Highly selective fluorescence turn-on determination of fluoride ions via chromogenic aggregation of a silyloxy-functionalized salicylaldehyde azine

Article abstract of DOI:10.1016/j.tetlet.2017.02.066

A novel fluorescent chemsensor TBS-protected salicylaldehyde azine (TSAA) for fluoride ion was developed based on aggregation-induced emission (AIE). The probe TSAA was prepared by the reaction of salicylaldehyde azine (SAA) with tert-butyldimethylsilyl chloride (TBS-Cl) via an unusual synthetic methodology and shows only non-emission. Upon treatment with fluoride in aqueous MeCN solution, the TBS protective group of probe TSAA was removed readily and the fluorescence of the probe was switched on, which resulted in a new fluorescence peak around 543?nm. The fluorescent intensity at 543?nm increases linearly with fluoride ion concentration in the range 1–50?μmol?L^?1. This proposed probe shows excellent selectivity toward fluoride ion over other common anions and cations.

Full text of DOI:10.1016/j.tetlet.2017.02.066

Accepted Manuscript
Highly selective fluorescence turn-on determination of fluoride ions via chro-
mogenic aggregation of a silyloxy-functionalized salicylaldehyde azine
Yun-Hui Zhao, Yubo Li, Yunfei Long, Zhihua Zhou, Zilong Tang, Keqin Deng,
Shaowei Zhang
PII:
S0040-4039(17)30245-9
DOI:
http://dx.doi.org/10.1016/j.tetlet.2017.02.066
TETL 48677
Reference:
Tetrahedron Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
14 January 2017
16 February 2017
21 February 2017
Please cite this article as: Zhao, Y-H., Li, Y., Long, Y., Zhou, Z., Tang, Z., Deng, K., Zhang, S., Highly selective
fluorescence turn-on determination of fluoride ions via chromogenic aggregation of a silyloxy-functionalized
salicylaldehyde azine, Tetrahedron Letters (2017), doi: http://dx.doi.org/10.1016/j.tetlet.2017.02.066
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Highly selective fluorescence turn-on
determination of fluoride ions via
chromogenic aggregation of a silyloxy-
functionalized salicylaldehyde azine
Leave this area blank for abstract info.
Yun-Hui Zhao*, Yubo Li, Yunfei Long, Zhihua Zhou*, Zilong Tang* , Keqin Deng, Shaowei Zhang

1
Tetrahedron Letters
journal homepage: www.els evier.com
Highly selective fluorescence turn-on determination of fluoride ions via chromogenic
aggregation of a silyloxy-functionalized salicylaldehyde azine
Yun-Hui Zhao*, Yubo Li, Yunfei Long, Zhihua Zhou*, Zilong Tang* , Keqin Deng, Shaowei Zhang
School of Chemistry and Chemical Engineering, Hunan University of Science and Technology, Xiangtan, Hunan, 411201, China
ARTICLE INFO
ABSTRACT
Article history:
Received
A novel fluorescent chemsensor TBS-protected salicylaldehyde azine (TSAA) for fluoride ion
was developed based on aggregation-induced emission (AIE). The probe TSAA was prepared by
the reaction of salicylaldehyde azine (SAA) with tert-butyldimethylsilyl chloride (TBS-Cl) via
an unusual synthetic methodology and shows only non-emission. Upon treatment with fluoride
in aqueous MeCN solution, the TBS protective group of probe TSAA was removed readily and
the fluorescence of the probe was switched on, which resulted in a new fluorescence peak
around 543 nm. The fluorescent intensity at 543 nm increases linearly with fluoride ion
concentration in the range 1–50 µmol L−1. This proposed probe shows excellent selectivity
toward fluoride ion over other common anions and cations.
Received in revised form
Accepted
Available online
Keywords:
fluorescent chemsensor
fluoride ion determination
salicylaldehyde azine
2009 Elsevier Ltd. All rights reserved.
aggregation-induced emission
TBS-protected salicylaldehyde azine
1
2
3
4
5
6
7
8
9
Developing new fluorescent anion sensors and probes is an
emerging research area of great importance due to the
important roles and potential applications in biological,
environmental and supramolecular sciences. Fluoride ion (F−),
the smallest anion, is of special biological significance in
preventing from dental cares and in treatment of osteoporosis.
[1] Whereas trace fluoride is regarded as an essential ingredient
31 nitrate and convert the binding into an optical signal.
