Dual detection highly selective colorimetric chemosensors for fluoride and copper(II) ions based on imine-phenol derivative

Article abstract of DOI:10.14233/ajchem.2020.22442

A simple dual detection using colorimetric chemosensor, imine-phenol derivative L (bearing a 2-iminephenol group as a binding unit and a-nitrophenylazo group as a signaling unit), were synthesized for a high yield in two simple steps. Complexations of chemosensor L with various anions in acetonitrile solvent and other metal ions in DMSO/H2O solvent were monitored by UV-visible spectroscopy. The results indicated that the chemosensor L showed high selectivity for F^? and Cu²⁺ ions. Furthermore, the complexes for L-F^? and L-Cu²⁺ were evaluated by computational chemistry using a B3LYP/6-31G (d,p) and a B3LYP/6-311G (d,p) level of calculation. The complexes between L with F^? and Cu²⁺ were magenta and yellow colored, respectively. Chemosensor L can be applied for the analysis of F^? and Cu²⁺ ions with naked-eye detection making colour comparisons between the standard and the real sample. Most importantly, semi-qualitative detection of Cu²⁺ in water solution were successfully carried out with the developed test kit using chemosensor L.

Full text of DOI:10.14233/ajchem.2020.22442

Asian Journal of Chemistry; Vol. 32, No. 4 (2020), 803-809
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2020.22442
Dual Detection Highly Selective Colorimetric Chemosensors for
Fluorideand Copper(II) Ions Based on Imine-Phenol Derivative
1
1
1
2
1,*
PHOOMIRUT NUSUWAN , PIYADA JITTANGPRASERT , MAYUSO KUNO , KEM PUMSA-ARD and PAN TONGRAUNG
1
2
Department of Chemistry, Faculty of Science, Srinakharinwirot University, Wattana, Bangkok 10110, Thailand
Department of Physics, Faculty of Science, Srinakharinwirot University, Wattana, Bangkok 10110, Thailand
*
Corresponding author: E-mail: pan15164649@gmail.com
Received: 12 September 2019; Accepted: 8 November 2019;
Published online: 25 February 2020;
AJC-19795
A simple dual detection using colorimetric chemosensor, imine-phenol derivative L (bearing a 2-iminephenol group as a binding unit and
a-nitrophenylazo group as a signaling unit), were synthesized for a high yield in two simple steps. Complexations of chemosensor L with
various anions in acetonitrile solvent and other metal ions in DMSO/H O solvent were monitored by UV-visible spectroscopy. The results
2
−
2
+
−
2
+
indicated that the chemosensor L showed high selectivity for F and Cu ions. Furthermore, the complexes for L-F and L-Cu were
evaluated by computational chemistry using a B3LYP/6-31G (d,p) and a B3LYP/6-311G (d,p) level of calculation. The complexes
−
2+
−
2+
between L with F and Cu were magenta and yellow colored, respectively. Chemosensor L can be applied for the analysis of F and Cu
ions with naked-eye detection making colour comparisons between the standard and the real sample. Most importantly, semi-qualitative
detection of Cu in water solution were successfully carried out with the developed test kit using chemosensor L.
2+
2+
–
Keywords: Dual detection, Colorimetric chemosensor, Cu and F , Computational chemistry.
nation can occur in drinking water, medicines and toothpastes.
INTRODUCTION
However, fluorosis generally occurs when an excessive amount
of fluoride ion is ingested. Furthermore, these ions are also
associated with nerve gases and the refinement of uranium
used in nuclear weapon manufacture. Many designs and synth-
eses of highly sensitive and selective chemosensors for fluoride
ion have been reported. Thus, development of a chemosensor
for fluoride anion is of great importance for the environment
and human healthcare.
In a view of crucial roles, design and synthesis of artificial
chemosensors that can recognize ionic species for selective
and sensitive quantification of biological, environmental, ind-
ustrial and chemical processes continues to be a considerable
interesting research area of supramolecular chemistry.Anions
and metal ions have especially attracted the interests of the
researchers in recent years [1]. Because of their advantages of
simple instrumentation, low cost and facile analysis, these the
chemosensors allow direct naked-eye detection of ions with
no equipment required. Furthermore, many efficient colori-
metric and fluorescent sensors for anion and/or metal ions have
been developed in the past two decades [2,3].
