A turn-on fluorescent BOPHY probe for Cu2+ ion detection

Article abstract of DOI:10.1039/c7nj03911e

A new fluorine-boron compound BOPHY-PTZ was designed and synthesized. The fluorescent dye was used as a highly sensitive probe for Cu²⁺ ion detection. The mechanism of detection involved Cu²⁺ ion oxidation of the phenothiazine (PTZ) moiety and blocked the intramolecular charge transfer (ICT) process from the electron-donating PTZ moiety to the electron-accepting BOPHY moiety. BOPHY-PTZ showed a weak fluorescence in solution. However, it displayed a strong fluorescence signal enhancement upon the addition of Cu²⁺ ions, and 1.0 nM concentration of Cu²⁺ can be clearly detected. The assay is simple, sensitive and convenient, and it exhibits excellent selectivity for Cu²⁺ ions over the other metal ions. The BOPHY-PTZ probe could be used for Cu²⁺ ion detection in practical samples and for environmental monitoring related applications.

Full text of DOI:10.1039/c7nj03911e

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PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
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ARTICLE
2
+
A turn-on fluorescence BOPHY probe for Cu ions detection
ac
a
a
ab
ab
a
ab
Chunhua He , Huipeng Zhou *, Na Yang , Niu Niu , Ejaz Hussain , Yongxin Li , Cong Yu *
Received 00th January 20xx,
Accepted 00th January 20xx
A new fluorine boron compound BOPHY-PTZ was designed and synthesized. The fluorescence dye was used as a highly
2
+
2+
sensitive probe for Cu ions detection. The mechanism of detection involved Cu ions oxidization of the phenothiazine
PTZ) moiety and blocked the intramolecular charge transfer (ICT) process from the electron-donating PTZ moiety to the
electron-accepting BOPHY moiety. BOPHY-PTZ showed weak fluorescence in solution. However, it displayed strong
DOI: 10.1039/x0xx00000x
(
www.rsc.org/
2+
2+
fluorescence signal enhancement upon the addition of Cu ions, and 1.0 nM concentration of Cu can be clearly detected.
2
+
The assay is simple, sensitive and convenient, and it shows excellent selectivity for Cu ions over the other metal ions. The
2+
BOPHY-PTZ probe could be used for Cu ions detection in actual samples, and for environment monitoring related
applications.
Introduction
compelling one because of its high fluorescence quantum yield,
high molar absorption coefficient, excellent thermal stability, and
Selective and sensitive detection of various heavy metal ions has
become more and more significant in the areas of bioanalysis and
1
4-15
easy modification properties.
It has been widely used for the
1
development of various fluorescence sensors. Ziegler et al. reported
a new fluorine boron compound based on pyrrole-boron difluoride,
namelybis(difluoroboron)-1,2-bis[(1H-pyrrol-2-yl)methylene]hydraz-
environmental monitoring. Among the essential heavy metal ions,
copper is ranked the third after iron and zinc in the human body. It
is widely distributed in human blood and tissues, and plays a pivotal
1
6
2
-3
ine(BOPHY) in 2014. BOPHY has many outstanding photophysical
properties comparable to BODIPY, such as high fluorescence
quantum yield, high extinction coefficient, and high stability. In
addition, it has more available reactions sites for the introduction of
various functional groups, which could be used to generate
role in many cellular processes, e.g. as enzyme cofactor. However,
2
+
when the concentration of Cu exceeds the required level for the
2
+
cellular process, Cu can be toxic and cause diseases such as
4
5
Alzheimer's disease, kidney damage, Meknes and Wilson’s
6
2+
disease. In addition, Cu is also a prominent environmental
1
7-18
7
fluorescence probes of various properties.
However, there are
pollutant due to the lack of effective management of wastewater.
2
+
few reports on the synthesis and application of BOPHY derivatives.
