Sensitive and Selective Fluorescent and Colorimetric Sensor for Ag+ Based on the Supramolecular Self-Assembly in Semi-Water

Article abstract of DOI:10.1002/cjoc.201600809

Specific recognition of ultratrace levels of ions in semi-water using super-quicker methods is still a challenge for environmental monitoring. Herein we report a fluorescent and colormetric sensor (ZH) based on supramolecular self-assembly, whose structure was destroyed by the addition of ultratrace of silver ions. The process promoted either naked eye visible color changes or fluorescence intensity quenched in conjunction with a wide pH range. Systematic studies revealed very high selectivity (0.07 μmol/L) for silver ions, and other common cations, e.g., Hg²⁺, Cu²⁺, Cd²⁺, Pb²⁺ had nearly no influence on the sensing behavior. This sensor also served as a multiple use of component in sensing materials by addition of I^? into the mixture of ZH and Ag⁺ (about 5 times). What's more, ZH containing filter paper emerged distinct color and fluorescence changes upon exposure to silver (Ag⁺), which could be used as a portable method to undertake field testing for Ag⁺.

Full text of DOI:10.1002/cjoc.201600809

FULL PAPER
DOI: 10.1002/cjoc.201600809
Sensitive and Selective Fluorescent and Colorimetric
＋
Sensor for Ag Based on the Supramolecular Self-Assembly in
Semi-Water
Taibao Wei,* Haili Zhang, Wenting Li, Wenjuan Qu, Junxia Su, Qi Lin, Youming Zhang,
and Hong Yao
Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China; Key Laboratory
of Polymer Materials of Gansu Province; College of Chemistry and Chemical Engineering, Northwest Normal
University, Lanzhou, Gansu 730070, China
Specific recognition of ultratrace levels of ions in semi-water using super-quicker methods is still a challenge
for environmental monitoring. Herein we report a fluorescent and colormetric sensor (ZH) based on supramolecular
self-assembly, whose structure was destroyed by the addition of ultratrace of silver ions. The process promoted ei-
ther naked eye visible color changes or fluorescence intensity quenched in conjunction with a wide pH range. Sys-
2
＋
tematic studies revealed very high selectivity (0.07 μmol/L) for silver ions, and other common cations, e.g., Hg ,
2
＋
2＋
2＋
Cu , Cd , Pb had nearly no influence on the sensing behavior. This sensor also served as a multiple use of

＋
component in sensing materials by addition of I into the mixture of ZH and Ag (about 5 times). What’s more, ZH
＋
containing filter paper emerged distinct color and fluorescence changes upon exposure to silver (Ag ), which could
＋
be used as a portable method to undertake field testing for Ag .
＋
Keywords supramolecular self-assembly, silver (Ag ), dual-channel, aqueous solution
Introduction
professional and difficult to operate. Therefore, there
has been a considerable research effort devoted to de-
veloping effective methods for detecting Ag in the
In the past few years, quite a lot of research has been
dedicated to the area of sensing trace transition metal
ions because of their indispensable effects on the bio-
＋
environment. Fluorescence spectrometry and naked-eye
detection methods are particularly attractive due to their
easier operation, obvious comparison, high sensitivity
[
1]
sphere. Silver is one of the most abundant transition
metals in mammals and industry. Silver ions play vital
roles in various biological processes, such as interaction
with DNA, binding to enzymes, destroying bacteria,
preventing electron transport, indicating that the accu-
[6]
and selectivity.
Most of the fluoroscent sensor molecules are com-
posed of an ion recognition unit modified with a fluor-
ophore. Among the various fluorophores, phenazines
have attracted more and more attention due to their ex-
＋
mulation of Ag affects multiple physiological activi-
[
2]
ties in living systems. With the development of sci-
ence and technology, silver and its compounds were
widely used in jewelry, electroplating, imaging indus-
tries, and electrical equipment. It is important to our
production and life, but even trace amounts of Ag can
[7]
cellent photophysical properties. They are found using
in many fields, such as pharmaceutical technology, new
[8]
energy development and industrial dyes. One of the
most important aspect of phenazine derivatives is that
they can be applied to ions and neutral molecules
recognition. What’s more, phenazine derivatives served
as important and versatile building blocks have been
extensively designed to develop the sensors and bio-
sensors over the years.
