Iridium (III) complex-based fluorescent probe for detection of thiophenols and its application in water samples

Article abstract of DOI:10.1016/j.dyepig.2018.11.051

In consideration of the nucleophilic capacity of thiophenols, which could cleave sulfonamide bond under neutral conditions, a cyclometalated iridium(III) complex (probe 1) comprised 2,4-dinitrobenzenesulfonamide (DNBS) as the recognition unit was designed

Full text of DOI:10.1016/j.dyepig.2018.11.051

Accepted Manuscript
Iridium(III) complex-based fluorescent probe for detection of thiophenols and its
application in water samples
Haiyue Lu, Daobin Zhang, Congbin Fan, Yaqian Guo, Xiaoli Xia, Shouzhi Pu
PII:
S0143-7208(18)32375-1
https://doi.org/10.1016/j.dyepig.2018.11.051
DYPI 7195
DOI:
Reference:
To appear in: Dyes and Pigments
Received Date: 26 October 2018
Revised Date: 21 November 2018
Accepted Date: 25 November 2018
Please cite this article as: Lu H, Zhang D, Fan C, Guo Y, Xia X, Pu S, Iridium(III) complex-based
fluorescent probe for detection of thiophenols and its application in water samples, Dyes and Pigments
(2018), doi: https://doi.org/10.1016/j.dyepig.2018.11.051.
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ACCEPTED MANUSCRIPT
Iridium(III) complex-based fluorescent probe for detection
of thiophenols and its application in water samples
Haiyue Lu, Daobin Zhang*, Congbin Fan, Yaqian Guo, Xiaoli Xia, Shouzhi Pu*
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science & Technology Normal University,
Nanchang 330013, PR China
*Corresponding author: E-mail address:
zhangdaobin2006@sina.com (D.B. Zhang);
pushouzhi@tsinghua.org.cn (S.Z. Pu); Tel./Fax: +86-791-83831996
A cyclometalated iridium(III) complex comprised 2,4-dinitrobenzenesulfonamide (DNBS) as the
recognition unit (probe 1) was synthesized and its fluorescent behaviors toward thiophenols in
20% DMSO/PBS solution and water samples were investigated systematically. The results
demonstrated that probe 1 could serve as a sensitive and selective fluorescent probe to detect
thiophenols and could not be disturbed by aliphatic thiols.

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Iridium(III) complex-based fluorescent probe for detection
of thiophenols and its application in water samples
Haiyue Lu, Daobin Zhang*, Congbin Fan, Yaqian Guo, Xiaoli Xia, Shouzhi Pu*
Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science & Technology Normal University,
Nanchang 330013, PR China
*Corresponding author: E-mail address:
zhangdaobin2006@sina.com (D.B. Zhang);
pushouzhi@tsinghua.org.cn (S.Z. Pu); Tel./Fax: +86-791-83831996
Abstract
In consideration of the nucleophilic capacity of thiophenols, which could cleave sulfonamide
under neutral conditions, a cyclometalated iridium(III) complex (probe 1)
comprised
2,4-dinitrobenzenesulfonamide (DNBS) as the recognition unit was designed and synthesized to
high selectivity and sensitivity detect thiophenols successfully based on internal charge transfer
(ICT) mechanism. Upon addition with thiophenols to 20% DMSO/PBS solution of nearly
non-fluorescent probe 1 (10 µM, pH = 7.4), fluorescent product (complex 2) was formed after
cleavage of DNBS group and a significant emission enhancement at 470 nm was observed. In
addition, it could be successfully applied to detect thiophenol in water samples with a high
recovery, confirming its practical value in environment science.
Keywords: Thiophenol; Fluorescent probe; Iridium(III) complex; 2,4-dinitrobenzenesulfonamide.

