A highly selective and sensitive chemosensor derived coumarin–thiazole for colorimetric and fluorimetric detection of CN?ion in DMSO and aqueous solution: synthesis, sensing ability, Pd(II)/Pt(II) complexes and theoretical studies

Article abstract of DOI:10.1016/j.tet.2016.08.004

A colorimetric and fluorescence turn-on cyanide probe, including coumarin–thiazole and imine (azomethine) group, has been designed and synthesized. It showed an immediate visible color change from yellow to deep red only in DMSO, and an appearance of strong yellow and green fluorescence when CN^?was added to DMSO, and a mixture of DMSO:H₂O (9:1), respectively. Thus, the sensor can be used to detect CN^?in aqueous solution. The sensing mechanism of chemosensor 4 reactions with CN^?ion was observed with the deprotonation and addition mechanisms at the same time. The mechanisms of reactions of chemosensor 4 with; CN^?, F^?, and AcO^?were examined using¹H NMR spectroscopy, and were also theoretically supported by DFT and TD-DFT calculations. In addition, the metal complexes of chemosensor 4 with Pd(II) and Pt(II) were also synthesized and all the synthesized compounds were characterized using general spectroscopic methods (FTIR,¹H/¹³C NMR, and mass spectrometry), magnetic susceptibilities, and conductivity measurements. Also, the molecular structure of 4 was determined using single crystal X-ray analysis.

Full text of DOI:10.1016/j.tet.2016.08.004

Accepted Manuscript
A highly selective and sensitive chemosensor derived coumarin-thiazole for
−
colorimetric and fluorimetric detection of CN ion in DMSO and aqueous solution:
synthesis, sensing ability, Pd(II)/Pt(II) complexes and theoretical studies
Ömer Şahin, Ümmühan Özmen Özdemir, Nurgül Seferoğlu, Burcu Aydıner, Musa
Sarı, Tuncay Tunç, Zeynel Seferoğlu
PII:
S0040-4020(16)30762-1
10.1016/j.tet.2016.08.004
TET 27985
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 26 April 2016
Revised Date: 12 July 2016
Accepted Date: 1 August 2016
Please cite this article as: Şahin E, Özdemir EE, Seferoğlu N, Aydıner B, Sarı M, Tunç T, Seferoğlu Z,
A highly selective and sensitive chemosensor derived coumarin-thiazole for colorimetric and fluorimetric
−
detection of CN ion in DMSO and aqueous solution: synthesis, sensing ability, Pd(II)/Pt(II) complexes
and theoretical studies, Tetrahedron (2016), doi: 10.1016/j.tet.2016.08.004.
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A highly selective and sensitive chemosensor derived
coumarin-thiazole for colorimetric and fluorimetric
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-
detection of CN ion in DMSO and aqueous solution:
Synthesis, sensing ability, Pd(II)/Pt(II) complexes
and theoretical studies
Ömer Şahin, Ümmühan Özmen Özdemir, Nurgül Seferoğlu, Burcu Aydıner, Musa Sarı, Tuncay Tunç
and Zeynel Seferoğlu

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1
Tetrahedron
journal homepage: www.elsevier.com
A highly selective and sensitive chemosensor derived coumarin-thiazole for
-
colorimetric and fluorimetric detection of CN ion in DMSO and aqueous
solution: Synthesis, sensing ability, Pd(II)/Pt(II) complexes and theoretical
studies
a
a
b
a
c
d
Ömer Şahin , Ümmühan Özmen Özdemir , Nurgül Seferoğlu , Burcu Aydıner , Musa Sarı , Tuncay Tunç
a
and Zeynel Seferoğlu*
a
Department of Chemistry, Faculty of Science, Gazi University, Teknikokullar, 06500 Ankara, Turkey
Department of Advanced Technology, Gazi University, Teknikokullar, 06500 Ankara, Turkey
b
c
Department of Physics, Faculty of Education, Gazi University, 06500 Ankara, Turkey
d
Department of Science Education, Aksaray University, 68100 Aksaray, Turkey
ARTICLE INFO
ABSTRACT
Article history:
Received
A colorimetric and fluorescence turn-on cyanide probe, including coumarin-thiazole and imine
(azomethine) group, has been designed and synthesized. It showed an immediate visible color
Received in revised form
Accepted
Available online
change from yellow to deep red only in DMSO, and an appearance of strong yellow and green
-
fluorescence when CN was added to DMSO, and a mixture of DMSO:H
2
O (9:1), respectively.
-
Thus, the sensor can be used to detect CN in aqueous solution. The sensing mechanism of
-
chemosensor 4 reactions with CN ion was observed with the deprotonation and addition
-
-
mechanisms at the same time. The mechanisms of reactions of chemosensor 4 with; CN , F and
-
1
AcO were examined using H NMR spectroscopy, and were also theoretically supported by DFT
and TD-DFT calculations. In addition , the metal complexes of chemosensor 4 with Pd(II) and
Pt(II) were also synthesized and all the synthesized compounds were characterized using general
Keywords:
1
13
Coumarin-thiazole
Schiff base
Anion detection
spectroscopic methods (FT-IR, H/ C NMR and mass spectrometry), magnetic susceptibilities, and
conductivity measurements. Also, the molecular structure of 4 was determined using single crystal
X-ray analysis.
Fluorescence turn-on probe
DFT, TD-DFT calculations
Pd(II)/Pt(II) complexes
2
009 Elsevier Ltd. All rights reserved.
1
.
Introduction
Recently, sensing, recognition and detection of analytes
with chemosensors have become a hot topic of interest in
host/guest and supramolecular chemistry. Anion sensing has
specially grown to be a major field in the last decades.
Therefore, the development of new chromogenic dye sensors
or receptors for selective determination of anions has become
attractive because of the importance of anions in
Amongs these anions, cyanide is the most significant to the
28
environment and human life because of its high toxicity.
Nevertheless the cyanide ion is vital as a raw material in
industrial processes such as electroplating, plastics
manufacturing, gold and silver extraction, tanning, and
metallurgy.
1-24
Hence, there is a strong need for efficient method that can
environmental, biological, and chemical processes.
It is
-
selectively recognize CN in real samples, especially in
widely known that anions like fluoride, acetate, cyanide,
chloride, iodide, and phosphate anions are significant in human
health. The fluoride, especially, is a biologically important ion
because of its role in the treament of dental cavities and
osteoporosis. However, excess fluoride can cause serious
aqueous and semi-aqueous media. Determination of anions can
be achieved by several methods including spectroscopic,
chromatographic, electrochemical and analytical techniques.
25
These are all costly and need sophisticated instrumentation.
25
Therefore, detection of anions with the use of simple
preparation and minimal instrumental assistance is desirable
for practical applications. Colorimetric and fluorimetric
chemosensors are important alternatives to the traditional
methods for determination of anions.
damage to the thyroid, bones, and the kidneys. The acetate
anion also plays a critical role in many metabolic processes,
and exhibits specific biochemical behavior on antibodies and
26,27
enzymes.
Until recently, several strategies for chemosensing, such as
deprotonation of the receptor part of the chemosensor,
nucleophilic addition reaction to carbonyl, imine, and iminium
∗
Corresponding author. Tel.: +90-312-202-1525; fax: +90-
3
12-212-2279; e-mail: znseferoglu@gazi.edu.tr

