'Naked-eye' quinoline-based 'reactive' sensor for recognition of Hg2+ ion in aqueous solution

Article abstract of DOI:10.1016/j.bmcl.2014.10.052

A new 'naked-eye' quinoline-based 'reactive' ratiometric fluorescent probe was prepared. The reactive stoichiometry of the probe with Hg²⁺ ion was 2:1. The probe exhibited high selectivity towards Hg²⁺ ion to other metal ions with a

Full text of DOI:10.1016/j.bmcl.2014.10.052

Bioorganic & Medicinal Chemistry Letters 24 (2014) 5373–5376
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
‘
Naked-eye’ quinoline-based ‘reactive’ sensor for recognition of Hg2+
ion in aqueous solution
a
a
a
a
a,b,
⇑
Yanhua Zhang , Yuanyuan Yan , Suying Chen , Zhinan Gao , Hui Xu
a
Research Institute of Pesticidal Design & Synthesis, College of Sciences, Northwest A&F University, Yangling 712100, Shaanxi Province, People’s Republic of China
State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A&F University, Yangling 712100, Shaanxi Province, People’s Republic of China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
A new ‘naked-eye’ quinoline-based ‘reactive’ ratiometric fluorescent probe was prepared. The reactive
stoichiometry of the probe with Hg ion was 2:1. The probe exhibited high selectivity towards Hg
ion to other metal ions with a 410-fold increase in absorbance intensity ratio (A402/A340) in aqueous
solution over a wide-range pH value (2–12), accompanied by a resonance color change from colorless
to pale yellow visible to naked-eye.
Received 2 September 2014
Revised 15 October 2014
Accepted 17 October 2014
Available online 22 October 2014
2+
2+
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Quinoline
Naked-eye
Fluorescence
Sensor
Mercury ion
Reactive probe
Because Hg2+ ion can be bioaccumulated through the food chain
and cause great damage to the nervous system and other organs by
the blood–brain barrier even at very low concentrations, so it is a
very toxic and dangerous element for human beings.1 Therefore,
development of selective and sensitive chemosensors for detection
of Hg2+ ion over other heavy and transition metal (HTM) ions is still
oxybenzaldehyde (2) in the presence of t-BuOK. Finally,
compound 2 reacted with 2-methylquinoline to afford sensor 3,
which was well characterized by H and C NMR spectroscopy
(see Supplementary data).
1
13
As depicted in Figure 1, the spectrum of the free 3 showed a
2+
strong band at 419 nm (excitation = 340 nm). When Hg ion was
2+
highly necessary. Various probes for recognition of Hg ion over
added to the solution of 3, interestingly, an increase of the fluores-
2
other HTM ions have been developed in recent years. Meanwhile,
cence intensity with a red-shift at 521 nm was observed. Whereas
other attractive probes for detection of Hg2 ion based on the
+
other tested metal ions, such as Fe , Ca , Ni , Cu , Ba , Zn
3+
2+
2+
2+
2+
2+
,
3
2+
2+
2+
2+
2+
+
+
+
specific mercury-promoted reaction were also described.
Cd , Co , Pb , Mn , Mg , K , Cs and Ag , showed no clear
enhancement or decrease of the fluorescence intensity.
Recently, some sensors based on quinoline motif as the fluoro-
ꢀ
4
2+ 5
ꢀ 6
2+
phore have been reported for recognition of F , Zn
,
CN , and
To testify whether sensor 3 selectively detected Hg ion due to
2
+ 7
Cd , respectively. In our previous works, the phenanthroimidaz-
ole-based sensor, tetraphenylethylene-based sensor, and naph-
were prepared and showed the
selective and sensitive detection of Hg ion. Therefore, In contin-
uation of our program to develop selective and sensitive chemo-
removing its vinyl group, we further obtained the product 4, which
8
a
8b
2+
was separated from the mixture of 3 reacting with Hg ion
thalimide-based sensors,8
c–e
(Scheme 2, see Supplementary data). Meanwhile, we directly pre-
2+
0
pared 4 by reaction of 2-methylquinoline with 4-hrdroxybenzal-
2+
dehyde as a control for 4. An evidence for the Hg -promoted
2+
1
sensors for detection of Hg ion, and according to the specific
reactivity of the vinyloxy unit to Hg2 ion,9 in this Letter we
prepared a new and simple quinoline-based sensor 3 (Scheme 1).
As described in the Scheme 1, 4-hydroxybenzaldehyde firstly
reacted with 1,2-dibromoethane to give compound 4-(2-bromo-
ethoxy)benzaldehyde (1), which was then converted into 4-vinyl-
hydrolysis reaction was supported by H NMR spectra of 3, 4 and
+
0
1
4 (as the control). As depicted in the partial H NMR spectra of Fig-
ure 2a, the chemical shifts of three protons of ACH@CH of 3 were
4.48, 4.81 and 6.65 ppm, respectively, upon addition of Hg ion,
the signal of ACH@CH protons of 3 was disappeared (Fig. 2b).
Moreover, the H NMR spectra of 4 was the same as that of the
2
2+
2
1
0
0
control one 4 (Fig. 2b and c). Therefore, 4 and 4 are the same
compound (see Scheme 3).
⇑
Corresponding author. Tel./fax: +86 29 87091952.
E-mail address: orgxuhui@nwsuaf.edu.cn (H. Xu).
The absorbance intensity ratio (A402/A340) of sensor 3 in the
presence of Hg , Ca , Ni , Cu , Fe , Ba , Zn , Cd , Co , Pb ,
2
+
2+
2+
2+
3+
2+
2+
2+
2+
2+
http://dx.doi.org/10.1016/j.bmcl.2014.10.052
960-894X/Ó 2014 Elsevier Ltd. All rights reserved.
0

