An aggregation-induced emission based turn-on fluorescent chemodosimeter for the selective detection of Pb2+ ions

Article abstract of DOI:10.1039/c4ra09451d

An aggregation-induced emission (AIE) based turn-on fluorescent chemodosimeter for selective detection of Pb²⁺ions has been developed by making use of the strong affinity of lead ions for phosphate residues. The probe is a phosphate functionalized tetraphenylethylene derivative and the resulting lead-TPE complex has very low solubility in working solvent and triggers aggregation induced emission. The probe is highly efficient, cost-effective and shows a low detection limit of 10 ppb.

Full text of DOI:10.1039/c4ra09451d

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An aggregation-induced emission based “turn-on”
fluorescent chemodosimeter for the selective
detection of Pb2+ ions†
Cite this: RSC Adv., 2014, 4, 47076
a
a
a
Dipratn G. Khandare,‡ Hrishikesh Joshi,‡ Mainak Banerjee, Mahesh S. Majikb
Received 29th August 2014
Accepted 17th September 2014
*
a
*
and Amrita Chatterjee
DOI: 10.1039/c4ra09451d
www.rsc.org/advances
An aggregation-induced emission (AIE) based “turn-on” fluorescent It is therefore very important to develop lead sensors with high
chemodosimeter for selective detection of Pb2+ions has been devel- selectivity and sensitivity that are addressable at these
oped by making use of the strong affinity of lead ions for phosphate concentrations.
residues. The probe is a phosphate functionalized tetraphenylethylene
So far, a variety of techniques have been developed for
derivative and the resulting lead–TPE complex has very low solubility selective detection of Pb2+, which include potentiometry,5 X-ray
in working solvent and triggers aggregation induced emission. The uorescence Raman spectroscopy,6 isotope dilution mass
probe is highly efficient, cost-effective and shows a low detection limit spectrometry,7 electrochemical detection,8 nanoparticle based
of 10 ppb.
sensors,9 and many others.10 However, uorimetric sensing by
harnessing appropriate organic probes has drawn much more
attention because it is simple, sensitive, and cost-effective,11
and this technique is useful for detection of lead ions as well.12
However, traditional uorescent probes oen suffer from the
aggregation-caused quenching (ACQ) effect, when dispersed in
appropriate solvent or incorporated into solid matrices, result-
ing in huge drop in the performance and sensitivity.13 The ACQ
effect poses huge concern in real life applications, particularly,
in the in vivo detection of analytes.13 Recently, a group of
molecules, non-emissive in solution, have been found to lumi-
nescence intensively upon molecular aggregation, showing an
aggregation-induced emission (AIE) characteristic.14 Restriction
of intramolecular rotation is proposed as the main reason
behind this phenomenon. As their emission is turn-on in
nature, instead of quenching, AIE-active materials have found
enormous application in various elds15–18 such as efficient
sensitive chemo/biosensors,16,18a,b,d,g electroluminescent mate-
rials,17f,18e cell imaging,17a,d,e,18i optical devices18h,j etc. Among the
reported AIE active molecules, tetraphenylethylene (TPE), due
to its easy synthesis and also for simple functionalization
strategies, is one of the most studied luminophore for detection
of various analytes16 and other applications.17 However, to the
best of our knowledge, AIE property of these molecules has not
been exploited for the detection of Pb(II) ions. In the current
endeavor, as a part of our continued effort for the development
of uorescent sensors for biologically/environmentally impor-
tant analytes,16l,19 we planned to design a TPE-based uorescent
chemodosimeter for selective and sensitive detection of Pb2+
ions. The literature survey reveals that alkyl phosphates have a
very high affinity to Pb2+ ions and resulting lead phosphates
1. Introduction
Heavy metal ions that are used in industry pose a huge threat to
public health and the environment. Lead is an element with
pronounced industrial application and is extensively used in
storage batteries, alloys, lead wires, paints, high quality glasses,
for soldering of electronic devices, and in foundries.1 Lead is
recognized as one of the most hazardous metals to humans. It
accumulates in liver, kidney and in the central nervous system,
and interferes2 with a variety of physiological processes such as
biosynthesis of haemoglobin.2b Long exposures to high
concentration of lead can cause many health diseases such as
hemotoxic effects, reproductive dysfunction, gastrointestinal
tract alterations and nephropathies.2c In particular, Pb2+ is
dangerous for children, causing mental retardation.2,3 While US
Environmental Protection Agency (EPA) set safe threshold level
for lead as 15 ppb in drinking water, International Agency for
Research on Cancer (IARC) has much lower threshold (10 ppb).4
aDepartment of Chemistry, BITS Pilani, K. K. Birla Goa Campus, NH 17 B Bypass Road,
Zuarinagar, Goa 403726, India. E-mail: amrita@goa.bits-pilani.ac.in; mainak@goa.