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2
Tetrahedron
bonds and the Michael acceptor carbon, hy
A
dro
C
ge
C
n-
E
bo
P
n
T
di
E
ngD MANth
U
iou
S
re
C
a,
R
a
I
n
P
d in the last step, 4 was synthesized by
T
interactions, and displacement approach to a coordination
condensation of 3, with 2-hydroxy-3-methoxybenzaldehyde in
a basic ethanol solution with excellent yield of 85%, as shown
in Scheme 1. The Pd(II) and Pt(II) complexes of 4 were
synthesized by using a well-known complexation procedure
between 4 and Pd(II)/Pt(II) (Scheme 1). Compound 4 and its
complexes were characterized using general spectroscopic
-
29,30
complex, have been designed for detection of CN .
Among
these approaches, the most important strategy for the detection
of cyanide is the nucleophilic addition approach, due to its
exceptionally high nucleophilicity, which is not observed for
other anions such as AcO and F . Also, these types of sensors
have several advantages such as being fast and more specific
-
- 30
1
13
methods (FT-IR, H/ C NMR and mass spectrometry), and
magnetic susceptibilities, and conductivity measurements
(Figs. S1-S4 in the Supplemenatry data). In addition, the
molecular structure of 4 was determined by single crystal X-
ray analysis (Fig.1 and Table 1 and Table S1 in the
Supplemenatry data). Suitable crystals of 4 used for X-ray
structural analysis were grown by slow evaporation in ethanol
solution. The crystallographic data collection and refinement
parameters are given in Table 1; selected bond lengths and
angles are listed in Table S1. ORTEP plot with atomic
numbering scheme is shown in Fig. 1. It was found to
crystallize in the orthorhombic, P21 21 21 space group, with
four molecules in the unit cell. The S1-C11 and S2-C12 bond
distances were found to be 1.703(3) and 1.750(3) Å,
respectively. The S-C bond distances were determined as
intermediate values between a single (1.82 Å) and a double
-
-
towards detection of CN , than interfering anions like AcO and
−
31
F .
Untill now, molecules have been synthesized for detection
-
of CN in organic, aqueous, and semi-aqueous media.
However, these synthesized chemosensors have some
disadvantages due to their complicated structures, hard
synthetic routes or troublesome purification processes, poor
yields, solubility problems in aqueous solution, and selectivity
Therefore, finding a simple receptor for
selectively sensing cyanide anion in aqueous medium is still a
challenge.
-
29,32
towards CN .
On the other hand, Schiff-bases can be candidates for
selective determination of CN in aqueous and semi-aqueous
media due to their easy synthetic procedures, good yields, high
purity or can easily be purified, and bearing an electrophilic
-
38d
bond (1.56 Å). This is an indication that there is some
electron delocalization in the thiazole ring. In addition, all
bond lengths and bond angles for 4 are consistent with those
found in related compounds (Table S1 in the Supplemenatry
2
9,33
imine carbon that can be used for addition reactions.
Schiff
bases, derived from aldehyde derivatives bearing a 2-hydroxy
group, are of great interest for detection of anions and cations
via hydrogen bond interactions or electrophilic addition to the
38d,39
data).
29,31-33
imine carbon.
However, these types of molecules using
-
The crystal structure shows intramolecular hydrogen
bonding between the phenolic oxygen and a hydrogen atom,
O(3)-H, of the salicylidene part, and also the amino nitrogen
atom, N(2) of the molecule. This plays important role in
as “turn on” chemosensors for detection of CN have been
rarely reported. This is because, these molecules bind by
stronger interactions between the metal ion and the Schiff base,
as compared to the hydrogen bonds or the nucleophilic
34
stabilizing the molecule. The chemosensor 4 has an
addition between the anion and the Schiff base. Beside using
these molecules as sensor complexes of Schiff bases, with
palladium (Pd) and platinium (Pt) as the central metals of the
complexes, show significant biological activity such as
intramolecular O-H…N hydrogen bonding [O3-H3'; 0.82,
H3'…N2; 1.84, N2…O3; 2.564(3) Å, O3–H3' …N2; 146.8°].
The ranges of the D–H…A angles and those of the H…A and
D…A distances indicate the presence of short hydrogen bonds
in the structure.
34-36
anticancer effects.
Due to the aforementioned properties,
Schiff bases and their metal complexes, therefore play
important roles in the life sciences and in the synthesis of
specially and fine chemicals. In addition, some of them are
also being investigated for their anti-carcinogenic, anti-
bacterial and anti-fungal effects, and can potentially be used as
37,38
anions and cations chemosensors.
In this paper, we report a
simple Schiff base chemosensor 4 which can selectively detect
-
-
−
CN , rather than interfering anions like AcO and F in aqueous
medium, via UV-vis, fluorimetric, and spectroscopic methods.
-
With appropriate analysis, it is possible to detect CN
separately in the same sample by “tuning” the solvent medium.
Also, we have synthesized and characterized Pd(II) and Pt(II)
complexes, of chemsosensor 4 for further potential application
as anticancer agents. Finally, all the experimentally obtained
results on the sensitivity and selectivity activities of the
chemosensor 4, and the mechanisms were also explained by
theoretical calculations.
Fig.1. The single crystal X-ray structure (left) and molecular
package diagram (right) of 4.
Schiff bases derived from 2-hydroxybenzaldehyde
derivatives can exhibit two tautomeric forms; enol-imine and
keto-amine. The Schiff base chemosensor 4 can show both
tautomeric forms, and exhibits two types of intramolecular
hydrogen bonding, which are O-H···N for the enol-imine form,
and N-H···O for the keto-amine form. Both forms of the
compound may affect the performance of chemosensor 4 and
the formation of its complexes. Therefore, before
determination of the chemosensing performance of
chemosensor 4, and its metal complexes formation properties,
2
.
Results and discussion
2
.1. Synthesis and characterization of Schiff base
In our study, a new multi-functional Schiff base based
chemosensor 4, (E)-3-(2-((2-hydroxy-3-
methoxybenzylidene)amino)thiazol-4-yl)-2H-chromen-2-one,
has been synthesized by two sequential steps; starting from 3-
(2-bromo)acetylcoumarin 2, followed by the preparation of its
thiazolylamine derivative 3, by condensation reaction with

