A simple colorimetric chemosensor bearing a carboxylic acid group with high selectivity for CN-

Article abstract of DOI:10.1016/j.saa.2014.06.001

A new simple 'naked eye' chemosensor 1 (sodium (E)-2-((2-(3-hydroxy-2- naphthoyl)hydrazono)methyl)benzoate) has been synthesized for detection of CN^- in a mixture of DMF/H₂O (9:1). The sensor 1 comprises of a naphthoic hydrazide as efficient hydrogen bonding donor group and a benzoic acid as the moiety with the water solubility. The receptor 1 showed high selectivity toward cyanide ions in a 1:1 stoichiometric manner, which induces a fast color change from colorless to yellow for CN^- over other anions. Therefore, receptor 1 could be useful for cyanide detection in aqueous environment, displaying a high distinguishable selectivity from hydrogen bonded anions and being clearly visible to the naked eye.

Full text of DOI:10.1016/j.saa.2014.06.001

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 132 (2014) 771–775
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
A simple colorimetric chemosensor bearing a carboxylic acid group
with high selectivity for CNÀ
⇑
⇑
Gyeong Jin Park, Ye Won Choi, Dongkuk Lee , Cheal Kim
Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 139-743, Republic of Korea
Department of Interdisciplinary Bio IT Materials, Seoul National University of Science and Technology, Seoul 139-743, Republic of Korea
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
ꢀ
ꢀ
A new Schiff base was synthesized as
a colorimetric CNÀ sensor.
Sensor 1 exhibited a color change
from colorless to yellow via a simple
deprotonation.
ꢀ
Sensor 1 showed high selectivity for
CNÀ over other various anions.
a r t i c l e i n f o
a b s t r a c t
Article history:
A
new simple ‘naked eye’ chemosensor 1 (sodium (E)-2-((2-(3-hydroxy-2-naphthoyl)hydrazono)
methyl)benzoate) has been synthesized for detection of CNÀ in a mixture of DMF/H2O (9:1). The sensor
1 comprises of a naphthoic hydrazide as efficient hydrogen bonding donor group and a benzoic acid as
the moiety with the water solubility. The receptor 1 showed high selectivity toward cyanide ions in a
1:1 stoichiometric manner, which induces a fast color change from colorless to yellow for CNÀ over other
anions. Therefore, receptor 1 could be useful for cyanide detection in aqueous environment, displaying a
high distinguishable selectivity from hydrogen bonded anions and being clearly visible to the naked eye.
Ó 2014 Elsevier B.V. All rights reserved.
Received 15 March 2014
Received in revised form 30 April 2014
Accepted 1 June 2014
Available online 12 June 2014
Keywords:
Cyanide
Colorimetric
Naphthoic hydrazide
Carboxylic acid
Deprotonation
Introduction
lurgy as well as in gold mining [3]. In addition, it is much more
famous due to its toxicity to the environment and to mammals,
The importance of anions in biological, environmental and
chemical processes has affected the development of anion sensing
instruments [1]. Among various anions, cyanide has been exten-
sively studied [2], because the cyanide anion is very often used
industrially in the synthesis of organic chemicals, polymers, metal-
leading to convulsions, loss of consciousness, and eventual death
[4]. Consequently, cyanide selective detection and quantification
are very important, which has been the object of increasing inves-
tigation [5].
Although previous works have involved the development of a
wide variety of chemical and physical sensors for the detection
of CNÀ, improving the detection selectivity among coexisting
anions has been challenging [6]. In addition, most of these methods
require expensive equipment and involve time-consuming and
laborious procedures that can be carried out only by trained pro-
fessionals, significantly restricting the practical application of these
⇑
Corresponding authors at: Department of Fine Chemistry, Seoul National
University of Science and Technology, Seoul 139-743, Republic of Korea. Tel.: +82
2 970 6693; fax: +82 2 973 9149.
E-mail addresses: dongkuk@seoultech.ac.kr (D. Lee), chealkim@seoultech.ac.kr
(C. Kim).
http://dx.doi.org/10.1016/j.saa.2014.06.001
1386-1425/Ó 2014 Elsevier B.V. All rights reserved.