32 However, there are some limitations associate with existing
33 sensing methods. For example, “turn-on” fluorescent anion
34 chemosensors for selective fluoride detection often require
[12]
35 complicated synthetic procedures.
In addition, the
36 fluorescence spectra of some probes can only be observed in
37 organic solvent and are non-emissive in aqueous solution,
38 which greatly limits their analytical application in
39 environmental detection. Therefore, easy to synthesis and
40 higher sensitivity “turn-on” fluorescent probe for fluoride are
41 still appealing.
[2]
in toothpaste and is essential for body growth. However, a
higher concentration of fluoride ion can lead to fluorosis,
10 which cause serious toxic to the biological tissue even to many
11 serious neurodegenerative diseases.
[3]
For example, in
12 molecular and cell biology system, an exceeded intake of NaF
42
Most reported fluorophores such as fluorescein or
13 can affect a number of essential cell-signaling components and
43 rhodamine dyes show much weaker emission in aggregate or
44 solid states compared to that in solutions because of
45 concentration- or aggregation-caused quenching effect,
[4]
14 influence normal cellular metabolism.
Moreover, a high
15 level of F− could also lead to ecological damage and result in
16 dental or skeletal fluorosis, even nephrotoxic changes and
17 urolithiasis in humans. [5] For above reasons, tremendous effort
18 has been devoted to the development of highly selective and
19 sensitive methodology for detection of fluorides, especially for
20 NaF in aqueous solution.
[13]
46 which makes fluoride determination challenging. Aggregation-
47 induced emission (AIE) phenomenons, which reported by
48 Tang et al. in the past decade, are an emerging class of
49 molecules displaying strong fluorescence in their aggregate or
50 solid states. [14] The novel and sensitive fluorescence ‘turn-on’
51 feature of the AIE fluorophores makes them potential building
52 blocks in fabrication of chemical sensors, anion sensors, as
53 well as a probe for detection fluoride. [15] However, research
54 work for the sensing of anions by the AIE effect, especially for
55 the ratiometric detection of fluoride in aqueous solution, is
56 very rare. [16]
21
Many methods have been developed to detect fluoride ion
[6]
22 including fluoride ion selective electrodes (ISE),
23 chromatography,
24 fluorimetry
ion
[7]
[8]
[9]
spectrophotometry,
HPLC
and
[10]
. Fluorescent chemosensors, however, are
25 becoming an important detection method for fluoride ion for
26 many reasons: high sensitivity and selectivity, low cost, easy
57 TBS is a common protecting group for alcohols and
58 phenols.[17] In addition, it can be easily deprotected by fluoride
59 ion. The extraordinary affinity of fluoride to silicon has been
60 claimed as the “driving force” of the reaction between silyl
27 detection, and especially suitability as a diagnostic tool for
[11]
28 biological concern.
Most of fluorescent fluoride screening
29 methodology have concentrated on receptors that differentiate
30 F− from other anions, such as chloride, bromide, carbonate or

2
Tetrahedron
113
61 ethers and fluoride ion. [18] Based on this particular affinity, a
A single crystal of TSAA (CCDC 1511881) is obtained by
62 few novel and sensitive methodologies have been developed to
114 slow evaporation of its MeCN solution, which enables further
115 confirmation of its molecular structure by crystallographic
116 analysis (Tables S1). The crystal is nearly non-emissive and
117 the image of a square crystal is given in figure 1.
[19]
63 determine the fluoride.
Kim and Swager developed a
64 fluoride-sensing approach based on the fluoride ion-triggered
[20]
65 formation of highly fluorescent coumarin.
Akkaya
66 synthesized bodipy derivatives with silyl-protected phenolic
118
SAA is a strong yellow fluorescent dye with maximal
67 functionalities, and detected fluoride concentrations both in
[21]
119 emission at 543 nm upon excitation at 354 nm (Figure 2a). It
120 can be observed that TSAA was a no fluorescent compound in
121 contrast to its parent molecule, SAA. The silylation of the
122 hydroxy group of SAA effectively quenches its fluorescence
123 emission. Dual spectroscopic changes are caused by release of
124 SAA through a fluoride-induced Si-O bond cleavage (Figure
125 2a, b).
68 solution and in a poly(methylmethacrylate) matrix.
Yang
69 reported a new approach for fluoride sensing based on
70 modulation of the excited-state intramolecular proton transfer
71 (ESIPT) process of 2-(2’-hydroxyphenyl)benzimidazole
[22]
72 (HPBI).