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3
the most stable tautomeric form/forms of chem
A
os
C
en
C
so
E
r 4
P
m
T
u
E
stD MANch
U
em
S
o
C
sen
R
so
I
r
P
4
T
was observed at 345 nm in DMSO. This
be ascertained.
absorption band decreased gradually upon addition of 0.33
-
-
-
equiv of F , AcO and CN , to the solution of chemosensor 4
and a new absorption band at λ =507 nm was created.
However, other anions such as Cl , Br , I , H PO , HSO and
NO3 did not cause any significant color and UV–vis
absorption spectra changes (Fig. 2).
Results from X-ray structural analysis for chemosensor 4
show that, the hydrogen atom is observed as being attached to
the oxygen atom, and there is a hydrogen bonding between the
phenolic OH and the imine N. Therefore, chemosensor 4 is
more stable in the enol-imine tautomeric form in solid state.
Also, the phenolic proton belongs to the enol-imine tautomer,
max.
-
-
-
-
-
2
4
4
-
1
as observed at 11.25 ppm in H NMR spectra, in DMSO.
O
O
Br
2
CHO
O
O
EtOH
CH
3
CH2Br
+
Piperidine
Chloroform
O
OH
O
O
O
O
1
2
S
EtOH
H
2
N
NH
2
NH
S
2
N
CHO
EtOH
+
N
N
O
Piperidine
O
HO
OH
O
O
S
O
3
O
4
EtOH
MCl
2
N
S
N
O
O
O
O
M
S
O
O
O
O
N
N
M(L)
2
(
M: Pd, Pt L: 4)
Fig.2. UV-vis absorption spectral changes of chemosensor 4 (3.0
-
5
Scheme 1. Synthetic pathway of chemosensor 4 and its metal
x10 M) upon addition of 0.33 equiv of different anions in
DMSO. Inset shows the color change of vials.
complexes.
2
.2. Anion/cation sensing performance by UV-vis and
Fluorimetric titrations
The results from UV-vis titration showed that the
chemosensor 4 was more sensitive to CN , than F and AcO at
-
-
-
the stochiometric ratio of 1:0.33. The interaction mechanism
Chemosensing performance of chemosensor
4
was
-
-
-
between F , AcO and CN and chemosensor 4 could be
possibly explained by the hydrogen bonding ability and the
nucleophilic addition of the anions. The hydrogen bonding
investigated using UV-vis absorption and fluorescence
-
-
-
-
-
-
spectroscopy in DMSO against F , Cl , Br , I , AcO , CN ,
-
-
-
H PO , HSO and NO3 anions with tetrabutylammonium
-
2
4
4
ability of the anions is assumed to be in decreasing order: F
(
TBA) as the counter cation. The absorption maximum of
-
-
-
>
AcO > CN , based on their electronegativity. Thus, F and
-
AcO ions can better interact with chemosensor 4 only via
strong hydrogen bonding in DMSO, which eventually renders
the phenolic proton of chemosensor 4 deprotonate, thus
causing a bathochromic shift in the UV–vis spectra. This
bathochromic shift of the absorption band led us to propose the
change of intramolecular charge transfer (ICT) band through
Table 1. Crystal data and structure refinement details for 4.
Chemical formula
20 14 2 4
C H N O S
Formula weight
Temperature (K)
378.39
296(2)
Wavelength (Å)
0.71073
-
-
-
the deprotonation of chemosensor 4 by CN , F and AcO .
Following the identification of ICT of chemosensor 4, we
investigated its reversibility, an important feature of a
chemosensor. Systematic titration of chemosensor 4 in the
Crystal system, space group
Orthorhombic, P 21 21 21
(Å, º)
Unit cell dimensions:
a
b
c
4.9090(5)
17.0726(14)
20.9795(19)
1758.3(3)
4
0.214
1.429
784
-
3
presence of CN , upon addition of increasing amounts of TFA
Volume (Å )
(0−12 equiv) shifted the absorption band from 505 to 355 nm
Z
-
1
Absorbtion coefficient (mm )
Calculated density (Mg m )
F(000)
(Fig. S5 in the Supplemenatry data).
-
3
The sensing phenomena were also monitored by
fluorescence spectroscopy. As shown in Fig. 3, chemosensor 4
alone was essentially non-fluorescent. However, upon addition
Crystal size (mm)
Theta range for data
collection(º)
0.32x0.14x0.11
1.94-26.37
-
of CN , the emission intensity of the probe clearly increased at
Limiting indices
-6≤h≤6, -21≤k≤20, -15≤l≤26
-
5
71 nm (with a shoulder at 499 nm) with increasing CN
Reflections collected
Independent reflections
Number of reflections used
Number of parameters
Max. and min. transmission
Refinement method
Final R indices [I≥2σ(I)]
R indices (all data)
7536
3587
2405
concentration. The ‘switching-on’ of the emission, thus the
-
nucleophilic addition of CN to the imine functional group of
246
0.965, 0.977
chemosensor 4, 4–CN adduct, was obtained. The fluorescence
enhancement can be explained by intramolecular H-bonding
stabilization of a cyanohydrine type cyanide adduct, through
which ICT process can be blocked.
2
Ful-matrixleast-squares on F
= 0.0466, wR = 0.0932
= 0.0827,wR = 0.1092
1.025
0.227 and -0.177
R
1
2
R
1
2
2
Goodness -of- fit (GOF) on F
Largest difference in peak and
-
3
hole (e Å )