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G.J. Park et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 132 (2014) 771–775
CNÀ sensors [7]. For simplicity, convenience and low cost, easily-
prepared CNÀ colorimetric chemosensors are needed [8].
3 h at room temperature. The white powder was produced. The
white solid was collected by filtration, washed with diethyl ether
and air-dried. Yield: 0.29 g (82.3%). 1H NMR (DMSO-d6, 400 MHz)
d 12.80 (s, 2H), 9.26 (s, 1H), 8.56 (s, 1H), 8.05 (d, 1H), 7.85
(t, 2H), 7.71 (d, 1H), 7.53 (t, 2H), 7.47 (t, 2H), 7.40 (s, 1H), 7.31
(t, 1H) ppm. 13C NMR (DMSO-d6, 100 MHz) d 170.25, 164.51,
155.97, 148.88, 136.74, 133.93, 131.29, 130.7, 130.11, 129.44,
128.68, 127.15, 126.73, 126.33, 123.93, 121.01, 111.52 ppm. HRMS
(ESI): m/z calcd. for C19H13N2NaO4 ([M–Na+]), 333.09; found,
333.13. Anal. calcd. for C19H13N2NaO4 (356.31): C, 64.05; H, 3.68;
N, 7.86. Found: C, 64.01; H, 3.90; N, 7.32%.
Over the past decades, many efforts have been devoted to
design various chemosensors for the detection of cyanide, includ-
ing the formation of cyanide complexes with transition metals
[9], nucleophilic addition reactions to carbonyl groups [10], the
displacement approach [11], hydrogen-bonding interactions [12]
and deprotonation [13]. Among them, the deprotonation process
of sensors with CNÀ has scarcely been studied. Moreover, the
development of colorimetric chemosensors using deprotonation
mechanism that can discriminate CNÀ from FÀ and OAcÀ is still a
challenge as they are also well known as anions with the high basi-
city and the hydrogen bonding ability [14]. Thus, a technique to
trace and visualize cyanide ions would be highly demanded.
In view of this requirement and as part of our research effort
devoted to cyanide ion recognition, we have, first, considered the
possibility of a hydrogen bond between the amide (CONH)/OH
moieties of 3-hydroxy-2-naphthoic hydrazide and the targeted
anions. Secondly, we tried to incorporate the carboxylate moiety
to a sensor to increase water solubility. Importantly, the chemo-
sensors with the water-soluble acid groups have hardly been
reported. Our strategy led us to synthesize a new naphthoic hydra-
zide-carboxylate conjugated optical probe for CNÀ where the
naphthoic hydrazide works as a H-bonding donor and the carbox-
ylate group increases water solubility.
UV–vis measurements
Receptor 1 (3.56 mg, 0.01 mmol) was dissolved in DMF (1 mL)
and 9
(9:1, v/v) to make the final concentration of 30
monium cyanide (TEACN, 15.6 mg, 0.1 mmol) was dissolved in a
mixture of DMF/H2O (v/v = 9:1, 1 mL). 9–90
L of the CNÀ solution
(100 mM) were transferred to each receptor solution (30 M)
lL of the 1 (10 mM) were diluted with 2.991 mL DMF/H2O
l
M. Tetraethylam-
l
l
prepared above. After shaking the vials for a few minutes, UV–vis
spectra were taken at room temperature.
Competition with other anions
Herein, we report a new chemosensor 1 for CNÀ, which was
synthesized in one step by condensation reaction of 3-hydroxy-
2-naphthoic hydrazide and carboxylate (Scheme 1). Receptor 1
can detect cyanide by color change from colorless to yellow via
the ‘naked-eye’ with high selectivity in aqueous environment
(DMF/H2O = 9/1).
