Determination of thallium(iii) ions by oxidative hydrolysis of rhodamine-hydroxamate

Article abstract of DOI:10.1039/d0nj05002d

Thallium ions are widely used in chemical and industrial applications but are very toxic. Through this research, a novel dual signaling probe that is based on an oxidative cleavage reaction is examined. The probe showed selective and sensitive optical sig

Full text of DOI:10.1039/d0nj05002d

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Determination of thallium(III) ions by oxidative
hydrolysis of rhodamine–hydroxamate†
Cite this: New J. Chem., 2021,
45, 603
Jae Hoon Yoo, Yu Jeong Lee, Kang Min Lee, Myung Gil Choi,
and Suk-Kyu Chang
Tae Jung Park
*
*
Thallium ions are widely used in chemical and industrial applications but are very toxic. Through this research,
a novel dual signaling probe that is based on an oxidative cleavage reaction is examined. The probe showed
3+
selective and sensitive optical signaling behavior toward TI through the oxidative hydrolysis of rhodamine–
hydroxamate. The probe designed for this study exhibited a distinct colorimetric and fluorescence signaling
activity for thallium ions compared to the ions of common metals and oxidants. In particular, the hypochlorous
acid response of the probe was successfully suppressed using DMSO as a scavenger. The detection limit for
Received 12th October 2020,
Accepted 25th November 2020
À7
thallium determination was 2.9 Â 10 M and signaling was concluded within 5 minutes. The exploitation
DOI: 10.1039/d0nj05002d
of the probe for the rapid screening of elevated urinary thallium levels due to thallium poisoning using
smartphone images was also conducted.
rsc.li/njc
of thallium results in acute poisoning, which is principally
1
. Introduction
diagnosed by gastrointestinal, neurological, and dermatological
7
Thallium is a highly hazardous metal, and its toxicity is well indications. In cases of acute thallium poisoning, blood and
1
recognized in the environmental and medical science fields.
urine thallium concentrations are significantly elevated. Reliable
+
Thallium metal is most commonly found as thallous (Tl ) and thallic diagnosis of thallium poisoning occurs when thallium levels in
3+
À1
À7
(
Tl ) ions and is more toxic than other heavy metal ions such as the blood exceed 50 mg L (2.45 Â 10 M) or when the levels
2
À1
À
6
8
cadmium and mercury. The United States Environmental Protec- surpass 300 mg L (1.47 Â 10 M) in the urine. In humans,
tion Agency (USEPA) lists thallium as a major pollutant owing to its the reference ranges for thallium in both blood and urine is
3
À8
9
hazardous nature. However, there is an increasing demand for 2.45 Â 10 M. Inductively coupled plasma mass spectrometry
thallium in high-technology electronic, chemical, aerospace, phar- (ICP-MS) and atomic absorption spectrometry are the routinely
maceutical, and optical industries for applications such as high- used methods to measure thallium levels in blood and urine
4
8,10
temperature superconducting and high-energy physics materials.
samples that are suitable for diagnosis.
In fact, thallium
Thallium is a potent oxidizing agent in synthetic chemistry. It has has been traditionally determined by various instrumental
11
wide application in the oxidation and oxidative rearrangements of methods, such as voltammetry/potentiometry, atomic absorption
1
2,13
14,15
16
ketones, olefins, acetylenes, and compounds containing double spectrometry,
bonds between carbon and nitrogen. Owing to its widespread ICP-MS
spectrophotometry,
fluorimetry, and
5
17,18
which has become one of the most popular techniques
use, it is now estimated that 2000–5000 tons of thallium species in recent years. However, it is more advantageous to use colori-
per year are released by industrial processes such as mineral metric or fluorescence analysis methods than these procedurally
processing (including cement production and recycling of concrete) complicated heavy instrument-based methods.
6
and as waste from the electric or electronic industries. It is highly
Several colorimetric assays based on the extraction using chloro-
imperative to minimize the current environmental concerns regard- substituted hydroxamic acid and 2,6-bis(N-phenyl carbamoyl)pyri-
1
4,19
20
ing thallium by developing selective and sensitive monitoring dine have been reported.
methods to protect humans from this poisonous species. and oxidative coupling reaction of 3-methyl-2-benzothiazolinone
Also, oxidation of trifluoperazine
21
3
+
Long-term exposure to thallium causes chronic poisoning. On have been used as a colorimetric Tl determination method.
the other hand, accidental or short exposure to high concentrations On the other hand, only a few fluorescence assays exist for
thallium speciation and determination. Representative examples
Department of Chemistry, Chung-Ang University, Seoul 06974, Republic of Korea.
