Novel coumarin-based containing denrons selective fluorescent chemosesor for sequential recognition of Cu2+ and PPi

Article abstract of DOI:10.1016/j.tet.2019.02.024

In this study, we have successfully synthesized a novel coumarin-based dendrons derivative CD and its chemical structure was characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. The sensor CD showed an obvious “on-off” fluorescence quenching response toward Cu²⁺ with a maximum quenching efficiency of 99.8%. The CD-Cu²⁺ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions. The detection limit of the sensor CD was 0.29 × 10^?6 M to Cu²⁺ and 2.39 × 10^?9 M to PPi. In addition, the sensor CD showed a 1:1 binding stoichiometry to Cu²⁺ and the sensor CD-Cu²⁺ showed a 2:1 binding stoichiometry to PPi in CH₃CN/HEPES buffer medium (9:1 v/v, pH = 7.2). The stable pH range of sensor CD to Cu²⁺ and CD-Cu²⁺ to PPi was from 3 to 8.

Full text of DOI:10.1016/j.tet.2019.02.024

Accepted Manuscript
Novel coumarin-based containing denrons selective fluorescent chemosesor for
2+
sequential recognition of Cu and PPi
Chongyang Zhao, Jian Chen, Duanlin Cao, Jianlong Wang, Wenbing Ma
PII:
S0040-4020(19)30174-7
https://doi.org/10.1016/j.tet.2019.02.024
TET 30147
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 30 November 2018
Revised Date: 31 January 2019
Accepted Date: 8 February 2019
Please cite this article as: Zhao C, Chen J, Cao D, Wang J, Ma W, Novel coumarin-based containing
2+
denrons selective fluorescent chemosesor for sequential recognition of Cu and PPi, Tetrahedron
(2019), doi: https://doi.org/10.1016/j.tet.2019.02.024.
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please
note that during the production process errors may be discovered which could affect the content, and all
legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT
O
O
O
O
Cu2+
H
N
N
N
N
O
O
O
O
N
N
O
O
O
O
Cu2+
Fluorescence-On
Fluorescence-Off
PPi
PPi
Cu2+
Cu2+
N
O
O
O
O
O
O
O
O
P
P
O
O
N
N
O
Cu2+
O
Cu2+
N
N
O
O
O
O
O
O
O
N
Fluorescence-On

ACCEPTED MANUSCRIPT
Novel coumarin-based containing denrons selective fluorescent
chemosesor for sequential recognition of Cu2+ and PPi
Chongyang Zhao a, Jian Chen a, Duanlin Cao a, Jianlong Wang *a, Wenbing Ma a
a School of Chemical Engineering and Technology, North University of China,
Taiyuan 030051, P.R. China
Abstract: In this study, we have successfully synthesized a novel coumarin-based
dendrons derivative CD and its chemical structure was characterized by 1H NMR, 13C
NMR and ESI-HR-MS. The sensor CD showed an obvious “on-off” fluorescence
quenching response toward Cu2+ with a maximum quenching efficiency of 99.8%.
The CD-Cu2+ complex showed an “off-on” fluorescence enhancement response
toward PPi over many competitive anions. The detection limit of the sensor CD was
0.29 ×10-6 M to Cu2+ and 2.39×10-9 M to PPi. In addition, the sensor CD showed a
1:1 binding stoichiometry to Cu2+ and the sensor CD-Cu2+ showed a 2:1 binding
stoichiometry to PPi in CH3CN/HEPES buffer medium (9:1 v/v, pH=7.2). The stable
pH range of sensor CD to Cu2+ and CD-Cu2+ to PPi was from 3 to 8.
Keywords: Fluorescent probe; Coumarin; Dendrons; Cu2+; PPi; On-off-on sensor
1. Introduction
The presence of excessive heavy metal ions may have a serious impact on both
biological systems and nature [1-3]. Fluorescent chemosensors have emerged as an
[4-6]
effective tool for the detection of heavy metal ions
due to their high selectivity,
high sensitivity and low cost. Cu2+ is an essential metal element in human body, and a
too high or too low content of Cu2+ can seriously disturb the normal physiological
[7-9]
activities
and thus cause the occurrence of various diseases [10, 11]. Therefore, it is
important for the identification of Cu2+ by fluorescent chemosensors with high
sensitivity and selectivity [12-16]
.
However, most fluorescent chemosensors show a fluorescence quenching
response due to the paramagnetic nature of Cu2+, which could also be affected by
other quenchers in practical applications. The fluorescent chemosensors for sequential
recognition could effectively eliminate the interference of other quenchers in the
1

