Ratiometric fluorescent sensor based oxazolo-phenazine derivatives for detect hypochlorite via oxidation reaction and its application in environmental samples

Article abstract of DOI:10.1016/j.dyepig.2019.107765

In this work, we designed and synthesized a ratiometric fluorescent sensor (POC) based phenazine derivative which can specifically detect hypochlorite (detection limit equals to 8.9 × 10^?7 M) in DMSO/H₂O (3:7, v/v) solution. With addition of hypochlorite to the solution of POC, hypochlorite broken π-π stacking of POC, and then oxidizes sulfur atoms in phenazine groups to sulfoxide, which resulted in the fluorescent color changed from blue to yellow. Job's plot showed that binding stoichiometry of POC with ClO^? was 2:1. In addition, POC could be used to real-time detect hypochlorite in environment samples, and the naked eyes detection limit reached up to 7 × 10^?5 M.

Full text of DOI:10.1016/j.dyepig.2019.107765

Journal Pre-proof
Ratiometric fluorescent sensor based oxazolo-phenazine derivatives for detect
hypochlorite via oxidation reaction and its application in environmental samples
You-Ming Zhang, Hu Fang, Wei Zhu, Jun-Xia He, Hong Yao, Tai-Bao Wei, Qi Lin,
Wen-Juan Qu
PII:
S0143-7208(19)31360-9
DOI:
https://doi.org/10.1016/j.dyepig.2019.107765
DYPI 107765
Reference:
To appear in: Dyes and Pigments
Received Date: 12 June 2019
Revised Date: 31 July 2019
Accepted Date: 31 July 2019
Please cite this article as: Zhang Y-M, Fang H, Zhu W, He J-X, Yao H, Wei T-B, Lin Q, Qu W-J,
Ratiometric fluorescent sensor based oxazolo-phenazine derivatives for detect hypochlorite via
oxidation reaction and its application in environmental samples, Dyes and Pigments (2019), doi: https://
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Graphical abstract
In this work, we designed and synthesized a phenazine derivative (POC) based
fluorescent sensor which could high selectivity detect hypochlorite in DMSO/H O
2
(3:7, v/v) solution.

Ratiometric fluorescent sensor based oxazolo-phenazine
derivatives for detect hypochlorite via oxidation reaction and its
application in environmental samples
a,b*
a
a
a
a
a
You-Ming Zhang ,Hu Fang , Wei Zhu , Jun-Xia He , Hong Yao , Tai-Bao Wei ,
a
a*
Qi Lin , Wen-Juan Qu
a
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. P. R. China
b
College of chemistry and Chemical Engineering, Lanzhou City University, Lanzhou, Gansu,
730070, P. R. China
Abstract
In this work, we designed and synthesized a ratiometric fluorescent sensor (POC)
based phenazine derivative which can specifically detect hypochlorite (detection limit
−
7
equals to 8.9 × 10 M) in DMSO/H O (3:7, v/v) solution. With addition of
2
hypochlorite to the solution of POC, hypochlorite broken π-π stacking of POC, and
then oxidizes sulfur atoms in phenazine groups to sulfoxide, which resulted in the
fluorescent color changed from blue to yellow. Job’s plot showed that binding
−
stoichiometry of POC with ClO was 2:1. In addition, POC could be used to
real-time detect hypochlorite in environment samples, and the naked eyes detection
−
5
limit reached up to 7 × 10 M.
*
Corresponding author
Tel: +086 9317973191; E-mail address: zhangnwnu@126.com (You-Ming Zhang)
*
Corresponding author
E-mail address: quwenjuanlz@163.com (Wen-Juan Qu)

