A facile naphthalene-based fluorescent chemodosimeter for mercury ions in aqueous solution

Article abstract of DOI:10.1039/c4ra16479b

A facile naphthalene-based fluorescence turn-on chemodosimeter, 2-((2-(vinyloxy)naphthalen-1-yl)methylene)-malononitrile (MS1), for rapid, selective and sensitive detection of Hg²⁺ by mercury-promoted hydrolysis of the vinylether group has been reported. The probe displayed a fast response time, and a sensitive fluorescence response (100-fold fluorescence enhancement) to the detection of Hg²⁺ in aqueous solution. This journal is

Full text of DOI:10.1039/c4ra16479b

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: Y. Han, C. Yang,
K. Wu, Y. Chen, B. Zhou and M. Xia, RSC Adv., 2015, DOI: 10.1039/C4RA16479B.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

RSC Advances
Page 1 of 4Journal Name
Dynamic Article Links ►
View Article Online
DOI: 10.1039/C4RA16479B
Cite this: DOI: 10.1039/c0xx00000x
www.rsc.org/xxxxxx
ARTICLE TYPE
A Facile Naphthalene-Based Fluorescent Chemodosimeter for Mercury
Ions in Aqueous Solution
Yifeng Han,* Chengyu Yang, Kai Wu, Yu Chen, Baocheng Zhou and Min Xia*
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX
5
DOI: 10.1039/b000000x
A
facile naphthalene-based fluorescence “turn-on”
chemodosimeter, 2-((2-(vinyloxy)naphthalen-1-yl)methylene)
malononitrile (MS1), for rapid, selective and sensitive
detection of Hg2+ by mercury-promoted hydrolysis of
10 vinylether group has been reported. The probe displayed a
fast response time, and sensitive fluorescence response (100-
fold fluorescence enhancement) to the detection of Hg2+ in
aqueous solution.
Mercury, which is widely distributed in the environment such
15 as the air, soil, and water due to its use in batteries, dental
amalgam, electrical apparatus, and industrial chemicals, is one
of the most ubiquitous and poisonous heavy metals.1 Mercury
ions are not biodegradable, and hence can concentrate through
the food chain in the tissues of fish and marine mammals.
20 Excess mercury accumulation may induce strong damage to
the central nervous system, various cognitive and motor
disorders, and Minamata disease.2 Due to the toxicity of Hg2+,
the determination of mercury in biological and environmental
samples is crucial both to the monitoring of environmental
25 pollution and to the diagnosis of clinical disorders.
In the past several years, considerable efforts have been
made to develop fluorescent chemosensors for Hg2+ based on
the coordination of Hg2+ to heteroatomꢀbased ligands, Hg2+
catalyzed desulfurization, and Hg2+ promoted hydrolysis of
30 the vinyl ether group and βꢀalkynyl ether group.3 However,
most of them still have limitations such as interference from
50
Scheme 1 Hydrolysis of MS1 by mercury ions.
pHꢀdependence may pose detection errors to the results. It is
therefore strongly desirable to develop simple yet specific
fluorescent chemodosimeters for Hg2+ that is immune to pH
turbulence.
55
It is known that Hg2+ catalyzes hydrolysis of vinylether to
form the corresponding hydroxyl group.7 We proposed that
the Hg2+ ion promoted hydrolysis of the vinyl enol ether
group in MS1 would generate the hydroxy intermediate,
which will readily spontaneous cyclize to form a highly
other coexisting metal ions, poor waterꢀsolubility, and 60 fluorescent chemodosimeter (Scheme 1).
laborious synthesis processes expensive chemicals.4
Therefore, for practical applications, it is still desirable to
35 develop simple Hg2+ sensors with good water solubility and
high selectivity and sensitivity.