[
3]
＋
cause irreversible damage to living body. According to
World Health Organization (WHO), the maximum
＋
bearable amount of Ag is 0.5 μmol/L in drinking wa-
[
4]
ter. Up to now, there are some different methods to
＋
detect Ag , such as atomic absorption spectrometry,
In this paper, by considering our research interests
[9]
electrothermal atomic absorption spectrometry, induc-
tively coupled plasma mass spectrometry, inductively
coupled plasma atomic emission spectrometry, ion
and selecting the ideal building blocks, we designed
and synthesized a phenazine derivative ZH (Scheme 1),
＋
which could readily selectively recognize Ag
in
[
5]
chromatography. However, these methods are highly
aqueous solution. It was easy to form the intermolecular
*
E-mail: weitaibao@126.com; Tel.: 0086-0931-7973191
Received November 20, 2016; accepted December 13, 2016; published online XXXX, 2017.
Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cjoc.201600809 or from the author.
Chin. J. Chem. 2017, XX, 1—6
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1

Wei et al.
FULL PAPER
hydrogen bonds and π-π conjugated system among the
molecules of ZH, as a result it had an excellent optical
property to achieve naked-eye colorimetric and fluori-
metric recognition. The supramolecular self-assembly,
including the intermolecular hydrogen bonds and π-π
(KBr) ν: 3115 (NH), 1693 (C＝N); ESI-MS m/z [M＋
H] calcd for C19H N 296.1135; found 297.114 cm .
12 4
＋
–1
Results and Discussion
＋
The sensor could only recognize Ag over other
metal ions. The colormetric and fluorimetric sensing
abilities were primarily investigated by adding DMSO
conjugated system, was rapidly destroyed by addition of
＋
Ag leading to significant fluorescent intensity and
obvious color changes from yellow to light pink.
2
solution of various metal ions to the DMSO/H O (V/V,
Scheme 1 Synthetic procedures of sensor ZH
1∶1; buffered with HEPES, pH＝7.20) solutions of
sensor ZH separately. The fluorescent intensity wa＋s
sharply decreased at 548 nm with the addition of Ag
(
Figure 1). Besides, evident color change (from yellow
to light pink) was observed, corresponding to the ab-
sorption peaks at 403.5 nm decreased with the addition
＋
of Ag (Figure 2). The fluorescence ON-OFF behavior
and obvious color change, in particular, suggest that the
supramolecular self-assembly was disintegrated. No
significant UV-vis or fluorescence spectra change was
3
＋
2＋
observed when solutions of other cations (Fe , Hg ,
Ca , Cu , Co , Ni , Cd , Pb , Zn , Cr , Mg )
Experimental
2
＋
2＋
2＋
2＋
2＋
2＋
2＋
3＋
2＋
General information and materials
were added to the ZH solution. Thus, ZH could selec-
＋
tively instantly (dual-channel) detect Ag in DMSO/
H O (V/V, 1∶1; buffered with HEPES, pH＝7.20).
2
All reagents were gained commercially for synthesis
and without further purification during experiment pro-
3
＋
2＋
＋
2＋
2＋
gress. All the cations Fe , Hg , Ag , Ca , Cu ,
2
＋
2＋
2＋
2＋
2＋
3＋
2＋
Co , Ni , Cd , Pb , Zn , Cr , and Mg were
added in the form of perchlorate salts, which were pur-
chased from Alfa-Aesar Chemical, and stored in a vac-
uum desiccator. Doubly distilled water was used
1
13
throughout the experiment. H NMR and C NMR
spectra were recorded on a Mercury-400BB spectrome-
1
ter at 600 MHz. H chemical shifts are reported down-
field from tetramethylsilane (TMS, δ scale with solvent
resonances as internal standards). UV-vis spectra were
recorded on a Shimadzu UV-2550 spectrometer. The
fluorescence spectra were recorded with a Shimadzu
RF-5301 spectrofluorimeter. Melting points were meas-
ured on an X-4 digital melting-point apparatus (uncor-
rected). Infrared spectra were performed on a Digilab
FTS-3000 FT-IR spectrophotometer. All reagents used
were of analytical grade.
