Synthesis and characterization of a novel fluorescent and colorimetric probe for the detection of mercury (II) even in the presence of relevant biothiols

Article abstract of DOI:10.1016/j.tetlet.2015.09.001

We present here a novel probe, coumarin 3-azomethine derivative (AGB), which can detect selectively mercuric ions (Hg²⁺) via a hydrolysis reaction promoted by these ions. Interestingly, the probe can be used to assess the response to Hg²⁺ even in the presence of the most important biothiols-glutathione and cysteine - and could be used in the Hg²⁺ - imaging in living cells.

Full text of DOI:10.1016/j.tetlet.2015.09.001

Accepted Manuscript
Synthesis and characterization of a novel fluorescent and colorimetric probe for
the detection of mercury (II) even in the presence of relevant biothiols
Olimpo García-Beltrán, Alejandra Rodríguez, Ariel Trujillo, Alvaro Cañete,
Pabla Aguirre, Sebastián Gallego-Quintero, Marco T. Nuñez, Margarita E.
Aliaga
PII:
S0040-4039(15)30047-2
DOI:
http://dx.doi.org/10.1016/j.tetlet.2015.09.001
TETL 46673
Reference:
To appear in:
Tetrahedron Letters
Received Date:
Revised Date:
Accepted Date:
9 July 2015
20 August 2015
2 September 2015
Please cite this article as: García-Beltrán, O., Rodríguez, A., Trujillo, A., Cañete, A., Aguirre, P., Gallego-Quintero,
S., Nuñez, M.T., Aliaga, M.E., Synthesis and characterization of a novel fluorescent and colorimetric probe for the
detection of mercury (II) even in the presence of relevant biothiols, Tetrahedron Letters (2015), doi: http://
dx.doi.org/10.1016/j.tetlet.2015.09.001
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1
Tetrahedron Letters
Synthesis and characterization of a novel fluorescent and colorimetric probe for the
detection of mercury (II) even in the presence of relevant biothiols
a*
b
b
b
c
Olimpo García-Beltrán, Alejandra Rodríguez, Ariel Trujillo, Alvaro Cañete, Pabla Aguirre, Sebastián
a
c
b
Gallego-Quintero, Marco T. Nuñez and Margarita E. Aliaga.
a
Facultad de Ciencias Naturales y Matemáticas, Universidad de Ibagué, Carrera 22 Calle 67, Ibagué 730001, Colombia.
Facultad de Química, Pontificia Universidad Católica de Chile, Casilla 306,Santiago 6094411, Chile.
Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago, Chile.
b
c
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
We present here a novel probe, coumarin 3-azomethine derivative (AGB), which can
2+
detect selectively mercuric ions (Hg ) via a hydrolysis reaction promoted by these ions.
2
+
Interestingly, the probe can be used to assess the response to Hg even in presence of the
2+
most important biothiols -glutathione and cysteine- and could be used in the Hg -
imaging in living cells.
Available online
2
012 Elsevier Ltd. All rights reserved.
Keywords:
2
+
Hg -detection
Mercury bound biothiols
Colorimetric/Fluorescent probe
Coumarin 3-azomethine derivative
Hydrolysis reaction
—
——
*
Corresponding author. Tel.: +57-8-270 9444; fax: +57-8-2709443; e-mail: jose.garcia@unibague.edu.co (O. García-Beltrán),
mealiaga@uc.cl (M.E. Aliaga).

