Coumarin-indole conjugate donor-acceptor system: Synthesis, photophysical properties, anion sensing ability, theoretical and biological activity studies of two coumarin-indole based push-pull dyes

Article abstract of DOI:10.1016/j.molstruc.2017.06.079

Two coumarin-indole conjugate fluorescent dyes having donor-acceptor-donor (D-A-D) (CI-1 and CI-2) were synthesized, and characterized using IR, ¹H/¹³C NMR and HRMS. The absorption and emission properties of the dyes were determined in different solvents. The anion sensitivity and selectivity of the dyes were studied with some anions (CN^?, F^?, AcO^?, Cl^?, Br^?, I^?, HSO₄^? and H₂PO₄^?) in DMSO, and their interaction mechanisms were evaluated by spectrophotometric and ¹H NMR titration techniques. In addition, the molecular and electronic structures of CI-1, as well as the molecular complexes of CI-1, formed with the anions (F^? and AcO^?), were obtained theoretically and confirmed by DFT and TD-DFT calculations. CI-1 behaves as a colorimetric chemosensor for selective and sensitive detection of CN^? in DMSO/H₂O (9:1) over other competing anions such as F^? and AcO^?. However, only CN^? interacts with chromophore CI-2 via Michael addition and the main absorption maxima shifts hypsochromically with an observed distinctive color change from orange to yellow. For using as a optic dye, the thermal stability properties of the dyes was determined by TGA (Thermal Gravimetric Analysis). Antimicrobial, antifungal and DNA-ligand interaction studies of the dyes were also examined. The dyes cause conformational changes on DNA and selectively bind to nucleotides of A/A and G/G.

Full text of DOI:10.1016/j.molstruc.2017.06.079

Accepted Manuscript
Coumarin-indole conjugate donor-acceptor system: Synthesis, photophysical
properties, anion sensing ability, theoretical and biological activity studies of two
coumarin-indole based push-pull dyes
Tuğçe Aksungur, Burcu Aydıner, Nurgül Seferoğlu, Müjgan Özkütük, Leyla Arslan,
Yasemin Reis, Leyla Açık, Zeynel Seferoğlu
PII:
S0022-2860(17)30860-8
10.1016/j.molstruc.2017.06.079
MOLSTR 23965
DOI:
Reference:
To appear in: Journal of Molecular Structure
Received Date: 12 May 2017
Revised Date: 15 June 2017
Accepted Date: 17 June 2017
Please cite this article as: Tuğç. Aksungur, B. Aydıner, Nurgü. Seferoğlu, Mü. Özkütük, L. Arslan, Y.
Reis, L. Açık, Z. Seferoğlu, Coumarin-indole conjugate donor-acceptor system: Synthesis, photophysical
properties, anion sensing ability, theoretical and biological activity studies of two coumarin-indole based
push-pull dyes, Journal of Molecular Structure (2017), doi: 10.1016/j.molstruc.2017.06.079.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
Coumarin-indole conjugate donor-acceptor system:
Synthesis, photophysical properties, anion sensing ability,
theoretical and biological activity studies of two coumarin-
indole based push-pull dyes
a
a
b
c
d
Tuğçe Aksungur , Burcu Aydıner , Nurgül Seferoğlu , Müjgan Özkütük , Leyla Arslan ,
d
d
a,
Yasemin Reis , Leyla Açık and Zeynel Seferoğlu *
a
Gazi University, Department of Chemistry, 06500 Ankara, Turkey
b
Gazi University, Advanced Technology Department, Inst. Sci. &Technol., Ankara, Turkey
c
Eskişehir Osmangazi University, Department of Chemistry, 26480 Eskişehir, Turkey
d
Gazi University, Department of Biology, 06500 Ankara, Turkey
Abstract
Two coumarin-indole conjugate fluorescent dyes having donor-acceptor-donor (D-A-D) (CI-
1
13
1
and CI-2) were synthesized, and characterized using IR, H/ C NMR and HRMS. The
absorption and emission properties of the dyes were determined in different solvents. The
−
−
−
anion sensivity and selectivity of the dyes were studied with some anions (CN , F , AcO ,
−
−
−
−
−
4
Cl , Br , I , HSO and H PO ) in DMSO, and their interaction mechanisms were evaluated
4
2
1
by spectrophotometric and H NMR titration techniques. In addition, the molecular and
electronic structures of CI-1, as well as the molecular complexes of CI-1, formed with the
−
−
anions (F and AcO ), were obtained theoretically and confirmed by DFT and TD-DFT
calculations. CI-1 behaves as a colorimetric chemosensor for selective and sensitive detection
−
−
−
of CN in DMSO/H O (9:1) over other competing anions such as F and AcO . However,
2
1

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−
only CN interacts with chromophore CI-2 via Michael addition and the main absorption
maxima shifts hypsochromically with an observed distinctive color change from orange to
yellow. For using as a optic dye, the thermal stability properties of the dyes was determined
by TGA (Thermal Gravimetric Analysis). Antimicrobial, antifungal and DNA-ligand
interaction studies of the dyes were also examined. The dyes cause conformational changes
on DNA and selectively bind to nucleotides of A/A and G/G.
−
Keywords: Coumarin-indole conjugate, push-pull dye, selective CN detection, NLO, DFT,
TD-DFT, Biological activity.
*
*
Corresponding authors Tel.: +90 312 2021525; fax: +90 312 2122279
E-mail addresses: znseferoglu@gazi.edu.tr (Z. Seferoğlu).
1
. Introduction
Compounds containing coumarin core represent one of the most important chemical classes of
organic fluorescent materials [1]. Many dyes, based on coumarin ring system, have been
particularly used in the field of medical diagnostic [2], optoelectronics [3–5], optical
whitening [6], cellular imaging [7], fluorescent probes for proteins, amino acids, and for
sensing anions/cations [8-14].
Recently, many organic dyes having absorption and emission in the near infrared (NIR)
region have attracted continuous attention due to their various applications in biological
system, advanced materials and their related fields [15-19]. Some of their advantages include
minimal interfering absorption and fluorescence in biological samples, inexpensive laser
diode excitation, reduced scattering and enhanced tissue penetration depth. Electron donating
2

