Aromatic aldehyde based chemosensors for fluoride and cyanide detection in organic and aqueous media: Ascertained by characterization, spectroscopic and DFT studies

Article abstract of DOI:10.1016/j.ica.2019.05.030

In the present investigation, a series of new aromatic aldehyde based chemosensors (S1-S4) have been sensibly designed and synthesized by the simple condensation reaction and their anion sensing properties were investigated. The compounds were characteriz

Full text of DOI:10.1016/j.ica.2019.05.030

Accepted Manuscript
Aromatic aldehyde based chemosensors for fluoride and cyanide detection in
organic and aqueous medium: Ascertained by characterization, Spectroscopic
and DFT Studies
Suresh N. Kodlady, B. Narayana, B.K. Sarojini, B.U. Gauthama
PII:
S0020-1693(19)30259-2
https://doi.org/10.1016/j.ica.2019.05.030
ICA 18931
DOI:
Reference:
Inorganica Chimica Acta
To appear in:
Received Date:
Revised Date:
Accepted Date:
25 February 2019
15 May 2019
16 May 2019
Please cite this article as: S.N. Kodlady, B. Narayana, B.K. Sarojini, B.U. Gauthama, Aromatic aldehyde based
chemosensors for fluoride and cyanide detection in organic and aqueous medium: Ascertained by characterization,
Spectroscopic and DFT Studies, Inorganica Chimica Acta (2019), doi: https://doi.org/10.1016/j.ica.2019.05.030
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Aromatic aldehyde based chemosensors for fluoride and cyanide detection in
organic and aqueous medium: Ascertained by characterization, Spectroscopic
and DFT Studies.
Suresh N Kodlady, B. Narayana*, B. K. Sarojini**, B. U. Gauthama.
*Department of Studies in Chemistry, Mangalore University, Mangalagangothri -574199,
Karanatka, India.
**Department of Industrial Chemistry, Mangalore University, Mangalagangothri -574199,
Karanatka, India.
Graphical abstract
DMSO Medium
DMSO: H2O (9:1) Medium
S1 F- CN-
S1 F-
CN-
-
-
-
-
R+Br , HsO , I ,
4
-
-
-
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
R+Br , HsO , I ,
-
4
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
CN
-
-
-
-
-
F
No , No , OH , Cl
-
-
-
-
2
3
No , No , OH , Cl
2
3
-
F
-
CN
250 300 350 400 450 500 550 600 650 700
250 300 350 400 450 500 550 600 650 700
Wavelength(nm)
Wavelength (nm)
ABSTRACT
In the present investigation, a series of new aromatic aldehyde based chemosensors (S1-
S4) have been sensibly designed and synthesized by the simple condensation reaction and their
anion sensing properties were investigated. The compounds were characterized by spectroscopic
1
13
techniques such as FT-IR, UV-Visible, H NMR, C NMR and ESI-MS. The probes exhibited
-
high sensitivity and selectivity towards fluoride and cyanide ions over the anions such as Br ,
HSO-4, Cl-, OH-, I-, NO-2 and NO-3 in dry DMSO and DMSO-water mixture (DMSO: H2O 9:1
1

v/v). The binding mechanism of fluorometric chemosensors with N-H-F and N-H-CN ion was
1
determined based on H NMR titration and were also theoretically supported by DFT (Density
functional theory) calculation. The stoichiometry and binding constant (Ka) of the host-guest
complexes formed were determined by the Benesi–Hildebrand (B–H) plot and Job's method
respectively. Finally, economically visible paper-based colorimetric “test stripes” of (S1-S4)
were fabricated to the detection of F- and CN- ions in 100% aqueous solution.
Keywords: Optical sensing, Fluoride ion, Cyanide ion, Colorimetric sensors, Organic medium,
organo-aqueous medium.
1. Introduction
Fluoride and Cyanide have distinctive chemical and biological properties, particularly
owing to its strong electro-negativity and small size. Considerable work has been designed for
the synthesis of selective receptors for sensing of anions. Lower concentrations of fluoride ion
have been devoted beneficial to avoid dental caries. At lower concentrations, the researchers are
discussing the health benefits of fluoride ions1-3. Among the most interested biologically
important anions, fluoride is of great importance because of its conventional role in the treatment
of osteoporosis and dental care4. In many cases, sensing of cyanide ion is indispensable in
environmental, biological and industrial research5-6, such as gold extraction, plastic
manufacturing, metallurgy and electroplating but at the same time it is highly noxious to human
health even at very small concentration due to its strong interactions with the active site of
cytochrome-oxidase7-8. For example, the fluoride ion is a major ingredient in hypnotics,
anesthetics, rat and cockroach poisons, psychiatric drugs and military nerve gases9-11. The
cyanide ion also detrimentally affects vascular, visual, central nervous, cardiac,
endocrine and metabolic functions. However, cyanide toxicity, large quantities of
cyanide salts are still widely used in industrial production such as metallurgy (1.5 million
tons per year), electroplating and the synthesis of fine chemicals. With the importance of the
industries, cosmetic goods of fluoride products, particularly food and food products, the
contamination of fluoride is more dangerous12. Therefore sensing of fluoride and cyanide ions in
the micromolar concentration in chemical, biological and environmental samples is outermost
2

