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the AIE mechanism, and the substructure of the nanoparticles
formed was considered to be very crucial. 1ÁH2PO4 was also proven
À
to be applicable for ClO4 imaging in live cells. Our work demon-
strated that AIE might be an efficient strategy for the challenging
anion recognition in competitive solvents such as water.
The financial support for this work from the NSFC (No.
21172159, 21025205 and 21321061) and the NCET-13-0384 is
greatly appreciated.
Fig. 4 (a) Fluorescence spectra of 1ÁH2PO4 (25 mM) in the presence of the
sodium salts of different anions (SO42À, AcOÀ, NO3À, HCO3À, ClÀ, BrÀ and
IÀ), KF and LiClO4Á3H2O (15 equiv.) in 10 mM HEPES buffer (pH = 7.4), Notes and references
excited at 355 nm; (b) the corresponding fluorescence variations of 1Á
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(10 equiv.) in HEPES buffer under UV light.
fluorescence and gave a 14.4-fold enhancement. Small but unnotice-
2À
able variation was induced by SO4 and IÀ. The other anions did
´
´˜
´
2 For reviews: (a) M. E. Moragues, R. Martınez-Manez and F. Sancenon,
Chem. Soc. Rev., 2011, 40, 2593; (b) L. E. Santos-Figueroa, M. E. Moragues,
not cause any change at all. The fluorescence difference could also
be easily distinguished by the naked eye under UV light (Fig. 4b,
inset). Therefore, 1ÁH2PO4 could be used as a highly selective
´
´˜
´
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fluorescent sensor for ClO4 in aqueous solution. To the best of
our knowledge, 1ÁH2PO4 is the first fluorescence ‘‘turn-on’’ sensor
for ClO4 in water.16 The DLS experiment revealed that the nano-
À
particles were formed in the presence of ClO4À and the average size
was around 586 nm (PdI = 0.473, Fig. S6b, ESI†).
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living cells. When HeLa cells were incubated with 1ÁH2PO4 (25 mM) in
PBS buffer for 30 min at 37 1C, only faint luminescence was observed
in the cells by using the confocal luminescence microÀscopy (Fig. 5b).
After the cells were subsequently incubated with ClO4 (15 equiv.) at
37 1C for another 15 min, a strong blue fluorescence in the cytoplasm
was clearly seen (Fig. 5d). The bright-field images (Fig. 5a and c)
showed that the cells were alive during the incubation period. These
results demonstrated that 1ÁH2PO4 could penetrate the cell wall and
´
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À
be used for intracellular ClO4 imaging in vitro.
In conclusion, the first AIE active monoimidazolium skeleton 1
was synthesized. 1ÁI could serve as a highly selective fluorescence
À
turn-on sensor for H2PO4 in MeCN. More notably, 1ÁH2PO4
represented the first highly selective and fluorescence turn-on sensor
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Fig. 5 (a) Bright-field and (b) fluorescence images of the HeLa cells
cultured in the presence of 1ÁH2PO4 (25 mM) in PBS buffer at 37 1C for
30 min; (c) bright-field and (d) fluorescence images after incubation with
LiClO4Á3H2O (15 equiv.) for another 15 min.
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Chem. Commun., 2014, 50, 5623--5625 | 5625