Single sensor for multiple analytes in different optical channel: Applying for multi-ion response modulation

Article abstract of DOI:10.1016/j.saa.2017.04.026

A Schiff-base, (2,4-di-tert-butyl-6-((2-hydroxyphenyl-imino)-methyl)phenol) (L), has been improved to function as a simultaneous multi-ion probe in different optical channel. The probe changes from colorless to orangish upon being deprotonated by F^?, while the presence of Al³⁺ significantly enhances the fluorescence of the probe due to the inhibition of C[dbnd]N isomerization, cation-induced inhibition of excited-state intramolecular proton transfer (ESIPT), and chelation enhanced fluorescence (CHEF). Dual-channel “off-on” switching behavior resulted from the sequential input of F^? and Al³⁺, reflecting the balance of independent reactions of Al³⁺ and F^? with L and with one another. This sensing phenomenon realizes transformation between multiple states and beautifully mimics a “Write-Read-Erase-Read” logic circuit with two feedback loops.

Full text of DOI:10.1016/j.saa.2017.04.026

Accepted Manuscript
Single sensor for multiple analytes in different optical channel:
Applying for multi-ion response modulation
Chunshuang Liang, Shimei Jiang
PII:
S1386-1425(17)30291-3
doi: 10.1016/j.saa.2017.04.026
SAA 15079
DOI:
Reference:
Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy
To appear in:
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Revised date:
Accepted date:
2 February 2017
12 April 2017
16 April 2017
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ACCEPTED MANUSCRIPT
Single sensor for multiple analytes in different optical
channel: applying for multi-ion response modulation
Chunshuang Liang and Shimei Jiang*
State Key Laboratory of Supramolecular Structure and Materials, Jilin University,
2
699 Qianjin Avenue, Changchun 130012,P. R. China.
*
Corresponding author: Shimei Jiang
E-mail: smjiang@jlu.edu.cn
Tel: +86-431-85168474
Fax: +86-431-85193421
1

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Abstract
A Schiff-base, (2,4-di-tert-butyl-6-((2-hydroxyphenyl-imino)-methyl)phenol) (L), has
been improved to function as a simultaneous multi-ion probe in different optical
channel. The probe changes from colorless to orangish upon being deprotonated by F‾,
3
+
while the presence of Al significantly enhances the fluorescence of the probe due to
the inhibition of C=N isomerization, cation-induced inhibition of excited-state
intramolecular proton transfer (ESIPT), and chelation enhanced fluorescence (CHEF).
Dual-channel “off-on” switching behavior resulted from the sequential input of F‾ and
3
+
3+
Al , reflecting the balance of independent reactions of Al and F‾ with L and with
one another. This sensing phenomenon realizes transformation between multiple
states and beautifully mimics a “Write-Read-Erase-Read” logic circuit with two
feedback loops.
Keywords: multiple analytes, fluoride, aluminum ion, dual-channel, reversible,
multi-state logic circuit.
2

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1
. Introduction
Many molecular logic circuits have been developed on the basis of special
recognition effects due to the importance of cation and anion detection and its
potential application in information storage[1-11]. Designing sensors for multiple
analytes recognition is emerging an interesting area, because of the advantages such
as faster analytical processing and potential cost reductions[12-18]. Usually, multiple
analytes can be detected either by sequential or simultaneous recognition. Sequential
recognition of two analytes, such as one cation and one anion, usually involves an
“off-on-off”[19-21] or “on-off-on”[22-24] sensing procedure taking place in one
channel, which sometimes could mimic a logic circuit with memory functions. In this
case, the “Write-Read-Erase-Read” logic circuits could only output signals in one
channel with one feedback loop, because one kind of ions could just act one role (pen
or eraser) in these system. In contrast with this, simultaneous multiple analytes
recognition is more interesting, but it is difficult to operate in two channels in the
same solution[16, 25]. On this occasion, both kinds of ions act two roles (pen and
eraser), thus signals can be read in two channels. Consequently, a dual-channel
“Write-Read-Erase-Read” logic circuit with two feedback loops is potential to be
constructed. This kind of logic circuits has possible implication in the development of
more advanced and complex electronic devices. Therefore, our interest is to develop a
reversible multiple-ion detection system with multi-state transition, and further to
design functional set-reset circuits in the area of information storage[25-30].
In order to construct a system for simultaneous recognition of different analytes in
3