To our knowledge, up to date only two BOPHY derivatives were
reported as biosensors. One is for the detection of assay solution
pH, and the other is for the detection of copper ions from to our
The establishment of effective Cu detection methodology has
attracted widespread attention over the past decade, and a variety
2
+
of fluorescence Cu probes that exhibit either fluorescence ‘on-off’
or ‘off-on’ signaling mode have been reported based on various
mechanisms such as intramolecular charge transfer (ICT),
fluorescence resonance energy transfer (FRET), photo-induced
electron transfer (PET), metal-ligand charge transfer (MLCT),
1
9-20
group.
It is therefore of considerable interest to design and
synthesize BOPHY based highly specific and sensitive fluorescence
probe for bioanalysis and bioimaging applications.
8
-13
Herein, we designed and synthesized a novel D-π-A type
twisted intramolecular charge transfer (TICT), etc..
And novel
2
+
fluorescence BOPHY derivative (BOPHY-PTZ). BOPHY-PTZ consists
of two parts: an electron acceptor tetramethylsubstituted BOPHY
signaling element, and a strong electron donor phenothiazine
Cu selective probes are constantly emerging in the literature, but
the design and synthesis of highly sensitive and selective
2
+
fluorescence biosensors for Cu are still a challenge.
(
Figure 1). The dye was prepared by Knoevenagel condensation
reaction between tetramethylsubstituted BOPHY and 10-methyl-
0H-phenothiazine-3-carbaldehyde. BOPHY-PTZ shows very weak
Among the fluorescence probes reported, boron dipyrromethene
(
BODIPY), as one of the fluorine boron compounds, is a very
1
fluorescence emission in acetonitrile solution because the
fluorophore can be quenched by the effective electron transfer
1
9, 21-23
from PTZ unit to BOPHY unit.
turn on fluorescence upon the addition of Cu ions. And a highly
However, it shows significant
2
+
2
+
sensitive fluorescence probe for the detection of Cu is developed.
A minimum detection concentration of 1.0 nM is observed. This
assay also exhibits excellent selectivity. This work will promote the
further development of various fluorine boron fluorescence probes
for analysis, detection and imaging.
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2
+
Cu ions (0 - 15 µM) and BOPHY-PTZ (1 µM) were mixed,
equilibrated at 20 ºC for 5 min, and the emission spectra were
recorded (total sample volume: 399 µL acetonitrile plus 1 µL water).
Synthesis of BOPHY-PTZ
The synthetic route for the phenothiazine-based BOPHY dye
(
BOPHY-PTZ) is shown in Scheme 1. The hydrazine derivative (1)
and the tetramethylsubstituted BOPHY (2) were prepared using our
1
6
Figure 1. The schematic illustration of fluorescence “turn-on” method by BOPHY-
established method. And the 10-methyl-10H-phenothiazine-3-
2
+
PTZ probe for selective detection of Cu ions. Inset: Photograph of BOPHY-PTZ
24
carbaldehyde (4) was synthesized following the reported method.
2
+
2+
under UV lamp (365 nm), (1) without Cu , (2) with Cu .
The BOPHY-PTZ dye was synthesized via
a Knoevenagel
condensation reaction catalyzed by piperidine using compounds 2
and 4 as the starting materials.
Experimental section
Briefly, piperidine (2 mL) and toluene-4-sulfonic acid (100 mg)
were added to the reaction mixture of compound 2 (100 mg, 0.30
mmol) and compound 4 (145 mg, 0.60 mmol) in 20 mL of dry
Materials and measurements
All metal salts are in the form of nitrate salts, except FeCl
3
•6H
were
was bought from
, and Cd(NO were
obtained from Xilong Science Work. KNO Mn(NO
Ni(NO •6H O, Hg(NO and Mg(NO were purchased from
2
O.