bits-pilani.ac.in; Fax: +91-832-2557-033; Tel: +91-832-2580-320; +91-832-2580-347
bBio-organic Chemistry Laboratory, CSIR-National Institute of Oceanography, Dona-
Paula, Goa 403 004, India
† Electronic supplementary information (ESI) available: General information,
synthetic procedures and spectral data; spectra of probe 1 and intermediate 3;
real sample analysis. See DOI: 10.1039/c4ra09451d
‡ These authors contributed equally to this work.
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have very low solubility product (in the range of 10ꢀ10 to
10ꢀ50).9a Hence we envisioned, probe 1, a TPE monoester of
phosphoric acid (Fig. 1), can be used for the detection of Pb2+
ions in aqueous media as low solubility of corresponding TPE–
Pb complex will trigger aggregation of molecules in solution
and serve as AIE based sensor for lead ions.
Probe 1 was successfully synthesized following a three-step
procedure in high yield (Scheme 1) (see ESI†). First, TPE-OH (2)
was prepared adopting a reported synthetic route.20 The spectra
were in good agreement with the reported values. The
compound 2 was smoothly converted to diethyl-TPE-phosphate
(3) by reaction with diethylchlorophosphate followed by
deprotection of ethyl groups of 3 by trimethylsilyl iodide (TMSI)
to produce desired probe 1. Both the compounds were charac-
terized by 1H NMR, 13C NMR and ESI-MS. Attachment of
phosphate ester group in TPE-OH (2) to form 3 was indicated by
the presence of a methyl triplet at d 1.32 and a methylene
quartet at d 4.19 in 1H NMR. Similarly, the signals at 16.08 and
64.56 ppm were assigned as the carbons of the ethyl groups of
phosphate ester 3 in 13C NMR. More importantly, the expected
coupling of 31P and 13C nuclei was apparent in proton decou-
pled 13C NMR. It was observed that both the carbons of ethyl
groups and the aromatic carbon attached to phosphorous
appeared as doublets with coupling constant, J ¼ 6.8 Hz. The
NMR spectra clearly suggested the presence of a phosphate
moiety in compound 3. A base peak at m/z 485.0 (corresponds to
[M + H]+) in ESI-MS further supported the formation of the
desired product. The peaks of ethyl groups disappeared
completely in the NMR spectra of 1 indicating successful
deprotection. Otherwise, the NMR spectra of both of the
compounds have close resemblance. The presence of [M + H]+
peak at 428.9 as the base peak in ESI-MS was also in support of
the formation of probe 1. The sensing behaviour of the probe (1)
towards lead ions was investigated by conducting various
studies as described below.
Scheme 1 The synthetic route to probe 1.
over 95% water–THF. This indicates that probe 1 is AIE active
and therefore, useful for sensing studies.
To understand the sensing characteristic of probe 1 an
equivalence study was conducted. The uorescence intensities
of probe 1 (50 mM each) in 95% water–THF mixture upon
addition of Pb2+ ions (0 to 2 equiv.) was plotted (Fig. 3). It was
observed that the uorescence response from the system slowly
intensied upon gradual addition of lead ions. Presumably, the
sensing mechanism is based on two simple facts: (a) TPE
monoester of phosphoric acid, 1 has a strong affinity towards
Pb2+ ions and (b) the resulting lead phosphate is insoluble in
water or the working solvent system. Therefore, probe 1 readily
undergoes complexation with the available Pb2+ ions in the
solution. As soon as Pb(II)-complex is formed it goes out of the
working solvent system and forms a dispersed phase in which
further aggregation between the molecules of TPE–Pb complex
occurs. The aggregated form of TPE–Pb complex regains
planarity due to restricted rotational freedom triggering aggre-
gation induced emission. The AIE-based sensing mechanism of
probe 1 with Pb(II) ions is schematically represented in Fig. 4.