important13-14
.
Although several methods including atomic absorption, voltametric,
potentiometric, electrochemical and ion exchange techniques have been explored these methods
do not offer a cost-effective, rapid and real-time monitoring system for fluoride and cyanide ions.
Fluoride is the smallest and the outmost important electronegative atom and has peculiar
chemical properties and can form the strongest hydrogen-bond donor15-16. In particular, the
synthesis of colorimetric anion sensors is most important why because visual detection can
propose qualitative and quantitative information at low levels and broadly used due to its low
cost or no requirements of specific equipment 17-18. Chemosensors are developed according to the
chromophore receptor general binomial19-20, which associate with the binding of a specific anion
substrate with receptor sites and a chromophore responsible for transforming the receptor anion
complex particularly participation into an optical signal when anions communicate with the
anion sensors through hydrogen bonding, electrostatic, hydrophobic interaction, coordination to
a metal center, or a combination of any two or more of these interactions. The anion sensor can
yield binding information either by its altered fluorescence, absorption spectra or both behaviors
21-25. The color variation can be associated with either structural or conformational changes in the
receptor moiety when a complex is formed or to the formation of charge transfer complex26.
These schemes are based upon N-H proton transfer from the donor entity to an anion, which
induce N-H deportation or π-electron delocalization27. Considerable efforts have been made to
develop hydrogen bonding receptors containing amine28, imidazole ion29, urea30-31, thiourea32-33
,
imine34, phenol35-36, pyrole37-37, hydroxyl groups39 and hydrazones40. In the present study, design
and synthesis of chemosensors based on reaction of aldehyde with amine, forming a Schiff base
(-C=N-) as a bridge was attempted 41.
In the synthesis of selective fluoride and cyanide ion chemosensors, aromatic aldehyde
receptor (S1-S4) was synthesized by the condensation of an aldehyde and 2,4 dinitrophenyl
hydrazine, this is an organic colorimetric chemosensor. The sensing of the fluoride and cyanide
ion was developed in DMSO and DMSO: H2O (9:1). This result shows the fluoride and cyanide
ions can be detected by the naked eye without interference from other anions based on N-H
proton transfer. The details of anion binding specific aromatic aldehyde with 2,4
dinitrophenylhydrazine (S1-S4) have been analyzed by UV-Visible and DFT studies. These
receptors (S1-S4) have high selectivity towards fluoride and cyanide ions in both spectroscopic
and absorption modes.
3

2. Experimental
2.1 Materials and methods.
All solvents and reagents (analytical grade and spectroscopic grade), all the anions in
tetrabutylammonium salts were obtained from Merck (India) and spectrochem Pvt. Limited
(India) and used without any further purification. All lab experiments were carried out at room
temperature. All UV-Visible spectra were carried out in DMSO and DMSO: H2O (9:1), NMR
spectra of the pure samples were recorded using a Bruker Advance (400 MHz)
spectrophotometer, where tetramethylsilane (TMS) was used as the internal standard and
DMSO-d6 and CDCl3 as the solvent. Resonance multiplicities were explained as s (singlet), d
(doublet), t (triplet), and m (multiplet). IR spectra were recorded on Bruker FT-IR spectrometer.
Mass spectra were analyzed on a Waters Micromass Q-Tofmicro spectrometer with ESI source.
UV-Vis spectra were recorded with a spectroquant pharo300 Spectrometer in standard 3.5 ml
quartz cells with 1 cm path length. The progress of the reaction was monitored by TLC plates.
Melting point was recorded on Raga melting-point apparatus in open capillaries42.
1-(2,4-dinitrophenyl)-2-((E)-3-phenylallylidene) hydrazine S1
Melting point=248-250 oC. δH (400 MHz; DMSO-d6 ): 7.0-7.11 (s, 2H, ArH), 7.34-7.50 (m, 3H,
ArH), 7.63-7.68 (t, 2H, ArH), 7.91-7.93 (d, 1H, J-9.2 Hz, ArH), 8.38– 8.40 (d, 1H, J-9.2 Hz,
13
ArH), 8.47–8.49 (d, 1H, J-6 Hz, ArH), 8.85 (s, 1H, ArH), 11.5(s, 1H, NH, ArH) (Fig-A4). C
NMR (DMSO-d6): δ (ppm): 116.12, 116.47, 122.86, 123.00, 124.81, 127.26, 127.75, 128.89,
129.07, 129.20, 129.37, 129.79, 136.98, 140.48, 151.76 (Fig-A5). LCMS (ESI-MS) m/z: [M-H]-
Calculated for C15H12N4O4, 312.09, Found: 310.95 (Fig-A3). FT-IR (KBr) ν (cm-1) =3305, 3276,
3096, 3033, 1945, 1585, 1505, 1491, 1421, 1302, 1275, 1253, 1217, 1125, 1106, 1063, 1027,
972, 916, 873, 824, 737, 681, 63 (Fig-A2). Yield=85%.
3-((2-(2,4-dinitrophenyl) hydrazono)methyl) pyridine S2
Melting point= 258-260o C. δH (400 MHz; DMSO-d6): 7.54 (dd, J1=4.4 Hz, J2=7.62 Hz, 1H,
ArH), 8.10-8.26 (m, 2H, ArH), 8.30-8.49 (m, 1H, ArH), 8.66 (d, J=3.2 Hz, 1H, ArH), 8.77 (S,
4

1H, ArH), 8.88 (S, 1H, ArH), 8.89 (S, 1H, ArH), 8.95 (S, 1H, ArH), 11.77 ( S, 1H, ArH) (Fig-
13
A17). C NMR (DMSO-d6): δ (ppm): 116.96, 122.89, 124.08, 129.14, 129.85, 133.82, 137.42,
144.31, 146.49, 148.83, 150.99 (Fig-A18). LCMS (ESI-MS) m/z: [M-H]- Calculated for
C12H9N5O4, 287.07, Found: 285.95 (Fig-A16). FT-IR (KBr) ν (cm-1) =3296, 3093, 1616, 1581,
1510, 1419, 1323, 1267, 1220, 1143, 1082, 966, 925, 894, 831, 806, 740, 721, 702, 655, 582,
555, 532 (Fig-A15). Yield=91%.
4-bromo-2-((2-(2,4-dinitrophenyl) hydrazono)methyl) phenol S3
Melting point= 265-267oC. δH (400 MHz; DMSO-d6: 6.89-6.91 (d, 1H, J=8.0 Hz, ArH), 7.45
(dd, J1=2.4 Hz, J2=8.4 Hz, 1H, ArH), 7.98-8.0 (d, J=8.0 1H, ArH), 8.11-8.813 (d, J=8.0,1H,
ArH), 8.38-8.39 (d, J=4.0, 1H, ArH), 8.86-8.92 (m, 2H, 2H, ArH), 10.54 (S, 1H ,ArH), 11.77 (S,
13
1H, ArH) (Fig-A35). C NMR (DMSO-d6): δ(ppm): 110.93, 116.95, 118.54, 122.46, 122.88,
127.85, 129.48, 127.72, 134.00, 137.03, 144.29, 144.34, 156.03 (Fig-A36). LCMS (ESI-MS)
m/z: [M-H]- Calculated for C13H9BrN4O5, 379.98, Found: 380.90 (Fig-A34). FT-IR (KBr) ν
(cm-1) = 3292, 3093, 1614, 1581, 1510, 1475, 1415, 1388, 1328, 1305, 1274, 1261, 1219, 1184,
1147, 1107, 1058, 943, 918, 881, 831, 817, 740, 723, 655, 624, 557, 528 (Fig-A33). Yield=85%.
2-((2-(2,4-dinitrophenyl) hydrazono)methyl) phenol S4
Melting point= 252-254oC. δH (400 MHz; DMSO-d6: 6.94 (dd, J1=7.6 Hz, J2=13.2 Hz, 2H,
ArH), 7.28-7.32 (t, 1H, ArH), 7.85-7.87 (d, 1H, J=6.82 Hz, ArH), 8.05-8.07 (d, 1H, J=8.0 Hz,
ArH), 8.37-8.39 (d, 1H, J=8.0 Hz, ArH), 8.87-8.97 (t, 2H, ArH), 10.21 (S, 1H, ArH), 11.73 (S,
1H, NH, ArH) (Fig-A53). 13C NMR (DMSO-d6): δ(ppm): 116.32, 116.64, 119.49, 120.07,
123.03, 126.41, 129.30, 129.72, 131.91, 136.78, 144.37, 146.55, 156.89 (Fig-A54). LCMS (ESI-
MS) m/z: [M-H]- Calculated for C13H10N4O5, 302.07, Found: 302.95 (Fig-A52). FT-IR (KBr) ν
(cm-1) = 3269, 3103, 1514, 1583, 1510, 1417, 1332, 1313, 1217, 1199, 1134, 1085, 962, 920,
821, 754, 715, 678, 648, 611, 528 (Fig-A51). Yield=81%.
2.2. UV-visible study of the receptor (S1-S4) with anions
For UV-Visible spectroscopic experiments of receptor (S1-S4) concentration (2.0×10-5
M) was prepared and different anion selectivity was investigated by the addition of different
5

