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. 2020 Aug 19;5(34):21684–21688. doi: 10.1021/acsomega.0c02589

A Simple Water-Soluble ESIPT Fluorescent Probe for Fluoride Ion with Large Stokes Shift in Living Cells

Xu Liu †, Xin Liu †, Youming Shen †,*, Biao Gu ‡,*
PMCID: PMC7469414  PMID: 32905448

Abstract

graphic file with name ao0c02589_0008.jpg

Developing an effective method for monitoring fluoride ion in biological samples is meaningful because fluoride ion plays a vital role in biological processes. In this contribution, a simple water-soluble ESIPT fluorescent probe 2-((4-((tert-butyldiphenylsilyl)oxy)-1,3-dioxoisoindolin-2-yl)methyl)-1-ethylpyridin-1-ium iodide (SPI) was constructed for monitoring fluoride ion. The probe SPI containing pyridinium salt group exhibited preeminent water solubility. The probe SPI introducing a trimethyldiphenylsilyl ether recognition group displayed excellent selectivity for fluoride ion over other biologically relevant species. Additionally, the probe SPI exhibited a fast response for a fluoride ion, suggesting that it could provide real-time fluoride ion detection. Importantly, the probe could detect fluoride ion with a linear range of 0–70.0 × 10–6 M and a low detection limit of 1.16 × 10–6 M. Furthermore, probe SPI could detect fluoride ion with a large Stokes shift (98 nm), which was attributed to ESIPT fluorescence sensing process. At last, probe SPI was successfully employed to monitor fluoride ion in living cells.

1. Introduction

As the smallest anion, fluoride ion (F–) is an indispensable and important anion in the treatment of osteoporosis and dental health.1 It is widely used as an additive in pharmaceutical agents, toothpaste, and drinking water.2,3 However, excessive ingestion can cause skeleta fluorosis, dental, nephrolithiasis, osteosarcoma, and metabolic dysfunctions.3−5 Accordingly, the detection of fluoride ion is particularly meaningful in environmental samples and biological systems.

To date, several methods for detecting fluoride ion have been developed, such as spectrophotometry,6,7 electrochemical method,819F NMR,9 high-performance liquid chromatography (HPLC),10 and ion chromatography.11 Even though the above detection techniques could monitor fluoride ion with excellent selectivity and sensitivity, they were not suitable for living biosystems owing to the need for destruction of cells or tissues. In contrast, fluorescent probes are recognized as ideal tools for the detection of fluoride ion by taking advantage of their high spatiotemporal resolution, real-time imaging capacity, nondestructive detection, and simplicity, which have attracted a lot of attention.12−25 Currently, a lot of fluorescent probes for fluoride ion have been fabricated, such as using the H-bond interactions,26−28 the interactions between F– and Lewis acids,29−31 and Si–O bond cleavage.32−34 However, for probes based on the first two mechanisms, they suffered from unsatisfactory selectivity or irreversibility.35−3735−37 Although desilylation-based probes for fluoride ion could overcome the above disadvantages, most of them could only need a high level of organic solvents or monitor tetrabutylammonium fluoride in organic solvents. Additionally, most of these reported had long reaction time or required cationic surfactant, cetyltrimethylammonium bromide (CTAB), to increase the reaction rate, which greatly restricted their practical application. Moreover, most of the fluoride ion fluorescent probes were developed with a small Stokes shift. The probes with a small Stokes shift was difficult to use for quantitative determination due to the interference of excitation light and self-absorption of fluorescence. Therefore, high specificity, fast response, and water-soluble fluorescent probes with large Stokes shifts are urgently required for fluoride ion.