ACCEPTED MANUSCRIPT
[17-20]
system, thereby making them more specific for the detection of Cu2+
.
Pyrophosphate (PPi) is the main product of ATP hydrolysis that may cause damage to
the living systems [21-23]. For this reason, much effort has been devoted to developing
highly selective fluorescent probes for the detection of PPi [24-27]. However, a major
problem for the detection of PPi by fluorescent chemosensors is their high selectivity
[28, 29].
over other anions
Thus, there is a practical need to develop more efficient and
specific fluorescent chemosensors for the detection of PPi.
Dendrimers and dendrons are a class of substances with a three-dimensional
dendritic molecular structure, which are widely used in many fields, including drug
[35]
transmission systems [30, 31], fluorescent chemosensors [32-34], catalysts
and liquid
crystal materials [36]. There are various types of fluorescence chemosensors with
dendrons, including pyrene-labeled dendrimers [37], triphenylamine-based Dendron [38]
,
[40]
oligoethylene glycol (OEG)-based polymers [39], chromone-based Dendron
,
1,8-naphthalimide-based dendrons [41] and anthracene-based poly(aryl ether) dendrons
[42]. Such fluorescent chemosensors usually have longer alkanes chains and more ether
and amide groups, which can improve the interaction between molecules and the
selectivity or sensitivity of the probe by adjusting the coordination space and electron
cloud density. However, their applications can be limited by their poor solubility.
Therefore, it is important to develop low-molecular dendrons fluorescent
chemosensors with simple structure and good sensing performance.
[43-45]
Coumarin has been widely used in fluorescence chemosensors
for its large
stokes shift, high photoquantum stability and strong fluorescence, especially in the
detection of heavy metal ions. In this study, a novel coumarin-based dendrons
1
derivative CD was synthesized and characterized by H NMR, 13C NMR and
ESI-HR-MS. Sensor CD showed obvious “on-off” fluorescence quenching response
toward Cu2+ and fluorescence “off-on” behavior toward PPi in CH3CN/HEPES buffer
medium (9:1 v/v, pH=7.2). The color of the test solution showed obviously changes,
indicating that sensors CD could be used for naked-eye detection of Cu2+ and PPi.
2

ACCEPTED MANUSCRIPT
Scheme 1 Synthesis of sensor molecule CD
2. Experimental
2.1. Materials and methods
Compound 4 was synthesized as described in a previous study [46]. Other solvents
and starting materials were purchased from Aladdin and Energy Chemical Reagents
Ltd. Ultrapure water was used through all the tests. The melting points of intermediate
and sensor CD were measured on a WRS-C1 digital melting-point apparatus
(Shanghai, China). The pH of all solutions was adjusted on a PHS-3C pH meter
1
13
(Shanghai, China). The H NMR (400 MHz) and C NMR (100 MHz) spectra were
recorded on a Bruker AVANCE III spectrometer (Switzerland) in CDCl3 solution. The
SEI-MS spectra of intermediate and sensor CD were recorded on a Bruker Solarix XR
Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer. The
UV-spectra of all samples were recorded on a UV-2602 spectrophotometer (Shanghai,
China), and all fluorescence spectra were recorded on a HITACHIF-2500
spectrophotometer (Japan).
2.2. Synthesis
Preparation of solid 1. As described in a previous study [47], 4.25 g (25 mmol) gallic
acid was dissolved in 50 mL MeOH, 1.5 mL concentrated H2SO4 was added, and then
3