equivalents of various anions (1.0×10-2 M) independently to (2.0×10-5 M) stock solutions (S1-S4)
in organic (DMSO) and organo-aqueous (DMSO: H2O, 9:1) medium and analyzed their
absorbance values from 250 to 700 nm. UV-visible titration experiments were recorded by
continues addition of different equivalents of the various anions through a micropipette added to
a 2ml (2.0×10-5 M) solution (S1-S4) in a cuvette in organic (DMSO) and organo-aqueous
(DMSO: H2O, 9:1) medium and the absorption spectra were recorded43.
2.2 NMR titration experiments
1
The proceeding results of H NMR titration studies determined the sensing of fluoride
and cyanide ions by S1 receptors through the development of receptor-fluoride and cyanide ion
complex. In order to confirm the mechanism of sensing, 1H NMR titration study was performed
with the receptor S1 in DMSO-d6 by the addition of 0.5, 1.0 and 1.5 equivalents of fluoride and
cyanide ions and the 1H NMR titration spectra were shown in Fig-12 and Fig-13.
2.3 Density functional theory calculations
The quantum chemical calculations of the density functional theory on the aromatic
aldehyde receptor were performed to support analyzing the optical behavior and method of
complexation of the aromatic aldehyde receptor with fluoride and cyanide ions. The geometry
optimizations and frontier molecular orbital properties of the molecule at DMSO solvent phase
performed by density functional theory with B3LYP exchange with 6-311G basics sets applying
Maestro-MS.
3.0 Results and Discussion
3.1 Synthesis
As shown in scheme 1. the receptors S1, S2, S3 and S4 were designed and synthesized
by a simple condensation reaction, by reacting 2,4 dinitrophenylhydrazine (0.430 g, 3 mmol)
with cinnamaldehyde (0.594 g, 3 mmol) receptor S1, pyridine 3-aldehyde (0.321 g,3 mmol)
receptor S2, 5-bromoalicyaldehdye (0.603 g,3 mmol), receptor S3 and salicylaldehyde (0.366
g,3 mmol) receptor S4, in ethanol (20ml) respectively. The reaction mixture was stirred at room
6

temperature for 12 hours. After completion of the reaction, the obtained yellow precipitate was
filtered and washed several times with ethanol to yield the pure receptors (S1-S4). The
completion of the pure product was confirmed by thin layer chromatography (TLC). All the
1
prepared simple Schiff bases (S1-S4) have been characterized by 13C NMR, H NMR, Mass
spectra and IR analysis of spectroscopic methods.
H
N
R-CHO
NH2
NH
R
12 hours, RT
N
O2N
NO2
H2O
O2N
NO2
O
O
O
Br
:
Where
R =
:
:
O
OH
OH
N
S1
S2
S3
S4
Scheme 1. Synthesis of receptor S1-S4.
3.2 Colorimetric detection of anions in organic and organo-aqueous medium
The naked eye response of receptor S1-S4 (2.0×10-5 M) against different anions such as
F-, Br-, I-, Cl-, OH-, HSO-4, NO-3, NO-2, F- and CN- (1.0×10-2 M) was first analyzed through
colorimetric chemosensor analysis in organic (DMSO) medium. It was established that among
the receptors S1-S4, only S1 displayed a drastic color change from yellow to purple with fluoride
and cyanide ions showed in Fig-A1 (information from ESI*), where as receptors S2-S4
displayed a visual color change from pale yellow to pink with fluoride and cyanide ions showed
in Fig-A6, A24, A42 (information from ESI*). No significant color changes of other anions such
as Br -, I-, Cl-, OH-, HSO-4, NO-3 and NO-2 ions under same conditions were noticed as shown in
Fig-1 and those related to receptors S2-S4 are showed in Fig-A8, A26, A44 (information from
7