Our research group is actively engaged in the development
of novel selective and sensitive fluorescent probes for heavy
Compared with the typicallyꢀdeveloped chemosensors,5
fluorescent chemodosimeters, basedꢀon highly specific
chemical reactions between the dosimeters and the analytes,
40 have received much research attention due to their relatively
higher selectivity.6 Recently, Peng, Talukdar, Wu, and Ahn’s
groups have reported fluorescent chemodosimeters based on
“deprotectionꢀcyclization strategy” for the detection of
fluoride ions,6 while the development of chemodosimeters for
45 the specific determination of Hg2+ is drawing increasing
research efforts. However, among the few available Hg2+
chemodosimeters reported,3 most employ the pHꢀsensitive
fluorescein or 7ꢀamino coumarin as the fluorophore and their
Scheme 2 Synthesis of MS1: (a) 1, 2ꢀdibromoethane/K2CO3, acetone,
65 reflux, 3 h, 62%; (b) tꢀBuOK/DMSO, rt, 12 h, 46%; (c) CH2(CN)2 /
piperidine, enthanol, rt, 1h, 48%.
This journal is © The Royal Society of Chemistry [year]
[journal], [year], [vol], 00–00 | 1

RSC Advances
Page 2 of 4
View Article Online
DOI: 10.1039/C4RA16479B
5.0 eq. Hg2+
1.0 eq. Hg2+
0.2 eq. Hg2+
free MS1
0.20
0.15
0.10
0.05
0.00
MS1
MS1+2eq.Hg2+
[Hg2+]
800
600
400
200
0
400
450
500
550
600
650
0
10
20
Wavelength (nm)
Time (min)
Fig. 3 Timeꢀdependent fluorescence intensity changes of MS1 (10 ꢀM)
20 upon addition of various concentration of Hg2+ (0, 0.2, 1.0, 5.0 equiv.
each) in PBS buffer solution (pH 7.4, containing 1% CH3CN) (λex = 395
nm).
Fig. 1 Absorption spectra of MS1 (20 ꢀM) in PBS buffer solution (10
mM, pH 7.4, containing 1% CH3CN) in the presence of different
concentrations of Hg2+ (0ꢀ2.0 equiv.).
5
metal ions.8 Herein, we report the synthesis and properties of
As shown in Scheme 2, MS1 can be readily prepared in
three convenient steps under facile conditions with high yield
a
deprotectionꢀcyclization reaction based fluorescent
chemodosimeter (MS1) that shows high selectivity and
sensitivity for Hg2+.
25 starting
with
commercially
available
2ꢀhydroxyꢀ1ꢀ
naphthaldehyde. The product (MS1) was well characterized
by 1H, 13C NMR, and HRꢀMS (ESI†).
We firstly assessed the UVꢀvis spectroscopic properties of
MS1 in PBS buffer solution (10 mM, pH = 7.4, containing 1%
900
a)
1000
600
[Hg2+]
800
30 CH3CN). MS1 (20 ꢀM) displayed a moderate UVꢀvis
absorption around 538 nm. Upon addition of Hg2+ (0ꢀ2
equiv.), the absorption band at 538 nm decreased and a new
band at 399 nm appeared instantly with an isosbestic point at
439 nm, which is owing to the loss of vinyl enol ether group
35 and the formation of cyclic compound (Fig. 1).
300
600
0
0
2
4
6
8
10
[
Hg2+]/[probe]
400
200
0
As expected, MS1 alone is almost nonꢀfluorescent (λex
=
395 nm, Φ = 0.002, Table S1, ESI†) in neutral aqueous
solution (10 mM PBS buffer, pH 7.4, containing 1% CH3CN),
while the addition of increasing concentrations of Hg2+
40 gradually enhanced the fluorescent signal and ca. 100ꢀfold
increasing was observed when 5.0 equiv. of Hg2+ was added
(Fig. 2a, Table S1, ESI†), which was attributed to the
cleavage of vinyl enol group by mercury ion promoted
hydrolysis reaction and the formation of a highly fluorescent
450
500
550
600
650
Wavelength (nm)
b)
800
MS1+Hg2+
45 cyclic compound (Scheme 1). Moreover,
a blueꢀgreen
600
400
200
0
fluorescent compound 5 have been isolated from MS1ꢀHg2+
system (ESI†), which was agreed well with the proposed
mercury induced deprotectionꢀcyclization mechanism.
Subsequently, the timeꢀdependence of MS1 fluorescence
50 was also evaluated in the presence of different concentration
of Hg2+. The result shows that the fluorescence of all tested
solutions remarkably increased to their maximum value within
the 10 minutes. No changes in fluorescense were detected in
the absence of Hg2+ (Fig. 3).
