A simple but sensitive and efficient fluorescent probe for “turn-on” sensing of ClO?

Article abstract of DOI:10.1016/j.poly.2020.114563

A simple but sensitive and efficient fluorescent probe YXF for “turn-on” detecting ClO^? had been developed. For compound YXF, the benzothiazole unit was the efficient fluorophore, and the C[dbnd]N unit was the recognition site for ClO^?. It could detect ClO^? with a high selectivity and sensitivity over other 29 kinds of common analytes including some reactive oxygen molecules. After addition of 30 equiv. NaClO to the solution of YXF, the fluorescent intensity at 452 nm enhanced with an approximately 37-fold within seconds. The fluorescence intensity of the reaction between YXF and NaClO showed a good linearity in the NaClO concentration range of 1–180 μM and YXF had a low detection limit of 1.8 × 10^?8 M. In addition, NaClO-promoted oxidation cleavage of C[dbnd]N unit of probe YXF was verified by HR-MS and NMR spectrometry analysis. Moreover, probe YXF could be successfully applied for detection of ClO^? concentration in several tap water and 84 disinfectant samples.

Full text of DOI:10.1016/j.poly.2020.114563

Journal Pre-proofs
A simple but sensitive and efficient fluorescent probe for “turn-on” sensing of
ClO-
Xiaofeng Yang, Wendi Shi, Xiaoling Dong, Chuanyang Cui, Xin Huang, Xue
Wang, Hangxin Xie, Yexin Li, Mei Yan, Yu Cui, Guoxin Sun
PII:
S0277-5387(20)30220-5
DOI:
Reference:
https://doi.org/10.1016/j.poly.2020.114563
POLY 114563
To appear in:
Polyhedron
Received Date:
Revised Date:
Accepted Date:
22 January 2020
10 April 2020
11 April 2020
Please cite this article as: X. Yang, W. Shi, X. Dong, C. Cui, X. Huang, X. Wang, H. Xie, Y. Li, M. Yan, Y. Cui,
G. Sun, A simple but sensitive and efficient fluorescent probe for “turn-on” sensing of ClO-, Polyhedron (2020),
doi: https://doi.org/10.1016/j.poly.2020.114563
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A simple but sensitive and efficient fluorescent probe for “turn-on” sensing of
ClO-
Xiaofeng Yanga,*, Wendi Shia, Xiaoling Donga, Chuanyang Cuia, Xin Huanga, Xue Wanga,
Hangxin Xiea, Yexin Lia, Mei Yana, Yu Cuia, and Guoxin Suna
a School of Chemistry and Chemical Engineering, University of Jinan, No. 336, West Road of Nan Xinzhuang,
Jinan 250022, Shandong, China
*Corresponding authors at: E–mail: chm_yangxf@ujn.edu.cn
1

Abstract
A simple but sensitive and efficient fluorescent probe YXF for “turn-on” detecting ClO- had been developed.
For compound YXF, the benzothilazole unit was the efficient fluorophore, and the C=N unit was the
recognition site for ClO-. It could detect ClO- with a high selectivity and sensitivity over other 29 kinds of
common analytes including some reactive oxygen molecules. After addition of 30 equiv. NaClO to the
solution of YXF, the fluorescent intensity at 452 nm enhanced with an approximately 37-fold within seconds.
The fluorescence intensity of the reaction between YXF and NaClO showed a good linearity in the NaClO
concentration range of 1-180 μM and YXF had a low detection limit of 1.8 × 10-8 M. In addition,
NaClO-promoted oxidation cleavage of C=N unit of probe YXF was verified by HR-MS and NMR
spectrometry analysis. Moreover, probe YXF could be successfully applied for detection of ClO- concentration
in several tap water and 84 disinfectant samples.
Keywords: ClO-; “turn-on”; fluorescent probe; benzothilazole
2