Receptor 1 (3.56 mg, 0.01 mmol) was dissolved in DMF and 9
of the 1 (10 mM) were diluted with 2.991 mL DMF/H2O (9:1, v/v)
lL
to make the final concentration of 30 lM. Tetraethylammonium
salt (FÀ, BrÀ, ClÀ, IÀ, and CNÀ; 0.1 mmol) or tetrabutylammonium
salt (AcOÀ and H2POÀ4 ; 0.1 mmol) were dissolved in a mixture of
DMF/H2O (v/v = 9:1, 1 mL), respectively. 45
lL of each anion
solution (100 mM) were taken and added into 3 mL of each 1 solu-
Experimental
tion (30 lM) prepared above to make 50 equiv. Then, 50 lL of
CNÀ solution (100 mM) were added into the mixed solution of each
metal ion and 1 to make 50 equiv. After shaking the vials for a few
minutes, UV–vis spectra were taken at room temperature.
Reagent and apparatus
All the solvents and reagents (analytical grade and spectro-
scopic grade) were obtained commercially and used as received.
1H NMR and 13C NMR measurements were performed on a Varian
400 MHz spectrometer and chemical shifts are recorded in ppm.
Absorption spectra were recorded using a Perkin Elmer model
Lambda 2S UV–vis spectrometer at room temperature. Electro-
spray ionization mass spectra (ESI-mass) were collected on a
Thermo Finnigan (San Jose, CA, USA) LCQTM Advantage MAX quad-
rupole ion trap instrument. Elemental analysis for carbon, nitro-
gen, and hydrogen was carried out by using a Flash EA 1112
elemental analyzer (thermo) in Organic Chemistry Research Center
of Sogang University, Korea.
Job plot measurement
Receptor 1 (3.56 mg, 0.01 mmol) was dissolved in a mixture of
DMF/H2O (v/v = 9:1, 1 mL). 12, 10.8, 9.6, 8.4, 7.2, 6.0, 4.8, 3.6, 2.4,
and 1.2 lL of the 1 solution were taken and transferred to vials.
Each vial was diluted with DMF/H2O (9:1, v/v) to make a total
volume of 2.988 mL. TEACN (1.56 mg, 0.01 mmol) was dissolved
in DMF/H2O (v/v = 9:1, 1 mL). 0, 1.2, 2.4, 3.6, 4.8, 6.0, 7.2, 8.4, 9.6,
10.8, and 12 l
L of the CNÀ solution were added to each diluted 1
solution. Each vial had a total volume of 3 mL. After shaking the
vials for a few minutes, UV–vis spectra were taken at room
temperature.
Synthesis of receptor 1
3-Hydroxy-2-naphthoic acid hydrazide (0.20 g, 1 mmol) and 2-
formylbenzoic acid (0.18 g, 1.2 mmol) were dissolved in 30 mL of
ethanol. Then, sodium hydroxide (0.04 g, 1.2 mmol) in 5 mL of
H2O was added into the reaction mixture, which was stirred for
1H NMR titration of 1-CNÀ
Four NMR tubes of 1 (0.76 mg, 0.002 mmol) dissolved in DMF-
d7 (0.7 mL) were prepared, and four different equiv (0, 0.5, 1,
Scheme 1. Synthetic procedure of 1.

G.J. Park et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 132 (2014) 771–775
773
Results and discussion
The colorimetric chemosensor 1 for cyanide was synthesized by
condensing of 3-hydroxy-2-naphthoic acid hydrazide with 2-form-
ylbenzoic acid (Scheme 1), and characterized by 1H and 13C NMR,
ESI-mass spectrometry, and elemental analysis.
Sensing properties of 1 toward anions in aqueous solution
The colorimetric sensing abilities of 1 were primarily investi-
gated in a mixture of DMF/H2O (9:1, v/v) upon addition of various
anions (FÀ, AcOÀ, ClÀ, BrÀ, IÀ, H2POÀ4 and CNÀ). Upon the addition of
50 equiv of each anion, the 1 showed almost no change in absorp-
tion peak in the presence of FÀ, AcOÀ, ClÀ, BrÀ, IÀ and H2POÀ4
(Fig. 1a). Most importantly, only CNÀ showed a distinct spectral
change (Fig. 1a) and a color change from colorless to yellow
(Fig. 1b), indicating that receptor 1 can serve as a potential candi-
date of ‘‘naked-eye’’ chemosensor for CNÀ in aqueous solution.