As an ESIPT fluorophore, 3-hydroxyphthalimide derivatives have attracted attention owing to their characteristics including simple structure, good photostability, extremely facile chemical modification, and large Stokes shift.38 Herein, we synthesized a new ESIPT-based fluorescent probe for fluoride ion in which 4-hydroxy-2-(pyridin-2-ylmethyl)isoindoline-1,3-dione was utilized as the fluorophore and a trimethyldiphenylsilyl ether was used as the recognition group (Scheme 1). The trimethyldiphenylsilyl ether was selected as a recognition unit of fluoride ion due to its high specificity for fluoride ion. The introduction of pyridinium salt could not only achieve fast reaction rate but also enhance the solubility in water. The probe 2-((4-((tert-butyldiphenylsilyl)oxy)-1,3-dioxoisoindolin-2-yl)methyl)-1-ethylpyridin-1-ium iodide (SPI) was a weak fluorescent, in which the protection of hydroxyl group with trimethyldiphenylsilyl ether blocked the ESIPT process. However, fluoride ion could cleave the trimethyldiphenylsilyl ether group, releasing the fluorophore; thus, the fluorescence appeared. The probe SPI displayed many advantages including high selectivity, fast response, excellent water solubility, and large Stokes shift. Moreover, the probe SPI could be used for fluoride ion imaging in living cells.

Scheme 1. Proposed Detection Mechanism of SPI for F–

Scheme 1

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2. Results and Discussion

2.1. Spectral Properties of SPI to F–

To demonstrate the capability of SPI for F–, the spectra of SPI (10 μM) to F– were examined in phosphate-buffered saline (PBS) solution (20 mM, pH 7.4, containing 1% CH3CN). As shown in Figure S1A, in the absence of F–, the probe SPI displayed an absorption at 330 nm and the solution was colorless to the naked eye. Upon addition of F–, the ultraviolet–visible (UV–vis) absorption spectra of probe SPI exhibited significant enhancement at 413 nm, which might be due to the release of hydroxy. We then studied the fluorescence spectra of probe SPI (10 μM) toward F– in PBS (20 mM, pH 7.4, and containing 1% CH3CN). As displayed in Figure S1B, the free probe SPI was weak fluorescence at 511 nm owing to the inhibition of the ESIPT process between the imid carbonyl oxygen and hydroxy. After the addition of F–, the fluorescent emission of the probe SPI was enhanced at 511 nm and the solution was green, which might due to the F–-triggered cleavage of trimethyldiphenylsilyl ether. Meanwhile, the fluorescence intensity of SPI at 511 nm gradually increased with the continuous addition of F– concentration (Figure 1). When 250.0 μM F– was added, the fluorescence intensity became saturated. Additionally, the fluorescence intensities at 511 nm had a linear relationship with the F– concentrations at 0–70.0 μM. The detection limitation of F– was calculated to be 1.16 × 10–8 M (3σ/k). More importantly, the probe SPI showed a large Stokes shift (98 nm). The results indicated that the probe SPI can monitor F– with excellent sensitivity.

Figure 1.

Figure 1

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(a) Fluorescence emission spectra of SPI (10.0 μM) upon the addition of concentrations of F– in PBS solution (20 mM, pH 7.4). (b) Fluorescence emission of SPI at 511 nm versus increasing F– concentrations F– (0–70 μM) in PBS solution (20 mM, pH 7.4, containing 1% CH3CN).

2.2. Selectivity Studies

The specificity selectivity is of importance for the chemosensor. Thus, to demonstrate the selectivity of SPI, the fluorescence response of SPI for biologically relevant species (F–, Cl–, Br–, I–, S2–, AcO–, SO32–, SO42–, CO32–, NO2–, NO3–, HPO42–, H2PO4–, SCN, and ClO3–) was examined in PBS solution (20 mM, pH 7.4, containing 1% CH3CN). As presented in Figure 2, the fluorescence emission of SPI at 511 nm displayed dramatic enhancement upon the addition of F–. While the fluorescence intensities had weak changes in other analyses of species. The results indicated that SPI had high selectively toward F– over other competitive species.

Figure 2.

Figure 2

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Fluorescence spectral (A) and intensity (B) changes of SPI (10 μM) with various analytes (250 μM) in PBS solution (20 mM, pH 7.4, containing 1% CH3CN): (1) none, (2) F–, (3) Cl–, (4) Br–, (5) I–, (6) S2–, (7) AcO–, (8) SO32–, (9) SO42–, (10) CO32–, (11) NO2–, (12) NO3–, (13) HPO42–, (14) H2PO4–, (15) SCN–, and (16) ClO3–.