1. Introduction
Hypochlorous acid (HClO) is a weak acid with strong oxidation, and it can be partially ionized as hypochlorite
(ClO-) and H+ in aqueous solution. Its sodium/calcium salts are widely used as bleach, fungicide and
disinfectant [1]. In life, tap water is commonly used chlorine gas (adding about 0. 0029 g chlorine gas into 1 L
water can generate hypochlorous acid) to sterilize. Hypochlorous acid is one of the highly reactive oxygen
species (ROS), which is produced in the normal oxygen metabolism of organisms and plays an important role
in various physiological and pathological processes [2-6]. In the biological environment, the normal
concentration of hypochlorous acid is beneficial to human body and is necessary to maintain the normal
function of living cells [7]. However, excessive or uncontrolled hypochlorous acid can cause tissue damage
and lead to cardiovascular disease, lung damage, atherosclerosis, osteoarthritis and cancer [8-10]. Therefore,
microdetection of HClO/ClO- is very important and significant.
Due to its high sensitivity, low detection limit, simplicity, and especially suitable for real-time and online
analysis, fluorescent probes are favored by scientists and have been developed in large quantities from only the
literatures review in the past five years [11-24]. It is well known that HClO is a strong oxidizing reagent and it
can selectively oxidize some special functional groups, such as oxime, C=C double bond, spiro ring of
rodamine (or fluorescein), phenylselenium (or phenyltellurium), phenothiazine, and so on. Inspired by the
special oxidation properties of HClO, several fluorescent probes for HClO/ClO- have reported [25-29]. It is
very important and significant to realize the real-time, in-situ, rapid, efficient and specific detection of
HClO/ClO-. Although some reported probes could meet the above requirements, it is necessary to develop new
HClO/ClO- probes to enrich this field.
Benzothiazole molecules are fused by thiazole and benzene ring. As small molecular compounds,
benzothilazole-based fluorescent probes have been successfully used in the detection of many substances due
to their good optical properties [30-48]. However, to the best of our knowledge, only one HClO/ClO-
fluorescent probe based on benzothiazole fluorophore had been reported [48]. It was known that C=N double
bond which was connected to an organic fluorophore could be oxidized by HOCl, resulting in the fluorescence
change [48-50]. Base on this design strategy, we designed a simple, facile synthesize benzothilazole-derived
fluorescent probe (YXF) for turn-on sensing of ClO-. Experimental results showed that compound YXF could
3

quantitatively response to ClO- with a good selectivity and sensitivity over other 29 kinds of common analytes.
In addition, it showed a rapid response within seconds and a low detection limit (1.8 × 10-8 M).
NaClO-promoted oxidation cleavage of C=N unit of probe YXF was verified by HR-MS and NMR
spectrometry analysis. Moreover, probe YXF could be successfully applied for detection of ClO- concentration
in several tap water and 84 disinfectant samples.
2. Experimental section
2.1. Materials and instruments
2-Aminothiophenol (98%), glycolic acid (97%), Dess-Martin Periodinane (97%), diaminomaleonitrile (99%)
and other chemicals for synthesis were purchased from Energy Chemical supplier. Solvents were treated with
standard methods prior to use. The water used in the whole experiment was secondary distilled water. The
NaOCl solution used in the experiment was 11% by mass. Reaction was monitored by thin-layer
1
chromatography (TLC). H NMR and 13C NMR spectra were measured in acetone-d6 with tetramethylsilane
(TMS) as the internal standard on a Bruker Avance III 400 MHz spectrometer. UV-vis absorption spectra were
recorded on a Shimadzu 3100 spectrometer. Fluorescence emission spectra were recorded on an Edinburgh
Instruments Ltd-FLS920 fluorescence spectrophotometer.
2.2. Synthesis of compound YXF
Compounds 1 and 2 were synthesized according to the reported method [51]. As illustrated in Scheme 1,
compound 2 (163 mg, 1.0 mmol) and diaminomaleonitrile (108 mg, 1.0 mmol) were completely dissolved in
10 ml of EtOH, respectively. Then, the solution of compound 2 was added dropwise into the
diaminomaleonitrile solution. After the reaction mixture was stirred with refluxing for 4 h, a yellow-green
1
solid was precipitated, collected, and washed with EtOH to afford compound YXF (164 mg, yield 65%). H
NMR (400 MHz, acetone-d6), δ H 8.54 (s, 1H), 8.12 (t, J = 6.4 Hz, 2H), 7.74 (br, 2H), 7.64-7.54 (m, 2H) ppm
(Fig. S1); 13C NMR (100 MHz, Acetone-d6), δ C 165.77, 154.19, 149.17, 135.71, 128.91, 127.14, 126.85,
124.23, 122.21, 113.21, 112.17, 103.67 ppm (Fig. S2); HR-MS: m/zcalcd for C12H8N5S+ [M+H]+: 254.0495,
found: 254.0491 (Fig. S3).
2.3. Spectroscopic experiments
4

