Reversible Addition of Cyanide to Triphenylamine Attached Difluoroboron β-Diketonate Facilitated Selective Colorimetric and Fluorimetric Detection of Cyanide Ion

Article abstract of DOI:10.1002/ejoc.201901820

Nucleophilic addition of cyanide on a new triphenylamine attached difluoroboron β-diketonate {4-[4-(diphenylamino) phenyl]-2,2-difluoro-6-methyl-2H-1,3,2-dioxaborinin-1-ium-2-uide (C4)} breaks the conjugation readily and thereby offers efficient and selec

Full text of DOI:10.1002/ejoc.201901820

A Journal of
Accepted Article
Title: Reversible Addition of Cyanide to Triphenylamine Attached
Difluoroboron β-Diketonate Facilitated Selective Colorimetric and
Fluorimetric Detection of Cyanide ion
Authors: Duraiyarasu Tamilarasan, Ramalingam Suhasini,
Viruthachalam Thiagarajan, and Rengarajan Balamurugan
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To be cited as: Eur. J. Org. Chem. 10.1002/ejoc.201901820
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Supported by

European Journal of Organic Chemistry
10.1002/ejoc.201901820
FULL PAPER
Reversible Addition of Cyanide to Triphenylamine Attached
Difluoroboron β-Diketonate Facilitated Selective Colorimetric and
Fluorimetric Detection of Cyanide ion
Duraiyarasu Tamilarasan,§ [a] Ramalingam Suhasini,§ [b] Viruthachalam Thiagarajan* and Rengarajan
[b]
Balamurugan*[a]
Dedication ((optional))
[
a]
Dr. R. Balamurugan and Mr. D. Tamilarasan,
School of Chemistry
University of Hyderabad
Prof. C. R Rao Road
P.O. Central University, Hyderabad, Telangana state, India.
E-mail: bala@uohyd.ac.in
Homepage: http://chemistry.uohyd.ac.in/~rb/
Dr. V. Thiagarajan and Ms. R. Suhasini
School of Chemistry
[
b]
Bharathidasan University
Palkalaiperur, Tiruchirappalli, Tamil Nadu, India.
E-mail: v.thiagarajan@bdu.ac.in
Supporting information for this article is given via a link at the end of the document.
Both the authors contributed equally to this work
§
Abstract: Nucleophilic addition of cyanide on a new triphenylamine
attached difluoroboron β-diketonate (4-(4-(diphenylamino) phenyl)-
methods have been developed for quantitative detection of
titrimetric,[8]
electrochemical,
and chromatographic analyses.[11]
[9]
cyanide
ion
like
[10]
2,2-difluoro-6-methyl-2H-1,3,2-dioxaborinin-1-ium-2-uide
(C4))
spectrophotometric,
breaks the conjugation readily and thereby offers efficient and
selective detection of cyanide. A rational mechanism based on UV-
However, these methods have different limitations such as large
time consumption, high cost and requirement of highly skilled
operators. In recent days, development of fluorescent probes as
optical sensors for selective and sensitive detection of cyanide ion
has been explored with cost-effectiveness and simple-to-use
alternatives in focus.[12] These sensor systems have their
advantages like operational simplicity, fast detection and
feasibility for naked-eye detection which eventually creates an
excellent tool for on-site analysis.[13] Different sensors have been
reported so far based on hydrogen bonding interaction,
supramolecular self-assembly, coordination of cyanide ion with a
1
11
19
Vis, fluorescence, NMR ( H, B, and F) and HRMS analysis and
DFT calculations have been proposed. The detection limit was found
to be 0.36 μM. A test strip assay using the title compound has also
-
been applied to detect CN in aqueous solution for real-time
applications.
Introduction
metal ion, boronic acid derivatives, nucleophilic addition reaction,
deprotonation, etc.[14] Among these, particular interest has been
devoted to designing fluorescent probes based on oxazine,
pyrylium, indolium, pyridinium, acridinium, imidazole, dicyano-
Development of small molecules for anion recognition has
received considerable attention over the last 25 years due to their
influential role in far-ranging biological, environmental, and
chemical applications.[1] Among the several anions, cyanide ion
vinyl
group,
carbazole,
quinoline,
salicylaldehyde,
-
(
CN ) is a highly toxic inorganic anion, which is still extensively
trifluoroacetamide derivatives, and other highly electron-deficient
carbonyl compounds for selective detection of cyanide ion.[15]
Difluoroboron β-diketonate complexes have gained much
attention in recent years due to their unique photophysical
properties and have been shown to possess a wide range of
applications.[16] In this manuscript, we present a triphenylamine
attached difluoroboron β-diketonate based fluorescent sensor
used in various industrial processes such as electroplating, gold
mining, tanning, metallurgy, plastic manufacturing and production
of synthetic fibers and resins.[2] It is also found in agricultural
products such as cassava roots and bamboo shoots.[3] Cyanide
ions are generated by hydrolysis of phosphate-based chemical
warfare agents.[ Throughout the world, consumption of cyanide
