A pyrylium-coumarin dyad as a colorimetric receptor for ratiometric detection of cyanide anions by two absorption bands in the visible region

Article abstract of DOI:10.1039/c5nj02219c

We synthesized a pyrylium-coumarin dyad (1) and used it for colorimetric detection of cyanide anions (CN^-) in aqueous media. The receptor itself exhibits a long-wavelength absorption band at 643 nm due to the strong intramolecular charge transf

Full text of DOI:10.1039/c5nj02219c

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Pyrylium–coumarin dyad as a colorimetric receptor for
ratiometric detection of cyanide anion by two absorption bands in
visible region†
Received 00th January 20xx,
Accepted 00th January 20xx
a,b
Yasuhiro Shiraishi, * Masaya Nakamura, Naoyuki Matsushita and Takayuki Hirai
a
a
a
DOI: 10.1039/x0xx00000x
−
We synthesized a pyrylium–coumarin dyad (1) and used it for colorimetric detection of cyanide anion (CN ) in aqueous
www.rsc.org/
media. The receptor itself exhibits a long-wavelength absorption band at 643 nm due to the strong intramolecular charge
–
transfer (ICT) from the diethylaminocoumarin to pyrylium moiety. Selective nucleophilic addition of CN to the pyrylium
ring triggers the ring cleavage rapidly (within 8 min). This suppresses the ICT and decreases the intensity of the 643 nm
band, along with an appearance of a new shorter-wavelength band at 472 nm assigned to the π,π* transition of the
–
diethylaminocoumarin moiety. This drastic absorption change (643 nm → 472 nm) facilitates ratiometric detection of CN
–
based on the intensities of these two absorption bands in the visible region and successfully detects CN as low as 8 µM.
9
procedure is necessary for accurate quantification.
Introduction
In contrast, ratiometric receptors, which exhibit an
–
Cyanide anion (CN ) is extremely toxic to the human body.
1
absorption band in addition to the inherent one upon
–
interaction with CN , enable quantification just by monitoring
–
Strong binding of CN to a heme unit of the cytochrome c
2
paralyzes cellular respiration and cause serious damages on
the intensities of the two absorption bands. This enables
–
accurate CN quantification without the need to consider the
3
the central nervous system. Cyanides are, however, widely
4
employed in industry for the synthesis and metallurgy,
5
effects of instruments and receptor amounts. A number of
−
ratiometric CN receptors have been proposed. Several
–
inevitably resulting in accidental release of CN into the
environment. The cyanide level in industrial waste is therefore
strictly regulated: for example, Japan’s Ministry of
2
+
2+
receptors containing metal complexes (Zn , Ni , or Cu )
2+
−
detect CN via a removal of the metal cation by the reaction
−
with CN , but produce inorganic salts as wastes. Many of
10
6
Environment sets its permissive level at 38.5 μM. Accurate
–
quantification of CN in the environmental samples is
11
−
organic receptors display poor water solubility, poor CN
1
selectivity, or a relatively long time (>10 min) for CN
2
−
therefore necessary. Several analytical methods such as
voltammetry, potentiometry, and chromatography have been
1
detection. Several receptors overcome these problems;
3
14
–
used for CN detection. These methods successfully detect
7
however, some show absorption band in the UV region (λ
<400 nm), which often overlaps with those of many
components in the environmental samples; some also exhibit
−
very low levels of CN (<0.1 μM), but need tedious sample
pretreatment or expensive instrumentation.
−
Design of colorimetric receptor for CN has attracted a
two absorption bands at very close wavelengths (ꢀ = ~50 nm),
which hinders accurate determination of the absorbance. To
−
great deal of attention because they facilitate quantitative CN
the best of our knowledge, there is only one report of
−
ratiometric CN receptor that facilitates rapid and selective
detection by simple absorption analysis on a common UV-vis
–
spectrophotometer. A number of colorimetric CN receptors
−
CN detection by well-separated two absorption bands in the
have been proposed so far. Most of the receptors show single-
wavelength absorption band, and the change in its absorbance
15
visible region. Exploiting new receptor creates many options
−
in effective ratiometric CN detection.