Among all the anions, fluoride ion, the smallest anion
compared to other halides with a high charge density and a
hard Lewis basic nature, is significant due to its role in dental
care and treatment of osteoporosis and also an attractive target
for sensor design. However, when the fluoride ion exceeds its
normal level, it may cause diseases such as fluorosis, thyroid
activity depression and bone disorders. In addition contami-
On the other hand, among the transition-metal ions of
interest, copper ion is not only the third in abundance among
the essential heavy metal ions in the human body [4], but also
an essential trace element for many biological processes and
systems. Copper ion has been suspected of causing infant liver
damage in recent years. For this reason, WHO has approved 2
ppm of copper as the permissible limit in drinking water. More-
2+
over, deficiency of Cu leads to Menkes disease, but high
levels may causeAlzheimer or Wilson disease, gastrointestinal
disorders, and kidney damage [5,6]. Hence, an accurate and
facile detection of copper and fluoride ions is important. Some
modern analytical techniques including atomic absorption/
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804 Nusuwan et al.
Asian J. Chem.
2
+
2+
emission spectrometry, inductively coupled plasma mass spectro-
scopy, ion-exchange chromatography and ion selective elec-
trodes techniques are based on instrumental analysis. Since
several papers describe colorimetric/fluorescent chemosensors
having distinctive advantages over other types due to their
simplicity, high sensitivity and fast response time, many research
Zn and Cd ) were purchased in the form of perchlorate salts
from Sigma-Aldrich and stored in desiccators containing self-
indicating silica. The chemosensor L was synthesized accor-
ding to Scheme-I.
All the experiments were conducted at room temperature.
All new compounds were fully characterized via standard spectro-
scopic techniques. UV-visible spectra were conducted on a
Shimadzu UV-Vis (Model 2401PC) spectrophotometer in the
wavelength range of 200-800 nm with a quartz cuvette of 1 cm
−
2+
studies of F and/or Cu sensing by synthesized selective colori-
metric/fluorescent chemosensors have been reported and investi-
gated [7-9]. Some reports presented the sensors for simul-
−
2+
1
13
taneous detection of F and Cu . For sample, Sahin andAkceylan
10] reported a new synthesized phenanthrene based fluore-
path length. The H NMR and C NMR spectra were recorded
on a BrukerAvance 300 FT 300 MHz NMR with CDCl and
as solvent. The H NMR and C NMR chemical
[
3
2
+
−
1
13
scent calixarene for detection of Cu and F by fluorescence
DMSO-d
6
2
+
−
spectroscopy. With the addition of Cu and F , the fluorescence
was severely quenched. Furthermore,Yu et al. [11] reported a
new rhodamine based turn "off-on" fluorescent chemosensor
bearing imines and thiourea moiety. The approach showed dual
response for Cu by enhancement in the fluorescence intensity
of RBS upon binding with Cu and higher selectivity for only
shift values were expressed in ppm. Mass spectra were operated
on a BrukerDaltonics (micro TOF).
Synthesis of 5-(4-nitrophenylimine)-2-hydroxybenzal-
dehyde (1): The mixture of p-nitroaniline solution (0.025 mol
in a small quantity of water) and 3 mL of 37 % aq. HCl solution
was stired at 0 ºC. 10 mL of 20 % aq NaNO solution was then
added to the mixture. The obtained solution was stirred for 1 h,
affording a yellow solution. Salicylaldehyde (0.025 mol) was
2+
2+
2
−
F and led to a distinct colour change that can be observed by
the naked eye. In addition, Liu et al. [12] reported a novel 1,8-
naphthalimide derivative was designed and synthesized for
dissolved in a Na
2
CO
3
solution (9 g Na
2
CO
3
in 75 mL H O)
2
2+
−
Cu and F naked-eye recognition. However, from the preli-
minary application of this sensor, only fluorine contents in
real samples were performed and reported. Thus, a novel imine-
phenol derivative (L) bearing a 2-iminephenol group as a
binding unit and a p-nitrophenylazo group as a signaling unit
was designed and synthesized for highly selective detection
and the resulting solution of salicylaldehyde was added
dropwise to the yellow solution and was stired for 4h to obtain
the brown crude solid [13]. The product was filtered and recrys-
tallized in methanol to afford a pure yellow product (1) with a
1
yield of 78 %. H NMR (CDCl
3
, 300 MHz, δ ppm): 7.13-8.22
(d, 2H,ArH), 8.27 (s, 1H,ArH), 8.00-8.39 (d, 4H,ArH), 10.04
(s, 1H,OH), 11.45 (s,1H, CH O).