ESI*). Receptor S1 colorimetric chemosensor analysis was also carried out in organo-aqueous
medium (DMSO: H2O, 9:1). It exhibited an optical color change from pale yellow to pink only
with fluoride and cyanide ions showed in Fig-A6, A24, A42 (information from ESI*), while no
-
visual response was observed on other anions such as Br , I-, Cl-, OH-, HSO-4, NO-3 and NO-2
ions as shown in Fig-2 and related receptor of S2-S4 showed in Fig-A8, A26, A44 (information
from ESI*).
I-
HSO-4
F-
Br-
CN-
S1
Cl-
OH-
NO-2
NO-3
Cl-
OH-
I-
NO-2 NO-3
CN-
HSO-4
Br-
S1
F-
Fig-1&2. Visual color change of receptor S1 (2.0×10-5 M in dry DMSO) after the addition of 3.3
equivalent and S1 (2.0×10-5 M in DMSO: H20, 9:1) with the addition of 4.5 equivalent of
different TBAF salts of anions (1×10-2 M).
3.3 UV-Visible spectroscopic titration of receptor S1 with Fluoride and Cyanide ions in DMSO
The visual interactions of receptor S1-S4 with fluoride and cyanide anions were
measured by UV-Visible spectroscopic absorption technique. The UV-Visible absorption
spectral changes of S1 upon the addition of fluoride and cyanide ions over the other anions are
shown in Fig-3 and those related to receptors S2-S4 were shown in Fig-A7, A25, A43
(information from ESI*). The UV-Visible spectrum of receptor S1 advertised a maximum
absorbance at 406 nm molar absorption coefficient logε = 5.83 which corresponds to the
intermolecular charge transfer (ICT) transition (n-π*) from N-atoms to the aldehyde moiety as
8

shown in Fig-3, on the addition of fluoride (0.0-3.3 equivalents) and cyanide (0.0-3.75
equivalents) the visual color of receptor changed from pale yellow to purple showed in Fig-A1
(information from ESI*) and other receptors S2-S4 showed drastic color changes from pale
yellow to pink showed in Fig-A6, A24, A42 (information from ESI*).
A new peak was developed at 517 nm and 515 nm resulting from the complex between
receptor S1 with fluoride and cyanide ions. It indicated the bathochromic shifts of λICT= 111 nm
and 109 nm (Fig-3). In this case N-H….F- and N-H….CN- is a relatively good electron donor than
free N-H in the intermolecular charge transfer (ICT) transition in receptor S144-46, while the
fluoride and cyanide ions were bound via H-bonding interaction from the amine group of
receptor S1, the electron cloud density of electron rich amine fragment was further increased
which developed the charge transfer interaction between electron rich and electron deficient
DNP moiety.
The UV-Visible titration, of receptor S1 was carried out in DMSO medium by taking
different equivalent of F- (0.0-3.3 equivalent) and CN- (0.0-3.75 equivalent). Upon addition of
fluoride and cyanide ions, the absorption peak at 402 nm was shifted to 517 nm which was
attributed to the charge transfer between F- and CN- with high acidic –NH unit of the receptor S1
(Fig-3)47-49. The final colorimetric UV-Visible titration confessed a clear isosbestic point of 452
nm which determined the formation of a strong complex between receptor S1 with F- and CN-.
Absorption spectra of S1 (2.0×10-5 M) in the presence of fluoride ion (up to 3.3 equivalent of
TBA-F) and cyanide ion (up to 3.75 equivalent of TBA-CN) in DMSO showed in Fig-9. All
other receptors S2-S4 produced a comparable UV-Visible spectral changes with fluoride and
cyanide showed in Fig-A9, A27, A45 (information from ESI*). Extended variation method was
used to determine the stoichiometric ratio of the receptor, fluoride and cyanide ions guest. In Fig-
11, Job’s plot of receptor S1 (1×10-4 M) with F- and CN- in DMSO medium shows a maximum at
a mole fraction of 0.5. These results were shows that the receptor S1 binds with fluoride and
cyanide anion with a 1:1 stoichiometric ratio to form complex and receptor S2-S4 showed in Fig-
A14, A32, A50 (information from ESI*).
9

3.4 UV-Visible spectroscopic titration of receptor S1 with Fluoride and Cyanide ions in Organo-
aqueous medium
The sensing capacity of the receptor S1 was carried out in DMSO: H2O (9:1, V/V)
solution. The optical color changes were seen for F- and CN- ions on binding with receptor S1
even in existence of protic solvent of H2O as shown in Fig-6. The protic solvent of H2O contest
with anion binding sites of the receptor nearby annoying the cooperation between receptor and
anion. However, the receptor S1 demonstrated the capability of water molecules to bind with
anions in aqueous medium and recommended the hydrogen-bond interaction between anions and
receptor S1. UV-Visible spectrum was recorded on stepwise addition up to 5.0 equivalent of F-
and 5.25 equivalent of CN- ions in the DMSO: H2O (9:1, V/V). The solution displayed changes
in UV-Visible absorbance spectrum from F- and CN- ions shown in Fig-6 and other receptors S2-
S4 showed in Fig-A7, A25, A43 (information from ESI*). The stepwise addition of 0.0-5.0
equivalents of F- ions (1×10-2 M) to the receptor (2.0×10-5 M) increases its absorbance band from
405 nm to 512 nm with sharp isosbestic point of 449 nm, showing regular interaction with
receptor S1 and F- ions with a bathochromic red shift of 107 nm and with drastic color changes
from pale yellow to pink showed in Fig-A14, A32, A50 (information from ESI*). On the other
hand incremental addition of 0.0-5.25 equivalents of CN- ions to the DMSO: H2O (9:1, V/V)
(2.0×10-5 M) displayed new absorbance band at 509 nm, resulting in bathochromic shift of 104
nm with the isosbestic point at 449 nm which convey that a new species is formed in response to
the interaction with receptor S1 and anions shown in Fig-6.
When similar set of UV-Visible spectroscopic titration was carried in organo-aqueous
medium (DMSO: H2O, 9:1, V/V), it was interesting to observe that, the receptor S1 advertised a
drastic color changes from pale yellow to pink only with fluoride and cyanide ion while no color
change was observed with Br-, I-, Cl-, OH-, HSO-4, NO-3 and NO-2 ions shown in Fig-10.
3.5 Determination of stoichiometry, binding constant, the limit of detection and limit of
quantification
Bensi-Hilderbrand (B-H) plot was sketched between 1/(A-A0) and 1/[Mn+]2 according to
the B-H equation 1. The receptor S1 upon incremental addition of the F- and CN- showed 1:2
binding stoichiometric ratio in DMSO and DMSO: H2O, 9;1 shown in Fig-5 & Fig-8 and related
receptor S2-S4 showed in Fig-A12, A13, A30, A31, A48, A49 (information from ESI*). The
10