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two channels in the same condition, the sensor should contain different recognition
sites or utilize different recognition mechanisms. Salicylidene Schiff bases are
versatile ion sensors in that they form strong complexes with metal cations and
undergo deprotonation and/or addition reactions with basic/nucleophilic anions[31,
3
2]. So it is possible to realize simultaneous recognition of different analytes by using
3
+
their derivatives. Of numerous common cations and anions, Al and F‾ are unusual
because of their strong mutual complexation, a reaction which can therefore be
brought into competition with their separate detection or sensing[33, 34]. Sensors for
3
+
recognition of Al and/or F‾ are numerous[33-40]. Among them, some sensors for
3
+
sequential recognition of Al and F‾ have been studied[36-39]. To the best of our
3
+
knowledge, a chemosensor system for Al
and F‾ with dual-channel
“Write-Read-Erase-Read” function has not been reported.
In our previous study, a salicylimine-based sensor L (Scheme S1) was used as a
3
+
3+
fluorescent sensor for Al , then L-Al ensemble was a subsequent fluorescent sensor
3
+
for PPi[41]. In that case, Al could act a pen and PPi act an eraser. The “off-on-off”
3
+
sensing phenomenon caused by Al and PPi is reversible in fluorescent channel.
3
+
Herein, the reported receptor L has been improved to function as a simultaneous Al
3
+
and F‾ probe in different optical channel. The input of only F‾ or Al produces a
colorimetric or fluorescent output signal in one of the two channels, respectively. The
stoichiometric addition of the counter ions leads to the reduction of the output signal,
due to the formation of AlF , which competes with the binding between the Schiff
3
3
+
base and the ions. In such a functional circuit, both of the Al and F‾ act two
4

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roles——pen and eraser, thus signals can be read in two channels. Consequently, an
interesting reversible and reconfigurable multi-state “Write-Read-Erase-Read”
(W-R-E-R) logic circuit possessing multi-write ability with two feedback loops is
obtained.
2
. Experimental
2
.1. Chemicals and instruments
3
,5-di-tert-butyl-2-hydroxy-benzaldehyde was purchased from Aldrich.
2
-aminophenol was purchased from Sinopharm Chemical Reagent Co.Ltd. Analytical
grade solvents for synthesis and spectra were purchased from commercial suppliers.
All reagents and solvents were used as received without further purification. The
water used in all experiments was deionized water. Electronic absorption spectra were
recorded using a Shimadzu 3100 UV-Vis-NIR spectrophotometer and fluorescence
spectra recorded using a Shimadzu RF-5301 PC spectrofluorimeter. Nuclear magnetic
resonance spectra were recorded on a Bruker Ultra Shield 500 MHz instrument,
chemical shifts being expressed in ppm using TMS as an internal standard. ESI-mass
spectra were measured on Bruker Agilent1290-micrOTOF Q II. FT-IR spectra were
measured on Brucker VERTEX 80V, with samples dispersed in KBr discs. Elemental
analyses were performed using an Elementar vario MICRO cube instrument.
2
.2. Physical measurements
All measurements were performed at room temperature and repeated at least once.
.2.1. Preparation and characterization of reagent solutions
A stock solution of L (1 mM) was prepared in DMSO. For the measurements of
2
5