–
8
is used for quantification of CN . It is, however, well known
that absorbance is strongly affected by factors such as
instruments and receptor amounts, and tedious calibration
A 2,4,6-trisubstituted pyrylium moiety is one powerful
–
platform for colorimetric CN detection. As shown in Scheme
16
−
a, nucleophilic addition of CN to the carbon atom at the
1
ortho position of the pyrylium moiety leads to a drastic
conformational change via a ring opening and promotes
significant absorption change. Early reported pyrylium-based
a.
Research Center for Solar Energy Chemistry, and Division of Chemical Engineering,
Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531,
Japan. E-mail: shiraish@cheng.es.osaka-u.ac.jp.
PRESTO, JST, Saitama 332-0012, Japan.
1
6
receptors (Scheme 1b
–
a long-wavelength absorption band at 450
d), dissolved in aqueous media, show
600 nm due to the
b.
–
intramolecular charge transfer (ICT) from the substituent at
†
Electronic Supplementary Information (ESI) available: supplementary data
including Table S1, Figs. S1–S10, and Cartesian coordinates for the compounds.
See DOI: 10.1039/x0xx00000x
the para position to the pyrylium moiety. Selective
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ARTICLE
Journal Name
–
+
nucleophilic addition of CN to the pyrylium moiety leads to a tetrafluoroborate (TPP BF ) in MeCN for 3 h gave 4-methyl-
–
4
View Article Online
18
DOI: 10.1039/C5NJ02219C
decrease in these bands. They, however, scarcely show new 2,6-diphenylpyrylium tetrafluoroborate (
2
)
as brown powder
with 7-
diethylaminocoumarin-3-aldehyde in MeCN for 2 h gave
with 91% yield as dark blue solid. The purity of the products
absorption band in the visible region; therefore, they cannot with moderate yield (59%). Condensation of
–
be used for ratiometric CN detection.
2
19
1
1
13
was confirmed by H, C NMR and FAB-MS analysis (Figs. S1–
S4, ESI†).
a
0.9
0.6
0.3
0
–
–
–
–
none, F , Cl , Br , I
–
–
–
H PO , NO , AcO
2
4
3
–
–
–
ClO4 , SCN , HSO4
–
CN
–
Scheme 1. (a) Nucleophilic addition of CN to 2,4,6-trisubstituted pyrylium cation. (b–
–
d) Structures of early-reported pyrylium-based CN receptors.
300
400
500
600
700
800
λ / nm
b
0.9
The purpose of the present work is to design a pyrylium-
–
based receptor for ratiometric detection of CN . As shown in
none
Scheme 2, we synthesized a simple diethylaminocoumarin–
–
–
–
–
–
–
+ CN or
–
X = F , Cl , Br , I
1
1
0
.6
–
–
–
–
pyrylium dyad (1). The receptor dissolved in aqueous media
+ CN + X
H PO , NO3 , AcO
2 4
shows a long-wavelength absorption band at 643 nm due to
–
–
–
ClO4 , SCN , HSO4
the strong ICT from the diethylaminocoumarin to pyrylium
–
moiety. Relatively rapid nucleophilic addition of CN to
0.3
0
1
(
within 8 min) selectively triggers the cleavage of the pyrylium
ring. This suppresses ICT and creates a new short-wavelength
absorption at 472 nm assigned to * transition of the
diethylaminocoumarin moiety itself. This drastic absorption
change (
π,π
3
00
400
500
λ / nm
= 171 nm) therefore facilitates ratiometric detection Fig. 1 (a) Absorption spectra of 1 (10 μM) measured with 20 equiv. of each respective
600
700
800
ꢀ
–
–
of CN and successfully detects very low levels of CN
detection limit: 8 μM).
anions in a buffered water/MeCN mixture (1/9 v/v; Tris-HCl 10 mM, pH 9.0) at 25 °C.
–
Photographs of the solutions obtained with or without CN are also shown in the figure.
(
–
b) Absorption spectra of 1 (10 μM) measured with 20 equiv. of CN together with 20
(
–
equiv. of other each respective anions (X ). All of the measurements were performed
after stirring the solution for 10 min.