is as much as 1.5 million tons per year.[5] Cyanide ion has a
greater affinity to cytochrome c oxidase to forms a complex in the
human bloodstream which results in respiratory arrest and finally
leads to death when consumption exceeds 0.05 mg kg-1 of body
weight.[6] The maximum permissive level of cyanide ion in
drinking water is specified as 1.9 μM (70 ppb) by the World Health
Organization (WHO).[7] Thus efficient and selective detection of
cyanide ion is a highly desirable task. Various conventional
4]
(
C4) for highly selective and sensitive detection of cyanide ion
over other anions. This simple probe has an interesting feature
that nucleophilic addition on the carbonyl can disturb the
conjugation and, consequently, the optical properties. This
system is different from the conventional dicyanovinyl based
Michael acceptors used for the sensing of cyanide ion.[15o, 15r, 17] In
the dicyanovinyl systems, the nucleophilic addition of cyanide ion
takes place at the -carbon and breaks the conjugation of the
1
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European Journal of Organic Chemistry
10.1002/ejoc.201901820
FULL PAPER
Absorption and emission spectra of C4
chromophore group with the cyano groups completely and hence
no ICT is observed between them. In the system presented in this
manuscript the nucleophilic addition of cyanide ion takes place at
the 1,3--ketonate carbon with the blue shift of ICT between the
The absorption and emission spectra of C4 in different solvents
with varying polarity are shown in figure 1, and their
corresponding photophysical data are gathered (Table ST1,
Supporting Information). C4 showed a strong and intense
absorption band around 425 nm in all the solvents investigated
which is ascribed to intramolecular charge transfer (ICT) from
triphenylamine donor moiety to the difluoroboron acceptor moiety
within the molecule. As the solvent polarity is increased within
polar aprotic solvents from acetone to dimethyl sulfoxide a slight
red shift was observed (423 to 432 nm) which indicates the
stabilization of ICT transition.The emission spectra presented in
figure 1b is also red shifted (530 to 567 nm) with increase in
solvent polarity as similar to absorption spectra due to the
stabilization of ICT process within the molecule.
amine and the BF
2
groups. In addition, this system offers
reversibility in the presence of excess water. Interaction of
cyanide ion with C4 is accompanied by the formation of an
anomalous emission and color change from yellow to colorless
via intramolecular charge transfer mechanism.
Results and Discussion
Synthesis and Characterization: The synthetic route for the
preparation of C4 is simple and it was obtained in high yield by
following the Scheme 1.[18] Incorporation of BF
by refluxing 1, 3-diketone substrate
2
was carried out
with BF ·OEt in
3
3
2
dichloromethane. The structure of the compound C4 was
confirmed by H NMR, 13C NMR, 11B and 19F NMR, ATR-IR and
HRMS spectra (Figure S7-S12).
1
a) 0.3
0.2
0.1
0.0
300
350
400
450
500
Wavelength (nm)
b)
250
200
150
Scheme 1. The synthetic route of C4.
a) 6.0x104
Acetone
Acetonitrile
DMF
100
DMSO
Ethanol
4
4
.0x10
.0x10
50
4
2
0
350
400
450
500
Wavelength (nm)
0
.0
3
50
375
400
425
450
475
500
525
Wavelength (nm)
Figure 2. Absorption and emission spectra of C4 (7 μM) in the presence and
absence of CN (0-400 μM) in acetonitrile/water (98:2) solution.
b)
-
Acetone
Acetonitrile
DMF
DMSO
Ethanol
1
.0
.8
.6
.4
.2
.0
0
0
0
0
0
Absorption and emission spectral studies in the presence
and absence of anions
The absorption and emission spectra of C4 in the presence and
absence of cyanide ions (tetrabutylammonium cyanide) in
2 2
acetonitrile:H O (98:2) are shown in figure 2. The acetonitrile:H O
4
50
500
550
600
650
700
750
(
98:2) system was chosen for cyanide ion sensing based on the
Wavelength (nm)
photophysical results obtained from a series of experiments with
different fractions of water in acetonitrile.[18] Appreciable change
in absorption and emission properties was noted in solvents
systems containing less than 10% of water in acetonitrile. On
Figure 1. Absorption and emission spectra of C4 in various solvents.
2
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European Journal of Organic Chemistry
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FULL PAPER
increasing the concentration of CN-, the intensity of ICT
Selectivity and effect of anion interference
absorption band centered at 425 nm decreases along with the
formation of a new absorption peak at 320 nm. The formation of
an isosbestic point at 364 nm indicates the 1:1 interaction
To evaluate the selectivity of cyanide ion over other anions, the
optical response of C4 in 98% acetonitrile with various anions in
excess were evaluated using absorption and emission spectral
-
-
b
e
t
w
e
e
n
t
h
e
C
4
a
n
d
C
N
.