Cu(NO
purchased from Beijing Chemical Works. Ba(NO
Shanghai Hanhong Scientific Co., Ltd. Pb(NO
3
)
2
•3H
2
O, Zn(NO
3
)
2
•6H
2
O, FeCl
3
•6H
2
O, and LiNO
3
o
toluene at 0 C. The reaction mixture was stirred for 15 min at room
3 2
)
temperature, and refluxed for 24 h. TLC was used to monitor the
reaction process. The reaction mixture was cooled to room
temperature, and quenched with 100 mL of water. The product was
extracted by dichloromethane (3 × 50 mL). The organic phase was
collected and washed with NaCl aqueous solution. After drying over
3
)
2
3 2
)
3
,
3 2
) ,
3
)
2
2
3
)
2
3 2
)
Sinopharm Chemical Reagent Co., Ltd. AgNO3 was bought from
Shanghai Chemical Reagent. Spectral grade acetonitrile, piperidine,
hydrazine hydrate, toluene-p-sulfonic acid, 2-formyl(3,5-dimethyl
4
anhydrous MgSO , solvent was removed through rotary evaporator.
The crude product was purified by column chromatography on silica
gel using a mixture of petroleum ether / ethyl acetate (6 / 1) as
pyrrole), ethyldiisopropylamine (DIPEA) and BF •OEt2 were
3
purchased from Beijing Chemical Reagent (Beijing, China). Ultrapure
1
eluent, to give a deep red solid with a yield of 40 %. H-NMR (500
deionized water was processed using
Millipore, Billerica, MA, USA).
UV-vis absorption spectra were recorded on
Biospectrophotometer (Varian Inc., CA, USA). Fluorescence
emission spectra were collected by Fluoromax-4
a Milli-Q A10 system
MHz, CDCl
3
): δ 7.96 (s, 1H), 7.91 (s, 1H), 7.36-7.32 (m, 2H), 7.24 (s,
(
1
1
2
H), 7.20-7.13 (m, 3H), 6.95 (t, J = 7.5 Hz, 1H), 6.83 (d, J = 7.9 Hz,
a
Cary 50
H), 6.78 (d, J = 8.9 Hz, 1H), 6.71 (s, 1H), 6.19 (s, 1H), 3.40 (s, 3H),
.50 (s, 3H), 2.36 (s, 3H), 2.34 (s, 3H) (Figure S1, Supporting
a
13
Information). C-NMR (125 MHz, CDCl ): δ 159.06, 158.66, 151.13,
3
spectrofluorometer (Horiba Jobin Yvon Inc., USA) with slits for
excitation and emission both of 5 nm. BOPHY-PTZ solutions were
excited at 490 nm. Quartz cuvettes with 10 mm path length and 2
mm window width were used for UV-vis and fluorescence
1
1
1
46.53, 144.97, 140.83, 140.48, 135.46, 134.02, 133.45, 130.67,
27.53, 127.20, 127.14, 125.50, 123.89, 122.83, 122.78, 118.51,
15.86, 114.71, 114.55, 114.23, 114.06, 35.45, 29.66, 14.10, 11.14
-1
(
Figure S2). IR (KBr, cm ): 2952, 2927, 2852, 1592, 1528, 1464, 1292,
1
13
measurements. H-NMR and C-NMR spectra were obtained in
CDCl3 using BRUKER spectrometer at 500 MHz and 125 MHz,
respectively. Mass spectra were acquired with a MALDI-TOF-MS (AB
sciex 5800 MALDI-TOF). FT-IR spectra were measured using a
VERTEX 70 spectrophotometer (Bruker, Germany).
9
5
59, 854, 752 (Figure S3). MS (MALDI-TOF), m/z: cal: 561.2, found:
61.2 (Figure S4).
Cyclic Voltammetry
Cyclic voltammetry (CV) was performed at room temperature using
the three electrode system. Ag/AgCl and SCE used as the reference
electrode,
electrode, and Pt wire was employed as the working electrode. 100
µM (TBAPF ) and 0.1 M K SO were used as the supporting
a glassy carbon electrode served as the working
6
2
4
electrolyte. Measurement was completed in acetonitrile or water
using CHI 640B electrochemical working station at a scan rate of 50
-
1
mV·s .
Assay procedures
The stock solution of the fluorescence probe was prepared in
o
acetonitrile and stored at 4 C before use. Various concentrations of Scheme 1. Synthesis of the BOPHY-PTZ probe.
2
| J. Name., 2012, 00, 1-3
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Figure 2. Changes in UV-vis absorption (a) and fluorescence emission (b) spectra
2
+
of BOPHY-PTZ (1 µM) upon the addition of different concentrations of Cu ions
0-2 µM).
