A highly selective colorimetric sensor for Cu2+ based on phenolic group biscarbonyl hydrazone

Article abstract of DOI:10.1002/cjoc.201200741

A novel copper selective sensor 2 based on hydrazide and salicylaldehyde has been designed and prepared. Sensor 2 behaves a single selectivity and sensitivity in the recognition for Cu²⁺ over other metal ions such as Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Zn ²⁺, Pb²⁺, Cd²⁺, Ni²⁺, Co ²⁺, Cr³⁺ and Mg²⁺in DMSO. The distinct color change and the rapid changement of fluorescence emission provide naked-eyes detection for Cu²⁺. The UV-vis data indicate that 1:2 stoichiometry complex is formed by sensor 2 and Cu²⁺. The association constant K_s was 3.51×10⁴ mol^-1·L. The detection limitation of Cu²⁺with the sensor 2 was 2.2×10 ^-7 mol·L^-1. The sensing of Cu²⁺ by this sensor was found to be reversible, with the Cu²⁺-induced color being lost upon addition of EDTA. Copyright

Full text of DOI:10.1002/cjoc.201200741

FULL PAPER
DOI: 10.1002/cjoc.201200741
＋
A Highly Selective Colorimetric Sensor for Cu2 Based on
Phenolic Group Biscarbonyl Hydrazone
Junjian Li, Ying Guo, Hong Yao, Qi Lin, Yongqiang Xie, Taibao Wei,* and Youming Zhang*
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
A novel copper selective sensor 2 based on hydrazide and salicylaldehyde has been designed and prepared.
＋
＋
,
Sensor 2 behaves a single selectivity and sensitivity in the recognition for Cu2 over other metal ions such as Fe3
Hg2 , Ag＋, Ca2 , Zn2 , Pb2 , Cd2 , Ni2 , Co2 , Cr3 and Mg2 in DMSO. The distinct color change and the rapid
＋
＋
＋
＋
＋
＋
＋
＋
＋
changement of fluorescence emission provide naked-eyes detection for Cu2＋. The UV-vis data indicate that 1∶2
＋
stoichiometry complex is formed by sensor 2 and Cu2 . The association constant Ks was 3.51×104 mol−1•L. The
＋
＋
detection limitation of Cu2 with the sensor 2 was 2.2×10−7 mol•L−1. The sensing of Cu2 by this sensor was
found to be reversible, with the Cu2＋-induced color being lost upon addition of EDTA.
Keywords copper ion, colorimetric sensor, biscarbonyl hydrazone, single selectivity
Introduction
are highly demanded.[19-22]
Herein, as one part of our research interest in supra-
molecular recognitions,[23-27] we attempted to design an
easily synthesized, highly selective, and sensitive sen-
In recent years, the design and exploration of chemo-
sensors probes for the detection of transition metal ions
have been received extensive attention because chemo-
sensors have several advantages such as high selectivity,
sensitivity, and real-time monitoring over other meth-
ods.[1,2] Among transition metal ions, copper is one of
the important elements in humans, and is present at low
levels in a variety of cells and tissues with the highest
concentration in the liver.[3,4] Copper is utilized in sev-
eral physiological responses and copper containing pro-
teins are useful as redox catalysts in biological proc-
esses such as electron transfer or oxidation of various
organic substrates.[5,6] However, chronic copper over-
load or exposure to excess copper by accidents and en-
vironmental contamination can lead to oxidative dam-
age.[7] Therefore, the rational design and synthesis of
efficient sensors to selectively recognize copper cation
is an important field of supramolecular chemistry.[8-13]
Although previous work developed a wide variety of
＋
sors for Cu2 . We have designed and synthesized sen-
sors 1, 2 and 3 which bear phenol and carbonyl hydra-
＋
zone groups. Our strategies for designing of Cu2
colorimetric sensors are as follows: firstly, in order to
allow the coordination capacity required to coordinate a
copper ion, we introduced phenol groups into the same
sensor molecule. Secondly, to achieve “naked-eye”
＋
recognition upon binding of Cu2 , we introduced nitro-
phenyl groups as a chromophore. Thirdly, a carbonyl
hydrazone structure was used to significantly enhance
intramolecular charge transfer. Interestingly, sensor 2
＋
could “naked-eye” recognize Cu2 with high selectivity
and sensitivity in DMSO solution; other cations such as
＋
＋
＋
＋
＋
＋
＋
＋
Fe3 , Hg2 , Ag＋, Ca2 , Zn2 , Pb2 , Cd2 , Ni2 , Co2 ,
＋
＋
Cr3 and Mg2 could not cause any interference.