Keywords: Phenazine derivative; hypochlorite; ratiometric fluorescent sensor; oxidation
reaction; environmental samples
1
. Introduction
It is well known that hypochlorite has strong oxidizing properties under acidic or
alkaline conditions and it could be used as bactericidal agent [1]. Nowadays,
hypochlorite has been widely used in household bleaching, disinfection of drinking
water and swimming pools. It is worth mentioning that using appropriate amount of
hypochlorite could provide us a clean environment, safe drinking water and served as
an effective antibacterial agent in life [2, 3]. However, hypochlorite is also a
double-edged sword. Residual hypochlorite in water could enter the living body
through some routes and then enriched [4], which may induce oxidative stress and
oxidative damage, even cause more serious diseases such as arthritis and
cardiovascular disease, hard atheroma, neuronal degeneration and cancer [5-11].
Hence, it is urgent needed to develop a novel method for efficiently detecting
hypochlorite in environmental samples.
Methods for detection of hypochlorite included normalized iodometric titration [12],
electrochemical analysis [13], spectrophotometry [14], chemiluminescence [15], and
colorimetric chemosensor [16]. However, these detection methods require expensive
instruments and were not easy to promote. In recent years, fluorescent sensors have
become popular [17-20]. Fluorescent sensors based on small organic molecules have
attracted wide attention of researchers because of their low cost, simple synthesis and
easy operation [21-27]. Up to now, a large number of organic fluorescent sensors have

been developed, but ratiometric fluorescence sensors which could be used to sensitive
and convenient detect hypochlorite have been rarely reported [28-34].
Phenazine and its derivatives were used as raw materials for organic synthesis and
dye intermediates widely used in daily life and work [35-40]. At the same time,
phenazine derivatives could be used as ionic ligands and hydrogen bond acceptors
because of their own structural characteristics (containing electron-deficient π system,
with the pair of electron-bearing nitrogen atoms and three fused aromatic rings). It
was also beneficial for π-π electrons to overlap each other, so a kind of compound has
considerable application prospects in supramolecular chemistry [41-46]. Therefore,
combining with our previous works [47, 48], we designed and synthesized
2
-(methylthio)oxazolo[4,5-b]phenazine (POC) as novel ratiometric fluorescent sensor
(Scheme1), which could high sensitivity and selectivity identification hypochlorite
through oxidation reaction. Adding hypochlorite to POC in the DMSO/H O (3:7, v/v)
2
solution, hypochlorite broken π-π stacking of POC, and then oxidizes sulfur atoms in
phenazine groups to sulfoxide, fluorescence color of POC solution changed from
green to yellow.
As we all know, the active ingredient of 84 disinfectant was hypochlorite. We
®
diluted the 84 disinfectant (jing bai li ) with tap water, and then added different
concentrations of 84 disinfectant to POC (20 µM) solution to observe the color
−
5
change. The naked-eyes detection limit of POC to 84 disinfectant was 7 × 10 M
under the UV lamp (365 nm). So POC could be applied to the on-site and real-time
monitoring of hypochlorite in daily-life samples.

Scheme1
2
. Experimental section
2
.1. Materials
All reagents were analytical grade, commercially and without further purification.
UV-vis spectra were recorded on a Shimadzu UV-2550. Fluorescence spectra were
1
recorded on a Shimadzu RF-5301PC. H NMR spectra were recorded on a
Mercury-400BB spectrometer at 400 MHz with DMSO-d as solvent. Chemical shifts
6
are reported in ppm downfield from tetramethylsilane (TMS, δ scale with solvent
resonances as internal standards). Mass spectra were performed on a Bruker Esquire
3
000 plus mass spectrometer (Bruker-FranzenAnalytik GmbH Bremen, Germany)
equipped with ESI interface and ion trap analyzer.
2
.2. Synthesis and characterization of sensor POC
A mixture of oxazolo[4,5-b]phenazine-2-thiol (0.253 g, 1 mmol), K CO (0,138 g,
2
3
1
mmol), KI (1.992 g, 1.2 mmol), methyl iodide (0.171 g, 1.2 mmol) and acetonitrile
(50 mL) were add to a 100 mL round-bottom flask under nitrogen atmosphere. The
reaction mixture was stirred at 80℃ for 72h. The crude product was purified by silica
gel column chromatography using petroleum ether/ethyl acetate (v/v = 50:1) as the
eluent, compound POC as yellow solid (0.234 g, yield 88%) was isolated, m.p.
1
2
2
63-265℃ H NMR (Figure S1) (400 MHz, DMSO-d ) δ 8.35 (s, 2H, ArH), 8.25 (s,
6
1
3
H, ArH), 7.96 (d, J = 3.2 Hz, 2H, ArH), 2.89 (d, J = 2.5 Hz, 3H, SCH ). C NMR
3
(
151 MHz, CDCl ), δ/ppm: 172.66, 142.83, 142.74, 141.72, 141.35, 130.18, 130.12,
3