ACCEPTED MANUSCRIPT
the mixture was heated to reflux for 12 h. After that, the solvent was removed under
reduced pressure and the mixture was extracted with ethyl acetate. The obtained
mixture was washed twice with water and saturated NaHCO3 solution, and dried over
anhydrous Na2SO4. The crude product obtained was purified by column
chromatography on silica gel (eluent: petroleum ether/ethyl acetate=2:1), and 4.25 g
(23 mmol) white solid 1 was obtained with a 92% yield and a melting point of
199.9-200.5 °C.
Preparation of solid 2 and 3. As described in a previous study [48], 1.84 g (10
mmol) Methyl-3, 4, 5-trihydroxybenzoate and 5.52 g (40 mmol) potassium carbonate
were dissolved in 30 mL 1, 4-dioxane, than 3.78 g (30 mmol) benzyl chloride and
trace amounts of tertiary butyl ammonium iodide were added, and then the mixture
was heated to reflux for 24 h. After that, the mixture was filtered and the solvent was
removed under reduced pressure. The crude product was recrystallized from methanol,
and 1.5 g (3.30 mmol) white solid 2 was obtained with 88% yield and a melting point
of 91.9 °C.
2.0 g (4.4 mmol) solid 2 and 11 mL (220 mmol) hydrazine monohydrate were
dissolved in 15 mL MeOH and 7 mL THF, and then the mixture was heated to 70 ºC
for 12 h. After that, the mixture was cooled to room temperature and the solvent was
removed under reduced pressure. The residue was dissolved in CH2Cl2 and washed
with water, and dried over anhydrous Na2SO4. The crude product obtained was
purified by column chromatography on silica gel (eluent: CH2Cl2/MeOH=95:5), and
1.82 g (4 mmol) white solid 3 was obtained with a 91% yield and a melting point of
121.5-121.7 °C.
Preparation of sensor CD. 0.454 g (1 mmol) solid 3 and 0.245 g (1 mmol) solid
4 were dissolved in 30 mL ethanol, and the mixture was heated to reflux for 2 h. The
crude product was purified by column chromatography on silica gel (eluent:
petroleum ether/ethyl acetate=10:1) to obtain 0.495 g (0.73 mmol) sensor CD.
1
CD: Yield 73%. Orange solid. Mp: 222.6-223.8ºC. H NMR (CDCl3, 400 MHz,
TMS): δ (ppm) 1.08(t, 6H, J=7.2), 3.26(q, 4H, J=7.2 Hz), 5.08(s, 2H), 5.17(s, 4H),
6.38(s, 1H), 6.55(dd, 1H, J1=8.8 Hz, J2=2.4 Hz), 7.22-7.42(m, 18H), 8.48(s, 1H),
4

ACCEPTED MANUSCRIPT
8.68(s, 1H), 10.68(s, 1H). 13C NMR (CDCl3, 100 MHz, TMS): δ (ppm) 12.38, 44.85,
71.22, 75.12, 97.19, 107.31, 108.82, 109.83, 112.49, 127.67, 127.90, 127.94, 128.17,
128.46, 128.53, 130.58, 136.72, 137.64, 140.27, 141.37, 143.09, 151.71, 152.83,
156.91, 162.69, 163.94. HRMS (ESI): m/z calcd for C42H39N3O6 [(M+H)+]: 682.2912,
found 682.2917 (Fig.S.1-S3).
2.3. General procedure for fluorescence spectra experiments
All tests were carried out in the CH3CN/HEPES (9:1, v/v) buffer (pH=7.2)
medium at room temperature. All fluorescence spectra were recorded at an excitation
of 448 nm. The stock solutions of various metal ions and anions (1×10-2 M) were
prepared from chlorine and sodium salts in ultrapure water, respectively. The
concentration of sensor CD was 10 ꢀM in all experiments. The slits of emission and
excitation were 5 nm in all experiments.
3 Results and Discussion
3.1 UV-vis spectral response of sensor CD to Cu2+
1.2
CD
Ag+
Al3+
Ba2+
Ca2+
Cs+
Cu2+
1.0
0.8
0.6
0.4
0.2
0.0
Fe3+
Hg2+
K+
Li+
Mg2+
Na+
Pb2+
Zn2+
350
400
450
500
550
Wavelength(nm)
Fig.1. UV-vis spectra of sensor CD (10 ꢀM) with the addition of different metal ions (10 equiv.) in
CH3CN/HEPES buffer medium (9:1 v/v, pH=7.2). Inset: the color changed of sensor CD (10ꢁµM)
in the absence and presence of Cu2+ (20 equiv.).
In this study, we first investigated the absorption response of sensor CD toward
10 equiv. of different metal ions by UV-vis spectroscopy, including Al3+, Fe3+, Pb2+,
Cu2+, Zn2+, Mg2+, Hg2+, Ba2+, Ca2+, Ag+, Cs+, Li+, K+ and Na+, all tests were carried
out in CH3CN/HEPES buffer medium (9:1 v/v, pH=7.2). As shown in Fig.1, sensor
5