T
h
e
s
t
o
i
c
h
i
o
m
e
t
r
y
b
e
t
w
e
e
n
C
4
a
n
d
C
N
was again confirmed from the Job’s plot. As shown in the Job’s
plot curve (Figure S15, supporting information), the measured
absorbance variation at 320 nm reached a maximum value when
-
-
-
-
-
studies (Figure 3). Among the tested anions (CN , F , Cl , Br , I ,
AcO-, ClO - 3-, HSO - IO - PF - HCO -
PO as their
4
,
4
4
,
4
,
6
,
3
)
-
tetrabutylammonium salts at 10 equivalents excess concentration
(60 µmol), the probe responded only to the cyanide ion with a
remarkable color change from yellow to colorless. The addition
of fluoride ion in excess also caused a slight influence on the
absorption spectrum of C4, but with much lower sensitivity than
the molar ratio of [C4]/([C4] + [CN ]) was 0.50, which indicated an
-
1
:1 interaction between C4 and CN . At a higher concentration of
-
CN , the absorption band at 425 nm disappeared completely and
the new band at 320 nm was only visible. This is due to the fact
that electron density at acceptor moiety increases after the
-
-
that of CN . The absorption and emission spectra of C4 in the
nucleophilic addition of CN which results in the formation of a new
presence and absence of F- are depicted in figure S16
ICT state leading to the complete disappearance of the old ICT
band at 425 nm. This change in the ICT behavior resulted in a
color change from yellow to colorless indicating that compound
(
Supporting Information). In contrast to the absorption spectrum,
there is no change in the fluorescence spectrum in the presence
-
-
-
of F . It was the case with the other anions as well. F is highly
solvated in water and loses its basicity due to hydration in
acetonitrile-water mixture. The slight change observed in the
absorption spectrum may be due to the change in the solvation
around the C4 molecule. The comparatively lower hydration
energy for the cyanide ion (ΔHhyd = -64 kJ/mol) than that of the
C4 could serve as a colorimetric probe to detect CN with naked
eye (Figure 2a). The fluorescence spectra of C4 in
acetonitrile:H O (98:2) were recorded by exciting at the isosbestic
2
point (272 nm) after every addition of aliquots of
tetrabutylammonium cyanide solution of known concentration to
it. As shown in figure 2b, C4 is non-fluorescent at this excitation
-
fluoride ion (ΔH = -505 kJ/mol) may be the reason for the higher
wavelength in the absence of CN . In contrast, the presence of
hyd
selectivity and sensitivity of C4 towards cyanide ion.[
19]
-
CN led to the formation of a new emission peak centered at 402
nm. The gradual addition of cyanide ion led to fluorescence
enhancement at 402 nm due to the formation of a new ICT state.
2
2
50
00
a)
0.3
0.2
0.1
0.0
C4
C4+Perchlorate
C4+Acetate
C4+Phosphate
C4+Bromide
C4+Iodide
C4+Fluoride
C4+Cyanide
C4+Chloride
C4+Hydrogen Sulphate
C4+Periodate
C4+Hexafluorophosphate
C4+Bicarbanate
150
100
5
0
0
-
C4
C4 without
C4 with CN
C4 with
alone
-
+
all other
anions
-
CN + all
CN alone
other anions
300
350
400
450
500
550
600
-
Figure 4. Competitive experiments in the C4-CN system with interfering anions
Wavelength (nm)
(λex = 272 nm). Selectivity profiles of C4 (7 µM) in the presence of 60 µM of
-
-
-
-
-
- 3- - - - -
various anions (F , Cl , Br , I , AcO , ClO , PO , HSO , IO , PF , HCO ) in
4 4 4 4 6 3
-
acetonitrile/water (98:2) with or without CN .
C4
b)
500
400
300
200
100
0
C4+Perchlorate
C4+Acetate
C4+Phosphate
C4+Bromide
C4+Fluoride
C4+Cyanide
C4+Chloride
C4+Hydrogen Sulphate
C4+Periodate
C4+Hexafluorophosphate
C4+Bicarbanate
To further explore the utility of C4 as an ion-selective fluorescent
-
sensor for CN , the effect of other anion interference on the
-
detection of CN was carried out upon the addition of 10
equivalents of other anions individually and all other anions
combined in 98% acetonitrile solution (Figure 4). These results
indicate that other anions did not induce any significant changes
C4+Iodide
-
in the presence of CN . Therefore, C4 could be used as a
fluorescent and colorimetric sensor for CN- detection with
excellent selectivity and specificity. From the fluorescence
titration, the detection limit of cyanide ion using C4 was found to
be 0.36 μM.
350
400
450
500
Wavelength (nm)
Figure 3. Absorption and emission spectra of C4 (7 μM) with various anions (60
μM) in acetonitrile/water (98:2) solution.
3
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European Journal of Organic Chemistry
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FULL PAPER
In order to elucidate the actual interaction between the cyanide
ion and C4, NMR titrations have been carried out with different
aliquots of tetrabutylammonium cyanide from 0.1 to 2.0
1
11
19
equivalents by H, B, F NMR spectroscopy in CDCl
CDCl was chosen for this experiment because the peaks due to
acetonitrile and water in CD
3
. Solvent
3
3
CN appeared prominently in the
-
aliphatic region of C4. Upon increasing the concentration of CN
from 0 to 2.0 equivalents a gradual decrease in intensity of the
olefinic -CH and CH protons of C4 and increase in intensity of
3
the new peaks at 5.03 and 1.55 ppm were noted. The olefinic
proton signal at 6.4 ppm and the methyl peak at 2.3 ppm
Figure 5. Chemical structures of control compounds used to understand the
-
CN sensing mechanism of C4.
-
completely disappeared in the presence of excess CN (Figure 7).
The same spectral pattern was observed in 19F spectra as well
In order to understand the binding mechanism and high selectivity
Figure 8). However, 11B NMR was not informative (Figure S19).
(
-
of C4 towards CN , similar kinds of photophysical studies were
carried out with two control compounds DPDO and TPA (Figure
5). There is no significant change in the absorption and emission
spectra of control compounds with all the anions studied including
-
CN (Figure S17 and S18, Supporting Information)
.