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1. Introduction
Thiophenols are important raw materials for medicine [1], pesticide [2], polymer [3] and
additives on organic synthesis [4]. However, their potential hazards, such as volatility, foulsmell
and high toxicity to biological and ecological environment, also can not to be ignored. For
instance, thiophenols possess very low median lethal concentration (LC50) and dose (LD50) for fish
(0.01-0.04 mM) [5] and mouse (2.15-46.2 mg kg-1) [6]. Long term exposure of either liquid or
vapor of thiophenols to human beings may cause several symptoms, such as central nervous
system lesion, difficulty breathing, muscle weakness, paralysis, coma and even death [7-9].
Therefore, development of a highly sensitive and selective detection method for thiophenols in
environmental and even in biological samples is highly demanding. At present, high performance
liquid chromatography [10], gas chromatography [11], nonlinear spectroscopy [12] and nanophase
material sensor based methods [13-14] have been used to detect the concentration of thiophenols,
but complicated sample preparation, low sensitivity, easy interference and expensive instruments,
and non-real-time online monitoring limit their further applications. Meanwhile, fluorescent
analysis has attracted wide attention due to its advantages of simple operation, rapid response,
high sensitivity and selectivity, and even direct detection in living cells or tissues [15-18]. Among
the researches on detection of thiophenols, it is noteworthy that aliphatic thiols maybe become a
potential interference factor because of their similar chemical structure, the same activity function
thiol group (-SH). Fortunately, the different pKa value between thiophenols (pKa = 6.5) and
aliphatic thiols (pKa =8.5) (Scheme 1) under neutral conditions provide an approach to
discriminate thiophenols from thiols [19]. Thiophenols can produce more nucleophilic thiolate
species in the neutral reaction medium to achieve SNAr process and cleave sulfonamide, but under

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the same reaction conditions, aliphatic thiols are difficult to hydrolyze, thus realizing the purpose
of distinguishing aliphatic thiols from aromatic thiols.
<Scheme 1>
Since Jiang [19] synthesized the first fluorescence probe for specifically recognition
thiophenol without alkyl mercaptan interference, many similar probes have been synthesized in
the last decade, but most of them are small organic molecule probes [20-30]. The studies of
fluorescent probes containing metal complex structures have been not much reported [31-32].
Usually, transition organometallic probes possess the following characteristics: (1) highly
luminous efficiency, long life and high stability; (2) large stokes shift of excitation and emission,
and easy regulation of excitation and emission wavelength; (3) low cell imaging incubation
concentration, and less interference of cell normal activity [33]. Meanwhile, because of easy
functionalized modification and synthesis, photochemical stability, and desirable photophysical
properties [34-43], cyclometalated Ir(III) complexes are widely used as excellent luminescent
materials for various applications, such as sensing and bioimaging [33,44], organic light-emitting
devices [45], and sensitized photon upconversion [46].
It is well known that a responsive fluorescence probe usually include a fluorescent unit and a
switch moiety sensitively regulating to various substrates, such as metal ions, anions and amino
acids, and so on. Generally, these fluorescence switches strategy is proposed to induce efficient
transfer processes, such as internal charge transfer (ICT), photoinduced electron transfer (PET),
electronic energy transfer (EET), and monomer-excimer formation (MEF) [31]. Herein, we
introduced cyclometalated iridium(III) complex as fluorophore and electron-withdrawing
2,4-dinitrobenzenesulfonyl (DNBS) group as recognition unit, then successfully synthesized a