2
Tetrahedron
Mercury is a heavy transition metal that generally possesses
Once the structure of the compound AGB was confirmed, some
photophysical properties of AGB were assessed. Regarding the
absorption spectrum of AGB it depicts two bands with maxima at
~240 nm and ~350 nm (Fig. 1A). These bands might be mainly
associated with π→π* transitions and an overlap of π→π* with
n→π* transitions, according to what is reported for similar
three distinct oxidation states 0, +1 and +2, although quantum
chemical predictions have also suggested the existence of mercury in
1
2+
its oxidation state +4. Among these, the mercuric state Hg , is
considered one of the most toxic and dangerous form due to its very
high affinity for sulfhydryl groups. In this context, the interaction
between mercuric ions and glutathione (GSH) leads to favorable
generation of different mercury containing GSH-complexes. For
18,19
compounds.
The maximum of the absorption band of AGB at
-1
-1
350 nm exhibits an extinction coefficient (ε) of 16021 M cm (Fig.
S4, Supporting Information).
2+
2-4
2
example in the case of the Hg -[GSH] complex a high affinity
between Hg(II) and GSH, with stability constant (log  ≥20), has
When excited at 350 nm, the emission spectrum of AGB exhibits a
maximum at 460 nm, as shown in insert to Fig. 1B, (in black color).
However, the emission intensity associated with the compound AGB
is low (quantum yield of 0.01), probably attributed to a decay
process of the C=N bond cis-trans isomerization, as mentioned
3
been reported. Additionally, considering that the intracellular
5
concentration of GSH is high (0.5-10 mM) the presence of free
mercury ions, in biologically relevant conditions, would be very low
and thus the metal would be predominantly involved in sulfur-
containing complexes. In consequence, the latter would limit the
detection of free mercuric ions in such conditions.
14
above.
6
-8
9
Different probes based on rhodamine, coumarin, and squaraine
10
11-13
derivatives, as well as other chromophores,
have been
developed to detect the presence of free (or labile) mercury (II) ions.
Nonetheless, currently few reports discuss how to avoid the potential
interference from sulfur-rich environments (namely in the presence
2+ 12,13a
of GSH and cysteine) in the detection of Hg .
On the other hand, it is known that chromophores containing
azomethine groups (also called Schiff bases) have been used as
sensors of metals, mainly by taking advantage of the suppression of
1
4,15
C=N isomerization due to the binding with the metal.
context, several studies
In this
14,15
have indicated that as a consequence of
this binding a restriction of such isomerization occurs and a
significant fluorescence enhancement is observed.
Nonetheless, probes containing azomethine group can also act as
Figure 1. (A) Absorption spectra of AGB (5-100 μM) in a DMSO:H
2
O (1:99,
13,16,17
chemodosimeters via hydrolysis reaction promoted by metals.
In this line, only few probes have been developed for selectively
v/v). (B) Absorption spectra of AGB (20 μM) solution in the absence (black
2
+
line) or in the presence of 10 eq. Hg (red line), after 5 min of incubation at
25ºC; insert represents the emission spectra of AGB (5 μM) in a DMSO:H
(1:99, v/v) solution in the absence (black line) or in the presence of 10 eq.
2+
13
detect Hg ions via hydrolytic pathway of the azomethine group.
2
O
Prompted by the latter, we present here a novel probe based on a
2
+
coumarin-3-azomethine derivative linked to O-(4-formylphenyl)
Hg (red line).
2+
dimethylcarbamothioate, which could be useful for Hg detection
even in the presence of biologically relevant thiols.
Upon the addition of mercuric ions to a solution containing AGB, we
found that the absorption band at 350 nm it undergoes a small
hypsochromic shift (15nm) and at least two zones of the spectrum
suffer spectroscopic changes, as shown in Figures 1(B). On the other
hand, when excited at 350 nm, a fluorescence intensity enhancement
was observed at 460 nm (Insert Fig. 1B). These changes in the UV-
Vis and emission spectra could be associated with the formation of
new species after the interaction between mercuric ions and AGB.
The new probe, (E)-O-(4-(((7-hydroxy-2-oxo-2H-chromen-3-
yl)imino)methine)phenyl)dimethylcarbamothioate
(AGB)
was
prepared via conventional four-step synthesis from commercial
precursors. The first step involves a Vilsmeier-Haack formylation of
resorcinol to obtain 2,4-dihydroxybenzaldehyde, which is
subsequently condensed with N-acetylglycine (by a Knoevenagel
reaction) and hydrolyzed in situ to afford 3-amino-7-
hydroxycoumarin. The final step is the condensation of 3-amino-7-
hydroxycoumarin with O-(4-formylphenyl) dimethylcarbamothioate
to yield the final product AGB (Scheme 1), which was characterized
2+
To ensure that AGB only interacts with Hg , we examined the
effects of various metal ions on the spectral features of AGB.
Variation of the absorption maximum spectra of AGB upon addition
1
13
+
+
+
2+
2+
2+
by H-NMR, C-NMR spectroscopy (Figs. S1 & S2, Supporting
Information) and by high-resolution mass spectrometry (HRMS)
of different metal cations including Li , Na , K , Mg , Ca , Ba ,
3+
2+
2+
3+
+
2+
2+
2+
2+
2+
Al , Cu , Cd , Fe , Ag , Mn , Pb , Zn , Ni and Co is shown
in Fig. 3. The absorption maximum shows no obvious changes upon
the addition of such tested metals. In addition, selectivity
experiments were also carried out using fluorescence spectroscopy
and we found no interferences of other ions on the response of AGB
(
Fig. S3, Supporting Information).
(
not shown).
Scheme 1. Synthetic route to AGB. Reagents and conditions: a) POCl
acetonitrile, 0-5 °C, 2 h; b) acetylglycine, acetic anhydride, anhydrous sodium
acetate, reflux 4 h; c) 2:1 HCl/H O reflux, 2 h; d) O-(4-formylphenyl)
dimethylcarbamothioate, EtOH, reflux, 4 h.
3
, DMF,
2