Li found that silyl-appended spiropyran dye could
73 be used for rapid and sensitive colorimetric detection of
74 fluoride ions. [23]
126
127
128
129
130
131
75
Herein, we combine the AIE effect of SAA and the
76 extraordinary affinity of fluoride to silicon to develope a novel
77 fluorogenic probe TSAA (Scheme 1), for the selective
78 determination of fluoride ion in aqueous MeCN solution. The
79 new chemosensor could selectively and ratiometric detect
80 fluoride in aqueous solution.
132
133
134 Fig. 2 (a) Fluorescence spectra of 10 µmol L−1 SAA and TSAA in 90%
135 (v/v) MeCN–H2O solution; (b) absorption spectra of 10 µmol L−1 SAA
136 and TSAA in 90% (v/v) MeCN–H2O solution.
81
82 Scheme 1 Synthesis of probe TSAA
137
TSAA is stable under ambient conditions, and is soluble in
83
SAA was synthesized according to the method reported by
138 common organic solvents, but insoluble in water. Figure S3 of
139 the Supporting Information showed the UV−vis absorption
140 spectra of free TSAA in different organic solvents, and one
141 could see that the free TSAA was colorless with a strong
142 absorption band at around 334 nm in either the polar or the
143 nonpolar organic solvent except DMF and DMSO, but no
144 obvious absorption could be observed in the longer
145 wavelength, reflecting that TSAA mainly existed as the silyl
146 protected form.
84 Xiang and Tong.[24] TSAA can’t be prepared by conventional
85 synthetic method. Initially, SAA and excessive amounts of
86 TBS-Cl were added into anhydrous THF under the presence of
87 imdazole. However, both mono-silyl and di-silyl were formed
88 as a inseparable mixture. Di-silyl compound also can’t be
89 obtained as single product in other solvent or under other
90 reaction conditions. After a series of screenings, triethylamine
91 (TEA) was used as a base and solvent to provide the single
92 target product. This phenonmenon maybe caused by the strong
93 intramolecular hydrogen-bond (Scheme 1). TSAA has some
94 special features in molecular design compared to most
95 conventional AIE fluorophores: (1) two salicylaldimine units
96 are connected by a rotatable N-N single bond rather than C-C
97 bond; (2) intramolecular hydrogen bonds of salicylaldimine
98 moieties and stacking of molecules in aggregate state inhibit
99 the free intramolecular rotation resulted in the reduced
147
148
149
150
151
152
153
154
100 attenuation of non-radioactive energy to trigger the
[24]
155
156
101 fluorescence “turn on”.
This probe TSAA shows a drastic
102 change in UV-vis absorption and fluorescence emission under
103 the presence of fluoride over other anions in CH3CN/H2O
104 (90:10, v/v). Because of the high affinity of fluoride for
105 silicon, TBS group was easily deprotected by fluoride (Figure
106 1).
157 Fig. 3 Effect of MeCN concentration (VMeCN/Vwater = 3936/64, 9/1, 8/2, 7/3,
158 6/4, 5/5, 4/6) on fluorescence intensity of TSAA (10 µmol L−1) in the
159 presence of fluoride ion
160
Nonaqueous reaction media was unfavorable for the
161 removal of silyl protecting group due to the poor solubility of
162 fluoride ion in organic solvents. Therefor, we tuned the
163 reaction conditions to the MeCN-H2O cosolvent mixtures.
164 Furthermore, the effect of MeCN concentration on
165 fluorescence intensity of the reaction system was studied, and
166 the results are shown in Fig. 3. It showed that fluorescence
167 intensity remains almost unchanged when MeCN
168 concentration is in the range 0–50%, and increases
169 dramatically when the concentration of MeCN is above 60%.
170 However, the fluorescence intensity was sharply decreased in
107
108
109
110
111
112 Fig. 1 TSAA transformed to SAA in the presence of fluoride ion

3
171 99% MeCN-H2O solution because of the poor solubility of F−.
172 To facilitate the real sample analysis, 90% MeCN-H2O
173 solution was selected as the reaction media in the following
174 experiment.
224 solution. The signal changes with increases in F− concentrations (0, 1, 2,
225 5, 10, 20, 50, 100, 200 µM). Fluorescent emission enhancement (I) of
226 TSAA at 543 nm as a function of the concentrations of F−. The
227 magnitudes of the error bars were calculated from the uncertainty given by
228 three independent measurements.