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probe 1 in order to detect thiophenols. Due to the influence of internal charge transfer (ICT) from
cyclometaled iridium moiety to strongly electron-withdrawing DNBS moiety, probe 1 exhibits
nearly non-fluorescence. When the cleavage of DNBS group occur through reaction between
complex 1 and thiophenols, the luminescence of Ir( ) complex 2 could be recovered. Probe 1 was
found to high selectivity and sensitivity response to thiophenols accompanied with obvious
fluorescent turn-on around 470 nm. In addition, this probe was also successfully applied to
quantitative detection of thiophenols in water samples.
2. Experimental Section
2.1 General procedures and materials
All chemical materials were purchased through commercial channels and were not further
purified, except those with further notice. All solvents were purified by standard methods prior to
use. All the synthetic operations were performed under a dry argon atmosphere using Schlenk
techniques and a vacuum-line system. The solution of probe 1 (1 mM) was prepared in
chromatographic grade THF. Standard solution of various analytic samples (10 mM) were
prepared after dissolution of C6H5SH, p-Cl-C6H5SH, p-CH3-C6H5SH, p-CH3O-C6H5SH,
p-NH3-C6H5SH, HOCH2CH2SH, PhOH, (CH3)3SH and PhNH2 into DMSO. Solutions of
glutathione (GSH), cysteine (Cys), homocysteine (Hcy), alanine (Ala), glycine (Gly), NaSH and
KI were prepared in distilled water (10 mM, respectively).
2.1.1 N,N-diphenyl-4'-(pyridin-2-yl)-[1,1'-biphenyl]-4-amine (4)
In a 250 mL round-bottom flask, 2-(4-bromophenyl)pyridine (2.671 g, 11.41 mmol),
Pd(PPh3)4 (250 mg) and (4-(diphenylamino)phenyl)boronic acid (3.00 g, 10.38 mmol) were
dissolved in 125 mL of THF, then Na2CO3 (12.72 g, 120 mmol) prior dissolved in 60mL water

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was added to the mixture solution. After reaction solution was stirred at 80 for 12 h, solvent
THF was evaporated, and the obtained solution was extracted with dichloromethane, which was
removed under reduce pressure to get yellow crude product. Crude product was purified by
column chromatography on SiO2 with petroleum ether and ethyl acetate (v/v = 20:1) as eluent to
obtained 3.568 g faint yellow solid in 86.2 % yield. 1H NMR (400 MHz, DMSO, ppm) δ: 8.73 (d,
J = 4.4 Hz, 1H), 8.21 (d, J = 8.4 Hz, 2H), 8.06 (d, J = 8.0 Hz, 1H), 7.94 (t, J = 7.8 Hz, 1H), 7.82 (d,
J = 8.4 Hz, 2H), 7.74 (d, J = 8.4 Hz, 2H), 7.39 (t, J = 7.6 Hz, 5H), 7.13 (q, J = 7.8 Hz, 8H);
HRMS: m/z 399.1839 [M + H]+.
2.1.2 Chloro-bridged Ir (Ⅲ) complex dimer (3)
In a 100 mL round-bottom flask, compound 4 (0.445g, 1.1176 mmol) and anhydrous IrCl3
(0.152g, 0.508 mmol) were added to 20 mL of 2-ethoxyethanol and water (v/v = 3:1) and the
solution was refluxed for 25 h. The solution was filtered after cooling to room temperature, the
resulting precipitate was in turn washed with 10 mL 95% ethanol, acetone, to afford crude dimer 3
0.43g as yellow solid in 82.8 % yield, which was used to next reaction directly without further
purification and characterization [47,48].
2.1.3 Complex 2
To a mixture of cyclometalated Ir(III) chloro-bridged dimer 3 (0.36 g, 0.176 mmol),
1,10-phenanthrolin-5-amine (0.0687 g, 0.352 mmol) in 50mL of CH2Cl2/CH3OH (v/v = 1:1) were
reflux 6 h. After completion of the reaction, solvent was evaporated, crude product was purified
by neutral alumina column chromatography using CH2Cl2/CH3OH (v/v = 30:1) as eluent and
1
obtained 0.385 g red solid in 89.8 % yield. H NMR (400 MHz, DMSO, ppm) δ: 9.08 (d, J = 8.4
Hz, 1H), 8.40 (d, J = 8.4 Hz, 1H), 8.25 (t, J = 4.2 Hz, 3H), 8.00-7.95 (m, 3H), 7.87 (t, J = 7.6 Hz,