The solvent effect on the aggregation behaviour of probe 1
was examined using variable proportions of THF in water. As
expected, probe 1 was completely soluble and non-uorescent
in THF solution. Since the solubility of the compound is very
poor in water the uorescence intensity can be tuned by the
increment of water in the solvent mixture as the compound
starts aggregating at higher percentage of water. As shown in
Fig. 2, the uorescence intensity of probe 1 upon photo exci-
tation at 370 nm was negligible in THF. On continuous addition
of water into it, keeping the concentration of probe 1 xed at
50 mM, sharp increase in uorescence intensity was observed
Fig. 1 Structure of the TPE derivative (1) used for the sensing purpose Fig. 2 Fluorescence response of probe 1 (50 mM) in different solvent
of lead ions.
compositions of water–THF at 474 nm (lex 370 nm).
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Fig. 6 Maximum fluorescence response of a probe 1 (50 mM) in 95%
H2O–THF upon addition of different metal ions (50 mM each) (Al3+
Ba2+, Ca2+, Cd2+, Co2+, Fe2+, Fe3+, Mg2+, Ni2+, Pd2+, Sr2+, Ag+, Hg2+
Pb2+) and fluorescence response of probe 1 + Pb2+ + all metal ions.
,
,
Fig. 3 Fluorimetric response of probe 1 (50 mM) upon addition of Pb2+
(0–100 mM) in 95% water–THF [lex 370 nm; lem 474 nm]. Inset: (A) a
plot of the increment in fluorescence intensity against the concen-
tration of lead ions; (B) a picture of fluorescence change of 1 (50 mM)
upon addition of 1.0 equiv. of Pb2+ ion in 95% water–THF after 5 min.
addition of Pb2+ (50 mM, 1 equiv.) [mean diameter is 947 nm].
The above experimental facts strongly support spontaneous
formation of a TPE-based lead phosphate, which aggregates
further and shows uorescence by the AIE mechanism.
Aer successfully establishing the detection ability of the
probe towards Pb2+, the selectivity of the probe was assessed by
challenging it with several other environmentally relevant metal
ions. The experiment was conducted by adding 50 mM of various
metal ions like Ca2+, Fe2+, Mg2+, Ag+, Mn2+, Fe3+ etc., one at a
time, into a solution of probe 1 (50 mM) in 95% water–THF and
measuring the uorescence output of the system. As shown in
Fig. 6, the uorescence intensities of all the solutions other than
Pb2+ are very nominal. This study reveals that probe 1 is highly
selective to Pb2+ ions. Even the probe could detect Pb2+ ions
with similar efficiency in the presence of all metal ions (50 mM
each). Hence, none of the metal ions interferes in the sponta-
neous complexation of Pb2+ ions with probe 1.
Fig. 4 Sensing process of probe 1 based on AIE mechanism.
The extent of aggregation of probe 1 is directly dependent on
the concentration of lead ions and corresponding output holds
a linear relationship till the addition of 1 equiv. of Pb2+ (i.e.
50 mM) (Fig. 3, inset). At higher concentration of Pb2+ ions no
signicant change in uorescence intensity was observed indi-
cating full utilization of available probe molecules for complex
formation.
Limit of detection for any probe is an important character-
istics that needs to be dened. Under the optimal condition
mentioned above, the capability of our analytical tool for
quantitative detection of Pb(II) ions has been evaluated by
plotting relative uorescence intensity against concentration of
A DLS study was followed next to verify Pb2+ derived aggre-
gation of probe 1. DLS of probe 1 in 95% water–THF was
measured before and aer the addition of equimolar Pb2+ ions
(Fig. 5). From the particle size analysis the formation of nano-
scale aggregates was conrmed. Before addition of Pb2+, the
average particle size of around 60 nm was detected in the
solution of probe 1 (50 mM), which increases 16-fold aer the
Fig. 5 Particle size analysis of a probe 1 and reaction mixture after Fig.