–
5
Figure 1 Fluorescence spectra (λex＝415 nm) of ZH (2×10
3
＋
2＋
＋
2＋
2＋
mol/L) with different metal ions: Fe , Hg , Ag , Ca , Cu ,
2
＋
2＋
2＋
2＋
2＋
3＋
2＋
Co , Ni , Cd , Pb , Zn , Cr , Mg (10 equiv., respective-
ly) in the DMSO/H O (V/V, 1∶1; buffered with HEPES, pH＝
.20). Inset: visual fluorescence emission of probe ZH upon ad-
2
Synthesis and characterization of sensor ZH
7
2
,3-Diamino-phenazine (0.42 g, 2.0 mmol), benzal-
dehyde (0.233 g, 2.2 mmol) and five drops acetic acid
AcOH) were combined in 85 ℃ absolute DMF (20
dition of different metal ions.
(
The sensor needed to demonstrate high selectivity
for the target analyte over other possible interfering
metal ions. The variations of UV-vis absorbance and
mL) (Scheme 1). The solution was stirred and refluxed
for 8 h, after cooling to room temperature, the brown
precipitate was filtrated, washed with hot absolute eth-
anol three times, recrystallized with DMF to get brown
fluorescence of ZH in DMSO/H
2
O (V/V, 1∶1; buffered
with HEPES, pH＝7.20) binary solutions caused by the
3
＋
2＋
2＋
2＋
2＋
2＋
2＋
2＋
powdery product.
cations (Fe , Hg , Ca , Cu , Co , Ni , Cd , Pb ,
Zn , Cr , Mg , Au ) were investigated (Figures 3, 4
and Figure S10). Form the bar diagram, we could easily
1
2＋
3＋
2＋
3＋
ZH: yield 80%; m.p.＞300 ℃; H NMR (DMSO-d
00 MHz) δ: 13.45 (s, 1H), 8.51 (s, 1H), 8.37 (d, J＝6
Hz, 2H), 8.25 (d, J＝18 Hz, 3H), 7.89 (d, J＝6 Hz, 2H),
6
,
6
consider that the effects on emission and absorption
intensity of ZH and Ag solutions upon addition of
13
＋
7
.66 (d, J＝6 Hz, 3H); C NMR (DMSO-d
6
, 150 MHz)
δ: 159.90, 149.25, 142.25, 142.08, 140.88, 140.86,
various cations were almost negligible. Therefore, it was
1
1
40.62, 140.23, 132.22, 130.16, 129.87, 129.86, 129.60,
29.43, 129.23, 128.18, 115.23, 109.87, 106.29; IR
clear that other ions’ interference was negligible during
the detection of Ag . These results further suggested
＋
2
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Chin. J. Chem. 2017, XX, 1—6

＋
Fluorescent and Colorimetric Sensor for Ag
＋
rescence spectra, upon addition of Ag to receptor ZH,
the emission and the absorption were both gradually
decreased at 548 and 403.5 nm respectively. The detec-
＋
tion limits of ZH for Ag calculated on the basis of
–
7
3
×
σ/m were 2.92×10 mol/L for fluorescence and 7.73
–
8
10 mol/L for absorption spectra respectively (Fig-
[
10]
ures S6 and S7),
which are both far lower than the
＋
index of WHO for Ag in drinking water (less than
.05 μmol/L).
0
–
5
Figure 2 UV-vis spectra responses of ZH (2×10 mol/L) with
3
＋
2＋
＋
2＋
2＋
2＋
2＋
different metal ions: Fe , Hg , Ag , Ca , Cu , Co , Ni ,
Cd , Pb , Zn , Cr , Mg (10 equiv., respectively) in the
2
＋
2＋
2＋
3＋
2＋
DMSO/H O (V/V, 1∶1; buffered with HEPES, pH＝7.20). Inset:
2
photograph of ZH upon addition of different metal ions.
＋
that ZH could be used as a sensor for Ag over a wide
range of cations.
ZH and ZH + metal ions
5
4
3
2
1
00
00
00
00
00
0
Figure 5 Fluorescence spectra of ZH in the presence of differ-
+
ZH+ Ag + metal ions
＋
ent concentrations of Ag in DMSO/H O (V/V, 1∶1; buffered
2
with HEPES, pH＝7.20) solutions. Inset: a plot of fluorescence
＋
intensity depending on the concentration of Ag in the range
from 0 to 17 equivalents, the detection wavelength was 415 nm.
+
3+
2+
2+
2+
2+
2+
2+
2+
2+
2+
2+
ZH Ag Fe Hg Ca Cu
Co Ni
Cd Pb
Zn Cr Mg
ZH and other metal ions
＋
Figure 3 Fluorescence spectra of ZH and ZH-Ag in the
presence of 10 equiv. of various metal ions in DMSO/H O (V/V,
2
1
∶1; buffered with HEPES, pH＝7.20) solutions.