Absorption spectra of
1 (10 μM) was measured in a
buffered water/MeCN mixture (1/9 v/v; Tris-HCl 10 mM, pH
9
.0) at 25
°
1
C. As shown in Fig. 1a, the aqua blue solution
shows a distinctive absorption band at 643 nm.
containing
–
Addition of 20 equiv of each respective anions (F , Cl , Br , I ,
–
–
–
–
–
–
H PO , NO , AcO , ClO , SCN , HSO ) to the solution
–
–
–
2
4
3
4
4
followed by stirring for 10 min scarcely changes the spectrum.
–
In contrast, as shown by the red line, addition of CN leads to a
decrease in the 643 nm band, along with an appearance of
significantly blue-shifted band at 472 nm. This suggests that
1
Scheme 2 Synthesis of the receptor 1.
–
selectively reacts with CN and promotes drastic spectral
–
change. In addition, as shown in Fig. 1b, the CN -induced
spectral change is scarcely affected by the presence of other
–
anions. These data clearly suggest that 1 selectively detect CN
Results and discussion
Synthesis and absorption properties
even in the presence of these contaminating anions. It must
–
The receptor
Scheme 2, with 2,6-diphenylpyrylium tetrafluoroborate (
a starting material. Reaction of with CH MgI in diethyl ether after addition of 20 equiv. of CN . The absorption change is
for 10 h followed by reaction with tetraphenylphosphonium
1
was synthesized by the procedure depicted in also be noted that
1
rapidly detects CN . Fig. 2 shows the time-
1
)
7
3
as dependent change in the absorption spectra of measured
1
–
3
3
2
| J. Name., 2012, 00, 1-3
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ARTICLE
mostly completed within 8 min, which is much faster than that set by Japan’s Ministry of Environment. The receptor therefore
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20
10c,11a,12f,g,13,14a
–
allows sensitive CN detection in aqueous media.
DOI: 10.1039/C5NJ02219C
for early reported receptors (>10 min).
0
.9
1
5
0
5
0
12
11
10
4
72 nm
0
0
0
.9
.6
.3
0
0.6
8
ꢁM
1
0.3
8 min
6
43 nm
10
0
0
5
t / min
0
10
20
0
100
200
CN ] / ꢀM
300
–
[
3
00
400
500
λ / nm
Fig. 2 Time-dependent change in the absorption spectra of 1 (10 μM) measured with
600
700
800
–
Fig. 4 Change in absorbance ratio (A643/A472) of 1 (10 μM) with CN concentration in
a buffered water/MeCN mixture (1/9 v/v; Tris-HCl 10 mM, pH 9.0) at 25 °C.
−
2
0 equiv of CN in a buffered water/MeCN mixture (1/9 v/v; Tris-HCl 10 mM, pH 9.0) at
5 °C. The spectra obtained at 0 and 8 min are indicated by blue and red lines,
–
2
Mechanism for nucleophilic addition of CN
respectively.
–
1 with CN , three
As shown in Fig. 3, during the titration of
isosbestic points are clearly observed at 352, 427, and 540 nm,
–
respectively, suggesting that the reaction of CN with
produces a single component. To clarify the stoichiometry for
the reaction, an MeCN (10 mL) solution containing (1 mg, 1.8
mol) was stirred for 30 min, and
subjected to FAB-MS analysis. As shown in Fig. S5 (ESI ), the
1
0.9
0.6
0.3
0
1
–
ꢀ
mol) and CN (0.48 mg, 1.8 ꢀ
†
–
–
solution shows a peak at m/z 501.2, assigned to [1 + CN – BF
4
+
H ] species, suggesting that
+
–
reacts with CN in a 1:1
+
1
stoichiometry.
300
400
500
600
700
800
λ / nm
–
Scheme 3 Proposed mechanism for nucleophilic addition of CN to 1.
0
10 12 14 16 18 20 equiv
–
As shown in Scheme 3, the reaction of CN with
1 occurs
–
–
Fig. 3 Result of absorption titration of
1
(
1
0 μM) with CN in a buffered water/MeCN via the nucleophilic addition of CN to the ortho position of the
mixture (1/9 v/v; Tris-HCl 10 mM, pH 9.0) at 25 °C. All of the measurements were
pyrylium ring of 1, as is the case for related pyrylium-based
16
receptors (Scheme 1a), leading to the formation of the ring-
performed after stirring the solution for 10 min. Photographs of the solutions obtained
–
with different amount of C
N
(equiv.) are shown at the bottom.