The recognition properties of 1 with CNÀ were further studied
by UV–vis titration experiments. On treatment with CNÀ of a solu-
tion of 1, the absorption band at 374 nm slightly decreased, and
three new bands at 308, 336 and 433 nm gradually reached max-
ima at 50 equiv of CNÀ (Fig. 2). Meanwhile, two clear isosbestic
points were observed at 369 and 381 nm, indicating the formation
of the only one species between 1 and CNÀ. The yellow color of the
solution may be due to the deprotonation of phenolic and enol OH
groups followed by hydrogen bonding with cyanide ions [15]. As
shown in Scheme 2, the potential H-bonding pocket defined by
two OH protons which have the potential to bind anions in a
chelate mode, tends to bring the cyanide to their vicinity [4]. To
further confirm the sensing mechanism between 1 and CNÀ, the
interaction between 1 and OHÀ was also investigated. UV–vis
spectral change of 1 upon addition of OHÀ was similar with that
of 1 obtained from the addition of CNÀ, which indicated the depro-
tonation between 1 and CNÀ (inset in Fig. 1).
Fig. 1. (a) UV–vis spectra changes of 1 (30
of 50 equiv of various anions. (b) Colorimetric changes of 1 (30
l
M, DMF-buffer (9:1, v/v)) upon addition
M) upon the
l
addition of various anions (50 equiv). Inset: Changes in the UV–vis spectra of
receptor 1 upon addition of CNÀ and OHÀ, respectively, in DMF-buffer (9:1, v/v).
The Job plot showed a 1:1 stoichiometry between 1 and CNÀ
(Fig. S1) [16], which was further confirmed by ESI-mass spectrom-
etry analysis (Fig. 3). The negative-ion mass spectrum of 1 upon
addition of 1 equiv of CNÀ showed the formation of the 12À [m/z:
593.30; calcd., 593.27]. From the UV–vis titration data, the associ-
ation constant for 1 with CNÀ was determined as 1.4 ( 0.1) Â
102 MÀ1 using Benesi–Hildebrand equation (Fig. S2) [17]. This
value is within the range of those (1.0–1.0 Â 105) reported for
CNÀ sensing chemosensors [18]. The detection limit (3
r/k) of
receptor 1 for the analysis of CNÀ ions was calculated to be
7.0 Â 10À4 M (Fig. S3) [19].
Fig. 2. UV–vis spectra changes of 1 (30 lM) in the presence of different concen-
trations of CNÀ ion in DMF-buffer solution (9:1, v/v). Inset: The enlarged spectra at
the range of 365–390 nm.
The preferential selectivity of 1 as a naked eye chemosensor for
the detection of CNÀ was studied in the presence of various com-
peting anions. For competition studies, receptor 1 was treated with
50 equiv of CNÀ in the presence of 50 equiv of other anions, as indi-
cated in Fig. 4. There was no interference in the detection of CNÀ in
the presence of FÀ, ClÀ, BrÀ, IÀ, OAcÀ, and H2POÀ4 . Thus, 1 could be
used as a selective colorimetric sensor for CNÀ in the presence of
the competing anions.
2 equiv) of tetraethylammonium cyanide dissolved in DMF-d7
(0.3 mL) were added to the 1 solution separately. After shaking
them for a minute, their 1H NMR spectra were taken at room
temperature.
Scheme 2. Proposed sensing mechanism of 1 for cyanide.

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G.J. Park et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 132 (2014) 771–775
cyanide occurs by the deprotonation pathway, not by the addition
reaction of cyanide to the imine moiety of 1. Furthermore, no shift
in the position of proton signals was observed on any further addi-
tion of CNÀ (>1.0 equiv). Based on ESI-mass spectrometry analysis
and 1H NMR study, we finally propose that the sensing ability of
receptor 1 is due to the deprotonation process by CNÀ, as shown
in Scheme 2.