ZH + metal ions
0
0
0
0
0
0
0
0
.7
.6
.5
.4
.3
.2
.1
.0
+
ZH + Ag + metal ions
Figure 6 UV-vis spectra of ZH in the presence of different
＋
2
concentrations of Ag in DMSO/H O (V/V, 1∶1; buffered with
HEPES, pH＝7.20) solutions. Inset: a plot of absorbance de-
＋
pending on the concentration of Ag in the range from 0 to 14.2
equivalents.
＋
For better understanding the Ag binding properties
1
of ZH, H NMR titration, and ESI-MS methods were
+
3+
2+
2+
2+
2+
2+
2+
2+
2+
2+
2+
ZH Ag Fe
Hg Ca Cu
Co
Ni Cd Pb Zn Cr Mg
used to illustrate the characteristic structural changes
ZH and metal ions
＋
occurring upon interaction with Ag . As shown in Fig-
ure 7, the H NMR chemical shifts of ZH show two
strong peaks at δ 13.45 and 8.6, which could be as-
＋
1
Figure 4 UV-vis spectra of ZH and ZH-Ag in the presence of
0 equiv. of various metal ions in DMSO/H O (V/V, 1∶1; buff-
ered with HEPES, pH＝7.20) solutions.
1
2
signed to the N-H (H ) proton and Ar-H (H ) proton
b
a
＋
respectively. After addition of 0.1 equivalent of Ag , the
We also plotted fluorescence and UV-vis absorbance
N-H peak at δ 13.45 disappeared. At the same time, the
＋
against Ag concentration (Figures 5 and 6). In fluo-
a
Ar-H (H ) peak at δ 8.6 gradually decreased. From what
Chin. J. Chem. 2017, XX, 1—6
© 2017 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
3

Wei et al.
FULL PAPER
we have discussed above, we can safely draw a conclu-
sion that Ag coordinates with sensor ZH through py-
π-π stacking interactions. Importantly, hydrogen bond-
＋
[11]
ing played a crucial role in this perfect cooperation.
＋
razine group, which shields H
decreased.
a
proton because its peak
With the addition of Ag , the perfect cooperation was
destroyed which caused the optical properties to change
(
Figure 11).
＋
Figure 9 The SEM images of (a) ZH and (b) ZH-Ag .
3
2
2
1
1
000
500
000
500
000
+
1
7.19
ZH-Ag
ZH
Figure 7 Partial H NMR spectra of free ZH and ZH in the
＋
presence of varying amounts of Ag .
3.52
3
.17
1
8.64
5
00
0
1
6.64
1
4.29917346 25.99706174 37.69495003 49.39283831
o
2
( )
＋
Figure 10 XRD diagrams of ZH and ZH-Ag .
p-p
p-p
N
NH
HN
N
N
N
N
N
N
self-assemble
N
N
N
N
NH
N
NH
＋
Figure 8 ESI-MS spectrum of ZH-Ag .
A key to explore mechanism was the assembling
＋
structure of ZH and ZH-Ag . The SEM images of ZH
showed regular spindle shape (Figure 9a). As shown in
Figure 9b, upon addition of Ag , the regular spindle
＋
N
shape of ZH changed to an irregular cluster structure.
From their X-ray diffraction (XRD) (Figure 10), we
obtained a d-spacing of 3.51 Å by 2θ＝25.33°, suggest-
ing that π-π stacking of intermolecular may exist. Un-
Ag+
N
N
N
Ag+
I-
N
expectedly, the π-π stacking was destroyed after adding
Ag . Based on all of above tests, we rationally inferred
＋
N
N
the same groups repelled from each other due to the
electrostatic repulsion interactions. The formation of
spindle shapes must relate to the perfect cooperation
between the electrostatic repulsion interactions and the
N
Figure 11 Proposed sensing mechanism of the sensor ZH for
the detection of silver ion.