3
Figure 4. (A) Time dependent UV-Vis spectra of AGB (20 M) upon
addition of HgCl
2
0 f
(200 M) in 20 mM PBS buffer, pH 6.0; t and t represent
2
+
Figure 2. Selectivity of the AGB probe (15 μM) toward Hg ions (200 μM)
initial and final time (100 s), respectively. (B) Kinetic profile for the
interaction between AGB (20 M) and Hg (600 M), at 25ºC.
2
+
3+
2+
2+
2+
2+
2+
in the presence of other metal ions: Hg , Fe , Fe , Co , Cu , Ca , Zn ,
2+
2
+
2+
2+
2+
2+
Mn , Mg , Ni , Pb or Cd (200 μM). The white bar represents the AGB
probe alone and the light grey bars represent solutions containing AGB plus
different metal ions, after 5 min of incubation at 25ºC.
In this context, figure 5 shows the variation of the pseudo-first-order
rate constants (kobsd) for the proposed decomposition reaction of
AGB with pH values (between 5.0 and 7.0, data from Table S1).
Once assess the selectivity of our probe, we determine the limit of
detection (LOD) of AGB toward mercuric ions. With this aim, we
carried out titration experiments of AGB by the incremental addition
of Hg(II) ions (from 20 to 200 µM). The plot in Fig. 3 shows a linear
0.100
2
-1
pH=5.0
behavior (r = 0.987, k = -726.2 au M ) with a standard deviation of
-5
pH5.5
σ = 0.0054. The LOD calculated (3σ/k) gave a result of 2.2 x 10 M
0.075
-6
(
as colorimetric probe) and 4.5 x 10 M (as fluorescent probe).
pH=6.2
These values suggest the use of AGB as colorimetric or fluorescent
0
0
0
.050
.025
.000
2+
probe for Hg
applications.
either in environmental and/or biological
pH=7.0
0.0006
0
.0000
0.0002
0.0004
2
+
[
Hg ]/ M
2
+
Figure 5. Plot of kobsd vs. concentration of Hg ions for the interaction of
2
+
AGB with Hg at different pHs values.
We found that the reaction rate strongly increases at low pH values,
whereas at pH > 8 no significant reaction was observed (data not
shown). The latter behavior permits to propose an acid-catalytic
process as the rate-determining step in the decomposition of
coumarin-3-azomethine derivative induced by mercuric ions. Under
our experimental conditions, the reaction stoichiometry between
Figure 3. Plot of absorbance at 370 nm of AGB (20 µM) against
2
+
concentrations of Hg from 20 to 200 µM, in aqueous solution.
2+
Aiming to explore the mechanism of mercury-induced signal
suppression of AGB (Fig. 3), we performed kinetic studies to
evaluate the response of this coumarin-3-azomethine derivative to
AGB and Hg ions was determined to be 2:1 from the Job’s
9b,11d
analysis
(Fig. S5, Supporting Information). This result also
suggests a catalytic participation of mercury in the process.
2+
Hg , under pseudo-first-order reaction conditions, at 25 °C. The
time-dependent response of AGB to mercury ions was monitored by
UV-Vis spectroscopy.
To gain information on the kind of reaction that AGB undergoes in
2+
the presence of Hg , NMR and HRMS analyses were carried out.
As previously mentioned and as shown in Fig. 4(A), after the
addition of mercuric ions to a solution containing AGB, a new
absorption band (near 340 nm) appears as a consequence of the
decrease of the band at 370 nm. This process was completely
finished after 100 s of reaction at pH=6.0 (Fig. 4(B)). In this period
of time, probably a decomposition reaction of AGB promoted by
Figure 6 presents the spectra of AGB (20 mM in part A) and that
resulting from mixing such compound with three equivalents of Hg
ions (part B). This figure shows that once these ions are added, the
Hb proton signal of AGB at 7.8 ppm (Fig. 6(A)) shifts upfield to 6.8
ppm (Fig. 6(B)), accompanied by more subtle changes in the rest of
the aromatic region of the spectrum.
2+
2+
Hg is occurring.
It is important to note that the kinetic profiles clearly indicate the fast
2+
response of our probe to Hg in comparison with other mercury
12,13a
probes.

