A highly selective and sensitive polymer-based OFF-ON fluorescent sensor for Hg2+ detection incorporating salen and perylenyl moieties

Article abstract of DOI:10.1039/c1jm14037j

A chiral conjugated polymer sensor with incorporated (R,R)-salen and perylenyl moieties in the main chain backbone could be obtained by the polymerization of 1,7-bis((3-formyl-4-hydroxyphenyl)ethynyl)perylene-3,4:9,10- tetracarboxylic tetrabutylate (M-1) with (R,R)-1,2-diaminocyclohexane (M-2) via a nucleophilic addition-elimination reaction. The polymer sensor can emit the fluorescence situated at 635 nm due to the introduction of a strong fluorophore perylenyl group. Compared with the other cations (including Na⁺, K⁺, Ca²⁺, Ag⁺, Ni²⁺, Cd ²⁺, Pb²⁺, Cr³⁺ Al³⁺, Fe ³⁺, Co²⁺, Zn²⁺), only Hg²⁺ can lead to the most pronounced response of the polymer sensor, which is as high as a 26-fold fluorescence enhancement without interference from other metal ions. More importantly, the fluorescent color of the polymer sensor displays an obvious change from red to bright yellow upon addition of Hg²⁺, which could be easily detected by the naked eye. The results indicate that the polymer sensor with incorporated (R,R)-salen and perylenyl moieties can be favorably utilized for the development of a potential sensor for Hg²⁺ detection.

Full text of DOI:10.1039/c1jm14037j

View Article Online / Journal Homepage / Table of Contents for this issue
Dynamic Article Links <
C
Journal of
Materials Chemistry
Cite this: J. Mater. Chem., 2012, 22, 478
www.rsc.org/materials
PAPER
A highly selective and sensitive polymer-based OFF-ON fluorescent sensor for
Hg2+ detection incorporating salen and perylenyl moieties†
*
Junfeng Li, Yuanzhao Wu, Fengyan Song, Guo Wei, Yixiang Cheng and Chengjian Zhu
Received 18th August 2011, Accepted 10th October 2011
DOI: 10.1039/c1jm14037j
A chiral conjugated polymer sensor with incorporated (R,R)-salen and perylenyl moieties in the main
chain backbone could be obtained by the polymerization of 1,7-bis((3-formyl-4-hydroxyphenyl)
ethynyl)perylene-3,4:9,10-tetracarboxylic tetrabutylate (M-1) with (R,R)-1,2-diaminocyclohexane (M-
2) via a nucleophilic addition–elimination reaction. The polymer sensor can emit the fluorescence
situated at 635 nm due to the introduction of a strong fluorophore perylenyl group. Compared with the
other cations (including Na+, K+, Ca2+, Ag+, Ni2+, Cd2+, Pb2+, Cr3+ Al3+, Fe3+, Co2+, Zn2+), only Hg2+
can lead to the most pronounced response of the polymer sensor, which is as high as a 26-fold
fluorescence enhancement without interference from other metal ions. More importantly, the
fluorescent color of the polymer sensor displays an obvious change from red to bright yellow upon
addition of Hg2+, which could be easily detected by the naked eye. The results indicate that the polymer
sensor with incorporated (R,R)-salen and perylenyl moieties can be favorably utilized for the
development of a potential sensor for Hg2+ detection.
communication along the polymer backbone. Swager et al.4
Introduction
reported that the delocalizable p-electronic conjugated ‘‘molec-
ular wire’’ polymer can greatly amplify the responsive fluores-
cence change due to facile energy migration along the polymer
backbone upon light excitation. As a result, a single conjugated
polymer provides an enhanced optical response relative to one of
its monomer units, and conjugated polymers can be used as
optical platforms in highly sensitive chemical and biological
sensors. Various perylenyl derivatives are promising materials
for organic solar cells,5 organic field-effect transistors,6 organic
light-emitting diodes7 due to their excellent thermal- and photo-
stability, strong fluorophores, high luminescence efficiency, and
novel optoelectronic properties. So far, perylene-based fluores-
cent sensors for metal ion detection have rarely been reported.8
Wang and co-workers designed a method for the selective sensing
of Hg2+ by utilizing a perylene fluorescence probe and a thymine-
rich oligonucleotides interaction with Hg2+ leading to a signifi-
cant fluorescence enhancement.8g However, there is no report on
polymer-based fluorescence sensors incorporating salen and
perylenyl moieties for selective Hg2+ detection.