Conclusion
We synthesized
a carboxylic-functionalized water-soluble
imine-based colorimetric sensor 1, which displays high selectivity
for detection of cyanide in aqueous solution. 1 sensed CNÀ in a 1:1
stoichiometric manner, which induces an obvious color change
from colorless to yellow. Such selectivity results from a simple
deprotonation between 1 with the H-bonding donor group and
CNÀ. Consequently, sensor 1 appears to be a practical system for
monitoring CNÀ in aqueous solution.
Fig. 3. Negative-ion electrospray ionization mass spectrum of 1 upon addition of
TEA(CN) (1.0 equiv) in acetonitrile.
Acknowledgements
Basic Science Research Program through the National Research
Foundation of Korea (NRF) funded by the Ministry of Education,
Science and Technology (2012001725, 2011K000675, and
2012008875) are gratefully acknowledged. We thank Prof. Mi Sook
Seo (Ewha Womans University) for ESI-mass running and helpful
comments.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.saa.2014.06.001.
References
[1] (a) X. Lou, D. Qu, Q. Li, Z. Li, Chem. Commun. 48 (2012) 8462–8477;
(b) M. Wenzel, J.R. Hiscock, P.A. Gale, Chem. Soc. Rev. 41 (2012) 480–520;
(c) Y.W. Choi, G.J. Park, Y.J. Na, H.Y. Jo, S.A. Lee, G.R. You, C. Kim, Sens. Actuat. B
194 (2014) 343–352;
(d) E.J. Song, H. Kim, I.H. Hwang, K.B. Kim, A.R. Kim, I. Noh, C. Kim, Sens. Actuat.
B 195 (2014) 36–43;
(e) A. Bianchi, K. Bowman, E. Garcia-Espana, Supramolecular Chemistry of
Anions, Wiley-VCH, New York, 1997;
(f) J.J. Park, Y. Kim, C. Kim, J. Kang, Tetrahedron Lett. 52 (2011) 2759–2763;
(g) Y. Kim, H. Kwak, S.J. Lee, J.S. Lee, H.J. Kwon, S.H. Nam, K. Lee, C. Kim,
Tetrahedron 62 (2006) 9635–9640;
(h) J.J. Park, Y. Kim, C. Kim, J. Kang, Tetrahedron Lett. 52 (2011) 3361;
(i) P.D. Beer, P.A. Gale, Angew. Chem. 113 (2001) 502–532;
(j) J. Kang, S.P. Jang, Y. Kim, J.H. Lee, E.B. Park, H.G. Lee, J.H. Kim, Y. Kim, S. Kim,
C. Kim, Tetrahedron Lett. 51 (2010) 6658–6662.
Fig. 4. (a) Competitive selectivity of 1 (30 l
M) towards CNÀ (50 equiv) in the
[2] (a) Z. Xu, X. Chen, H.N. Kim, J. Yoon, Chem. Soc. Rev. 39 (2010) 127–137;
(b) J. Kang, E.J. Song, H. Kim, Y. Kim, Y. Kim, S. Kim, C. Kim, Tetrahedron Lett. 54
(2013) 1015–1019.
presence of other anions (50 equiv). (b) Colorimetric changes of 1 (30 lM) in the
presence of CNÀ (50 equiv) and other anions (50 equiv).
[3] (a) G. Qian, X.Z. Li, Z.Y. Wang, J. Mater. Chem. 19 (2009) 522–530;
(b) L.H. Peng, M. Wang, G.X. Zhang, D.Q. Zhang, D.B. Zhu, Org. Lett. 11 (2009)
1943–1946;
To further understand the nature of interaction between sensor
1 and the cyanide, 1H NMR study was initiated in DMF-d7 (Fig. S4).