–
1
opened
1
–
CN species. To clarify this, H NMR analysis was
(Scheme 2) as a model
It is noted that shows properties
; as shown in Fig. S6 (ESI ), absorption
with CN leads to a decrease in a 401 nm band
and an increase in a 340 nm band, with an isosbestic point at
64 nm. FAB-MS analysis of the product obtained by the
–
performed with the compound
3
Ratiometric sensing of CN
21
compound in place of
similar to those of
titration of
1
.
3
–
1 with CN .
Fig. 3 shows the results of absorption titration of
–
Stepwise addition of CN to the solution leads to a decrease in
the 643 nm band, along with an increase in the 472 nm band.
1
†
–
3
These clearly-separated two bands of 1 in the visible region
–
facilitate ratiometric detection of CN . Fig. 4 shows the change
3
–
reaction of
assigned to [
indicative of 1:1 interaction of
3 with 1 equiv of CN shows a peak at m/z 260.1,
–
–
+ +
in the ratio of the absorbance for the two bands (A 43/A472),
6
3 + CN – BF + H ] species (Fig. S7, ESI†),
4
–
when plotted as a function of CN concentration. A linear
–
with CN , as is the case for 1.
3
–
relationship is observed in the range of 8–200 μM CN (R =
2
1
–
–CN species
Fig. 5 shows the H NMR charts of
3
and the
3
–
.998). This indicates that 1 facilitates accurate CN sensing in
–
–CN were assigned
0
in CDCl , where the chemical shifts of
3
3
–
this range. The detection limit (8 μM) is below the maximum
permissive level of cyanide in the industrial effluents (38.5 μM),
based on the 2D COSY spectra (Fig. S8, ESI
to
†
leads to significant upfield shift of the pyrylium protons
). Addition of CN
3
a
H , H ), while the phenyl ring protons (H , H , H ) scarcely shift.
b
c
d
e
(
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ARTICLE
The triplet H proton (9.24 ppm) changes to double doublet
Journal Name
a
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DOI: 10.1039/C5NJ02219C
b
7.92 ppm), and doublet H protons (8.64 ppm) separate into
(
two doublets (7.51 and 7.33 ppm). This suggests that, as
–
shown in Fig. 5 (top), nucleophilic addition of CN to the ortho
position of the pyrylium ring leads to ring cleavage. In addition,
C3,C5
a
–
coupling constant of the double doublet H protons of
5.1 and 11.4 Hz. It is well known that trans-coupling of
protons in diene derivatives usually exhibits a large coupling
3–CN is
a
1
C2,C6
C4
2
2
constant (12
–18 Hz). The large coupling constant (15.1 Hz) is
therefore due to the trans-coupling between H and H
a
b2
–
3–CN exists in
b
protons. This suggests that the diene moiety of
a trans form (Fig. 5, top). It must also be noted that, as shown
–
in Fig. S9 (ESI†), IR analysis of 3–CN on KBr disk shows a
characteristic band at 1653 cm , assigned to C=O stretching
–
1
C6
C4,C5 C3 C2–C≡N
1
vibration. These H NMR and IR data support the formation of
2
00
180
160
140
120
–
–CN species, as shown in Fig. 5 (top).
δ / ppm
Fig. 6 C NMR chart of (a) 3 (10 mM, 100 MHz, 30 °C, CD
ring-opened
3
13
–
3
CN) and (b) 3−CN species (10
mM, 100 MHz, 30 °C, CDCl ). The respective chemical shifts were assigned based on ab
3
3
initio calculation (B3LYP/6-311+G(2d,p)) using PCM with MeCN and CHCl , respectively.