are the catalytic kinetic method employing arsenoxylphenylazo
E-mail: tjpark@cau.ac.kr, skchang@cau.ac.kr; Fax: +82 2 825 4736;
Tel: +82 2 820 5199
22
+ 23
rhodanine and the native fluorescence of reduced Tl . Alter-
natively, the sulfonhydrazide of a rhodamine–dansyl conjugate
is used for the colorimetric and off–on type fluorescence signal-
†
Electronic supplementary information (ESI) available: UV-vis and fluorescence
1
13
data, H and C NMR spectra of probes (1–3) were reported. See DOI: 10.1039/
2
4
d0nj05002d
ing by cleaving the linkage through oxidation. The analytical
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3
+
characteristics of the reported Tl signaling methods including Silica gel (240 mesh, Merck) was used to perform column
their applications are summarized in Table S1 (ESI†). chromatography. Probes 1 and 2 were prepared by following
3+
33,34
We attempted to create a new Tl probe that is based on selective the reported procedures.
reactions and shows distinct colorimetric and fluorescence signals
through the exploitation of the complex forming and oxidative
hydrolytic characteristics of hydroxamic acid. Many hydroxamic
acid-functionalized compounds have been employed as the basis
of analytical methods based on their complex formation capability
2
.2 Preparation of compound 3
Dichloromethane (40 mL) was used to dissolve rhodamine hydro-
xamic acid 1 (0.86 g, 2.0 mmol) and trimethylamine (0.546 mL,
4
.0 mmol). Acetyl chloride (0.284 mL, 4.0 mmol) was added
gradually to the mixture. Afterwards, the mixture was stirred at
5 1C for 12 h. Brine and distilled water were used to wash the
2+
2+ 25
2+ 3+ 26
with a range of metal ions, such as Cu /Ni , UO
2
/Al , and
3+
3+ 27
Fe /Ga . In particular, applications in chelation therapy are
noteworthy. The best known chelation therapy application is
2
reaction mixture multiple times and reduced pressure was used
to evaporate the solvent. Compound 3 (0.36 g, 38%), a light brown
solid, was obtained by the purification of the precipitate using a
3
+
the formation of hydroxamate complexes with Fe ions, such as
desferrioxamine B, for the treatment of toxic side effects of iron-
2
8–31
overloaded thalassemia patients.
Interestingly, a chelating
column chromatogram with silica gel and dichloromethane.
agent containing a hydroxamic acid ligating group has also been
1
H NMR (600 MHz, DMSO-d ) d 7.95 (d, J = 6.6 Hz, 1H), 7.54–
3
+
6
used for the detoxification of Tl by enhanced excretion through
7.43 (m, 2H), 7.05 (d, J = 5.2 Hz, 1H), 6.48 (s, 2H), 6.34 (s, 2H), 3.20
3
2
urine and feces in rats.
(
q, J = 7.3 Hz, 4H), 1.98 (s, 3H), 1.93 (s, 6H), 1.31 (t, J = 6.9 Hz, 6H);
Notably, several hydroxamate-based colorimetric and fluorogenic
probes derived from rhodamine dyes have been designed for
1
3
3
C NMR (150 MHz, CDCl ): d 166.80, 162.95, 152.03, 150.89,
147.55, 133.25, 128.89, 128.33, 127.79, 123.82, 123.30, 117.60,
3
3
the sensing of hypochlorous acid, hypervalent iodine reagent
+
104.55, 96.38, 65.81, 38.33, 18.06, 16.71, 14.74; HRMS (ESI , m/z):
3
4
2
-iodoxybenzoic acid (IBX), and nerve gas agents using Lossen
+
+
30 3 4
calculated for C28H N O [M + H] : 472.2231, found 472.2234.
3
5
rearrangement. Further modification of the basic framework of
rhodamine–hydroxamate has led to the selective sensing of
many metal ions, for instance, Fe by introducing a methyl
3
+
2.3 Preparation of stock solutions
3
6
2+
group on the hydroxy function, Hg by thio-functionalization A spectroscopy-level DMSO was used to prepare stock solutions of
3
7
2+
À4
of the hydroxamate moiety, Pd by appending a cyclen probes (5.0 Â 10 M). HCl (0.05 M) was used to prepare a stock
3
8
2+
39
À2
ligand, and Pt by conjugating a triazole ligand. These solution of thallium(III) ions (1.0 Â 10 M). The stock solutions
À2
and other interesting rhodamine hydroxamate-based signaling of metal ions (1.0 Â 10 M) were prepared in distilled water.
systems for many important chemical species have recently been A method from previous reports was used to prepare synthetic
4
0
42,43
comprehensively reviewed.
urine.