Mercury is one of the most toxic heavy metal elements due to its
high affinity for thiol groups in proteins and enzymes. This leads
to the dysfunction of cells and consequently causes a wide range
of diseases, even in a low concentration, such as digestive, kidney
and especially neurological disorders.1 Though several tech-
niques are currently available for Hg2+ detection, they require
expensive instruments, well-controlled experimental conditions
and complicated sample-pretreatment procedures. It is very
important to develop a highly selective and sensitive sensor for
mercury ions in biological and environmental samples.2
Recently, fluorescent sensors for the detection of heavy and
transition metal ions have been widely investigated due to their
high sensitivity, selectivity, fast response, low cost and easy signal
detection. Therefore, fluorescence is still of particular signifi-
cance for the design of a suitable chemosensor for the rapid
determination of mercury in biological and environmental
samples.
In the last few decades, many fluorescent sensors for mercury
ion detection have been reported, but most of them were based
on small molecules, only a few were polymer-based sensors.3 An
advantage of using fluorescent conjugated polymers over small
molecules is that signal amplification occurs from electronic
Salen, as a well-known building block, has been widely used
for constructing chelation-enhanced fluorescence sensors for
transition metal ion detections due to the potentially tetradentate
N2O2 donor.9 Recently, our group reported a chiral fluorescence
polymer sensor bearing a (R,R)-salen unit, which exhibited high
selectivity and sensitivity for Zn2+ detection without interference
from other metal ions.10 In this paper, perylene was chosen as
a fluorophore dye, and (R,R)-salen acts as a chelating ligand. The
polymer sensor with incorporated (R,R)-salen and perylenyl
moieties in the main chain backbone can exhibit a highly selective
Key Lab of Mesoscopic Chemistry of MOE, School of Chemistry and
Chemical Engineering, Nanjing University, Nanjing, 210093, China.
E-mail: yxcheng@nju.edu.cn; Fax: +86-25-8368-5199; Tel: +86-25-
8331-7761
† Electronic supplementary information (ESI) available: See DOI:
10.1039/c1jm14037j
478 | J. Mater. Chem., 2012, 22, 478–482
This journal is ª The Royal Society of Chemistry 2012

View Article Online
and sensitive fluorescence response toward Hg2+ without inter-
ference from other metal ions. More importantly, the polymer
sensor appears to give an obvious and characteristic color change
from red to bright yellow, which indicates that the resulting
polymer-based fluorescence sensor can serve as a ‘‘naked-eye’’
indicator for Hg2+ recognition.
polymer can provide a desirable thermal property for the prac-
tical application as a fluorescence sensor.
Optical properties
Fig. 1 illustrates the UV-vis absorption and fluorescence spectra
of the model compound 2 and polymer-based fluorescence sensor
(1.0 ꢀ 10ꢁ5 mol Lꢁ1 in THF). As can be observed in Fig. 1, the
UV-vis absorption maxima lmax of 2 appeared at 241 nm, and
the conjugated polymer showed a strong and broad absorption
in the region from 400 to 570 nm. A large red shift in the elec-
tronic absorption of the polymer can be attributed to the effec-
tive p–p* conjugated segments of the polymer main chain
backbone. The polymer sensor can emit the red fluorescence
situated at 635 nm under ultraviolet light (365 nm) even in low
concentration (1 ꢀ 10ꢁ5 mol Lꢁ1) due to the introduction of
a strong fluorophore perylenyl group. The fluorescent emission
Experimental
Metal ion titration
Each metal ion titration experiment was started using 5.0 mL of
a polymer solution with a known concentration (1.0 ꢀ 10ꢁ5 mol
Lꢁ1 corresponding to (R,R)-salen moiety in THF). Mercury
perchlorate salt (1.0 ꢀ 10ꢁ3 mol Lꢁ1 in CH3CN) and other
various metal salts (nitrate, 1.0 ꢀ 10ꢁ2 mol Lꢁ1 in H2O) were used
for the titration. Polymer–metal complexes were produced by
adding aliquots of a solution of the selected metal salt to the THF
solution of the polymer. All types of measurements were taken
2 h after the addition of the metal salt to the polymer solution.