175
The effect of the reaction time on fluorescence intensity of
176 this system was studied and the results are shown in Fig. 4. It
177 can be seen that fluorescence intensity increased gradually
178 with increasing the reaction time, and the complete cleavage
179 of TBS group from the probe required about 2h under the
180 optimized reaction conditions. And the sensitivity of the
181 present method has almost no remarkable change with
182 increasing the incubation time. A 30-min reaction time was
183 selected as a compromise of sensitivity and analytical
184 frequency. Previous reports showed that fluoride ion
185 recognition process usually needed a few hours in aqueous
186 solution to complete the detection process due to the low
187 solubility of probe.
229
230 determined by examining the changes in the fluorescence
231 spectra of probe TSAA caused by other anions, such as Cl−,
The selectivity of the probe TSAA herein has been
232 Br−, IO3−, IO4 , NO3 , NO2−, Ac−, CO32−, SO42−, SO3 were
233 investigated. After the addition 1.0 equiv. of each of these
234 anions for 30min, the fluorescence spectra of solution TSAA
235 were measured and shown in Fig. 6a. It can be observed that
236 only fluoride gave dramatic changes in fluorescence spectra,
237 while other anions did not cause obvious changes under
238 identical conditions. The fluorescence peak at 543 nm
239 accompanied with remarkable color response from colorless to
240 yellow was found only in TSAA holding F− solution, and no
241 other anions caused observable color changes, which indicated
242 that the probe TSAA could selectively signal F− due to the
243 highly special affinity between fluorine and silicon.
−
−
2−
188
189
190
191
244
The effective applications of the probe caused by cations,
+
192
193
194
245 such as Ag+, Ba2+, Ca2+, Li+, Mg2+, NH4 , Ni2+, Zn2+ were also
246 studied. After the addition 1 equiv. of each of these anions for
247 30min, the fluorescence spectra of solution TSAA were
248 measured. Fig. 6b showed that the addition of these cations did
249 not result in any changes in the fluorescence spectrum. Other
250 fluoride were tested under the same condtions. As can be seen
251 in figure S5, CaF2, MgF2 and AlF3 did not result in either new
252 emission wavelengths or enhancement in fluorescence
253 intensity.
195
196 Fig. 4 (I) Reaction-time profile of TSAA (10 µmol L−1) in the absence a
197 and presence b of fluoride ion (2.0 µmol L−1). (II) The fluorescence
198 intensity were continuously monitored at time intervals.
199
To demonstrate the applicability of the proposed approach
200 for quantitative detection of F−, we measured the fluorescence
201 spectra of TSAA containing F− at varied concentrations under
202 the optimized experimental conditions. As shown in Fig. 5, the
203 TSAA exhibited non-emission in the absence of F−; however,
204 with the addition of F−, the emission around 543 nm gradually
205 increased. The fluorescence intensity was plotted as a function
206 of the fluoride concentration, and a typical calibration graph
207 was obtained. The fluorescence intensity (I) is linear with
208 fluoride concentration (c) in the range 1–50 µmol L−1 with a
209 correlation coefficient of R = 0.998 (n = 6). The linear
210 regression equation was determined to be I = 5.73c [µmol
211 L−1]+24.83 (n=6, R = 0.998). The detection limit was
212 determined from three times the standard deviation of the
213 blank signal as 0.81 µmol L−1. The relative standard deviation
214 (n = 6) was 1.7% for 10 µmol L−1 of fluoride ion.
254
255
256
257
258
259
CAT+=Hexadecyltrimethylammonium
260
261
262 Fig. 6 Fluorescent emission changes ( λex = 543 nm) of TSAA (10 µmol
263 L−1) upon addition of various (a) anions and (b) cations (10 µmol L−1) in
264 90% MeCN-H2O solution
1
To gain further insight of the reaction, we used H NMR
265
266 spectra to monitor the process of F- detection with TSAA in
267 CDCl3 and CD3OD before and after the addition of F−. As
268 shown in Fig. 7, TSAA exhibited one sharp peak around 9.0
269 ppm, corresponding to the signals of the N=CH
215
216
217
218
219
220
221
1
270 (salicylaldehyde hydrazone). There was no change in the H
271 NMR spectrum of TSAA under the UV light for 2h in the
272 absence of fluoride ion, which indicated the probe was stable
273 in CDCl3-CD3OD cosolvent in the absence of fluoride.