2
+
−
of Cu and F with the naked eye. The sensitivity and
−
2+
selectivity for F and Cu were systematically investigated by
UV-visible spectroscopy. The chemosensor L was used for the
semi-quantitative analysis of F in samples and Cu in an
aqueous mixture with an organic solvent. The structure was
confirmed by the quantum mechanical calculations to elucidate
Synthesis of imine-phynol derivative (L): Compound 1
(1 g, 3.69 mmol) in ethanol (30 mL) was stirred under a nitrogen
atmosphere followed by the addition of 2-hydoxyaniline (0.4
g, 3.69 mmol) and the mixture was refluxed for 24 h. The product
was filtered and recrystallized from ethanol to afford a pure
−
2+
−
2+
1
the complex formation between L-F and L-Cu .
magenta product (L) with a yield of 77.10 % (Scheme-I). H
NMR (DMSO-d
.53 (d, 1H, ArH), 8.27 (d, 1H, ArH), 7.97-8.39 (d, 4H,
ArH), 9.23 (s, 1H, CH), 10.18 (s,1H, OH), 15.28 (s, 1H, OH).
6
): δ 6.89-6.98 (m, 4H,ArH), 7.16 (d, 1H,ArH),
EXPERIMENTAL
7
All reagents and solvents were of analytical grade and
−
−
−
2−
13
used without further purification. All anions (F , Cl , I , CO
3
,
C NMR (DMSO-d ): δ 117.03, 118.35, 119.34, 120.28,
6
2
4
−
−
−
−
SO
, OH , SCN and NO
3
) were purchased in the form of
121.16,123.42, 123.73, 125.54, 127.56, 129.27, 131.51, 132.66,
tetrabutylammonium salts and other forms fromAcros Organics
andAldrich.All of the metal ions (Cu , Ni , Fe , Mn , Co ,
143.89, 148.19, 150.98, 156.07, 160.12,171.17, 190.79. LRMS-
2+
2+
2+
2+
2+
+
TOF: m/z calcd. (found) for C19
H
14
4 4
N O : 362.34 (363.30) [M+H] .
OH
NH2
CHO
OH
OH
NH2
N
OH
1
2
) NaNO ·HCl, 0-5 °C, 1 h
2
N
+
N
OH
) Na2CO3·H2O, RT, 4 h
Ethanol, reflux, 24 h
CHO
NO2
N
N
NO2
O N
L
2
1
2+
Scheme-I: Synthetic procedureof chemosensor L Cu sensing studies of chemosensor L

Vol. 32, No. 4 (2020)
Dual Detection Highly Selective Colorimetric Chemosensors for Fluoride and Copper(II) Ions 805
1
H NMR analysis:A solution of chemosensor L (10 mM
) was titrated by adding known quantities of concen-
ion (10 equiv.), absorption bands centered at 383 and 477 nm
decrease and new strong absorption bands centered at 286.5
and 468 nm occurred with the concomitant colour change from
orange red to yellow (Fig. 1b). The complex formation between
in DMSO-d
6
−
trated solution of F (100 mM) in the form of tetrabutylamm-
onium salts. The chemical shift changes of OH protons of a
-iminephenol moiety in the chemosensor L were monitored.