ACCEPTED MANUSCRIPT
4
Tetrahedron
ACCEPTED MANad
U
dit
S
io
C
n,
R
a
I
n
P
d deprotonation of phenolic hydrogen. The
T
observed bathochromic shift in UV-vis spectra (Fig.2), with
-
addition of CN to receptor in DMSO, is due to ICT after
deprotonation of the phenolic proton. However, the
significantly enhanced fluorescent intensity was probably
-
caused by the nucleophilic addition of CN to the imine
functional group of the chemosensor 4 to afford a chemosensor
4
–CN adduct (Scheme 2). This highly selective fluorimetric
detection of cyanide could be demonstrated even in the
presence of other anions in DMSO solution (Fig. S6 in the
Supplemenatry data). As a result, deprotonation of phenolic
-
proton and addition to the imine carbon with CN were
observed at same time. The proposed mechanisms on between
-
1
CN and chemosensor 4 were supported by the H NMR
titration studies and the theoretical obtained data from
DFT/TD-DFT calculation methods.
-
5
Fig.3. Fluorescence spectra of chemosensor 4 (1.0x10 M) in
-
-2
DMSO with different concentrations of CN (1.0x10 M) (0–14
equiv) in DMSO. The excitation wavelength was set at 345 nm.
Scheme 2. Proposed sensing mechanism of chemosensor 4 for the
-
-
-
-
-
-
-
detection of CN .
However, other anions, such as F , Cl , Br , I , AcO , H PO ,
2
4
-
-
HSO , and NO did not cause any significant changes in the
4
3
fluorescence emission intensity (Fig.4).
The interaction of 4 with the anions employed this study
can also be distinguished by the naked eye or by using a
portable UV lamp. Consistent with the change of UV–vis and
emission spectra, chemosensor 4 displayed a colour change
-
from yellow to deep red upon addition of CN . However, a
-
-
yellow-to-red color change was observed when F , AcO or
-
H PO , ions was added (Fig. 4). Thus it can serve as a
2
4
-
3
‘
‘naked-eye’’ probe for these anions in 1x10 M in DMSO
-
solution of 4. Upon addition of CN , the solution of 4 in
DMSO adduct displayed a strong yellow fluorescence.
However, the addition of the other anions to the solution of 4
in DMSO, showed no significant color or emission changes
either by the naked eye, or under a portable UV lamp.
Fig.4. Changes in the emission spectrum of chemosensor 4
-
5
(
1.0x10 M) upon addition of 14 equiv of different anions in
DMSO. Inset showing the color change under UV light, 365 nm.
-
-
-
CN is different from F and AcO when the receptor affinity
is taken into account. Cyanide has an almost equal split of its
negative charge at the N and C ends. The N terminus of
cyanide is a slightly stronger hydrogen bonding acceptor than
-
3
Fig.5. Photographs of chemosensor 4 (1x10 M in DMSO) upon
-
2
30
addition of 1 equiv studied anions (1x10 M in DMSO) under
ambient light (above), under UV light (below, 365 nm).
the C terminus, and it does not have spherical properties.
-
Furthermore, CN shows both basic and nucleophilic properties
toward the receptor part of any chemosensor. For example,
cyanide’s basicity has been utilized in its carbon-centered
complexation with some Lewis acid metal centers, and its
nucleophilicity has been employed in reversible C−C covalent
30
bond formation.
In this study, based on obtained UV–vis and fluorimetric
titration results, we propose that, the mechanism between 4
-
and CN occur via two separate processes; nucleophilic

ACCEPTED MANUSCRIPT
5
We carried out the sensing test of 4 to te
A
st
C
an
C
ion
E
s
PTE
heD MANUSCRIPT
in
t
present of water. Because the anion affinity may be changed if
same experiment is carried out in aqueous medium due to the
hydration of the anions. In this study, the detection of anions in
real samples was created by using DMSO/H O binary solution.
2
Indeed, when chemosensor 4 was treated with the some
-
-
-
selected anions, such as F , AcO and CN (14 equiv of each) in
DMSO/H O (9:1) binary solution, similar response was
2
obtained as of that in DMSO in the UV-vis and Fluorescence
-
spectrum (Figs. 6 and 7). Upon addition of CN to the receptor,
the absorption maximum of 4 shifted bathochromically to a
short wavelength (345 nm). This phenomenon was observed
-
only for upon CN addition. However, the new colour and
emission changes which can be observed by the naked-eye are
not the same as the previous ones because of the differences in
the solution environment. The chemosensor 4 displayed a
colour change from light yellow to dark yellow upon addition
-
of CN , whereas a yellow-to-orange colour change was
-
-
observed in the case of F and AcO (Fig. 6). Upon addition of
-
CN to the chemosensor in DMSO/H O (9:1), the emission
2
-
intensity of 4 increased at 531 nm with increasing CN
concentration. However, no significant emission change was
-
5
-
Fig.7. Changes in the emission spectrum of 4 (1.0x10 M in
observed under portable UV lamp upon addition of F and
-
-
-
DMSO/H O=9/1 (v/v)) upon addition of 14 equiv of CN , F and
2
AcO (Fig. 7 and 8). The spectrophotometric and fluorimetric
-
AcO in DMSO/H O (9:1, (v/v)). Inset showing the color change
2
titration results of 4 in DMSO/H O (9:1) binary solution
2
-
under UV light, 365 nm.
showed high selectivity for CN beside other interference
-
-
anions, especially F and AcO .
Chemosensor 4 contains –C=N- bond and can exhibit
cis/trans isomerism. Compounds bearing -C=N-, and -N=N-
chromophores, show isomerization, and are generally non-
fluorescent because they undergo decay processes in the
38d,40,41
excited states.
However, the fluorescence of their metal
complexes, containing a metal–nitrogen bond, increases
dramatically due to the inhibition of -C=N- isomerization. This
can be a good advantage for designing fluorescence “turn on”
metal chemosensor systems. In this study, due to the fact that
chemosensor 4 contains a phenolic oxygen, an imine N atom, a
thiazole N atom, and a lactone carbonyl oxygen on the
38d
coumarin ring of chemosensor 4, all of which can serve as
good ligands, we therefore evaluated chemosensor 4 affinity
towards some metal ions. The fluorimetric and colorimetric
sensing ability of 4 was studied in the presence of chloride
2+
2+
2+
2+
2+
salts of different cations such as Ca , Co , Cu , Hg , Mg ,
2+
2+
2+
2+
2+
2+
3+
Mn , Ni , Pd , Pt , Sn , Zn , and Al . Upon the addition
of 14 equiv of each of the cations, surprisingly all metal ions
showed either no or slight change in the absorption spectra
relative to the free chemosensor 4 in DMSO. However,
chemosensor 4 was sensitive to the metal ions after
deprotonation of the phenolic hydrogen by anions. It is
expected that in the molecular structure of 4, the deprotonated
phenolic oxygen has better donor ability than its neutral form.
This result is consistent with the literature results (Fig. S8 in
-
5
38d
Fig.6. UV-vis absorption spectral changes of 4 (3.0 x10 M) upon
the Supplemenatry data).
addition of 14 equiv of different anions in DMSO/H O (9:1). Inset
2
shows the color change of vials.
In the final experiment on spectrophotometric titrations, we
investigated the anion affinity to chemosensor 4 with respect to
change in DMSO/H O binary solution ratio. When the ratio of
2
DMSO/H O was changed from - DMSO/H O (9:1) to
2
2
-
DMSO/H O (1:9), interferences of F , and AcO anions were
2
-
not observed in UV-vis titration spectrum, but that of CN was
observed. This could arise from their higher solvation energies
-
-
or hydrogen bonding capability of F , and AcO or anions, than
-
that of CN , in water (Fig. S7 in the Supplemenatry data).