Probe YXF 0.1265g was accurately weighed and transferred into a 5 mL volumetric flask. The probe mother
liquor with a concentration of 1 × 10-1 M was prepared with DMSO constant volume. Then accurately measure
the 50 μL probe mother liquor with a pipette into a 500 mL volumetric flask, and fix the volume with
DMSO-PBS buffer (v/v, 1:1, pH 7.4) to prepare a probe solution with a concentration of 1 × 10-5 M. The final
composition of the test solution was 10 μM in DMSO-PBS buffer (v/v, 1:1, pH 7.4) solution. The test solution
was shaken and reacted at room temperature for 10 min, followed, the UV-vis and fluorescence spectra were
determined. Fluorescence emission spectra were excited with a wavelength of 360 nm. The slit width of the
excitation and emission were 10 nm and 20 nm, respectively.
The response conditions of YXF in the absence and presence of NaClO (100 equiv.) in DMSO/0.01 M PBS
buffer (pH 7.4) solution with different water content was tested (Fig. S6). Results showed that the optimal test
condition was in DMSO-PBS buffer (v/v, 1:1, pH 7.4) solution, which was used in all following experiments.
3. Results and discussion
3.1. Synthesis and optical property of compound YXF
Scheme 1. Synthesis of compound YXF.
As shown in Scheme 1, the target compound YXF was synthesized by a simple condensation reaction of
1
benzothiazole aldehyde 2 [51] and diaminomaleonitrile, and characterized by H NMR and 13C NMR spectra
(Figs. S1-S2). The [M+H]+ peak at m/z 254.0491 (calcd: 254.0495) in the HR-MS spectrum further verified
the formation of the expected adduct (Fig. S3). Next, the optical property of compound YXF was studied. As
shown in Fig. S4A, the maximum absorption band of YXF was at about 397 nm, and a very weak fluorescence
emission peak at about 445 nm was observed under excitation of 360 nm (Fig. S4B).
3.2. Sensing behavior of compound YXF
5

Fig. 1. (A) UV-vis absorption spectra of YXF (10 μM) to various analytes (100 equiv.) in DMSO-PBS buffer
(v/v, 1:1, pH 7.4) solution at room temperature. (B) Changes in the UV-vis absorption spectra of YXF (10 μM)
upon addition of 0-100 equiv. of NaClO in DMSO-PBS buffer (v/v, 1:1, pH 7.4) solution at room temperature.
Inset: photograph showed color change upon addition of NaClO (100 equiv.). (C) Changes in the UV-vis
absorption spectra of YXF (10 μM) upon addition of 0-200 equiv. of Cu(NO3)2 in DMSO-PBS buffer (v/v, 1:1,
pH 7.4) solution at room temperature. Inset: photograph showed color change upon addition of Cu(NO3)2 (200
equiv.).
Firstly, the recognition and sensing properties of compound YXF were investigated in DMSO-PBS buffer (v/v,
1:1, pH 7.4) solution using UV-vis absorption spectra. As shown in Fig. 1A, when different kinds of analytes
(100 equiv.), such as MgSO4, Cu(NO3)2, FeCl3, CoCl2, CaCl2, ZnCl2, CrCl3, MnCl2, FeCl2, NaF, Na2SO4,
1
-
NaHCO3, NaNO2, NaNO3, Na2SO3, NaCl, Na3PO4, NaI, NaClO, Na2S, ATP, H2O2, ONOO-, O2, O2 , HO•,
GSH, Hcy and Cys, was added, NaClO not only induced an obvious blue shift but also reduced the absorbance
6

of compound YXF, whereas Cu(NO3)2 altered the absorption spectrum of compound YXF with a large red
shift, indicating that compound YXF could response to these two ions by different recognition mechanisms. A
slight change in absorbance of compound YXF was induced by addition of the rest of the other tested analytes.
Fig. 1B showed that when 0-100 equiv. NaClO was gradually added to YXF (10 μM) in DMSO-PBS buffer
(v/v, 1:1, pH 7.4) solution, the maximum absorption band at about 397 nm gradually decreased and,
concomitantly, a new band at about 307 nm gradually increased. This response process was completed within
addition of 100 equiv. of NaClO as no further changes were observed with the addition up to 200 equiv. of
NaClO. An isosbestic point at 330 nm indicated that only one stable compound was formed from the reaction
of YXF with NaClO. Meanwhile, the color of the solution changed from dark yellow to pale yellow. Fig. 1C
showed that upon stepwise addition of Cu2+ ions (0-200 equiv.), the maximum absorption band at about 397
nm of compound YXF gradually decreased and, concomitantly, a new red-shifted band at about 530 nm
gradually increased. Meanwhile, the color of the solution changed from dark yellow to red. These results
demonstrated that compound YXF was characteristic of a high selectivity toward NaClO and Cu2+ ions over
other competitive analytes and could serve as a “naked-eye” probe.
Fig. 2. (A) Fluorescence spectra of YXF (10 μM) to various analytes (30 equiv.) in DMSO-PBS buffer (v/v,
1:1, pH 7.4) solution at room temperature, λem: 360 nm. (B) The fluorescence intensity of YXF (10 μM) at 452
nm in response to NaClO (30 equiv.) in the presence of various interfering analytes (50 equiv.) in DMSO-PBS
buffer (v/v, 1:1, pH 7.4) solution at room temperature, λem: 360 nm. Interfering analytes, from 1-30: blank,
7