ACCEPTED MANUSCRIPT
CD did not respond to other metal ions except that the addition of Cu2+ resulted in a
significant red shift of 445 nm to 490 nm. The color of the solution changed from
yellow to orange (Inset of Fig.1), indicating that sensors CD could be used for
effective naked-eye detection of Cu2+.
1.0
0.8
0.6
0.4
0.2
0.0
CD
CD + 0.1 eq Cu2+
CD + 0.2 eq Cu2+
CD + 0.3 eq Cu2+
CD + 0.4 eq Cu2+
CD + 0.5 eq Cu2+
CD + 0.6 eq Cu2+
CD + 0.7 eq Cu2+
CD + 0.8 eq Cu2+
CD + 0.9 eq Cu2+
CD + 1.0 eq Cu2+
CD + 1.1 eq Cu2+
CD + 1.2 eq Cu2+
CD + 1.3 eq Cu2+
CD + 1.4 eq Cu2+
CD + 1.5 eq Cu2+
350
400
450
500
550
600
Wavelength(nm)
Fig.2. UV-vis spectra of sensor CD (10 ꢀM) with the addition of various concentrations [0, 0.1,
0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 and 1.5 equiv.] of Cu2+ in CH3CN/HEPES
buffer medium (9:1 v/v, pH=7.2). Inset: The color changed of the solution with different
concentrations Cu2+.
As shown in Fig.2, the absorption intensity of sensor CD at 350 nm and 490 nm
increased dramatically with the gradual addition of Cu2+ up to 1.5 equiv. into 10 ꢀM
sensor CD in CH3CN/HEPES buffer medium (9:1 v/v, pH=7.2). In addition,
isosbestic points at 379 nm and 453 nm could be clearly observed, thus confirming
that sensor CD and CD-Cu2+ complex existed in equilibrium. In addition, the inset of
Fig. 2 shows that the color of the solution has changed from yellow to orange at a
Cu2+ concentration of 0.3 equiv., and the color becomes gradually dark with the
increase of the Cu2+ concentration.
3.2. Fluorescence responses of sensor CD towards Cu2+
6

ACCEPTED MANUSCRIPT
5000
4000
3000
2000
1000
0
CD
Ag+
Al3+
Ba2+
Ca2+
Cs+
Fe3+
Hg2+
K+
Li+
Mg2+
Na+
Pb2+
Zn2+
Cu2+
500
550
600
650
Wavelength (nm)
Fig.3. Fluorescence spectra of sensor CD (10 ꢀM) in the presence of different metal ions (10
equiv.) in CH3CN/HEPES buffer medium (9: 1 v/v, pH=7.2) at excitation of 448 nm. Inset:
changes in fluorescence of sensor CD (10ꢁµM) in the absence and presence of Cu2+ (20 equiv.)
under UV light at 365ꢁnm.
To further illustrate the sensing ability of sensor CD toward Cu2+, we explored
the selective recognition of excess of different metal ions by sensor CD. At an
excitation wavelength of 448 nm, the fluorescence spectra showed no significant
fluorescence change and wavelength shift except Cu2+, which showed obvious
fluorescence quenching response toward Cu2+ upon the addition of 10 equiv. of metal
ions, and the fluorescence intensity decreased from 4198 to 6.962.
6000
CD and CD+ other meatal ions
CD+Cu2+ and CD+ other meatal ions+ Cu2+
4500
Fe3+
Al3+
Cs+
Ag+
Na+ Ca2+
Li+
Pb2+
Hg2+
Zn2+
K+
Mg2+
Ba2+
CD
3000
1500
0
Cu2+
Fig.4. Fluorescence intensity of sensor CD (10 ꢀM) with selected metal ions (10 equiv.) in the
absence (black points) or presence (red points) of Cu2+ (10 equiv.).
The interference tests were carried out in order to explore the effects of other
ions on the identification of Cu2+. As shown in Fig.4, the fluorescence intensity of
7