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solution of 4 was also titrated against up to 4
T
−
equiv of CN (Fig. 10). Within the addition of 0.2 equiv of
−
CN , the OH signal of 4 disappeared, and new signals began to
−
appear. Interestingly, after the first addition of CN , the imine
proton (Ha) began to shift downfield, its intensity decreased,
and more importantly a new peak appeared at 6.32 ppm, which
is consistent with the addition of cyanide to imine carbon
−
(
Ha’). Upon addition of 2 equiv of CN , the imine proton (Ha)
shifted from 9.36 to 9.12 ppm, which led to the appearance of
a new peak at 6.32 ppm, which also shifted to 5.91 ppm. After
this, the excess addition of CN did not produce any significant
−
-
5
Fig.8. Variation of fluorescence intensity of 4 (1.0x10 M) in the
presence of studied anions (14 equiv) in DMSO (left) and in the
change in the spectra for Ha’.
-
-
-
presence of F , AcO and CN (14 equiv) in DMSO/H O (9:1, v/v)
2
(
right).
1
2
.3. H NMR titration experiment
In order to clarify the mechanism of the host-guest
−
−
− 1
interaction between 4 and F , AcO and CN , H NMR titration
of 4 in the absence and presence of different equivalents of
−
relevant the anions in DMSO-d were performed. While F ,
6
−
and AcO gave almost the same response when titrated against
, CN responded differently. DMSO-d solution of 4 was also
−
4
6
-
-
titrated against F , and AcO , for up to 4 equiv of each of the
anions (Fig. 9, Fig. S9 in the Supplemenatry data). When 1
equiv of each of the anions was added to 4, the OH signal
disappeared, slight upfield shifts of imine (Ha) and thiazole
(He) protons were observed, and significant upfield shifts of
phenyl protons (Hb, Hc and Hd) were also observed. This
−
indicates the deprotonation of the OH proton that causes the
change of the electron distribution in the conjugated system.
As was expected, no significant change was observed at
coumarin ring signals. After addition of 4 equiv of each of the
anions, Further addition of the anions did not produce any
significant changes in the spectra, except the addition of
fluoride, which led to the appearance of a new peak, as a
1
Fig.10. Partial H NMR (300 MHz) spectra obtained via titrations
-
2
of 4 (1x10 M) with different amounts of TBACN solution (1 M)
in DMSO-d
.
6
triplet, at 16.15 ppm (114.7 Hz), indicating the formation of
−
[
HF ] species.
Similar to the fluoride and acetat titration, the thiazole (He)
proton and phenyl protons (Hb, Hc and Hd) were shifted
upfield. Interestingly, while the intensity of (Hf) signal on the
coumarin ring at 8.88 ppm decreased, a new proton (Hf’)
signal at 8.69 was observed. A similar phenomenon was
observed at other coumarin proton signals. In addition, N-H
proton were not observed in the spectra because of its
exchange ability with DMSO. All the observed differences on
the proton signals of 4-CN adduct, suggest to us that, two
different mechanisms (deprotonation and addition) occur at the
same time in NMR titration, but at the end of the titration, the
major product was produced by the nucleophilic addition
2
-
reaction of CN to the imine carbon, which generated a
cyanohydrin type compound in the NMR spectrum.
2
.4. Theoretical calculations for sensing mechanism
- - -
of the three analytes; F , AcO and CN
1
Fig.9. Partial H NMR (300 MHz) spectra obtained via titrations
Furthermore, to support the experimental results, we carried
out density functional theory (DFT) calculations. The reason
for doing the DFT calculations was also to optimize the
-
2
of 4 (1x10 M) with different amounts of TBAF solution (1 M) in
DMSO-d6.
-
-
-
structures of 4, 4-F , 4-AcO , and 4-CN at the B3LYP/6-
1+G(d,p) level, using the Gaussian 09 program. The
geometry of 4 was optimized from its X-ray structures. The
3

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-
-
-
optimized structures of 4, 4-F , 4-AcO ,
A
andCC4-
E
CNPT
a
E
reD MANth
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e a
S
bs
C
or
R
pt
I
io
P
n
T
wavelength. However, as seen from Table 1,
illustrated in Fig.11. The chemosensor 4 was found to be
completely planar, and all the angles between the coumarin
and thiazole moieties, as well as between the phenol moiety
the obvious red shift in the absorption maxima was observed
-
-
-
upon the interaction of F , AcO and CN with 4.
o
and the rest of the molecule, being the same (i.e. 0.0 ). Due to
-
the planar conformation, the π-conjugation was provided and
Table 2. Selected parameters for the vertical excitation of 4, 4-F ,
4-AcO and 4-CN based on the optimized ground state
geometries.
-
-
the ICT transition occurred from the phenolic moiety to
-
-
-
thiazole moiety. In the case of 4-F , 4-AcO , and 4-CN , only
changes in the angle between the coumarin and thiazole
o
o
λmax
(nm)
322
Oscillator
Strength, f
Major cont.
moieties, in the range, -2.44 to -4.47 , were obtained. These
small differences in the structures should be responsible for a
red shift in the absorption spectrum and existence of ICT
-
4
4
4
4
4
0.4912
0.3143
0.3999
0.3244
0.4086
0.2201
0.4480
0.2693
0.2224
0.3192
0.2409
HOMO-2→LUMO (90%)
HOMO-1→LUMO (89%)
HOMO→LUMO+1 (95%)
HOMO-2→LUMO (95%)
HOMO→LUMO+1 (96%)
HOMO-2→LUMO (65%)
HOMO→LUMO+1 (96%)
HOMO-2→LUMO (87%)
HOMO→LUMO (98%)
HOMO-2→LUMO (74%)
process. On the other hand, when CN was induced through a
3
99
458
23
461
25
465
23
nucleophilic addition mechanism, the planarity of the phenol
with the rest of the molecule was inhibited with the dihedral
-
-F
3
o
angle at -20.1 (Fig.11e).
-
-AcO
3
-
-CN
3
-
-CN * 519
3
3
33
23
HOMO→LUMO+1 (67%)
-
*
denotes the nucleophilic addition mechanism for CN .
The molecular orbitals that are relevant to the excitations
are given in Fig.12. For 4, the HOMO-1 is delocalized over the
whole of the main skeleton of 4, while the contribution of the
thiazole moiety is partially visible in the HOMO-2. The
LUMO of 4 is localized on the phenol and thiazole moieties.
-
-
-
When 4 was interacted with the F , AcO , and CN anions via
the deprotonation process, the HOMO was delocalized over
the phenol and the neighboring thiazole moiety. However, the
LUMO involved the coumarin and some contributions from
the thiazole moiety, while the LUMO+1 was localized on the
phenol and thiazole moieties. On the other hand, the LUMO
and LUMO+1 are contributed to by the coumarin and also
sligthly by the thiazole moiety. These results indicate clearly
that, the ICT transition continued from phenolic moiety to the
thiazole moiety, after the deprotonation process. The full
involvement of the thiazole moiety and the imine bridge are
-
seen in the HOMO after the interaction between 4 and CN ,
due to the nucleophilic addition. As was expected, it is clear
that the ICT process was blocked due to conjugation break
between the phenolic, and the thiazole-coumarin moieties,
which can be the main reason for the fluorescence
-
enhancement of 4-CN , adduct due to the nucleophilic addition
to the imine bridge.
-
-
Fig.11. The optimized structures of a) 4, b) 4-F , c) 4-AcO , d) 4-
-
-
CN (for the deprotonation mechanism), e) 4-CN (for the
nucleophilic addition mechanism).
Hence the π-conjugation between the phenolic and thiazole-
coumarin moieties was interrupted. As a result of the
interruption of the π-conjugation, there could be a blocking
ICT process relative to 4. To gain an insight into the sensing
-
-
-
mechanism of the F , AcO and CN complexes of 4, time-
dependent density functional theory (TD-DFT) calculations
were performed at the optimized geometries. For 4, there were
two peaks in its absorption spectrum at 322 nm and 399 nm
due to the transition of HOMO-2→LUMO (90%) and HOMO-
1
→LUMO (89%), respectively (Table 1). The transition
HOMO-2→ LUMO (90%) with the oscillator strength
f=0.4912 of 4 was in consistent with the experimental value of