Results and Discussion
(
A
new donor-π-acceptor type fluorescent BOPHY derivative
(
BOPHY-PTZ) was designed and synthesized, with a phenothiazine
Moreover, the HOMO and LUMO molecular orbitals of BOPHY-
2
4
functional group at the α-position of the pyrrole ring. The PTZ and the oxidation products BOPHY-PTZO were depicted using
1
13
structure and purity of BOPHY-PTZ was assessed by H-NMR, C- density functional theory (DFT) at B3LYP/6-31G* (Figure 3), and the
NMR, IR and mass spectrometry. The IR spectrum of compound corresponding data are listed in Table S2. The electron density of
BOPHY-PTZ shows a vibration absorption band at around 960 cm-1 HOMO of the BOPHY probe is mainly located at the phenothiazine
2
5
arising from the wagging vibration of the trans-double bond (C=C).
moiety, and the electron density of LUMO is primarily located at the
1
Furthermore, H-NMR spectrum of BOPHY-PTZ also confirms that BOPHY acceptor moiety and the nearby double bond (–CH=CH–).
the ethenyl group is in the trans-conformation because of the The strong electron density relocation between HOMO and LUMO
1
9
absence of the 6.5 ppm signal assigned to the protons in cis-double strongly supports a charge transfer transition (CT) process. Upon
2
6
bond (CH=CH) (Figure S1).
We investigated the UV-vis absorption and fluorescence emission promoted to the LUMO, which enables ICT from the donor (PTZ unit)
spectra of BOPHY-PTZ, compound 2, and compound in to the acceptor BOPHY unit, causing fluorescence quenching.
excitation of the BOPHY fluorophore, an electron of the HOMO is
3
acetonitrile (Figure S5), and the corresponding photophysical data However, upon the oxidation of the BOPHY-PTZ, the electron
are listed in Table S1. Three separate absorption bands of BOPHY- density of HOMO of the oxidation product BOPHY-PTZO is evenly
PTZ at ca. 255, 310 and 530 nm were observed as depicted in Figure. distributed throughout the whole molecular structure suggesting
S5. Compared with compound 2 and compound 3, the red-shifted that the ICT is no longer possible, and the fluorescence intensity of
5
35 nm band of BOPHY-PTZ was attributed to the intramolecular the probes was enhanced. The oxidation of BOPHY-PTZ resulted in
charge transfer (ICT) between the electron donor PTZ unit and the a remarkable UV-vis absorption blue-shifted. It is due to the
2
3,27
electron acceptor BOPHY unit.
In acetonitrile, fluorescence increase in the HOMO-LUMO band gap (2.72 eV) observed for
emission of the BOPHY moiety of BOPHY-PTZ was effectively BOPHY-PTZO relative to that (2.52 eV) of BOPHY-PTZ by frontier
quenched. As a result, the fluorescence quantum yield of BOPHY- molecular orbitals calculations (Table S2.).
PTZ was only 0.002. However, compound 2 in acetonitrile was
highly emissive; the emission quantum yield reached 0.94.
As Figure 2 shows, BOPHY-PTZ exhibited a maximum absorption
2
+
band at 530 nm in acetonitrile. Upon the addition of Cu , the
absorbance band intensity progressively decreased, and at the
same time, a new absorption band at 465 nm appeared. The
absorption band was blue-shifted by about 80 nm. In addition,
BOPHY-PTZ showed a weak fluorescence emission due to the ICT
effect in assay solution, the emission enhanced dramatically upon
2
+
the addition of Cu ions. We suggest that the significant UV-vis
absorption and fluorescence emission changes of BOPHY-PTZ were
2
+
a result of oxidization of the phenothiazine moiety by Cu ions to
produce phenothiazine-5-oxide (PTZO), which was incapable of
quenching BOPHY fluorescence because of the blockage of the ICT
19,21
process from the electron-rich PTZ unit to the BOPHY unit.