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3H), 7.73-7.70 (m, 1H), 7.50 (t, J = 6.8 Hz, 2H), 7.29 (t, J = 7.6 Hz, 13H), 7.19 (s, 1H), 7.13 (s,
1H), 7.05 (t, J = 7.4 Hz, 5H), 6.99 (d, J = 8.0 Hz, 10H), 6.90 (d, J = 7.2 Hz, 5H), 6.51 (d, J = 12.4
Hz, 2H, -NH2); 13C NMR (100 MHz, DMSO, ppm) δ: 184.03, 167.45, 167.14,167.06, 151.73,
151.30, 150.89, 149.57, 149.32, 147.51, 147.40, 145.97, 145.64, 143.51, 143.46, 141.01, 140.95,
140.33, 139.07, 136.77, 135.51, 134.36, 134.09, 133.70, 132.42, 132.03, 130.06, 192.12, 128.58,
128.45, 128.26, 127.69, 127.10, 126.06, 126.00, 125.93, 124.71, 124.51, 124.10, 124.07, 123.82,
123.45, 121.29, 121.02, 120.97, 120.66, 120.49, 120.43, 109.06, 108.76, 102.22; HRMS: m/z
1182.3739 [M − Cl]+.
2.1.4 Complex 1
Under an argon atmosphere, complex 2 (0.10 g, 0.0821 mmol) was dissolved in 10 mL of dry
THF and cooled to 0 , followed by addition of NaH (5.00 mg, 60% in purity, 0.125 mmol). Upon
stirring for 15 min, 2, 4-dinitrobenzenesulfonyl chloride (0.033 g, 0.125 mmol) in 5 mL dry THF
was added dropwise. The resulting reaction mixture was then further stirred at room temperature
for another 1 h. After solvent was evaporated, crude product was purified by column
chromatography on SiO2 with CH2Cl2/ acetone (v/v = 3:1) as eluent to obtained 0.035 g red solid
in 29.6 % yield. 1HNMR (400 MHz, DMSO, ppm) δ: 10.56 (s, 1H, -NH), 8.99 (s, 1H, phenyl-H),
8.89 (d, J = 8.4 Hz, 2H), 8.55 (d, J = 2.4 Hz, 1H), 8.53 (s,1H), 8.40-8.37 (m, 2H), 8.34-8.29 (m,
3H), 8.10-8.00 (m, 5H), 7.92 (m, 2H), 7.57 (t, J = 7.0 Hz, 2H), 7.31 (t, J = 8.0 Hz, 13H), 7.14 (d, J
= 9.6 Hz, 1H), 7.07 (t, J = 6.8 Hz, 6H), 7.01 (d, J = 7.6 Hz, 9H), 6.95-6.92 (m, 4H), 6.54 (s, 2H);
13C NMR (100 MHz, DMSO, ppm) δ: 167.09, 151.88, 151.39, 150.73, 150.55, 149.76, 149.69,
148.02, 147.87, 147.79, 147.57, 147.46, 147.40, 146.92, 146.04, 145.34, 143.47, 141.05, 139.27,
139.09, 139.02, 137.80, 136.77, 135.68, 135.60, 134.00, 133.61, 132.84, 132.44, 132.10, 131.27,

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131.13, 130.08, 129.73, 129.13, 128.53, 127.96, 127.72, 126.06, 125.85, 124.75, 124.14, 124.10,
123.87, 123.59, 123.42, 121.53, 121.17, 120.59, 118.75, 118.61, 109.06, 108.76; HRMS: m/z
1348.3910 [M − Cl − C6H3N2O4 + Na + K + CH3CN]+; IR (KBr, υ, cm−1): 1335 (−S=O), 1586
(−NO2), 3448 (−N-H).
2.2 Physical measurements
NMR spectra were recorded on a Bruker AV400 (400MHz) spectrometer with (CD3)2SO as
solvent and tetramethylsilane (TMS) as internal standard. Mass spectra data were obtain with an
Agilent 1100 ion trap MSD spectrometer. Absorption spectra were measured on an Agilent 8453
UV–vis spectrometer. Infrared spectra (IR) were collected on a Bruker Vertex-70 spectrometer as
KBr pellets and were reported in cm−1. Fluorescence spectra were recorded on a HitachiF-4600
fluorescence spectrophotometer with the excitation and emission slit widths of 5.0 nm and 5.0 nm.
2.3 Measuration of thiophenol in real water samples.
The crude water samples were obtained from Ganjiang River, Kong Mu Lake and Qingshan
Lake in Nanchang city, further adapted as through using sodium phosphate buffer (10 mM, pH =
7.4). Aliquots of water sample were then spiked with different concentrations of thiophenol (1, 5,
10, 20 µM) that had been accurately prepared. The sequent samples were further treated with
probe 1 in 20% DMSO phosphate buffer (10 mM, pH = 7.4) to obtain final mixtures (2.0 mL)
with probe 1 and thiophenol (1, 5, 10, 20 µM). The mixtures were incubated for 40 min at 25 °C,
and emission intensity at 470 nm was recorded. The results were reported as the mean ± standard
deviation of triplicate experiments.
3. Results and discussion
3.1 Synthesis and Characterization