3+
Here, we report a new Tl -selective reaction-based optical probe
that works through hydroxamate-to-carboxylic acid oxidative hydro-
2.4 Measurement of signaling behavior
3+
lysis. The Tl -assisted conversion of rhodamine–hydroxamate into
ring-opened parent rhodamine dye induced substantial changes in
the optical properties of the probe. The practical applicability of the
probe for early screening of elevated urinary thallium levels in
acute poisoning cases employing a ubiquitous smartphone with
simulated urine was also carried out.
The conditions for thallium(III) ion signaling experiments were
adjusted using a mixture of acetate buffer solution with a pH of
À4
4
.2 and 30% (v/v) DMSO. Probe 1 (30 mL, 5.0 Â 10 M) and
3+
À2
analyte (Tl , metal ion, oxidant, or anion; 45 mL; 1.0 Â 10 M)
stock solutions and acetate buffer with a pH of 4.2 (150 mL, 0.20 M)
were added to a vial. Also, to equalize the conditions of measure-
ment of the sample solutions, 45 mL of 0.05 M HCl solution (same
volume used for Tl ) was added to all samples. The resulting
mixture was used to make a measuring solution (3.0 mL, 7 : 3 (v/v)
mixture of acetate buffer and DMSO) through dilution using DMSO
and distilled water. The final concentration for the analyte and
3+
2. Experimental
2.1 General
Thallium(III) nitrate trihydrate, rhodamine 6G, rhodamine B
base, and hydroxylamine hydrochloride were purchased from
Merck KGaA. Other reagents, solvents, and metal perchlorates
were obtained from commercial sources. Thallium(III) nitrate
À4
À6
probe 1 was 1.5 Â 10 M and 5.0 Â 10 M, respectively, while
À2
that of the buffer was 1.0 Â 10 M.
3
+
4
1
2.5 Preparation of Tl signaling product 1
trihydrate was used after standardization via iodometry.
1
A Varian VNS NMR spectrometer was used to record H and After dissolving probe 1 (43 mg, 0.01 mmol) in a 10 mL solution
C NMR spectra (600 MHz and 150 MHz, respectively). Scinco of acetonitrile, thallium(III) nitrate trihydrate (89 mg, 0.02 mmol)
1
3
S-3100 and FS-2 spectrophotometers were used to measure was added to 1.0 mL of 0.1 N HCl. This reaction mixture was
UV-vis and fluorescence spectra, respectively. A Micromass Auto- stirred for 1 hour after which 10 mL of dichloromethane was
spec mass spectrometer with electron ionization (EI) was used to added. The organic phase was separated and evaporated
extract mass data that had a low resolution. Mass outcomes of under reduced pressure. Purification of signaling product 4
high resolution were acquired using Bruker Compact mass was carried out by column chromatography (silica gel,
2 2 3
spectrometer with a fast-atom bombardment (FAB) ionization. CH Cl : CH OH = 9 : 1, v/v).
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.6 Determination of the detection limit of Tl
Paper
3
+
2
3+
Calculation of the detection limit of Tl ions was performed by
applying the equation (3sbl/m), where sbl is the standard deviation
of the blank measurement (n = 12) and m is the calibration
sensitivity obtained from the slope of the calibration plot according
44
to the IUPAC recommendations.
3
+
2
.7 Determination of Tl in synthetic urine using a
smartphone
The reported literature was used as the foundation for determining
3+
45
Tl ions in synthetic urine using a smartphone. The smartphone
is used as a readily available tool for measuring and processing
signals. The conditions for all the experiments were adjusted
using an acetate buffer solution with a pH of 4.2 containing 30%
Scheme 1 Synthesis of probes 1 and 2 and acetylated derivative 3.
(
v/v) DMSO.
overlap. Furthermore, the response of hypochlorous acid could
readily be suppressed by relying on the scavenging effect of
DMSO. The reaction between rhodamine 6G and rhodamine B
base with hydroxylamine hydrochloride was used to prepare
A. Preparation of sample solutions. Samples were prepared
3
+
through the addition of acetate buffer (150 mL, 0.20 M), Tl
À4
stock solution (0, 7.5, 15, 22.5, and 30 mL, 5.0 Â 10 M), and
À4
probe 1 (30 mL, 5.0 Â 10 M) into a 10 mL vial. Distilled water
3
3,34
probes 1 and 2, respectively (Scheme 1).
obtained by the acetylation of 1.