MgSO4, Cu(NO3)2, FeCl3, CoCl2, CaCl2, ZnCl2, CrCl3, MnCl2, FeCl2, NaF, Na2SO4, NaHCO3, NaNO2, NaNO3,
-
Na2SO3, NaCl, Na3PO4, NaI, NaClO, Na2S, ATP, H2O2, ONOO-, 1O2, O2 , HO•, GSH, Hcy and Cys.
Next, the fluorescence spectra of compound YXF (10 μM) in response to different kinds of analytes (30 equiv.)
were also observed in DMSO-PBS buffer (v/v, 1:1, pH 7.4) solution. When excited at 360 nm, the
fluorescence intensity of compound YXF was almost unchanged by addition of other analytes including Cu2+
ions, while it was significantly enhanced only after adding NaClO with the fluorescence quantum yield
increasing from 0.01 to 0.38 (Fig. 2A). This indicated that compound YXF had a well-defined fluorescence
selectivity for NaClO over Cu2+ and other analytes. As shown in Fig. 2B, the fluorescence response of YXF to
NaClO was almost no effect on all these typical analytes. Thus, NaClO could be effectively detected by YXF
in the presence of other analytes including Cu2+ ions.
3.3. Fluorimetric recognition of YXF for NaClO
Fig. 3. (A) The time course of fluorescence intensity of free probe YXF (10 μM) in the absence and presence
of 30 equiv. NaClO at 452 nm in DMSO-PBS buffer (v/v, 1:1, pH 7.4) solution, λem: 360 nm. (B) Fluorescence
response at 452 nm of free probe YXF (10 μM) in the absence and presence of 30 equiv. NaClO in
DMSO-H2O (v/v, 1:1) as a function of different pH values, λem: 360 nm.
Reaction time is an important factor to evaluate the feasibility of probe detection. First, we examined the
response time of compound YXF in the presence of NaClO. As shown in Fig. 3A, the fluorescence intensity of
compound YXF did not change with time. Once 30 equiv. NaClO was added, the fluorescence intensity of
YXF at 452 nm significantly increased immediately, indicating the fluorescence response was very fast. The
8

response signal would reach the maximum value within seconds, which was very important for real-time
detection. This was consistent with the fact that the imine group could be cut off by HClO/ClO- under a
relatively mild condition [48-50].
Next, we detected the pH-dependent fluorescence changes of free probe YXF and after addition of NaClO (Fig.
3B). The fluorescent intensity of probe YXF was very low at a pH range from 1.4 to 9.6, whereas after the
addition of 30 equiv. NaClO, the fluorescent intensity at 452 nm enhanced significantly when the pH was
greater than 4.0, and the fluorescence signal was stronger under alkaline conditions, implying that NaClO
played a key role in the response system. These results indicated that YXF could be applied to selectively
detect NaClO in the physical environment.
Fig. 4. (A) Fluorescence spectra of YXF (10 μM) upon addition of 0-30 equiv. of NaClO in DMSO-PBS
buffer (v/v, 1:1, pH 7.4) solution. Inset: photograph showed color change in fluorescence upon addition of
NaClO (30 equiv.). (B) Fluorescence intensity vs. increasing concentration of NaClO, λem: 360 nm.
Followed, fluorescence titration of YXF with increasing NaClO was performed at pH 7.4. As depicted in Fig.
4A, in the absence of NaClO, compound YXF exhibited a very weak fluorescence emission in DMSO-PBS
buffer (v/v, 1:1, pH 7.4) solution. Once upon addition of NaClO at ambient temperature, a band centered at
452 nm was formed and its fluorescence intensity remarkably increased. When 30 equiv. NaClO was added,
the fluorescence intensity of the solution reached saturation representing an approximate 37-fold fluorescent
intensity signal response, and a bright cyan fluorescence could be observed. After the linear fitting between the
9