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The synthetic route of probe 1 was displayed in scheme 2. Ligand 4 was obtained through
classic Suzuki cross coupling reaction between 2-(4-bromophenyl)pyridine and
(4-(diphenylamino)phenyl)boronic acid. Chloried-bridged complex 3 was synthesized from
reaction of ligand 4 with anhydrous IrCl3 without further purification, followed by treating with
1,10-phenanthrolin-5-amine in presence of CH2Cl2/CH3OH to afford complex 2. Probe 1 was
prepared through reaction of complex 2 with 2,4-dinitrobenzenesulfonyl chloride in the presence
of NaH playing as a deprotonation reagent. Because of the activity of NaH, the deprotonation
procedure was carried out at 0 °C. All compounds were characterized by NMR, ESI-HRMS.
<Scheme 2>
3.2 UV absorption and fluorescence emission studies
The absorption spectra of probe 1 and complex 2 were carried out in DMSO solution (10µM)
at room temperature. Both of them showed two sharp absorption bands around at 289 nm and 380
nm ascribe to intra-ligand-centered π → π* transitions and metal to ligand charge transfer (MLCT)
transitions, respectively (Fig.1A) [49]. The MLCT absorption band displayed properly high molar
extinction absorption coefficient (log ε = 4.93) that was much higher than that of MLCT transition
of other reported [Ir(ppy)2bpy]+-form complexed (log ε = ca. 3.0) [50]. This excellent MLCT
transitions property of probe 1 would be conducive to improve fluorescence character and increase
sensitivity of the probe. The absorption spectra between probe 1 and complex 2 had almost no
difference, suggesting that the cyclometalated [Ir(ppy)2Phen]+ moiety did not participate in
recognition process and fluorescence of probe 1 should be probably quenched via ICT mechanism
[31]. On the other hand, fluorescence spectra of probe 1 and complex 2 were quite different. As
shown in Fig. 1B, when excited at 400 nm, complex 2 exhibited fluorescence emission band at

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470 nm (Φ = 0.04). After connecting electron-withdrawing 2,4-dinitrobenzenesulfonyl (DNBS)
group, probe 1 showed almost non-fluorescence (Φ = 0.003) because of ICT mechanism.
<Fig. 1>
3.3 Fluorescence response of probe 1 toward thiophenol
Although with non-fluorescence property (Φ of 1 was 0.003), when added 10 equivalents of
thiophenol to DMSO/PBS (v/v = 1:4) solution of probe 1 to form corresponding fluorescent
complex 2 (Φ = 0.04), an emission peak at 470 nm was obviously observed and the fluorescence
intensity increased significantly and reached maximum after 40 minutes, implying probe 1 could
serve as a quite sensitive fluorescent sensor for thiophenol (Fig. 2A). Meanwhile, time response
capability of probe 1 for thiophenol was further investigated in 0.01 M 20% DMSO/PBS with
fluorescence spectroscopy to evaluated kinetic studies. As depicted in Fig. 2B, upon addition of
thiophenol (100 µM), the fluorescence intensity at 470 nm showed a rapid increase initially (0 –
10 min), and reached an equilibrium within 40 minutes with a relatively moderate kinetic constant
(k = 0.10043 min-1) and half-time (t1/2 ≈ 6.90 min, Fig. S5, see SI). Although this value of
half-time was only relatively medium, considering the emission intensity at 470 nm enhanced
rapidly in the first ten minutes, we still thought that probe 1 could be able to rapidly response to
thiophenol.
<Fig. 2>
Moreover, detailed fluorometric titration experiments were carried out in 20% DMSO/PBS
(0.01 M, pH = 7.4) to further investigate the responsive fluorescence of probe 1 induced by
thiophenol (Fig. 3). As shown as Fig.3 (Inset: its emission intensity curve at 470 nm with addition
of various equiv thiophenol), with addition of less than 3 equiv of thiophenol, fluorescence