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and accepting groups attached in a fluorophore or chromophore can affect optical responses,
corresponding shifts of absorption and emission maxima, or fluorescence quantum yields.
Generally, the some of fluorescent coumarin derivatives show absorption in the UV region
and emit blue light however, the coumarin derivatives bearing donor-acceptor substitutents or
rings are yellow dyes emitting a green fluorescence. In addition, the most widely used
commercial coumarin dyes are fluorescence dyes which contain an electron releasing group
such as N,N-diethylamino group in the 7-position of the coumarin ring, and in the 3-position,
a heterocyclic electron-acceptor residue [20,21]. To shift maximum absorption and emission
wavelength of coumarin dyes from UV region to near IR, some researchers synthesized
coumarin dyes containing cyano group, dicyanomethine, dicyanomethine vinyl moiety,
carbonylvinyl or heterocyclic ring such as benzoxazole, bezothiazole, benzimidazole as
electron acceptor in 3- or 4-position, rigid or free rotated alkylamino substituent at 7-position
of the main core [22-25]. Moreover, fluorescent bis-coumarin analogues were synthesized
having donor-acceptor-donor (D-A-D) system as red and NIR emitting dyes [26]. These types
of coumarin derivatives can be applied in many fields such as biolabeling, chemosensor,
NLO, etc. Furthermore, coumarins are also of considerable biological and medical interest
heterocyclic ring [27-38].
On the other hand, The anion/cation and biological important molecules such as enzymes,
proteins, amino acids etc. play a critical role in many metabolic processes. Therefore,
determination of anion/cation or biological important analytes with dyes have become a
highly hot topic of interest to Organic and Supramolecular chemists [39-61].
The determination of anions can be achieved by several methods including spectroscopic,
chromatographic, electrochemical and analytical techniques. However, for practical
applications need to simpler methods with minimal instrumental assistance. Colorimetric and
fluorimetric chemosensors can be alternative instead of the traditional methods for practical
3

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application in real sample. Therefore, the development of chromogenic chemosensors for
anions and cations recognition has become an attractive research field and synthesis of new
additional chemosensor is still required.
In view of the above mentioned findings, in this present work, we report synthesis,
photophysical, NLO, anion sensing ability, thermal stability, and biological activity of two
novel coumarin-indole conjugate donor-acceptor-donor (D-A-D) compounds (CI-1 and CI-
2
), in which a 7-diethylaminocoumarin donating group, dicyanomethylene moiety, as electron
acceptors, linked by an electron donor indole moiety, via vinylene (dimethine) bridge. The
photophysical properties and anion sensing abilities of the dyes were evaluated with DFT and
TD-DFT.
2
. Experimental
2
.1. Materials and instrumentation
All the chemicals used in the synthesis of the compounds were procured from the Aldrich
Chemical Company and used without further purification. The solvents used were of
spectroscopic grade. FT-IR (ATR) spectra were recorded on Perkin-Elmer Spectrum 100 FT-
-1
IR spectrophotometer (ν, are in cm ). NMR spectra were recorded on a Bruker Avance 300
Ultra-Shield in DMSO-d . Chemical shifts are expressed in δ units (ppm). Ultraviolet-visible
6
(UV-vis) absorption spectra were recorded on Shimadzu Corporation, Kyoto Japan UV-1800
2
40V spectrophotometer (Gazi University Department of Chemistry, Turkey) at the
wavelength of maximum absorption (λmax, in nm) in the range of the dielectric constant of the
solvents, i.e. Dimethylsulfoxide (DMSO, ε, 46.45), N,N-Dimethylformamide (DMF, ε,
3
6.71), Dichloromethane (CH Cl , ε, 8.93), Tetrahydrofurane (THF, ε, 7.58), Dioksan (ε,
2 2
4

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2
.21). Flourescence spectra were also recorded on a HITACHI F-7000 FL
Spectrofluorophotometer, in the same range of the same solvents. The slit width was 5 nm for
excitation and 5 nm emission. The PMT voltage was 700 V for each measurement. Mass
spectra were recorded on Waters-LCT-Premier-XE-LTOF (TOF-MS) instruments; in m/z (rel.
%) (Gazi University Laboratories, Department of Pharmacological Sciences). Chemical shifts
are expressed in δ units (ppm) with tetramethylsilane (TMS) as the internal reference.
Coupling constant (J) is given in hertz (Hz). Signals are abbreviated as follows: singlet, s;
doublet, d; triplet, t, and multiplet, m. Melting points were measured on Electrothermal
IA9200 apparatus and uncorrected. Thermal analyses were performed with a Shimadzu DTG-
−
1
−1
6
0H system, up to 600 °C (10 °C min ) under a dynamic nitrogen atmosphere (15 mL min ).
Typically, aliquots of a freshly prepared standard solution of the alkylammonium salt of the
−
−
−
−
−
−
−
−
4
anions (F , Cl , Br , I , AcO , CN , HSO and H PO ) were added, and their various UV-
4
2
1
vis spectra were recorded. H NMR titrations were carried out in DMSO-d solution.
6
2
2
3
.2. Synthesis and characterization
.2.1. Synthesis of (2)
.40 mmol of indole-3-carbaldehyde was dissolved in 5 mL of distilled DMF. Then, 3.4 mmol
of K CO and 1 mL CH I were added over it and stirred thoughly. The mixture was boiled
2
3
3
under nitrogen at 100 °C for 5 hours under reflux. The solution obtained after 5 hours was
o
cooled, precipitated with ice-water, and filtered. White solid, yield: 61% (0.33 g), m.p: 62 C,
1
H NMR (DMSO-d , 300 MHz): 9.9 (s, 1H), 8.29 (s,1H), 8.1 (d, 1H, J=7.24 ), 7.57(d, 1H,
6
J=8.014 ), 7.3 (dd, J=7.09, 1.15), 7.4 (dd, J=5.82, 4.61).
5

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2
.2.2. Synthesis of 3-acetyl-7-(diethylamino)-2H-chromen-2-one (3) and 2-1-(7-
(diethylamino-2-oxo-2H-chromen-3-yl)ethylidene)malononitrile (4)
Compounds 3 and 4 were synthesized by our previously reported procedures [62].
2
.2.2. General procedure for the preparation of (E)-2-(1-(7-(diethylamino)-2-oxo-2H-
chromen-3-yl)-3-(1H-indol-3-yl)allylidene)malononitrile (CI-1), and (E)-2-(1-(7-
diethylamino)-2-oxo-2H-chromen-3-yl)-3-(1-methyl-1H-indol-3-yl)allylidene)malononitrile
CI-2)
(
(
A mixture of 2-(1-(7-(diethylamino)-2-oxo-2H-chromen-3-yl)ethylidene)malononitrile (3) (10
mmol), piperidine (1 mmol), and indole-3-carbaldehyde, or 1-Methyl-1H-indole-3-
carbaldehyde (10 mmol), in ethanol (20 mL) was refluxed for 18 hours. After cooling to room
temperature, the precipitate was filtered and dried. The crude product was recrystallized from
ethylacetate to obtain the pure compound, in both cases, as fine red powder.
o
-l
(
CI-1): Yield 50% (0.22 g); mp: 282-283 C. FT-IR (ATR, υmax., cm ): 3256 (N-H) 2979,
2
1
1
7
7
1
925 (aliphatic C-H), 2212 (C≡N), 1705 (C=O), 1569 (aromatic C=C), 1331 (aromatic C-N),
1
236 aliphatic C-N); H NMR (DMSO-d , 300 MHz): 12.25 (brs, N-H), 8.14 (s, 1H), 8.08 (s,
6
H), 7.83 (dd, 1H, J = 6.36, 2.63 Hz), 7.68 (d, 1H, J = 15.17 ), 7.51 (m, 1H), 7.35 (d, 1H, J =
.05 Hz), 7.28 (m, 3H), 6.80 (dd, 1H, J = 8.74, 2.35), 6.64 (d, 1H, J = 2.19), 3.50 (q, 4H, J =
1
3
.15) 1.27 (t, 6H, J = 7.14) ppm; C NMR (DMSO-d , 75 MHz): 194.5, 185.6, 184.2, 179.0,
6
65.2, 151.8, 142.1, 141.5, 139.3, 134.5, 101.2, 71.5, 67.6, 67.30, 66.9, 66.3, 66.0; HRMS
(
ESI, CH CN) (C H N O ) found: 435.1831, calcd.: 435.1821.
3 27 22 4 2
o
-l
(
CI-2): Yield 60% (0.27 g); mp: 271-272 C, FT-IR (ATR, υ , cm ): 2971 (aliphatic C-H),
max.
2
210 (C≡N), 1705 (C=O), 1566 (aromatic C=C), 1329 (aromatic C-N), 1235 aliphatic C-N),
6