7 The relative fluorescence response of probe 1 at lower
addition of 1.0 equiv. of Pb2+ in 95% H2O–THF.
concentration range of Pb(II) [concentration range: 50–250 nM].
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Pb(II) ions at lower concentration range (Fig. 7). A good linear
correlation (R2 ¼ 0.9967) was observed even at the nanomolar
concentration range (50–250 nM), from which the limit of
detection has been calculated as 10 ppb.
M.-R. Huang, Y.-B. Ding and X.-G. Li, ACS Comb. Sci., 2014,
16, 128.
6 E. V. Chuparina and T. S. Aisueva, Environ. Chem. Lett., 2007,
9, 19.
To demonstrate potential application of the probe as an
analytical tool for the detection of Pb2+ in various water bodies,
lead nitrate was spiked with water samples (for details, see
ESI†). Pre-spiked lead ion concentrations could be easily
detected by probe 1 in the contaminated water samples with as
high as 99–102% recovery.
7 K. E. Murphy and P. J. Paulsen, Fresenius' J. Anal. Chem.,
1995, 352, 203.
8 G. S. Reeder and W. R. Heineman, Sens. Actuators, B, 1998,
52, 58.
9 (a) S. K. Kim, S. Kim, E. J. Hong and M. S. Han, Bull. Korean
Chem. Soc., 2010, 31, 3806; (b) S.-P. Wu, I.-L. Lee and
Y.-M. Sung, RSC Adv., 2014, 4, 25251; (c) L. Beqa,
A. K. Singh, S. A. Khan, D. Senapati, S. R. Arumugam and
P. C. Ray, ACS Appl. Mater. Interfaces, 2011, 3, 668.
2. Conclusion
In conclusion, an AIE-based uorescence chemodosimeter has 10 (a) T. Lan, K. Furuya and Y. Lu, Chem. Commun., 2010, 46,
been successfully developed for the detection of Pb2+ ions. The
probe is a tetraphenylethylene phosphate monoester and was
designed keeping in mind the strong affinity of lead ions
towards phosphate residue. The probe spontaneously forms
water insoluble salt of lead ions and thereby, detects Pb2+ ions
in 95% water–THF by turn-on type uorescence response. The
3896; (b) I.-H. Chang, J. J. Tulock, J. Liu, W.-S. Kim,
D. M. Cannon Jr, Y. Lu, P. W. Bohn, J. V. Sweedler and
D. M. Cropek, Environ. Sci. Technol., 2005, 39, 3756; (c)
S. M. Taghdisia, S. S. Emranib, K. Tabrizianc,
M. Ramezanid, K. Abnouse and A. S. Emranif, Environ.
Toxicol. Pharmacol., 2014, 37, 1236.
probe is extremely sensitive and highly selective to Pb2+ ions. 11 (a) R. M. Duke, E. B. Veale, F. M. Pfeffer, P. E. Kruger and
The limit of detection of this probe is found to be 10 ppb. The
present method offers simple, cost-effective and efficient way
for detection of Pb2+ in aqueous media.
T. Gunnlaugsson, Chem. Soc. Rev., 2010, 39, 3936; (b)
M. J. Culzoni, A. M. de la Pena, A. Machuca,
H. C. Goicoechea and R. Babiano, Anal. Methods, 2013, 5,
30 and references cited therein; (c) H. N. Kim, W. X. Ren,
J. S. Kim and J. Yoon, Chem. Soc. Rev., 2012, 41, 3210; (d)
M. E. Jun, B. Roy and K. H. Ahn, Chem. Commun., 2011, 47,
7583; (e) F. Long, A. Zhu, H. Shi, H. Wang and J. Liu, Sci.
Rep., 2013, 3, 2308; (f) M. Li, H. Gou, I. Al-Ogaidi and
N. Wu, ACS Sustainable Chem. Eng., 2013, 1, 713; (g)
J. Chan, S. C. Dodanil and C. J. Chang, Nat. Chem., 2012, 4,
973; (h) X. Chen, G. Zhou, X. Peng and J. Yoon, Chem. Soc.