Upon addition of 0.2 equiv of TEA(CN) as the cyanide source, the
singlet peaks (H1 and H8) of naphthol and enol OH moieties were
downshifted from 13.01 ppm to 13.79 ppm. The H7 in the naphthol
ring and H9 of the imine group were also downshifted from
9.53 ppm to 9.57 ppm and from 8.79 ppm to 8.81 ppm, respec-
tively. After the addition of 1 equiv of cyanide, the singlet protons,
H1 and H8, disappeared. Meanwhile, all aromatic protons were
shifted to upfield, which suggests that the negative charges gener-
ated from the deprotonation of 1 by CNÀ were delocalized over the
whole receptor molecule. In addition, no new peak was observed in
the range of 5–6 ppm, which indicates exclusion for the nucleo-
philic addition of cyanide to the imine moiety. Therefore, this
result could support the fact that the sensing mechanism of 1 for
(c) D.S. Kim, Y.M. Chung, M. Jun, K.H. Ahn, J. Org. Chem. 74 (2009) 4849–4854;
(d) S. Vallejos, P. Estévez, F.C. García, F. Serna, J.L. Peña, J.M. García, Chem.
Commun. 46 (2010) 7951–7953;
(e) Z.C. Xu, X.Q. Chen, H.N. Kim, J.Y. Yoon, Chem. Soc. Rev. 39 (2010) 127–137.
[4] (a) Y. Sun, Y. Liu, M. Chen, W. Guo, Talanta 80 (2009) 996–1000;
(b) C. Chen, Y. Chen, C. Chen, S. Sun, Org. Lett. 8 (2006) 5053–5056;
(c) Y. Sun, G. Wang, W. Guo, Tetrahedron 65 (2009) 3480–3485;
(d) R. Sivakumar, V. Reena, N. Ananthi, M. Babu, S. Anandan, S. Velmathi,
Spectrochim. Chem. Acta A 75 (2010) 1146–1151;
(e) K.K.W. Mak, H. Yanase, R. Renneberg, Biosens. Bioelectron. 20 (2005)
2581–2593;
(f) K. Kim, O.G. Tsay, D.A. Atwood, D.G. Churchill, Chem. Rev. 111 (2011) 5345–
5403.
[5] (a) Z. Xu, J. Pan, D.R. Spring, J. Cui, J. Yoon, Tetrahedron 66 (2010) 1678–1683;
(b) J. Wang, C. Ha, Tetrahedron 66 (2010) 1846–1851;
(c) J.H. Lee, A.R. Jeong, I. Shin, H. Kim, J. Hong, Org. Lett. 12 (2010) 764–767;
(d) G.W. Lee, N. Kim, K. Jeong, Org. Lett. 12 (2010) 2634–2637;
(e) S. Saha, A. Ghosh, P. Mahato, S. Mishra, S.K. Mishra, E. Suresh, S. Das, A. Das,
Org. Lett. 12 (2010) 3406–3409.

G.J. Park et al. / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 132 (2014) 771–775
775
[6] (a) Y.M. Chung, B. Raman, D. Kim, K.H. Ahn, Chem. Commun. (2006) 186–188;
(b) C. Chow, M.H.W. Lam, W. Wong, Inorg. Chem. 43 (2004) 8387–8393;
(c) F.H. Zelder, Inorg. Chem. 47 (2008) 1264–1266;
(d) G.J. Park, I.H. Hwang, E.J. Song, H. Kim, C. Kim, Tetrahedron 70 (2014)
2822–2828.
(b) T.W. Hudnall, F.P. Gabbaï, J. Am. Chem. Soc. 129 (2007) 11978–11986;
(c) S.A. Lee, G.R. You, Y.W. Choi, H.Y. Jo, A.R. Kim, I. Noh, S. Kim, Y. Kim, C. Kim,
Dalton Trans. 43 (2014) 6650–6659.