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1
H NMR (DMSO-d , 300 MHz): 8.14 (s, 1H), 8.08 (s, 1H), 7.83 (dd, 1H, J = 5.64, 2.20 Hz),
6
7
.68 (d, 1H, J = 15.19 ), 7.51 (m, 1H), 7.35 (d, 1H, J = 8.95 Hz), 7.28 (m, 3H), 6.80 (dd, 1H, J
8.98, 2.24), 6.64 (d, 1H, J = 2.16), 3.89 (s, 3H), 3.50 (q, 4H, J = 7.15) 1.27 (t, 6H, J = 7.14)
=
1
3
ppm; C NMR (DMSO-d , 75 MHz): 194.5, 185.6, 184.2, 179.0, 165.2, 151.8, 142.1, 141.5,
6
1
39.3, 134.5, 101.2, 71.5, 67.6, 67.30, 66.9, 66.3, 66.0; HRMS (ESI, CH CN) (C H N O )
3 27 22 4 2
found: 449.1962, calcd.: 449.1978.
Scheme 1 is here
3
. Results and discussion
3
.1. Synthetic strategy and structural characterization
The syntheses of CI-1 and CI-2 were performed by stepwise procedure demonstrated in
Scheme 1. The reaction of 2-(1-(7-(diethylamino)-2-oxo-2H-chromen-3-
yl)ethylidene)malononitrile (4) with indole-3-carbaldehyde (1) and 1-methylindole-3-
carbaldehyde (2) in the presence of piperidine gave E)-2-(1-(7-(diethylamino)-2-oxo-2H-
chromen-3-yl)-3-(1H-indol-3-yl)allylidene)malononitrile
(CI-1),
and
(E)-2-(1-(7-
(diethylamino)-2-oxo-2H-chromen-3-yl)-3-(1-methyl-1H-indol-3-yl)allylidene)malononitrile,
1
respectively. The structures of both compounds were confirmed by FT-IR, UV-vis, H NMR,
1
3
C NMR and HRMS techniques. The spectral data were consistent with the proposed
structures (Supplementary material Figs. S1-9).
The FT-IR spectra of the prepared dye CI-1 showed two characteristic bands at 3256 and
-1
1
705 cm , corresponding to amine (N-H, belong to indole moiety) and carbonyl (C=O,
belong to coumarin moiety), respectively. Dye CI-2 showed carbonyl (C=O) band at 1705
7

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-1
cm . Donor-π-acceptor compounds bearing vinyl bridge can show cis-trans (E/Z) isomer in
solution. The determination of more stable isomer is quite important for evaluating their
1
photophysical properties. H NMR spectroscopy is useful in the measurement of the
configuration of the vinylic double bond. The configuration of the E-isomer could be noticed
by NMR spectroscopic analysis. The assignment of the E-configuration of the vinylic double-
bond was based on the analysis of the vicinal coupling constants of the olefinic protons,
because the latter exhibit the characteristic coupling constant of J~15-16 Hz. This coupling
constant for the vinylic protons of CI-1 and CI-2 clearly supports the selective formation of
1
E-configuration of the vinylic double-bond. In addition, in the H NMR spectra of CI-1, the
NH peak was observed at 12.25 ppm in DMSO-d6.
3
.2. Photophysical properties
Recently, many push-pull chromophores have also been used extensively as fluorescent
emitters because of their good absorption and fluorescence properties. For examples,
Dicyanomethylene-4H-pyran (DCM) in particular, is a very well-known red emitter for
OLED application [63]. Therefore, in this study DCM-like new chromogenic dyes (CI-1 and
CI-2) bearing well-known fluorescent core coumarin, were designed and synthesized as D-π-
A type push-pull system. The synthesized dyes consist of 7-diethylaminocoumarin and indole
moiety as a donor part and dicyanomethylene at the 3-position of coumarin moiety as an
acceptor part in the structure. Generally, the polarity of solvents strongly affects the excited
state of the donor-acceptor compounds via stabilize dipole-dipole, hydrogen bonding, and
solvation interactions. Therefore, in the present study, the solvent dependent absorption as
well as emission behavior of these compounds were evaluated in solvents of various dielectric
constants. The effect of solvent polarity on absorption and photoluminescence (PL) properties
8

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of the dyes was studied in five aprotic solvents (DMSO, DMF, CH Cl , THF and Dioxan in
2
2
-5
3
x10 M) of various polarity. The UV-vis and photoluminescence (PL) spectroscopic data of
compounds CI-1 and CI-2 measured in studied solvents at room temperature are presented in
Table 1. Effects of solvent polarity on absorption and emission spectra of the dyes, and the
color changes observed in day light, upon UV irradiation (365 nm) of compounds in diverse
solvents, are shown in Fig.1. and Fig.2.
Dyes CI-1 and CI-2 displayed solvatochromic properties in all the solvents. They also
showed red shifted absorption with increase in solvent polarity that is for CH Cl (λ is 446
2
2
abs
nm and 461 nm, for CI-1 and CI-2, respectively), for DMSO (λabs is 470 nm and 477 nm, for
CI-1 and CI-2, respectively) (Fig. 1, Table 1). One dominant absorption band at a long
wavelength with a shoulder at short wavelength was observed in all solvents used for both
dyes. Any of the dyes which has one absorption band with shoulder, may exhibit E-Z
isomerization. In addition, CI-1 showed one additional absorption maximum at long
wavelengt in DMF. This maximum absorption wavelength can be attributed to anionic form
of the dye.
In push-pull dipolar molecules have been seen photoinduced charge transfer with
characteristic absorption band. In this study, it was found that the maximum absorption
shifted from 446 nm to 461 nm when CH is attached to the indole ring as electron-donating
3
substituent, in CH Cl . This result is in agreement with the assumption of intramolecular
2
2
charge transfer (ICT), and an ICT enhancement results in the bathochromic shift of the
absorption bands. The same behaviour was observed for the rest of the solvents used.
The emission spectra were obtained using 5 nm slit width, and 10 mM stock solute
concentration, by exciting the samples at its wavelength of emission maxima and the results
obtained are summarized in Table 1. There was no regular correlation between the change of
solvent polarity and emission maxima. It was observed that the change in solvent polarity did
9