ACCEPTED MANUSCRIPT
other metal ion solution showed obvious fluorescence quenching with the addition of
10 equiv. of Cu2+ ions. However, these metal ions did not interfere with the
recognition of Cu2+ ions. Moreover, sensor CD showed high specificity to Cu2+ over a
wide range of metal ions.
5000
6000
0
4800
4000
3000
2000
1000
0
3600
2400
1200
0
Cu2+
5 equiv.
0.0
0.2
0.4
0.6
0.8
1.0
Mole Fraction of Cu2+
500
550
600
650
Wavelength (nm)
Fig.5. Fluorescence spectra of 10 ꢀM sensor CD with the addition of various concentrations [0,
0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 3.0, 4.0 and 5.0 equiv.] of Cu2+
in CH3CN/HEPES buffer medium (9:1 v/v, pH=7.2) at an excitation of 448 nm. The inset plots
showed that sensor CD formed a 1:1 complex with Cu2+.
As shown in Fig.5, the fluorescence intensity showed a significant decrease at
512 nm with the addition of Cu2+ to 10 ꢀM sensor CD, and the quenching efficiency
reached a maximum of 99.8% [(I0-I)/I0×100%] with the addition of 5equiv. of Cu2+.
However, as the Cu2+ concentration was 2 times, the fluorescence intensity showed no
significant changes (Fig.S7). The binding constant Ka was 3.39×104 M-1 (R2=0.9896,
Fig. S4). The detection limit was calculated to be 0.29 ꢀM according to the formula
LOD=3σ/k (Fig. S5). The Job plots with fluorescence titrations showed a minimum at
about 0.5 mol fractions, indicating that sensor CD formed a 1:1 complex with Cu2+.
3.3. Fluorescence responses of CD-Cu2+ complex to PPi
8

ACCEPTED MANUSCRIPT
5000
4000
3000
2000
1000
0
Br-
Only CD
Cl-
CO32-
F-
PPi
-
HCO3
HSO3-
I-
NO2-
NO3-
OAC-
S2-
SO32-
SO42-
CD-Cu2+
500
550
600
650
Wavelength (nm)
Fig.6. Fluorescence spectra of 10 ꢀM CD-Cu2+ complex with the addition of 10 equiv. different
anions in CH3CN/HEPES buffer medium (9:1 v/v, pH=7.2).
Considering that the complex CD-Cu2+ may interact with anions by
demetallization, we further investigated the fluorescence response of the CD-Cu2+
-
complex to 10 equiv. of various anions, including F-, Cl-, Br-, I-, PPi, OAc-, HCO3 ,
CO3 , HSO3 , SO3 , SO4 , S2-, NO3 and NO2 in CH3CN/HEPES buffer medium (9:
1 v/v, pH=7.2). The probe CD-Cu2+ was prepared in situ by adding 10 equiv. of Cu2+
to sensor CD to determine the selectivity of sensor CD-Cu2+ toward 10 equiv. of
different anions. As shown in Fig.6, only PPi responded obviously to the sensor
CD-Cu2+, which the fluorescence intensity could be recovered to 4372 au with
addition of 10 equiv. PPi, indicating that CD-Cu2+ could act as a fluorescence
2-
-
2-
2-
-
-
“turn-on” PPi sensor.
CD-Cu2++PPi and CD-Cu2++PPi+other ions
CD-Cu2+ and CD-Cu2++other ions
6000
SO42-
-
HCO3
-
SO32-
PPi
Cl-
-
OAc-
NO2
I-
HSO3
F-
NO3-
2-
Br-
CO3
S2-
4000
2000
0
CD-Cu2+
Fig.7. Fluorescence intensity of CD-Cu2+ (10 ꢀM) with selected anions (10 equiv.) in the absence
(red points) or presence (black ponits) of PPi (10 equiv.).
9

ACCEPTED MANUSCRIPT
To further examine whether sensor CD-Cu2+ could act as an ion-selective
chemosensor for PPi, competitive experiments (Fig.7) were carried out in the
presence of 10 equiv. of PPi and 10 equiv. of other anions. The results showed that
the fluorescence emission spectrum of sensor CD-Cu2+ with PPi was not affected by
subsequent addition of competitive anions, indicating that sensor CD-Cu2+ had high
specificity for the detection of PPi among many anions.
3500
5000
4000
3000
3000
2.0 equiv.
2000
2500
1000
PPi
2000
1500
1000
500
0
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Mole Fraction of PPi
0
500
550
Wavelength (nm)
600
650
Fig.8. Fluorescence spectra of 10 ꢀM CD-Cu2+ in the presence of various concentrations [0, 0.1,
0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 and 2.0 equiv.] of
PPi in CH3CN/HEPES buffer medium (9:1 v/v, pH=7.2) at an excitation of 448 nm. The inset
plots indicated that sensor CD-Cu2+ formed a 2:1 complex with PPi.
As seen from Fig.8, the fluorescence intensity of sensor CD-Cu2+ increased
gradually as the PPi concentration increased from 0 to 2.0 equiv., and it was recovered
to 88 % (relative to sensor CD) upon the addition of 2.0 equiv. of PPi. The detection
limit of CD-Cu2+ for PPi was determined to be 2.39×10-9 M (Fig. S6). The Job plots
with fluorescence titrations exhibited a maximum at about 0.35 mol fractions,
indicating that CD-Cu2+ formed a 2:1 complex with PPi.
3.4. The possible mechanism of sensor CD for Cu2+ and PPi
10