1
29.38, 129.19, 115.15, 105.96, 14.70. ESI-MS m/z: Calcd for C H N OS [POC +
14 10 3
+
H] : 268.0545; Found 268.0542 (Figure S2).
2
.3. Preparation of solutions of ROS and anions
2
-
-
The ROS (reactive oxygen species) including NO•, •O , ONOO , H O , OH•,
2
2
–
t-BuOOH and ClO were prepared as follows: NaClO was prepared by diluting with 8%
−
2
aqueous solution, and final concentration is 1.0 × 10 M. H O was obtained by
2
2
−2
diluting with 30% aqueous solution, and final concentration is 1.0 × 10 M. Nitric
oxide radical (NO•) was generated from SNP (sodium nitrofer-ricyanide (III)
dihydrate). SNP was added to deionized water and then stirred for 1 h at room
temperature. Hydroxyl radical (OH•) was generated by the Fenton reaction. To
prepare OH• solution, FeSO was added in the presence of 50 µM of H O . With
4
2
2
deionized water, a 70% solution was diluted to prepare tert-butyl hydroperoxide
2
-
(
t-BuOOH). The superoxide radical (•O ) was generated from improved
1
,2,3-trihydroxybenzene autoxidation method, the pyrogallol solution (in 1 M HCl)
-
was thoroughly mixed with pH 7.4 Tris-HCl buffer. Peroxynitrite (ONOO ) was
prepared by the reaction of hydrogen peroxide with sodium nitrite. Sodium salt (1.0 ×
−
2
−
−
−
−
−
−
−
1
0 M) of anions (F , Cl , I , SCN , ClO , BrO , and IO ) and potassium salt (1.0
3
3
3
−
2
−
−
2−
4
3−
4−
5−
10
−
2−
3
×
10 M) of anions (Br , H PO , HPO , PO , P O , P O , HSO , SO ,
2
4
4
2
7
3
4
2−
2−
2−
3−
−
−
2
2−
4
2−
−
2−
7
SO , S O , S , N , NO , NO , C O , CO , AcO , and B O ) was prepared
4
2
3
3
2
3
4
in twice-distilled water.
Figure 1; Figure 2

3
. Results and Discussion
3
.1. Self-assembly study
At the beginning, we investigated the self-assembly procedure of POC in
DMSO-H O binary solution. As shown in Figure 1, the POC (20 µM) could dissolve
2
in DMSO solution and no fluorescence. With water content increases, the emission
intensity at 489 nm increased gradually and the green fluorescence appeared. The
emission intensity was maximized when the water content reaches 70%. Regrettably,
as the water content continues to increase, the fluorescence intensity at 489 nm
decreases gradually. According to the related reports [49-51], we speculate that POC
has π-π stacking interactions in DMSO-H O binary system (Scheme 2). Meanwhile,
2
the XRD spectra supported this proposed mechanism in Figure S4. The free sensor
POC has a peak at 2θ=23.7°, corresponding to d-spacing of 3.81Å, which indicated
that π-π stacking interactions existed in POC. Based on the above tests, we
determined that the POC could self-assemble via π-π stacking interactions in
DMSO-H O binary system.
2
3
.2. Photophysical properties of sensor POC
We carried out its UV-vis absorption experiments. As shown in Figure S5, sensor
−
POC (20 µM) with and without ClO were observed in DMSO/H O (3:7, v/v)
2
solution, the free sensor POC have a strong absorption peak at 390 nm. Interestingly,
−
when excess ClO were added to the sensor POC (20 µM) solution, the absorption
peak at 390 nm decreased and a broad shoulder peak appeared at 430 nm. Meanwhile,
the color of POC solution changed from colorless to pale yellow. In addition,