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not have significant influence on emission curve (Fig.1, Table 1). However, the fluorescence
intensity of the compounds decreased with the increasing polarity of the solvents, which is
different from the common results in the emission intensity of ICT compounds such as styryl
dyes [64]. It may be due to the stabilization of the excited state in polar solvent environment
leading to quenching of fluorescence intensity which suggests that there is positive
solvatochromism with negative solvatofluorism [65]. The largest Stokes shifts were observed
in CH Cl (151 nm) for the chromophores.
2
2
Table 1 is here
Figures 1a and 1b are here
3
.2. UV-vis absorption titration of CI-1 and CI-2 with various anions
The anion binding and the sensing ability of the novel push-pull dyes CI-1 and CI-2 were
performed in DMSO using spectrophotometric and spectrofluorimetric titration techniques.
Aprotic, polar and water miscible DMSO was chosen as the solvent for anion titrations to
avoid anion-solvent interactions. The anion titrations were performed with different molar
equiv of TBA salts of anions. Fig.3 shows the changes in the absorption spectrum of CI-1
-5
−
−
−
(
2×10 M) in DMSO in the absence and the presence of F , AcO and CN anions at room
temperature. The main band of CI-1 dye observed at 466 nm decreased gradually, and upon
−
adding F anion, an increased and a new absorption maximum was observed at 530 nm. The
color change of the dye was also observed by the naked eye, simultaneously, from yellow to
−
red in the presence of F (see Fig. 4). An isosbestic point was observed at 497 nm during the
titration process, indicating that a stable binding complex was formed between receptor CI-1
−
and fluoride anion. As shown in Fig.3, titration profile of CI-1 with F found to be 40 equiv
1
0

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−
of F reacting with CI-1 could reach equilibrium. Which indicated that the dye interact with
−
F by hydrogen bonding at solution phase and deprotonated during addition of fluoride ion.
This result shows that a ground-state equilibrium between neutral CI-1 and deprotonated CI-
+
H has been formed, which can be attributed to an indole moiety (Scheme 2). In this form, the
negative charge on the indole nitrogen is completely delocalized, leading to the
experimentally observed bathochromic shift at 530 nm, as compared to the neutral form. The
−
optical response on interaction with F can be explained by the fact that ICT process occurred
between the indole nitrogen and the electron-withdrawing dicyanomethylene with the
−
formation of a hydrogen bonded complex between the F of chemosensor and the anion
−
−
added. The same spectral response towards AcO and CN anions was observed as shown in
Fig. 3.
Figure 4 is here
We investigated the reversibility of the anions sensing upon addition of trifluoroacetic acid
+
(
TFA) in fluoride titrated CI-1 solution. The absorption spectral change of CI-1-H with the
addition of TFA in DMSO solution is shown in Fig. 5 and Scheme 2. Addition of 40 equiv of
+
TFA to t solution of CI-1-H , resulted in the disappearance of the absorption bands at 533
nm. Again, a new absorption maximum was observed at a shorter wavelength with the same
absorption maximum at 466 nm of the neutral form, upon addition of 40 equiv of TFA.
Figure 5 is here
Scheme 2 is here
1
1

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−
−
The addition of F and CN resulted in a yellow-to-pink colour change, whereas a yellow-to-
−
orange colour change was observed in the case of AcO (Fig.4). No considerable color
−
−
−
−
−
4
changes were seen when Cl , Br , I , HSO and H PO ions were added, which was
4
2
consistent with the results observed from spectral titrations (Supplementary material Figs.
S10-12).
We carried out the sensing test of CI-1 to test for anions in the water. Because the anion
affinity may be changed if the same experiment is carried out in aqueous medium due to the
hydration of the anions by water. The detection of anions in real samples was also simulated
by using DMSO/H O binary solution. Indeed, when chemosensor CI-1 was treated with the
2
−
−
−
some selected anions; F , AcO and CN (25 equiv of each) in DMSO/H O (9:1) binary
2
−
solution, there was a distinctive absorption maximum change with CN only (Fig.6). Upon
−
addition of CN to the receptor, the absorption maximum of CI-1 shifted bathochromically.
−
This phenomenon was observed upon addition of CN only. However, the new color 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 CI-1 displayed a color change from
−
yellow to red. However, no significant color change was observed upon addition of F and
−
AcO (Fig.7).
Figures 6 and 7 are here
CI-2 has no acidic hydrogen and is composed of a 7-diethylaminocoumarin fluorophore, and
a dicyanomethylene moiety, as strong electron acceptor linked to the indole moiety via
dimethine, and for activating the Michael acceptor for cyanide anion. Such a molecular design
makes probe CI-2 possess the expanded π-conjugation as well as the strong ICT from the
indole to the conjugated dicyanomethylene moiety, which will lead to the red absorption
1
2

ACCEPTED MANUSCRIPT
−
maximum. Upon addition of CN , the absorbance at 476 nm gradually decreased with a new
peak appearing at 391 nm. 20 equiv of cyanide was sufficient to drive the reaction to
completion. It is expected that cyanide anion can add to the δ-position of an activated Michael
−
acceptor to generate the stabilized anionic species CI-2-CN . Apparently, after addition of
−
CN , it leads to the collapse of the donor–acceptor system, and a hypsochromic shift of
absorption maxima was observed (Fig.8). As a result, the π-conjugation between
indole/coumarin and dicyanomethylene was blocked and then obvious spectra and color
changes were observed. The same hypsochromic shifts were also observed for coumarin
−
based donor-acceptor dyes [66,67]. In addition, upon addition of CN to a solution of CI-2, an
obvious color change from orange to yellow was clearly observed (Fig.9). No considerable
−
−
color changes were seen when F and AcO ions were ratiometrically added to the solution of
CI-2. As a result, a ratiometric colorimetric response, as well as an obvious color change
could be expected. Therefore, CI-2 can serve as cyanide sensor.
Figures 8 and 9 are here
1
3
.3. H NMR titrations study
The results from spectrophotometric titration clearly showed that probe CI-1 associates with
−
−
AcO and F via a hydrogen bonding interaction between the indolic acidic NH proton of CI
−
−
−
and AcO and F . The interaction between the probe with CN showed that there is a diffirent
mechanism beside deprotanation. To gain an insight into the nature of the ground interaction
−
1
between CI-1 and F , we recorded the H NMR spectra of the probe in DMSO solution
without, and with added TBAF in DMSO-d . As shown in Fig. 10, addition of just 1 equiv of
6
TBAF resulted in the complete disappearance of the NH signal of the probe at 12.25 ppm,
1
3