4
Tetrahedron
13
Regarding C-NMR experiments, we observed that upon addition of
2+
Hg ions to a solution of AGB, the signal at 164 ppm disappears
while a new peak at 193 ppm is formed. The former may be
associated with the corresponding carbon of azomethine fragment
while the latter may correspond to the aldehyde carbon present in the
O-(4-formylphenyl) dimethylcarbamothioate (Fig. 7). This result
corroborates the proposed hydrolysis reaction of AGB promoted by
2
+
Hg .
2+
On the other hand, it is well known that Hg ions are able to induce
8
a desulfurization reaction on a sulfur atom linked to carbon (C=S).
However, this reaction was discarded, at least in our experimental
13
conditions, considering the results obtained from C-NMR (Fig. 7).
These results show that the observed signal at =186.3 ppm,
attributable to C=S present in AGB, was not modified after the
addition of mercuric ions.
The presence of both proposed products of reaction, O-(4-
formylphenyl)
dimethylcarbamothioate
and
3-amino-7-
hydroxycoumarin, is also been supported by HRMS (in positive
mode) studies (Fig. S6, Supporting Information). Molecular ion
1
Figure 6. H NMR spectra of AGB in DMSO-d
6
in the absence (A) and in the
+
+
presence (B) of 3 eq. of HgCl in DMSO-d :D O 9:1.
2
6
2
peaks at m/z 209.0387 [M] and 179.0167 [M+2H)] , respectively, in
2+
the HRMS-ESI spectra of AGB in the presence of Hg strongly
support their formulations.
Concerning the signal of the imine proton Ha, at =8.95 ppm, it
disappears and a typical aldehyde signal arises at =9.95 ppm.
Therefore, the NMR spectrum presented in Figure 6(B) could be
associated with the presence of an amino-hydroxycoumarin and a
benzaldehyde derivative. In consequence we suggest that the
decomposition of AGB corresponds to a hydrolysis reaction where
Considering these results, in particular the formation of 3-amino-7-
hydroxycoumarin, it is easy to explain the hypsochromic shift
observed for the absorption band of AGB from 360 nm to 340 nm
2+
when Hg is added (Fig. 1B). This shift would be a consequence of
the absorption properties of 3-amino-7-hydroxycoumarin, namely an
absorption spectrum centered at 340 nm, which has been recently
the
principal
products
would
be
O-(4-formylphenyl)
dimethylcarbamothioate and 3-amino-7-hydroxycoumarin (see the
structure in spectrum B).
20
reported by us.
It is important to note that, when mercuric ions are added into a
solution containing 3-amino-7-hydroxycoumarin, no changes are
observed in the UV-Vis spectra between 300-450 nm at least during
1 h after mixing (not shown). Thus, the possibility that this product
With the aim to demonstrate the importance of the presence of
mercuric ions in the studied reaction, a control experiment was
1
2+
carried out in the absence of these ions. In this case the H-NMR of
reacts with Hg is discarded.
AGB remained unchanged at least during the time that its reaction
2+
with Hg was ended.
Additionally, taking into account the results of kinetic studies
and product analysis the most probable mechanism is that described
in Scheme 2, where the first step involves the reaction of water with
AGB, which is promoted by mercuric ions. Then in a second step the
intermediate (2) is protonated by the reaction media and finally
occurs the fast decomposition of hemiaminal intermediate (3) of
AGB occurs to yield O-(4-formylphenyl) dimethylcarbamothioate
and 3-amino-7-hydroxycoumarin.
O
N
+
O
N
H
O
S
H
S
Hg2+
K1 H2O
N
O
N
O
Hg2+
HO
O
HO
O
AGB
(2)
k2 [H+]
O
N
H
O
S
1
3
Figure 7. C NMR spectra of AGB in DMSO-d
presence (B) of 3 eq. of HgCl in DMSO-d :D O 9:1.
6
in the absence (A) and
fast
NH2
O
O
S
N
N
O
H
2
6
2
+
Hg2+
H
HO
O
HO
O
(3)
O
2
+
Scheme 2. Proposed mechanism of Hg -induced imine hydrolysis of AGB.
In view that some important sulfhydril containing biomolecules, such
as the aminoacid cysteine (Cys) and the tripeptide glutathione
4
2+
(
GSH), could interact with Hg , we investigated the effect of these
2+
endogenous thiols on the detection of Hg in neutral conditions
HEPES buffer solutions pH 7.0, 20 mM). As shown in Figure 8, the
(