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intensity of probe 1 enhanced significantly initially, as thiophenol was further added gradually, the
emission intensity increased slowly and finally reached a plateau when 10 equiv of thiophenol was
further titrated. The fluorescence intensity at 470 nm exhibited an excellent linear relationship
with the concentration of thiophenol in range of 0 − 30 µM (Fig. 3B), whose slope was calculated
to be 1.141 × 10-6 M (R = 0.99942). This indicated that probe 1 could be potentially used for
quantitative detection of thiophenol. According to previous method defined by IUPAC [51-54],
the limit of detection (LOD) was calculated to be 1.65 × 10−6 mol L−1, demonstrating that our Ir( )
complex-based probe 1 could be sensitive detection of thiophenol (Table S1, see SI).
<Fig. 3>
3.4 Selectivity of probe 1 toward thiophenols
As we known, discrimination thiophenol from aliphatic thiols was a requisite capability for
thiophenol probe. In order to explore the specificity of probe 1 toward thiophenols, fluorescence
responsive reaction of probe 1 with various analytes, including thiophenol derivatives (C6H5SH,
p-CH3-C6H4SH, p-Cl-C6H4SH, p-NH2-C6H4SH and p-CH3O-C6H4SH), aliphatic mercaptan
(HOCH2CH2SH, (CH3)3CSH, cysteine (Cys), homocysteine (Hcy) and glutathione (GSH)), and
other nucleophilic substances (C6H5NH2, C6H5OH, KI, NaSH, glycine (Gly) and alanine (Ala)),
were evaluated under similar conditions. As depicted in Fig. 4, when various analytes were added
into probe 1 20% DMSO/PBS solution, only thiophenol derivatives could induced obvious
fluorescence enhancements, indicating that probe 1 was not susceptible influence by these
interfering substances. When 10 equivalent thiophenol derivatives were added to the mixture of
probe 1 and previous interfering substances, fluorescence enhancements were observed. These
results indicated that probe 1 possessed an excellent specificity for thiophenols.

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<Fig. 4>
3.5 Probing mechanism of Ir − DNBS toward thiophenols
Similar to the previously reported thiophenol probe with 2,4-dinitrobenzenesulfonyl as
recognition group, the sulfonamide bond of probe 1 could also be broke through SnAr process
induced by thiolate. To further elucidate the recognize mode between probe 1 and thiophenol, a
1
series of H NMR experiments were recorded. As shown in Fig. 5, upon addition 10 equiv of
thiophenol to probe 1 in DMSO-d6, the proton signal of Ha at 10.56 ppm corresponding to the
2,4-dinitrobenzenesulfonamide group (−N-H) of probe 1 disappeared due to the cleavage of
sulfonamide bond. Meanwhile, H1 at 8.99 ppm, H2 at 8.53 ppm and H3 at 8.15 ppm ascribed to
protons on benzene ring of 2,4-dinitrobenzenesulfonamide group showed slight shift to 9.04 ppm,
8.57 ppm and 7.18 ppm, respectively, which was more consistent with the characteristic proton
signals of (2,4-dinitrophenyl) (phenyl) thioether (DN). These results confirmed that probe 1
generated complex 2 as the luminescent species and DN as the byproduct through a thiolate
triggered SnAr cleavage process.
<Fig. 5>
3.6 Detection of Thiophenols in Water Samples.
Whereas toxicity of thiophenols and their harms to environment, we employed probe 1 to
quantify thiophenol concentrations in water samples to evaluate the practicability of probe 1 in
environmental science according to standard addition method [6,27,28]. The crude water samples
were obtained from Ganjiang River, Kong Mu Lake and Qingshan Lake in Nanchang city. These
water samples were spiked with different concentrations of thiophenol (1, 5, 10, 20 µM), obvious
fluorescence was observed and their responsive fluorescence intensity at 470 nm in various water