274 Nevertheless, when probe was reacted with fluoride ion in
o
275 50% CDCl3-CD3OD mixture at 60 C for 20 h, the signal of
276 the N=CH was gradually disappeared and 0.3 ppm upfield
277 shift, while a new peak at around 8.7 ppm emerged. This
278 phenomenon maybe caused by the intramolecular hydrogen
279 bond. The signal of the N=CH disappeared completely after
280 heating for 96 h. The peak of OH was not emerged maybe due
281 to the existence of CD3OD. And the slow reaction process was
222 Fig. 5 Fluorescent emission changes ( λex = 543 nm) of TSAA (10µmol
223 L−1) in the presence of increasing amounts of F− in 90% MeCN-H2O (v/v)

4
Tetrahedron
282 resulted by the trace solubility of fluoride ion in the CDCl3-
283 CD3OD mixture. The chemical shifts of TBS were also moved
284 slightly. Therefore, the result strongly supported the formation
285 of SAA from TSAA (Figure S4), including the removal of the
286 TBS and the recovery of the hydroxyl group, by attack of
287 fluoride.
337 [5] (a)Bowman-James, K. Acc. Chem. Res. 2005, 38, 671; (b)
338 Gale, P. A. Acc. Chem. Res. 2006, 39, 465; (c) Weatherall, J. A.
339 Pharmacology of Fluorides. In Handbook of Experimental
340 Pharmacology XX/1; Springer-Verlag: Berlin, Part 1, 1969, 141;
341 (d) Cittanova, M. L.; Lelongt, B.; Verpont, M. C. Anesthesiology,
342 1996, 84, 428; (e) Singh, P. P.; Barjatiya, M. K.; Dhing, S.;
343 Bhatnagar, R.; Kothari, S. Dhar, V. Urol. Res. 2001, 29, 238.
344 [6] (a) Capka, V.; Bowers, C. P.; Narvesen, J. N.; Rossi, R. E.;
345 Talanta 2004, 64, 869; (b) Ruiz-Payan, A.; Ortiz, M.; Duarte-
346 Gardea, M. Microchem. J. 2005, 1, 19; (c) Hutchinson, J. P.;
347 Evenhuis, C. J.; Johns, C.; Kazarian, A. A.; Breadmore, M. C.;
348 Macka, M.; Hilder, E. F.; Guijt, R. M.; Dicinoski, G. W.; Haddad,
349 P. R. Anal. Chem. 2007, 79, 7005.
350 [7] (a) Kalyakina, O. P.; Dolgonosov, A. M. J. Anal. Chem. 2003,
351 58, 951; (b) Thangavel, S.; Dash, K.; Dhavile, S. M.; Chaurasia,
352 S. C.; Mukherjee, T. J. Chromatogr. A 2005, 1074, 229.
353 [8] (a) Li, H. B.; Xu, X. R. Talanta 1999, 48, 57; (b) Themelis, D.
354 G.; Tzanavaras, P. D. Anal. Chim. Acta 2001, 429, 111.
355 [9] Xu, X. R.; Li, H. B.; Gu, J. D.; Peng, K. J. Chromatographia
356 2004, 59, 745.
288
289
290
291
292
293
294
295
296
297
298
299
300
301
357 [10] (a) Nishimoto, J.; Yamada, T.; Tabata, M. Anal. Chim. Acta
358 2001, 428, 201; (b) 21 Garrido, M.; Lista, A. G.; Palomeque, M.;
359 Band, B. S. F. Talanta 2002, 58, 849.
1
302 Fig. 7 The changes of H Chemical shift (ppm) under the presence of
303 fluoride with increasing of reaction time
360 [11] (a) Badugu, R.; Lakowicz, J. R.; Geddes, C. D. Sens.
361 Actuators B 2005, 104, 103; (b) 23 Cho, E. J.; Moon, J. W.; Ko, S.
362 W.; Lee, J. Y.; Kim, S. K.; Yoon, J.; Nam, K. C. J. Am. Chem.
363 Soc. 2003, 125, 12376; (c) 24 Zhou, G.; Cheng, Y.; Wang, L.;
364 Jing, X.; Wang, F. Macromolecules 2005, 38, 2148.
365 [12] (a) Jiang, X.; Vieweger, M. C.; Bollinger, J. C.; Dragnea, B.;
366 Lee, D. Org. Lett. 2007, 9, 3579; (b) Cao, J.; Zhao, C.; Feng, P.;
367 Zhang, Y.; Zhu, W. RSC Advances 2012, 2, 418.
368 [13] Thomas III, S. W.; Joly, G. D.; Swager, T. M. Chem. Rev.