⃰
Mechanism for ratiometric absorption response
The significant blue shift of the absorption spectrum of
1
–
upon addition of CN is due to the localization of π-electrons
on the diethylaminocoumarin moiety. This is confirmed by ab
initio calculation based on the time-dependent density
Hd
He
a
Hb
Hc
Ha
23
functional theory (TD-DFT) performed within the Gaussian 03
24
program using the B3LYP/6-31G* basis set. As summarized in
Table S1 (ESI ), singlet electronic transition of mainly
consists of HOMO → LUMO (S → S ) transition. Its transition
†
1
Hb1
0
1
energy is determined to be 2.14 eV (580 nm), which is close to
the observed λmax (643 nm) of the absorption spectrum of
Fig. 3). As shown in Fig. 7 (left), π-electrons of HOMO of are
Hb2
1
(
1
b
⃰
localized on the diethylaminocoumarin moiety, while those of
LUMO are delocalized over the entire molecule. The total
change in dipole moment for the S → S transition is relatively
0
1
9
8.5
8
7.5
large (9.6 Debye). This indicates that the 643 nm absorption
(Fig. 3) is due to the intramolecular charge transfer
(ICT) from the diethylaminocoumarin to pyrylium moiety.
As shown in Table S1 (ESI ), singlet electronic transition of
–CN species is mainly contributed by HOMO → LUMO+1 (S
) transition. Its energy is determined to be 3.14 eV (395
creates a new peak at higher magnetic field (115.64 nm), which is close to λmax of the absorption spectrum of the
δ / ppm
1
–
Fig. 5 H NMR chart (400 MHz, 30 °C
,
3
CDCl )
for (a) 3 (2 mM) and (b) 3−CN species band of
1
25
(
3
10 mM). The peaks denoted by asterisks are assigned to the residual CHCl .
†
1
3
–
–
C NMR analysis of the
3
–CN species further confirms the
1
0
reaction mechanism (Fig. 5, top). As shown in Fig. 6b, addition → S
4
–
of CN to
3
–
ppm), assigned to the –C
≡
N group added to
3
. As shown in Fig.
1–CN species (472 nm, Fig. 3). As shown in Fig. 7 (right), π-
–
6
a, the carbon atoms at the ortho position of the pyrylium ring electrons of both HOMO and LUMO+1 for
1
–CN are localized
on the diethylaminocoumarin moiety. The total change in the
→ S transition is very small (1.2
–
of
3 (C2 and C6) appear at 173.3 ppm. Addition of CN
separates it into two peaks at 121.5 and 189.7 ppm, dipole moment for the S
0
4
respectively. The significant downfield shift of the C6 carbon is Debye). This indicates that the 472 nm absorption band is due
due to the formation of –C=O group via the ring-opening to the π,π* transition of the diethylaminocoumarin moiety,
1
reaction. The results agree with the H NMR (Fig. 5) and IR and the transition has almost no ICT character. The
–
data (Fig. S9, ESI
compound
proposed in Scheme 3, nucleophilic addition of CN to the to pyrylium moiety and leads to localization of the electrons on
ortho position of the pyrylium ring of
produces ring-opened the diethylaminocoumarin moiety. The disappearance of the
–CN species. This drastic conformational change therefore ICT character therefore facilitates significant blue shift of the
†
). The above findings obtained with the nucleophilic addition of CN to
1
promotes cleavage of the
3
as a model compound clearly suggest that, as pyrylium ring. This suppresses ICT from diethylaminocoumarin
–
1
–
1
leads to a significant change in absorption spectra (Fig. 3).
absorption spectra (643 nm
–
ratiometric detection of CN .
→
472 nm) and, hence, facilitates
4
| J. Name., 2012, 00, 1-3
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View Article Online
DOI: 10.1039/C5NJ02219C
LUMO+1
ELUMO+1= –1.77 eV
ELUMO= –3.27 eV
LUMO
3.45 eV
2.31 eV
HOMO
HOMO
EHOMO= –5.58 eV
EHOMO= –5.22 eV
1
1
–CN–
–
Fig. 7 Energy diagrams for main orbitals of (left) 1 and (right) 1–CN species, calculated at the DFT level (B3LYP/6-31G*) using PCM with MeCN as a solvent. Gray, white, blue, and
red atoms indicate C, H, N, and O atoms, respectively. Green and deep red parts on the molecular orbitals refer to the different phases of molecular wave functions (isovalue: 0.02
a.u.).
Compound 2: This was synthesized according to literature
1
8
Conclusions
procedure.