ACCEPTED MANUSCRIPT
Fig.9. 1H NMR titration spectra of sensor CD upon addition of 0.1 equiv. Cu2+
O
O
O
O
O
Cu2+
H
N
N
N
N
O
O
O
N
N
O
O
O
O
Cu2+
Fluorescence-On
Fluorescence-Off
PPi
PPi
Cu2+
Cu2+
N
O
O
O
O
O
O
O
O
P
P
O
O
N
N
O
Cu2+
Cu2+
O
N
N
O
O
O
O
O
O
O
N
Fluorescence-On
Scheme 2 The possible mechanism of CD-Cu2+ with PPi
11

ACCEPTED MANUSCRIPT
The fluorescent PET (photo induced electron transfer) sensors are usually
connected by fluorophore and receptor through non-conjugated system. The
fluorescence will show significantly fluorescence quenching or enhancement response
due to coordinate with other metal ions and no shift of emission spectra. When sensor
CD interacted with Cu2+, resulting in a significant fluorescence quenching response,
and the quenching efficiency reached a maximum of 99.8%.
1H NMR titration experiments were conducted in order to better understand the
binding mode between sensor CD and Cu2+ (Fig.9). As the Cu2+ concentration
increases, the N-H signals gradually disappear and the schiff base C-H signals shift to
higher δ values with respect to sensor CD. The broadening of signals can also be
affected by coordination. The molecular ion peak (ESI-MS) at 821.2169 [sensor CD +
Cu2+ + DMSO; m/z calcd for 821.2196] indicates an approximately 1:1 complexation
between sensor CD and Cu2+.
After the addition of PPi, PPi could act with Cu2+ ion to pull it out of the
coordination system, and the electron effect could be restored and the fluorescence
could be enhanced. However, due to the influence of some factors in the system, such
as the increase of water content, the fluorescence could be recovered to a maximum of
88% of the original intensity. Thus, considering the obvious “on-off” fluorescence
response and no shift of emission spectra with increasing Cu2+ concentration, the PET
mechanism was speculated.
3.5. Reversibility of sensor CD for Cu2+ and PPi
5000
on
4000
3000
2000
1000
0
off
0
1
2
3
4
Cycles
12

ACCEPTED MANUSCRIPT
Fig.10. The sequential recognition of sensor CD (10 ꢀM) upon alternate addition of Cu2+ and PPi
in CH3CN/HEPES (9: 1, v/v) HEPES buffer (pH=7.2) (λex=448 nm).
Here, we took Cu2+ and PPi as the input signal and fluorescence intensity as the
output signal to explore the stability of sensor CD for the identification of Cu2+ and
PPi. After four cycles, the fluorescence quenching response was stable with the
addition of Cu2+ ion, but the recovery of the fluorescence intensity showed a slight
decrease with the addition of PPi. Fig.10 showed that the sequential recognition of
Cu2+ and PPi by sensor CD could be achieved for at least four times. Thus, sensor CD
had good stability in detection of Cu2+ and PPi, which further indicated that sensor
CD could be widely used in practical applications.
3.6 Effect of pH
5000
CD
CD+Cu2+
CD-Cu2++PPi
4000
3000
2000
1000
0
4
6
8
10
12
pH
Fig.11. Changes of the fluorescence intensity of sensor CD towared Cu2+ (10 equiv.) an=d PPi (10
equiv.) (10 ꢀM) over a wide range of pH in CH3CN/HEPES buffer medium (9:1 v/v) at room
temperature.
We also investigated the effect of pH on the identification of Cu2+ and PPi by
sensor CD. As seen in Fig. 11, sensor CD showed stable fluorescence intensity at pH
3-8 with and without Cu2+ and PPi. However, the fluorescence intensity of sensor CD
and CD-Cu2+ decreased obviously at pH 8-12. At pH>12, the fluorescence intensity of
both sensor CD-Cu2+ and sensor CD did not recover with the addition of PPi. Thus,
the chemical structure of probe CD could be damaged under strong alkaline
conditions, which made sensor CD to lose its ability to coordinate with ions.
13