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fluoride ion selectivity, solutions of different anions (10mM) were prepared for F‾, Cl‾,
Br‾, I‾, AcO‾, H PO ‾, BF ‾, NO ‾ as their tetrabutylammonium (TBA) salts in DMSO.
2
4
4
3
Solutions containing L (50 μM) and each of the different anions (750 μM) were
prepared by appropriate dilution and their absorption spectra were then recorded. For
3
+
the measurements of Al selectivity, solutions of different (10 mM) cations were
prepared from AlCl , BaCl ·2H O, CaCl , CdCl ·2.5H O, CoCl ·6H O, CrCl ·6H O,
3
2
2
2
2
2
2
2
3
2
CuCl ·2H O, PbCl , FeCl ·4H O, FeCl , HgCl , KCl, MnCl ·4H O, NaCl,
2
2
2
2
2
3
2
2
2
NiCl ·6H O, ZnCl and MgCl ·6H O in H O. Solutions containing L (10 μM) and the
2
2
2
2
2
2
different cations (100 μM) were again prepared by appropriate dilution using DMSO
and their fluorescence spectra were recorded for a common excitation wavelength of
3
65 nm.
2
.2.2. Spectrophotometric and spectrofluorimetric titrations
Stock solutions of L (1mM) and TBAF (tetrabutyalammonium fluoride; 10 mM)
3
+
were prepared in DMSO and of Al (10 mM) by dissolving AlCl in H O. Solutions
3
2
containing L (50 μM) and increasing concentrations of F‾ (0-900 μM) were prepared
by appropriate dilutions and their absorption spectra (300 – 650 nm) recorded.
3
+
Solutions containing L (10 μM) and increasing concentrations of Al (0-100 μM)
were prepared by appropriate dilutions using DMSO and their emission spectra (450 –
6
50 nm) recorded for an excitation wavelength of 365 nm.
.2.3. Job plot measurements
2
For F‾, a series of solution containing L and F‾ were prepared such that the total
concentration of F‾ and L was 100 μM. The mole fraction of F‾ was varied from 0.1
6

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to 1.0. The absorbance at 448 nm was plotted against the molar fraction of F‾. For
3
+
3+
Al , a series of solution containing L and Al were prepared such that the total
3
+
3+
concentration of Al and L was 20 μM. The mole fraction of Al was varied from
0
.1 to 1.0. The fluorescence intensity at 510 nm was plotted against the molar fraction
3
+
of Al .
.2.4. Determination of fluorescence quantum yield for Al binding:
The quantum yield was measured at room temperature referenced to quinine
3
+
2
sulfate in sulfuric acid aqueous solution (Ф = 0.546) and calculated according to the
fr
following equation:


ArLr
AsLs
2
1
1
10
10
Ns Ds
 fs   


fr
2
Nr Dr
where Ф is the radiative quantum yield of the sample; Ф is the radiative
fs
fr
quantum yield of the standard; A and A are the absorbance of the sample and
s
r
standard at the excitation wavelength, respectively; D and D are the integrated areas
s
r
of the emission for sample and standard, respectively; L and L are the lengths of the
s
r
absorption cells for the sample and standard test; and N and N are the indices of
s
r
refraction of the sample and standard solutions (pure solvents were assumed),
respectively.
3
+
2
.2.5. Determination of detection limit for F‾ and Al :
3
+
The limits of detection (DL) of L for F‾ and Al were determined from the
following equation:
DL = 3 σ / K
where σ is the standard deviation of the blank solution; K is the slope of the
7