−
fluorescence spectra of sensor POC with and without ClO were observed in
DMSO/H O (3:7, v/v) solution. As shows in Figure 2, sensor POC (20 µM) exhibits a
2
strong emission peak at 489 nm, delightfully, fluorescence emission from a solution of
−
POC undergoes a 61 nm red-shift upon addition of ClO , and fluorescence color
dramatically changed from green to yellow. Subsequently, we investigated the ability
of the sensor molecule POC for detect hypochlorite in different DMSO-H O binary
2
solution. As shown in Figure S6 the sensor of POC showed good detection ability for
hypochlorite under different DMSO-H O binary solution, with the increase of water
2
content, the emission intensity at 520 nm gradually decreases. And time-dependent
variations in the fluorescence emission spectroscopes were monitored in the presence
−
of 50 equivalents of ClO , as shown in Figure S7. The kinetic study showed that the
−
reaction was completed within 18 min for ClO . What’s more, with the time extension,
the intensity ratio (F /F ) remains unchanged.
4
89 550
Figure 3
3
.3. Sensitivity studies
−
The interaction between POC and ClO was further investigated through fluorescence
titration methods by adding a standard solution of corresponding ions to a
−
5
DMSO/H O (3:7, v/v) solution of the POC (2.0×10 M). As shown in Figure 3,
2
−
Upon addition of ClO (0-122 equiv.), an isosbestic point at 520 nm was clearly
observed with increasing concentrations of hypochlorite, at the same time, the
emission intensity at 489 nm gradually decreased as well as the emission intensity at

5
50 nm increased gradually. The ratio of the fluorescence intensities at 489 and 550
−
nm (F /F ) decreases 33-fold upon addition of 122 equivalents ClO . Moreover, in
4
89 550
−
order to further determine the detection limit of the POC to ClO , the fluorescence
spectrum of the blank test was measured 20 times, and the standard deviation of the
blank measurement was calculated. The linear fitting was performed according to the
fluorescence titration curve to determine the slope (Figure S8). The detection limit
was calculated using the following equation: Detection limit = 3σ/S. The detection
−7
limit of POC to hypochlorite was 8.9 × 10 M. We have compared the POC with
−
other reported sensors. We found that the response time of POC for ClO was 18 min,
−
which was longer than other reported sensors, but the sensitivity of POC for ClO
was higher than other reported sensors.
Figure 4
3
.4. Selectivity studies
In order to investigate the selectivity of POC to ClO , we measured the
−
−
−
fluorescence intensive of POC in the presence of various analytical substrates (F , Cl ,
−
−
−
−
−
−
−
2−
3−
4
4−
7
5−
10
−
I , SCN , ClO , BrO , IO , Br , H PO , HPO , PO , P O , P O , HSO ,
3
3
3
2
4
4
2
3
4
2−
2−
2−
3
2−
3−
−
3
−
2−
4
2−
3
−
2−
7
−
SO , SO , S O , S , N , NO , NO , C O , CO , AcO , B O , ClO , and
3
4
2
2
2
4
H O ). As shown in Figure 4, after addition of hypochlorite to POC, the maximum
2
2
fluorescence emission peak of POC was red-shifted from 489 nm to 550 nm, while
other analytical substrates showed no change in maximum fluorescence emission peak.
Competition experiments also showed that other analytes had no effect on POC