Compound 3 was
and DMSO (3.0 mL, 7 : 3 (v/v)) were then used to dilute the
resulting solution. The final concentration of the probe in the
UV-vis and fluorescence experiments were used to examine
À6
À2
3+
solution was 5.0 Â 10 M, the buffer 1.0 Â 10 M, and the Tl
3
+
the Tl signaling properties of the probe. To gain insight into
the optimized structure of the probe, two similar but differently
structured rhodamine-based hydroxamic acids (1 and 2) and one
À6
ions 0–1.0 Â 10 M.
3
+
B. Determination of Tl using a smartphone. A cuboid
with a square hole in the lid was used to measure the response
of the samples. A Galaxy S10 smartphone, Samsung Electronics
model, with no special settings, was used to take photographs
of the samples under a hand-held UV lamp, VILBER, VL-4LC
model. The RGB Grabber, Shunamicode smartphone application
was used to estimate the red, green, and blue channel levels of the
3
+
acetylated derivative 3 were tested. The signaling speed for Tl of
rhodamine 6G-based probe 1 was faster than that of rhodamine
À1
B-based probe 2 (pseudo first-order rate constant: 0.24 min for
À1
46
compound 1 and 0.19 min for compound 2) (Fig. S1 and S2,
ESI†); this observation is similar to the previous report for the
3
3
3+
determination of hypochlorous acid. Furthermore, the Tl
3+
images from the fluorescence. Finally, Tl calibration curve was
obtained by plotting the changes in the green channel level. The
green channel level showed the most distinct signal variation than
the levels of the red and blue channels.
signaling contrast of probe 1 was considerably more pronounced
than that of probe 2 (Fig. S3, ESI†). Meanwhile, acetylated
derivative 3 did not reveal any noticeable responses, which
implies the importance of the unfunctionalized hydroxamic acid
3
+
group of the probe in the Tl signaling process (Fig. S4, ESI†).
3
+
We also investigated the pH-dependency of the Tl signaling of
3
. Results and discussion
compound 3 and found that the acetylated derivative showed no
3+
The Tl -selective reaction-based probe was designed considering meaningful fluorescence changes in the presence and absence of
the fact that hydroxamic acid function is smoothly transformed Tl ions (Fig. S5, ESI†). Therefore, all the signaling experiments
into carboxylic acid by common oxidants. We incorporated were performed with rhodamine 6G-based hydroxamate probe 1.
hydroxamic acid as a signaling switch into the rhodamine dye,
3
+
33
3
+
To obtain optimal signaling conditions for the Tl analysis,
expecting that the transformation could induce the conversion of we systematically optimized the pH, solvent, and composition of
the ring-closed hydroxamate form of the probe to ring-opened the analytical procedure. Fig. S6 (ESI†) shows the pH profile
rhodamine dye, which would revive the dye’s characteristic between the pH of 4.2 and 7.0 obtained from the fluorescence
colorimetric and fluorescence properties. Another feature of results. The pH-profile of the thallium signaling indicated that
the designed probe is that the hydroxamic acid ligating subunit the response was strongly pH-dependent and progressively
3
+
14
is capable of forming a stable complex with Tl ions, which diminished from pH 4.1 to 5.0, then remained relatively constant
would act favorably for promoting the interaction with the probe up to pH 7.0. Under strongly acidic conditions, the hydroxamate
for the expected hydrolysis reaction. As described earlier, the basic function of the probe is likely to convert into a ring-opened form,
framework of rhodamine–hydroxamate 2 has been previously used which resulted in undesirable background colorimetric and
3
+
for the analysis of oxidizing agents (hypochlorous acid and IBX) fluorescent responses. Meanwhile, in basic solutions, Tl is
3
3–35
47
and nerve gas agents.
these species is not a problem for the analysis of Tl ions in
typical applications because IBX and nerve gas agents are not spectrum exclusively toward Tl ions among the tested common
2 3
We believe that the response toward unstable and is known to be converted into an oxide, Tl O .
3
+
Probe 1 exhibited a noticeable change in the fluorescence
3
+
3
+
common targets and the use of these relevant species do not metal ions (Fig. 1). Treatment with Tl significantly increased
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1
Fig. 2 Partial H NMR spectra of 1, purified signaling product, and refer-
ence compound 4. The middle spectrum was acquired after purifying the
product of the signaling process. [1] = [4] = 5.0 Â 10À3 M in DMSO-d
Fig. 1 Changes in fluorescence enhancement (I/I
where ions of common metals are present. Insets: (middle) fluorescence
0
) of probe 1 at 551 nm
6
.
spectra of 1 with metal ions present, (right) photograph of probe in the presence
3
+
À6
and absence of Ti using a UV lamp for illumination. [1] = 5.0 Â 10 M,
3
+
n+
À3
[M
] = 1.5 Â 10 M in a solution of acetate buffer (pH 4.2, 10 mM) signaling speed for IBX was similar to that of Tl ions (Fig. S11,
containing 30% (v/v) DMSO. lex = 527 nm.