ACCEPTED MANUSCRIPT
4. Conclusions
In this study, we have successfully prepared a novel coumarin-based containing
dendrons derivative CD. As 10 equiv. of different metal ions was added, sensor CD
showed an obvious fluorescence quenching response to Cu2+ ion, and the quenching
efficiency was as high as 99.8%. As 10 equiv. of different anions was added, sensor
CD-Cu2+ showed an obvious fluorescence enhancement response to PPi, and the
fluorescence recovery efficiency was 88%. Sensor CD showed a 1:1 binding
stoichiometry to Cu2+ and sensor CD-Cu2+ showed a 2:1 binding stoichiometry to PPi
in CH3CN/HEPES buffer medium (9: 1 v/v, pH=7.2). The detection limits were 0.29
×10-6 M to Cu2+ and 2.39×10-9 M to PPi, indicating high sensitivity. In addition, cyclic
response test showed that sensor CD had good stability in identifying Cu2+ and PPi.
The pH test showed that the optimal pH range was from 3 to 8, indicating that sensor
CD could be used under acid and neutral conditions.
References
[1] Zhuang P, McBride M, Xia HP, Li NY, Li ZA. Sci. Total Environ. 2009; 407:
1551-1561.
[2] Nolan EM, Lippard SJ. Chem. Rev. 2008; 108: 3443-3480.
[3] Lopez-Serrano D, Solano F, Sanchez-Amat A. Microbiology 2007; 153:
2241-2249.
[4] Bi JH, Fang MX, Wang JB, Xia SA, Zhang YB, Zhang JT, Vegesna G, Zhang SW,
Tanasova M, Luo FT, Liu HY. Inorg. Chim. Acta 2017; 468: 140-145.
[5] Kumar A, Ahmed N. New J. Chem. 2017; 41: 14746-14753.
[6] Fan L. J. Fluoresc. 2017; 27: 1331-1337.
[7] Liu KK, Zhang LN, Zhu LN, Zhang R, Li XZ, Kong DM. Sens. Actuators B
Chem. 2017; 247: 179-187.
[8] Gaggelli E, Kozlowski H, Valensin D, Valensin G. Chem. Rev. 2006; 106:
1995-2044.
[9] Tavallali H, Deilamy-Rad G, Moaddeli A, Asghari K. Sens. Actuators B Chem.
2017; 244: 1121-1128.
[10] Andrews NC. Curr. Opin. Chem. Biol. 2002; 6: 181-186.
14

ACCEPTED MANUSCRIPT
[11] Hung YH, Bush AI, Cherny RA. J. Biol. Inorg. Chem. 2010; 15: 61-76.
[12] Murugan AS, Vidhyalakshmi N, Ramesh U, Annaraj J. Sens. Actuators B
Chem. 2018; 274: 22-29.
[13] Gu B, Huang LY, Xu ZF, Tan Z, Hu M, Yang ZT, Chen YX, Peng C, Xiao
WP, Yu DH, Li HT. Sens. Actuators B Chem. 2018; 273: 118-125.
[14] Wang P, Fu JX, Yao K, Chang YX, Xu KX, Xu YQ. Sens. Actuators B Chem.
2018; 273: 1070-1076.
[15] Fu Y, Ding CQ, Zhu AW, Deng ZF, Tian Y, Jin M. Anal. Chem. 2013; 85:
11936-11943.
[16] Han YY, Ding CQ, Zhou J, Tian Y. Anal. Chem. 2015; 87: 5333-5339.
[17] Razi SS, Srivastava P, Ali R, Gupta RC, Dwivedi SK, Misra A. Sens
Actuators B: Chem 2015; 209: 162-171.
[18] Wang YP, Qiu DL, Li MN, Liu YJ, Chen HB, Li HM. Spectrochim Acta A
2017; 185: 256-262.
[19] Wei TB, Li H, Wang QQ, Lu TT, Zhu YR, Lin Q, Zhang YM. Supramol
Chem 2017; 29: 153-159.
[20] Mohandoss S, Sivakamavalli J, Vaseeharan B, Stalin T. Sens Actuators B:
Chem 2016; 234: 300-315.
[21] Russell RGG. Bone 2011; 49: 2-19.
[22] Li YM, Shi J, Wu X, Luo ZF, Wang FL, Guo QX. Cell Biochem. Funct. 2009; 27:
417-423.
[23] Li Y, Dong XH, Zhong C, Liu ZH, Qin JG. Sens. Actuators B Chem. 2013; 183:
124-128.
[24] Kim MJ, Swamy KMK, Lee KM, Jagdale AR, Kim Y, Kim SJ, Yoo KH, Yoon
J. Chem. Commun. 2009; 46: 7215-7217.
[25] Guo MM, Dong PY, Feng Y, Xi XG, Shao R, Tian XH, Zhang BC, Zhu MZ,
Meng XM. Biosens. Bioelectron. 2017; 90: 276-282.
[26] Dong ZM, Wang W, Qin LY, Feng J, Wang JN, Wang Y. J. Photoch. Photobio.
A. 2017; 335: 1-9.
[27] Liu Z, Peng CN, Lu ZX, Yang XF, Pei MS, Zhang GY. Dyes Pigments 2015; 123:
15