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the imine ν(CH=N) band, which occurred at
-
1
-1
567 cm in the chemosensor 4 by approximately 30 cm after
complexation, indicating that there is a coordination between
45
the imine nitrogen atom and a metal ion (N→M). The second
feature is the disappearance of the phenolic ν(OH) band, which
-
1
occurred at 3435 cm in the free chemosensor 4, and in all the
complexes, which also indicates that there is a coordination
between the metal ion and the phenolic oxygen, after
46
deprotonation. This result is further supported by the shift of
-
1
ν(C–O) to 1256 cm (compared to that of the chemosensor 4)
-
1
-1
which were observed at 1248 cm and 1246 cm , after
complexation. The participation of oxygen and nitrogen atoms
in coordination with the metal ion is further supported by the
appearance of new bands within the ranges (550–600), (425–
-
1
47
5
30) cm due to ꢀM-O and ꢀM-N, respectively. However the
stretching vibrations, of the carbonyl group v(C=O), and
vasym(C-O-C) of the lactone ring in the spectra of 4, remained
almost the same after complexation, and thus the lactone
oxygen is not involved in chelate formation.
2
.7. Mass spectra
-
-
The mass spectral decomposition modes of thiazole
compounds containing various coumarin derivatives have been
investigated and fragmentation pathways have been
Fig.12. Selected molecular orbitals for a) 4, b) 4-F , c) 4-AcO , d)
-
-
-
4
-CN (for the deprotonation mechanism for CN ), e) 4-CN (for
-
the nucleophilic addition mechanism for CN ).
48
suggested. The electron impact mass spectrum of the Pd(II)
and Pt(II) complexes were recorded at 70 eV. Both complexes
+
have molecular ion peak, [M+Na] at m/z (intensity %) 884
2
.5. Pd(II)/Pt(II) complexes of chemosensor 4
+
(
[
30%), and at 975 (15%) corresponding to [PdL +Na] and
2
+
PtL +Na] and fragmentation routes as shown in Scheme 3.
2
The first fragmentation peak in the mass spectrum of the
PdL ] complex is traced by a peak at m/z 662 (17%) owing to
Recently, Schiff base based metal complexes are well-
known and most popular to target cancer treatments due to
easily synthesize and coordinate with Pd(II) and Pt(II).
[
2
42-44
elimination of coumarin, (C H O ) and C H moieties from the
9 5 2 2 4
Pd(II) complex. Then, the other fragments after the separation
of the phenol derivative (C H O ) and CNS groups from the
In our study, synthesized Schiff base 4 can be potential
ligand for obtaning metal complexes with Pd(II) and Pt(II)
because of bearing the phenolic oxygen, the imine and thiazole
N atoms, and the lactone carbonyl oxygen on the coumarin
part. As was expected, Pd(II) and Pt(II) complexes of 4 were
synthesized using general complexation methods, were also
and characterized (Scheme 1). The complexes are stable in air
as solids, and are soluble in DMSO. They are slightly soluble
in alcohol, but insoluble in water. The melting points of the
7
4
2
Pd(II) complex, were observed at m/z 500 (19 %). Finally, the
fragment corresponding to ligand (4), after removing metal and
the NH group occurred at m/z 379 (100 %) as the main peaks.
2
In addition, for the [Pt(L) ] complex; the first fragment is
2
traced by a peak at m/z 929 (16%) owing to elimination of
carbonyl (CO) and methyl (CH ) moieties. Then, the other
3
fragments with the separation of the ligand (L) and methyl
(CH ) groups from the Pt(II) complex were observed at m/z
3
o
prepared metal(II) complexes are higher than 250 C. The
557 (100 %) as the main peak. Finally, the fragment
corresponding to ligand, after removing metal occurred at m/z
379 (63 %) (Figs S12 and S13 in the Supplemenatry data).
observed lower molar conductivity value for the metal
complexes revealed their non-electrolytic nature. Thus, the
general formula of the complexes is [ML ], where M = Pd or
2
Pt, and L = Potential ligand.
2
.6. FT-IR Spectra
The FT-IR Spectra of 4 (Fig.S1 in the Supplemenatry data)
and its metal complexes (Fig.S10 and S11 in the
Supplemenatry data) were recorded in KBr pellets. Significant
frequencies were selected by comparing the IR spectra of the
ligands with those of the metal complexes. The free ligands
-
1
-1
displayed stretching bands at 1722 cm , 1567 cm , and 1256
-
1
cm , which are assigned to v(C=O lactone), v(CH=N), and
phenolic v(C-O), respectively. In addition, the band at 1178
-
1
cm is due to v
(C-O-C) of the lactone ring. There are some
asym
specific features which belong to specific complexes in the IR
spectra. The first feature is the lowering shift of the stretching