binding constant between receptor S1-F- and CN- were calculated and given in the table below
Table 2.
Linearity plotted between absorbance v/s concentration of F- and CN- in molar shown in
Fig-4 & Fig-7 and remaining receptor S2-S4 showed in Fig-A10, A11, A28, A29, A46, A47
(information from ESI*). A good relationship between absorbance and concentration with the
R2>0.99. The limit of detection & limit of quantification was calculated using the equation given
bellow and showing in Table 2.
퐴 ‒ 퐴0
1
Equation 1.
퐾 =
×
퐴푚푎푥 ‒ 퐴
[푀푛 + ]푛
Where
K = is the association constant
A0= is the absorbance of receptor in the absence of guest.
A = is the absorbance recorded in the presence of an added guest.
Amax = is absorbance in the presence of added [Mn+]max.
[Mn+] n = concentration of fluoride and cyanide ion with binding ratio.
Limit of Detection = 3.3* Standard deviation of calibration curve (SD) / Slope.
Limit of quantification = 10* Standard deviation of calibration curve (SD) / Slope.
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
3.75
517nm
515nm
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
406nm
406nm
3.3
0.0
CN-Equiv
0.0
F- Equiv
250 300 350 400 450 500 550 600 650 700
250 300 350 400 450 500 550 600 650 700
Wavelength (nm)
Wavelength (nm)
11

Fig-3. UV-Visible absorption changes of receptor S1 (2.0×10-5 M) upon addition of (0.0 to 3.3
equivalent) of TBA-F and (0.0 to 3.75 equivalent) of TBA-CN (1.0×10-2 M) in DMSO.
2.00
1.60
1.20
0.80
0.40
0.00
1.60
1.20
0.80
0.40
0.00
0E+00
1E-05
2E-05
3E-05
0E+00
1E-05
2E-05
3E-05
[CN-] M
[F-] M
Fig-4. Calibration curve for the determination of detection limit of receptor S1 with Fluoride and
Cyanide ions in DMSO.
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
1.0
0.0
0.0E+00
5.0E+10
1.0E+11
0.0E+00
5.0E+10
1.0E+11
1 / [ F-]2
1 / [ CN-]2
Fig-5. Inset: B–H plot for the titration of receptor S1 with F- and CN- ion in DMSO.
12

405nm
405nm
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
5.0
0.0
512nm
509nm
5.25
-
CN Equiv
0.0
F- Equiv
250 300 350 400 450 500 550 600 650 700
250 300 350 400 450 500 550 600 650 700
Wavelength (nm)
Wavelength
Fig-6. UV-Visible absorption changes of receptor S1 (2.0×10-5 M) upon addition of (0.0-5.0
equivalent) of TBA-F and (0.0 to 5.25 equivalent) of TBA-CN (1.0×10-2 M) in DMSO: H2O
(9:1).
1.20
1.00
0.80
0.60
0.40
0.20
0.00
1.20
1.00
0.80
0.60
0.40
0.20
0.00
0E+00
1E-04
0E+00
1E-04
[CN-] M
[F-] M
Fig-7. Calibration curve for the determination of detection limit of receptor S1 with fluoride and
cyanide ion in DMSO: H2O (9:1, v/v).
13

12.0
10.0
8.0
12.0
10.0
8.0
6.0
6.0
4.0
4.0
2.0
2.0
0.0
0.0E+00
0.0
0.0E+00
5.0E+10
1.0E+11
5.0E+10
1.0E+11
1 / [F-]2
1 / [CN-]2
Fig-8. Inset: B–H plot for the titration of receptor S1 with F- and CN- ion in DMSO: H2O (9:1).
-
-
-
-
-
-
R+Br , HsO , I ,
-
R+Br , HsO , I ,
4
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
4
CN
-
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
F
-
-
-
-
-
-
2
-
-
No , No , OH , Cl
No , No , OH , Cl
2
3
3
-
F
-
CN
250 300 350 400 450 500 550 600 650 700
250 300 350 400 450 500 550 600 650 700
Wavelength(nm)
Wavelength (nm)
Fig-10. UV-Visible absorption
changes receptor S1 (2.0×10-5 M)
upon addition of (5.0 equivalent) of
TBAF and (0.0 to 5.25 equivalent)
of TBACN (1.0×10-2 M) in DMSO:
H2O (9:1).
Fig-9. UV-Visible Absorption spectra
of receptor S1 (2.0×10-5 M) in the
absence and presence of different
anions (3.3 equivalent of TBA-F and
3.75 equivalent of TBACN (1.0×10-2
14

-
CN
0.27
0.26
0.25
0.24
0.23
0.22
0.21
0.20
-
F
0.32
0.30
0.28
0.26
0.24
0.22
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
-
-
[receptor]/[receptor]+[CN ]
[recptor] /[recptor]+[F ]
Fig-11. Job’s plot for complexation of receptor S1 (517 nm) and (515 nm) with F- and CN- ions
determined by UV-visible experiments in (DMSO) organic medium.
Table1. Selected absorption spectra of receptors S1-S4 (2.0×10-5 M) in DMSO and DMSO: H2O
(9:1, V/V) medium in the presence of F- and CN- ions (1.0×10-2 M) in different equivalent
Medium of
Detection
UV-Visible
band in nm
without F-
and CN-
UV-Visible
band in nm
with F- ion
UV-
Bathochromic
Shift in
Visible
color
change
Visible
band in
nm with
CN- ion
Receptor
visible band
in nm
F-&CN-
DMSO
DMSO
DMSO
406
390
404
111 &109
S1
S2
S3
S4
S1
517
504
508
515
502
506
Pale yellow
to purple
114 &112
102 &104
Pale yellow
to pink
Pale yellow
to pink
DMSO
405
405
499
512
497
509
94 &92
Pale yellow
to pink
DMSO:H2O
(9:1.V/V)
107&104
Pale yellow
to pink
DMSO: H2O
(9:1.V/V)
389
499
498
110&109
Pale yellow
to pink
S2
15