fluorescence intensity of probe YXF at 452 nm and the concentration of NaClO, a good linear correlation over
a concentration range of 1-180 μM was obtained (Fig. 4B). The linear fitting equation was: I = 76.76799 +
27.89775 [NaClO], R = 0.99623, indicating the suitability of probe YXF for quantitative detection of NaClO.
The low limit of detection (LOD) under this condition was evaluated to be 1.8 × 10-8 M (LOD = 3σ/k, σ
represented the standard deviation of the fluorescence intensity of probe YXF at 452 nm, k represented the
slope of linear fitting equation). With regard to a simple structure, a facile synthesis, as well as a high
sensitivity and a low LOD response toward ClO-, YXF achieved a potential membership of ClO- fluorescent
probe club, which was comparable with some recently reported fluorescence probes for HClO/ClO- (Table 1).
Table 1. Comparison of some reported fluorescent probes for HClO/ClO- since the year 2018.
Probe
Reponse time
2 seconds
LOD (M)
5 × 10-8
references
OH
N
H
O
N
O
N
NO2
Org. Biomol. Chem. 16
(2018) 2074
O2N
MeO
N
O
Sensors & Actuators: B.
Chemical 273 (2018) 1532
10 seconds
100 seconds
10 seconds
1.2 × 10-7
1.7 × 10-7
3.9 × 10-8
N
B
N
F
O
N
F
NC
CN
Sensors & Actuators: B.
Chemical 287 (2019) 453
N
O
O
NC
CN
New J. Chem. 42 (2018)
5135
S
N
S
N
-
Org. Biomol. Chem. 17
(2019) 108
BF4
400 seconds
9.2 × 10-8
N
O
COOH
10

NC
CN
Sensors & Actuators: B.
Chemical 255 (2018) 963
S
N
not mentioned
2 minutes
7.2 × 10-7
O
MeO
Sensors & Actuators: B.
Chemical 263 (2018) 137
4.1 × 10-9
N
N
B
S
F
F
N
3
O
S
N
O
Anal. Methods 11 (2019)
1751
20 seconds
1.165 × 10-6
N
N
N
I-
CHO
O
16 seconds
12 seconds
7.782 × 10-8
6.114 × 10-8
N
O
Sensors & Actuators: B.
Chemical 255 (2018) 2378
CHO
N
O
O
NC
N
CN
NH2
O
N
O
OH
4 minutes
7 minutes
1.2 × 10-7
2.6 × 10-8
Sensors & Actuators: B.
Chemical 269 (2018) 180
NC
N
CN
N
O
N
O
O
N
O
OH HO
NC
NC
NH2
N
Dyes and Pigments 158
(2018) 526
OH
30 seconds
8 × 10-8
O
N
N
S
CN
CN
1.8 × 10-8
This work
N
5 seconds
H2N
3.4. Proposed response mechanism
11

Scheme 2. Proposed response mechanism for YXF with NaClO.
The sensing mechanism for YXF with NaClO was proposed in Scheme 2. As the previous reported literature
about oxidation of C=N double bond derivative from diaminomaleonitrile with HClO/ClO-, the hydrazone
group could be transformed by NaClO to give the aldehyde oxide derivative [48-50]. In order to verify the
possibility of the above recognition mechanism, the mixture of NaClO and probe YXF was tested by HR-MS
spectrometry. After reaction with 30 equiv. NaClO for 10 minutes, the mass spectral peak of the reaction
product at m/z 164.0161 corresponding to the oxidation product [2+H]+ was observed, and there was no peak
of YXF (m/z 254.0459) (Fig. S5). This result indicated that probe YXF was converted into 2 completely. The
1
sensing mechanism was further confirmed by H NMR spectrum titration analysis on the mixture of probe
YXF with NaClO in acetone-d6. As illustrated in Fig. 5, upon the addition of NaClO, the proton signal at 8.64
ppm (Ha) of probe YXF which was assigned to the –CH=N– group disappeared and, concomitantly, a new
proton signal at 10.20 appeared which was consistent with the proton signal of Hb of compound 2. In addition,
the other proton signals generated from the mixture of probe YXF with NaClO also corresponded to those of
compound 2. These data strongly supported our proposed mechanism for the manner in which NaClO reacted
with probe YXF to generate compound 2.
12