5
374
Y. Zhang et al. / Bioorg. Med. Chem. Lett. 24 (2014) 5373–5376
O
MeCN/K CO3
Br t-BuOK/DMSO
HO
2
Br
+
Br
H
r.t./15 min/41%
reflux/15 h/78%
CHO
O
O
1
quinaldine/acetic anhydride
reflux/18 h/46%
H
N
O
2
3
O
Scheme 1. Synthetic approach for probe 3.
OH
quinaldine/acetic anhydride
reflux/8 h/35%
H
O
N
4'
OH
0
Scheme 3. Preparation of 4 as the control.
Mn2+, Mg2+, K , Cs and Ag+ in CH
+
+
CN–HEPES (0.02 M, pH = 7.0)
3
(
1:1, v/v) were shown in Figure 3. It was noteworthy that only
2
+
when Hg was added to the solution of 3, a drastic increase of
402/A340 from 0.01 to 4.10 was observed. It was accompanied by
A
a resonance color change from colorless to pale yellow visible to
0
naked-eye. The value of A402/A340 of 4 was 4.24, and was used
2
+
the control. Similarly, only when Hg ion was added to the solu-
tion of 3, an increased 106-fold of the fluorescent intensity ratio
(I521/I419) was observed (Fig. S1, see Supplementary data). Reaction
ꢀ
5
2+
ꢀ6
time profile of 3 (1 ꢁ 10 M) towards Hg (5 ꢁ 10 M) in aque-
ous solution was examined in Figure S2 (see Supplementary data),
and the I521/I419 reached the maximum and kept steady after 3 min
ꢀ
5
Figure 1. Variation of the fluorescence intensity of 3 (1 ꢁ 10 M) in CH
3
CN–HEPES
(
0.02 M, pH = 7.0) (1:1, v/v) at 293 K in the presence of 10.0 equiv of the respective
metal ions; the excitation wavelength for Hg was 402 nm, and the others was
40 nm.
2+
2+
2
+
addition of Hg ion. The fluorescent intensity of 3+Hg was
almost a constant value when the pH value was between 2 and
3
1
2 (Fig. S3, see Supplementary data).
The titration reaction curve of probe 3 toward Hg ion was
2
+
2
+
investigated as shown in Figure 4. On addition of Hg ion, the fluo-
rescent intensity of 3 at 419 nm significantly decreased with
simultaneous appearance of a new red-shift emission band at
around 521 nm. The emission shift was as large as 102 nm to a
longer wavelength. The titration reaction curve showed a steady
increase until a plateau was reached when 0.5 equiv of Hg2+ ion
was added. Based on the above results, the proposed sensing
Hg2+
N
N
3
O
4
OH
Scheme 2. Selective cleavage of probe 3 to form 4 in the presence of Hg2+ ion.
9b
mechanism was shown in Scheme 4.
Figure 2. Partial 1H NMR spectra of 3 (a), 4 (b) and 4 (c) in CDCl
0
.
3