wavelengths of 2, 3 and the polymer sensor appear at 398 (lex
¼
310 nm), 495 (lex ¼ 430 nm) and 635 nm (lex ¼ 440 nm),
respectively. Compared to 2 and 3, the conjugated polymer
sensor shows a large red shift due to the extended p-electronic
structure in the main chain backbone.13 The greatly enhanced
fluorescence of the polymer sensor is expected to have the
potential application in the polarized light-emitting materials
and fluorescence chemosensor on the sensitivity in metal ions
sensing.
Results and discussion
Synthesis and characterization of the polymer-based fluorescence
sensor
The synthesis procedures of the model compound 2 and polymer-
based fluorescence sensor are outlined in Fig S1†. Compound 3,
1,7-dibromoperylene-3,4:9,10-tetracarboxylictetr-abutylate could
be synthesized according to the literature.11 Monomer M-1, 1,7-
bis((3-formyl-4-hydroxyphenyl)ethynyl)-perylene-3,4:9,10-tetra-
carboxylic tetrabutylate, was synthesized by a three-step reaction
from the starting material 3,4:9,10-perylene-tetracarboxylic acid
dianhydride.12 The polymer sensor incorporating (R,R)-salen
and perylenyl moieties in the main chain backbone could be
obtained by the Schiff–base formation via a nucleophilic addi-
tion–elimination reaction between M-1 and (R,R)-1,2-dia-
minocyclohexane (M-2) as a dark-red powder in 59% yield. The
specific rotation value ([a]D25) of the model compound 2 is ꢁ0.059
(c ¼ 0.49, THF), but [a]2D5 of the sensor is ꢁ270 (c ¼ 0.01, THF).
The optical rotation of the chiral polymer is much larger than its
chiral monomers, which is attributed to the amplification of
chiral signals of the conjugated polymer. The weight-average
molecular weight (Mw), the number-average molecular weight
(Mn), and polydispersity index (PDI) of the sensor were deter-
mined by gel permeation chromatography (GPC) using poly-
styrene standards in THF, the values of them are 12480, 7710 and
1.6, respectively. The GPC result shows the moderate molecular
weight. The sensor is an air stable solid and shows that it is
readily soluble in common organic solvents, such as CHCl3,
CH2Cl2, THF and toluene, which can be attributed to the flexible
n-butoxy substitutents in the side chain of the polymer. In
addition, the ethynyl linker can reduce steric hindrance between
the perylenyl and phenyl groups which also has a beneficial
influence on the stability of the resulting chiral polymer. Ther-
mogravimetric analysis (TGA) of the polymer was carried out
under a N2 atmosphere at a heating rate of 10 ꢂC minꢁ1
(Fig S11†). The result shows that the polymer sensor has a high
The selective and sensitive recognition of the polymer sensor
towards Hg2+
The effects of the fluorescence response behavior of the sensor
towards Hg2+ have been investigated. Fig. 2 shows the fluores-
cence spectra of the polymer-based fluorescence sensor (1.0 ꢀ
10ꢁ5 mol Lꢁ1 in THF) upon addition of mercury ions in
anCH3CN solution (lex ¼ 440 nm). The polymer sensor appears
to have a weaker emission peak situated at 635 nm. However, the
emission intensities of the Hg2+-containing polymer complex
exhibits a gradual enhancement response, as high as 26-fold,
upon the addition of Hg2+ with a concentration molar ratio from
0.1 to 3.0 at a concentration of 1.0 ꢀ 10ꢁ3 mol Lꢁ1. In addition,
a large blue shift of about 85 nm for the emission spectrum peak
of the Hg2+-containing polymer complex can be observed, which
can be attributed to an ICT (intramolecular-charge-transfer)
ꢂ
thermal stability without loss of weight below 250 C and tends
Fig. 1 UV-vis and fluorescence spectra of the model compound 2 (1 ꢀ
10ꢁ5 mol Lꢁ1) and polymer-based fluorescence sensor (1 ꢀ 10ꢁ5 mol Lꢁ1).