MS1, MS1+other cations
450
500
550
600
650
Wavelength (nm)
55
Further, the fluorescence titration of MS1 with various
metal ions was conducted to examine the selectivity (Fig.2b).
Much to our delight, the turnꢀon response of MS1 is highly
specific for Hg2+ and no obvious change of fluorescent
emission was observed when it is treated with Co2+, Cr3+,
10 Fig. 2 (a) Fluorescence spectra of MS1 (10 ꢀM) in PBS buffer solution
(pH 7.4, containing 1% CH3CN) in the presence of different
concentrations of Hg2+ (0ꢀ50 ꢀM) (λex = 395 nm). Inset: fluorescence
intensity changes as a function of Hg2+ concentration. (b) Emission
spectra of MS1 (10 ꢀM) in PBS buffer solution (pH 7.4, containing 1%
15 CH3CN) in the presence of various metal ions (λex = 395 nm, 5.0 eq. of
Hg2+, and 10.0 eq. of Co2+, Cr3+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Na+,
Ni2+, Pb2+, Sn4+, Ag+, Ca2+, and Zn2+, respectively).
60 Cu2+, Fe2+, Fe3+, K+, Mg2+, Mn2+, Na+, Ni2+, Pb2+, Sn4+, Ag+,
Ca2+, and Zn2+. It should be mentioned that MS1 still responds
to Hg2+ sensitively even in the presence of other relevant
2
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]

Page 3 of 4
RSC Advances
View Article Online
DOI: 10.1039/C4RA16479B
In conclusion, we have successfully developed a simple
naphthaleneꢀbased fluorescense probe for Hg2+ based on
mercury triggered cleavage reaction under mild conditions.
35 The probe has the unique advantage of easyꢀpreparation, good
water solubility, and excellent selectivity and sensitivity
response towards Hg2+ in aqueous solution. We anticipate that
the experimental results of this study will inspire the future
design of metalꢀion sensors in water for a variety of chemical
40 and biological applications.
800
600
400
200
0
This work was supported by the Zhejiang Provincial
Natural Science Foundation of China (LY14B020016 and
LQ13B020006) and the Program for Innovative Research
45 Team of Zhejiang SciꢀTech University (13060052ꢀY).
Fig. 4 Fluorescence responses of MS1 to various metal ions. Black bars
represent the addition of 5.0 equiv. of Hg2+ and 10.0 equiv. of the other
appropriate metal ion to a 10 ꢀM solution of MS1. Red bars represent the
addition of 5.0 equiv. of Hg2+ to the solutions containing MS1 (10 ꢁM)
and the appropriated metals (10.0 equiv.).
Notes and references
5
Department of Chemistry, The Key Laboratory of Advanced Textile
Materials and Manufacturing Technology, Zhejiang SciꢁTech University,
50 Hangzhou, 310018, China.
Eꢁmail: zstuchem@gmail.com; Tel: +86ꢁ571ꢁ86843550;
Eꢁmail: xiamin@zstu.edu.cn.
competing ions (Fig. 4). Therefore, these results suggest that
MS1 displays high selectivity toward Hg2+ in neutral aqueous
solution.
10
Moreover, the Hg2+ꢀsensing ability of MS1 at a wide range
of pH values was investigated. As depicted in Fig. 5, MS1
alone is inert to pH in the range of 4.0ꢀ11.0. But in the
presence of Hg2+, MS1 have no fluorescence response in the
highly basic environment (pH ≥ 9) due to the reaction rate of
† Electronic Supplementary Information (ESI) available: Experimental
55 details, synthetic details of MS1, additional spectroscopic data, and copies
of NMR spectra. See DOI: 10.1039/b000000x/
1
(a) L. Magos, Met. Ions Biol. Syst., 1997, 34, 321ꢀ370; (b) M. F.
Wolfe, S. Schwarzbach and R. A. Sulaiman, Environ. Toxicol.
Chem., 1998, 17, 146ꢀ160; (c) P. B. Tchounwou, W. K. Ayensu, N.
Ninashvili and D. Sutton, Environ. Toxicol., 2003, 18, 149ꢀ175; (d)
P. Grandjean, P. Weihe, R. F. White and F. Debes, Environ. Res.,
1998, 77, 165ꢀ172.
