm
and emission band at 500 nm, respectively, directly
realizing an “OFF–ON” response after the deprotonation
process induced by cyanide anions in aqueous medium
(DMSO/H2O, 1:9, v/v). There is an obvious color change
from colorless to yellow in visible light and a bright
yellow green fluorescent, which can be seen by naked
eyes under the UV lamp (365 nm) after the addition of
cyanide anions to the solution of Q1-3. Notably, this
sensor was successfully applied to detect cyanide in food
samples, which proves a very simple and selective
platform for on-site monitoring of cyanide in agriculture
samples. In addition, the test strips and silica gel plates
based on Q1-3 were fabricated, which could act as
convenient and efficient cyanide test kits and silica
gel plates.
Synthesis of sensor molecule Q1-3.
Compound Q1-3
can be readily prepared by a simple and low-cost amide
reaction between naphtha[2,1-b]furan-2-carbohydrazide
and 2,5-dihydroxybenzaldehyde (Scheme 1). 2-Hydroxy-
1-naphthaldehyde (0.86 g, 5 mmol) and K2CO3 (1.38 g,
10 mmol) were mixed in 20 mL dimethylformamide
(DMF), ethyl chloroacetate (0.72 g, 6 mmol) and KI
(0.09 g, 0.6 mmol) were mixed in 10 mL DMF and
stirred at room temperature for 30 min, and then the latter
slowly dripped into the former. The solution was stirred
for 4 h at 90°C and stirred continuously after the
temperature was increased to 120°C. After cooling to
room temperature, the solution was poured into 200 mL
distilled water, and the white precipitate was filtered,
washed three times with hot absolute ethanol, and then
obtained compound 1. Next, compound 1 (1.14 g,
5 mmol) and hydrazine hydrate (0.50 g, 10 mmol) were
mixed in 30 mL EtOH; the solution was stirred under
reflux for 24 h at 85°C. After cooling to room
temperature, the yellow precipitate was filtered, washed
three times with hot absolute ethanol, and then obtained
EXPERIMENTAL
compound
2.
Naphtha[2,1-b]furan-2-carbohydrazide
(0.45 g, 2 mmol), 2,5-dihydroxybenzaldehyde (0.35 g,
2.5 mmol), and 2.5 mL glacial acetic acid (AcOH) were
mixed in hot EtOH (30 mL). The solution was stirred
under reflux for 6 h. After cooling to room temperature,
the yellow precipitate was filtered, washed three times
with hot absolute EtOH, and then recrystallized with
EtOH/DMF to give a yellow powder product Q1-3
(1.45 mmol) in 72.3% (mp >300°C). IR: (KBr, cmꢀ1) ν:
3244 (acylhydrazone –NH), 2989 (phenol –OH), 1640
(C═O), 1595 (C═C). 1H-NMR (DMSO-d6, 600 MHz)
Materials and physical methods. Fresh double-distilled
water was used throughout the experiments. All other
reagents and solvents were commercially available at
analytical grade and were used without further
purification. 1H-NMR and 13C-NMR spectra were
recorded on an Agilent DD2 at 600-MHz spectra. 1H
chemical shifts are reported in ppm downfield from
tetramethylsilane (δ scale) with the solvent resonances as
internal standards. Ultraviolet–visible (UV–vis) spectra
Scheme 1. Synthesis of the sensor molecule Q1-3.
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Rapid and Selective Detection of Cyanide Anion by Enhanced Fluorescent Emission
and Colorimetric Color Changes at Micromole Levels in Aqueous Medium
δ 12.35/ppm (s, 1H, phenol –OH on ortho-position –
OH), δ 10.02/ppm (s, 1H, phenol –OH on para-position –
OH), δ 11.36/ppm (s, 1H, imide –NH), δ 7.35–8.63/ppm
(m, 9H, ArH), δ 6.35–6.40/ppm (m, 3H, PrH). 13C-NMR
(DMSO-d6, 150 MHz) δ/ppm 161.36, 159.94, 154.55,
152.86, 150.11, 147.76, 131.71, 130.56,129.31, 128.97,
127.92, 127.80, 125.93, 124.16, 123.12, 112.95, 111.04,
110.87, 108.27, 103.11. Electrospray ionization mass
spectrometry calcd for C20H14N2O4 + H+ 347.16;
found 346.10.
General procedure for ultraviolet–visible experiments.
All the UV–vis experiments were carried out in
DMSO/H2O (1:9, v/v) solution on a Shimadzu UV-2550
spectrometer. Any changes in the UV–vis spectra of the
synthesized compound were recorded on addition of
tetrabutylammonium salts while keeping the ligand
concentration constant (2.0 × 10ꢀ5 M) in all experiments.