5
2
+
addition of AGB to a solution containing Cys (500 µM) does not
induce change in the fluorescence response in comparison with AGB
Hg in aqueous media. Interestingly, this probe is able to detect
mercuric ions even in the presence of cysteine or glutathione via an
acid-catalyzed hydrolysis process. Most importantly, this probe was
2+
alone. However, when AGB was added to a solution of Hg (200
µM) in the presence of Cys a considerable increase of the
fluorescence intensity was observed (quantum yield near 0.4), which
2+
successfully applied to the imaging of Hg ions in cells.
2+
is very close to the increment induced only by Hg .
Acknowledgments
This work was supported by #14-305-INT Universidad de Ibagué,
FONDECYT Grants #1130062 and Fondequip EQM-120163.
3
2
2
1
50
80
10
40
References and notes
1
2
.
.
Wang, X.; Andrews, L.; Riedel, S.; Kaupp, M. Angew. Chem.,
007, 119, 8523.
2
Rabenstein, D. L. Metal complexes of glutathione and their
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John Wiley & Sons, New York.
7
0
0
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Oram, P. D.; Fang, X.; Fernando, Q.; Letkeman, P.; Letkeman, D.
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Meister, A.; Anderson, M. E. Ann. Rev. Biochem., 1983, 52, 711.
Bera, K.; Das, A.; Nag, M.; Basak, S. Anal. Chem., 2014, 86,
2
740.
2
+
Figure 8. Detection of Hg (200 µM) in the presence of glutathione or
cysteine (500 µM) in HEPES buffer (pH 7.0, 20 mM) by AGB (10 µM).