Fig. 5. Partial 1H NMR of YXF (A), compound 2 (B), and YXF + NaClO (C) in acetone-d6.
3.7. Detection of ClO- in tap water
In order to exploit its real application, the performance of probe YXF of detecting ClO- in tap water samples
was studied (Table 2). The tap water samples were used directly for determination without special treatment.
The recovery of ClO- was determined by the standard addition method through the fluorescence spectra
titration. The statistical data in the Table 2 demonstrated that the average recovery rates of ClO- in the real
water sample were about 98.5~102.1%, indicating that the prepared probe YXF-ClO could be successfully
used for the analysis and determination of ClO- in the real sample.
Table 2. Experimental results of real tap water samples recovery.
Sample Labeled (μM)
5.00
Added (μM)
Found
6.02
Recovery (%)
102.1
RSD * (%)
1.6
1
1.00
13

2
3
5.00
5.00
3.00
5.00
7.91
9.86
98.3
98.5
2.1
2.6
* Relative Standard Deviation, n=5.
3.8. Detection of ClO- level in 84 disinfectant samples
The feasibility of probe YXF for detecting ClO- in practical samples was explored. From the fluorescence
spectra titration curves (Fig. S7) and the calibration curve (Fig. 4B), the ClO- level in the purchased 84
disinfectant sample was calculated to be 1.02 M, which was within the range from 0.95 to 1.30 M of product
concentration (the effective chlorine level was 34.0-46.0 g/L). Furthermore, the calculated recovery values of
ClO- were between 94.4% and 102.9%, indicating the accuracy and scientific nature of this method. Therefore,
probe YXF could be used to detect ClO- level in 84 disinfectant samples. The corresponding calculated values
were listed in Table 3.
Table 3. Determination of ClO- level in 84 disinfectant samples.
ClO- level found
(M)
ClO- added
ClO- found
Recovery
(%)
RSD *
(%)
Sample
(mM)
(mM)
84
1.02
1.02
2.04
3.06
0.98
2.10
2.89
96.1
102.9
94.4
0.6
1.1
0.8
disinfectan
t
* Relative Standard Deviation, n=5.
4. Conclusions
In summary, a simple structure and facile synthesis new fluorescence probe, YXF for “turn-on” response to
ClO- was developed. It could detect ClO- with a high selectivity and sensitivity over other 29 kinds of common
analytes including some reactive oxygen molecules. After addition of 30 equiv. NaClO to the solution of YXF,
the fluorescence intensity at 452 nm enhanced with an approximately 37-fold within seconds and,
concomitantly, the fluorescence color from dark to bright cyan could be observed. A linear calibration curve
was obtained between the fluorescence intensity at 452 nm and the NaClO concentration range of 1-180 μM
14

indicating this probe was suitable for quantitative determination of ClO-. Furthermore, it was found that YXF
had a detection limit of 1.8 × 10-8 M. In addition, NaClO-promoted oxidation cleavage of C=N unit of probe
YXF was verified by HR-MS and NMR spectrometry analysis. Moreover, probe YXF could be successfully
applied for detection of ClO- concentration in several tap water and 84 disinfectant samples.
Conflict of interest statement
The authors have declared that no conflict of interest exists.
Acknowledgments
Financial support by the National Natural Science Foundation of China (Grants 21708013, 21675064,
51473067), the China Postdoctoral Science Foundation (Grants 2017M620288), Natural Science Foundation
of Shandong Province of China (ZR2018MB016), Young Taishan Scholars Program of Shandong Province
(TSQN20161036), and Major basic research projects of natural science foundation of Shandong province
(ZR2018ZC0230).
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in the online version, at http://
15

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Wendi Shi: Investigation, Data curation.
19

Xiaoling Dong: Investigation, Data curation.
Chuanyang Cui: Investigation, Data curation
Xin Huang: Investigation, Data curation
Xue Wang: Investigation, Data curation
Hangxin Xie: Investigation, Data curation
Yexin Li: Software, Funding acquisition.
Mei Yan: Validation, Funding acquisition.
Yu Cui: Validation.
Guoxin Sun:Writing- Reviewing and Editing.
A simple but sensitive and efficient “turn-on” benzothilazole-based fluorescent probe YXF for
ClO- detection was developed. Compared with previous fluorescent probes, the main advantages
of this probe were a rapid response time (within 5 seconds), a low detection limit (1.8 × 10-8 M),
a high selectivity and an excellent sensitivity.
Highlights
• A simple “turn-on” benzothilazole-based fluorescent probe for ClO-.
• A rapid-response time within 5 seconds for detection ClO-.
20

• A low detection limit of 1.8 × 10-8 M for ClO-.
• High selectivity and sensitivity for ClO-.
21