It clearly
indicates that difluoroboron moiety plays a crucial role in the
sensing of CN-.
Detection mechanism
The detection mechanism (Scheme 2) was elucidated by both
experimental ( H, 11B and 19F NMR titrations, HRMS spectra) and
1
1
theoretical studies. In the H-NMR of C4, the olefinic proton (-H
a
)
and methyl protons (-CH3a) appeared at 6.58 ppm and 2.22 ppm
respectively in the acetonitrile-d solvent. Upon the addition of two
equivalents of tetrabutylammonium cyanide, both the protons -H
and -CH3b experienced a considerable upfield shift to 5.03 and
.55 ppm respectively. The methyl protons were merged with -
CH - protons of tetrabutylammonium cyanide (Figure 6). Besides,
3
Figure 7. 1H NMR spectra of titration experiment with tetrabutylammonium
cyanide on C4 in CDCl3.
b
1
2
These results indicate that the transformation of C4 to C4-CN-,
which was further confirmed by HRMS analysis. The molecular
some changes of peak positions in the aromatic region were
observed.
ion peak of C4 appeared at 400.1291 corresponding to
[M+Na] . In the presence of 10 equivalents of CN-
+
C
22
H18BF
2
NO
2
,
C4 in acetonitrile:water (98:2) solution showed signal assignable
-
to the formation of the C4+CN adduct at m/z, 403.1449 (Fig. S20,
Supporting Information). Based on the NMR titrations, a plausible
structure for the adduct, as in Scheme 2 has been proposed. In
-
an organic solvent, strong nucleophile CN can attack the carbonyl
carbon to give the intermediate (I) in which the olefinic and methyl
protons is expected to experience upfield shifts. To our surprise,
the actual NMR spectral characteristics of C4 were restored by
Scheme 2. A plausible mechanism of addition of CN- to C4 and reversibility
upon addition of excess water.
-
the addition of excess water to C4-CN . This could be due to the
-
-
leaving of CN from the C4+CN adduct which in turn generates
-
the starting compound (Scheme 2). The solvation of CN in water
is perhaps the reason for the above reverse reaction. The H and
F NMR titrations reveal that there is no fluoride displacement in
the presence of CN . There are a few reports on cyanide ion
sensors based on BODIPY and related compounds. The sensing
mechanism proposed in the present study is different from those
that are reported in these reports.[20]
1
1
9
-
Figure 6. 1H NMR spectra of compound C4 in acetonitrile-d
and after addition
3
-
of 2 Equiv. CN in acetonitrile-d
3
.
4
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European Journal of Organic Chemistry
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FULL PAPER
gap between HOMO and LUMO is accountable for the blue-
shifted emission in the presence of CN-.
-
Figure 10. Test strip detection of CN in water.
Figure 8. 19F NMR spectra of titration experiment C4 with tetrabutylammonium
3
cyanide in CDCl .
-
Test strip detection of CN ion
Computational Studies
A test-strip-based assay was developed to achieve the detection
-
of CN in neat aqueous solution and thereby it could be used for
-
To further investigate the CN detection mechanism using C4,
density functional theory (DFT) calculations were performed at
the B3LYP/6-31G* level of the Gaussian 09 program to
in situ/on-site detection. We chose Whatman filter paper because
this matrix ensures the probe is physisorbed well so that there is
no leaching of the hydrophobic probe molecules in water.
Whatman test strips were dipped into the acetonitrile solution of
C4 and left to dry in air. It was then immersed in 10 M aqueous
solution of tetrabutylammonium cyanide. As seen in the Figure
[21]
understand their electronic structures. Optimization of C4 and
C4+CN was performed in the gas phase. The calculated
molecular orbitals and their energies are shown in Figure 9.
-
10, significant color change from yellow to colorless was observed
immediately. It proved that the test strips could be applied to
-
detect CN qualitatively in water for rapid detection. The test strip
experiments conducted at various concentrations were not useful
as the color change was not prominent at lower concentrations.
Conclusions
In summary, we have successfully developed a Donor-Acceptor
system based on triphenylamine donor and difluoroboron -
diketonate acceptor. Nucleophilic addition of cyanide ion on
difluoroboron -diketonate completely changes the photophysical
-
properties of C4 and thereby offers selective detection of CN both
-
colorimetrically and fluorimetrically. C4 senses the CN with a
detection limit of 0.36 μM without any interference from other
anions. Test strip detection in water and immediate response
make C4 a promising system for sensing of CN-.
Figure 9. HOMO and LUMO of C4 and C4+CN-.
Experimental Section
In C4, the highest occupied molecular orbital (HOMO) is localized
mainly onto the triphenylamine (TPA) unit, and the lowest
unoccupied molecular orbital (LUMO) is localized mostly on the
dioxaborine ring and one of the phenyl ring from TPA moiety
Materials and methods
-
connected to it. Interestingly, the nucleophilic addition of CN with
Toluene and methanol were dried over sodium metal before use.