2.3. Response Time

Next, time-dependent fluorescence variation of SPI was investigated by monitoring the fluorescence intensities changes at 511 nm in the absence and the presence of F– in PBS solution (20 mM, pH 7.4, containing 1% CH3CN). As depicted in Figure 3, the probe SPI itself had no fluorescence change with the prolonging time. Meanwhile, with the addition of F–, the fluorescent intensity of the probe SPI at 511 nm increased immediately and reached a maximal at about 8 min. The results indicated that SPI can serve as a fast response to F–.

Figure 3.

Figure 3

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Time-dependent fluorescence intensity changes of free SPI (10 μM) (a) and in the presence of F– (250 μM) (b) in PBS solution (20 mM, pH 7.4, containing 1% CH3CN).

2.4. pH Effect Studies

As pH is a critical parameter for evaluating the application of performance, the pH dependence of the probe SPI was examined before and after the addition of F– in PBS solution (20 mM, pH 7.4, containing 1% CH3CN). As shown in Figure 4, the probe SPI displayed a weak fluorescence and retained the negligible changes in the range of 2–12, which indicated that the probe SPI was stable over a wide pH range. However, upon treatment with F–, the fluorescence intensities of the probe SPI at 511 nm significantly increased in the pH range 4–7 and remained stable in the pH range 7–10. The results suggested that the probe SPI can be used for biological detection.

Figure 4.

Figure 4

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Fluorescence intensity of SPI (10 μM) alone (a) and in the presence of F– (b) under different pH values.

2.5. Proposed Sensing Mechanism

To validate the reaction mechanism of SPI toward F–, the proposed product PI from the reaction of SPI with F– was obtained and analyzed by 1H NMR spectra. As shown in Figure S5, there was difference from the 1H NMR spectroscopy of SPI. The methyl of trimethyldiphenylsilyl ether disappeared at around 1.16 ppm and the hydroxyl peak appeared at around 11.25 ppm in the spectra, which verified the release of hydroxyl and the separation of trimethyldiphenylsilyl ether. In addition, the mixture of PID with the addition of F– by high-resolution mass spectrometry (HRMS) spectra was investigated. As depicted in Figure S6, a mass peak at m/z 283.1084 [M]+ was observed, which agreed well with PI (calcd m/z 283.1083 [M]+). Those results suggested that the trimethyldiphenylsilyl ether in SPI could be cleavaged into the −OH group by F– and gave compound PI. The possible sensing mechanism is described in Scheme 1.

2.6. Cell Imaging

Next, we assessed the ability of SPI for the detection of F– by confocal fluorescence imaging. As shown in Figure S7, when SPI was incubated with the cells, no fluorescence was observed. However, the green fluorescence was observed when NaF was added. The results suggested that SPI can be applied to detect F– in living cells.

3. Conclusions

In summary, through the ESIPT process, we developed a simple water-soluble fluorescent probe toward fluoride ion by combining 4-hydroxy-2-(pyridin-2-ylmethyl)isoindoline-1,3-dione fluorophore and F– capturing group trimethyldiphenylsilyl ether together. In the absence of fluoride ion, the ESIPT process of the probe was blocked and displayed a weak emission. When the fluoride ion was present, the ESIPT process was recovered, which resulted in green fluorescence emission. Meanwhile, the probe had rapid response, high specificity and selectivity, a wide working pH range, and a large Stokes shift for the fluoride ion, which is suitable for detecting fluoride ion in the living cells.