chemical[14,15] and physical[16,17] sensors for the detec-
Experimental
＋
tion of Cu2 , it is still a challenge to design the ion sen-
Apparatus and reagents
sors with high selectivity and sensitivity in the context
of interference from coexisting metal ions. Moreover,
most of these methods require expensive equipment and
involve time-consuming and laborious procedures that
can be carried out only by trained professionals.[18] This
1H NMR spectra were recorded on a Mercury-
1
400BB spectrometer at 400 MHz. H chemical shifts
were reported in ppm downfield from tetramethylsilane
(TMS, δ scale with solvent resonances as internal stan-
dards). UV-vis spectra were recorded on a Shimadzu
UV-2550 spectrometer. Fluorescent spectra were re-
corded on a Shimadzu RF-5301 spectrometer. Melting
will significantly restrict the practical applications of
＋
these Cu2 sensors. For simplicity, convenience and
＋
low cost, the easily prepared Cu2 colorimetric sensors
*
E-mail: weitaibao@126.com (Prof. T. B. Wei); zhangnwnu@126.com (Prof. Y. M. Zhang)
Received July 18, 2012; accepted October 17, 2012; published online December 11, 2012.
Chin. J. Chem. 2013, 31, 271—276
© 2013 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
271

Li et al.
FULL PAPER
1
points were measured on an X-4 digital melting-point
apparatus (uncorrected). Infrared spectra were per-
formed on a Digilab FTS-3000 FT-IR spectrophotome-
ter. Mass spectra were measured with a Bruker Dalton-
ics Esquire 6000. All reagents used were of analytical
grade.
2: Yield 84%, m.p.＞300 ℃; H NMR (DMSO-d6,
400 MHz) δ: 12.24 (s, 2H, Ar-OH), 11.26 (s, 2H, NH),
10.30 (s, 1H, CH), 8.68 (s, 2H, ＝CH), 6.92－7.96 (m,
11H, ArH); 13C NMR (DMSO-d6, 100 MHz) δ: 116.479,
117.530, 117.934, 118.757, 119.451, 129.488, 131.576,
134.632, 148.509, 157.502. 162.349, 162.395; IR (KBr)
ν: 1665.25, 1622.88, 3317.56 cm−1. Anal. calcd for
C22H18N4O5: C 63.37, H 4.54, N 13.20; found C 63.15,
H 4.34, N 13.39. MS calcd for C22H18N4O5＋H 419.4,
found 419.3.
Synthesis of sensors 1, 2 and 3
The syntheses of sensors 1, 2 and 3 are outlined in
Scheme 1. The compound 4 (5-hydroxy-1,3-benzenedi-
carboxylic dihydrazide) was prepared according to the
literature reported.[28] Intermediate 5-hydroxy-1,3-ben-
zenedicarboxylic dihydrazide (0.01 mol) and benzalde-
hyde derivatives (0.01 mol) were mixed in absolute
ethanol solutions (50 mL) with hydrochloric acid as a
catalyst. Then, the resulting solution was stirred under
reflux conditions for 8 h at 80 ℃. After cooling, and
removing the solvent, the residue was purified by re-
crystallization from DMF-EtOH to get 1, 2 and 3.
1
3: Yield 78%, m.p.＞300 ℃; H NMR (DMSO-d6,
400 MHz) δ: 12.30 (s, 2H, Ar-OH), 12.22 (s, 2H, NH),
10.21 (s, 1H, CH), 8.69 (s, 2H, ＝CH), 7.03－8.53 (m,
9H, ArH); 13C NMR (DMSO-d6, 100 MHz) δ: 117.172,
117.697, 118.132, 120.144, 123.635, 126.752, 134.540,
139.997, 144.524, 157.715, 162.425, 162.623; IR (KBr)
ν: 1664.17, 1658.92, 3361.72 cm−1. Anal. calcd for
C22H16N6O9: C 51.77, H 3.24, N 16.40; found C 51.97,
H 3.17, N 16.53. MS calcd for C22H16N6O9＋H 509.4,
found 509.2.