DMSO-d was purchased from Sigma-Aldrich. The anion salts
and chemosensor L were dried for at least a day indynamic
vacuum prior to the experiments.
Theoretical calculations: The theoretical calculations
were carried out with Gaussian 09 software using the density
functional theory (DFT) method with B3LYP/6-31G (d,p) level
for the chemosensor L and the complex with F and with B3LYP/
-311G (d,p) level for chemosensor L and the complex with
Cu . The structural optimizations of chemosensor L and the
complexes were performed without symmetry constraints by
applying in the gas phase.
−
2+
2
chemosensor L and Cu was elucidated, as colour and UV-
2+
6
visible spectrum changes were observed, upon Cu ion addition.
On the other hand, chemosensor L exhibited no change in colour
and also absorption spectra after addition of 10 equiv. of other
metal ions in DMSO solution. This result indicates that
chemosensor L can serve as a potential candidate of a "naked-
2+
eye"chemosensor for Cu in an aqueous solution.
−
6
1.2
2
+
(a)
2+
Cu
1.0
0.8
0.6
0.4
2
+
2+
2+
2+
2+
2+
L, Ni , Fe , Mn , Co , Zn , Cd
RESULTS AND DISCUSSION
Characterization of chemosensor L: The desired selective
2+
−
colorimetric chemosensor L for Cu and F was synthesized
by a two-step procedure as shown in Scheme-I. The first step
involves the synthesis of 5-(4-nitrophenylimine)-2-hydroxy-
benzadehyde (1) and the second step involves the formation
of desired imine-phenol derivative (L)via condensation of comp-
ound 1 with 2-hydoxyaniline. The structure of chemosensor
L was characterized by H, C NMR and mass spectrometry.
The sensing ability of chemosensor L (2.5 × 10 M in
DMSO) towards a wide range of cations such as Cu ,Ni ,
0.2
0
200
300
400
500
600
700
800
Wavelength (nm)
(b)
1
13
-5
2+
2+
–5
Fig. 1. (a) Changing absorption spectra of L (2.5 × 10 M) after the addition
2+
2+
2+
2+
2+
-3
Fe , Mn , Co , Zn and Cd (0.5 × 10 M in H
2
O) was investi-
2+
of 10.0 equiv. of Cu and various metal ions in DMSO/H
(b) Image of L solution with color changes upon addition 10.0 equiv.
of to different metal ions in DMSO/H O solution
2
O solution,
gated using UV-visible spectroscopy. Fig. 1a shows the absor-
ption spectra of chemosensor L in the presence of various metal
ions in DMSO solution. The absorption spectra of chemosensor
L exhibited three absorption bands at which 283 and 383 nm
can be assigned to π-π* absorption, while an absorption at
2
The UV-vis absorption spectral variation of chemosensor
2+
L was monitored during titration with 0-1.0 equiv. of Cu . As
shown in Fig. 2, an increase in the absorption bands at 286.5
4
77 nm represents n-π* absorption corresponding to the trans-
form of azobenzene derivative [14]. Upon the addition of Cu
2+
2+
and 468.0 nm was observed upon the addition of Cu and
0
.8
.6
1.0
0.8
0.6
0.4
0.2
0
1
.0 eq
eq
0
0
0.4
0.2
0
0
0.5
1.0
1.5
2.0
2
+
–5
[
Cu ] × 10 M
2
50
350
450
Wavelength (nm)
Fig. 2. UV-visible spectra changes of L (2.5 × 10 M) in DMSO/H O solution upon addition of increasing concentrations of Cu from 0.12
550
650
–
5
2+
2
–5
–5
×
10 M to 2.56 × 10 M (0–1.0 equiv.)

806 Nusuwan et al.
Asian J. Chem.
reached the maximum at 1.0 equiv, while the absorption band
at 360 nm decreased gradually. The yellow colour of solution
observed upon addition of copper ions to chemosensor L could
possibly be attributed to the metal-induced intramolecular charge
transfer [15]. The plot of UV-visible absorption intensity versus
concentration indicated that intensities of the colorimetric
on the 24-well plate pretreated with chemosensor L. The chemo-
sensor L (100 mg/L) was added on the 24 well plate and then
2+
the water samples were re-spiked with standard Cu solutions
at different concentrations where the colour and changes were
visually monitored with the naked eye (Fig. 4). Therefore,
2+
colour test with L-Cu can be employed as a simple preliminary
2+
2+
sensor L were proportional to Cu concentration. The absor-
detection method of Cu with no requirement for sophisticated
2+
ption intensity at 468 nm was linearly related with Cu concen-
equipment.