detection hypochlorite. As shown in Figure 5, the ratio of intensity ratio (F /F )
4
89 550
was hardly changed by adding 50 equivalents of other analytical substrates to the
−
solution of POC-ClO . Subsequently, we measured the fluorescence intensive of
2
-
-
POC in the presence of various reactive oxygen species (including NO•, •O , ONOO ,
–
–
H O , OH•, t-BuOOH and ClO ). As shown in Figure S9 and Figure S10, Only ClO
2
2
responds to POC, competition experiments also showed that other reactive oxygen
species had no effect on POC detection hypochlorite. The above experiments showed
that POC could high selectivity detect hypochlorite.
Figure 5
3
.5. The effect of pH
To further confirm the practical applicability of POC, pH effect on the performance
−
of POC toward ClO was investigated from pH 2 to 13 in DMSO/H O (3:7, v/v)
2
HEPES buffered solution. The results were depicted in Figure S11, Figure S12 and
−
S13. In the absence of ClO , the intensity ratio of the sensor POC (F /F )
4
89 550
−
drastically reduced at pH > 11, but in the presence of ClO , the intensity ratio of the
sensor POC (F /F ) remained unchanged in a broad pH range. These results
4
89 550
−
indicated that ClO could be clearly detected by fluorescence spectral measurement
using POC in the broad pH range of 2-10.
3
.6. Stoichiometric relationship studies
−
In order to determine the stoichiometric relationship between POC and ClO , job
−
plot was obtained. The method was that keeping total concentration of POC and ClO

−
at 10.0 µM in DMSO/H O (3:7, v/v) solution, and changing the molar ratio of ClO
2
−
−
(
X ; X = [ClO ]/{[POC]+[ ClO ]}) from 0 to 1. As shown in Figure 6, the
M M
fluorescence intensity at 550 nm was plotted against molar fraction of POC sensor.
The maximum emission intensity was reached when the molar fraction was 0.3. This
−
result illuminated that binding stoichiometry of POC with ClO was 2:1. The same
1
result was obtained for the H NMR titration experiment. As shown in Figure 7, when
−
0
.5 equivalents ClO were added to POC, the signal peak at 2.89 ppm was shifted to
2
.93 ppm.
Scheme 2
3
.7. Sensing mechanism
It is well known that under certain oxidizing agents, thioether groups can be
oxidized to sulfoxide groups, sulfones groups, and even sulfonates. According to
previous reports [52, 53], we proposed a reasonable mechanism for the detection of
hypochlorite by POC in aqueous solution. As shown in scheme 2, with addition of
hypochlorite to the solution of POC, hypochlorite broken π-π stacking of POC, and
then oxidizes sulfur atoms in phenazine groups to sulfoxide. In order to further verify
1
the proposed response mechanism, we performed XRD, H NMR and mass
spectrometry measurements. The above self-assembly mechanism was confirmed by
XRD (Figure S4). The free sensor POC have a peak at 2θ=23.7°, corresponding to a
d-spacing of 3.81Å, indicating that π-π stacking interactions exists in POC. In
−
addition, compared to POC-ClO , this peak was significantly decreased. The