4. Experimental Section

4.1. Materials and Instruments

4-Hydroxyisobenzofuran-1,3-dione, trimethyldiphenyl chlorosilicon, iodoethane, and pyridin-2-ylmethanamine were purchased from Energy Chemical. The other chemicals were analytical grade and bought commercially. Fluorescence data were recorded on a Shimadzu RF-5301PC luminescence spectrometer. UV–vis spectra were obtained on a Shimadu UV-2501PC spectrophotometer. HRMS was performed with an Agilent 6210 ESI/TOF/MS instrument. The NMR data were acquired on a Bruker Ascend-400 instrument.

4.2. Synthesis of Probe SPI

A mixture of SP (0.49 g, 1.0 mmol)39 and iodoethane (0.2 mL) in anhydrous CH3CN (5 mL) was stirred at 90 °C for 12 h. The mixture was filtered to give SPI (0.28 g, 67%) (Scheme 2). 1H NMR (400 MHz, CDCl3) δ (ppm): 9.53 (d, 2H, J = 6.4 Hz), 8.02 (d, 2H, J = 6.4 Hz), 7.75–7.73 (m, 4H), 7.48–7.45 (m, 2H), 7.42–7.37 (m, 5H), 7.30 (d, 1H, J = 8.4 Hz), 6.71 (d, 1H, J = 8.4 Hz), 5.10 (s, 2H), 5.08–5.03 (m, 2H), 1.72 (s, 3H), 1.16 (s, 9H). 13C NMR (100 MHz, CDCl3) δ (ppm): 167.2, 165.6, 156.1, 153.6, 144.9, 136.1, 135.4, 133.3, 131.4, 130.5, 128.1, 126.9, 118.8, 116.8, 57.2, 40.3, 26.3, 19.7, 17.4. HRMS calcd for C33H33N2IO3Si [M – I]+ 521.2260, found 521.2229.

Scheme 2. Synthesis Route of SPI.

Scheme 2

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4.3. Cell Imaging

The HepG2 cells were seeded in a 96-well plate and cultured with a fresh medium for 24 h. The cells were loaded with SPI (10 μM) for 30 min at 37 °C, washed with PBS for three times, and imaged. The probe SPI (10 μM) was pretreated with HepG2 cells and co-incubated for another 30 min, incubated with F– for another 30 min, then the cells were washed with PBS for three times, and imaged. Confocal fluorescence images were collected by a Leica TCS SP8 confocal microscope.

Acknowledgments

This research was supported by the National Natural Science Foundation of China (No. 21907026), the Natural Science Foundation of Hunan Provincial (2017JJ2195), and Scientific Research Fund of Hunan Provincial Education Department (18B369).

Supporting Information Available

The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsomega.0c02589.

  • Spectroscopic data, NMR, and MS spectra (PDF)

The authors declare no competing financial interest.

Supplementary Material

ao0c02589_si_001.pdf (402.2KB, pdf)