-
5
-5
−
tration ranging from 0.12 × 10 M to 1.90 × 10 M (LOD =
F sensing studies of chemosensor L: The binding prop-
-5
2
0
.09 × 10 M, r = 0.9964).The stoichiometry for chemosensor
L-Cu complex obtained from Job′s plot by using UV-visible
data was carried out. The analytical result confirmed a 2:1
stoichiometry for the L-Cu complex, which was highly con-
sistent with the UV-visible titration experimental results. The
association constant (K ) of chemosensor L with Cu ion was
achieved as 2.47 × 10 M calculated using the analysis of
nonlinear curve fitting equation [16].
erties of chemosensor L with anion in acetonitrile were first
studied by observing changes in colour and UV-visible absor-
2+
−
−
−
ption. In the presence of various anions such as F , Cl , I ,
2+
2−
2−
−
−
−
−3
CO
3
, SO
4
, OH , SCN and NO
3
(0.5 × 10 M) (10.0 equiv.),
−
chemosensor L selectively responded to F with obvious colour
change from pale yellow to magenta (Fig. 5b). A free ligand
of chemosensor L showed absorption with λmax at 367 nm,
2+
a
-
10
-2
−
after the addition of F into chemosensor L resulting in the
Competitive experiments with various metal ions: The
disappearance of absorption band at 367 nm and appearance
of a new absorption band at 561 nm (Fig. 5a). This observation
indicated that chemosensor L forms strong hydrogen bond
2+
selectivity of chemosensor L for sensing Cu ions was deter-
2+
mined by performing competitive experiments of Cu (10
equiv.) solutions mixed with other interfering metal ions such
−
with F because of the stronger electron-withdrawing ability
2+
2+
2+
2+
2+
2+
as Ni , Fe , Mn , Co , Zn and Cd (50 equiv.). The presence
of interfering metal ions did not cause any significant change
in the UV-visible absorption as achieved by the addition of only
of p-nitrophenylazo moiety. Therefore, an acidity of proton
of hydroxyl group was enhanced. Such large bathochromic shifts
can be attributed to occurring intramolecular charge transfer
process (ICT). In contrast, the addition of other tested anions
did not show any significant change in colour and the absorption
band.
2+
Cu to the solution of chemosensor L. Thus, chemosensor L
2+
exhibits a good selectivity for Cu over other competing metal
ions (Fig. 3).
2+
0.8
L + metal ions
L + metal ions + Cu
–
F
0
0
0
0
.16
.12
.08
.04
0
(a)
0
.6
–
–
2–
L, Cl , I , CO
,
3
2–
–
SO4 , OH ,
–
–
0.4
SCN , NO
3
0.2
0
2+
Cu
2+
2+
2+
Zn
2+
Ni
2+
2+
Fe
Cd
Co
Mn
250
350
450
550
650
750
-
0.04
Fig. 3. Absorbance intensity of L (2.5 × 10 M) in the presence of Cu
10.0 equiv.) and additional various metal ions (50.0 equiv.) in
DMSO/H O solution
–
5
2+
Wavelength (nm)
(
(b)
2
2
+
Preliminary application of chemosensor L for Cu
detection: In order to investigate the practical applications of
–
5
Fig. 5. (a) The change in absorption spectra of L (2.5 × 10 M) after the
2+
chemosensor L for detecting Cu quanlitatively in a wide
selection of water samples, the samples were added with known
–
addition of 10.0 equiv. of F and various anions in CH
3
CN solution.