1
experiments showed that hypochlorite leads to π-π stacking decreased. The H NMR
titration experiment was recorded, as shown in Figure 7, with the addition of
d
hypochlorite to POC solution, H (2.89 ppm) signal peak in DMSO-d gradually
6
−
disappeared, and when 0.5 equivalent of ClO was added, a new signal peak appeared
a
b
c
at 2.93 ppm, the signals of H (8.34 ppm), H (8.24 ppm) and H (7.96 ppm) showed
downfield shifts (shifted to 8.38 ppm, 8.29 ppm, 8.02 ppm, respectively), which
indicated that with the addition of hypochlorite, the electronegativity of POC
increases, and peak of POC signal shift to downfield field. To further verify
−
rationality of sensing mechanism, we tested the reaction mixture of POC and ClO by
mass spectrometer. To our delight, Figure S14 manifests an increased molecular
weight of 16, which is equal to the molecular weight of oxygen. The above
experiments supported our proposed sensing mechanism. Hypochlorite broken π-π
stacking of POC, and then oxidizes sulfur atoms in phenazine groups to sulfoxide.
Figure 6
3
.8. POC detection of 84 disinfectant
Based on above experiment results, we further investigated the applicability of
sensor POC for detecting hypochlorite in daily life relevant samples. We prepared a
®
commercially available 84 disinfectant (jing bai li ) as analytical substrate. As shown
in Figure S15, we added different concentrations of hypochlorite disinfectant solution
−
6
to 20 µM POC DMSO/H O (3:7, v/v) solution. When concentrations reached 7 × 10
2
M, the fluorescent color of solution couldn’t change obviously. Thus the naked-eyes

−
5
detection limit of POC to hypochlorite was 7 × 10 M under the UV lamp (365 nm).
In order to investigate the practical application of sensor POC, test strips were
prepared by immersing filter papers into DMSO/H O (3:7, v/v) solution of POC (2 ×
2
−
4
1
0 M) and then drying in air. As shown in Figure S16, when 84 disinfectant and
other ions were added to the test kit, the obvious color changes was observed only
with 84 disinfectant under the UV-lamp (365 nm), and potentially competitive
analytical substrates did not affect the detection of the disinfectant solution by the test
strip. Therefore, POC provides a possibility for detecting hypochlorite disinfectants
on-site in daily life, and POC test strip could be used as an effective tool for detecting
hypochlorite in real time.
Figure 7
4
. Conclusion
In summary, a novel ratiometric fluorescent sensor for highly selective and
sensitive detection hypochlorite based on phenazine derivative was designed and
synthesized, which could be used as a fluorescent response sensor for hypochlorite in
DMSO/H O (3:7, v/v) solution. Detailed mechanism studies indicate that addition of
2
hypochlorite, hypochlorite broken π-π stacking of POC, and then oxidizes sulfur
atoms in phenazine groups to sulfoxide. The detection limit of POC to hypochlorite
−7
was as low as 8.9 × 10 M in aqueous solution. In addition, POC could detect 84
−
5
disinfectant in aqueous solution, and naked-eyes detection limit was 7 × 10 M. POC
test strips could be applied to detect hypochlorite rapidly of hypochlorite in the

disinfectant. In view of this, we designed and synthesized a phenazine
derivative-based ratiometric fluorescent sensor molecule POC, which provides a
practical method for the detection of hypochlorite in daily life samples.
Acknowledgements
This work was supported by the National Natural Science Foundation of China
(NSFC) (Nos. 21574104; 21662031; 21661028), the Natural Science Foundation of
Gansu Province (1506RJZA273) and the Program for Changjiang Scholars and
Innovative Research Team in University of Ministry of Education of China
(
IRT15R56).
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Table of Contents
Scheme 1 Structure and synthesis of the sensor POC.
Figure 1 The response fluorescence intensity POC (20 µM) with different
volumetric fractions of water (Vol%).
Figure 2 The response fluorescence intensity of POC (20 µM) were present
−
and absent ClO in DMSO/H O (3:7, v/v) solution. Inset: photograph
2
−
showing the change in fluorescence color of POC after addition of ClO (50
equiv.) in DMSO/H O (3:7, v/v) solution.
2
Figure 3 The response fluorescence intensity of POC (20 µM) were present
−
different concentration ClO in DMSO/H O (3:7, v/v) solution. Inset: The
2
ratios of emission intensities at 489 and 550 nm (F /F ) depending on the
4
89 550
−
concentration of ClO .
−
5
Figure 4 Fluorescent spectra of target compound POC (2.0 × 10 M) in
DMSO/H O (3:7, v/v, 20 µM) solution in the presence of hypochlorite and
2
other analytical substrate (50 equiv.). Inset: photograph showing the change
in color of the solution of POC in DMSO/H O (3:7, v/v, 20 µM) solution
2
after addition of hypochlorite and other analytical substrate using UV-lamp at
room temperature.
Figure 5 The intensity ratio (F /F ) for a 1:50 mixture of POC (20 µM)
4
89 550
and different analytical substrates, in DMSO/H O (3:7, v/v) solution at room
2
−
−
temperature. The order of the analytical substrate is: 1 POC, 2 ClO , 3 F , 4
−
−
−
−
−
−
2−
−
3−
4
Cl , 5 Br , 6 I , 7 ClO , 8 BrO , 9 IO , 10 HPO , 11 H PO , 12 PO ,
3
3
3
4
2
4