1: Yield 76%, m.p. 297 － 299 ℃ ; 1H NMR
(DMSO-d6, 400 MHz) δ: 11.90 (s, 2H, NH), 10.16 (s,
1H, Ar-OH), 8.40 (s, 2H, ＝CH), 7.38－7.87 (m, 13H,
ArH); 13C NMR (DMSO-d6, 100 MHz) δ: 117.805,
127.247, 128.962, 130.288, 134.319, 135.180, 148.212,
157.987, 162.448, 162.768; IR (KBr) ν: 1654.17,
1649.38, 3185.72 cm−1. Anal. calcd for C22H18N4O3: C
68.51, H 4.53, N 14.82; found C 68.38, H 4.70, N 14.50;
MS calcd for C22H18N4O3＋H 387.4, found 387.4.
General spectroscopic methods
All UV-vis spectroscopy and fluorescent spectros-
copy were carried out just after the addition of perchlo-
rate metal salts in DMSO solution, while keeping the
ligand concentration constant (2.0×10−5 mol/L) on a
Shimadzu UV-2550 spectrometer and a Shimadzu
RF-5301 spectrometer. The solutions of metal ions were
Scheme 1 Synthetic procedures for sensors 1, 2 and 3
OH
O
O
HN
NH
N
N
CH HC
1
CHO
OH
OH
OH
O
O
OH
CHO
.
NH2NH2 H2O
HN
NH
N
N
O
O
O
O
MeOH
CH HC
OCH3
OCH3
NHNH2
NHNH2
4
OH HO
2
O2N
OH
OH
CHO
O
O
HN
NH
N
N
O2N
CH HC
NO2
OH HO
3
272
www.cjc.wiley-vch.de
© 2013 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2013, 31, 271—276

＋
A Highly Selective Colorimetric Sensor for Cu2 Based on Phenolic Group Biscarbonyl Hydrazone
＋
＋
prepared from the perchlorate salts of Fe3 , Hg2 , Ag＋,
upon addition of any metal, indicating that sensor 1 was
not a good sensor for these metals.
＋
＋
＋
＋
＋
＋
＋
＋
Ca2 , Cu2 , Zn2 , Pb2 , Cd2 , Ni2 , Co2 , Cr3 and
＋
Mg2 .
To further exploit the utility of sensor 2 as ion-se-
＋
lective sensor for Cu2 , competitive experiments were
＋
carried out in the presence of 5.0 equiv. of Cu2 and
Results and Discussion
various metal ions in the DMSO. As shown in Figure 3,
sensor 2 (2.0×10−5 mol/L) shows an obvious color
The colorimetric sensing abilities were primely in-
＋
vestigated by adding various metal ions such as Fe3 ,
change from colorless to yellow green upon addition of
＋
＋
＋
＋
＋
＋
＋
＋
Hg2 , Ag＋, Ca2 , Cu2 , Zn2 , Pb2 , Cd2 , Ni2 , Co2 ,
＋
5 equiv. of Cu2 in DMSO solution; the peak at 333 nm
＋
＋
Cr3 and Mg2 to DMSO solutions of sensors 1, 2 and 3,
disappeared in the UV-vis spectrum and a new signal
appeared at 400 nm. On the other hand, a variety of
＋
respectively. When adding 5 equiv. of Cu2 to the
＋
＋
＋
＋
other metal ions, such as Fe3 , Hg2 , Ag＋, Ca2 , Zn2 ,
DMSO solution of sensors 1, 2 and 3, 2 and 3 responded
with dramatic color changes from colorless to yellow-
green. In the corresponding UV-vis spectrum, a strong
and broad absorption band from 340 to 400 nm was ob-
served for sensors 2 and 3. To validate the selectivity of
＋
＋
＋
＋
＋
＋
Pb2 , Cd2 , Ni2 , Co2 , Cr3 and Mg2 , did not cause
such a significant change, indicating that the sensor
＋
2-Cu2 was hardly affected by these coexistent cations.