Rev., 2012, 41, 4610.
Acknowledgements
A. C. thanks DST (India) (project no. SR/FT/CS-092/2009) for
nancial support. M. B. is also thankful to CSIR (India) (project
no. 02(0075)/2012/EMR-II) for research fund. D. G. K. is thank-
ful to DST (India) for research fellowships. The authors thank-
fully acknowledge Prof. N. N. Ghosh of the same department for
DLS facility.
12 (a) K. Ghosh, T. Sarkar, A. Majumdar, S. K. Mandal and
A. R. Khuda-Bukhsh, Anal. Methods, 2014, 6, 2648; (b)
S. P. Goswami and R. Chakrabarty, Eur. J. Org. Chem.,
2010, 2010, 3791; (c) C.-Y. Li, Y. Zhou, Y. F. Li, X. F. Kong,
C. X. Zou and C. Weng, Anal. Chim. Acta, 2013, 774, 79; (d)
L. N. Neupane, J.-Y. Park, J. H. Park and K.-H. Lee, Org.
Lett., 2013, 15, 254.
Notes and references
1 N. Rifai, G. Cohen, M. Wolf, L. Cohen, C. Faser, J. Savory and
L. DePalma, Ther. Drug Monit., 1993, 15, 71 and references
cited therein.
2 (a) H. A. Godwin, Curr. Opin. Chem. Biol., 2001, 5, 223; (b)
J. R. Davis and S. L. Andelman, Arch. Environ. Health, 1967, 13 (a) J. B. Brirks, Photophysics of Aromatic Molecules, Wiley,
15, 53; (c) C. L. Zuch, D. J. O'Mara and D. A. Cory-Slechta,
Toxicol. Appl. Pharmacol., 1998, 150, 174; (d) M. Ali and
A. Quinlan, Am. J. Clin. Pathol., 1977, 67, 77; (e) W. de
London, 1970; (b) H. Tong, Y. Hong, Y. Dong, M. Haubler,
J. W. Y. Lam, Z. Li, Z. Guo, Z. Guo and B. Z. Tang, Chem.
Commun., 2006, 3705.
Vries, P. F. A. M. Romkens and G. Schuetze, in Rev. 14 (a) B. Z. Tang and A. Qin, Aggregation-Induced Emission:
Environ. Contam. Toxicol, ed. G. W. Ware, 2007, vol. 191,
pp. 91–130.
3 (a) C. B. Ernhart, Reprod. Toxicol., 1992, 6, 21; (b)
D. Bellinger, A. Leviton, C. Waternaux and E. Allred,
Fundamentals, Wiley, New York, 2013; (b) J. Luo, Z. Xie,
J. W. Y. Lam, L. Cheng, H. Chen, C. Qiu, H. S. Kwok,
X. Zhan, Y. Liu, D. Zhu and B. Z. Tang, Chem. Commun.,
2001, 1740.
Environ. Res., 1985, 38, 119; (c) W. Jedrychowski, F. Perera, 15 For selected recent reviews on AIE-active materials and their
J. Jankowski, V. Rauh, E. Flak, K. L. Caldwell, R. L. Jones,
A. Pac and I. Lisowska-Miszczyk, Int. J. Hyg. Environ.
Health, 2008, 211, 345.
4 S. Panich, K. A. Wilson, P. Nuttall, C. K. Wood, T. Albrecht
and J. B. Edel, Anal. Chem., 2014, 86, 6299.
applications, see: (a) J. Mei, Y. Hong, J. W. Y. Lam, A. Qin,
Y. Tang and B. Z. Tang, Adv. Mater., 2014, 26, 5429; (b)
Z. Chi, X. Zhang, B. Xu, X. Zhou, C. Ma, Y. Zhang, S. Liu
and J. Xu, Chem. Soc. Rev., 2012, 41, 3878; (c) Y. Hong,
J. W. Lam and B. Z. Tang, Chem. Soc. Rev., 2011, 40, 5361;
(d) H. Hong, J. W. Y. Lam and B. Z. Tang, Chem. Commun.,
2009, 4332.