ACCEPTED MANUSCRIPT
calibration curve. The detection limit was calculated based on the absorption titration
3
+
for F‾ and fluorescence titration for Al .
.2.6. Determination of the association constants for F‾ and Al with L:
Assuming in both cases a 1:1 equilibrium (confirmed by the Job plot
3
+
2
measurements), both the spectrophotometric and spectrofluorimetric data were
analysed to give K values using the Benesi-Hildebrand treatment[42]. Thus, for F‾
a
binding the K value was obtained by fitting the equation:
a
1
/(A-A ) = 1/{K(A –A ) [F‾]} + 1/(A -A )
min max min max min
where Amax, A , and A are absorbance of L in the presence of F‾ at saturation,
min
free L, and any intermediate F‾ concentration. The association constant (K) could be
determined from the slope of the straight line of the plot of 1/(A-A ) against 1/[F‾].
min
2
.3. The synthesis of L
Sensor L (2,4-di-tert-butyl-6-((2-hydro-xyphenyl-imino)-methyl)phenol) was
synthesized and characterized in our previous work[41].
3
. Results and discussion
3
.1 Colorimetric channel for fluoride sensing
The selectivity of L towards the anions F‾, Cl‾, Br‾, I‾, AcO‾, H PO ‾, HSO ‾,
2
4
4
ClO ‾, NO ‾ and BF ‾ was investigated in DMSO solution. Of these anions, only
4
3
4
fluoride caused a noticeable color change from colorless to orangish immediately (Fig.
). The color change was visible to the naked eye (inset in Fig. 1). No obvious color
1
changes were observed in the presence of other anions, presumably due to their
weaker interactions with the receptor. L alone shows an absorption maximum at 354
8

ACCEPTED MANUSCRIPT
nm which decreases in intensity on addition offluoride, while absorption near 448,
5
10 and 560 nm is markedly increased.
The spectrophotometric titration of L with F‾ in Fig. 2 showed an isosbestic point
at 391 nm, indicating the formation of single complex species between L and
-6
fluoride[43]. The detection limit was calculated to be 2.45×10 M with a linearity
range from 0 to 50 μM for the response to fluoride (Fig. S1). The value of the binding
3
-1
constant found by Benesi-Hildebrand (B-H) analysis[42] was 4.44×10 M with a
2
satisfactory correlation coefficient value (R = 0.9990) (Fig. S2). The Job plot (Fig. S3)
showed a maximum at the mole fraction of 0.5, confirming the apparent 1:1 binding
stoichiometry.
1
To further elucidate the interaction between L and F‾, H NMR spectra of L were
measured in the presence of different amounts of F‾ in DMSO-d solution (Fig. 3).
6
Upon the addition of fluoride, the signals at 14.49 ppm and 9.76 ppm (-OH and -OH )
a
c
disappeared. This result may be attributed to possible double hydrogen bonding of the
Y-shaped ion causing stronger binding[43]. The signal at 8.97 ppm corresponding to
the CH=N proton was gradually shifted downfield. The protons on the phenyl ring
were shifted upfield gradually, indicating the increase of the electron density on the
phenyl ring. A new 1:2:1 triplet signal at 16.09 ppm appeared after the addition of 3
equivalents of fluoride, which was ascribed to the FHF‾ dimer (Fig. 3g)[44]. The
existence of this new species confirmed the deprotonation of the -OH group[44, 45].
These observations suggest that the interaction of F‾ with L is mainly due to the
formation of a hydrogen bonded anion-receptor complex followed by the
9