Tetrabutylammonium salt (1.0 × 10ꢀ3 M) of anions (Fꢀ,
Clꢀ, Brꢀ, Iꢀ, AcOꢀ, H2PO4ꢀ, HSO4ꢀ, and ClOꢀ4 ) and
sodium salt (1.0 × 10ꢀ3 M) of anions (CNꢀ and SCNꢀ)
were used for the UV–vis experiments.
1.2
1.0
0.8
0.6
0.4
0.2
0.0
300
400
500
600
Wavelength (nm)
Figure 1. Absorbance spectra of compound Q1-3 (20 μM) in DMSO/
H2O (1:9, v/v) in the presence of cyanide and other anions (50 equiv). In-
set: photograph showing the change in color of the solution of Q1-3 in
DMSO/H2O (1:9, v/v, 20 μM) after addition of cyanide and other anions
at room temperature. [Color figure can be viewed at wileyonlinelibrary.
com].
region, the changes could be observed by naked eyes. The
colorless solution of sensor Q1-3 turned to yellow in the
presence of cyanide. In contrast, other anions (especially
Fꢀ, AcOꢀ, H2PO4ꢀ, and SCNꢀ) did not induce any
spectral and color changes.
General procedure for fluorescence spectra experiments.
All the fluorescence spectroscopy was carried out in
DMSO/H2O (1:9, v/v) solution on a Shimadzu RF-5301
spectrometer. Any changes in the fluorescence spectra of
the synthesized compound were recorded on addition of
tetrabutylammonium salts while keeping the ligand
concentration constant (2.0 × 10ꢀ5 M) in all experiments.
Tetrabutylammonium salt (1.0 × 10ꢀ3 M) of anions (Fꢀ,
Clꢀ, Brꢀ, Iꢀ, AcOꢀ, H2PO4ꢀ, HSO4ꢀ, and ClOꢀ4 ) and
sodium salt (1.0 × 10ꢀ3 M) of anions (CNꢀ and SCNꢀ)
were used for the fluorescence experiments.
General procedure for H-NMR experiments. For H-
NMR titrations, the solution of Q1-3 was prepared in
DMSO-d6 and the appropriate concentrated solution of
guest was prepared in deuterium water. Aliquots of the
two solutions were mixed directly in NMR tubes.
On the other hand, sensor Q1-3 represented weak
fluorescence emission in the solution, because of
the efficient electron withdrawing of phenolic
hydroxyl groups. However, a prominent fluorescence
enhancement at 500 nm appeared after the addition of
cyanide to the solution of Q1-3. Meanwhile, other anions
caused no significant influence about the fluorescent
spectra of sensor Q1-3, which could not be detected by
naked eyes under the UV lamp. According to these
results, it indicated that sensor Q1-3 could recognize
cyanide anions selectively through colorimetric and
fluorimetric dual channels in real time. In addition, no
significant changes were observed after the addition of
other anions (Fig. 2).
1
1
RESULTS AND DISCUSSION
In order to further investigate the practical applicability
of Q1-3 as a cyanide sensor, we carried out competitive
experiments in the presence of 50 equiv of cyanide
anions and 50 equiv of other anions in the solution of
Q1-3. No significant variation of the absorption spectra
and fluorescence intensity was observed by the
subsequent addition of competing anions, which indicated
that Q1-3 has specific selectivity to cyanide anions (Fig. 3).
The absorption and fluorescence titration experiments of
sensor Q1-3 were carried out to explore the interaction
between sensor Q1-3 and cyanide anions. As showed in
Figure 4, the variation in the absorption spectrum caused
by the gradual addition of cyanide carried out a red shift.
Upon the addition of 0–6 equiv of cyanide to the solution
To evaluate the real-time detection ability of sensor
Q1-3 towards various anions (such as Fꢀ, Clꢀ, Brꢀ, Iꢀ,
AcOꢀ, H2POꢀ4 , HSOꢀ4 , ClOꢀ4 , SCNꢀ, and CNꢀ), changes
in the absorption and fluorescence spectra were measured
immediately upon adding various anions to the solutions
of sensor Q1-3.
As illustrated in Figure 1, sensor Q1-3 exhibited a
maximum absorption band at 335 nm. The addition of
cyanide led to significant decrease of this band
accompanied with the emergence of three new absorption
bands at 400, 418, and 442 nm, respectively, while other
anions caused no influence in the absorption spectra.