DMSO: H2O
(9:1.V/V)
406
403
502
493
503
492
97&96
90&89
Pale yellow
to pink
S3
S4
DMSO: H2O
(9:1.V/V)
Pale yellow
to pink
Table 2. Association constant and Binding constant, Limit of Detection and Limit of
Quantification of receptor S1-S4 in the presence of fluoride and cyanide ions.
Association
constant M-1 constant in
M-1
Binding
LOD in
ppm
LOQ in ppm
R+Anions
2.1×105
2.58×109
0.268
0.8
S1+TBAF(DMSO)
2.9×105
1.0×105
1.0×104
8.7×104
2.9×105
1.1×105
1.8×105
7.4×104
3.0×104
1.6×105
2.9×104
3.7×105
2.5×105
1.9×105
1.1×105
3.19×109
3.4×109
1.59×109
1.2×109
7.6×108
4.0×109
1.02×109
2.49×109
3.75×109
1.69×109
5.61×109
7.0×109
3.8×109
4.73×109
5.33×109
0.314
0.258
0.292
0.60
0.20
0.20
0.10
0.12
0.19
0.230
0.33
0.27
0.5
1.0
S1+TBACN(DMSO)
S2+TBAF(DMSO)
0.80
0.90
0.55
0.18
0.60
0.30
0.40
0.60
0.70
1.0
S2+TBACN(DMSO)
S3+TBAF(DMSO)
S3+TBACN(DMSO)
S4+TBAF(DMSO)
S4+TBACN(DMSO)
S1+TBAF(DMSO:H2O, 9:1)
S1+TBACN(DMSO:H2O, 9:1)
S2+TBAF(DMSO:H2O, 9:1)
S2+TBACN(DMSO:H2O, 9:1)
S3+TBAF(DMSO:H2O, 9:1)
S3+TBACN(DMSO:H2O, 9:1)
S3+TBAF(DMSO:H2O, 9:1)
S3+TBACN(DMSO:H2O, 9:1)
0.80
0.15
1.70
1.40
0.558
0.451
16

3.6 1H NMR titration study of receptor S1 with Fluoride and Cyanide ions
S1
S1+0.5 eq F-
S1+1.0 eq F-
S1+1.5eq F-
Fig-12. Titration of S1 with TBA-F in DMSO-d6 as monitored by 1H NMR spectroscopy.
17

Fig-13. Titration of S1 with TBA-CN in DMSO-d6 as monitored by 1H NMR spectroscopy.
The chemosensor property exhibited by the receptor S1 was observed by UV-visible
spectroscopy. In order to analyze the sensing mechanism of the receptor S1 with fluoride and
1
cyanide, the H NMR titration study was investigated shown in Fig-A12 and Fig-A13. In 2,4
dinitrophenylhydrazine the signal corresponds to –NH proton was observed at 8.85 ppm, when
18

the 2,4 DNP attached with aromatic aldehyde the signal was observed at 11.56 ppm in the
presence of N-H proton. This is due to the existence of ICT between 2,4 DNP and aromatic
1
aldehyde. H NMR titration of receptor S1 observed with tetrabutylammonium fluoride and
cyanide ion in DMSO-d6. The addition of 0.5 equivalent of fluoride the comparable (11.26 ppm)
–NH proton peak was shifted to slightly up field and the addition of 1.0, 1.5 equivalent of
1
fluoride resulted, disappeared –NH proton in the H NMR spectra. On the other hand, the
receptor S1 complex with CN- in 1H NMR titration, the addition of 0.5, 1.0 and 1.5 equivalent of
CN- the corresponding (11.56 ppm)–NH proton had completely disappeared. The mechanism is
that –NH proton moiety of the receptor S1 interacts with F- and CN- through hydrogen bonding
and formed by the more F- and CN- in the interaction inducing proton transfer reaction and
density of the electron increased shown in scheme 2.
This leads to ICT in the whole system and red shift in the absorption on the addition of F-
and CN-. At the meantime, the electron density of nitro aromatic aldehyde ring was gradually
increased and the hydrogens of aromatic ring shifted upfield automatically. Therefore, color
change can be showing to the formation of hydrogen bonding between –NH moiety and F-, CN-
ions.
19

X-
H
N
H
N
=F- or CN-
X
N
O
N
O
O
O
N
O
N
O
N
O
N
O
-HX
N
N
N
N
O
O
O
O
N
N
O
N
N
O
O
O
N
N
O
O
N
O
N
O
Scheme 2. Interaction of fluoride respectively cyanide anions with the receptor S1 including
mesomeric formulae of deprotonated S1.
3.7 Computational study of receptor S1-S4 with fluoride and cyanide ion.
To understand the photophysical properties of the receptors S1-S4 and its calculation
with fluoride and cyanide ions were carried out by theoretical methods using Maestro-MS
calculation. The receptor (S1-S4) were optimized and complexes with the electronic ground and
excited state through Density Functional Theory (DFT) calculation using the B3LYP/6-311G
basis set with the fluoride and cyanide ions observed by using Maestro-MS software (Fig-14).
The additional information about the mechanism of interaction between S1 complexes
with anions was obtained from the typical transition energy diagram for the HOMO and LUMO
of the receptor S1 with its complex with fluoride and cyanide ions as shown in Fig-14 and
related receptor S2-S4 showed in Fig-A19, A37, A55 (information from ESI*). The more
disturbed HOMO layer with DNP moieties and also the distribution of aldehyde moiety. On the
deprotonated species, mostly HOMO layer was located with aldehyde moieties and LUMO was
distributed in aldehyde and DNP moieties. Therefore, binding of fluoride and cyanide with
receptor S1 and the electron density through extended Л-conjugation, which leads to the
homogenous distribution throughout the molecule. The aspect had been well explained in the
ICT 50-51
.
20

The bathochromic shift of the absorption band of receptor S1 when binding with fluoride
and cyanide ions might be further understood in terms of increase of the potential energy of its
HOMO & LUMO shown in Fig-14. The energy gap between HOMO and LUMO of receptor S1
decreased on its binding with fluoride and cyanide. The fluoride and cyanide ions would prefer
electron deficient LUMO more rather than HOMO. Therefore, on binding with fluoride and
cyanide the potential energy of the LUMO slightly decreased moderately and finally directed
towards the narrowing of the energy gap between HOMO &LUMO, which was ultimately
responsible for the red shift of absorption maximum of receptor S1 complex with fluoride and
cyanide.
A) LUMO S1
B) LUMO S1+F-
C) LUMO S1+CN-
ΔE=1.4530 ev
ΔE=5.9276 ev
ΔE=1.9319 ev
ΔE=5.2836 ev
ΔE=1.8078 ev
ΔE=5.3171ev
ΔE=7.3806 ev
ΔE=7.2155 ev
ΔE=7.1249 ev
HOMO S1
HOMO S1+F-
HOMO S1+CN-
Fig-14. HOMO’S and LUMO’S diagrams for (A) receptor S1, (B)receptor S1+F-, (C) receptor
S1+CN- obtained by the B3LYP/6-311G method.
21