ESI†). However, as previously described, we believe that the
response from IBX is not so relevant for the analysis of Tl ions
in routine chemical applications. The undesirable response
from hypochlorous acid, which was observed in aqueous acet-
onitrile and THF solution, was successfully suppressed,
3
+
4
8
the fluorescence intensity of the probe at 551 nm. The increase
was close to 60-fold. Simultaneously, there was a color change in
the solution to fluorescent greenish-yellow from dark when
illuminated with a UV lamp (lex = 365 nm). Fig. S7 (ESI†) shows
that inconsequential results were also observed for most of the
anions tested.
employing the HOCl scavenging effect of DMSO (Fig. S12,
24,49
ESI†).
After a preliminary survey using varying compositions
of DMSO in acetate buffer solution, we found that 30% DMSO
solution is the optimal condition in terms of the selectivity and
Oxidative hydrolysis of the hydroxamate component to a car-
3+
signal contrast of the probe toward Tl ions.
3+
boxylic acid resulted in the signaling of Tl by probe 1 (Scheme 2).
The conversion was preliminarily confirmed by TLC (Fig. S8, ESI†).
For the acquisition of more positive evidence concerning the
postulated conversion, the product from the Tl signaling was
purified using a column chromatogram with silica gel, solvent:
OH = 9 : 1, v/v. There was a close similarity between
the H NMR spectral data of the reference compound 4 and the
purified product (Fig. 2). This is further evidenced by a relevant
peak of the signaling product at m/z = 415.2018 (calculated for
] m/z = 415.2016) (Fig. S9, ESI†).
The probe’s response to other commonly used oxidants were
measured since the functional group of hydroxamic acid can be
hydrolyzed when oxidative conditions are present. Most of the
tested oxidants, except for IBX, did not induce any measurable
changes in the fluorescence spectrum (Fig. S10, ESI†). The
3+
Next, the effect of foreign ions on Tl signaling was substan-
tiated to test the practical applicability of 1. In general, the
presence of ions of common metals is inconsequential to the
Tl signaling activity of the probe as seen in the slight variation in
at 551 nm of 0.86
for Cd ) and 1.15 (for Fe ) (Fig. 3). There was no significant
interference from the anions with a limited variation for the
Anion+Tl(III
) )
/ITl(III between 0.91 (for F ) and 1.08 (for Br ) (Fig. S13,
ESI†). We further confirmed that there is no significant anion-
dependency of Tl signaling properties (Fig. S14, ESI†) by the
experiments using nitrate or acetate salt of Tl ions. On the other
hand, due to the redox-active properties of the iodide ion, it was
not tested. Tl ions are standardized routinely relying on the
3+
3+
the fluorescence intensity ratio IMetal+Tl(III
)
/ITl(III
)
CH
2
Cl
2
:CH
3
2+
3+
(
1
À
À
I
+
[C
26
H
27
N
2
O
3
3+
3+
3+
41
redox reaction with iodide through iodometric titration.
3+
The quantitative analytical profile of the probe for Tl signal-
3
+
response induced by IBX surpassed that of Tl ions and the
ing was elucidated by measuring concentration-dependent
fluorescence changes. The intensity of fluorescence at 551 nm
increased proportionally with the increase in thallium ions
(
Fig. S15, ESI†). Based on these results, the linear correlation
2
À5
3+
(
R = 0.9821) up to 2.0 Â 10 M Tl ions of the analysis was
acquired. The limit of detection for thallium ions of the probe was
À7
found to be 2.9 Â 10 M after estimation using the IUPAC
44
3+
recommendation 3sbl/m. In addition, signaling of Tl with the
probe was fast and completed within 5 minutes under the
employed conditions (Fig. S1a, ESI†). Meanwhile, the probe itself
did not exhibit any measurable changes in fluorescence over
3
hours after sample preparation.
Probe 1 also showed prominent colorimetric signaling beha-
3
+
vior toward Tl ions, as illustrated by the results of UV-vis
measurements. Under the same optimal conditions of pH 4.2
3+
Scheme 2 Signaling of Tl ions by oxidative hydrolysis of probe 1.