ACCEPTED MANUSCRIPT
−
while a new broad signal, attributable to the formation of HF complex, was observed at δ
2
−
−
1
6.0 ppm after addition of 8 equiv F because of proton transfer from N-H to F . After
deprotonation of indol NH, electron density on indol moiety and ICT from indol donor to
dicyanomethylene acceptor increase and thus some protons can shift upfield. The shielding
effect of the negatively charged indole ring is an evident of the upfield shifts of the aromatic
−
proton at the 2-position of the indol ring (Hb) upon the addition of 8 equiv of F to the
solution of CI-1. In addition, the negative charge shift also promotes upfield shift of the
vinylic CH protons (i.e. Hc and Hd) which shifted slightly upfield, upon addition of same
−
amount of F to the solution of CI-1.
−
−
The AcO ion is basically a competing anion with F ion. However, the same behavior was
−
observed in AcO ion when it was interacted with the probe in DMSO solution. With the
−
addition of 9 equiv of AcO to the solution of CI-1, deprotonation probably occurred, which
led to an increase in the electron density on the indole heterocyclic ring (Supplementary
material Fig. S13).
Figure 10 is here
−
−
−
CN is different from F and AcO when the receptor affinity is taken into account. Therefore,
we evaluated its interaction mechanism with the compounds, and CI-2 has been choosen as
the model compound instead of CI-1. This is because CI-2 has no any acidic hydrogen and
−
only nucleophilic addition with CN will be observed. To further understand the mechanisms
−
−
−
between CN and CI-1, and also CN and CI-2, both compounds were titrated with CN . Upon
−
addition of 6 equiv of CN to the solution of CI-1, Ha and Hb signals which were at 8.14 and
1
2.25 ppm respectively, disappeared. While Ha signal disappearance indicates the
deprotanation of NH proton, Hb signals suggest cyanide addition to carbon at 2-position of
1
4

ACCEPTED MANUSCRIPT
the indole ring. For confirmation of this mechanism we did the same with CI-2 which doesn’t
−
have acidic NH proton for deprotonation. Within the addition of 2 equiv of CN to the
solution of CI-2, Hb proton as was expected disappeared, and the He at 3-position of
coumarin ring at 8.08 ppm, also disappeared. However, for Hg and Hh at 6 and 8-position
respectively, of the coumarin ring, their signals were shifted upfield. This results indicates
that, beside the addition of cynide to 2-position of the indol ring, there is also an addition to 4-
position of cumarin ring.
All the observed differences on the proton signals of CI-1-CN adduct suggest that, two
1
different mechanisms (deprotonation and addition) occur at the same time in H NMR
titration for CI-1, but at the end of the titration, the major product was produced by the
1
−
deprotonation reaction (Fig. 11). In addition, H NMR of CI-2-CN adduct showed that, CN
was added at the 4-position of the coumarin, and 2-position of the indol ring, via nucleophilic
addition reaction (Fig. 12).
Figures 11 and 12 are here
The ground state geometry of the synthesized dyes was optimized within a framework of
Gaussian 09 [68] using the density functional theory (DFT) method. The calculations were
performed using the Becke’s three-parameter exchange function with the Lee–Yang–Parr
correlation function (B3LYP) [69-71] applying the 6-31+G(d,p) basis set without any
symmetry restrictions in the gas phase. The harmonic vibrational frequency calculations using
the same methods, as that of the geometry optimizations, were used to ascertain the presence
of a local minimum. The vertical excitation energies and oscillator strengths were obtained
for the lowest 10 singlet-singlet transitions at the optimized ground state equilibrium
geometries, by using TD-DFT at the same hybrid functional and basis, set in CH Cl , dioxan,
2
2
DMF, DMSO, THF solutions using the polarizable continuum model (PCM) [72]. Besides,
1
5

ACCEPTED MANUSCRIPT
−
−
detailed information about absorption changes, upon the reactions of F and AcO with CI-1,
were obtained using DFT and TD-DFT calculations and were parallel to the experimental
results. In addition, nonlinear optical properties, the electric dipole moment (µ), polarizability
(α), anisotropy of polarizability (ꢀα) and molecular first hyperpolarizability (β) of the
molecules were evaluated in the gas phase.
3
.4.1. Electronic properties
The calculated vertical excitation energies and oscillator strengths obtained for the lowest
energy transition with transitions with highest orbital contributions for CI-1 and CI-2 (Fig.
1
3) are presented in Table 2. As seen in the Table, the calculated values are in good
agreement with the experimental ones. In all solvents, the absorption bands of both CI-1 and
CI-2 molecules consist of two peaks (λmax= 439, 378 nm in CH Cl , λmax= 434, 368 nm in
2
2
dioxan, λmax= 441, 380 nm in DMF, λmax= 441, 380 nm in DMSO, λmax= 438, 377 nm in THF
for CI-1, λmax= 447, 377 nm in CH Cl , λmax= 431, 368 nm in dioxan, λmax= 449, 380 nm in
2
2
DMF, λmax= 448, 380 nm in DMSO, λmax= 446, 376 nm in THF for CI-2). When we
compared the calculated values with the experiment ones, it was seen that the largest
difference in λmax, between each of the two peaks, was 29 nm in DMSO for both CI-1 and CI-
2
. On the other hand, the absorption maxima of CI-2 is slighly red shifted as compared to that
of CI-1 because of the addition of electron-donating group (CH ) at the 1-position of indole.
3
In addition, the TD-DFT calculations showed that, the main transition at high wavelength
correponds to HOMO-1→LUMO transition, and the other at low wavelength corresponds to
HOMO→LUMO+1 for CI-1 and CI-2.
Figure 13 and Table 2 are here
1
6

ACCEPTED MANUSCRIPT
3
.4.2. Sensing mechanism of CI-1
In parallel to experimental study, to get further understanding on the interaction of CI-1 with
−
−
-
-
F and AcO anions, we optimized the structure of CI-1 complexes with F and AcO in gas
-
phase as shown in Fig. 13. The optimized structures of CI-1 and its complexes with F and
−
−
−
AcO anions (CI-1+F , CI-1+AcO ) in gas phase are shown in Fig. 13. It was observed that,
the amide NH bond lenght of CI-1 increased from 1.008 Å to 1.507 Å, and then to 1.136 Å
−
−
upon its interaction with F and AcO anions, respectively, through hydrogen bonding, which
was followed by deprotonation process. The comparison of the Mulliken’s atomic charges on
nitrogen atom of indole for the optimized structures showed the change from −0.275 to
-
−
−
0.354, and−0.285 after the formation of CI-1+F and CI-1+AcO complexes, respectively.
The increased negative charge caused an enhanced ICT within the molecule and decreasing
the energy gap between HOMO and LUMO (HOMO for the highest occupied molecular
orbitals, LUMO for the lowest unoccupied molecular orbitals) resulting in red shift, which is
in accordance with the observed absorbance spectra.
−
−
To get detailed information about the absoption spectra of CI-1, CI-1+F , and CI-1+AcO ,
the TD-DFT (time-dependent density functional theory) calculations were carried out at
B3LYP/6-31+G(d,p) level in DMSO at the optimized geometries. For CI-1, the TD-DFT
calculations showed main transition at 441 nm with an oscillator strength of f = 0.7430 which
corresponds to HOMO-1→LUMO transition, and the other at 380 nm with f = 0.5863 which
corresponds to HOMO-1→LUMO+1 (6.6%) and HOMO→LUMO+1 (89.7%) transitions.
−
When CI-1 formed a complex with F , the absorption peak appeared at 518 nm, red-shifted
by 77 nm, which is in good agreement with the experimental absorption change of 67 nm. The
−
−
AcO interaction with CI-1 resulted in similar behavior as seen in CI-1+F and the peak
appeared at 520 nm, red-shifted by 79 nm compared with CI-1. These observed absorption
1
7