Dichloromethane was freshly distilled over CaH
recorded on 400 MHz and 500 MHz spectrometers in CDCl
with tetramethylsilane (TMS) as the internal standard. IR spectra were
recorded on an ATR-IR spectrometer. The progress of the reactions was
monitored by TLC and visualized under UV and Iodine chamber. Column
chromatography was performed using silica gel 100-200 mesh, using ethyl
acetate and hexane mixture as eluent. Titration studies were carried out in
C4 leads to complete reversal of HOMO to LUMO and LUMO to
HOMO. HOMO is localized mainly on the dioxaborine ring and
LUMO is localized on the two phenyl rings perpendicular to the
plane of the molecule. It confirms that the nucleophilic addition of
. 1H and 13C spectra were
and CD CN
2
3
3
-
CN with C4 leads to the formation of a new ICT state, which in
turn responsible for the enhancement in new ICT emission peak
-
upon increasing the CN concentration. The increase in the energy
10-mm quartz cell at room temperature. Tetrabutylammonium salts of the
5
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European Journal of Organic Chemistry
10.1002/ejoc.201901820
FULL PAPER
-
-
-
-
-, CH
-
3
) were purchased from reputed chemical companies and used
-
3-, HSO
-, IO -
, PF -
respective anions (F , Cl , Br , I , ClO
HCO
4
3
COO , PO
4
4
4
6
,
The limit of detection (LOD) for C4 was calculated from a
fluorescence titration. To determine the S/N ratio, the
-
fluorescence intensity of C4 without CN was measured ten times
without any further purification. All spectral studies were carried out in
HPLC solvents. High-resolution mass spectra (HRMS) were obtained from
micro mass ESI-TOF MS and Accurate-Mass Q-TOF LC/MS system. UV-
vis and fluorescent measurements were carried out on a Cary 300 Bio and
Jasco FP-6300 spectrophotometer, respectively. NMR titrations were
and the standard deviation of blank measurements was
o
determined to be 0.0572. The fluorescence intensity plot [I/I -1]
-
varies almost linearly vs. the concentration of CN in the range of
4
4 – 200 µM. The limit of detection was then calculated from the
following equation,
3
carried out using C4 in CDCl solution. Different equivalents (0.1 to 2) of
3
tetrabutylammonium cyanide (from a stock of 10 mM in CDCl ) were added
to a C4 solution and the spectra were recorded.
LOD = 3σ/k
Synthesis of C4
Where σ is the standard deviation of blank measurements, m is
the slope obtained from the plot of [I/I -1] verses CN-
Compounds 2 and 3 were prepared by following methods from previously
o
reported procedures.[18]
concentration. The limit of detection was obtained to be 0.36 µM
-
which was lower than the WHO limit of 1.9 µM for CN in drinking
water. This indicates that C4 was highly sensitive for the detection
1-(4-(Diphenyl amino) phenyl) ethan-1-one (2). To a stirred solution of
-
of CN anion.
triphenylamine (2.5 g, 10.20 mmol) in dry dichloromethane (30 mL), acetyl
chloride (0.8 mL, 12.23 mmol) was added dropwise for 0.5 h at 0˚C.
Anhydrous AlCl (1.6 g, 12.23 mmol) was added in portionwise. Then, the
3
reaction was brought to room temperature and stirred for 12 h. The
reaction mixture was then poured into ice cooled water and neutralized
Acknowledgments
with 10% aqueous Na
The organic layers were combined and dried over anhydrous Na
solvent was removed using a rotavapor. The crude was purified by column
chromatography using 20% EtOAc/hexanes to get the product as a pale
2
CO
3
solution and extracted with dichloromethane.
SO . The
RS and VT thank SERB, DST, New Delhi [Grant no.
YSS/2014/00026] for financial support. This work was also
financed by the Department of Science and Technology
Nanomission[Grant no. DST/NM/NB-2018/10(G)]. DT thanks
UGC for a fellowship. RB thanks SERB [EMR/2017/003142/OC],
UPE-II and DST-PURSE for financial assistance.
2
4
1
yellow solid; Yield = 80%, R
MHz, CDCl
m, 6H), 6.98 (d, J = 8.8 Hz, 2H), 2.52 (s, 3H); 13C NMR (100 MHz, CDCl
f
= 0.46 in 1:5 EtOAc/hexanes; H NMR (400
3
): δ 7.79 (d, J = 8.8 Hz, 2H), 7.31 (t, J = 8.4 Hz, 4H), 7.16-7.10
(
3
):
δ 196.6, 152.2, 146.5, 130.0, 129.7, 126.0, 124.7, 119.7, 26.4 (Figure S1
and S2).
Keywords: Triphenylamine • difluoroboron β-diketonate •
Fluorescent sensor • Colorimetric sensor • Cyanide ion • Test
strip detection
1-(4-(Diphenyl amino) phenyl) butane-1,3-dione (3). Ethyl acetate (0.4
mL, 3.91 mmol) was added to a stirred solution of NaH (0.18 g, 4.35 mmol)
and 1-(4-(diphenyl amino) phenyl) ethan-1-one 2 (0.25 g, 0.87 mmol) in
2
dry toluene (5 mL) at room temperature under N atmosphere. The solution
[
1]
a) S. A. Boer, E. M. Foyle, C. M. Thomas, N. G. White, Chem. Soc. Rev.
019, 48, 2596-2614; b) P. A. Gale, E. N. W. Howe, X. Wu, M. J. Spooner,
was refluxed for 21 h. The reaction mixture was cooled at room
temperature then neutralized with dil. HCl and extracted with EtOAc (2×20
mL). The combined organic phase was dried over anhydrous sodium
sulphate. The product was purified by column chromatography using 20%
2
Coord. Chem. Rev. 2018, 375, 333-372; c) P. Molina, F. Zapta, A.