References

  1. Kleerekoper M. The role of fluoride in the prevention of osteoporosis. Endocrinol. Metab. Clin. North Am. 1998, 27, 441–452. 10.1016/S0889-8529(05)70015-3. [DOI] [PubMed] [Google Scholar]
  2. Li Y.; Zhang X.; Zhu B.; Yan J.; Xu W. A highly selective colorimetric and “off-on-off” fluorescent probe for fluoride ions. Anal. Sci. 2010, 26, 1077–1080. 10.2116/analsci.26.1077. [DOI] [PubMed] [Google Scholar]
  3. Horowitz H. S. The 2001 CDC recommendations for using fluoride to prevent and control dental caries in the United States. J. Public Health Dent. 2003, 63, 3–8. 10.1111/j.1752-7325.2003.tb03467.x. [DOI] [PubMed] [Google Scholar]
  4. Singh P. P.; Barjatiya M. K.; Dhing S.; Bhatngar R.; Kothari S.; Dhar V. Evidence suggesting that high Intake of fluoride provokes nephrolithiasis in tribal populations. Urol. Res. 2001, 29, 238–244. 10.1007/s002400100192. [DOI] [PubMed] [Google Scholar]
  5. Cittanova M.-L.; Lelongt B.; Verpont M.-C.; Geniteau-Legendre M.; Wahbe F.; Prie D.; Coriat P.; Ronco P. M. Fluoride ion toxicity in human kidney collecting duct cells. Anesthesiology 1996, 84, 428–435. 10.1097/00000542-199602000-00022. [DOI] [PubMed] [Google Scholar]
  6. Li H. B.; Xu X. R. Separation and determination of fluoride in plant samples. Talanta 1999, 48, 57–62. 10.1016/S0039-9140(98)00225-2. [DOI] [PubMed] [Google Scholar]
  7. Themelis D. G.; Tzanamvaras P. D. Simultaneous spectrophotometric determination of fluoride and monofluorophosphate ions in toothpastes using a reversed flow injection manifold. Anal. Chim. Acta 2001, 429, 111–116. 10.1016/S0003-2670(00)01271-X. [DOI] [Google Scholar]
  8. Čápka V.; Bowers C. P.; Narvesen J. N.; Rossi R. E. Determination of total fluorine in blood at trace concentration levels by the wickbold decomposition method with direct potentiometric detection. Talanta 2004, 64, 869–878. 10.1016/j.talanta.2004.03.066. [DOI] [PubMed] [Google Scholar]
  9. Hara H.; Huang C.-c. Buffer composition suitable for determining very low fluoride concentrations using a fluoride ion-selective electrode and its application to the continuous analysis of rain water. Anal. Chim. Acta 1997, 338, 141–147. 10.1016/S0003-2670(96)00432-1. [DOI] [Google Scholar]
  10. Xu X. R.; Li H. B.; Gu J. D.; Peng K. J. Determination of fluoride in water by reversed-phase high-performance liquid chromatography using F--La3+-alizarin complexone ternary complex. Chromatographia 2004, 59, 745–747. 10.1365/s10337-004-0312-y. [DOI] [Google Scholar]
  11. Thangavel S.; Dash K.; Dhavile S. M.; Chaurasia S. C.; Mukherjee T. Determination of traces of chloride and fluoride in H2SO4, H3PO4 and H3BO3 by in situ analyte distillation-ion chromatography. J. Chromatogr. A 2005, 1074, 229–233. 10.1016/j.chroma.2005.03.101. [DOI] [PubMed] [Google Scholar]
  12. Long L.; Huang M.; Wang N.; Wu Y.; Wang K.; Gong A.; Zhang Z.; Sessler J. L. A mitochondria-specific fluorescent probe for visualizing endogenous hydrogen cyanide fluctuations in neurons. J. Am. Chem. Soc. 2018, 140, 1870–1875. 10.1021/jacs.7b12545. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Li W.; Gong X. Y.; Fan X. P.; Yin S. L.; Su D. D.; Zhang X. B.; Yuan L. Recent advances in molecular fluorescent probes for organic phosphate biomolecules recognition. Chinese Chem. Lett. 2019, 30, 1775–1790. 10.1016/j.cclet.2019.07.056. [DOI] [Google Scholar]