3 (186 mg, 0.55 mmol) was stirred in diethyl
ether (10 mL) containing CH MgI (1.66 g, 10 mmol) at 25 °C for
3
We found that a pyrylium–coumarin dyad (1) behaves as a
–
10 h under N . The solution was washed with saturated NH Cl
2
4
colorimetric receptor for ratiometric detection of CN in
aqueous media. The receptor itself shows a long-wavelength-
absorption band (643 nm) due to the ICT from the coumarin to
solution (10 mL
×
by evaporation. The resultant and TPP BF (280 mg, 1.1
2) and water (10 mL
×
2), and concentrated
+
–
4
–
mmol) were stirred in MeCN (4 mL) at 25 °C for 3 h. The
resultant was concentrated by evaporation and dissolved in a
small amount of acetone (1 mL). The precipitate formed by the
pyrylium moiety. Nucleophilic addition of CN to the receptor
triggers selective cleavage of the pyrylium ring. This
suppresses ICT and creates new shorter-wavelength-
addition of n-hexane (3 mL) was recovered by filtration,
1
as brown powder (103.8 mg, 59 %). H-NMR
absorption band (472 nm) due to the
coumarin moiety. This facilitates selective, sensitive (detection
limit: 8 M), and rapid (assay time: 8 min) ratiometric
π,π* transition of the
affording
2
(DMSO-d ) δ (ppm) : 8.84 (2H, s), 8.43 (4H, d, J = 7.8 Hz), 7.86-
6
ꢁ
–
7.78 (6H, m), 2.84 (3H, s).
Compound
diethylaminocoumarin-3-aldehyde (28 mg, 0.11 mmol) were
dissolved in MeCN (7 mL) and stirred at 25 C for 2 h. The color
detection of CN by two absorption bands in the visible
wavelength region. Application of the present receptor to real
sample sensing is still difficult because it involves several
problems that must be addressed: it needs organic solvents
due to the low solubility in pure water; and it shows relatively
high detection limit. Nevertheless, the basic concept presented
here based on the change in two absorption bands via the
1
:
2
(30 mg, 0.09 mmol) and 7-
19
°
of the solution changes immediately to dark green. The
solution was concentrated by evaporation, and EtOH (10 mL)
was added to the resultant. The solids formed were recovered
–
by filtration and washed with thoroughly with EtOH (20 mL),
1
as dark blue solid (40.9 mg, 91 %). H-NMR (DMSO-
nucleophilic addition of CN to the pyrylium moiety may
–
contribute to the design of more efficient CN receptors.
affording
1
d6) δ (ppm) : 8.69 (2H, s), 8.50 (1H, d, J = 15.6 Hz), 8.36 (4H, d, J
7.3 Hz), 8.24 (1H, s), 7.86 (1H, d, J = 15.1 Hz), 7.79-7.71 (6H,
m), 7.60 (1H, d, J = 9.2 Hz), 6.86 (1H, d, J = 8.2 Hz), 6.63 (1H, s),
=
Experimental
13
3
.54 (4H, d, J = 6.9 Hz), 1.18 (6H, t, J = 6.9 Hz). C NMR (100
General
MHz, DMSO-d , TMS) δ (ppm): 166.40, 162.30, 158.75, 157.26,
6
+
All of the anions were used as n-Bu N salts. All of the reagents 153.69, 149.39, 146.89, 134.02, 132.15, 129.63, 129.28, 127.65,
4
used were purchased from Wako, Aldrich, and Tokyo Kasei, 121.93, 113.24, 113.03, 111.04, 109.55, 96.38, 44.78, 12.41.
+
− +
and used without further purification. Water was purified by FAB-MS: m/z: calcd for C H NO ([
1 – BF ] ) 474.6; found:
4
3
2
28
3
+
3
− +
the Milli-Q system. Absorption spectra were measured on an 474.2; HR-MS (FAB+): m/z: calcd for C H NO ([
1 – BF ] ):
4
32
28
UV-visible photodiode-array spectrophotometer (Shimadzu; 474.2064; found: 474.2069.