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deprotonation of L. The deprotonation mechanism of sensing F‾ with L was further
proved by titration of OH‾, the most basic anion, as shown in Fig. S4. The changes
were almost the same as that using F‾, indicating that deprotonation really happened
when F‾ existed in the solution of L.
3
.2 Fluorescence channel for aluminium ion sensing
has an intramolecular hydrogen bond between the phenolic O-H and the
nitrogen of the imine that undergoes excited state intramolecular proton transfer
ESIPT)[46, 47]. More specifically, the ESIPT process commonly involves the
transfer of a proton donor (-OH, -NH ) to an adjacent proton acceptor (-C=O,
L
(
2
-
N=) through a six-membered ring of hydrogen-bonding configuration.
3
+
Recently, many studies have reported o-hydroxy Schiff bases as Al selective
probe by describing inhibition of ESIPT as the key sensing mechanism[48-51].
In DMSO solution, the fluorescence emission intensity of
90 nm, but it was too weak and could not be observed by naked eyes. It was
probably due to rapid C=N isomerization[46, 52], and also due to excited-state
L was recorded at
4
3
+
intramolecular proton transfer (ESIPT). The addition of Al ion resulted in
fuorescence at 510 nm, the system thus exhibiting an “off-on” emission. In the
3
+
presence of Al , the proton of the donor will be removed, as a result, the
excited-state intramolecular proton transfer process is inhibited and a
significant emission enhancement can be observed. The presence of other
2
+
2+
2+
2+
3+
2+
2+
2+
3+
2+
+
2+
cations (Ba , Ca , Cd , Co , Cr , Cu , Pb , Fe , Fe , Hg , K , Mn ,
+
2+
2+
2+
Na , Ni , Zn and Mg ) led to negligible fluorescence changes, as shown in
1
0

ACCEPTED MANUSCRIPT
3
+
Fig. 4. The solution of
L containing Al showed bright green fluorescence
under 365 nm ultraviolet lamp irradiation (inset in Fig. 4). The selective
3
+
fluorescence enhancement by Al can be ascribed to both inhibition of C=N
isomerization and chelation enhanced fluorescence (CHEF)[20, 35, 53].
3
+
Coordination of Al to oxygen atoms and nitrogen atom inhibited the ESIPT
process and increased the rigidity of the molecule, and thus brought a
significant enhancement of the fluorescence intensity.
3
+
The sensitivity of L for Al was studied by fluorescence titration, as shown in Fig.
3
+
5
. The fluorescence was detectable down to very low concentrations of Al , the
-8
detection limit being 2.56×10 M with a linearity range from 0 to 10 μM (Fig. S5).
3
-1
2
The association constant was calculated to be 7.45×10 M (R = 0.9974) from the
fluorescence titration data using the Benesi-Hildebrand equation (Fig. S6). The
intensity of the fluorescence had a 146-fold enhancement and the fluorescence
quantum yield (Ф, quinine sulfate as standard) was 0.69. Again, the Job plot (Fig. S7)
for the titration showed a maximum at a mole fraction of 0.5, indicating a 1:1 binding
stoichiometry, consistent with the fit applied to the titration results.
A competition experiment (Fig. S8) showed that most of the other cations tested
3
+
2+
did not interfere with the detection of Al by L. Only Cu led to complete
fluorescence quenching. L still had sufficient “turn-on” ratios for the detection of
3
+
2+
3+
2+
Al in the presence of Fe , Fe and Hg , in which cases the intensity increased
about 38-fold, 9-fold and 71-fold, respectively.
3
+
1
To gain a further understanding of interaction between L and Al , H NMR
11

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3
+
spectra of L were measured in the absence and presence of Al in DMSO-d solution
6
3+
(
Fig. 6). When 3 equivalents of Al were added to L, the -OH and -OH protons
a c
disappeared completely and many new peaks appeared. The proton H on imine
b’
3
+
group for L-Al appeared at 8.93 ppm, and aromatic protons also could be found at
3
+
other position remarkably upon Al complexation (Fig. 6B). This result supported the
3
+
formation of L-Al complex under the participation of both O and N atoms.
3
.3 Reversible sensing behavior
According to the investigation mentioned above, L has a high selectivity for the
3
+
detection of F‾ and Al in colorimetric/fluorescent channel over the tested anions and
cations, respectively. Inspired by the competition between the formation of AlF and
3
3
+
the complexes of Al or F‾ with the receptor L, we further investigated the dynamic
3
+
3+
switch behavior of L with F‾ and Al . As F‾ can combine with Al to form AlF
3
3
+
complex in a ratio of 3 to 1, 6 equivalents of F‾ or 2 equivalents of Al were added
each time.
The reversible sensing behavior of L for F‾ was investigated using the
3+
colorimetric channel over three cycles by the addition of F‾ followed by that of Al .
As shown in Fig. 7, after the first addition of F‾, the receptor L combined with it and
the color of the solution changed from colorless to orangish, the absorption band
3
+
appearing having a maximum at 510 nm. The subsequent addition of Al caused the
3
+
color to fade and the absorption band to disappear. Because Al competitively
combined with F‾ in the solution, free L was released. When more F‾ was added to the
solution, the color reappeared and the reversible inter-conversion of L-FL-L could be
1
2