Y. Zhang et al. / Bioorg. Med. Chem. Lett. 24 (2014) 5373–5376
5375
ꢀ
5
Figure 3. Absorbance intensity ratio (A402/A340) of 3 (1 ꢁ 10 M) in CH
3
CN–HEPES (0.02 M, pH = 7.0) (7:3, v/v) at 293 K in the presence of 10.0 equiv of the respective metal
ꢀ
5
0
ꢀ5
2+
+
2+
2+
2+
+
+
2+
2+
2+
2+
2+
ions. Inset: Photograph of 3 in the presence of various metal ions. A: 3 (1 ꢁ 10 M); Q: 4 (1 ꢁ 10 M); B–P: 3+Hg , Ag , Ba , Ca , Cd , Co , Cs , Cu , Zn , Pb , Ni , Mg
,
+
3+
ꢀ4
K
and Fe (1 ꢁ 10 M).
To investigate the utility of 3 as an ion-selective fluorescent
2
+
sensor for Hg ion, the cross-contamination experiments were
2
+
ꢀ6
conducted in the presence of Hg (5 ꢁ 10 M) at a concentration
ꢀ5
2+
2+
2+
of 1 ꢁ 10 M mixed with other metal ions such as Ni , Ca , Ba
,
+
3+
2+
2+
2+
2+
+
+
2+
2+
2+
Cs , Fe , Mn , Cd , Zn , Mg , K , Ag , Hg , Co , and Pb at a
ꢀ
5
concentration of 5 ꢁ 10 M, respectively (Fig. 5). Although the
concentration of those competing metal ions was 10-fold of that
2
+
of Hg , they were almost completely unaffected the detection of
2
+
Hg in aqueous solution.
To examine the sensitivity of sensor 3 towards Hg2+, its detec-
tion limit was tested (Fig. S5, see Supplementary data). Hg ion
2+
ꢀ7
could be detected at least down to 1 ꢁ 10 M, and the emission
intensity of 3 at 419 nm decreased linearly with the concentration
2
+
ꢀ7
2
of Hg ion (0–35) ꢁ 10 M (R = 0.9951).
In conclusion, we have prepared a ‘naked-eye’ quinoline-based
‘
reactive’ ratiometric fluorescent probe 3 for selective detection of
2
+
Hg ion in aqueous solution. The reactive stoichiometry of the
probe with Hg ion was 2:1. Probe 3 exhibited high selectivity
towards Hg to other metal ions with a 410-fold increase in
absorbance intensity ratio (A402/A340) in aqueous solution over a
wide-range pH value (2–12). And little interference was
detected for other commonly coexistent metal ions. Moreover,
2
+
2
+
ꢀ
5
Figure 4. Fluorescence titration of
3
(1 ꢁ 10 M) in CH
3
CN–HEPES (0.02 M,
2
+
pH = 7.0) (1:1, v/v) at 293 K with the concentration of Hg ranging from 0 to
ꢁ 10 M; the excitation wavelength was 340 nm.
ꢀ
5
1
Hg(ClO4)2/H2O
HClO4
N
OH
N
HgClO4
-
O
5
3
O
N
Hg(CH CHO)
2
2
4
OH
8
3
/H O
2
N
OH
4
Hg(CH2CHO)ClO4
HgCH CHO
-HClO4
2
7
O
6
4 2
Scheme 4. The possible reaction mechanism of 3 for selective recognition of Hg(ClO ) .