(b) Image of color changes of L (2.5 × 10 M) upon addition 10.0
equiv. of different anions in CH CN solution
–
5
2+
2+
amounts of Cu ions. The recognition of Cu was performed
3
2+
Fig. 4. Image of the 24 well plate for the detection of Cu at different concentrations (0.0, 0.1, 0.5, 2.0, 5.0 and 10.0 mg/L; from left to right)
in DMSO/H O solution
2

Vol. 32, No. 4 (2020)
Dual Detection Highly Selective Colorimetric Chemosensors for Fluoride and Copper(II) Ions 807
1
0.0 eq
0.8
0.6
0.4
0.2
0
0.6
0
.4
.2
0
0
eq
0
0
0.2
0.4
0.6
0.8
1.0
–
–4
[
F ] × 10
M
250
350
450
550
650
750
Wavelength (nm)
–5
–
–4
Fig. 6. UV-visible spectra changes of L (2.5 × 10 M) in CH CN solution upon addition of increasing concentrations of F from 0.09 × 10 M
3
–
4
to 2.31 × 10 M (0-10.0 equiv.)
In order to estimate the specific properties for selective
−
1.0
0.8
recognition of F and colorimetric changes associated with
−
chemosensor L toward F anion, UV-visible absorption spectra
from titration experiments were monitored. The experiments
0.6
0.4
0.2
0
−
5
were conducted using a 2.5 × 10 M solution of chemosensor
−
L in CH CN solution (Fig. 6). Upon the addition of F from
3
−
4
−4
−4
2
0
0
.09 × 10 M to 2.31 × 10 M (LOD = 0.09 × 10 M, r =
.974) to the solution, a significant decrease in the UV-visible
OH
OH
absorbance at 367 nm and a new band centered at 561 nm were
−
1
–2
observed, which indicates that chemosensor L reacts with F
Fig. 7. H NMR spectra of L (1 × 10 M) in the presence of 0.0, 0.2, 0.4,
–
0
.6, 0.8 and 1.0 equiv. of F
to form a new species. By nonlinear least-squares fitting [17]
of the spectroscopic titration curves at λmax = 561 nm, associ-
−
which indicated deprotonation of OH group. A deprotonation
of phenolic OH subunits in chemosensor L can induce a distinct
effects on the aromatic substituents via an increase of electron
density on the phenyl rings through bond propagation, which
generates a shielding effect and produce an upfield shift of
the C-H protons [18].
ation constant (K
a
) of chemosensor L toward F was calculated
8
as 5.32 × 10 M. Furthermore, from Job′s plot, a stoichiometry
−
between the chemosensor L and F in CH CN solution was
3
found to be 1:2. Based on this two-step UV-visible process, it
is proposed that in the first step, partially formed hydrogen
−
bonding between chemosensor L and F , and in the subsequent
−
Interference studies with various anions: Interference
step, a sensor was completely deprotonated with F . This batho-
−
studies for F ions were performed in the presence of other
chromic shift of the absorption band led us to propose the
transition of intramolecular charge transfer (ICT) band through
the deprotonation of chemosensor L. Therefore, these results
−
−
2−
2−
−
−
−
anions including Cl , I , CO
3
, SO
4
, OH , SCN and NO ,
3
and there was no influence by the subsequent addition of comp-
etent anions detected (Fig. 8).An absorption spectrum of chemo-
−
illustrated that chemosensor L binds with F as specific chemo-
−
sensor L with F at 561 nm was not influenced by addition of
sensor. Thus, chemosensor L could potentially be used as an
−
anion probe for monitoring F in physiological and environ-
0.7
–
mental systems.