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samples were recorded (Table 1). The thiophenol recovery could be accurately measured and
ranged on 90–104%, suggesting that probe 1 had potential application for quantitative detection of
thiophenols in water samples.
<Table 1>
4. Conclusions
In summary, an iridium (III) complex (1) was successfully designed and synthesized as a
probe to highly selective and sensitive detection of thiophenols. Its recognition behaviors and
mechanism, in which iridium (III) complex (2) as the fluorophore and
2,4-dinitrobenzenesulfonamide as the reaction group through internal charge transfer (ICT), was
1
also confirmed by fluorescence spectroscopy and H NMR experiments. The advantages of this
probe in detecting thiophenols contained relatively quick (t1/2 ≈ 6.90 min) and obvious
fluorescence responses (6-fold enhancement), high selectivity and sensitivity. Moreover, probe 1
can be used for the quantitative detection of thiophenols in water samples. Therefore, probe 1 had
potential applications for fast detection and quantification of thiophenols in environmental
systems.
5. Acknowledgements
The authors are grateful for the financial support from the National Natural Science
Foundation of China (21701065, 41867053, 21861017), the “5511” science and technology
innovation talent project of Jiangxi (2016BCB18015), the Science Funds of Natural Science
Foundation of Jiangxi Province (20171ACB20025), the Project of Science Funds of Jiangxi
Education Office (GJJ170690).

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Figures & captions
Scheme 1. Nucleophilicity of thiophenols and aliphatic thios under neutral condition.
Scheme 2. Synthetic routes of complex 1
Fig. 1. (A) Absorption spectra of probe 1 (10 µM), complex 2 (10 µM) in DMSO at room
temperature; (B) Fluorescence sprctra of probe 1 (10 µM), complex 2 (10 µM) in 20% DMSO/PBS
at room temperature.
Fig. 2. (A) Changes in fluorescence of probe 1 (10 µM) in 20% DMSO/PBS (0.01 M, pH = 7.4)
induced by 100 µM thiophenol at different reaction time, excited at 400 nm (slit: 5/5); (B) Time
response curves at 470 nm of probe 1 (10 µM in 0.01 M 20% DMSO/PBS, pH = 7.4) with
thiophenol (100 µM).
Fig. 3. (A) Changes in fluorescence of probe 1 (10 µM) in 20% DMSO/PBS (0.01 M, pH = 7.4)
induced by different concentrations of thiophenol (0 − 10 equiv), excited at 400 nm (slit: 5/5).
Each spectrum was collected 40 minutes after addition of thiophenol; (B) Linear relationship
between fluorescence intensity of probe 1 (10 µM) at 470 nm and the concentration of thiophenol
from 0 to 30 µM.
Fig. 4. (A) Emission spectral changes in fluorescence of probe 1 (10 µM) induced by various
analytes (10 equiv) in 20% DMSP/PBS (0.01 M, pH = 7.4), excited at 400 nm (slit: 5/5). Each
spectrum was collected 40 minutes after addition of analyte; (B) Competitive tests on fluorescent
responses of probe 1 at 470 nm to various analytes in 20% DMSO/PBS (0.01 M, pH = 7.4). Black
bars represent the addition of 10 equiv of various analytes to solution of probe 1. Red bars
represent the addition of thiophenol (10 equiv) to the above solution.
Fig. 5. Partial 1H NMR spectra of probe 1, probe 1 + thiophenol (10 equiv), complex 2 and DN in

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DMSO-d6.
Table 1. Determination of thiophenol concentrations in water samples

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Scheme 1

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Scheme 2

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Fig. 1

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Fig. 2

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Fig. 3

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Fig. 4

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Fig. 5