to completely decompose at 700 ꢂC. Therefore, the resulting
This journal is ª The Royal Society of Chemistry 2012
J. Mater. Chem., 2012, 22, 478–482 | 479

View Article Online
and Jones,15a the polymer sensor can be thought of as a conju-
gated polymer PET chemosensor, in which the conjugated
polymer backbone is the fluorophore and the salen or tetrabu-
tylate groups are the receptors. In such systems, the salen and
tetrabutylate receptors contain the high energy non-bonding
electron pairs. In the absence of analytes, these electron pairs
quench the fluorescence of the fluorophore by rapid intra-
molecular electron transfer from the receptor to the excited flu-
orophore. When these electron pairs are coordinated to Hg2+
(Lewis acid cations) in solution, the HOMO of the receptor is
lowered. This decreases the driving force for the PET process and
can turn on the fluorescence of the fluorophore. To our knowl-
edge, most fluorescence sensors based on small organic molecules
or conjugated polymers for Hg2+ detection exhibit a fluorescence
quenching effect.15b Although few small molecule sensors work in
‘‘turn-on’’ mode,16 very few examples of fluorescence-based
polymer sensors towards Hg2+ could exhibit the fluorescence
enhancement effect.17 Since fluorescence quenching is not only
disadvantageous for a high signal output upon complexation,
but also hampers temporal separation of spectrally similar
complexes with time-resolved fluorometry. The design of che-
mosensors with an obvious fluorescence enhancement response
for the detection of mercury still remains an attractive topic.18
Further evidence for the interaction of the salen and tetrabu-
Fig. 2 Fluorescence spectra of the polymer (1.0 ꢀ 10ꢁ5 mol Lꢁ1) in THF
with increasing amounts of Hg2+ (0, 0.1, 0.2, 0.4, 0.8, 1.0, 1.2, 1.6, 2.0, 2.4,
2.8, 3.0 ꢀ 10ꢁ5 mol Lꢁ1) (lex ¼ 440 nm); Inset: fluorescence enhancement
values (F/F0) vs. the increasing concentration of Hg2+
.
mechanism.14 More importantly, the Hg2+-polymer solution
appears to undergo an obvious and characteristic color change
from red to bright yellow, which can be easily detected by the
naked eye (Fig. 3). The fluorescence enhancement in its response
behavior of the sensor towards Hg2+ can be attributed to the
suppressed PET (photoinduced-electron-transfer) quenching
when Hg2+ coordinates with the tetradentate N2O2 donor of the
(R,R)-salen moiety in the polymer main chain and oxygen atoms
of the tetrabutylate groups in the side chain of polymer sensor
(Fig. 3). It can also be observed that the titration curve keeps to
a nearly linear correlation with the concentration molar ratio of
Hg2+ from 0.1 to 3.0. The linear titration curve of fluorescence
spectra of the polymer sensor demonstrates that chemodosimeter
responds to Hg2+ in a 1 : 3 stoichiometry ratio. In this range of
concentrations, the curve could be best described by the equation
F ¼ 4.346 ꢁ 32.241[Hg2+], with R ¼ 0.99404, N ¼ 10 (Fig S12†).
According to the equation and the standard deviation of the
blank, the polymer sensor has a detection limit of 7.28 ꢀ
10ꢁ7 mol Lꢁ1 for Hg2+.
tylate moieties with Hg2+ was provided by H NMR titration
1
experiments of the polymer sensor with Hg2+ in CD3CN (Fig
S10†). The 1H NMR spectra of the polymer sensor demonstrates
that the protons in the lateral region of the perylenyl tetrabuty-
late core (–COOCH2–) shift downfield from 4.36 to 4.58 ppm
upon addition of Hg2+ (3 equiv.) to the polymer solution in
CDCl3, which shows coordination and chelation between the
ester groups and Hg2+. Meanwhile, obvious upfield shifts (–CH–
CH–) from 3.47 to 4.23 can be also observed for the protons of
(R,R)-salen, which indicates the direct interaction between (R,R)-
salen groups and Hg2+.