7
8
.
.
Kumari, N.; Dey, N.; Bhattacharya, S. Analyst, 2014, 139, 2370.
Kim, H. N.; Ren, W. X.; Kim, J. S.; Yoon, J. Chem. Soc. Rev.,
2
exc.= 340 nm and em.=460 nm.
012, 41, 3210 and references therein.
9
.
For some examples, see: (a) Voutsadaki, S.; Tsikalas, G. K.;
Klontzas, E.; Froudakis, G. E.; Katerinopoulos, H. E. Chem.
Commun., 2010, 46, 3292; (b) Lee, H.; Kim, H.-J. Tetrahedron
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T.; Castro, E. A.; Cassels, B. K.; Núñez, M. T.; Aliaga, M. E.
Tetrahedron Lett., 2012, 53, 6598.
A similar result was obtained when GSH was assessed instead of Cys
and when the absorbance at 370 nm was taken into account (Fig. S7,
2+
Supporting Information). This suggests that AGB could detect Hg
in the sulfur rich environment.
1
0. Chen, C.; Wang, R. Y.; Guo, L. Q.; Fu, N. Y.; Dong H. J.; Yuan,
Finally, and taking advantage of the observed changes in the
fluorescence response of AGB in the presence of mercury ions, free
and bound to biothiols, we assessed the AGB probe for in vitro
Y. F. Org. Lett., 2011, 13, 1162.
11. For some examples, see: (a) Kumar, A.; Dubey, M.; Pandey, R.;
Gupta, R. K.; Kumar, A.; Kalita, A. Ch.; Pandey, D. Sh. Inorg.
Chem. 2014, 53, 4944; (b) Li, Q.; Peng, M.; Li, H.; Zhong, Ch.;
Zhang, L.; Cheng, L.; Peng, X.; Wang, Q.; Qin, J.; Li, Z. Org.
Lett., 2012, 14, 2094; (c) Cheng, X.; Li, Q.; Qin, J.; Li, Z. ACS
Applied Materials & Interfaces, 2010, 2, 1066; (d) Lee, H.; Kim,
H.-J. Bull. Korean Chem. Soc. 2011, 32, 3959.
2+
detection of Hg ions in SH-SY5Y neuroblastoma cells. The cell
lines were incubated with AGB (5.0 μM) in culture medium for 30
min at 37 °C; a weak fluorescence of AGB inside the living cells was
observed (Figure 9A). However, when the living cells were
2+
incubated with Hg (10 μM) in the medium for another 30 min at 37
C, the fluorescence in cells was much higher (Figure 9B).
1
2. Du, J.; Fan, J.; Peng, X.; Sun, P.; Wang, J.; Li, H.; Sun, S. Org.
Lett., 2010, 12, 476.
°
1
3. (a) Bhalla, V.; Roopa, N.; Kumar, M.; Sharma, P. R.; Kaur, T.
Dalton Trans., 2013, 42, 15063; (b) Wu, G.; Shi, B.; Hu, B.;
Zhang, Y.; Lin, Q.; Yao, H.; Wei, T. Chin. J. Chem. 2014, 32,
6
37.
1
1
4. Wu, J.-S.; Liu, W.-M.; Zhuang, X.-Q.; Wang, F.; Wang, P.-F.;
Tao, S.-L.; Zhang, X.-H.; Wu, S.-K.; Lee, S.-T. Org. Lett. 2007, 9,
3
3.
5. For some examples, see: (a) Wu, J. S.; Liu, W. M.; Ge, J. C.;
Zhang, H. Y.; Wang, P. F. Chem. Soc. Rev., 2011, 40, 3483; (b)
Ray D.; Bharadwaj, P. K. Inorg. Chem., 2008, 47, 2252; (c) Li, Z.
X.; Yu, M. M.; Zhang, L. F.; Yu, M.; Liu, J. X.; Wei, L. H.;
Zhang, H. Y. Chem. Commun., 2010, 46, 7169; (d)
Chandrasekhar, V.; Bag P.; Pandey, M. D. Tetrahedron, 2009, 65,
9
876; (e) Jung, H. S.; Ko, K. C.; Lee, J. H.; Kim, S. H.; Bhuniya,
S.; Lee, J. Y.; Kim, Y.; Kim, S. J; Kim, J. S. Inorg. Chem., 2010,
9, 8552.
Figure 9. Fluorescence images of SH-SY5Y cells lines. (A) Fluorescence
images of cells incubated with 5 µM of the AGB probe. (B) Fluorescence
4
1
6. Kumar, A.; Dubey, M.; Pandey, R.; Gupta, R. K.; Kumar, A.;
Kalita, A. Ch.; Pandey, D. S. Inorg. Chem. 2014, 53, 4944.
7. Li, N.; Xiang, Y.; Tong, A. Chem. Commun., 2010, 46, 3363.
8. Karapire, C.; Kolancilar, H.; Oyman, Ü.; Icli, S.J. Photochem.
Photobiol. A. 2002, 153, 173.
images of cells upon treatment with AGB (5 μM) and then with HgCl
μM) for 30 min.
2
(10
1
1
The increase in the fluorescence observed in Figure 9 would be a
consequence of the generation of 3-amino-7-hydroxycoumarin by the
19. García-Beltrán, O.; Yañez, O.; Caballero, J.; Galdámez, A.; Mena,
2+
N.; Nuñez, M.T.; Cassels, B.K. European J. Med. Chem. 2014, 76,
Hg -mediated hydrolysis of AGB. Therefore, considering that the
AGB probe is cell permeable and taking into account the above
7
9.
2+
20. García-Beltrán, O.; Cassels, B.K.; Pérez, C.; Mena, N.; Núñez,
results, we proposed that AGB is useful as an intracellular Hg ion
M.T.; Martínez, N.P.; Pavez, P.; Aliaga. M.E. Sensors. 2014, 14,
imaging probe.
1
358.
In conclusion, a 3-azomethine derivative of coumarin dye (AGB)
was synthesized as a selective fluorescent and colorimetric probe for

6
Tetrahedron
Supplementary Material
Supplementary material associated with this article can be
found, in the online version.

Graphical Abstract
Synthesis and characterization of a novel fluorescent and colorimetric probe for the detection of mercury (II)
even in the presence of relevant biothiols
Olimpo García-Beltrán, Alejandra Rodríguez, Ariel Trujillo, Alvaro Cañete, Pabla Aguirre, Sebastian Gallego-Quintero, Marco T. Nuñez
and Margarita E. Aliaga