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experimental data and the proposed sensing
mechanisms. Thus, this chemosensor exhibits a new method of
−
−
−
simultaneously assaying F , AcO , and CN by two different
detection modes. The results obtained from the experimental
and theoretical studies showed that Chemosensor 4 is highly
−
selective in both colorimetric and fluorimetric response to CN
based on a deprotonation process and a nucleophilic addition,
both in DMSO and DMSO/H O binary solution. The detection
2
−
of CN by 4 was found to be free of interference from any of
the other anions such as F and AcO in aqueous solution. The
interaction of CN with 4 enhances the fluorescence emission
−
−
−
and induces a turn on response in the electronic and
fluorescence spectra in the visible region. Thus, these receptors
can be used as dual probes for naked-eye detection through
change in colour and fluorescence. In addition, metal
complexes of 4 with Pd(II) and Pt(II) were synthesized and
characterized using general spectroscopic methods (FT-IR and
mass spectrometry), magnetic susceptibilities, and conductivity
measurements. In our future study, the anticancer activity of
the prepared compounds and their derivatives (Ligand and its
metal complexes) will be evaluated on some human cancer cell
lines.
4
.
Experimental
4
.1. Materials, instrumentation and methods
The chemicals used in the syntheses of all compounds,
including palladium and platinium chloride, were obtained
from Aldrich Chemical Company (USA) and were used
without further purification. All solvents used were of
analytical grade. The solvents were dried according to standard
procedures. All reactions were magnetically stirred and
monitored by thin layer chromatography (TLC), using Merck
silica gel (60 F254) plates (0.25 mm) and visualized under
Ultraviolet light. FT-IR spectra were recorded on a Mattson
Scheme 3. Fragmentation of Pd(II) and Pt(II) complexes.
2
.8. Electronic spectra and magnetic behavior
The electronic spectra of 4 and its Pd(II)/Pt(II) complexes
-
3
were studied in 1x10 M DMSO solutions. The free ligand
exhibited two bands at 345 and 360 nm assigned to π→π* and
n→π* transitions, respectively. The electronic spectrum of the
1
000 FT-IR spectrophotometer (Gazi University Department
-1 1 13
of Chemistry, Turkey) in KBr (ν, in cm ). H NMR and
C
[
ML ] complex obtained showed an additional band at 420-440
2
1 1
spectra were recorded on a Bruker Ultrashield 300 MHz NMR
spectrometer (Gazi University, Department of Chemistry,
nm, corresponding to the allowed spin A → B transition
1g
1g
which is in consistent with the square planar geometry of the
complex. Pd(II) and Pt(II) complexes show bands in the range
of 420-498 nm. Hence, the square-planar structures may be
Turkey) in DMSO-d . Chemical shifts are expressed in δ units
6
(ppm) with tetramethylsilane (TMS) as the internal reference.
49
Coupling constant (J) are given in hertz (Hz). Signals are
abbreviated as follows: singlet, s; doublet, d; doublet-doublet,
dd; triplet, t; multiplet, m. Ultraviolet-visible (UV-vis)
absorption spectra were recorded on an AnalytikjenaSpecord
assigned to these complexes. The magnetic moments of the
complexes (as B.M.) were measured at room temperature.
They have diamagnetic character, and therefore the complexes
have square planar geometry.
2
00 Spectrophotometer (Gazi University, Department of
Chemistry, Turkey) at the wavelength of maximum absorption
λmax, in nm). Fluorescence spectra were recorded on
(
3
.
Conclusions
HITACHI F-7000 FL Spectrofluorophotometer in the range of
the same solvents with a slit width of 2.5 nm used for both
excitation and emission. All melting points are uncorrected and
We have developed an exclusive single chemosensor 4,
o
in degrees celsius ( C) (Electrothermal 9200 melting point
based on a Schiff base bearing a coumarin and thiazole
apparatus). Mass spectra were recorded using a Waters LCT
Premier XE (LC-MS) (Ankara University, Laboratories,
Department of Pharmacological Sciences, Turkey) mass
spectrometer. The molar magnetic susceptibilities were
measured on powdered samples using Gouy method. The
molar conductance measurements were carried out using a
Siemens WPA CM 35 conductometer.
−
−
heterocycle rings in the same framework, for F , AcO and
−
CN through different signaling mechanism. Chemosensor 4
was characterized using general spectroscopic methods (FT-
1
13
IR, H/ C NMR and mass spectrometry) and its molecular
structure was determined by single crystal X-ray analysis. The
selectivity and sensitivity mechanism towards the anions were
demonstrated using techniques such as fluorescence,
1
absorption, and H NMR spectroscopy, and visual fluorescence
color changes. Moreover, DFT and TD-DFT studies results