2
+
When the probe BOPHY-PTZ was mixed with the Cu ions in assay Figure 3. Frontier orbitals (HOMO and LUMO) of BOPHY-PTZ and BOPHY-PTZO.
solution, the mass spectrum clearly showed a peak of BOPHY-PTZO
Cyclic voltammetry (CV) was employed to evaluate the redox
at 577.2, the oxidized form of BOPHY-PTZ (Fig. S6, MALDI-TOF). The
properties of BOPHY-PTZ. The CV voltammogram in the acetonitrile
result clearly indicates that the PTZ functional group was oxidized to
and water are shown in Figure S7, and the electrochemistry data
PTZO.
are listed in Table S2. The value of CV measurement is consistent
with the calculated energy level of the HOMO of BOPHY-PTZ. The
results show that the first oxidation potential (Eox) corresponding to
the highest occupied molecular orbital (HOMO) of BOPHY-PTZ (0.90
V vs NHE) is sufficiently more negative than the redox potential of
2
+
+
the Cu /Cu pair (1.19 V vs NHE) in acetonitrile. The electron
2
+
transfer reaction between the PTZ moiety and Cu ions can be
2
+
described with the following equation: BOPHY-PTZ + 2Cu
→
2
+
+ 28
BOPHY-PTZ + 2Cu . The change in free energy value (∆G) of the
electron transfer process is -0.29 eV (Table S2), demonstrating that
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2
+
the reaction between the PTZ unit and Cu is thermodynamically
favorable. However, the value of ∆G is 0.68 eV in water suggesting
that the electron transfer reaction is not thermodynamically
allowed.
2
+
+
The Ered value of the Cu /Cu redox couple is solvent dependent.
For example, the value is 0.15 V in water, 0.24 V in methanol, and
2
9
1
.19 V in acetonitrile (vs NHE). Therefore, the assay solvent
Figure 4. (a) Changes in fluorescence emission spectrum of BOPHY-PTZ (1 µM)
composition for the redox reaction was optimized. We investigated
the influence of solvent and pH, as shown in Figure S8, BOPHY-PTZ
2+
with Cu concentration (0, 0.001, 0.005, 0.01, 0.025, 0.05, 0.1, 0.2, 0.35, 0.5, 0.75,
2+
1
, 2, 4, 8, 15 µM). (b) Fluorescence intensity changes at 574 nm with Cu
showed a weak fluorescence emission intensities in acetonitrile, concentration. Inset: expanded linear calibration curve.
ethanol, THF, DMF, DMSO, water and other mixture solvents. Upon
2
2
+
the correlation coefficient is R = 0.995. Our method is very
addition of Cu
, BOPHY-PTZ showed a noticeable enhanced
2
+
8-10, 20, 29, 30-40
sensitive, 1.0 nM Cu ion can be easily detected,
and
fluorescence emission in acetonitrile, however, only weak
fluorescence changes were observed in other solvents systems,
indicated that acetonitrile is the best solvent to the redox reactions.
Moreover, as shown in Figure S9, BOPHY-PTZ showed weak
this value is much lower than the maximum safety level of copper in
drinking water (1.3 ppm, 20 μM) defined by the U.S. EPA.
Selectivity of the assay in a complex environment is crucial. To
evaluate the selectivity of the assay, changes in fluorescence
emission spectrum of BOPHY-PTZ in the presence of other metal
ions were investigated. Figure 5 shows the fluorescence emission of
fluorescence emission in CH
3
CN/water solvent mixtures (CH
3
CN:
9
9.75%, 89.75%, 79.75%, 49.75% and 19.75%). However, upon the
2
+
addition of 10 µM Cu
,
significantly enhanced fluorescence
CN-H O mixture solution containing
.25% water. Finally, we investigated fluorescence emission
2
+
BOPHY-PTZ (1 µM) in the presence of 2 µM Cu and 20 µM other
emission was observed in CH
3
2
+
+
+
2+
2+
2+
2+
2+
2+
2+
3+
metal ions (Li , K , Ag , Mg , Ca , Ba , Mn , Ni , Zn , Pb , Fe ,
0
2
+
2+
2
+
Cd and Hg ). No significant fluorescence emission intensity
intensity changes upon addition of 10 µM Cu ions in different pH
buffer-CH CN (CH CN: 99.75%) solvent mixtures (See Figure S10),
and no significant changes was detected in the different pH buffer-
CH CN.
changes were observed in the presence of other metal ions at ten
3
3
2
+
times the concentration of Cu . A competition assay was also
conducted. As Figure shows, no obvious interference was
6
3
detected in the presence of 20 equivalents of the other metal ions.