ACCEPTED MANUSCRIPT
85-91.
[28] Yang SJ, Feng WY, Feng GQ. Analytica Chimica Acta 2018; 1034: 119-127.
[29] Wang Y, Hou XF, Li ZS, Zhou QH, Lei MM, Hu SS, Wu XP, Li CM, Xu ZH,
Wang Y. Analytical Methods 2018; 10: 5790-5796.
[30] Wali ARM, Zhou J, Ma S, He Y, Yue D, Tang JZ, Gu Z. Int. J. Pharmaceut. 2017;
525: 191-202.
[31] Ma S, Zhou J, Wali ARM, He Y, Xu X, Tang JZ, Gu Z. J Mater Sci: Mater
Med. 2015; 26: 219.
[32] Martín-Serrano Ortiz Á, Stenström P, Mesa Antunez P, Andrén OC, Torres MJ,
Montañez MI, Malkoch M. J Polym Sci Polym Chem. 2018; 56: 1609-1616.
[33] Dimitrova MD, Georgiev NI, Bojinov VB. J Fluoresc 2016; 26: 1091-1100.
[34] Wycisk V, Pauli J, Welker P, Justies A, Resch-Genger U, Haag R, Licha K.
Bioconjugate Chem. 2015; 26: 773-781.
[35] Jillella R, Kim J, Kim KH, Han JW, Oh CH. B Korean Chem. Soc. 2018; 39:
1090-1095.
[36] Concellon A, Liang T, Schenning APHJ, Serrano JL, Romero P, Marcos M. J.
Mater. Chem. C 2018; 6: 1000-1007.
[37] Chen CY, Ito Y, Chiu YC, Wu WC, Higashihara T, Ueda M, Chen WC. J. Polym.
Sci., Pol. Chem. 2012; 50: 297-305.
[38] Liu F, Ding C, Jin M, Tian Y. Analyst 2015; 140: 3285-3289.
[39] Liu L, Li W, Yan J, Zhang A. J. Polym. Sci., Pol. Chem. 2014; 52: 1706-1713.
[40] Bai X, Yan J, Qin JC, Yang ZY. Inorganica Chimica Acta 2018; 474: 44-50.
[41] Sun J, Qian Y. Chinese J. Org. Chem. 2015; 35: 1104-1111.
[42] Sivaraman G, Iniya M, Anand T, Kotla NG, Sunnapu O, Singaravadivel S,
Chellappa D. Coordin. Chem. Rev. 2018; 357: 50-104.
[43] Fang MX, Adhikari R, Bi JH, Mazi W, Dorh N, Wang JB, Conner N, Ainsley J,
Karabencheva-Christova TG, Luo FT, Tiwari A, Liu HY. J. Mater. Chem. B 2017; 5:
9579-9590.
[44] Yang YT, Bai BZ, Jin M, Xu ZD, Zhang JC, Li W, Xu WZ, Wang X, Yin CX.
Biosens. Bioelectron. 2016; 86: 939-943.
16

ACCEPTED MANUSCRIPT
[45] Chen XZ, Ma XD, Wang HM, Wang M, Zhang MM, Gao G, Liu JJ, Hou SC.
New J. Chem. 2017; 41: 8026-8030.
[46] Wu JS, Liu WM, Zhuang XQ, Wang F, Wang PF, Tao SL, Zhang XH, Wu SK,
Lee ST. Org. Lett. 2007; 9: 33-36.
[47] Yin H, Cheng K. U.S. Patent No. 9517993.
[48] Rajamalli P, Prasad E. Org. lett. 2011; 13: 3714-3717.
17

ACCEPTED MANUSCRIPT
ꢀ
ꢀ
A novel coumarin-based containing denrons derivative CD was synthesized.
The sensor CD can be used to sequential detect Cu2+ and PPi in CH3CN/HEPES
buffer medium.
ꢀ The detection limits for Cu2+ and PPi were estimated to be 0.29×10-6 and
2.39×10-9 M, respectively.