Owing to the appearance of the new band in the visible
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W.-J. Qu, W.-T. Li, H.-L. Zhang, T.-B. Wei, Q. Lin, H. Yao, and Y.-M. Zhang
Vol 000
1.0
0.8
800
600
400
200
0
1
0.6
0.4
0.2
0.0
-1
0
1
2
3
4
5
6
7
8
Equivalents
0
300
500
600
700
400
500
Wavelength (nm)
Wavelength (nm)
Figure 2. Fluorescent spectra of compound Q1-3 (20 μM) in DMSO/H2O
(1:9, v/v) in the presence of cyanide and other anions (50 equiv.). Inset:
photograph showing the change in color of the solution of Q1-3 in
DMSO/H2O (1:9, v/v, 20 μM) after addition of cyanide and other anions
at room temperature. [Color figure can be viewed at wileyonlinelibrary.
com].
Figure 4. Absorption spectrum of Q1-3 (20 μM) in the presence of differ-
ent concentration of cyanide in DMSO/H2O (1:9, v/v) solutions at room
temperature. Inset: A plot of absorbance intensity depending on the con-
centration of cyanide at 418 nm. [Color figure can be viewed at
wileyonlinelibrary.com].
of Q1-3, the maximum absorption band of Q1-3 at 335 nm
decreased gradually, at the same time, three new absorption
bands rapidly appeared at 400, 418, and 442 nm,
respectively. The absorption reached maxima after the
addition of 6.0 equiv of cyanide anions to the solution of
Q1-3. The appearance of these three new absorption
bands indicated that the intermolecular hydrogen bonds
of N–H and O–H were broken by the deprotonation
process induced by cyanide anions.
1.0
a
Q1-3
Q1-3 with CN
Q1-3 with other anions
Q1-3 with CN and other anions
-
0.8
-
0.6
0.4
0.2
0.0
As depicted in Figure 5, the fluorescent peak at 500 nm
increased progressively upon the addition of increasing
amounts of cyanide anions. More importantly, it was
performed with
a
78-fold intensity enhancement
compared to Q1-3 when the concentration of cyanide
-
-
-
-
I
-
-
-
Q1-3
-
ClO4 SCN
-
-
CN
F
Br
Cl
AcO
H2PO4
HSO4
800
800
700
600
500
400
300
200
100
0
700
b
Q1-3
Q1-3 with CN
Q1-3 with other anions
600
500
400
300
-
600
-
200
Q1-3 with CN and other anions
100
0
0
1
2
3
4
5
6
Equivalents
400
200
0
500
600
700
-
-
-
-
I
-
-
-
Q1-3
-
ClO4 SCN
-
-
CN
F
Br
Cl
AcO
H2PO4
HSO4
Wavelength (nm)
Figure 3. (a) Absorbance data at 400 nm and (b) fluorescence emission
data for 1:50 mixture of Q1-3 (20 μM) and different
tetrabutylammonium salts of anions, in DMSO/H2O (1:9, v/v) solutions
at room temperature (excitation wavelength = 400 nm). [Color figure
can be viewed at wileyonlinelibrary.com].
Figure 5. Fluorescent spectrum of Q1-3 (20 μM) in the presence of dif-
ferent concentration of cyanide in DMSO/H2O (1:9, v/v) solutions at room
temperature. Inset: A plot of fluorescent intensity depending on the con-
centration of cyanide at 500 nm (excitation wavelength = 400 nm).
[Color figure can be viewed at wileyonlinelibrary.com].
a
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Rapid and Selective Detection of Cyanide Anion by Enhanced Fluorescent Emission
and Colorimetric Color Changes at Micromole Levels in Aqueous Medium
reached to 4 equiv. Furthermore, the lightless solution of
Q1-3 showed a bright yellow green fluorescent emission
in the presence of cyanide anions under an available UV
lamp (365 nm). On the basis of these results, it is
hypothesized that fluorescent emission change was
contributed by the deprotonation of Q1-3 induced by the
cyanide anions. The detection limits of Q1-3 towards
cyanide, obtained according to spectrophotometric
titration and fluorescence titration on the basis of 3σ/m,
were 3.6893 × 10ꢀ10 and 8.0769 × 10ꢀ7 M, respectively,
as shown in Figures S1 and S2.
properties, the effect of various pH on the emission
intensity of Q1-3 in DMSO/H2O (1:9, v/v) HEPES
buffered solution was also studied. As shown in Figure
S3, the Q1-3–CNꢀ showed significant fluorescence
response in the range of pH 4–8. Meanwhile, with the
increasing of pH, the receptor’s fluorescent gradually
increased. These results indicate that Q1-3 can detect
CNꢀ in a range of pH from 4 to 8. Besides, we also
detected the response of Q1-3 towards different anions in
DMSO/H2O (1:9, v/v, pH 7.0) HEPES buffered solution.