3.8 Practical applications in real sample analysis of Receptor S1
Further study, practical applications in real sample analysis of receptor S1 was carried out
by qualitative determination of fluoride and cyanide ions in commercially usable products such
as toothpaste and mouthwash. Mouthwash & toothpaste sample was weighed 20 mg in 1ml by
dissolving distilled water52. Finally, a drop of commercially useable mouthwash and toothpaste
was added into the receptor S1, a drastic color change from pale yellow to A) orange & B) pink
correlation as shown in Fig-15. The UV-visible absorption spectra recorded with receptor S1 in
the presence of mouthwash and toothpaste showing similar charge transfer absorption band as
observed in the case of fluoride and cyanide ions are shown in the Fig- 15. All other receptors
(S2-S4) analysis showed in Fig-A20, A21, A38, A39, A56, and A57 (information from ESI*).
S1
A
B
Fig-15. The color change of the receptor S1 (2.0×10-5M) upon addition of a drop of (A)
mouthwash and (B) toothpaste.
1.6
Toothpaste
S1
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Mouthwash
250 300 350 400 450 500 550 600 650 700
Wavelength(nm)
Fig-16. Absorption spectra of receptor S1 (2.0×10-5 M) upon addition of a drop of mouthwash
and toothpaste.
22

3.9 Practical application
In the present investigation of receptor S1, test strips were prepared by using Whatman-
40 test paper immersing into DMSO solution and dried in the hot air oven. Upon this light-
yellow colored strip was observed and which was then dipped into an aqueous solution of (A)
TBA-F and TBA-CN of different concentration shown in Fig-17 and Fig-18, receptor S2-S4
showed in Fig-A22, A23, A40, A41, A58, A59 (information from ESI*), this showed drastic
color changes. Finally, we concluded this kind of application is more efficient and less
expensive, new receptor will be more advantageous in sensing of these anions in real life
application.
300ppm
500ppm
100ppm
S1
Fig-17. Color changes of test papers prepared using receptor S1 for detecting F- ions in aqueous
solution with different concentration.
23

500ppm
S1
100ppm
300ppm
Fig-18. Color changes of test papers prepared using receptor S1 for detecting CN- ion in aqueous
solution with different concentration.
Conclusion
To illustrate, the simple and efficient colorimetric sensors, receptor S1-S5 based on
aromatic aldehyde with –NH as a hydrogen donor. To analyze the UV-visible absorption
spectroscopy of receptor (S1-S4) showing higher selectivity for fluoride and cyanide ions
without any distinct color from other anions, the bathochromic shift was observed on maximum
absorption. The receptor S1 shows a dramatic color change from pale yellow to purple and (S2-
S4) pink upon addition of fluoride and cyanide in DMSO medium and S1-S4 shows drastic color
1
change from yellow to pink in organo-aqueous (DMSO: H2O, 9:1) medium. H NMR titration
can be done the reaction between receptor S1-S4 with fluoride and cyanide which indicate the
delocalization of electron in the system and intermolecular charge transfer would increase
exhibiting UV-Visible absorption spectra red shift significantly. Finally, the quantum mechanical
calculation through DFT well supported the experimental findings.
24

Acknowledgement
One of the authors would like to thank Mangalore University for providing research
fellowship. Authors gratefully acknowledge SAIF, IISC Bangalore for providing NMR
characterization and DST-PURSE, Mangalore University for providing characterization
facilities.
25

Reference.
[1] N. Chen, Z. Zhang, C. Feng, D. Zhu, Y. Yang, N. Sugiura, J. Hazard. Mater. 186 (2011)
863–868.
[2] WHO, Guidelines for Drinking Water Quality Incorporating 1st and 2nd Addenda
Recommendations, third ed, World Health Organization, Geneva, Switzerland. 2008.
[3] X. Xiong, J. Liu, W. He, T. Xia, P. He, X. Chen, K. Yang, A. Wang, Environ. Res. 103
(2007) 112–116.
[4] Jung Oh Huh, Youngkyu Do, and Min Hyung Lee. Organometallics. 27 (2008) 1022–
1025.
[5] Ki. Cheol Song, Kang Mun Lee, Nguyen Van Nghia, Woo Young Sung, Youngkyu Do,
and Min Hyung Lee. Organometallics. 32 (2013) 817−823.
[6] Syed S. Razi, Rashid Ali, Priyanka Srivastava, Arvind Misra, Tetrahedron Letters. 55
(2014) 1052–1056.
[7] K.W. Kulig, Cyanide Toxicity, U. S. Department of Health and Human Services, Atlanta,
GA, 1991.
[8] A. Dhillon, M. Nairb, D. Kumar, Analytical methods for determination and sensing of
fluoride in biotic and abiotic sources: a review, Anal. Methods. 8 (2016) 5338-5352.
[9] Todd W. Hundnall, Ching-Wen Chiu. 42,2 (2009) 388-397.
[10] Stephen J. Butler. Chem. Commun. 51 (2015) 10879-10882.
[11] Muhammad Moazzam Naseera, b and Klaus Jurkschata, Chem. Commun.53 (2017)
8122–8135.
[12] Sudeshna Chandra, Ales Ruziicka, Petr Svec, Heinrich Lang Analytica Chimica
Acta. 577 (2006) 91–97.
[13] George Rajendra Kumar and Pakkirisamy Thilagar. Dalton Trans. 43 (2014)7200-7207.
[14] Youngmin Kim, Hyun-Sue Huh, Min Hyung Lee, Ivan L. Lenov, Haiyan Zhao, and
FranÅois P. Gabba, Chem. Eur. J. 17 (2011) 2057 – 2062.
[15] Kirk, K. L. Biochemistry of the Halogens and Inorganic Halides; Plenum Press: New
York. (1991) 58.
[16] Kleerekoper, M. Endocrinol. Metab. Clin. North Am. 27 (1998) 441.
[17] R. Vilar, Angew. Chem. Int. Ed. 42 (2003) 1460–1477.
[18] Y. M. Hijji, B. Barare, A.P. Kennedy, R. Butcher, Sens. Actuators B. 136 (2009) 297–
302.
[19] Atsushi Kawachi, Atsushi Tani, Junpei Shimada, and Yohsuke Yamamoto. J. Am. Chem.
Soc. 130 (2008) 4222-4223.
[20] Amos B. Smith, Org. Lett. 14 (2012) 1-2.
[21] J. Li, H. Lin, Z. Cai, H. Lin, Spectrochim. Acta A. 72 (2009) 1062–1065.
[22] G.V. Zyryanov, M. A. Palacios, J. P. Anzenbacher, Angew. Chem. Int. Ed. 46 (2007) 1.
[23] T. P. Lin, C.Y. Chen, Y.S. Wen, S. S. Sun, Inorg. Chem. 46 (2007) 9201–9212.
[24] J. F. Zhang, C.S. Lim, S. Bhuniya, B.R. Cho, J.S. Kim, Org. Lett. 13 (2011) 1190–1193.
26