5 (a) X.-G. Li, H. Feng, M.-R. Huang, G.-L. Gu and
M. G. Moloney, Anal. Chem., 2012, 84, 134; (b)
This journal is © The Royal Society of Chemistry 2014
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16 For some recent examples on TPE-based chemosensors/ 17 For some recent examples of TPE-based molecules for
bioprobes, see: (a) H.-T. Feng, S. Song, Y.-C. Chen,
C.-H. Shen and Y.-S. Zheng, J. Mater. Chem. C, 2014, 2,
2353; (b) J. Zhang, Q. Yang, Y. Zhu, H. Liu, Z. Chi and
C.-Y. Su, Dalton Trans., DOI: 10.1039/c4dt01808g; (c)
N. Zhao, J. W. Y. Lam, H. H. Y. Sung, H. M. Su,
I. D. Williams, K. S. Wong and B. Z. Tang, Chem.–Eur. J.,
2014, 20, 133; (d) X. Wang, J. Hu, G. Zhang and S. Liu, J.
Am. Chem. Soc., 2014, 136, 9890; (e) H.-T. Feng and
Y.-S. Zheng, Chem.–Eur. J., 2014, 20, 195; (f) X. Lou,
C. W. T. Leung, C. Dong, Y. Hong, S. Chen, E. Zhao,
J. W. Y. Lam and B. Z. Tang, RSC Adv., 2014, 4, 33307; (g)
X. Wang, H. Liu, J. Li, K. Ding, Z. Lv, Y. Yang, H. Chen and
X. Li, Chem.–Asian J., 2014, 9, 784; (h) C. J. Kassl and
F. C. Pigge, Tetrahedron Lett., 2014, 55, 4810; (i) J.-H. Ye,
various other applications, see: (a) Y. Chen, M. Li,
Y. Hong, J. W. Y. Lam, Q. Zheng and B. Z. Tang, ACS Appl.
Mater. Interfaces, 2014, 6, 10783; (b) C. Zhang, S. Jin, S. Li,
X. Xue, J. Liu, Y. Huang, Y. Jiang, W.-Q. Chen, G. Zou and
X.-J. Liang, ACS Appl. Mater. Interfaces, 2014, 6, 5212; (c)
S. Yao, X. Yang, M. Yu, Y. Zhang and J.-X. Jiang, J. Mater.
Chem. A, 2014, 2, 8054; (d) W. Qin, K. Li, G. Feng, M. Li,
Z. Yang, B. Liu and B. Z. Tang, Adv. Funct. Mater., 2014, 24,
635; (e) C. W. T. Leung, Y. Hong, S. Chen, E. Zhao,
J. W. Y. Lam and B. Z. Tang, J. Am. Chem. Soc., 2013, 135,
62; (f) Z. Zhao, C. Y. K. Chan, S. Chen, C. Deng,
J. W. Y. Lam, C. K. W. Jim, Y. Hong, P. Lu, Z. Chang,
X. Chen, P. Lu, H. S. Kwok, H. Qiu and B. Z. Tang, J.
Mater. Chem., 2012, 22, 4527.
J. Liu, Z. Wang, Y. Bai, W. Zhang and W. He, Tetrahedron 18 For selected recent examples of various AIE-active materials
Lett., 2014, 55, 3688; (j) F. Hu, Y. Huang, G. Zhang, R. Zhao
and D. Zhang, Tetrahedron Lett., 2014, 55, 1471; (k)