The fluorescence emission intensity kept mostly unchanged, and
the value was about the same compared with that in the presence
Other important experimental conditions were optimized to get
the best sensing performance. The influence of reaction
temperature on the sensing performance was optimized. As shown
2
+
2
+
of only Cu . In addition, we investigated the influence of some
in Figure S11, upon the addition of 10 equivalents of Cu ions, the
emission intensity quickly reached the maximum at a temperature
of over 20 °C. Figure S12 shows the time-dependent fluorescence
intensity changes of BOPHY-PTZ at 574 nm in the presence of
2
-
-
+
oxidant (O , MnO4-, Cr2O7-, NO2-, NO, ClO ) and Cu . As shown in
+
Figure S13, the addition of 20 µM of those oxidants and Cu has no
obvious effect on the fluorescence emission intensity compared
2
+
2
+
with Cu . The probe BOPHY-PTZ thus shows remarkably high
different concentrations of Cu . The results show that after the
2
+
2
+
selectivity for Cu over the other metal ions, which indicates that
the sensor can meet the requirement for environmental monitoring
related applications.
addition of Cu , the fluorescence emission of BOPHY-PTZ increased
progressively with reaction time, and the reaction was completed in
about 300 s at 20 °C.
Under the optimized experimental conditions, the fluorescence
spectra of the probe BOPHY-PTZ in the presence of different
2
+
concentrations of Cu ions were recorded. As Figure 4 shows, the
BOPHY-PTZ probe displayed very weak fluorescence emission at
5
74 nm as a result of the strong fluorescence quenching ICT process
electron transfer from the donor PTZ moiety to the BOPHY moiety).
Under the experimental conditions, the probe BOPHY-PTZ carried
(
2
+
out redox reaction with Cu . The fluorescence emission increased
Figure 5. Selectivity of the assay. (a) BOPHY-PTZ emission spectral changes in the
presence of different metal ions; (b) Changes in fluorescence intensity of BOPHY-
2
+
progressively with the increase of Cu concentration (0 - 15 µM),
2
+
and the emission intensity at 574 nm was linearly related to the PTZ (1 μM) at 574 nm in the presence of Cu (2 μM) and other metal ions (20 μM
2
+
each).
Cu concentration at 0 - 2 µM. The linear equation is IF = 50.14C +
6
.69, where “IF” and “C” refer to the fluorescence emission
2
+
intensity at 574 nm and the concentration of Cu ions in µM,
respectively, and
4
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Acknowledgements
This work was supported by the National Natural Science
Foundation of China (21561162004), the Natural Science
Foundation of Jilin Province (20150101183JC), the Science and
Technology Development Project (International Collaboration
Program) of Jilin Province (20160414040GH) and the Natural
Science Project of Jinlin Province (20150204030YY).
Conflicts of interest
There are no conflicts to declare.
Notes and references
1
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J. S. Valentine and P. J. Hart, Proc. Natl. Acad. Sci. USA, 2003,
100, 3617.
D. R. Brown and H. Kozlowski, Dalton Trans., 2004, 1907.
Figure 6. Changes in fluorescence intensity of BOPHY-PTZ (1 µM) in the presence
1
2+
2+
2+
2+
of Cu (2 µM) and other metal ions (20 µM each). (1) Cu , (2) Cu + Mn , (3)
2
2
+
2+
2+
+
2+
2+
2+
2+
2+
2+
2+
Cu + Pb , (4) Cu + Ag , (5) Cu + Ca , (6) Cu + Ni , (7) Cu + Ba , (8) Cu
+
+
2
+
2+
2+
2+
+
2+
3+
2+
2+
2+
Cd , (9) Cu + Hg , (10) Cu +Li , (11) Cu + Fe , (12) Cu + Mg , (13) Cu + K ,
3
4
2
+
2+
(
14) Cu + Zn .