Accordingly these results suggested that sensor 2 still
＋
＋
sensor 2, the same tests were applied using Fe3 , Hg2 ,
＋
displayed an excellent selectivity toward Cu2 .
Ag＋, Ca2 , Zn2 , Pb2 , Cd2 , Ni2 , Co2 , Cr3 and
＋
＋
＋
＋
＋
＋
＋
＋
Mg2 metal ions, and none of these ions induced any
significant changes in the UV-vis spectrum of sensor 2.
Meanwhile, the absorbance changes of sensor 1 with
different metal ions are also shown in Figure 1a. No
obvious changes were observed in the UV-vis spectrum
Figure 2 (a) Solutions of sensor 2 upon addition of different
metal ions. (b) Absorption changes of sensor 2 (c＝2.0×10−5
mol/L) in DMSO upon addition of 5 equiv. of different metal
perchlorate salts.
＋
The stoichiometry between the sensor 2 and Cu2
was determined by Job’s plot. As expected, when the
molar fraction of sensor 2 was 0.35, the absorbance
value approached a maximum, which demonstrated the
＋
formation of 1∶2 complex between sensor 2 and Cu2 .
In order to estimate the specific properties for selec-
＋
tive recognition of Cu2 and colorimetric changes as-
＋
sociated with the sensor 2, the sensor 2 toward Cu2
was studied by UV-vis absorption spectra titration ex-
periments. Along with the increasing of concentration of
＋
Cu2 , a significant decreasing of the UV-vis absorbance
at 332 nm and a new band centered at 400 nm were ob-
served. Such a red shift led to the solution color chang-
ing from colorless to yellow green. On the other hand,
Figure 1 Absorption changes of sensors 1 and 3 (c＝2.0×10−5
mol/L) in DMSO upon addition of 5 equiv. of different metal
perchlorate salts.
Chin. J. Chem. 2013, 31, 271—276
© 2013 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
273

Li et al.
FULL PAPER
F − F
0 ＝lg K＋nlg[M]
Fm − F
lg
(2)
Figure 3 Optical density of sensor 2 at 400 nm with addition of
＋
Cu2 in the presence of 5 equiv. of other metal ions.
Figure 5 Titration curves of sensor 2 in DMSO (c＝2.0×10−5
mol/L) upon addition of Cu2＋. Inset: A. Color change of sensor 2
in DMSO solution.
Similarly, the fluorescence spectra of sensor 2
＋
change significantly along with the increase of Cu2
concentration as shown in Figure 6. The intensity of the
fluorescence band centered at 500 nm of sensor 2 de-
＋
creased progressively along with the increase of Cu2
concentration, and it was quenched almost completely
＋
after the addition of 2 equiv. Cu2 .
＋
Figure 4 Job’s plot analysis for Cu2 versus receptor 2 in
DMSO solution measured at 400 nm.
two clear isosbestic points are observed at 340 and 380
＋
nm, which indicates the formation of 2-Cu2 complex.[29]
The binding constant K of the metal complex was de-
termined by Equation (1), assuming that the concentra-
tion of free metal is about equal to its total concentration
([M]≈[M]t), where F0, F and Fm are the corrected
emission intensities of the complex at initial, interval,
and the final states at which the complex was fully
formed upon addition of metal ion, respectively. The
binding constant K was determined from the plot of the
linear regression of lg[(F−F0)/(Fm−3F)] vs. lg[M] in
Equation (2), derived from Equation (1), to obtain the
Figure 6 Fluorescent intensity (λex＝420 nm) changes of sensor
＋
2 in DMSO upon the additio of Cu2 ions. Inset: Fuorescent
change of sensor 2 under 365 nm lamp excitation.