L + anions
L + anions + F
1
−
0.6
0.5
H NMR titration of L with F : An interaction between
−
1
chemosensor L and F was further observed from H NMR
titrations in DMSO-d . The titrations were carried out by the
6
0.4
0.3
0.2
−
addition of F solution to chemosensor L in different equivalent
ratios and their NMR plots (Fig. 7) were collected. Upon the
−
1
addition of 0.2 equiv. of F to chemosensor L, H NMR chemical
shifts of the OH protons of chemosensor L at 10.18 and 15.28
completely disappeared. On the other hand, H NMR chemical
0.1
0
1
shifts of aromatic protons at 6.89-6.98, 7.16, 7.53, 8.27, 7.97-
–
F
–
Cl
–
2–
CO3
2–
SO4
–
–
–
I
OH
SCN NO3
8
.39 ppm and chemical shifts of CH=N proton at 9.23 ppm
–5
–
Fig. 8. Absorption intensity of L (2.5 × 10 M) in the presence of F (10.0
gradually shifted upfield after the additions of 0.2-1.0 equiv.,
equiv.) and additional other anions (50.0 equiv.) in CH CN solution
3

808 Nusuwan et al.
Asian J. Chem.
the studied anions. The miscellaneous competitive anions did
not lead to any significant spectral and colour changes. Thus,
chemosensor L can be used for the selective detection of F
geometry of chemosensore L showed effective binding site
2
+
(-OH and C=N groups). Binding between L-Cu was 2:1
−
−
complex and L-F was 1:2 corresponding to the laboratory
ions.
experiments.
Theoretical calculations: An optimized molecular
structure of the compounds were calculated by DFT calculations
Applications: The detection performance of proposed
2+
−
chemosensor (L) toward Cu and F was compared with the
previous studies as shown in Tables 1 and 2, respectively. A
developed chemosensor can potentially be applied to detect
[
19], which were carried out using the Gaussian 09 program.
The molecular geometries of the compounds were obtained
using DFT calculations with the B3LYP method using 6-31G
2+
Cu in various samples such as drinking water, seafood and
−
2+
−
(
d,p) for L-F complex and 6-311G (d,p) for L-Cu complex
some vegetables while F detection can also be in the samples
−
as the basis set. The optimized molecular structures of L-F
such as dental products, fruit juice and cooked food. Therefore,
a developed chemosensor (L) presents a number of attractive
analytical attributes such as high sensitivity, wide linear range
and good selectivity.
2+
complex and L-Cu complex are shown in Fig. 9. It was found
that binding energy of L-trans form lower than the L-cis form
indicated that former structure was more stable. Optimized
–
2+
Fig. 9. Opitmized geometry of L-F complex using the B3LYP/6-31G (d,p) level of theory (left) and L-Cu complex using the B3LYP/6-
311G (d,p) level of theory (right)
TABLE-1
COMPARISON OF DIFFERENT SENSORS FOR Cu(II)
Detection probes
Modes
Fluorescence (turn-off)
Fluorescence (turn-on)
Colorimetric
Linear range
0.65-8.57
0.05-4.50
–
LOD (µM)
0.65
0.018
10
Ref.
[[ 22 00 ]]
[[ 22 11 ]]
[[ 22 22 ]]
[[ 22 33 ]]
Fluorophore
Fluorophore
L-Cysteine-functionalized AuNPs
Azide- and alkynefunctionalized AuNPs
Colorimetric
–
50
4
-Mercaptobenzoic acid modified AgNPs
Colorimetric
Colorimetric
Colorimetric
Colorimetric
–
0.025
20
1.8
[[ 22 44 ]]
[[ 22 55 ]]
[[ 22 66 ]]
This work
DNA functionalized AuNPs
Azide functionalized AuNPs
Chromophore
20-100 µM
1.8-200.0 µM
1.2-19 µM
0.9
TABLE-2
COMPARISON OF DIFFERENT SENSORS FOR F
-