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-
5
4
.2. Synthetic procedures
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f 3x10 M of Chemosensor 4 was obtained (For
-5
fluorimetric titration, the final concentration was 1x10 M). 2
-
2
µL-40 µL of the salts of TBA solution (1x10 M) were
-
5
3
-(2-bromoacetyl)coumarin
(2)
and
2-Amino-4-(3-
transferred to the solution of each Chemosensor (3x10 M)
prepared above, into the glass cell. After mixing them for a
few seconds, UV–vis absorption spectra were taken at room
coumarinyl)thiazole (3) were synthesized using literature
50
methods.
o
-
-
-
-
-
-
temperature (25 C). TBA salts of F , Cl , Br , I , AcO , CN ,
Synthesis
of
(E)-3-(2-(2-hydroxy-3-
methoxybenzylidene)amino)thiazol-4-yl)-2H-chromen-2-one
4)
-
-
-
-2
H PO , HSO and NO (1x10 M) were dissolved in DMSO
2
4
4
3
(1 mL).
(
In all experiments, any changes in the UV-vis and emission
spectra of 4 were recorded upon the addition of TBA salts
-
3
To a mixture of compound 3 (1.5x10 mol, 0.37 g) and 2-
-
3
hydroxy-3-methoxybenzaldehyde (1.5x10 mol, 0.23 g) in dry
EtOH (30 mL), 2-3 drops of piperidine were added. The
reaction mixture was refluxed for 5 hours. After the
completion of the reaction, the solvent was evaporated and the
orange solid precipitate was filtered through suction, washed
with pure water and thereafter washed several times with
EtOH and dried in air. The orange microcrystals products were
obtained from ethanol-acetic acid mixture in 85% yield (0.48
-5
while the ligand concentration was maintained at 3x10 M (for
UV-vis titration) and 1x10 M (for Fluorimetric titration).
-5
1
For H NMR titration experiment;
1
o
-1
For H NMR titrations, two stock solutions were prepared
g); m.p: 201 C; FT-IR (KBr, ν , cm ): 3435 (O-H), 3040
Aromatic C-H), 2928 (Aliphatic C-H), 1722 (C=O, lactone),
-2
max
in DMSO-d , one containing the sensor (1x10 M) only, and
6
(
1
the another containing an appropriate concentration of each of
the following anions, F , AcO and CN (1 M). Aliquots of the
two solutions were mixed directly in NMR tubes. The NMR
1
3
1
7
597 (C=C), 1567 (C=N), 1256 (C-O); H NMR (DMSO-d ,
−
−
−
6
00 MHz) δ: 11.25 (s, 1H); 9.39 (s, 1H); 8.88 (s; 1H); 8.37 (s,
H); 7.98 (dd, J: 1.3, 7.8 Hz, 1H); 7.66 (dt, J: 1.5, 8.5 Hz, 1H);
.47 (d, J:6.6, 1H); 7.41 (t, J:7.7, 1H); 7.36 (s, 1H); 7.23 (dd,
o
sample temperature was kept constant at 25 C.
13
J:1.3, 8.1, 1H); 6.69 (t, J:8.0, 1H); 3.85 (s, 3H); CNMR
DMSO-d , 75 MHz) δ: 170.8; 164.9; 159.3; 153.0; 150.7;
(
6
4
.5. Computational Procedures
1
1
3
48.6; 146.2; 140.3; 132.6; 129.7; 125.3;122.6; 120.5; 120.2;
+
19.9; 119.7; 119.6; 117.1; 116.4; 56.4; LCMS ES , m/z =
+
79.21, [M + H] , calc. for C H N O S = 378.07.
20
14
2
4
Calculations were carried out using the Gaussian 09
program. Geometry optimization of the title compound was
performed by using DFT method with Becke’s three
parameters hybrid exchange-correlation function (B3LYP) at
-31+G(d,p) basis set. The vibrational analysis was performed
54
4
.3. X-ray structure determination of 4
5
5
6
using the same method to verify that the optimized structures
correspond to local minima on the energy surface. Absorption
spectra were computed as vertical electronic excitations from
the ground-state minima by using the time-dependent density
functional theory (TD-DFT) at the same level in DMSO using
the polarized continuum model (PCM). The absorption
maxima and oscillator strengths were obtained for the lowest
10 singlet-singlet transitions.
Crystallographic data of the compounds were recorded on a
Bruker Kappa APEX II CCD area-dedector X-ray
diffractometer, employing plane graphite monochromatized
with MoK radiation (λ=0.71073 Å), using ω-2θ scan mode.
α
The structures were determined by the direct methods and
56
2
refined by full-matrix least-squares techniques on F using the
solution program SHELXS-97 and refined using SHELXL-
51
9
7. The empirical absorption corrections were applied by
52
multi-scan via Bruker, SADABS software. Hydrogen atoms
of the hydroxy molecules were located in difference Fourier
syntheses, with distances of O-H= 0.82 Å. The remaining
hydrogen atoms were placed geometrically at distances of
4
.6. Synthesis of Pd(II) and Pt(II) complexes
0
.93-0.96 Å from their parent atoms for C-H bonds. The
-
3
To a hot solution (1x10 mol) of 4 in ethanol (30 mL), a hot
molecular structure plots were prepared using ORTEP-3 for
Windows.
53
solution of corresponding metal chlorides [Na PdCl and
K PtCl ] (5x10 mmol, in 2 mL water) were added slowly in
2
4
-
4
2
4
the molar ratio 1:2 (M:L) in the presence of few drops of
NaOH as basic medium. The resulting mixtures were stirred
and refluxed on a hot plate for 48 h and then concentrated to a
small volume. The solid complexes formed were collected by
filtration, washed with a small volume of ethanol, water and
4
.4. UV–vis and fluorimetric measurements of
receptor 4 with all studied anions
o
ether, and were then left in glass oven at 150 C for 2 h in
vacuo, to prevent hydration, and dried in desiccators over
For UV–vis and Fluorimetric titration experiments;
Chemosensor 4 (0.0037 mg, 1x10 mol) was dissolved in
-
5
-
2
-2
CaCl
complexes). PdL
H), 2925 (Aliphatic C-H), 1717 (C=O, lactone), 1605 (C=C),
. Yields: 42% (for Pd(II) complexes), and 60% (for Pt(II)
2
-1
DMSO (1 mL, 1x10 M), and 1x10 M of 4 was diluted to
-
3
: FT-IR (KBr, νmax, cm ): 3042 (Aromatic C-
2
1
x10 M. Tetrabutylammonium (TBA) salts of each of the
-2
anions (TBAX) (1 mol) was dissolved in DMSO (1 mL, 1x10
M). A solution containing 60 µL of Chemosensor 4 and 1940
µL of DMSO (For fluorimetric titration; 20 µL of
-1
1
536 (C=N), 1248(C-O). PtL : FT-IR (KBr, ν , cm ): 3041
2 max
(Aromatic C-H), 2925 (Aliphatic C-H), 1716 (C=O, lactone),
-
3
1603 (C=C), 1540 (C=N), 1246 (C-O).
Chemosensor 4 (1x10 M) and 1980 µL DMSO were taken),
was prepared and transferred into a glass cell and a final

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7. Shao, J.; Lin, H.; Yu, M.; Cai, Z.; Lin, H. Talanta 2008, 75,
Acknowledgements
ACCEPTED MANUSCRIPT
551-555.
2
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We thank the Scientific and Technological Research Council
of Turkey TUBITAK [Project no. 214Z152] for financial
support. We are also thankful to Aksaray University of Science
and Technology Application and Research Center, for the use
of the Bruker SMART BREEZE CCD diffractometer
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Supplementary data
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Original FT-IR, H NMR, C NMR and LCMS spectra,
figures belong to chemosensor 4 and its complexes can be
found, in the online version, at….

ACCEPTED MANUSCRIPT
ACCEPTED MANUSCRIPT
Highlights
•
A coumarin-thiazole based schiff base scaffold was employed to create colorimetric
-
and turn-on fluorescence ratiometric CN probe for the first time in DMSO and
aqueous solution.
-
•
•
The chemosensor can be successfully used as turn-on fluorescence CN probe in
DMSO and aqueous solution.
The deprotonation and nucleophilic addition mechanisms between the anions and
1
chemosensor was clearly confirmed by H NMR spectroscopy and theoretical
calculations.
•
Pd(II) and Pt(II) complexes of chemosensor were also synthesized and characterized
for further potential application as anticancer agent.