Caballero, Chem. Rev. 2017, 117, 9907-9972; d) P. A. Gale, E. N. W.
Howe, X. Wu, Chem 2016, 1, 351-422; e) P.A. Gale, N. Busschaert, C.
J. E. Haynes, L. E. Karagiannidis, I. L. Kirby, Chem. Soc. Rev. 2014, 43,
of EtOAc/hexanes mixture. Yellow solid (0.23 g, yield = 80%,); R
f
= 0.77 in
1
1:5 EtOAc/hexanes; H NMR (400 MHz, CDCl
3
): δ 16.39 (s, 1H), 7.73 (d,
205-241; f) N. Busschaert, C. Caltagirone, W. V. Rossom, P. A. Gale,
J = 8.8 Hz, 2H), 7.33-7.29 (m, 4H), 7.17-7.13 (m, 6H), 7.01 (d, J = 8.8 Hz,
Chem. Rev. 2015, 115, 8038–8155; g) V. Thiagarajan, P. Ramamurthy,
D. Thirumalai, V. T. Ramakrishnan, Org. Lett. 2005, 7, 657-660.
a) D. A. Dzombak, R. S. Ghosh, G. M. Wong-Chong, Cyanide in Water
and Soil: Chemistry, Risk and Management, CRC Press, 2005, 41-54; b)
C. Young, L. Tidwell, C. Anderson, Cyanide: Social Industrial and
Economic Aspects, The Minerals, Metals, and Materials Society,
Warrendale, 2001.
2
1
3
H), 6.09 (s, 1H), 2.16 (s, 3H); 13C NMR (100 MHz, CDCl
): δ 191.6, 183.7,
3
51.7, 146.6, 129.6, 128.5, 125.8, 124.5, 120.3, 95.7, 25.4; IR (neat): 
[
2]
1
027, 2969, 1738, 1584, 1488, 1217, 772 cm ; HRMS (ESI): calcd for
+
C
22
H
19NO
2
[M+Na] 352.1308, Found 352.1306 (Figure. S3-S6).
4
-(4-(Diphenylamino)phenyl)-2,2-difluoro-6-methyl-2H-1,3,2-
dioxaborinin-1-ium-2-uide (C4). To a stirred solution of the 1,3-diketone
substrate 3 (0.06 g, 0.18 mmol) in dry dichloromethane (3 mL), BF ·OEt
0.027 mL, 0.22 mmol) was added dropwise at room temperature and
maintained for another 0.5 h. The colour of the reaction mixture changed
instantly to red during the addition of BF ·OEt . The reaction was
[3]
[4]
[5]
[6]
A. P. Cardoso, E. Mirione, M. Ernesto, F. Massaza, J. Cliffc, M. R.
Haquee, J. H. Bradburye, J. Food Compos. Anal, 2005, 18, 451-460.
M. Burnworth, S. J. Rowan, C. Weder, Chem. Eur. J. 2007, 13, 7828-
7836.
3
2
(
3
2
a) T. F. Cummings, Occup. Med. 2004, 54, 82-85; b) J. Hamel, Crit. care
Nurse, 2011, 31, 72-82.
quenched with 0.2N aqueous NaOH solution and extracted with
dichloromethane solution. The crude product was further purified using
a) J. L. Way, Pharmacologic Aspests of Cyanide and its Antagonism,
(Eds.: B. Vennesland, E. F. Comm, J. Knownles, J. Westly, F. Wissing),
Academic Press, London, 1981, pp. 29-49; b) K. W. Kulig, Cyanide
Toxicity, U.S. Department of Health and Human Services, Atlanta, GA,
1991.
column chromatography. Red solid; MP: 209-211˚C; Yield = 97%, R
f
= 0.26
1
in 1:5 EtOAc/hexanes; H NMR (500 MHz, CDCl
3
): δ 7.87 (d, J = 9.0 Hz,
2
6
1
H), 7.37 (t, J = 8.0 Hz, 4H), 7.24-7.18 (m, 6H), 6.93 (d, J = 9.0 Hz, 2H),
.40 (s, 1H), 2.31 (s, 3H); 13C NMR (125 MHz, CDCl
): δ 188.2, 180.9,
54.5, 145.3, 131.3, 130.0, 126.7, 126.1, 118.3, 96.0, 24.3; 11B (160 MHz,
): δ 0.91; 19F (470 MHz, CDCl
): δ -140.1; IR (neat):  3036, 1544,
cm ; HRMS (ESI): calcd for C22 NO
M+Na] 400.1291, Found 400.1291 (Figure. S7-S12).
3
[7]
Guidelines for Drinking-Water Quality, World Health Organization, 4th
Edn, 2017.
CDCl
3
3
-
1
1489, 1336, 754, 697, 517
H18BF
2
2
[8]
[9]
T. Suzuki, A. Hioki, M. Kurahashi, Anal. Chim. Acta 2003, 476, 159-165.
a) A. A. C. Riojas, A. Wong, G. A. Planes, M. D. P. T. Sotomayor, A. L.
Rosa-Toro, A. M. Baena-Moncada, Sens. Actuators B 2019, 287, 544-
550; b) G. Ding, H. Zhou, J. Xu, X. Lu, Chem. Commun. 2014, 50, 655-
+
[
Limit of Detection:
657.