ACCEPTED MANUSCRIPT
−
−
maxima of CI-1+F and CI-1+AcO were found to correspond to HOMO→LUMO
−
−
(
contribution is 92.5% for CI-1+F , 71.6% for CI-1+AcO ) and HOMO-1→LUMO (5.6%
−
−
for CI-1+F , 27.8% for CI-1+AcO ). The molecular orbitals that are relevant to the
−
−
excitations for CI-1 and CI-1+F and CI-1+AcO are given in Fig. 14. It is seen that HOMO
−
−
and LUMO orbitals of CI-1+F and CI-1+AcO are mainly delocalized on the donor indole
moiety and acceptor dicyanomethylene through π-bond conjugation. After excitation from
HOMO to LUMO, ICT occurs from indole moiety on the donor to the acceptor end, resulting
in the fluorescence quenching. The results obtained from calculations were in good agreement
with the experimental results.
Figure 14 is here
3
.4.3. Molecular Electrostatic Maps (MEP)
MEP is highly useful in predicting the reactive behavior of molecules. To predict reactive
sites for the electrophilic and nucleophilic process for CI-1 and CI-2, MEP surface was
obtained at the B3LYP/6-31+G(d,p) optimized geometry shown in Fig.15. The negative (red
and yellow) regions of MEP were related to electrophilic reactivity and the positive (blue)
ones to nucleophilic reactivity. As seen in MEP map of CI-1 in Fig.15, N-H bond indicates a
possible site for attack of anions. It gives an information about the region where the molecule
can have intermolecular interactions.
1
8

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3
.4.4. Nonlinear Optical Properties (NLO)
Nonlinear optics (NLO) deals with the interactions of applied electromagnetic fields in
various materials to generate new electromagnetic fields, altered in frequency, phase and
other physical properties [73]. It is known that the investigations of NLO materials have been
the subject of intense research because of their possible applications in a wide range of
technologies, such as optical communication, optical computing and data storage [72-75].
In this study, the electric dipole moment (µ), polarizability (α ) and molecular first
tot
hyperpolarizability (β ) of CI-1 and CI-2 were calculated at B3LYP/6-31+G(d,p) level in gas
tot
phase. The obtained results are given in Table 3. As seen in Table 3, the values of α and
tot
-24
-30
-24
-30
βtot were obtained as 65.6 x10 esu and 57x10 esu for CI-1, 68.2x10 esu and 59.2x10
esu for CI-2. As expected, α and β for CI-2 are larger than those for CI-1 because of the
tot
tot
addition of electron-donating group (CH ) at the 1-position of the indole. On the other hand,
3
the values of α and β for CI-1 and CI-2 were found to be greater than those of urea (α
tot
tot
tot
-24
‒30
and βtot of urea are 4.9x10 esu and 0.49×10
esu obtained by B3LYP/6-31+G(d,p)
method) which is one of the prototypical molecules used in the study of the NLO properties of
molecular systems. The results show that the value of the first hyperpolarizability (β ) are
tot
more than ~120 times larger than the magnitude of urea. According to the magnitute of the
first hyperpolarizability, the studied compounds may be potential applicants in the
development of NLO materials.
3
.5. Thermal analysis
The thermal stability of the dyes CI-1 and CI-2 has a fundamental characteristic deciding
their suitability for applications as functional dyes in many fields such as chemosensors and
1
9

ACCEPTED MANUSCRIPT
as optic dyes. Dyes CI-1 and CI-2 were used to carry out thermal gravimetric techniques
(TGA). The thermo gravimetric studies were conducted at 30-600 °C under nitrogen gas at a
-1
heating rate of 10 °C min . The TGA result indicated that CI-1 has two thermal
decomposition temperatures (T ) 160 °C and 299 °C. CI-1 is stable up to 160 °C, and lost
d
8
8% weight at that temperature, as shown in Fig. 16. TGA revealed the onset decomposition
temperature (T ) at 299 °C for CI-1 whose thermogravimetric curve showed a major loss in
d
weight. However, CI-2 was found to be more stable than CI-1, and there was no
decomposition band till at 325 °C. As a results, the dyes showed good thermal stabilities
approximately up to 300 °C, which is high enough for industrial applications when use as
chemosensors or optic dyes.
Figure 16 is here
3
.6. In vitro antimicrobial activity
The antimicrobial activity of the compounds (CI-1 and CI-2) were tested against both types
of Gram-positive (Bacillus cereus NRRL B-3711, Bacillus subtilis ATCC 6633,
Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212) and Gram-
negative bacteria (Escherichia coli ATCC 35218, Escherichia coli ATCC 25922,
Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumaniae ATCC 13883, Salmonella
typhimurium ATCC 14028) and fungi (Candida albicans ATCC 10231, Candida krusei
ATCC 6258, Candida tropicalis Y-12968). Microorganism strains used were obtained from
the collections of Gazi University Molecular Biology Culture Collection, Turkey. For
comparison, ampicillin (10 µg), chloramphenicol (30 µg), (antibacterial) and ketoconazole
(50 ꢁg), (antifungal) were used as the standard antimicrobial agents. Test strains were
2
0

ACCEPTED MANUSCRIPT
incubated on nutrient agar plates at 37 °C for 24 h for bacteria. The yeast cells were cultured
on Sabouraud dextrose agar medium and incubated at 30 °C for 48 h. After incubation,
bacterial suspensions were adjusted to a turbidity of 0.5 McFarland. Mueller Hinton agar (for
bacterial strains) and sabouraud dextrose agar (for fungal strains) mixed with 1% culture
suspension and poured into the plates. Wells were prepared with a 6.0 mm diameter and the
solution (50 µL) of the 5000 µM test compound was poured into the well. The diameter of the
inhibition zone was measured in millimeters.
The antimicrobial activity of the compounds CI-1 and CI-2 were evaluated against nine
bacterial and three fungal test strains (Table 4). Compound CI-1 had silightly inhibitory
effect on E. coli, P. aeruginosa, K. pneumaniae, S. typhimurium bacterial species, and
moderate effect on C. albicans yeast species. On the other hand, compound CI-2, had quite
strong antifungal activity against pathogenic candida species of C. krusei, C. albicans and C.
tropicalis. Minimal Inhibitory Concentrations and Minimal Fungicidal Concentrations are
the lowest concentration of a chemical that prevents visible growth of a microorganism and is
the lowest concentration of an antifungal agent to kill particular fungi, respectively. The MIC
and MFC values of the compounds are given in Table 5. MIC values ranged from 10-80 µM,
whereas MFC ranged from 20-80 µM.
Tables 4 and 5 are here
2
1