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3
+
Fig. 3 Changes in the fluorescence intensity ratio (IMetal+Tl(III
)
/ITl(III
)
) of Tl
Fig. 5 Fluctuations in the red, green, and blue color channel level of
probe 1 when the concentration of thallium ions is varied. Inset: Picture of
solutions for thallium ion signaling. [1] = 5.0 Â 10 M, [Tl ] = 0–10 mM in
acetate buffer solution (pH 4.2, 10 mM) containing 30% (v/v) DMSO. A UV
lamp (lex = 365 nm) was used for illumination.
signaling by probe 1 at 551 nm in the presence of common metal ions under
À6
3+
n+
À3
À6
3+
competitive conditions. [1] = 5.0 Â 10 M, [Tl ] = [M ] = 1.5 Â 10
M in acetate buffer solution (pH 4.2, 10 mM) containing 30% (v/v) DMSO.
ex = 527 nm.
l
acetate-buffered solution containing 30% DMSO, probe 1 showed analysis software (RGB Grabber, Shunamicode). The values for the
no measurable absorption bands above 400 nm. A significant red, green, and blue channels of the image were plotted against
enhancement in absorbance at 527 nm was observed with thallium the concentration of thallium. The calibration curves were not
2
ions alone following interactions with different metal ions (Fig. 4), perfect (R = 0.9656, 0.9786, and 0.9488 for the plots using the red,
oxidants apart from IBX (Fig. S16, ESI†), and anions (Fig. S17, green, and blue channels of the image, respectively) owing to the
3+
ESI†). There was a concurrent color change of the solution to pink slight curvature of the plots (Fig. 5). We found that Tl levels
À6
from colorless. The presence of ions of common metals did down to 5.0 Â 10 M in synthetic urine could be discerned simply
3
+
not affect the signaling of Tl ions (Fig. S18, ESI†), and anions by obtaining a smartphone image. Concerning the IUPAC recom-
(
Fig. S19, ESI†) as a background. These outcomes indicate the mendation (3s /m), the detection limit of the probe to determine
bl
possibility of colorimetric analysis of thallium ions in the thallium ions was assessed using the plot’s green channel value.
À7
À1
routine physiological and chemical analytes using probe 1.
The levels of thallium ions in synthetic urine were determined sensitive enough for the determination of Tl in normal urine
The obtained detection limit (2.9 Â 10 M, 57 mg L ) was not
3+
À8
À1
as a practical application of the probe. Urinary thallium levels, samples (1.32 Â 10 M, 2.6 mg L ). However, we believe that the
along with hair thallium levels, are essential parameters for the present analytical method could be used for preliminary screening
2
1,50
diagnosis of thallium exposure and poisoning.
solutions
Synthetic urine of elevated thallium levels in acute thallium poisoning by a simple
with varying concentrations of Tl were treated with urine test. Recent toxicology research reported that the median
the probe solution under the same signaling conditions, and the urinary thallium level in acute poisoning cases was 1959 mg L
42,43
3+
À1
À6
À1
À6
developed responses were captured using a smartphone. The (8.10 Â 10 M) in a range of 452–2909 mg L (1.87 Â 10 –1.20 Â
À5
51
3+
fluorescence images of the solutions were analyzed using color 10 M). We also confirmed that the Tl calibration curve and
the detection limit of the probe obtained from the smartphone
image were quite similar to the results obtained by independent
fluorescence measurements (Fig. S20, ESI†). As mentioned in the
introduction, the analysis of the urinary thallium levels is now
routinely carried out using procedurally complicated heavy instru-
ments such as an ICP-MS and atomic absorption spectrometer
10
with complicated procedures. By relying on the present method,
elevated urinary thallium levels in accidental acute poisoning cases
could be rapidly assessed from images obtained using a readily
available smartphone.
4. Conclusions
A simple, small molecule-based probe was developed for the
selective and sensitive detection of toxic thallium ions. The basis
of signaling was oxidative hydrolysis, stimulated by thallium ions,
of the hydroxamate moiety of the probe based on rhodamine
fluorophore to restore the fluorescence and colorimetric activity of
0
Fig. 4 Changes in absorbance enhancement (A/A ) of probe 1 at 527 nm
when the ions of common metals are present. Insets: (middle) absorption
spectra of 1 when metal ions are present, (right) photograph of the probe in the
À6
n+
À3
presence and absence of thallium ions. [1] = 5.0 Â 10 M, [M ] = 1.5 Â 10
M
in acetate buffer solution (pH 4.2, 10 mM) containing 30% (v/v) DMSO.