[7] (a) K. Ikebukuro, M. Honda, K. Nakanishi, Y. Nomura, Y. Masuda, K. Yokoyama,
Y. Yamauchi, I. Karube, Electroanalysis 8 (1996) 876–879;
(b) S. Licht, N. Myung, Y. Sun, Anal. Chem. 68 (1996) 954–959;
(c) L. Shang, L. Zhang, S. Dong, Analyst 134 (2009) 107–113;
(d) P.B. Vaello, E. Jover, J. Llorens, J.M. Bayona, J. Chromatogr. B 870 (2008) 17–
21;
[10] (a) J.V. Ros-Lis, R. Martínez-Máñez, J. Sato, Chem. Commun. 19 (2002) 2248–
2249;
(b) Y.K. Kim, Y.H. Lee, H.Y. Lee, M.K. Kim, G.S. Cha, K.H. Ahn, Org. Lett. 5 (2003)
4003–4006;
(c) M. Tomasulo, F.M. Raymo, Org. Lett. 7 (2005) 4633–4636;
(d) F. Heidarizadeh, F. Abadast, Oriental J. Chem. 27 (2011) 1421–1436.
[11] Y. Chung, H. Lee, K.H. Ahn, J. Org. Chem. 71 (2006) 9470–9474.
[12] H. Miyaji, J.L. Sessler, Angew. Chem., Int. Ed. 40 (2001) 154–157.
[13] N. Gimeno, X. Li, J.R. Durrant, R. Vilar, Chem. Eur. J. 14 (2008) 3006–3012.
[14] J.E. Huheey, E.A. Keiter, R.L. Keiter, Inorganic Chemistry: Principles of Structure
and Reactivity, fourth ed., Harper Collins College Publishers, New York, 1993.
[15] S.L.A. Kumar, M.S. Kumar, R.P. John, T. Muthiah, A. Sreekanth, Mater. Sci. Eng. C
33 (2013) 2519–2525.
(e) D.G. Themelis, S.C. Karastogianni, P.D. Tzanavaras, Anal. Chim. Acta 632
(2009) 93–100;
(f) A. Taheri, M. Noroozifar, M.K. Motlagh, J. Electroanal. Chem. 628 (2009) 48–
54;
(g) B.V. Pecharroman, M.D.L. de Castro, Analyst 127 (2002) 267–270;
(h) C. Giuriati, S. Cavalli, A. Gorni, D. Badocco, J. Chromatogr. A 1023 (2004)
105–112.
[8] (a) J. Yoshino, N. Kano, T. Kawashima, J. Org. Chem. 74 (2009) 7496–7498;
(b) K.P. Divya, S. Sreejith, B. Balakrishna, P. Jayamurthy, P. Anees, A.
Ajayaghosh, Chem. Commun. 46 (2010) 6069–6071;
(c) H.B. Yu, M.Y. Fu, Y. Xiao, Phys. Chem. Chem. Phys. 12 (2010) 7386–7391;
(d) X. Lv, J. Liu, Y.L. Liu, Y. Zhao, M.L. Chen, P. Wang, W. GuoSens, Actuators B
158 (2011) 405–406;
(e) J.Y. Noh, I.H. Hwang, H. Kim, E.J. Song, K.B. Kim, C. Kim, Bull. Korean Chem.
Soc. 34 (2013) 1985–1989.
[9] (a) H. Liu, X.B. Shao, M.X. Jia, X.K. Jiang, Z.T. Li, G.J. Chen, Tetrahedron 61
(2005) 8095–8100;
[16] P. Job, Ann. Chim. 9 (1928) 113–203.
[17] H.A. Benesi, J.H. Hildebrand, J. Am. Chem. Soc. 71 (1949) 703–2707.
[18] (a) W. Gong, Q. Zhang, L. Shang, B. Gao, G. Ning, Sens. Actuat. B 177 (2013)
322–326;
(b) Y.M. Hijji, B. Barare, Y. Zhang, Sens. Actuat. B 169 (2012) 106–112;
(c) H. Tavallali, G. Deilamy-Rad, A. Parhami, S. Kiyani, Spectrochim. Acta Part A
121 (2014) 139–146;
(d) D. Kim, Y. Chung, M. Jun, K.H. Ahn, J. Org. Chem. 74 (2009) 4849–4854.
[19] Y.K. Tsui, S. Devaraj, Y.P. Yen, Sens. Actuat. B 161 (2012) 510–519.