6
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European Journal of Organic Chemistry
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FULL PAPER
[
10] a) H. M. Al-Saidi, S. A. Al-Harbi, E. H. Aljuhani, M. S. El-Shahawi, Talanta
016, 159, 137-142; b) D. Cacace, H. Ashbaugh, N. Kouri, S. Bledsoe,
[18] a) J. Z. Patel, T. Parkkari, T. Laitinen, A. A. Kaczor, S. M. Saario, J. R.
Savinainen, D. Navia-Paldanius, M. Cipriano, J. Leppanen, I. O.
Koshevoy, A. Poso, C. J. Fowler, J. T. Laitinen, T. Nevalainen, J. Med.
Chem. 2013, 56, 8484−8496; b) M. Liu, L. Zhai, J. Sun, P. Xue, P. Gong,
Z. Zhang, J. Sun, R. Lu, Dyes Pigm. 2016, 128, 271-278.
2
S. Lancaster, S. Chalk, Anal. Chim. Acta 2007, 589, 137-141; c) B.
Deepa, N. Balasubramanian, K. S. Nagaraja, Anal. Lett. 2003, 36, 2865-
2
874; d) M. W. Scoggins, Anal. Chem. 1972, 44, 1294-1296.
11] a) S. Kage, T. Nagata, K. Kudo, J. Chromatogr. B: Biomed. Appl. 1996,
75, 27-32; b) S. L. Youso, G. A. Rockwood, J. P. Lee, B. A. Logue, Anal.
[
[19] a) S. Saha, A. Ghosh, P. Mahato, S. Mishra, S. K. Mishra, E. Suresh, S.
Das, A. Das, Org. Lett. 2010, 12, 3406; b) N. Kumari, S. Jha, S.
Bhattacharya, J. Org. Chem. 2011, 76, 8215-8222; c)C. E. Housecroft,
A. G. Sharpe, In Inorganic Chemistry, 3rd ed.; Pearson Education, Ltd.:
Harlow, 2008, 537.
6
Chim. Acta 2010, 677, 24-28; c) B. Desharnais, G. Huppe, M. Lamarche,
P. Mireault, C. D. Skinner, Forensic Sci. Int. 2012, 222, 346-351; d) R.
Jackson, B. A. Logue, Anal. Chim. Acta 2017, 960, 18-39; e) T. T.
Christison, J. S. Rohrer, J. Chromatogr. A 2007, 1155, 31-39.
[20]
a) R. Guliyev, S. Ozturk, E. Sahin, E. U. Akkaya, Org. Lett. 2012, 14,
1528-1531; b) Y. Yu, T. Shu, C. Fu, B. Yu, D. Zhang, H. Luo, J. Chen, C.
Dong, J. Lumin. 2017, 186, 212–218; c) L. Wang, L. Li, D. Cao, Sens.
Actuators B 2017, 241, 1224–1234; S. Sarveswari, A. J. Beneto, A. Siva,
Sens. Actuators B 2017, 245, 428-434.
[
[
12] a) F. Wang, L. Wang, X. Chen, J. Yoon, Chem. Soc. Rev. 2014, 43, 4312-
4324; b) Z. Xu, X. Chen, H. N. Kim, J. Y. Yoon, Chem. Soc. Rev. 2010,
39, 127-137; c) X. Wu, B. Xu, H. Tong, L. Wang, Macromolecules 2011,
44, 4241-4248; d) L. Hou, F. Li, J. Guo, X. Zhang, X. Kong, X. T. Cui, C.
Dong, Y. Wang, S. Shuang, J. Mater. Chem. B 2019, 7, 4620-4629.
13] a) P. Gholamzadeh, G. M. Ziarani, N. Lashgari, A. Badiei, A. Shayesteh,
M. Jafari, J. Fluoresc 2016, 26, 1857-1864; b) Shaily, A. Kumar, N.
Ahmed, Ind. Eng. Chem. Res. 2017, 56, 6358-6368; c) R. Dalapati, S.
Nandi, H. Reinsch, B. K. Bhunia, B. B. Mandal, N. Stock, S. Biswas, Crys.
Eng. Comm. 2018, 20, 4194-4201; d) J. Dasgupta, P. K. Ma, Anal. Chim.
Acta, 2010, 673, 117-125.
[21] M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J.
R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson,
H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino,
G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda,
J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T.
Vreven, J. A. Montgomery, J. E. Peralta, F. Ogliaro, M. Bearpark, J. J.
Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J.
Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J.
Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B.
Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann,
O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L.
Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J.
Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J.
V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian, Inc. Wallingford CT, 2009.
[
14]
a) Q. Lin, T. T. Lu, X. Zhu, T. B. Wei, H. Li, Y. M. Zhang, Chem. Sci.
2
016, 7, 5341-5346; b) S.-S. Sun, A. J. Lees, J. Am. Chem. Soc. 2000,
22, 8956-8967; c) H. Miyaji, J. L. Sessler, Angew. Chem. Int. Ed. 2001,
13, 154-157; d) L. Yao, J. Zhou, J. Liu, W. Feng, F. Li, Adv. Funct. Mater.