T. Noguchi, B. Roy, D. Yoshihara, Y. Tsuchiya,
T. Yamamoto and S. Shinkai, Chem.–Eur. J., 2014, 20, 381;
(l) D. G. Khandare, V. Kumar, A. Chattopadhyay,
M. Banerjee and A. Chatterjee, RSC Adv., 2013, 3, 16981;
(m) J. Mei, Y. Wang, J. Tong, J. Wang, A. Qin, J. Z. Sun and
B. Z. Tang, Chem.–Eur. J., 2013, 19, 613; (n) J. Li, J. Liu,
J. W. Y. Lam and B. Z. Tang, RSC Adv., 2013, 3, 8193; (o)
J. Liang, R. T. K. Kwok, H. Shi, B. Z. Tang and B. Liu, ACS
Appl. Mater. Interfaces, 2013, 5, 8784; (p) C. Yu, Y. Wu,
F. Zeng, X. Li, J. Shi and S. Wu, Biomacromolecules, 2013,
14, 4507; (q) H. Liu, Z. Lv, K. Ding, X. Liu, L. Yuan,
H. Chen and X. Li, J. Mater. Chem. B, 2013, 1, 5550; (r)
Y. Yan, Z. Che, X. Yu, X. Zhi, J. Wang and H. Xu, Bioorg.
Med. Chem., 2013, 21, 508; (s) T. Han, X. Feng, B. Tong,
J. Shi, L. Chen, J. Zhi and Y. Dong, Chem. Commun., 2012,
48, 416; (t) G. Huang, G. Zhang and D. Zhang, Chem.
Commun., 2012, 48, 7504; (u) X. Wang, J. Hu, T. Liu,
G. Zhang and S. Liu, J. Mater. Chem., 2012, 22, 8622; (v)
Y. Liu, Z. Wang, G. Zhang, W. Zhang, D. Zhang and
X. Jiang, Analyst, 2012, 137, 4654; (w) Y. Hong,
other than TPE and their applications, see: (a) N. Na,
F. Wang, J. Huang, C. Niu, C. Yang, Z. Shang, F. Han and
J. Ouyang, RSC Adv., 2014, 4, 35459; (b) L. Wang, D. Wang,
H. Lu, H. Wang, L. Xue and S. Feng, Appl. Organomet.
Chem., 2013, 27, 529; (c) O. Simalou, R. Lu, P. Xue, P. Gong
and T. Zhang, Eur. J. Org. Chem., 2014, 2014, 2907; (d)
G. Zhang, A. Ding, Y. Zhang, L. Yang, L. Kong, X. Zhang,
X. Tao, Y. Tian and J. Yang, Sens. Actuators, B, 2014, 202,
209; (e) C. Y. K. Chan, J. W. Y. Lam, Z. Zhao, S. Chen,
P. Lu, H. H. Y. Sung, H. S. Kwok, Y. Ma, I. D. Williams and
B. Z. Tang, J. Mater. Chem. C, 2014, 2, 4320; (f) X. Tang,
L. Yao, H. Liu, F. Shen, S. Zhang, H. Zhang, P. Lu and
Y. Ma, Chem.–Eur. J., 2014, 20, 7589; (g) H. Zhang, Y. Qu,
Y. Gao, J. Hua, J. Li and B. Li, Tetrahedron Lett., 2013, 54,
9099; (h) W. Z. Yuan, Y. Gong, S. Chen, X. Y. Shen,
J. W. Y. Lam, P. Lu, Y. Lu, Z. Wang, R. Hu, N. Xie,
H. S. Kwok, Y. Zhang, J. Z. Sun and B. Z. Tang, Chem.
Mater., 2012, 24, 1518; (i) X. Zhang, X. Zhang, S. Wang,
M. Liu, L. Tao and Y. Wei, Nanoscale, 2013, 5, 147; (j)
J. Mei, J. Wang, J. Z. Sun, H. Zhao, W. Yuan, C. Deng,
S. Chen, H. H. Y. Sung, P. Lu, A. Qin, H. S. Kwok, Y. Ma,
I. D. Williams and B. Z. Tang, Chem. Sci., 2012, 3, 549.
M. Haussler, J. W. Y. Lam, Z. Li, K. Sin, Y. Dong, H. Tong, 19 S. Hazra, S. Balaji, M. Banerjee, A. Ganguly, N. N. Ghosh and
J. Liu, A. Qin, R. Renneberg and B. Z. Tang, Chem.–Eur. J.,
2008, 14, 6428; (x) L. Liu, G. Zhang, J. Xiang, D. Zhang and
D. Zhu, Org. Lett., 2008, 10, 4581.
A. Chatterjee, Anal. Methods, 2014, 6, 3784; V. Kumar,
M. Banerjee and A. Chatterjee, Talanta, 2012, 99, 610.
20 X.-F. Duan, J. Zeng, J.-W. Lu and Z.-B. Zhang, J. Org. Chem.,
2006, 71, 9873.
47080 | RSC Adv., 2014, 4, 47076–47080
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