5
376
Y. Zhang et al. / Bioorg. Med. Chem. Lett. 24 (2014) 5373–5376
Figure 5. Results of the competition experiments for 3 (1 ꢁ 10 M) between Hg2+ and other selected metal ions in CH
ꢀ5
CN–HEPES (0.02 M, pH = 7.0) (1:1, v/v) at 293 K; the
3
concentration of Hg2 was 0.5 ꢁ 10 M, and that of each competing metal ions was 5 ꢁ 10 M.
+
ꢀ5
ꢀ5
the Hg2+-promoted selective hydrolysis of a vinyloxy group of
sensor 3 was determined by H NMR spectra.
641; (c) Kim, H. N.; Lee, M. H.; Kim, H. J.; Kim, J. S.; Yoon, J. Chem. Soc. Rev. 2008,
37, 1465; (d) Onyido, I.; Norris, A. R.; Buncel, E. Chem. Rev. 2004, 104, 5911.
(a) Pelossof, G.; Tel-Vered, R.; Liu, X. Q.; Willner, I. Chem. Eur. J. 2011, 17, 8904;
1
2
3
.
.
(
2
b) Kang, T.; Yoo, S. M.; Yoon, I.; Lee, S.; Choo, J.; Lee, S. Y.; Kim, B. Chem. Eur. J.
011, 17, 2211; (c) Kim, H. N.; Nam, S.; Swamy, K. M. K.; Jin, Y.; Chen, X.; Kim, Y.;
Acknowledgments
Kim, S.; Park, S.; Yoon, J. Analyst 2011, 136, 1339.
(a) Lee, M. H.; Lee, S. W.; Kim, S. H.; Kang, C.; Kim, J. S. Org. Lett. 2009, 11, 2101;
(b) Choi, M. G.; Kim, Y. H.; Namgoong, J. E.; Chang, S.-K. Chem. Commun. 2009,
This work was supported by National Natural Science
Foundation of China (No. 31171896), and the Special Funds of
Central Colleges Basic Scientific Research Operating Expenses
3
9
560; (c) Wang, F.; Nam, S.; Guo, Z.; Park, S.; Yoon, J. Sens. Actuators, B 2012, 161,
48; (d) Cheng, X.; Li, S.; Jia, H.; Zhong, A.; Zhong, C.; Feng, J.; Qin, J.; Li, Z. Chem.
Eur. J. 2012, 18, 1691.
(
YQ2013008), Northwest A&F University. We also thank to
4. Basaran, I.; Khansari, M. E.; Pramanik, A.; Wong, B. M.; Hossain, M. A.
Tetrahedron Lett. 2014, 55, 1467.
Prof. H.L. Zhang for the NMR experiments.
5
6
.
.
Dong, Z. P.; Le, X. D.; Zhou, P. P.; Dong, C. X.; Ma, J. T. RSC Adv. 2014, 4, 18270.
Razi, S. S.; Ali, R.; Srivastava, P.; Misra, A. Tetrahedron Lett. 2014, 55, 1052.
Supplementary data
7. Zhou, X. Y.; Li, P. X.; Shi, Z. H.; Tang, X. L.; Chen, C. Y.; Liu, W. S. Inorg. Chem. 2012,
1, 9226.
(a) Guo, Y.; Yan, Y. Y.; Zhi, X. Y.; Yang, C.; Xu, H. Bioorg. Med. Chem. Lett. 2013, 23,
382; (b) Yan, Y.; Che, Z.; Yu, X.; Zhi, X.; Wang, J.; Xu, H. Bioorg. Med. Chem. 2013,
5
8.
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmcl.2014.10.052.
3
21, 508; (c) Yan, Y.; Zhang, Y.; Xu, H. ChemPlusChem 2013, 78, 628; (d) Dai, H. L.;
Xu, H. Bioorg. Med. Chem. Lett. 2011, 21, 5141; (e) Dai, H. L.; Yan, Y. Y.; Guo, Y.;
Fan, L. L.; Che, Z. P.; Xu, H. Chem. Eur. J. 2012, 18, 11188.
References and notes
9.
(a) Ando, S.; Koide, K. J. Am. Chem. Soc. 2011, 133, 2556; (b) Santra, M.; Roy, B.;
Ahn, K. H. Org. Lett. 2011, 13, 3422.
1
.
(a) Kim, H. N.; Ren, W. X.; Kim, J. S.; Yoon, J. Chem. Soc. Rev. 2012, 41, 3210; (b)
Fitzgerald, W. F.; Lamborg, C. H.; Hammerschmidt, C. R. Chem. Rev. 2007, 107,