012, 22, 2667-2672; e) B. B. Shi, P. Zhang, T. B. Wei, H. Yao, Q. Lin,
1
1
2
Y. M. Zhang, Chem. Commun. 2013, 49, 7812-7814; f) W. Cao, X. Zheng,
D. Fang, L. Jin, Dalton Trans. 2014, 43, 7298-7303; g) P. Isar, M. R. Rao,
M. Ravikanth, Eur. J. Org. Chem. 2018, 24, 3095-3104; h) T. Liu, X. Liu,
M. A. Valencia, B. Sui, Y. Zhang, K. D. Belfield, Eur. J. Org. Chem. 2017,
27, 3957-3964.
[
15] a) F. Garcia, J. M. Garcia, B. Garcia-Acosta, R. Martinez-Manez, F.
Sancenon, J. Soto, Chem. Commun. 2005, 22, 2790-2792; b) M. Sun, S.
Wang, Q. Yang, X. Fei, Y. Li, Y. Li, RSC Adv. 2014, 4, 8295-8299; c) J.
Li, J. Gao, W. Xiong, P. Li, H. Zhang, Y. Zhao, Q. Zhang, Chem. Asian.
J. 2014, 9, 121-125; d) P. Wang, Y. Yao, M. Xue, Chem. Commun. 2014,
50, 5064-5067; e) Y. Zhang, D. Li, Y. Li, J. Yu, Chem. Sci. 2014, 5, 2710-
2716; f) M. K. Bera, C. Chakraborty, P. K. Singh, C. Sahu, K. Sen, S.
Maji, A. K. Das, S. Malik, J. Mater. Chem. B, 2014, 2, 4733-4739; g) Y.
Yue, F. Huo, C. Yin, J. Chao, Y. Zhang, Sens. Actuators B 2015, 212,
451–456; h) F. Huo, J. Kang, C. Yin, J. Chao, Y. Zhang, Sens. Actuators
B 2015, 215, 93-98; i) K. Xiong, F. Huo, C. Yin, Y. Yang, J. Chao, Y.
Zhang, M. Xu, Sens. Actuators B 2015, 220, 822-828; j) T. Liu, F. Huo,
J. Li, F. Cheng, C. Yin, Sens. Actuators B 2017, 239, 526-535; k) C. Yina,
F. Huo, M. Xu, C. L. Barnes, T. E. Glass, Sens. Actuators B 2017, 252,
592-599; l) Q. Zou, F. Tao, H. Wu, W. W. Yu, T. Li, Y. Cui, Dyes Pigm.
2019, 164, 165- 173; m) P. R. Lakshmi, R. Manivannan, P. Jayasudha,
K. P. Elango, Anal. Methods, 2018, 10, 2368-2375; n) P. Jayasudha, R.
Manivannan, S. Ciattini, L. Chelazzi, K. P. Elango, Sens. Actuators B,
2017, 242, 736-745; o) E. Jeong, S. Yoon, H. S. Lee, A. Kumar, P. S.
Chae, Dyes Pigm. 2019, 162, 348-357; p) Q. Li, Z. Wang, W. Song, H.
Ma, J. Dong, Y. Quan, X. Ye, Z. Huang, Dyes Pigm. 2019, 161, 389-395;
q) P. B. Pati, S. S. Zade, Eur. J. Org. Chem. 2012, 33, 6555-6561; r) Z.
Li, Y. Dai, Z. Lu, Y. Pei, Y. Song, L. Zhang, H. Guo, Eur. J. Org. Chem.
2019, 22, 3614-3621. s) N. Kwon, G. Baek, K. M. K. Swamy, M. Lee, Q.
Xu, Y. Kim, S. Kim, J. Yoon, Dyes Pigm. 2019, 171, 107679-107687.
For a recent reviews, see: a) P.-Z. Chen, L.-Y. Niu, Y.-Z. Chen, Q.-Z.
Yang, Coord. Chem. Rev. 2017, 350, 196–216; b) S. Mukherjee, P.
Thilagar, J. Mater. Chem. C 2016, 4, 2647-2662; c) C.-L. Wong, C.-T.
Poon, V. W.-W. Yam, Organomet. 2017, 36, 2661−2669; d) Z. Li, Y. Pei,
Y. Wang, Z. Lu, Y. Dai, Y. Duan, Y. Ma, H. Guo, J. Org. Chem. 2019, 84,
[
[
16]
13364−13373; e) Z. Li, Y. Dai, Z. Lu, Y. Pei, H. Chen, L. Zhang, Y. Duana,
H. Guo, Chem. Commun. 2019, 55, 13430-13433.
17] For recent works, see: a) L. Long, X. Yuan, S. Cao, Y. Han, W. Liu, Q.
Chen, Z. Han, K. Wang, ACS Omega 2019, 4, 10784−10790; b) Z. Lia,
Y. Song, Y. Dai, Y. Pei, Z. Lu, H. Guo, Opt. Mater. 2019, 95, 109235.For
cyanide ion sensor having both BF
2
and dicyanovinyl groups, see: c) Y.
Yu, T. Shu, C. Dong, Anal. Chem. Res. 2017, 12, 34-39;
7
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Entry for the Table of Contents
Insert graphic for Table of Contents here.
A triphenylamine linked difluoboron β-diketonate based sensor can detect cyanide ion in organic–aqueous media with high selectivity
-
and sensitivity. The probe embedded in cellulose test strip enables naked-eye detection of CN in a neat aqueous medium.
*Cyanide Sensing
8
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