4−
5−
10
−
2−
3
2−
2−
3
2−
1
3 P O , 14 P O , 15 HSO , 16 SO , 17 SO , 18 S O , 19 S , 20
2
7
3
4
4
2
−
−
−
3
−
2−
2−
−
2−
SCN , 21 N , 22 NO , 23 NO , 24 C O , 25 CO , 26 AcO , 27 B O
3
2
2
4
3
4
7
and 28 H O .
2
2
−
Figure 6 Job’s plot examined between POC and ClO , indicating the 2:1
stoichiometry.
−
Scheme 2 Chemical structures and cartoon representations of POC and ClO
and the reaction mechanism in this system.
1
Figure 7 Partial H NMR spectra of POC (DMSO-d ) and in the presence of
6
varying amounts of hypochlorite.

Scheme 1 Structure and synthesis of the sensor POC.

Figure 1 The response fluorescence intensity POC (20 µM) with different
volumetric fractions of water (Vol%).
Figure 2 The response fluorescence intensity of POC (20 µM) were present
−
and absent ClO in DMSO/H O (3:7, v/v) solution. Inset: photograph
2
−
showing the change in fluorescence color of POC after addition of ClO (50
equiv.) in DMSO/H O (3:7, v/v) solution.
2

Figure 3 The response fluorescence intensity of POC (20 µM) were present
−
different concentration ClO in DMSO/H O (3:7, v/v) solution. Inset: The
2
ratios of emission intensities at 489 and 550 nm (F /F ) depending on the
4
89 550
−
concentration of ClO .

−
5
Figure 4 Fluorescent spectra of target compound POC (2.0 × 10 M) in
DMSO/H O (3:7, v/v, 20 µM) solution in the presence of hypochlorite and
2
other analytical substrate (50 equiv.). Inset: photograph showing the change
in color of the solution of POC in DMSO/H O (3:7, v/v, 20 µM) solution
2
after addition of hypochlorite and other analytical substrate using UV-lamp
(365 nm) at room temperature.

Figure 5 The intensity ratio (F /F ) for a 1:50 mixture of POC (20 µM)
4
89 550
and different analytical substrates in DMSO/H O (3:7, v/v) solution at room
2
−
−
temperature. The order of the analytical substrate is: 1 POC, 2 ClO , 3 F , 4
−
−
−
−
−
−
2−
−
3−
4
Cl , 5 Br , 6 I , 7 ClO , 8 BrO , 9 IO , 10 HPO , 11 H PO , 12 PO ,
3
3
3
4
2
4
4−
5−
10
−
2−
3
2−
2−
3
2−
1
3 P O , 14 P O , 15 HSO , 16 SO , 17 SO , 18 S O , 19 S , 20
2
7
3
4
4
2
−
−
−
3
−
2−
2−
−
2−
SCN , 21 N , 22 NO , 23 NO , 24 C O , 25 CO , 26 AcO , 27 B O
3
2
2
4
3
4
7
and 28 H O .
2
2