The result indicated that Q1-3 can selectivity detect CNꢀ
in DMSO/H2O (1:9, v/v, pH 7.0) HEPES buffered
solution (Fig. S4).
Because the pH value affects the charge distribution of
receptor Q1-3 and may change its inherent fluorescence
We further monitored the IR spectra and 1H-NMR
titration to investigate the reaction processes of the probe.
IR spectrum of Q1-3 shows two vibration band at 2989
and 3244 cmꢀ1, which can be assigned to stretching
vibrational absorption peaks of –OH and –NH groups in
the Q1-3 molecule, respectively. The vibration band at
1608 cmꢀ1 was attributed to the vibration of –CH═N.
However, when Q1-3 reacted with CNꢀ, the stretching
vibration absorption peaks of naphthol –OH and –NH
group disappeared at 2989 cmꢀ1 and 3244 cmꢀ1, which
70
Q1-3
-
Q1-3 with CN
60
50
40
30
3244
-NH
2989
-OH
indicated that Q1-3 lost the
H
proton on the
20
10
acylhydrazone and two phenolic hydroxyl groups after
the addition of CNꢀ (Fig. 6).
The results of 1H-NMR titration experiments also
support this presumption. As shown in Figure 7, after
adding 0.1 equiv of CNꢀ, the singles of phenol –OH on
ortho-position and para-position and imide –NH– peak at
4000 3500 3000 2500 2000 1500 1000
Wavelength (cm-1)
500
Figure 6. IR spectra of sensor Q1-3 and after adding cyanide anions in
KBr disks. [Color figure can be viewed at wileyonlinelibrary.com].
Figure 7. Partial 1H NMR spectra of Q1-3 (DMSO-d6) and in the presence of varying amounts of cyanide anions (1 M, D2O). [Color figure can be viewed
at wileyonlinelibrary.com].
Journal of Heterocyclic Chemistry
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W.-J. Qu, W.-T. Li, H.-L. Zhang, T.-B. Wei, Q. Lin, H. Yao, and Y.-M. Zhang
Vol 000
12.35, 10.02, and 11.36 ppm decreased and gradually
disappeared because of the deprotonation of sensor Q1-3.
At the same time, the other peaks have an obvious up
field shift upon addition of CNꢀ, indicating that CNꢀ
could take the H protons away via deprotonating of the
phenol –OH on ortho-position and para-position and
imide –NH– moiety of Q1-3, which enhanced
intramolecular electron cloud density and induced the
ICT process between the benzene group and
naphthofuran group of Q1-3.
Therefore, based on the analysis of UV–vis spectra,
fluorescence spectra, and IR and 1H-NMR spectra, we
proposed a possible mechanism for the interaction
between sensor Q1-3 and cyanide anions in the optical
detection process (Fig. 8). Cyanide could take the H
proton away via deprotonating in the phenol –OH on
ortho-position and para-position and imide –NH–
moiety of Q1-3, which enhanced intramolecular
electron cloud density and induced the ICT process
between the benzene group and naphthofuran group of
Q1-3, accompanied with absorption and fluorescence
changes.
Furthermore, in order to further investigate the practical
utilities of probe in our lives, we used the sensor to detect
the CNꢀ in bitter seeds and sprouting potatoes. Firstly,
100 g of bitter seeds was crushed and pulverized. Then
the mixture must be introduced into a flask. Along with
this, we added 300 mL water and 0.5 g NaOH, and the
obtained mixture should be vigorously stirred for 15 min.
After that, the mixture was filtered so as to obtain the
cyanide-containing solution (BSCS). And we also chose
the sprouting potatoes to implement the following
experiment. The sprouting potato (100 g) was first
mashed before being soaked in water (200 mL) for
2 days until the extract became turbid. The mixture was
filtered, and the filtrate was eluted with 125 mM NaOH
solution (100 mL) to obtain the cyanide-containing
solution (SPCS). As shown in Figure 9(b), upon the
addition of Q1-3 to the two different samples solutions of
cyanide anions, the fluorescence intensity of sensor Q1-3
increased rapidly. The color changes from dim blue to
blue-green could be distinguished by the naked eyes
under the UV lamp (365 nm) as shown in Figure 9(a).
These results showed that we can successfully use the
sensor Q1-3 to detect the cyanide anions in food samples
in our daily life.