  14. Yang M.; Fan J.; Du J.; Peng X. Small-molecule fluorescent probes for imaging gaseous signaling molecules: current progress and future implications. Chem. Sci. 2020, 11, 5127–5141. 10.1039/d0sc01482f. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Singh H.; Tiwari K.; Tiwari R.; Pramanik S. K.; Das A. Small molecule as fluorescent probes for monitoring intracellular enzymatic transformations. Chem. Rev. 2019, 119, 11718–11760. 10.1021/acs.chemrev.9b00379. [DOI] [PubMed] [Google Scholar]
  16. He X. J.; Xiong W.; Zhang L. L.; Xu C. C.; Fan J. Y.; Qian Y. N.; Wen J. S.; Ding F.; Shen J. L. ESIPT-based ratiometric fluorescent probe for highly selective and sensitive sensing and bioimaging of group IIIA ions in living cancer cells and zebrafish. Dyes Pigm. 2020, 174, 108059 10.1016/j.dyepig.2019.108059. [DOI] [Google Scholar]
  17. He X.; Chen H.; Xu C.; Fan J.; Xu W.; Li Y.; Deng H.; Shen J. Ratiometric and colorimetric fluorescent probe for hypochlorite monitor and application for bioimaging in living cells bacteria and zebrafish. J. Hazard. Mater. 2020, 388, 122029 10.1016/j.jhazmat.2020.122029. [DOI] [PubMed] [Google Scholar]
  18. He X.; Wu C.; Qian Y.; Li Y.; Ding F.; Zhou Z.; Shen J. Symmetrical bis-salophen probe serves as a selectively and sensitively fluorescent switch of gallium ions in living cells and zebrafish. Talanta 2019, 205, 120118 10.1016/j.talanta.2019.120118. [DOI] [PubMed] [Google Scholar]
  19. Sun M. X.; Liu H. J.; Su Y. Y.; Yang W. X.; Lv Y. Off/on amino-functionalized polyhedral oligomeric silsesquioxane-perylene diimides based hydrophilic luminescent polymer for aqueous fluoride ion detection. Anal. Chem. 2020, 92, 5294–5301. 10.1021/acs.analchem.9b05840. [DOI] [PubMed] [Google Scholar]
  20. Long L. L.; Han Y. Y.; Liu W. G.; Chen Q.; Yin D. D.; Li L. L.; Yuan F.; Han Z. X.; Gong A. H.; Wang K. Simultaneous discrimination of hypochlorite and single oxygen during sepsis by a dual-functional fluorescent probe. Anal. Chem. 2020, 92, 6072–6080. 10.1021/acs.analchem.0c00492. [DOI] [PubMed] [Google Scholar]
  21. Ali R.; Dwivedi S. K.; Mishra H.; Misra A. Imidazole-coumarin containing D-A type fluorescent probe: Synthesis photophysical properties and sensing behavior for F- and CN- anion. Dyes Pigm. 2020, 175, 108163 10.1016/j.dyepig.2019.108163. [DOI] [Google Scholar]
  22. Long L. L.; Yuan X. Q.; Cao S. Y.; Han Y. Y.; Liu W. G.; Chen Q.; Gong A. H.; Wang K. Construction of a fluorescent probe for selectively detecting singlet oxygen with a high sensitivity and large concentration range based on a two-step cascade sensing reaction. Chem. Commun. 2019, 55, 8462–8465. 10.1039/C9CC04300D. [DOI] [PubMed] [Google Scholar]
  23. Long L.; Cao S.; Jin B.; Yuan X.; Han Y.; Wang K. Construction of a novel fluorescent probe for on-site measuring hydrogen sulfide levels in food samples. Food Anal. Method 2019, 12, 852–858. 10.1007/s12161-018-01421-3. [DOI] [Google Scholar]
  24. Ou-Yang J.; Li Y. F.; Jiang W. L.; He S. Y.; Liu H. W.; Li C. Y. Fluorescence-guided cancer diagnosis and surgery by a zero cross-talk ratiometric near-infrared γ-glutamyltranspeptidase fluorescent probe. Anal. Chem. 2019, 91, 1056–1063. 10.1021/acs.analchem.8b04416. [DOI] [PubMed] [Google Scholar]
  25. Long L.; Han Y.; Yuan X.; Cao S.; Liu W.; Chen Q.; Wang K.; Han Z. A Novel ratiometric near-infrared fluorescent probe for monitoring cyanide in food samples. Food Chem. 2020, 331, 127359 10.1016/j.foodchem.2020.127359. [DOI] [PubMed] [Google Scholar]