intercept as lg K and the slope as n.[30] Thus, the asso-
＋
ciation constant K of the sensor 2 toward Cu2 was
The reversibility of the chemosensor function was
calculated as 3.51×104 mol−1•L. Furthermore, with the
tested by titration of the copper-sensor complex with
＋
EDTA, which is a well-known chelator of Cu2 . Addi-
＋
probe concentrations employed in our studies, interac-
tion of EDTA into a solution of sensor 2-Cu2 complex
＋
tions of sensor 2 with Cu2 could be detected down to
at least concentrations of 2.2×10−7 mol/L in DMSO,[31]
induced the opposite trend in the absorption spectra to
＋
that observed on titration with Cu2 . Upon addition of 2
showing that this sensor could potentially be used as a
＋
probe for monitoring Cu2 levels in physiological and
equiv. of EDTA, the optical absorbance intensity re-
turned to the levels observed for the free sensor 2 (Fig-
environmental systems.
ure 7). This shows that the process of titrating sensor 2
＋
with Cu2 is reversible, and that sensor 2 could there-
F − F0 [C]
Fm − F [D]
＝
＝K[M]n
(1)
fore be used as an off-on switch chemosensor.
274
www.cjc.wiley-vch.de
© 2013 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2013, 31, 271—276

＋
A Highly Selective Colorimetric Sensor for Cu2 Based on Phenolic Group Biscarbonyl Hydrazone
＋
Scheme 2 Proposed complexation mechanism of sensor 2 with Cu2
＋
the detection limit of sensor 2 toward Cu2 is 2.2 ×
10−7 mol/L, which indicated that the sensor 2 could po-
＋
tentially be useful as a probe for monitoring Cu2 lev-
els in physiological and environmental systems. In addi-
＋
tion, the sensor also displayed a Cu2 -induced off-on
type of signaling pattern (tested by titration of the cop-
per-sensor complex with EDTA), which means that the
sensor could be used as a supramolecular switching sys-
tem.
Acknowledgement
This work was supported by the National Natural
Science Foundation of China (NSFC) (Nos. 21064006
and 21161018), the Natural Science Foundation of
Gansu Province (1010RJZA018) and the Program for
Changjian Scholars and Innovative Research Team in
University of Minisry of Education of China (IRT1177).
＋
Figure 7 UV-vis spectra of sensor 2-Cu2 (c＝2.0×10−5
mol/L) in DMSO solution upon addition of EDTA. Inset: Color
＋
changes of sensor 2-Cu2 upon the addition of EDTA.
References
[1] de Silva, A. P.; Gunaratne, H. Q. N.; Gunnlaugsson, T.; Huxley, A. J.
M.; McCoy, C. P.; Rademacher, J. T.; Rice, T. E. Chem. Rev. 1997,
97, 1515.
[2] Chen, X. Q.; Wang, F.; Yoon, J. Chem. Rev. 2012, 112, 1910.
[3] Wu, Y. Y.; Wang, X.; Liang, R. L. Acta Scientlae Circumstantla
1998, 18, 407.
[4] Wang, X. C.; Liu, X. R.; Yang, Y. L.; Li, Q. Spectrosc. Spect. Anal.
2010, 30, 2693.
[5] Yu, M. C.; Jin, Y. Q.; Qi, X.; Bao, L. J.; Qian, Z. S.; Zhu, C. Q.
Chin. J. Chem., 2010, 28, 1165.
By mass spectral analyses, the ion peaks were de-
tected at m/z 419.3, which are corresponding to [2＋H]＋.
The peak at m/z 699.0 also demonstrated the presence of
[2 ＋ Cu-H] ＋ . Thus, in accordance with the 1 ∶ 2
stoichiometry, sensors are most likely to chelate with
metal ions via its carbonyl O, imino N, and hydroxyl O
atoms (Scheme 2).
Conclusions
[6] Que, E. L.; Domaille, D. W.; Chang, C. J. Chem. Rev. 2008, 108,
1517.
[7] Chen, T. B.; Huang, Q. F.; Gao, D.; Wu, J. F. Acta Scientlae Cir-
cumstantlae 2003, 23, 561.
A new double carbonyl hydrazone derivative sensor
2 was synthesized and characterized. Sensor 2 exhibits
reversible and highly selective and sensitive recognition
[8] Sheng, R. L.; Wang, P. F.; Gao, Y. H.; Wu, Y.; Liu, W. M. Org. Lett.
2008, 10, 5015.
[9] Hu, M. B.; Li, H. X.; Chen, L. S.; Zhang, H. B.; Dong, C. Chin. J.