–
+
–
Multispec-1500) equipped with a temperature controller
Shimadzu; S-1700) using a 10 mm path length quartz cell mg, 0.34 mmol) were dissolved in MeCN (4 mL) and stirred at
3–CN species: 3 (112 mg, 0.34 mmol) and n-Bu N CN (92
4
(
1
13
under aerated conditions. H and C NMR charts were 25
°C for 5 h. The solution was concentrated by evaporation.
obtained by a JEOL JNM-ECS400 spectrometer. FAB-MS The resultant (204 mg) was adsorbed onto a silica gel column
analysis was performed on a JEOL JMS 700 Mass Spectrometer. (100 g) and eluted using a mixture of toluene/CH Cl /n-hexane
2
2
Compound
procedure.
3
7
was synthesized according to the literature (1/1/3 v/v/v, 600 mL), (3/2/3 v/v/v, 600 mL), and then (0/1/0
v/v/v, 600 mL). Condensation of the final eluent afforded
1
3
–
–
CN as yellow solid (3.2 mg, 4 %). H-NMR (CDCl ) δ: 7.98 (2H,
1
3
Synthesis
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
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Page 6 of 8
ARTICLE
d, J = 5.3 Hz), 7.92 (1H, dd, J = 15.1, 11.4 Hz), 7.70-7.68 (2H, m),
Journal Name
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0 (a) K. P. Divya, S. Sreejith, B. Balakrishna, P. JaVyieawmArutirctlehOyn,linPe.
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mun., 2010, 46, 6069–
7
7
.61 (1H, t, J = 7.6 Hz), 7.51 (2H, t, J = 7.6 Hz), 7.47-7.43 (4H, m),
13
.33 (1H, d, J = 15.1 Hz). C NMR (100 MHz, CDCl , TMS) δ
3
(
(ppm): 189.66, 138.55, 138.20, 137.41, 133.35, 132.45, 132.24,
Chem., 2014, 12, 3991–4001; (d) N. Khairnar, K. Tayade, S.
Bothra, S. K. Sahoo, J. Singh, N. Singh, R. Bendre and A.
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and W. Jang, Chem. Commun., 2015, 51, 7486–7488.
1 (a) L. Yuan, W. Lin, Y. Yang, J. Song and J. Wang, Org. Lett.,
011, 13, 3730–3733; (b) X. Cheng, Y. Zhou, J. Qin and Z. Li,
ACS Appl. Mater. Interfaces, 2012, , 2133−2138; (c) L. Yang,
X. Li, J. Yang, Y. Qu and J. Hua, ACS Appl. Mater. Interfaces,
013, , 1317−1326; (d) S. Madhu, S. K. Basu, S. Jadhav and
1
30.62, 129.30, 128.82, 128.58, 126.34, 121.53, 115.64. FAB-
+
−
–
+ +
MS: m/z: calcd for C H NO ([3 – BF + CN + H ] ) 260.3;
4
18
14
+
found: 260.1; HR-MS (FAB+): m/z: calcd for C H NO ([3 –
1
8 14
−
–
BF + CN + H ] ): 260.1070; found: 260.1075.
+ +
4
Calculation details
1
2
Ab initio calculations were performed with tight convergence
24
4
criteria at the DFT level with the Gaussian 03 package, using
the B3LYP/6-31G* basis set for all atoms. The excitation
energies and oscillator strengths of the compounds were
2
5
M. Ravikanth, Analyst, 2013, 138, 299–306; (e) S. Sharma, M.
S. Hundal and G. Hundal, Org. Biomol. Chem., 2013, 11, 654–
23
calculated by TD-DFT at the same level of optimization.
Calculated NMR charts were obtained using the DFT
6
61; (f) X. Zhou, W. Mu, X. Lv and D. Liu, RSC Adv., 2013,
22150–22154; (g) B. H. Shankar, D. T. Jayaram and D.
Ramaiah, Chem. Asian J., 2014, , 1636–1642; (h) M. Zhou, J.
3,
26
GIAO/B3LYP method with the 6-311+G(2d,p) basis set, using
9
the polarizable continuum model (PCM) with MeCN or CHCl
3
Chen, C. Liu, H. Fu, N. Zheng, C. Zhang, Y. Chen and J. Cheng,
Chem. Commun., 2014, 50, 14748–14751; 11 (i) R. Kumar, N.