In this paper, we further explored the utility of the polymer
sensor as an ion-selective fluorescence probe for Hg2+. The
experiments on other various cations were also conducted under
the same conditions as the Hg2+ determination, such as Zn2+, Fe3+,
Cd2+, Na+, Ag+, K+, Al3+, Cr3+, Ca2+, Ni2+, Pb2+, Cu2+ and Co2+
(Fig. 4). In the experiment, the fluorescence spectra of the sensor
(1.0 ꢀ 10ꢁ5 mol Lꢁ1) were determined at room temperature in the
absence and presence of 3.0 equiv. of a metal ion (Fig S15†). As
Compound 3 shows a strong fluorescence at 495 nm, but the
model compound 2 emits a weaker fluorescence at 398 nm. Upon
addition of 0.1–2.0 equiv. of Hg2+ ions to the solution of 2 and 3,
the compound 2-/3-Hg2+ complexes show nearly no changes in
emission spectra (Fig S13–S14†). On the contrary, the sensor
incorporating (R,R)-salen and perylenyl moieties can exhibit the
most pronounced fluorescence enhancement response and a large
blue shift on Hg2+ complexation. According to the reports of Fan
Fig. 4 The selectivity of the polymer sensor toward Hg2+ and other
metal ions. In these experiments, the fluorescence measurement was taken
at lex ¼ 440 nm from 10 mM of the polymer in THF at room temperature
and in the absence and presence of 3.0 equiv. of a metal ion.
Fig. 3 Hg2+ induced ICT ON–OFF.
480 | J. Mater. Chem., 2012, 22, 478–482
This journal is ª The Royal Society of Chemistry 2012

View Article Online
quantification of mercury in environmental and biological
samples.
Acknowledgements
This work was supported by the National Natural Science
Foundation of China (No. 20832001, 21074054) and National
Basic Research Program of China (2010CB923303).
References
1 (a) L. Zhang, T. Li, B. Li, J. Li and E. Wang, Chem. Commun., 2010,
46, 1476–1478; (b) J. Liu and Y. Lu, Angew. Chem., Int. Ed., 2007, 46,
7587–7590; (c) Y. K. Yang, K. J. Yook and J. S. Tae, J. Am. Chem.
ꢀ
Soc., 2005, 127, 16760–16761; (d) A. Caballero, R. Martınez,
V. Lloveras, I. Ratera, J. Vidal-Gancedo, K. Wurst, A. Tarraga,
P. Molina and J. Veciana, J. Am. Chem. Soc., 2005, 127, 15666–
15667; (e) E. M. Nolan and S. J. Lippard, J. Am. Chem. Soc., 2007,
129, 5910–5918.
Fig. 5 Fluorescence enhancement degree of the polymer sensor (1.0 ꢀ
10ꢁ5 mol Lꢁ1) in the mixed metal ions (each 3.0 ꢀ 10ꢁ5 mol Lꢁ1).
ꢀ
2 (a) J. Du, J. Fan, X. Peng, P. Sun, J. Wang, H. Li and S. Sun, Org.
Lett., 2010, 12, 476–479; (b) R. R. Avirah, K. Jyothish and
D. Ramaiah, Org. Lett., 2007, 9, 121–124; (c) D. Wu, W. Huang,
C. Duan, Z. Lin and Q. Meng, Inorg. Chem., 2007, 46, 1538–1540;
(d) H. H. Harris, I. J. Pickering and G. N. George, Science, 2003,
301, 1203–1203.
3 (a) I. Grabchev, S. Sali, R. Betcheva and V. Gregoriou, Eur. Polym.
J., 2007, 43, 4297–4305; (b) S. He, S. T. Iacono, S. M. Budy,
A. E. Dennis, Jr., D. W. Smith and R. C. Smith, J. Mater. Chem.,
2008, 18, 1970–1976.
4 (a) D. T. McQuade, A. E. Pullen and T. M. Swager, Chem. Rev., 2000,
100, 2537–2574; (b) S. W. Thomas, G. D. Joly and T. M. Swager,
Chem. Rev., 2007, 107, 1339–1386.
ꢀ
5 (a) J. L. Segura, N. Martın and D. M. Guldi, Chem. Soc. Rev., 2005,
34, 31–47; (b) H. Hoppe and N. S. Sariciftci, J. Mater. Res., 2011, 19,
a result, only Hg2+ can lead to the most pronounced fluorescence
enhancement response of the polymer sensor. However, Cd2+,
Ag+, Ca2+, Al3+, Cr3+ and Pb2+ can slightly enhance the fluores-
cence response (I/I0 ꢁ 1 < 0.50), and Al3+ and Cr3+ induced
a continuous blue shift of the emission peak from 635 to 550 nm.
Meanwhile, Co2+ and Ni2+ can effectively quench the fluorescence
of the sensor (I/I0 ꢁ 1 < ꢁ0.60), and Cu2+ can lead to almost
complete quenching of the sensor (I/I0 ꢁ 1 ¼ ꢁ0.97). Under the
same conditions Zn2+, Na+ and K+ caused limited quenching of
the fluorescence intensity. In most cases, the salen ligand has
a good affinity for Zn2+, However, our resulting polymer sensor
can exhibit a high selectivity and sensitivity towards Hg2+ over
Zn2+. It is possible that the nitrogen atoms of the salen unit did not
participate in binding with a Zn2+ ion, which induced the fluo-
rescence of sensor quenching.19
€
1924–1945; (c) L. Schmidt-Mende, A. Fechtenkotter, K. Mullen,
E. Moons, R. H. Friend and J. D. MacKenzie, Science, 2001, 293,
1119–1123; (d) X. Zhan, Z. Tan, B. Domercq, Z. An, X. Zhang,
S. Barlow, Y. Li, D. Zhu, B. Kippelen and S. R. Marder, J. Am.
Chem. Soc., 2007, 129, 7246–7247.
In this paper, we further investigated the selectivity of the
polymer sensor for Hg2+ while in the presence of a Hg-polymer
treated with other metal ions (Fig. 5). The fluorescence response
was measured using the metal ion solution titrations in
the presence of the mercury ion, with ions such as Na+, K+, Ca2+,
Cr3+, Pb2+ and Cd2+, the fluorescence enhancement degree
(F/F0 ꢁ 1) of the polymer sensor is ꢁ0.07, 0.26, 16.94, ꢁ18.13,
ꢁ13.16, ꢁ4.64 and 2.02%, respectively. Comparison of the
polymers that contain both a mixture of ions (except the coex-
ising ions Cu2+ and Co2+) and single Hg2+, the fluorescence
intensities of the polymers do not appear to have any obvious
changes. Herein, the fluorescence intensity of the sensor can not
be influenced in the presence of mercury ions during the titration
of various metal ions, which demonstrates that the polymer
sensor can serve as highly selective ‘‘turn-on’’ fluorescent che-
modosimeter for the detection of Hg2+.
6 (a) C. D. Dimitrakopoulos and P. R. L. Malefant, Adv. Mater., 2002,
14, 99–117; (b) B. A. Jones, M. J. Ahrens, M. H. Yoon, A. Facchetti,
T. J. Marks and M. R. Wasielewski, Angew. Chem., Int. Ed., 2004, 43,
ꢀ
€
ꢀ
6363–6366; (c) A. J. Jimenez, F. Spanig, M. S. Rodrıguez-Morgade,
S. Cai, S. Fukuzumi, D. M. Guldi and T. Torres, Org. Lett., 2007,
9, 2481–2484; (d) H. Z. Chen, M. M. Ling, X. Mo, M. M. Shi,
M. Wang and Z. Bao, Chem. Mater., 2007, 19, 816–824; (e)
B. J. Jung, N. J. Tremblay, M. L. Yeh and H. E. Katz, Chem.
Mater., 2011, 23, 568–582.
7 (a) A. Kraft, A. C. Grimsdale and A. B. Holmes, Angew. Chem., Int.
€
Ed., 1998, 37, 402–428; (b) U. Mitschke and P. Bauerle, J. Mater.
Chem., 2000, 10, 1471–1057.
8 (a) M. R. Wasielewski, J. Org. Chem., 2006, 71, 5051–5066; (b)
€
F. W. Wurthner, Chem. Commun., 2004, (14), 1564–1579; (c)
C. Zhao, Y. Zhang, R. Li, X. Li and J. Jiang, J. Org. Chem., 2007,
72, 2402–2410; (d) Y. Li, H. Zheng, Y. Li, S. Wang, Z. Wu, P. Liu,
Z. Gao, H. Liu and D. Zhu, J. Org. Chem., 2007, 72, 2878–2885; (e)
X. He, H. Liu, Y. Li, S. Wang, Y. Li, N. Wang, J. Xiao, X. Xu and
D. Zhu, Adv. Mater., 2005, 17, 2811–2815; (f) X. Guo, D. Zhang
and D. Zhu, Adv. Mater., 2004, 16, 125–130; (g) B. Wang,
F. Wang, H. Jiao, X. Yang and C. Yu, Analyst, 2010, 135, 1986–1991.
9 (a) P. G. Cozzi, Chem. Soc. Rev., 2004, 33, 410–421; (b) Z. L. Chu,
W. Huang, L. Wang and S. H. Gou, Polyhedron, 2008, 27, 1079–
1092; (c) D. Pucci, I. Aiello, A. Bellusci, A. Crispini, M. Ghedini
and M. L. Deda, Eur. J. Inorg. Chem., 2009, 28, 4274–4281; (d)
M. Hosseini, Z. Vaezi, M. R. Ganjali, F. Faridbod, S. D. Abkenar,
K. Alizadeh and M. Salavati-Niasari, Spectrochim. Acta. A., 2009,
73, 1386–1425; (e) N. Singh, N. Kaur, B. McCaughan and
J. F. Callan, Tetrahedron Lett., 2010, 51, 3385–3387; (f) S. Jammi,
L. Rout and T. Punniyamurthy, Tetrahedron: Asymmetry, 2007, 18,
2016–2020; (g) S. Sakthivel and T. Punniyamurthy, Tetrahedron:
Asymmetry, 2010, 21, 2834–2840; (h) D. Yu, J. F. Li, X. X.J.,
F. Y. Song, Y. X. Cheng and C. J. Zhu, Org. Lett., 2011, 13, 2252–
2255.
Conclusion
In conclusion, we have designed a novel polymer-based OFF–
ON fluorescence sensor incorporating perylenyl and salen
moieties in the main chain backbone. The polymer sensor can
exhibit a highly selective and sensitive fluorescence enhancement
response for Hg2+ detection without interference from other
metal ions. We expect that the present design strategy and the
remarkable photophysical properties of this resulting polymer-
based fluorescence sensor is a potential tool for the detection and
This journal is ª The Royal Society of Chemistry 2012
J. Mater. Chem., 2012, 22, 478–482 | 481

View Article Online
10 Y. Xu, J. Meng, L. Meng, Y. Dong, Y. Cheng and C. Zhu, Chem.–
Eur. J., 2010, 16, 12898–12903.
11 (a) X. Mo, H. Z. Chen, M. M. Shi and M. Wang, Chem. Phys. Lett.,
2006, 417, 457–460; (b) Y. Qin, J. Shi, W. Wu, X. L. Li, Z. X. Guo and
D. B. Zhu, J. Phys. Chem. B, 2003, 107, 12899–12901.
J. Fan, Org. Biomol. Chem., 2007, 5, 226–228; (g) K. Hanaoka,
Y. Muramatsu, Y. Urano, T. Terai and T. Nagano, Chem.–Eur. J.,
2010, 16, 568–572.
15 (a) L. J. Fan, Y. Zhang and W. E. Jones, Macromolecules, 2005, 38,
2844–2849; (b) A. P. de Silva, H. Q. N. Gunaratne, T. Gunnlaugsson,
A. J. M. Huxley, C. P. McCoy, J. T. Rademacher and T. E. Rice,
Chem. Rev., 1997, 97, 1515–1566.