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the parent dye. The presence of ions of common metals, oxidants, 17 B. Krasnod ˛e bska-Ostr ˛e ga, M. Sadowska, K. Piotrowska and
or anions apart from iodide ions that are redox-active, did not
M. Wojda, Talanta, 2013, 112, 73–79.
influence thallium ion-selective signaling. Smartphone images 18 U. Karlsson, A. Duker and S. Karlsson, J. Environ. Sci. Health,
were used to successfully visualize the levels of thallium ions in
synthetic urine with a detection limit of 290 nM. The method
Part A: Toxic/Hazard. Subst. Environ. Eng., 2006, 41,
1155–1167.
developed through this research can be used for the early diagnosis 19 B. Rezaei, S. Meghdadi and N. Majidi, Spectrochim. Acta, Part
of elevated levels of thallium in urine in cases of acute poisoning.
A, 2007, 67, 92–97.
2
2
2
0 H. D. Revanasiddappa and T. N. K. Kumar, Anal. Sci., 2002,
18, 1131–1135.
Conflicts of interest
1 P. Nagaraja, N. G. S. Al-Tayar, A. Shivakumar, A. K. Shresta
and A. K. Gowda, J. Mex. Chem. Soc., 2009, 53, 201–208.
2 S. Ge, P. Dai, J. Yu, Y. Zhu, J. Huang, C. Zhang, L. Ge and
F. Wan, Int. J. Environ. Anal. Chem., 2010, 90, 1139–1147.
There are no conflicts of interest to declare.
Acknowledgements
23 A. A. Ensafi and B. Rezaei, Microchem. J., 1998, 60, 75–83.
2
2
4 Y. J. Lee, M. G. Choi, J. H. Yoo, T. J. Park, S. Ahn and
S.-K. Chang, J. Photochem. Photobiol., A, 2020, 394, 112471.
5 B. Bodenant, T. Weil, M. Businelli-Pourcel, F. Fages,
B. Barbe, I. Pianet and M. Laguerre, J. Org. Chem., 1999,
This study was supported by the Chung-Ang University Research
Scholarship Grants in 2019 (JHY).
6
4, 7034–7039.
Notes and references
2
6 M. Y. Chae and A. W. Czarnik, J. Fluoresc., 1992, 2, 225–229.
1
L. Manzo and E. Sabbioni, Thallium, in Handbook on 27 B. Bodenant, F. Fages and M. H. Delville, J. Am. Chem. Soc.,
Toxicity of Inorganic Compounds, ed. H. G. Seiler, H. Sigel
and A. Sigel, Marcel Dekker, New York, 1988.
L. Ralph and M. R. Twiss, Bull. Environ. Contam. Toxicol.,
1998, 120, 7511–7519.
28 F. Frrgl, Spot Tests in Organic Analysis, Elsevier, Amsterdam,
7th edn, 1966, p. 214.
2
3
2
002, 68, 261–268.
29 R. E. Buckles and C. J. Thelen, Anal. Chem., 1950, 22,
676–678.
EPA Effluent Guidelines, Toxic and Priority Pollutants
Under the Clean Water Act, http://water.epa.gov/scitech/ 30 E. Gagliardi and H. Raber, Mon. Chem., 1962, 93, 360–368.
methods/cwa/pollutants.cfm.
H. Micke and H. U. Wolf, Thallium and Thallium Com-
31 G. H. Cleland and D. W. Knight, J. Chem. Educ., 1970,
47, 781.
4
5
pounds, in Ullmann’s Encyclopedia of Industrial Chemistry, 32 A. S. Saljooghi, M. Babaie, F. D. Mendi, M. Zahmati and
Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 2011.
Z. S. Saljooghi, Toxicol. Ind. Health, 2016, 32, 83–88.
A. Mckillop, Applications of Thallium(III) Nitrate (TTN) to 33 Y. K. Yang, H. J. Cho, J. Lee, I. Shin and J. Tae, Org. Lett.,
Organic Synthesis, in Organic Synthesis, ed. A. Bruylants,
2009, 11, 859–861.
L. Ghosez and H. G. Viehe, Butterworth-Heinemann, 34 T. Sun, J. O. Moon, M. G. Choi, Y. Cho, S. W. Ham and
Oxford, 1975.
S.-K. Chang, Sens. Actuators, B, 2013, 182, 755–760.
T. Viraraghavan and A. Srinivasan, Thallium: Environmental 35 S. Han, Z. Xue, Z. Wang and T. B. Wen, Chem. Commun.,
6
Pollution and Health Effects, in Encyclopedia of Environmental
Health, Elsevier Inc., Amsterdam, 2012.
2010, 46, 8413–8415.