Chaudhri and M. Sankar, Dalton Trans., 2015, 44, 9149–9157.
2 (a) N. Kumari, S. Jha and S. Bhattacharya, J. Org. Chem., 2011,
27
as a solvent. Cartesian coordinates are summarized in the
end of ESI
†
.
1
7
6
, 8215–8222; (b) X. Lv, J. Liu, Y. Liu, Y. Zhao, M. Chen, P.
Wang and W. Guo, Org. Biomol. Chem., 2011, , 4954–4958;
c) Z. Yang, Z. Liu, Y. Chen, X. Wang, W. He and Y. Lud, Org.
9
Acknowledgements
(
This work was supported by the Grant-in Aid for Scientific
Research (No. 15K06556) from the Ministry of Education,
Culture, Sports, Science and Technology, Japan (MEXT) and the
Precursory Research for Embryonic Science and Technology
Biomol. Chem., 2012, 10, 5073–5076; (d) X. Cheng, R. Tang, H.
Jia, J. Feng, J. Qin and Z. Li, ACS Appl. Mater. Interfaces, 2012,
4
, 4387−4392; (e) Q. Lin, X. Liu, T. Wei and Y. Zhang, Chem.
Asian J., 2013, , 3015–3021; (f) N. Kumari, S. Jha and S.
Bhattacharya, Chem. Asian J., 2014, , 830–837; (g) R. K.
Konidena and K. R. J. Thomas, RSC Adv., 2014, , 22902–
2910; (h) M. Peng, Y. Guo, X. Yang, F. Suzenet, J. Li, C. Li and
8
9
(PRESTO) from Japan Science and Technology Agency (JST).
4
2
Y. Duan, RSC Adv., 2014, 4, 19077–19085; (i) A. B. Davis, R. E.
Lambert, F. R. Fronczek, P. J. Cragg and K. J. Wallace, New J.
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New Journal of Chemistry
Journal Name
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8 L. E. Santos-Figueroa, C. Gimenez, A. Agostini, E. Aznar, M. D.
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0 The compound
1
cannot be used for fluorometric detection
of CN . Fig. S10 (ESI ) shows the fluorescence spectra (λex
27 nm and 540 nm) of (10 M) measured with 50 equiv of
CN in a buffered water/MeCN mixture (1/9 v/v; pH 9.0) at
5 °C. Photoexcitation at λex = 540 nm, shows almost no
–
†
=
4
1
ꢁ
–
2
–
fluorescence without or with CN . In contrast, photoexcitation
at λex = 427 nm shows CN -induced fluorescence increase, but
–
the increase is only 4.4 fold. This is insufficient for fluorometric
sensing of CN .
–
1
–
2
1
H NMR analysis of the 1–CN species was unsuccessful even
though several experiments (i iii) were performed: (i) A
CD CN solution containing and 1 equiv. of CN was stirred
–
–
1
3
for 30 min and subjected to analysis. The obtained chart
shows broad (unresolved) chemical sifts in the range of 5–10
ppm probably due to the presence of large amount of
impurities. (ii) An MeCN solution containing
1 and 1 equiv. of
–
CN was stirred for 30 min. The resultant was concentrated
by evaporation. Recrystallization of the obtained black oil
was unsuccessful in any solvents such as alkanes, aromatics,
alcohols, and ethers. (iii) Purification of the black oil using
column chromatography with silica gel or aluminium oxide is
also unsuccessful: any solid cannot be obtained. Based on
1
for H NMR
the above, we decided to use the compound
analysis in place of
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New Journal of Chemistry
Page 8 of 8
View Article Online
DOI: 10.1039/C5NJ02219C
Manuscript title: Pyrylium–coumarin dyad as a colorimetric receptor for ratiometric
detection of cyanide anion by two absorption bands in visible region
Authors: Yasuhiro Shiraishi,* Masaya Nakamura, Naoyuki Matsushita and Takayuki Hirai
Graphical Abstract
6
43 nm
472 nm
A pyrylium–coumarin dyad behaves as a colorimetric receptor for ratiometric detection of
cyanide anion in aqueous media by two absorption bands in visible wavelength region.