15 mercury ionꢀpromoted hydrolysis of vinyl enol ether becomes
slow at high pH value.6 However, satisfactory Hg2+ꢀsensing
abilities were exhibited in the range of pH from 4.0 to 8.0,
indicating that MS1 could be used in neutral natural systems,
or a mildly acidic or basic environment.
20 For practical purposes, the detection limit of MS1 for the
analysis of Hg2+ was also an important parameter. The
fluorescence titration curve revealed that the fluorescence
intensity of MS1 at 470 nm increased linearly with the amount
of Hg2+ in the range of 0ꢀ5.0 ꢀM (R2 = 0.994) (Fig. S1, ESI†).
25 Thus, the detection limit of MS1 for Hg2+ was calculated to be
4.31×10ꢀ8 M (Hg content = 8.8 ppb), which reveals the high
sensitivity for the analysis of the mercury ions.
60
65
70
75
80
85
90
95
2
(a) C. R. Baum, Curr. Opin. Pediatr., 1999, 11, 265ꢀ268; (b) E. K.
Silbergeld, I. A. Silva and J. F. Nyland, Toxicol. Appl. Pharmacol.,
2005, 207, S282ꢀS292; (c) R. K. Zalups and S. Ahmad, J. Am. Soc.
Nephrol., 2004, 15, 2023ꢀ2031; (d) Z. Zhang, X. Guo, X. Qian, Z.
Lu and F. Liu, Kidney Int., 2004, 66, 2279ꢀ2282; (e) J. Huang, X.
Ma, B. Liu, L. Cai, Q. Li, Y. Zhang, K. Jiang and S. Yin, J. Lumin.,
2013, 141, 130ꢀ140.
3
(a) M. Y. Berezin and S. Achilefu, Chem. Rev., 2010, 110, 2641ꢀ
2684; (b) K. P. Carter, A. M. Young and A. E. Palmer, Chem.
Rev., 2014, 114, 4564ꢀ4601; (c) E. M. Nolan and S. J. Lippard,
Chem. Rev., 2008, 108, 3443ꢀ3480; (d) X. Chen, T. Pradhan, F.
Wang, J. S. Kim and J. Yoon, Chem. Rev., 2012, 112, 1910ꢀ1956;
(e) M. Kaur and D. H. Choi, Chem. Soc. Rev., 2015, 44, 58ꢀ77; (f)
Z. Guo, S. Park, J. Yoon and I. Shin, Chem. Soc. Rev., 2014, 43, 16ꢀ
29; (g) L. Yuan, W. Lin, K. Zheng, L. He and W. Huang, Chem.
Soc. Rev., 2013, 42, 622ꢀ661; (h) J. Fan, M. Hu, P. Zhan and X.
Peng, Chem. Soc. Rev., 2013, 42, 29ꢀ43; (i) J. Du, M. Hu, J. Fan and
X. Peng, Chem. Soc. Rev., 2012, 41, 4511ꢀ4535; (j) W. Xuan, C.
Chen, Y. Cao, W. He, W. Jiang, K. Liu and W. Wang, Chem.
Commun., 2012, 48, 7292ꢀ7294; (k) M. Vedamalai and S. P. Wu,
Org. Biomol. Chem., 2012, 10, 5410ꢀ5416; (l) J. Liu, Y. Q. Sun, P.
Wang, J. Zhang and W. Guo, Analyst, 2013, 138, 2654ꢀ2660; (m) F.
Song, S. Watanabe, P. E. Floreancig, and K. Koide, J. Am. Chem.
Soc., 2008, 130, 16460ꢀ16461; (n) H. Jiang, J. Jiang, J. Cheng, W.
Dou, X. Tang, L. Yang, W. Liu and D. Bai, New J.Chem., 2014, 38,
109ꢀ114; (o) L. Chen, L. Yang, H. Li, Y. Gao, D. Deng, Y. Wu and
L. Ma, Inorg. Chem., 2011, 50, 10028ꢀ10032; (p) M. Saleem, R.
Abdullah, A. Ali, B. J. Park, E. H. Choi, I. S. Hong and K. H. Lee,
Anal. Methods, 2014, 6, 3588ꢀ3597.