For convenient use in an on-site visual screening
analysis, paper-based sensors and silica gel plates test
kits were prepared for visual detection of cyanide. A
series of Q1-3 (0.1 M) DMSO/H2O (1:9, v/v) solutions
were carefully dropped onto filter paper strips and then
dried at room temperature. The test strips containing
Q1-3 were utilized to sense cyanide and other anions.
As shown in Figure 10, when cyanide (0.01 M) and
the other anions (0.01 M) were added on the test kits,
respectively, the obvious color changes were observed
only with cyanide solution in visible light and under
the 365 nm UV lamp. And potentially competitive
anions exerted no influence on the detection of cyanide
by the test strips. And potentially competitive anions
exerted no influence on the detection of cyanide by the
test strips.
Figure 8. Proposed reaction mechanism of sensor Q1-3 with NaCN. ICT, intramolecular charge transfer. [Color figure can be viewed at
wileyonlinelibrary.com].
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Month 2018
Rapid and Selective Detection of Cyanide Anion by Enhanced Fluorescent Emission
and Colorimetric Color Changes at Micromole Levels in Aqueous Medium
800
sprouting potatoes
diluted bitter seeds
Q1-3
600
400
200
0
500
600
700
Wavelength (nm)
Figure 9. (a) Response photographs of Q1-3 (20 μM) in diluted bitter seeds and sprouting potatoes filter. (b) Fluorescence spectral response of Q1-3
(20 μM) in diluted bitter seeds and sprouting potatoes filter. [Color figure can be viewed at wileyonlinelibrary.com].
Figure 10. Photographs of Q1-3 and the response of cyanide on test papers in visible light and under irradiation at 365 nm. [Color figure can be viewed at
wileyonlinelibrary.com].
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W.-J. Qu, W.-T. Li, H.-L. Zhang, T.-B. Wei, Q. Lin, H. Yao, and Y.-M. Zhang
Vol 000
Figure 11. Photos of the silica gel plates utilized to sense cyanide in aqueous solution in visible light and under irradiation at 365 nm by a UV lamp.
[Color figure can be viewed at wileyonlinelibrary.com].
Figure 12. Above: photographs of Q1-3 in DMSO/H2O (1:9, v/v) solutions after immersion with different concentration of cyanide and only Q1-3 in
visible light. Below: photographs of Q1-3 in in DMSO/H2O (1:9, v/v) solutions after immersion with different concentration of cyanide and only
Q1-3 under irradiation at 365 nm. [Color figure can be viewed at wileyonlinelibrary.com].
In addition, we also prepared silica gel plates test kits by
silica gel plates into DMSO/H2O (1:9, v/v) solutions of
Q1-3 (0.1 M) and then drying in air. For instance, as
shown in Fig. 11 when we dipped on the silica gel plate,
which contains Q1-3 by a brush containing the aqueous
solution of cyanide, a pale yellow mark can be observed
in visible light, and a yellow green fluorescent image
appeared under the 365-nm UV lamp.
Furthermore, in order to conform the naked-eye
detection ability of Q1-3 in aqueous solution, we also
examined the naked-eye detection limits of Q1-3. As
shown in Figure 12, we prepared a series of solutions,
which containing different concentrations of cyanide. The
naked-eye detection limits of Q1-3 are 1 × 10ꢀ5 M in
visible light and 1 × 10ꢀ5 M under the UV lamp
(365 nm). Therefore, the probe could conveniently detect
cyanide in solutions by naked eyes at very low
concentrations.
CONCLUSION
In conclusion, we designed and synthesized an ICT-
based sensor Q1-3 for rapid response and superb
selective detection of cyanide anions in aqueous solutions
DMSO/H2O (1:9, v/v). The sensor demonstrated
advantages for cyanide anion detection such as dual-
channel and turn-on fluorescent emission, low detection
limits both in UV–vis absorption spectrum and
fluorescent emission spectrum in DMSO/H2O (1:9, v/v)
solutions, and the successful application in test kits, silica
gel plates, and food samples. It is also noteworthy that
the choice of the sensor Q1-3 allows rapid detection of
cyanide in terms of real time, as the time response
(within 3 s) here is faster compared to that of the reported
systems. This sensor allows a simple and effective way
for on-site visual detection of cyanide anions in natural
environment.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2018
Rapid and Selective Detection of Cyanide Anion by Enhanced Fluorescent Emission
and Colorimetric Color Changes at Micromole Levels in Aqueous Medium
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Acknowledgments. This work was supported by the National
Natural Science Foundation of China (Nos. 21661028,
21662031, and 21574104), the Program for Changjiang
Scholars and Innovative Research Team in University of
Ministry of Education of China (IRT 15R56).
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SUPPORTING INFORMATION
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet