An efficient iodide ion chemosensor and a rewritable dual-channel security display material based on an ion responsive supramolecular gel

Article abstract of DOI:10.1039/c7ra06238a

By introducing multi-self-assembly driving forces, coordination binding sites and signal groups into the same molecule, a well designed functional gelator G1 was synthesized. The gelator G1 could form a stable Pb²⁺-coordinated supramolecular me

Full text of DOI:10.1039/c7ra06238a

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An efficient iodide ion chemosensor and
a rewritable dual-channel security display material
Cite this: RSC Adv., 2017, 7, 38210
based on an ion responsive supramolecular gel†
a
a
b
a
Lu Liu, Juan Liu, Feng Zheng,a You-Ming Zhang,
Hong Yaoa
*
*
Qi Lin,
a
*
and Tai-Bao Wei
By introducing multi-self-assembly driving forces, coordination binding sites and signal groups into the
same molecule, a well designed functional gelator G1 was synthesized. The gelator G1 could form
a stable Pb2+-coordinated supramolecular metallogel (PbG) accompanied with aggregation-induced
fluorescence emission (AIE). PbG shows the reversible selective fluorescent response for Iꢀ under a gel–
gel state. The detection limit of PbG for Iꢀ is 1.0 ꢁ 10ꢀ7 M. The AIE fluorescence of PbG could be
reversibly switched “on–off–on” under gel–gel states via alternatively adding Iꢀ and Pb2+ water solution
into PbG. Other anions could not induce similar stimuli-response for PbG. Interestingly, when a writing
brush dipped in Iꢀ water solution was used to write on the xerogel film of PbG, the film did not show
any color changes. However under UV at 365 nm, a clear dark writing image appeared. This dark writing
could be erased by brushing Pb2+ on the film. More interestingly, when the PbG film containing the
invisible Iꢀ writing was exposed to iodine vapor, a clear brown writing appeared on the film. However,
when this film was placed under the room atmosphere for one minute, the brown writing gradually
disappeared. Therefore, the PbG film could act as not only a convenient reversible Iꢀ detection test kit,
but also an erasable dual-channel security display material.
Received 4th June 2017
Accepted 21st July 2017
DOI: 10.1039/c7ra06238a
rsc.li/rsc-advances
However, although a signicant amount of effort has been
devoted to the development of metal ions coordinated supra-
1. Introduction
molecular gels,40 it is still a big challenge to design and
synthesize supramolecular gels that can optically sense a given
chemical stimulus with a specic selectivity. In view of this, as
a part of our research interest in supramolecular chemistry,41–45
we attempted to control the stimuli-response properties of
supramolecular gels through the competitive coordination
between supramolecular gelators, metal ions and guest
compounds.
Herein, we designed and synthesized a gelator G1 based
on multi-assembly driving forces,46–49 uorescent signal
groups50 and coordination binding sites.51,52 The gelator G1
could form a stable supramolecular organogel in various
solvents at very low critical gelation concentrations (CGCs).
Aer the addition of Pb2+ to the G1 ethanol organogel (OG),
OG could form a stable Pb2+-coordinated supramolecular
metallogel PbG accompanied by the pale blue aggregation-
induced uorescence emission (AIE).53–56 The AIE of PbG
could be reversibly controlled by iodide anions with a specic
selectivity in gel–gel states. PbG could act as not only
a convenient reversible Iꢀ detection test kit, but also an
erasable dual-channel security display material. It is worth
mentioning that the security display materials have become
of increasing importance.57,58
In recent years, stimuli-responsive gels,1–8 as a type of smart
supramolecular materials, have become one of the most signif-
icant realms due to their wide application prospects in chemo-
sensors,9–12 biomaterials,13–16 displays,17 physical materials,18–22
chemical engineering23–26 and other relevant areas.27–32 Taking
advantage of the dynamic and reversible nature of noncovalent
interactions, such as strong van der Waal's forces, hydrogen
bonds and p–p stacking,33 the stimuli-responsive supramolec-
ular gels can sense, process and actuate a response to an external
change without assistance.34–36 Moreover, metal ions-
coordinated supramolecular gels37 have become a focus due to
their tunable coordination binding strength and fascinating
redox, optical, electronic, as well as magnetic properties of the
metal ions.38,39 These excellent properties would bring benet to
the applications of smart materials.
aKey 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, P.
R. China. E-mail: linqi2004@126.com; weitaibao@126.com
bCollege of Chemical Engineering, Northwest University for Nationalities, Lanzhou,
730000, P. R. China. E-mail: liujuan656@126.com
† Electronic supplementary information (ESI) available. See DOI:
10.1039/c7ra06238a
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2. Experimental
As show in Scheme 1, the compound 3,4,5-tris(hexadecyloxy)
benzohydrazide was synthesized according to the literature-
reported methods.59 G1 was synthesized as follow: p-nitro-
benzaldehyde
(1
mmol),
3,4,5-tris(hexadecyloxy)-
benzohydrazide (1 mmol) and acetic acid (0.1 mL, as a cata-
lyst) were added to ethanol (20 mL). Then, the reaction mixture
was stirred under reuxed conditions for 24 hours. Aer the
solvent was removed, the precipitated G1 was yielded and
recrystallized with CHCl3–EtOH to get the solid G1. Yield: 60%,
m.p.: 106–110 ꢂC, 1H NMR (400 MHz, CDCl3, Fig. S1†) d 9.30 (s,
–NH, 1H), 8.26 (d, J ¼ 8.7 Hz, –ArH, –CH, 3H), 7.90 (s, –ArH, 2H),
7.07 (s, ArH, 2H), 4.01 (d, J ¼ 3.8 Hz, –CH2, 6H), 1.95–1.71 (m,
–CH2, 6H), 1.36 (m, –CH2, 78H), 0.88 (t, J ¼ 6.5 Hz, –CH3, 9H).
13C NMR (150 MHz, CDCl3, Fig. S2†) d 152.76, 123.99, 107.96,
77.19, 76.98, 76.77, 73.59, 73.46, 69.44, 69.16, 60.93, 31.91,
30.30, 29.70, 29.64, 29.62, 29.55, 29.40, 29.38, 29.35, 29.30,
26.06, 22.67, 14.38, 14.08; IR (KBr, cmꢀ1) v: 3455 (–NH), 1715
(C]O), 1650 (CH]N). Anal. calcd. for C62H107N3O6: C 75.03, H
10.40, N 3.98; found: C 75.12, H 10.56, N 3.85. MS: ESI [M + H]+
m/z (Fig. S3†) found: 990.8284, calcd: 990.8233.
Fig. 1 Temperature dependent fluorescent spectra of the PbG (1%, in
ethanol, G1–Pb2+ ¼ 1 : 1) during gelation process (lex ¼ 340 nm). The
temperature was decreased from 85 ꢂC to 25 ꢂC and a fluorescence
spectrum was recorded every 5 ꢂC.
SCNꢀ, ClO4ꢀ, CNꢀ, CO32ꢀ, S2ꢀ and SO42ꢀ, 1 mol Lꢀ1) to PbG. As
shown in Fig. 2, when adding water solutions of various anions
to the small amount of metallogel PbG on a spot plate, only Iꢀ
could quench the uorescence of PbG, while other anions could
not. These results indicated that PbG could selectively sense Iꢀ,
which was attributed to Iꢀ competitively binding with Pb2+
.
Moreover, the Iꢀ response properties of PbG were investi-
gated by uorescence titrations. As shown in Fig. 3, with the
addition of Iꢀ into PbG, the spectra showed evident red shis,
which was attributed to the coordination of Iꢀ with Pb2+. In
PbG, Pb2+ coordinated with the gelator through the acylhy-
drazone moiety. When Iꢀ was added into PbG, Pb2+ coordinated
with Iꢀ and the acylhydrazone moiety was released, which
induced the uorescence spectra of the gel to undergo the red
shis. In addition, the emission intensity at 474 nm decreased
with increasing the concentration of Iꢀ. The detection limit of
the uorescence spectra changes, which was calculated on the
basis of 3d/S,60 was 2.037 ꢁ 10ꢀ6 M (Fig. S4†) for Iꢀ anion.
Interestingly, aer the addition of Pb2+ into the Iꢀ contain-
ing PbG, the uorescence of PbG recovered, which was attrib-
uted to the Pb2+ coordination with G1 again. These properties
3. Results and discussion
First, we carefully investigated the gelation properties of G1. As
shown in Table S1,† the gelator G1 could form a stable supra-
molecular organogel in various solvents at very low critical
gelation concentrations. Among these solvents, the gelator G1
showed the lowest CGC (0.40%, wt/v%, 10 mg mLꢀ1 ¼ 1%) and
the highest gel–sol transition temperature (78 ꢂC) in ethanol.
The G1-based supramolecular organogel OG in ethanol is more
stable than the gel in other solutions. Therefore, we investigated
the inuence of metal ions on the G1 organogel in ethanol.
Interestingly, aer the addition of Pb2+ to the G1 ethanol
organogel (OG), OG could form a stable Pb2+-coordinated
supramolecular metallogel PbG. As shown in Fig. 1, PbG has no
uorescence emission in hot ethanol solution (T > Tgel).
However, when the temperature of this hot ethanol solution
dropped below the Tgel of PbG, the emission intensity at 340 nm
showed an evident increase and reached a steady state, which
indicated that the uorescence emission of metallogel PbG was
aggregation-induced emission (AIE).
The anion response capability of the supramolecular met-
allogel PbG was primarily investigated by adding various anions
ꢀ
in water solutions (AcOꢀ, HSO4ꢀ, H2PO4ꢀ, Fꢀ, Clꢀ, Brꢀ, Iꢀ, N3
,
Fig. 2 Photograph of PbG (1%, in ethanol, G1–Pb2+ ¼ 1 : 1) selectively
detects Iꢀ in the presence of various anions (5 equiv.), from left to right
and top to bottom are free PbG, PbG + AcOꢀ, HSO4ꢀ, H2PO4ꢀ, Fꢀ, Clꢀ,
Brꢀ, Iꢀ, N3ꢀ, SCNꢀ, ClO4ꢀ, CNꢀ, CO32ꢀ, S2ꢀ and SO42ꢀ, respectively,
on a spot plate under UV at 365 nm.
Scheme 1 The synthetic route of organogelator G1.
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Fig. 5 Writing, erasing and coloration of a natural light invisible image
on a PbG supramolecular gel film (obtained from 1% ethanol metal-
logel, PbG, G1–Pb2+ ¼ 1 : 1. Writing: write in Iꢀ water solution; erasing:
brush Pb2+ water solution; coloration: expose the PbG film into the
iodine vapor ca. 5 s). The photographs were taken at room tempera-
ture under room light and exposed to a 365 nm UV light.
carried out. First, in the concentration dependent 1H NMR of G1
(Fig. 6), the –NH– (Hb) and –N]CH– (Ha) resonance signals
showed signicant downeld shis as the concentration of G1
rose. These results revealed that in the gelation process, the
–NH– (Hb) and –N]CH– (Ha) groups formed hydrogen bonds
with the –C]O groups on the adjacent gelators. On the other
hand, with a gradual increase in concentration, the 1H NMR
signal of phenyl protons (Hc, Hd, He, and Hf) showed an evident
upeld shi, indicating that the p–p stacking interactions
between the phenyl groups involved in the gelation process.61
Therefore, the gelator G1 self-assembled to supramolecular
organogel OG by the hydrogen bonds, p–p stacking as well as
the vdW existing in the long alkyl chains.
The formation mechanism of supramolecular metallogel
was also investigated by 1H NMR titrations, as shown in Fig. 7.
With the addition of Pb2+, the –NH– (Hb) group on the gelator
showed signicant downeld shis, which indicated that the
gelator coordinated with Pb2+ via the acylhydrazone moiety. In
addition, in the IR spectra (Fig. S5†) the stretching vibrations of
–C]O and –C]N– of G1 showed obviously shis from 3455
and 1650 cmꢀ1 to 3583 and 1588 cmꢀ1, respectively. These
phenomena indicated that in PbG, Pb2+ coordinated with the
nitrogen and oxygen atoms on the acylhydrazone group.
This presumed self-assembly and coordination mechanism
was also supported by the Tgel of OG and PbG. For instance, as
shown in Fig. 8, under the same condition, the Tgel of OG was
signicantly higher than that of PbG. The large differences of
Fig. 3 Fluorescence spectra of PbG (1%, in ethanol, G1–Pb2+ ¼ 1 : 1)
with increasing concentration of Iꢀ (using 1 mol Lꢀ1 TBA in water
solution as the Iꢀ sources), lex ¼ 340 nm.
make PbG act as an Iꢀ and Pb2+ controlled “on–off–on” uo-
rescent switch. By alternate addition of Iꢀ and Pb2+, the
switching could be performed reversibly at least for three cycles
with a small uorescent efficiency loss (Fig. 4).
In order to facilitate the use of the metallogel PbG, the Iꢀ
detection lm based on PbG was prepared by pouring the
heated ethanol solution of PbG onto a clean glass surface and
then drying in air. The PbG lm was white under natural light
and showed a blue uorescence emission under UV at 365 nm.
When a writing brush dipped in Iꢀ water solution was used to
write on the lm, the lm did not show any color changes.
However, under UV at 365 nm, a clear dark writing image
appeared (Fig. 5). This dark writing image could be erased by
brushing Pb2+ on the lm. More interestingly, when the PbG
lm containing the invisible Iꢀ writing was exposed to iodine
vapor, a clear brown writing appeared on the lm. However,
when the lm was put under the room atmosphere for one
minute, the brown writing disappeared gradually. Therefore,
the PbG lm could act as not only a convenient reversible Iꢀ
detection test kit, but also an erasable dual-channel security
display material.
In order to investigate the self-assembly and stimuli-
response mechanism of PbG, a series of experiments was
Fig. 4 Fluorescent “on–off–on” cycles of PbG, controlled by the Fig.
6
Partial 1H NMR spectra of G1 in CDCl3 with different
concentrations.
alternative addition of Iꢀ and Pb2+, lex ¼ 340 nm.
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Fig. 7 Partial 1H NMR spectra of G1 (2 mg mLꢀ1) and G1 mixed with 1–
7 equiv. of Pb2+ in ethanol-d6.
Scheme 2 Chemical structure of the G1 and the presumed self
assembly and reversible stimuli-response mechanism.
Tgel between OG and PbG were ascribed to the breakage of
intermolecular hydrogen bonds between –N]C–H on one
gelator and –C]O on the other one in OG, which was caused by
the coordination of Pb2+ with the gelator G1. Moreover, the Pb2+
coordination process reduced the distance of p–p stacking
between the phenyls, which enhanced the aggregation induced
emission of PbG.
Pb2+ and led to the recovery of XRD peaks. According to 1H
NMR, IR and XRD, the ion response mechanism of OG and PbG
could be presumed as in Scheme 2.
To get further insight into the morphological features of the
supramolecular organogel OG, metallogel PbG and PbG treated
with Iꢀ, SEM studies were carried out with their xerogels,
respectively. As shown in Fig. S7,† the SEM images of OG
showed an overlapped rugate layer structure. The metallogel
PbG also showed overlapped rugate layer structures and the
aggregation structure of layer was compacted. However, aer Iꢀ
was added into the PbG xerogel, the micro states experienced
obvious changes. There were a large number of micro cavities
formed in the xerogel of PbG. These micro cavities provided the
PbG xerogel with the properties for the adsorption of iodine
vapor. Therefore, the mechanism of iodine vapor-caused color
change could be attributed to the iodine vapor adsorption into
these micro cavities.
This proposed mechanism was also supported by the XRD
patterns (Fig. S6†). The XRD patterns of OG, PbG and the PbG
treated with Iꢀ showed the peaks at 2q ¼ 18.62–27.70ꢂ, corre-
˚
˚
˚
sponding to the d spacing 3.5 A, 3.45 A, and 3.8 A, respectively.
As shown in Scheme 2 and Fig. S6,† in OG, the peaks at 21.28ꢂ
˚
and the d spacing 3.5 A were attributed to the p–p stacking,
which existed in the phenyl groups of OG. While, in PbG, the
2+
˚
d spacing changed to 3.45 A, which was attributed to the Pb
coordination process reducing the distance of p–p stacking
˚
between the phenyls. Meanwhile, the d spacing 3.8 A was
attributed to the interlamellar spacing between the supramo-
lecular chains. In addition, aer the formation of PbG, the
peaks of OG (at 2q ¼ 21.28, 23.22, 23.90, 25.30ꢂ) disappeared
and these peaks reappeared aer PbG was treated with Iꢀ. These
phenomena conrmed that Pb2+ coordinated with OG and
induced a change in the XRD pattern of OG, while the addition
of Iꢀ into PbG induced the competitive coordination of Iꢀ with
4. Conclusions
In summary, a novel supramolecular gelator G1 has been
designed and synthesized. The gelator G1 could form a stable
supramolecular metallogel PbG. Through the competitive
coordination of Pb2+ and Iꢀ with the gelator G1, the
aggregation-induced emission of the supramolecular metal-
logel PbG was controlled as “on–off–on”. More interestingly,
aer Pb2+ competitive coordinated with Iꢀ, there were a large
number of micro cavities formed in the PbG xerogel, which
enabled the PbG xerogel to absorb the iodine vapor and show
a brown color. PbG could act as not only a convenient high
selective and sensitive Iꢀ detection test kit, but also an erasable
dual-channel secret documentation medium.
Acknowledgements
This study was supported by the National Natural Science
Foundation of China (NSFC) (No. 21662031; 21661028;
21574104; 21262032) and the Program for Changjiang Scholars
Fig. 8 Plots of Tgel against the concentrations of organogel OG and
metallogels PbG (G1–Pb2+ ¼ 1 : 1) in ethanol.
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and Innovative Research Team in University of Ministry of 26 Y. Cao, X. Y. Hu, Y. Li, X. Zou, S. Xiong, C. Lin, Y. Z. Shen and
Education of China (IRT 15R56).
L. Wang, J. Am. Chem. Soc., 2014, 136, 10762.
27 N. V. V. Satya Bhushan and R. N. Nayak, J. Oral Maxillofac.
Surg., 2010, 9, 119.
28 J. A. Foster, K. K. Damodaran, A. Maurin, G. M. Day,
H. P. G. Thompson, G. J. Cameron, J. C. Bernal and
J. W. Steed, Chem. Sci., 2017, 8, 78.
Notes and references
1 M. D. Segarra-Maset, V. J. Nebot, J. F. Miravet and B. Escuder,
Chem. Soc. Rev., 2013, 42, 7086.
2 H. Tan, X. Ma and M. Fu, Bull. Mater. Sci., 2013, 36, 153.
3 L. Predoana, I. Stanciu, M. Anastasescu, J. M. Calderon-
29 H. Wang, X. Ji, Z. Li, C. N. Zhu, X. Yang, T. Li, Z. L. Wu and
F. Huang, Materials Chemistry Frontiers, 2017, 1, 167.
Moreno, M. Stoica, S. Preda, M. Gartner and M. Zaharescu, 30 P. Hallegot, G. Hussler, V. Jeanne-Rose, F. Leroy, F. Pineau
J. Sol-Gel Sci. Technol., 2016, 78, 589.
and H. Samain, J. Sol-Gel Sci. Technol., 2016, 79, 365.
4 Z. X. Liu, Y. Feng, Z. C. Yan, Y. M. He, C. Y. Liu and Q. H. Fan, 31 S. Lee and S. T. Nguyen, Macromolecules, 2013, 46, 9169.
Chem. Mater., 2012, 24, 3751.
5 Q. Xia, Y. Mao, J. Wu, T. Shu and T. Yi, J. Mater. Chem. C,
2014, 2, 1854.
6 S. Basak, J. Nanda and A. Banerjee, Chem. Commun., 2014,
50, 2356.
32 P. Xue, Q. Xu, P. Gong, C. Qian, A. Ren, Y. Zhang and R. Lu,
Chem. Commun., 2013, 49, 5838.
33 T. Ghane, D. Nozaki, A. Dianat, A. Vladyka, R. Gutierrez,
J. P. Chinta, S. Yitzchaik, M. Calame and G. Cuniberti, J.
Phys. Chem. C, 2015, 119, 6344.
7 A. S. Lee, S. S. Choi, K. Y. Baek and S. S. Hwang, Inorg. Chem. 34 N. Song, D. X. Chen, Y. C. Qiu, X. Y. Yang, B. Xu, W. Tian and
Commun., 2016, 73, 7.
Y. W. Yang, Chem. Commun., 2014, 50, 8231.
8 S. S. Babu, V. K. Praveen and A. Ajayaghosh, Chem. Rev., 2014, 35 X. Yan, D. Xu, X. Chi, J. Chen, S. Dong, X. Ding, Y. Yu and
114, 1973.
F. Huang, Adv. Mater., 2012, 24, 362.
9 V. Lozano, R. Hernandez, A. Arda, J. Jimenez-Barbero, 36 Y. M. Zhang, B. B. Shi, H. Li, W. J. Qu, G. Y. Gao, Q. Lin,
´
´
´
´
´
C. Mijangos and M. J. Perez-Perez, J. Mater. Chem., 2011,
21, 8862.
H. Yao and T. B. Wei, Polym. Chem., 2014, 5, 4722.
37 Q. Lin, B. Sun, Q. P. Yang, Y. P. Fu, X. Zhu, T. B. Wei and
Y. M. Zhang, Chem.–Eur. J., 2014, 20, 11457.
38 K. Lalitha, V. Sridharan, C. U. Maheswari, P. K. Vemula and
S. Nagarajan, Chem. Commun., 2017, 53, 1538.
10 Y. He, Z. Guo, P. Jin, C. Jiao, H. Tian and W. Zhu, Ind. Eng.
Chem. Res., 2015, 54, 2886.
11 C. D. Jones and J. W. Steed, Chem. Soc. Rev., 2016, 45, 6546.
12 P. Xue, J. Ding, M. Jin and R. Lu, J. Mater. Chem. C, 2017, 5, 39 Y. Zhang, B. Zhang, Y. Kuang, Y. Gao, J. Shi, X. X. Zhang and
5299.
B. Xu, J. Am. Chem. Soc., 2013, 135, 5008.
13 Q. Duan, Y. Cao, Y. Li, X. Hu, T. Xiao, C. Lin, Y. Pan and 40 S. S. Abolmaali, A. Tamaddon, H. Naja and R. Dinarvand, J.
L. Wang, J. Am. Chem. Soc., 2013, 135, 10542. Inorg. Organomet. Polym., 2014, 4, 977.
14 G. Visioli, A. Comastri, D. Imperiale, G. Paredi, A. Faccini 41 Q. Lin, T. T. Lu, X. Zhu, B. Sun, Q. P. Yang, T. B. Wei and
and N. Marmiroli, Food Anal. Methods, 2016, 9, 469. Y. M. Zhang, Chem. Commun., 2015, 51, 1635.
15 J. Jielile, A. Jialili, G. Sabirhazi, N. Shawutali, D. Redati, 42 Q. Lin, T. T. Lu, J. C. Lou, G. Y. Wu, T. B. Wei and
J. Chen, J. Bai and K. Aldyarhan, Appl. Biochem. Biotechnol.,
2012, 166, 521.
16 Y. Cao, Y. Li, X. Y. Hu, X. Zou, S. Xiong, C. Lin and L. Wang,
Chem. Mater., 2015, 27, 1110.
17 J. Zhou, X. Du, Y. Gao, J. Shi and B. Xu, J. Am. Chem. Soc.,
2014, 136, 2970.
18 G. Sun, J. Xiao, M. Lu, H. Wang, X. Chen, Y. Yu, Y. Pan and
Y. Wang, Appl. Biochem. Biotechnol., 2015, 175, 400.
Y. M. Zhang, Chem. Commun., 2015, 51, 12224.
43 Q. Lin, Q. P. Yang, B. Sun, J. C. Lou, T. B. Wei and
Y. M. Zhang, RSC Adv., 2015, 5, 11786.
44 Q. Lin, F. Zheng, L. Liu, P. P. Mao, Y. M. Zhang, H. Yao and
T. B. Wei, RSC Adv., 2016, 6, 11928.
45 Q. Lin, P. P. Mao, L. Liu, J. Liu, Y. M. Zhang, H. Yao and
T. B. Wei, RSC Adv., 2017, 7, 11206.
46 M. H. Liu and Y. Fang, Chin. Sci. Bull., 2012, 57, 4245.
19 T. Kitahara, M. Shirakawa, S. Kawano, U. Beginn, N. Fujita 47 C. Zhao, X. Zhang, K. Li, S. Zhu, Z. Guo, L. Zhang, F. Wang,
and S. Shinkai, J. Am. Chem. Soc., 2005, 127, 14980.
20 X. Y. Hu, T. Xiao, C. Lin, F. Huang and L. Wang, Acc. Chem.
Res., 2014, 47, 2041.
21 G. Mun, H. Choi, N. Im, J. Ahn, J. Park, H. Seo, Y. Choi,
J. H. Lee and J. H. Jung, RSC Adv., 2017, 7, 26827.
22 C. Kim, K. Y. Kim, J. H. Lee, J. Ahn, K. Sakurai, S. S. Lee and
J. H. Jung, ACS Appl. Mater. Interfaces, 2017, 9, 3799.
23 E. P. Simonenko, A. V. Derbenev, N. P. Simonenko,
Q. Fei, S. Luo, P. Shi, H. Tian and W. H. Zhu, J. Am. Chem.
Soc., 2015, 137, 8490.
48 Q. Lin, Q. P. Yang, B. Sun, Y. P. Fu, X. Zhu, T. B. Wei and
Y. M. Zhang, So Matter, 2014, 10, 8427.
49 Y. Gong, T. Jiao, Q. Hu, N. Cheng, W. Xu, Y. Bi and L. Yu, J.
Phys. Chem. C, 2015, 119, 16349.
50 X. Ji, Y. Yao, J. Li, X. Yan and F. Huang, J. Am. Chem. Soc.,
2013, 135, 74.
V. G. Sevastyanov and N. T. Kuznetsov, Russ. J. Inorg. 51 Q. Lin, B. Sun, Q. P. Yang, Y. P. Fu, X. Zhu, Y. M. Zhang and
Chem., 2015, 60, 1444.
T. B. Wei, Chem. Commun., 2014, 50, 10669.
24 Z. Cheng, J. Liao, B. He, F. Zhang, F. Zhang, X. Huang and 52 D. H. Qu, Q. C. Wang, Q. W. Zhang, X. Ma and H. Tian, Chem.
L. Zhou, ACS Sustainable Chem. Eng., 2015, 3, 1677. Rev., 2015, 115, 7543.
25 M. Jiang, J. Zhu, C. Chen, Y. Lu, Y. Ge and X. Zhang, ACS 53 Y. Hong, J. W. Y. Lam and B. Z. Tang, Chem. Soc. Rev., 2011,
Appl. Mater. Interfaces, 2016, 8, 3473.
40, 5361.
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54 W. Lei, Y. Liu, J. Bai, Y. Dai, Y. Kan, T. Chen and B. Yin, 58 N. Tamaoki, A. V. Parfenov, A. Masaki and H. Matsuda, Adv.
Tetrahedron, 2015, 71, 5465. Mater., 1997, 9, 1102.
55 K. Duraimurugan, J. Sivamani, M. Sathiyaraj, V. Thiagarajan 59 Y. P. Fu, Q. Lin, T. B. Wei, P. Chen, X. Zhu, X. Liu and
and V. Siva, J. Fluoresc., 2016, 26, 1211. Y. M. Zhang, Chem. Reagents, 2013, 35, 367.
56 X. Wu, H. Li, Y. Kan and B. Yin, Dalton Trans., 2013, 42, 60 Analytical Methods Committee, Analyst, 1987, 112, 199.
16302.
61 C. Po, Z. Ke, A. Y. Y. Tam, H. F. Chow and V. W. W. Yam,
57 A. Kishimura, T. Yamashita, K. Yamaguchi and T. Aida, Nat.
Mater., 2005, 4, 546.
Chem.–Eur. J., 2013, 19, 15735.
This journal is © The Royal Society of Chemistry 2017
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