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3
.7. The DNA interaction with the compounds (CI-1 and CI-2)
The interaction of the synthesized compounds with plasmid DNA was studied by agarose gel
electrophoresis. Stock solutions of the compounds in DMSO were prepared and used
immediately. The aliquots of decreasing concentrations of the compounds, ranging from 150
to 3.125 µM, were incubated with plasmid DNA in the dark at 37 °C for 24 h. The loading
buffer (0.1 % bromophenol blue, 0.1 % sucrose) was added to the mixtures and loaded onto
the 1% agarose gel. Electrophoresis was carried out under TAE buffer (0.05 M Tris base, 0.05
M glacial acetic acid and 1 mM EDTA, pH=8.0) for 3 h at 70 V. The gel was stained with
ethidium bromide (0.5 µg/mL), visualized under UV light using a transilluminator (BioDoc
Analyzer, Biometra) and the image was captured with a video camera as a TIFF file. The
experiments were repeated three times, and the mean values were presented.
The plasmid DNA was treated with compounds CI-1 and CI-2 in the dark at 37 °C for 24 h,
and then the mobilities of the DNA forms were studied in an agarose gel electrophoresis. Fig.
1
7 shows the electrophoretograms applied to the incubated mixtures of DNA at various
concentrations (150 µM-3.125 µM) of the compounds. Lane P applies to the untreated
plasmid DNA (control DNA), showing the major supercoiled circular (form I) and minor
singly nicked relaxed circular (form II) forms of the plasmid DNA. Lanes 1-7 apply to
plasmid DNA incubated with compounds ranging from 150 µM to 3.125 µM.
When the plasmid DNA was incubated with decreasing concentrations of the compounds CI-
1
and CI-2, the mobility of form I DNA decreased at three high concentrations, and then
increased slightly, In case of form II, the intensity decreased at the first high concentration,
then increased slightly with the decreasing oncentration of the compounds.
Figure 17 is here
2
2

ACCEPTED MANUSCRIPT
3
.8. Determination of nucleotides interacted with the nucleotides
The compounds/plasmid DNA mixtures were incubated for 24 h, and then restricted with
BamHI or HindIII enzyme at 37 °C in order to determine the nucleotides to which the
compound binds. The restricted DNA was run in 1% agarose gel electrophoresis in TAE
buffer. The gel was stained with ethidium bromide (0.5 µg/mL), and the gel was then viewed
with a transilluminator, while the image was photographed with a video-camera and saved as
a TIFF file. Fig. 18 illustrates the electrophoretogram for the BamHI and HindIII digested
mixtures of plasmid DNA after their treatment with the compounds. Untreated plasmid DNA
was applied to lane 1. Lane 2 applies to plasmid DNA digested with BamHI. Lanes 3-5 apply
to plasmid DNA interacted with the compound BT1, and lanes 6-8 apply to plasmid DNA
interacted with the compound BT1 followed by their digestions with BamHI and HindIII. In
case of digestions of the compounds CI-1 and CI-2 with BamHI and HindIII, Form I, Form II,
and Form III were observed, showing that the compounds bind to A/A and G/G nucleotides.
Figure 18 is here
4
. Conclusions
In conclusion, a novel coumarin-indole conjugate push–pull chromophores (CI-1 and CI-2)
1
13
have been synthesized by Knoevenagel condensation, and characterization by IR, H/ C
1
NMR and HRMS. Both dyes are stable E isomers that is confirmed by H NMR spectra. The
effect of solvent polarity on absorption and emission maxima of the dyes was studied in five
aprotic solvents of various polarities was investigated. The dyes displayed solvatochromic
properties in all the solvents used.
2
3

ACCEPTED MANUSCRIPT
−
−
CI-1 behaved as a colorimetric probe for selective and sensitive detection of F , AcO and
−
CN in a biologically competing solvent like DMSO. However, it showed selective
−
−
−
determination of CN in DMSO/H O (9:1) over other competing anions such as F and AcO .
2
−
This result indicated that CI-1 could be used as a highly selective colorimetric sensor for CN
in DMSO/H O (9:1). In addition, when CI-2 was treated with some selected anions, such as
2
−
−
−
−
F , AcO and CN , only CN reacted with chromophore CI-2 via Michael addition, and the
main absorption maxima shifted hypsochromically, and a distinctive color change was
observed from orange to yellow. The TGA result shows that the dyes have an enough thermal
stability for applications. Also, this study showed that CI-2 has potential uses, and can act
against the tested fungal strains. In addition, both compounds CI-1 and CI-2 exhibited
conformational alterations in DNA. It is generally accepted that, DNA is an important and
major pharmacological target for drug design. Since DNA is able to adopt a variety of
different conformations according to the environmental factors, as well as naturally occurring
in different forms, DNA as the plasmid is potentially used to test for antitumor drugs. For
example, cisplatin is a well-known antitumor drug and its main target is DNA. It is
responsible for the cure of over 90% of testicular cancer [76]. DNA-compound interactions
studies are based on mobility and conformations changes of plasmid DNA. Hence, we tried to
find out DNA binding mode and the types of nucleotides binding. We concluded that, both
compounds CI-1 and CI-2 can cause conformational changes on DNA and can selectively
bind to nucleotides of A/A and G/G.
Acknowledgements
This work was supported by Gazi University.
2
4

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Supplementary material
1
13
Supplementary data (Copies of H NMR, C NMR, HRMS and absorption spectra on anions-
chemosensor interactions Figs. S1–S13) associated with this article can be found, in the
online version, at…..
References
[
1] R.M. Christie, C. Lui, Studies of fluorescent dyes: part 1. An investigation of the
electronic spectral properties of substituted coumarins, Dye Pigm. 42 (1999) 85-93,
doi:http://dx.doi.org/10.1016/S0143-7208(99)00012-1.
[
[
2] R. O'-Kennedy, R. Douglas Thornes (Eds.), Coumarins: Biology, Applications and
Mode of Action, New York: John Wiley, 1997.
3] X. Liu, J.M. Cole, P.G. Waddell, T.C. Lin, J. Radia, A. Zeidler, Molecular origins of
optoelectronic properties in coumarin dyes: toward designer solar cell and laser
applications, J. Phys. Chem. A 116 (2012) 727–737, doi:http://dx.doi.org/
10.1021/jp209925y.
[
[
4] F.A. Mir, Optical and Schottky diode performance of Au/4-hydroxy Coumarin/ ITO
heterojunction, Opt. Int. J. Light Electron Opt. 126 (2015) 24–27, doi:http://
dx.doi.org/10.1016/j.ijleo.2014.07.146.
5] S. Kumar, P. Singh, R. Srivastava, R.R. Koner, A. Pramanik, J. Mathew, S. Sinha, M.
Rawat, R.S. Anand, S. Ghosh, Engineering fused coumarin dyes: a molecular level
understanding of aggregation quenching and tuning electroluminescence via alkyl chain
substitution,
J.
Mater.
Chem.
C
2
(2014)
6637–6647,
doi:http://dx.doi.org/10.1039/C4TC00807C.
2
5