[25] H. S. Jung, H. J. Kim, J. Vicens, J.S. Kim, Tetrahedron Lett. 50 (2009) 983–987.
[26] T. S. Snowden, E.V. Anslyn, Curr. Opin. Chem. Biol. 3 (1999) 740–746.
[27] M.Cametti, K. Rissanen, Chem.Commun. 20 (2009) 2809–2829.
[28] B. Liu, H. Tian, J. Mater. Chem. 15 (2005) 2681–2686.
[29] K. Chellappan, N. J. Singh, I. C. Hwang, J.W. Lee, K.S. Kim, Angew. Chem. Int. Ed. 44
(2005) 2899–2903.
[30] D. Esteban-Gomez, L. Fabbrizzi, M. Liechelli, J. Org. Chem. 70 (2005) 5717–5720.
[31] A.B. Descalzo, K. Rurack, H. Weisshoff, R. Martinez-Manez, M.D. Marcos, P. Amoros,
K. Hoffmann, J. Soto, J. Am. Chem. Soc. 127 (2005) 184–200.
[32] D. A. Jose, D.K. Kumar, B. Ganguly, A. Das, Tetrahedron Lett. 46 (2005) 5343–5346.
[33] D. H. Lee, J.H. Im, J.H. Lee, J.I. Hong, Tetrahedron Lett. 43 (2002) 9637–9640.
[34] S. Devaraj, D. Saravanakumar, M. Kanadaswamy, Tetrahedron Lett. 48 (2007) 3077–
3081.
[35] D. H. Lee, K.H. Lee, J.I. Hong, Org. Lett. 3 (2001) 5–8.
[36] X. Zhang, L. Guo, F.Y. Wu, Y.B. Jiang, Org. Lett. 5 (2003) 2667–2670.
[37] P. Anzenbacher, K. Jursikova, J. L. Sessler, J. Am. Chem. Soc. 122 (2000) 9350–9351.
[38] C. I. Lin, S. Selvi, J.M. Fang, P.T. Chou, C.H. Lai, Y.M. Cheng, J. Org. Chem. 72 (2007)
3537–3542.
[39] D. A. Jose, P. Kar, D. Koley, B. Ganguly, W. Thiel, H.N. Ghosh, A. Das, Inorg. Chem.
46 (2007) 5576-5584).
[40] Y. H. Qiao, H. Lin, H.K. Lin, J. Incl. Phenom. Macrocycl. Chem. 59 (2007) 211–215.
[41] R. L. Sheng, P.F. Wang, W.M. Liu, X.H. Wu, S.K. Wu, Sens. Actuator B. 128 (2008)
507– 511.
[42] Z. Lin, Y. Zhao, C. Duan, B. Zhang, Z. Bai, Dalton Trans. 30 (2006) 3678–3684.
[43] Archana Singh , Suban K. Sahoo , Darshak R. Trivedi. 188 (2018) 596-610.
[44] X.b Zhuang, W. Liu, J. Wu, H. Zhang, P. Wang, Spectrochim. Acta A. 79 (2011) 1352–
1355.
[45] J. You, H. Jeong, H. Seo, S. Jeon, Sens. Actuators B. 146 (2010) 160–164.
[46] R. Vilar, Angew. Chem. Int. Ed. 42 (2003) 1460-1477.
[47] Y. M. Hijji, B. Barare, A.P. Kennedy, R. Butcher, Sens. Actuators B. 136 (2009) 297–
302.
[48] J. Li, H. Lin, Z. Cai, H. Lin, Spectrochemica. Acta A. 72 (2009) 1062–1065.
[49] S. Saravana Kumar, S. Bothra, S.K. Sahoo, S.K. Ashok Kumar, J. Fluorine Chem. 164
(2014) 51-57.
[50] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J. R. Cheeseman,
J.A. Montgomery Jr, T. Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A. Petersson, H.
Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T.
Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox, H.P. Hratchian,
J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev,
27

A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K. Morokuma, G.A.
Voth, P. Salvador, J. J. Dannenberg, V.G. Zakr-zewski, S. Dapprich, A.D. Daniels, M.C.
Strain, O. Farkas, D. K. Malick, A.D. Rabuck, K. Raghavachari, J.B. Foresman, J.V.
Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J. Cioslowski, B. B. Stefanov, G. Liu, A.
Liashenko, P. Piskorz, I. Komaromi, R. L. Martin, D. J. Fox, T. Keith, M.A. Al-Laham,
C.Y. Peng, A. Nanayakkara, M. Challacombe, P. M.W. Gill, B. Johnson, W. Chen, M.W.
Wong, C. Gonzalez, J.A. Pople, Gaussian 03, Revision C02, Gaussian Inc., Pittsburgh,
PA, 2004.
[51] X. Yang, L. Zheng, L. Xie, Z. Liu, Y. Li, R. Ning, G. Zhang, X. Gong, B. Gao, C. Liu.
207 (2015) 9-24.
[52] S. Suganya, J. S. Park and S. Velmathi, Sensors and Actuators B. 190 (2014) 679-684.
28

Highlights
 Colorimetric responses of S1-S4 to anions in organic (DMSO) and organo: aqueous
(DMSO:water) medium were visible to the naked eye
 Detection of F- and CN- by S1-S4 was monitored by means of UV-vis and test stripes
techniques.
 The S1-S4 ha an excellent sensitivity with the detection limits under micro molar
concentration
 The method was validated and applied for the detection F- ion in real samples( mouth
freshener and toothpaste).
29