The assay was also tested using environmental water samples.
The practical application of our method was evaluated by
5
2
+
determination of the recovery of spiked Cu ions in tap water
samples. Firstly, the tap water samples were filtered through a
nitrocellulose filter (0.22 μM). Subsequently, different
6
7
H. Ghrefat and N. Yusuf, Jordan, Chemosphere., 2006, 65
2114.
L. J. Fan and W. E. Jones, J. Am. Chem. Soc., 2006, 128, 6784.
,
2
+
8
9
concentrations of Cu (25, 50, 100 nM) were spiked into the tap
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Am. Chem. Soc., 2006, 128, 10.
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1 J. Zong, X. l. Yang, A. Trinchi, S. Hardin, I. Cole, Y. H. Zhu, C. Z.
water samples, and their recovery values were determined (Table
1
). Satisfactory recovery was obtained. The results clearly prove
1
1
that the BOPHY-PTZ probe can be used for practical analysis of
complex environmental samples.
Li, T. Muster and G. Wei, Biosens. Bioelectron., 2014, 51
330.
,
2
+
Table 1. Cu recovery in tap water samples.
1
2 M. G. Choi, S. Y. Cha, H. K. Lee, H. L. Jeon and S. K. Chang,
Chem. Commun., 2009, 7390.
Added
nM)
Found
(nM)
RSD (%,
n=3)
1
1
1
3 J. W. Liu and Y. Lu, J. Am. Chem. Soc., 2007, 129, 9838-9839.
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Sample
Recovery (%)
(
41, 1130.
6 S. Tamgho, A. Hasheminasab, J. T. Engle, V. N. Nemykin and
C. J. Ziegler, J. Am. Chem. Soc., 2014, 136, 5623.
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1
2
3
25.0
50.0
24.5 ± 0.9
49.3 ± 0.9
99.5 ± 1.0
98.2
98.6
99.5
1.04
1.15
1.19
1
1
1
2
100.0
Conclusions
In summary, a novel D-π-A type fluorine boron compound
BOPHY-PTZ was successfully synthesized and employed as a
2
+
highly selective and sensitive fluorescence sensor for Cu . The 21 Z. R. Grabowski, K. Rotkiewicz, W. Rettig, Chem. Rev. 2003,
1
03, 3899.
effective ICT process from PTZ to BOPHY caused efficient
quenching of the probe fluorescence. However, when PTZ was
oxidized to phenothiazine-5-oxide (PTZO) upon the addition of
2
2
2 X. M. Gao, Y. L. Zhang, B. H. Wang, Org. Lett., 2003, 5, 4615.
3 C. H. Dai, D. L. Yang, W. J. Zhang, B. Q. Bao, Y. X. Cheng, L. H.
Wang, Polym. Chem., 2015, 6, 3962.
2
+
Cu ions, the ICT process was effectively broken, and the dye 24 J. Yang, Y. J. Chang, M. Watanabe, Y. S. Hon and J. Chow, J.
BOPHY-PTZO emitted strong fluorescence. The assay exhibits
Mater. Chem., 2012, 22, 4040.
5 Q. Huaulmé, A. Mirloup, P. Retailleau and R. Ziessel, Org.
Lett., 2015, 17, 2246.
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Chem., 2008, 112, 12557.
27 H. P. Zhou, P. C. Xue, Y. Zhang, X. Zhao, J. H. Jia, X. F. Zhang,
2
high sensitivity and selectivity for Cu ions. It is simple, fairly
+
2
2
fast and convenient. The BOPHY-PTZ probe show good
2
+
potential for quantitative determination of Cu ions in
analytical and environmental monitoring related applications.
X. L. Liu and R. Lu, Tetrahedron, 2011, 67, 8477.
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Table of Contents Entry
A novel D-π-A type fluorine boron compound BOPHY-PTZ was synthesized and
2
+
employed as a “turn on” fluorescence probe for the sensitive detection of Cu ions.