12 (a) M. C. Baier, J. Huber and S. Mecking, J. Am. Chem. Soc., 2009,
€
131, 14267–14273; (b) F. Wurthner, V. Stepanenko, Z. Chen,
C. R. Saha-Moller, N. Kocher and D. Stalke, J. Org. Chem., 2004,
€
ꢀ
ꢀ~
16 (a) J. V. Ros-Lis, M. D. Marcos, R. Martinez-Manez, K. Rurack and
J. Soto, Angew. Chem., Int. Ed., 2005, 44, 4405–4407; (b) E. M. Nolan
and S. J. Lippard, J. Am. Chem. Soc., 2003, 125, 14270–14271; (c)
L. Prodi, C. Bargossi, M. Montalti, N. Zaccheroni, N. Su,
J. S. Bardshaw, R. M. Izatt and P. B. Savage, J. Am. Chem. Soc.,
2000, 122, 6769–6770; (d) B. Tang, B. Ding, K. Xu and L. Tong,
Chem.–Eur. J., 2009, 15, 3147–3151.
69, 7933–7939; (c) C. Huang, S. Barlow and S. R. Marder, J. Org.
Chem., 2011, 76, 2386–2407; (d) Z. An, J. Yu, B. Domercq,
S. C. Jones, S. Barlow, B. Kippelen and S. R. Marder, J. Mater.
Chem., 2009, 19, 6688–6698.
13 (a) X. Huang, J. Meng, Y. Dong, Y. Cheng and C. Zhu, J. Polym.
Sci., Part A: Polym. Chem., 2010, 48, 997–1006; (b) J. Li, J. Meng,
X. Huang, Y. Cheng and C. Zhu, Polymer, 2010, 51, 3425–3430;
(c) X. Huang, J. Meng, Y. Dong, Y. Cheng and C. Zhu,
Polymer, 2010, 51, 3064–3067; (d) Y. Liu, S. Zhang, Q. Miao,
L. Zheng, L. Zong and Y. Cheng, Macromolecules, 2007, 40,
4839–4847.
14 (a) S. Atilgan, I. Kutuk and T. Ozdemir, Tetrahedron Lett., 2010, 51,
892–894; (b) M. Yuan, Y. Li, J. Li, C. Li, X. Liu, J. Lv, J. Xu, H. Liu,
S. Wang and D. Zhu, Org. Lett., 2007, 9, 2313–2316; (c) J. Wang,
X. Qian and J. Cui, J. Org. Chem., 2006, 71, 4308–4311; (d)
D. Maity and T. Govindaraju, Chem. Commun., 2010, 46, 4499–
4501; (e) C. Lu, Z. Xu, J. Cui, R. Zhang and X. Qian, J. Org.
Chem., 2007, 72, 3554–3557; (f) X. Peng, Y. Xu, S. Sun, Y. Wu and
17 (a) I. B. Kim and U. H. F. Bunz, J. Am. Chem. Soc., 2006, 128, 2818–
2819; (b) X. Liu, Y. Tang, L. Wang, J. Zhang, S. Song, C. Fan and
S. Wang, Adv. Mater., 2007, 19, 1471–1474.
18 (a) K. Rurack, M. Kollmannsberger, U. Resch-Genger and J. Daub,
J. Am. Chem. Soc., 2000, 122, 968–969; (b) X. Guo, X. Qian and L. jia,
J. Am. Chem. Soc., 2004, 126, 2272–2273.
19 (a) S. Foxon, J. Xu, S. Turba, M. Leibold, F. Hempel,
€
F. W. Heinemann, O. Walter, C. Wutele, M. Holthausen and
S. Schindler, Eur. J. Inorg. Chem., 2007, 3, 429–443; (b) A. Hazell,
C. J. McKenzie and L. P. Nielsen, J. Chem. Soc., Dalton Trans.,
1998, 1751–1756; (c) H. Wang, D. Wang, Q. Wang, X. Li and
C. A. Schalley, Org. Biomol. Chem., 2010, 8, 1017–1026.
482 | J. Mater. Chem., 2012, 22, 478–482
This journal is ª The Royal Society of Chemistry 2012