4
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＋
Fluorescent and Colorimetric Sensor for Ag
＋
Ag . The distinct color changes under day light and
The reversibility of the sensor function was tested by
–
addition of I to the silver-sensor complex. Upon the
rapid fluorescence extinction can be detected by naked
–
＋
addition of I , the optical fluorescence intensity gradu-
eyes. The detection of Ag by using ZH is found to be
–
＋
ally increased. The addition of I to the ZH-Ag
totally free of interference from any other ions, and the
mechanism of the supramolecular self-assembly was
investigated by XRD and SEM. Moreover, this sensor
can be used multiple times during the detection process.
The experiment proved that this sensor can be used
above 5 times. Taking advantage of the mechanism of
the supramolecular self-assembly and the successful
application to paper testing, we believe that the sensor
complex shows that the process could be repeated sev-
eral times (Figure S9). Therefore, sensor ZH could be
considered as a good ON-OFF fluorescent switch.
The practical application of sensor is particularly
important for its development and research, so we stud-
ied pH scope for ZH application and made comparison
test strips. As shown in Figure 12, ZH can be used in a
wide range of 7 to 13. Test strips were prepared by im-
mersing filter paper into a DMSO solution of ZH (2×
ZH has the potential applications in environment and
＋
physiological systems for Ag detection.
–
5
1
0
mol/L) and then drying them in air. The test strips
＋
Acknowledgement
containing ZH were utilized to sense Ag . As shown in
＋
Figure 13 and Figure S5, when Ag was added on the
This work was supported by the National Natural
Science Foundation of China (Nos. 21161018,
test kits, the obvious fluorescence quenching and color
changing were observed. Therefore, the test strips could
2
1262032, 21574104), the Program for Chang Jiang
＋
conveniently detect Ag in solution.
Scholars and Innovative Research Team in University of
Ministry of Education of China (No. IRT1177).
4
3
3
2
2
1
1
00
50
00
50
00
50
00
ZH
References
+
ZH+Ag
[
1] (a) Li, X.; Chen, J.; Wang, E. Chin. J. Chem. 2014, 32, 429; (b)
Zhang, Z.; Wang, H.; Zhang, H.; Liu, Y. Chin. J. Chem. 2013, 31,
5
98; (c) Hong, M. M.; Liu, A. F.; Xu, Y.; Xu, D. M. Chin. Chem.
Lett. 2016, 27, 989; (d) Lin, Q.; Yang, Q.; Sun, B.; Wei, T.; Zhang, Y.
Chin. J. Chem. 2014, 32, 1255; (e) Huang, Y. Z.; Lei, L. Q; Zhen, C.;
Wei, B.; Zhao, Z. J.; Qin, A. J.; Hu, R. R.; Tang, B. Z. Acta Chim.
Sinica 2016, 74, 885; (f) Tu, T.; Fang, W.; Sun, Z. Adv. Mater. 2013,
5
0
0
2
5
5, 5304; (g) Fang, W.; Liu, X.; Lu, Z.; Tu, T. Chem. Commun. 2014,
0, 3313; (h) Tu, T.; Fang, W.; Bao, X.; Li, X.; Dötz, K. H. Angew.
2
4
6
8
10
12
Chem., Int. Ed. 2011, 50, 6601; (i) Fang, W.; Liu, C.; Chen, J.; Lu,
Z.; Li, Z. M.; Bao, X.; Tu, T. Chem. Commun. 2015, 51, 4267.
pH
[
[
2] (a) Su, J.; Huang, S. S.; He, S.; Zeng, X. S. Chem. Res. Chin. Univ.
Figure 12 The pH response of ZH in the DMSO/H O (V/V, 1∶
2
2
016, 32, 20; (b) Yu, C.; Zhang, J.; Ding, M.; Chen, L. Anal. Meth-
1
; buffered with HEPES) solution.
ods 2012, 4, 342; (c) Lou, T.; Chen, Z.; Wang, Y.; Chen, L. ACS
Appl. Mater. Interfaces 2011, 3, 1568; (d) Chen, L.; Zhao, Q.; Zhang,
X. Y.; Tao, G. H. Chin. Chem. Lett. 2014, 25, 261.
3] (a) Zhiani, R.; Ghanei-Motlag, M.; Razavipanah, I. G. J. Molecular
Liquids 2016, 219, 554; (b) Yang, Y. Q.; Zhang, S. A.; Kang, M. M.;
He, L. H.; Zhao, J. H.; Zhang, H. Z.; Zhang, Z. H. Anal. Biochem.
2
015, 490, 7.
[
[
4] Hu, M.; Fan, J.; Cao, J.; Song, K.; Zhang, H.; Sun, S.; Peng, X. An-
alyst 2012, 137, 2107.