  26. Zhou Y.; Zhang J. F.; Yoon J. Fluorescence and colorimetric chemosensors for fluoride-ion detection. Chem. Rev. 2014, 114, 5511–5571. 10.1021/cr400352m. [DOI] [PubMed] [Google Scholar]
  27. Wu Z.; Tang X. Visualizing fluoride ion in mitochondria and lysosome of living cells and in living mice with positively charged ratiometric probes. Anal. Chem. 2015, 87, 8613–8617. 10.1021/acs.analchem.5b02578. [DOI] [PubMed] [Google Scholar]
  28. Juanjuan S.; Linlin W.; Yangfeng H. Colorimetric, turn-on fluorescence detection of fluoride ions using simple indole-based receptors in living cells. Anal. Methods 2019, 11, 2585–2590. 10.1039/C9AY00206E. [DOI] [Google Scholar]
  29. Agou T.; Kobayash J.; Kawashima T. Tuning of the optical properties and lewis acidity of dibenzopnictogenaborins by modification on bridging main group elements. Inorg. Chem. 2006, 45, 9137–9144. 10.1021/ic061055q. [DOI] [PubMed] [Google Scholar]
  30. Kanagaraj K.; Pitchumani K. Highly selective “turn-on” fluorescent and colorimetric sensing of fluoride ion using 2-(2-hydroxyphenyl)-2,3-dihydroquinolin-4(1H)-one based on excited-state proton transfer. Chem. Asian J. 2014, 9, 146–152. 10.1002/asia.201300816. [DOI] [PubMed] [Google Scholar]
  31. Park S. H.; Kwon N.; Lee J. H.; Yoon J.; Shin I. Synthetic ratiometric fluorescent probes for detection of ions. Chem. Soc. Rev. 2020, 49, 143–179. 10.1039/C9CS00243J. [DOI] [PubMed] [Google Scholar]
  32. Hu W.; Zeng L.; Wang Y.; Liu Z.; Ye X.; Li C. A ratiometric two-photon fluorescent probe for fluoride ion imaging in living cells and zebrafish. Analyst 2016, 141, 5450–5455. 10.1039/C6AN00905K. [DOI] [PubMed] [Google Scholar]
  33. Yang Q.; Jia C.; Chen Q.; Du W.; Wang Y.; Zhang Q. A NIR fluorescent probe for the detection of fluoride ions and its application in in vivo bioimaging. J. Mater. Chem. B 2017, 5, 2002–2009. 10.1039/C6TB03193E. [DOI] [PubMed] [Google Scholar]
  34. Qiu B.; Zeng Y.; Hu R.; Chen L. Y.; Yu T. J.; Yang G. Q.; Li Y. Förster resonance energy-transfer-based ratiometric fluorescent indicator for quantifying fluoride ion in water and toothpaste. ACS Omega 2018, 3, 18153–18159. 10.1021/acsomega.8b03042. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Chen P. P.; Bai W.; Bao Y. Y. Fluorescent chemodosimeters for fluoride ions via silicon-fluorine chemistry: 20 years of progress. J. Mater. Chem. C 2019, 7, 11731–11746. 10.1039/C9TC04567H. [DOI] [Google Scholar]
  36. Hu R.; Feng J.; Hu D.; et al. A rapid aqueous fluoride ion sensor with dual output modes. Angew. Chem., Int. Ed. 2010, 49, 4915–4918. 10.1002/anie.201000790. [DOI] [PubMed] [Google Scholar]
  37. Kim D.; Singha S.; Wang T. In vivo two-photon fluorescent imaging of fluoride with a desilylation-based reactive probe. Chem. Commun. 2012, 48, 10243–10245. 10.1039/c2cc35668f. [DOI] [PubMed] [Google Scholar]
  38. Nakazono M.; Saita K.; Kurihara C.; Nanbu S.; Zaitsu K. Intramolecular energy transfer in 3-amino-N-(7-methoxy-4-methylcoumaryl)phthalimide. J. Photochem. Photobiol., A 2009, 208, 21–26. 10.1016/j.jphotochem.2009.07.028. [DOI] [Google Scholar]
  39. Kanosue K.; Ando S. Fluorescence emissions of imide compounds and end-capped polyimides enhanced by intramolecular double hydrogen bonds. Phys. Chem. Chem. Phys. 2015, 17, 30659–30669. 10.1039/C5CP05055C. [DOI] [PubMed] [Google Scholar]

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Supplementary Materials

ao0c02589_si_001.pdf (402.2KB, pdf)

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