ACCEPTED MANUSCRIPT
[
6] S.S. Keskin, N. Aslan, F. Bayrakçeken, Optical properties and chemical behavior of
laser-dye Coumarin-500 and the influence of atmospheric corona discharges,
Spectrochim. Acta
A
Mol. Biomol. Spectrosc. 72 (2009) 254–259,
doi:http://dx.doi.org/10.1016/j.saa.2008.09.024.
[
[
7] G. Signore, R. Nifosì, L. Albertazzi, B. Storti, R. Bizzarri, Polarity-sensitive coumarins
tailored to live cell imaging, J. Am. Chem. Soc. 132 (2010) 1276–1288,
doi:http://dx.doi.org/10.1021/ja9050444.
8] L. Huang, Y. Chen, B. Liang, B. Xing, G. Wen, S. Wang, X. Yue, C. Zhu, J. Du, X.
Bu, A furanyl acryl conjugated coumarin as an efficient inhibitor and a highly selective
off-on fluorescent probe for covalent labelling of thioredoxin reductase, Chem.
Commun. 50 (2014) 6987–6990, doi:http://dx.doi.org/10.1039/c4cc02119c.
9] M. Peng, Y. Guo, X. Yang, L. Wang, J. An, A highly selective ratiometric and
colorimetric chemosensor for cyanide detection, Dye Pigm. 98 (2013) 327–332,
doi:http://dx.doi.org/10.1016/j.dyepig.2013.03.024.
[
[
10] X. Zhou, X. Lv, J. Hao, D. Liu, W. Guo, Coumarin-indanedione conjugate as a doubly
activated Michael addition type probe for the colorimetric and ratiometric fluorescent
detection
of
cyanide,
Dye
Pigm.
95
(2012)
168–173,
doi:http://dx.doi.org/10.1016/j.dyepig.2012.03.025.
[
[
11] F. Ge, H. Ye, H. Zhang, B. Zhao, A novel ratiometric probe based on rhodamine B and
coumarin for selective recognition of Fe(Ⅲ) in aqueous solution, Dye Pigm. 99 (2013)
661–665, doi:http://dx.doi.org/10.1016/j.dyepig.2013.06.024.
12] B. Babür, N. Seferoğlu, M. Öcal, G. Sonugur, H. Akbulut, Z. Seferoğlu, A novel
fluorescence turn-on coumarin-pyrazolone based monomethine probe for biothiol
detection,
Tetrahedron
(2016)
4498–4502,
doi:http://dx.doi.org/10.1016/j.tet.2016.06.008.
2
6

ACCEPTED MANUSCRIPT
[
13] H. Wang, L.E. Guo, X.M. Li, L. M. Zhang, Q.L. Xu, G. F. Wu, Y. Zhou, J.F. Zhang,
Coumarin-based turn-on fluorescence probes for highly selective detection of Pi in cell
culture and Caenorhabditis elegans, Dye Pigm. 120 (2015) 293–298,
doi:http://dx.doi.org/10.1016/j.dyepig.2015.04.031.
[
[
14] X.M. Peng, K.V. Kumar, G.L.V. Damu, C.H. Zhou, Coumarin-derived azolyl ethanols:
synthesis, antimicrobial evaluation and preliminary action mechanism, Sci. China
Chem. 59 (2016) 878–894, doi:http://dx.doi.org/ 0.1007/s11426-015-0351-0.
15] S. Erbas-Cakmak, F.Pir Cakmak, S. Demirel Topel. T.B. Uyar, E.U. Akkaya, Selective
photosensitization through and logic response: optimization of the ph and glutathione
response of activatable photosensitizers, Chem. Commun. 51 (2015) 12258–12261,
doi:http://dx.doi.org/10.1039/C5CC01261A.
[
16] I. Simsek Turan, F. Pir-Cakmak, D. Cansen Yildirim, R. Cetin-Atalay, E. U. Akkaya,
Near-ir absorbing bodipy derivatives as glutathione-activated photosensitizers for
selective photodynamic action, Chem. Eur. J. 20 (2014) 16088–16092,
doi:http://dx.doi.org/10.1002/chem.201405450.
[
[
[
17] S. Demirel Topel, G. Turgut Cin, E. U. Akkaya, Near ir excitation of heavy atom free
bodipy photosensitizers through the intermediacy of upconverting nanoparticles
Chem. Commun. 50 (2014) 8896–8899, doi:http://dx.doi.org/10.1039/C4CC03387F.
18] E, Ertem, A. Bekdemir, A. Atilgan, E. U. Akkaya, Near-ir absorbing bodipy
functionalized spions: a potential magnetic nanoplatform for diagnosis and therapy,
Pure Appl. Chem. 86 (2014) 899–903, doi:http://dx.doi.org/ 10.1515/pac-2013–1114.
19] M. Isik; R. Guliyev, S. Kolemen, Y.Altay, B. Senturk, T. Tekinay, E. U. Akkaya,
Designing an intracellular fluorescent probe for glutathione: two modulation sites for
selective signal transduction, Org. Lett. 16 (2014) 3260–3263, doi:http://dx.doi.org/
10.1021/ol501272z.
2
7

ACCEPTED MANUSCRIPT
[
[
[
[
[
20] S. Zhou, J. Jia, J. Gao, L. Han, Y. Li, W. Sheng, The one-pot synthesis and fluorimetric
study of 3-(20-benzothiazolyl)coumarins, Dye Pigm. 86 (2010) 123–128,
doi:http://dx.doi.org/ 10.1016/j.dyepig.2009.12.005.
21] K.K. Sanap, S.D. Samant, Synthesis of coumarin based fluorescent compounds,
Tetrahedron
Lett.
53
(2012)
5407–5410,
doi:http://dx.doi.org/10.1016/j.tetlet.2012.07.111.
22] A.B. Tathe, N. Sekar, Red-emitting NLO phoric carbazole-coumarin hybrids- Synthesis,
photophysical properties and DFT studies, Dye Pigm. 129 (2016) 174–185,
http://dx.doi.org/10.1016/j.dyepig.2016.02.026.
23] A.K. Sanap, K.K. Sanap, G.S. Shankarling, Synthesis and photophysical study of novel
coumarin
based
styryl
dyes,
Dye
Pigm.
120
(2015)
190–199,
http://dx.doi.org/10.1016/j.dyepig.2015.04.018.
24] A.B. Tathe, V.D. Gupta, N. Sekar, Synthesis and combined experimental and
computationalinvestigations on spectroscopic and photophysical propertiesof red
emitting
http://dx.doi.org/10.1016/j.dyepig.2015.03.023.
25] S.B. Phadtare, K.J. Jarag, G.S. Shankarling, Greener protocol for one pot synthesis of
coumarin styryl dyes, Dye Pigm. 97 (2013) 105–112,
http://dx.doi.org/10.1016/j.dyepig.2012.12.001.
3-styryl
coumarins,
Dye
Pigm.
119
(2015)
49–55,
[
[
[
26] S.N. Margar, N. Sekar, Red and near-infrared emitting bis-coumarin analogues based on
curcumin framework-synthesis and photophysical studies, J. Photochem. Photobiol. A
Chem. 327 (2016) 58–70, http://dx.doi.org/10.1016/j.jphotochem.2016.05.009.
27] A. Parvez, J. Meshram, V. Tiwari, J. Sheik, R. Dongre, M.H. Youssoufi, T.Ben Hadda,
Pharmacophores modeling in terms of prediction of theoretical physico-chemical
properties and verification by experimental correlations of novel coumarin derivatives
2
8