5] (a) Kazemi, E.; Shabani, A. H.; Dadfarnia, S. Microchim. Acta 2015,
1
82, 1025; (b) Motlagh, M. G.; Fayazi, M.; Taher, M. A.; Jalalinejad,
A. Chem. Eng. J. 2016, 290, 53; (c) Ndung’u, K.; Ranville, M. A.;
Franks, R. P.; Flegal, A. R. Mar. Chem. 2006, 98, 109; (d) Shamsi-
pur, M.; Hashemi, O. R.; Niasari, M. S. Sep. Sci. Technol. 2007, 42,
5
67.
6] (a) Jones, P.; Beere, H. G. Anal. Proc. Incl. Anal. Commun. 1995, 3,
69; (b) Kim, S. K.; Lee, S. H.; Lee, J. Y.; Lee, J. Y.; Bartsch, R. A.;
[
[
1
Figure 13 Photographs of ZH and the mixture of ZH and dif-
ferent cations on the test papers in the DMSO/H O (V/V, 1∶1;
Kim, J. S. J. Am. Chem. Soc. 2004, 126, 16499; (c) Kaur, M.; Cho,
M. J.; Choi, D. H. Dyes Pigments 2016, 125, 1.
2
7] (a) Wang, S. L.; Wu, F. Y.; Cheng, C.; Zhang, G.; Liu, Y. P.; Jiang, B.;
Shi, F.; Tu, S. J. ACS Comb. Sci. 2011, 13, 135; (b) Bryant, J. J.;
Zhang, Y. X.; Lindner, B. D.; Davey, E. A.; Appleton, A. L.; Qian, X.
H.; Bunz, U. H. F. J. Org. Chem. 2012, 77, 7479; (c) Engelhart, J. U.;
Paulus, F.; Schaffroth, M.; Vasilenko, V.; Tverskoy, O.; Rominger, F.;
Bunz, U. H. F. J. Org. Chem. 2016, 81, 1198; (d) Zhang, H. M.; Wu,
Y. C.; You, J. Y.; Cao, L.; Ding, S.; Jiang, K.; Wang, C. Y. Chin. J.
Org. Chem. 2016, 36, 2559.
buffered with HEPES, pH＝7.20) solution with irradiation at 365
nm.
Conclusions
In conclusion, we have presented a low-cost and ef-
ficient phenazine-based sensor with high sensitivity for
Chin. J. Chem. 2017, XX, 1—6
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www.cjc.wiley-vch.de
5

Wei et al.
FULL PAPER
[
8] (a) Yu, L. T.; Zhou, X. G.; Wu, D.; Xiang, H. F. J. Organomet. Chem.
012, 705, 75; (b) Miller, R. D.; Chandross, E. Chem. Rev. 2010,
10, 1; (c) Rabaey, K.; Boon, N.; Höfte, M.; Verstraete, W. Environ.
[9] (a) Lin, Q.; Sun, B.; Yang, Q. P.; Fu, Y. P.; Zhu, X.; Wei, T. B.;
Zhang, Y. M. Chem. Eur. J. 2014, 20, 11457; (b) Wu, G. Y.; Shi, B.
B.; Lin, Q.; Li, H.; Zhang, Y. M.; Yao, H.; Wei, T. B. RSC Adv. 2015,
5, 4958; (c) Shi, B. B.; Zhang, P.; Wei, T. B.; Yao, H.; Lin, Q.; Zhang,
Y. M. Chem. Commun. 2013, 49, 7812.
[10] Analytical Methods Committee, Analyst 1987, 112, 199.
[11] Mosali, V. S.; Bowmaker, S. G. A.; Gerard, M.; Kilmartin, P. A.;
Sejdic, J. T.; Zujovicb, Z. D. Polym. Int. 2015, 64, 1135.
2
1
Sci. Technol. 2005, 39, 3401; (d) Koepf, P. M.; Lee, S. H.; Brennan,
B. J.; Hernández, D. D. M.; Batista, V. S.; Brudvig, G. W.; Crabtree,
R. H. J. Org. Chem. 2015, 80, 9881; (e) Wang, P.; Klein, C.; Baker,
R. H.; Zakeeruddin, S. M.; Grätzel, M. J. Am. Chem. Soc. 2005, 127,
8
08.
(Zhao, X.)
6
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