Detection probes
Thioglucose-AuNPs
CdSe/ZnS QDs
AuNP functionalization (agglomeration)
PAA-AuNPs
L-Cysteine-Ag-CdS/Ag-ZnS QDs
Hexametaphosphate-CdS QDs/Ca
CQDs
Chromophore
Modes
Colorimetric
Fluorescence (turn-on)
Colorimetric
Linear range
–
0.3-5.6 mM
–
LOD
20 mM
74 µM
120 µM
18 µM
5 µM
6 µM
6.6 µM
9.0 µM
References
[[ 22 77 ]]
[[ 22 88 ]]
[[ 22 99 ]]
[[ 33 00 ]]
[[ 33 11 ]]
[[ 33 22 ]]
[[ 33 33 ]]
This work
Colorimetric
–
Fluorescence (turn-on)
Fluorescent (turn-on)
Fluorescence (turn-on)
Colorimetric
0.01-1.20 mM
10-300 µM
6.6-56.6 µM
9.0-23.1 µM
2
+

Vol. 32, No. 4 (2020)
Dual Detection Highly Selective Colorimetric Chemosensors for Fluoride and Copper(II) Ions 809
1
2. C. Liu, J. Xu, F.Yang, W. Zhou, Z. Li, L. Wei and M.Yu, Sens. Actuators
B Chem., 212, 364 (2015);
Conclusion
In summary, a simple dual colorimetric chemosensor L
was successfully synthesized in high yields, which displays
high selectivity for detection of either copper ion in DMSO/
https://doi.org/10.1016/j.snb.2015.02.010
13. J. Shao, Dyes Pigments, 87, 272 (2010);
https://doi.org/10.1016/j.dyepig.2010.04.007
4. J. Huo, K. Liu, X. Zhao, X. Zhang and Y. Wang, Spectrochim. Acta A
Mol. Biomol.Spectrosc., 117, 789 (2014);
https://doi.org/10.1016/j.saa.2013.09.104
15. N. Dash, A. Malakar, M. Kumar, B.B. Mandal and G. Krishnamoorthy,
Sens. Actuators B Chem., 202, 1154 (2014);
https://doi.org/10.1016/j.snb.2014.06.047
6. G. Yang, K. Zhang, F. Gong, M. Liu, Z. Yang, J. Ma and S. Li, Sens.
Actuators B Chem., 155, 848 (2011);
1
H
2
O solution or fluoride ion in CH CN solution. The anion
3
recognition properties via hydrogen bonding interactions were
1
investigated by UV-visible and H NMR titrations and the
−
spectrum could be easily changed on with addition of F ions
through deprotonation. Meanwhile, a unique colour change
1
1
1
1
2
2
2
2
2
−
was observed from pale yellow to magenta with addition of F
3
ions in CH CN solution. Futhermore, chemosensor L can also
https://doi.org/10.1016/j.snb.2011.01.060
7. L.M. Zimmermann-Dimer and V.G. Machado, Dyes Pigments, 82, 187
form a complex with copper ions resulting in a colour change
from orange-red to yellow, Therefore, chemosensor L has a
(
2009);
https://doi.org/10.1016/j.dyepig.2008.12.013
8. X. Zhang, J. Fu, T.-G. Zhan, L. Dai,Y. Chen and X. Zhao, Tetrahedron
Lett., 54, 5039 (2013);
https://doi.org/10.1016/j.tetlet.2013.07.021
9. S. Jana, S. Dalapati, M.A. Alam and N. Guchhait, Spectrochim. Acta A
Mol. Biomol.Spectrosc., 92, 131 (2012);
2+
−
potential of application to detect Cu and F in various samples.
ACKNOWLEDGEMENTS
This work was supported financially by Srinakharinwirot
University research fund (No.021/2559).
https://doi.org/10.1016/j.saa.2012.02.028
0. P. Aussawaponpaisan, P. Nusuwan, P. Tongraung, P. Jittangprasert, K.
Pumsa-ard and M. Kuno, Mater. Today Proc., 4, 6022 (2017);
https://doi.org/10.1016/j.matpr.2017.06.089
CONFLICT OF INTEREST
1. C. Yu, L. Chen, J. Zhang, J. Li, P. Liu, W. Wang and B. Yan, Talanta,
The authors declare that there is no conflict of interests
regarding the publication of this article.
8
5, 1627 (2011);
https://doi.org/10.1016/j.talanta.2011.06.057
2. W. Yang, J.J. Gooding, Z. He, Q. Li and G. Chen, J. Nanosci.
Nanotechnol., 7, 712 (2007);
https://doi.org/10.1166/jnn.2007.116
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