369 2007, 107, 1339.
370 [14] Hong, Y.; Lam, J. W. Y.; Tang, B. Z. Chem. Soc. Rev. 2011,
371 40, 5361.
304
In this study, a novel fluorescent chemsensor TSAA
305 was synthesized and demonstrated as a fluorescent probe
306 for the sensitive and selective detection of fluoride ions
307 with significant enhancement of fluorescence intensity.
308 The signal transduction occurs via a fluoride-triggered Si-
309 O bond cleavage that results in the formation of an
310 intramolecular hydrogen bond imine compound SAA.
311 The probe TSAA features a ratiometric fluorescent
312 response to fluoride with a marked emission enhancement
313 and shows high selectivity for fluoride over other anions
314 and cations. It has the relatively wide linear ranges and
315 low detection limit for fluoride detection in an MeCN-
316 H2O solution. This simple and sensitive F- detection has
317 the potential to be a general detection method for fluoride
318 ion in an aqueous environment.
372 [15] Zhang, L.; Hu, W.; Yu, L.; Wang, Y. Chem. Commun. 2015,
373 51, 4298.
374 [16] (a) Turan, I. S.; Cakmak, F. P.; Sozmen, F. Tetrahedron Lett.
375 2014, 55, 456; (b) Bineci, M.; Bağlan, M.; Atılgan, S. Sens.
376 Actuators B 2016, 222, 315; (c) Jiang, G.; Liu, X.; Wu, Y.; Wang,
377 J.; Dong, X.; Zhang, G.; Li, Y.; Fan, X. RSC Adv. 2016, 6, 59400.
319 Acknowledgments
320
321 Natural Science Foundation of China (Nos. 21372070 and
322 21471052), the Hunan Provincial Education Department
323 Scientific Research Fund (No. 14k035) are gratefully
324 acknowledged.
The generous financial support from the National
378 [17] (a) Corey, E. J.; Snider, B. B. J. Am. Chem. Soc. 1972, 94,
379 2549; (b) Ranu, B. C.; Jana, U.; Majee, A. Tetrahedron Lett.
380 1999, 40, 1985; (c) Sartori, G.; Ballini, R.; Bigi, F.; Bosica, G.;
381 Maggi, R.; Righi, P. Chem. Rev. 2004, 104, 199.
382 [18] Yang, X. Spectrochimica Acta Part A 2007, 67, 321.
383 [19] Kim, S. Y.; Hong, J. I. Org. Lett. 2007, 9, 3109.
384 [20] Kim, T.-H.; Swager, T. M. Angew. Chem. Int. 2003, 42,
385 4803.
386 [21] Bozdemir, O. A.; Sozmen, F.; Buyukcakir, O.; Guliyev, R.;
387 Cakmak, Y.; Akkaya, E. U. Org. Lett. 2010, 12, 1400.
388 [22] Yang, X.; Qi, H.; Wang, L.; Su, Z.; Wang, G. Talanta 2009,
389 80, 92.
325 Supplementary data
326
Supplementary data associated with this article can be
327 found, in the online version, at
328 References and notes
329 [1] (a) Farley, J. R.; Wergedal, J. E.; Baylink, D. J. Science 1983,
330 222, 330; (b) Kleerekoper, M. Endocrinol. Metab. Clin. North
331 Am. 1998, 27, 441; (c) Lennon, M. A. Bull. W.H.O. 2006, 84, 759.
332 [2] Horowitz, H. S. J. Public Health Dent. 2003, 63, 3.
333 [3] Kirk, K. L. Biochemistry of the Elemental Halogens and
334 Inorganic Halides, Plenum Press, New York, 1991, 58.
335 [4] Barbier, O.; Arreola-Mendoza, L.; Del Razo, L. M. Chem.-
336 Biol. Interact. 2010, 188, 319.
390 [23] Li, Y.; Duan, Y.; Zheng, J.; Li, J.; Zhao, W.; Yang, S.; Yang,
391 R. Anal. Chem. 2013, 85, 11456.
392 [24] Tang, W.; Xiang, Y.; Tong, A. J. Org. Chem. 2009, 74, 2163.
393

1. Highly sensitive and selective methodology for detection of fluoride ions
2. A fluorescence ‘turn-on’ probe under the presence fluoride ions
3. A ratiometric detection of fluoride in aqueous solution