MS1
MS1+Hg2+
800
600
400
200
0
4
6
8
10
12
pH
4
(a) M. Tian and H. Ihmels, Chem. Commun., 2009, 3175ꢀ3177; (b)
N. Kumari, N. Dey, S. Jha and S. Bhattachary, ACS Appl. Mater.
Interfaces, 2013, 5, 2438ꢀ2445; (c) S. Madhu, R. Kalaiyarasi, S. K.
Basu, S. Jadhav and M. Ravikanth, J. Mater. Chem. C, 2014, 2,
30 Fig. 5 Effect of the pH on the fluorescence emission of MS1 (10 ꢀM)
alone and MS1 (10 ꢀM) reacted with Hg2+ (3.0 equiv.).
This journal is © The Royal Society of Chemistry [year]
Journal Name, [year], [vol], 00–00 | 3

RSC Advances
Page 4 of 4
View Article Online
DOI: 10.1039/C4RA16479B
2534ꢀ2544; (d) M. Tian, L. Liu, Y. Li, R. Hu, T. Liu, H. Liu, S.
Wang and Y. Li, Chem. Commun., 2014, 50, 2055ꢀ2057.
5
(a) P. Dinake, P. E. Prokhorova, V. S. Talanov, R. J. Butcher and G.
G. Talanova, Tetrahedron Lett., 2010, 51, 5016ꢀ5019; (b) J. H.
Kim, J. Y. Noh, I. H. Hwang, J. J. Lee and C. Kim, Tetrahedron
Lett., 2013, 54, 4001ꢀ4005; (c) P. Srivastava, R. Ali, S. S. Razi, M.
Shahid, S. Patnaik and A. Misra, Tetrahedron Lett., 2013, 54, 3688ꢀ
3693; (d) L. N. Neupane, J. Y. Park, J. H. Park and K. H. Lee, Org.
Lett., 2013, 15, 254ꢀ257; (e) M. Kumar, N. Kumar, V. Bhalla, H.
Singh, P. R. Sharma and T. Kaur, Org. Lett., 2011, 13, 1422ꢀ1425;
(f) M. Kumar, S. I. Reja and V. Bhalla, Org. Lett., 2012, 14, 6084ꢀ
6087.
5
10
15
20
25
30
6
(a) Y. Peng, Y. M. Dong, M. Dong and Y. W. Wang, J. Org. Chem.,
2012, 77, 9072ꢀ9080; (b) A. Roy, D. Kand, T. Saha and P. Talukdar,
Chem. Commun., 2014, 50, 5510ꢀ5513; (c) D. Kim, S. Singha, T.
Wang, E. Seo, J. H. Lee, S. J. Lee, K. H. Kim and K. H. Ahn, Chem.
Commun., 2012, 48, 10243ꢀ10245; (d) J. T. Yeh, P. Venkatesan and
S. P. Wu, New J. Chem., 2014, 38, 6198ꢀ6204.
(a) M. Santra, B. Roy and K. H. Ahn, Org. Lett., 2011, 13, 3422ꢀ
3425; (b) J. Jiang, W. Liu, J. Cheng, L. Yang, H. Jiang, D. bai and
W. Liu, Chem. Commun., 2012, 48, 8371ꢀ8373; (c) Y. S. Cho, K. H.
Ahn, Tetrahedron Lett., 2010, 51, 3852ꢀ3854; (d) S. Zhang, J. Geng,
W. Yang and X. Zhang, RSC Adv., 2014, 4, 12596ꢀ12600.
(a) K. Wu, Y. Gao, Z. Yu, F. Yu, J. Jiang, J. Guo and Y. Han, Anal.
Methods, 2014, 6, 3560ꢀ3563; (b) X. Li, Y. Gong, K. Wu, S. H.
Liang, J. Cao, B. Yang, Y. Hu and Y. Han, RSC Adv., 2014, 4,
36106ꢀ36109; (c) X. Li, C. Yang, K. Wu, Y. Hu, Y. Han and S. H.
Liang, Theranostics, 2014, 4, 1233ꢀ1238; (d) J. Liu, K. Wu, S. Li,
T. Song, Y. Han and X. Li, Dalton Trans., 2013, 42, 3854ꢀ3859; (e)
J. Liu, K. Wu, X. Li, Y. Han and M. Xia, RSC Adv., 2013, 3, 8924ꢀ
8928.
7
8
4
| Journal Name, [year], [vol], 00–00
This journal is © The Royal Society of Chemistry [year]