36 S. Bae and J. Tae, Tetrahedron Lett., 2007, 48, 5389–5392.
7
8
9
A. N. Sharma, L. S. Nelson and R. S. Hoffman, Am. J. Forensic 37 Y. A. Jeong, J. Choi and S.-K. Chang, Tetrahedron Lett., 2015,
Med. Pathol., 2004, 25, 156–158.
56, 4919–4922.
T. W. Sun, Q. Y. Xu, X. J. Zhang, Q. Wu, Z. S. Liu and 38 H. Kim, K. S. Moon, S. Shim and J. Tae, Chem. – Asian J.,
Q. C. Kan, Clin. Toxicol., 2012, 50, 65–69.
2011, 6, 1987–1991.
G. Kazantzis, Environ. Geochem. Health, 2000, 22, 275–280.
0 G. Zhao, M. Ding, B. Zhang, W. Lv, H. Yin, L. Zhang, Z. Ying
and Q. Zhang, Eur. Neurol., 2008, 60, 292–297.
1 M. M. Hassanien, Kh. S. Abou-El-Sherbini and
G. A. E. Mostafa, Talanta, 2003, 59, 383–392.
39 H. Kim, S. Lee, J. Lee and J. Tae, Org. Lett., 2010, 12,
5342–5345.
40 A. A. Tahir, H. Ullah, P. Sudhagar, M. A. M. Teridi,
A. Devadoss and S. Sundaram, Chem. Rec., 2016, 16, 124–140.
41 P. D. Sharma and Y. K. Gupta, Talanta, 1973, 20, 903–905.
1
1
1
1
2 D. Zendelovska and T. Stafflov, Anal. Sci., 2001, 17, 425–428. 42 K. Tuantet, M. Janssen, H. Temmink, G. Zeeman,
3 A. F. Silva, D. L. G. Borges, B. Welz, M. G. R. Vale,
M. M. Silva, A. Klassen and U. Heitman, Spectrochim. Acta,
Part B, 2004, 59, 841–846.
R. H. Wijffels and C. J. N. Buisman, J. Appl. Phycol., 2014,
26, 287–297.
43 S. K. Lee, M. G. Choi, J. Choi and S.-K. Chang, Sens.
Actuators, B, 2015, 207, 303–307.
1
1
4 Y. K. Agrawal and V. J. Bhatt, Analyst, 1986, 111, 761–765.
5 A. S. Amin, A. A. M. El-Sharjawy and M. A. Kassem, Spectrochim. 44 D. C. Harris, in Quantitative Chemical Analysis, W.H. Freeman
Acta, Part A, 2013, 110, 262–268.
and Company, New York, 8th edn, 2010, pp. 103–105.
6 D. Mihajlovic and T. Stafilov, X-Ray Spectrom., 1998, 27, 45 S. Y. Park, M. G. Choi, D. S. Lim and S.-K. Chang, Dyes Pigm.,
1
397–400.
2019, 164, 14–19.
608 | New J. Chem., 2021, 45, 603--609
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021

View Article Online
NJC
Paper
4
4
4
6 (a) L. Yuan, W. Lin and Y. Yang, Chem. Commun., 2011, 47, 49 (a) F. C. Lopez, A. Shankar, M. Thompson, B. Shealy, D. Locklear,
6
275–6277; (b) C. Liu, H. Wu, Z. Wang, C. Shao, B. Zhu and
T. Rawalpally, T. Cleary and C. Gagliardi, Org. Process Res. Dev.,
2005, 9, 1003–1008; (b) L. M. Kabeya, M. F. Andrade, F. Piatesi,
A. E. C. S. Azzolini, A. C. M. Polizello and Y. M. Lucisano-Vali,
Anal. Biochem., 2013, 437, 130–132.
X. Zhang, Chem. Commun., 2014, 50, 6013–6016.
7 J. A. Switzer, Electrodeposition of superlattices and multi-
layers, in Electrochemistry of Nanomaterials, ed. G. Hodes,
WILEY-VCH, Verlag GmbH., Weinheim, 2001, p. 82.
8 (a) P. J. Stang and V. V. Zhdankin, Chem. Rev., 1996, 96,
50 A. Brockhaus, R. Dolgner, U. Ewers, U. Kr ¨a mer, H. Soddemann
and H. Wiegand, Int. Arch. Occup. Environ. Health, 1981, 48,
375–389.
1123–1178; (b) A. Varvoglis, Hypervalent Iodine in Organic
Synthesis, Academic Press, London, 1997; (c) A. Varvoglis, 51 F. A. Hammouri, G. Darwazeh, A. Said and R. A. Ghosh,
Tetrahedron, 1997, 53, 1179–1255. J. Med. Toxicol., 2011, 7, 306–311.
This journal is ©The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2021
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