Chem. 2009, 27, 513.
[10] Dai, H. L.; Xu, H. Chin. J. Chem. 2012, 30, 267.
[11] Li, L. B.; Ji, S. J.; Liu, Y. Chin. J. Chem. 2008, 26, 979.
[12] Chereddy, N. R.; Thennarasu, S. Dyes Pigm. 2011, 91, 378.
[13] Zhou, Y. M.; Zhang, J. L.; Zhou, H.; Zhang, Q. Y.; Ma, T. S.; Niu, J.
Y. J. Lumin. 2012, 132, 1837.
[14] Ando, S.; Koide, K. J. Am. Chem. Soc. 2011, 133, 2556.
[15] Santra, M.; Roy, B.; Ahn, K. H. Org. Lett. 2011, 13, 3422.
[16] Lin, L. Y.; Chang, L. F.; Jiang, S. J. J. Agric. Food Chem. 2008, 56,
6868.
＋
toward Cu2 over other metal ions. Upon addition of
＋
Cu2 , sensor 2 exhibits remarkably enhanced absorb-
ance intensity and color change from colorless to yellow
green in DMSO solution. And the fluorescence spectra
of sensor 2 change significantly along with the concen-
＋
tration increase of Cu2 and it was quenched almost
＋
completely after the addition of 2 equiv. Cu2 . The re-
searches of recognition mechanism indicated that sensor
＋
2 recognize Cu2 by forming a stable 1∶2 sensor 2-
＋
Cu2 complex. The coexisting of other cations could
＋
not interfere the Cu2 recognition process, moreover,
Chin. J. Chem. 2013, 31, 271—276
© 2013 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.cjc.wiley-vch.de
275

Li et al.
FULL PAPER
[17] Dolan, S. P.; Nortrup, D. A.; Bolger, P. M.; Capar, S. G. J. Agric.
Food Chem. 2003, 51, 1307.
L. Sens. Actuators B 2009, 137, 447.
[25] Zhang, Y. M.; Cao, C.; Wei, W.; Wei, T. B. Chin. J. Chem. 2007, 25,
[18] Tang, L.; Li, F.; Liu, M.; Nandhakumar, R. Spectrochim. Acta A
2011, 78, 1168.
[19] Zhang, J.; Yu, C. W.; Qian, S. Y.; Lu, G.; Chen, J. L. Dyes Pigm.
2012, 92, 1370.
[20] Zhang, D. Q.; Jin, W. S. Spectrochim. Acta A 2012, 90, 35.
[21] Xu, M.; Liu, H. Y.; Ma, Z. R.; Bai, D. C.; Zeng, Z. Z. Dyes Pigm.
2011, 90, 265.
709.
[26] Liu, M. X.; Wei, T. B.; Lin, Q.; Zhang, Y. M. Spectrochim. Acta A
2011, 79, 1837.
[27] Zhang, Y. M.; Xu, W. X.; Yao, H.; Wei, T. B. Chin. J. Chem. 2006,
24, 1406.
[28] Long, D. Q.; Chen, S. S.; Li, D. J. Jiangxi Normal Univ. 2006, 30,
372.
[22] Yang, H.; Zhu, Y. C.; Li, L. T.; Zhou, Z. G.; Yang, S. P. Inorg.
Chem. Commun. 2012, 16, 1.
[29] Valeur, B.; Pouget, J.; Bouson, J.; Kaschke, M.; Ernsting, N. P. J.
Phys. Chem. 1992, 96, 6545.
[23] Zhang, Y. M.; Lin, Q.; Wei, T. B.; Qin, X. P.; Li, Y. Chem. Com-
mun. 2009, 6074.
[30] Nguyen, D. M.; Frazer, A.; Rodriguez, L.; Belfield, K. D. Chem.
Mater. 2010, 22, 3472.
[24] Zhang, Y. M.; Lin, Q.; Wei, T. B.; Wang, D. D.; Yao, H.; Wang, Y.
[31] Committee, A. M. Analyst 1987, 112, 199.
(Zhao, X.)
276
www.cjc.wiley-vch.de
© 2013 SIOC, CAS, Shanghai, & WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Chin. J. Chem. 2013, 31, 271—276