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repeated several times with negligible differences in the absorbance changes. This
result indicated that L could be developed as a reversible colorimetric off-on-off
3
+
sensor by alternately adding F‾ and Al (Scheme 1, right part).
3
+
Similarly, the reversible sensing behavior of L for Al was investigated using the
3
+
fluorescent channel over three cycles of the addition of Al followed by F‾. As shown
3
+
3+
in Fig. 8, after the addition of Al , coordination of L to Al produced a green
fluorescence with a peak at 510 nm. Then, addition of F‾ resulted in fluorescence
3
+
quenching. This result was due to the stronger combination ability of F‾ with Al ,
3
+
which led to the dissociation of L-Al complex. The fluorescence was regenerated
3
+
when more Al was added to the solution. The reversible inter-conversion of
L-AlL-L was repeated several times with negligible fluorescence intensity changes.
This result suggests that L could be developed as a reversible fluorescent off-on-off
3
+
sensor by alternately adding Al and F‾ (Scheme 1, left part).
1
To illustrate the optical reversible behavior, H NMR spectra of L, L+F‾ and
3
+
L+F‾+ Al mixtures were measured (Fig. 9). When 3 equivalents of F‾ were added to
L, the signals belonged to phenolic hydroxyl protons disappeared, the signal for
proton on the CH=N was shifted downfield, and the protons on the phenyl ring were
shifted upfield dramatically. These changes were attributed to the deprotonation of the
3
+
-
OH groups. After adding 1 equivalent of Al to the above mentioned L-F‾ complex,
the chemical shift signals for protons on the CH=N and phenyl ring of L were shifted
3
+
back. This observation indicated that a competition reaction occurred between Al
and F‾ with L due to the formation of AlF complex. These results established that L
3
1
3

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could be used repeatedly as a reversible sensor for sensing purposes.
3
.4“Write-Read-Erase-Read” function
It is important to note that L-F‾ was non-fluorescent and there was no absorbance
3+
at 510 nm in the solution of L-Al (Scheme 1, Fig. S9-S10). That is to say, the
absorbance at 510 nm appeared only in the presence of L-F‾, while the emission at
3
+
5
10 nm appeared only in the presence of L-Al . Thus, the addition of F‾ to the
solution of L only caused a color change from colorless to orangish, while no
3
+
fluorescence changes could be observed. Similarly, the addition of Al to the solution
of L only caused a green fluorescence enhancement, while no obvious color changes
3
+
were observed. The addition of Al to the solution of L-F‾ and the addition of F‾ to
3+
the solution of L- Al resulted in the dissociation of the corresponding complex and
release of free L. These results indicated that L could be developed as a reversible
3
+
off-on-off sensor by alternately adding F‾ and Al in the colorimetric channel, while
3
+
it could also be developed as a reversible off-on-off sensor by alternately adding Al
and F‾ in the fluorescent channel.
The most interesting aspect of this system is that these two channels can both be
used to follow the same reactions. As shown in Fig. 10, the addition of F‾ caused
3
+
color change from colorless to orangish, the color disappeared after adding of Al
due to the formation of the AlF complex and releasing the free L, which is colorless
3
3
+
and non-fluorescent. At this time, if Al were added, the free L was able to bind with
3
+
Al and thereafter green fluorescence appeared. Finally, addition of F‾ resulted in
3
+
fluorescence quenching. By controlling the addition order of F‾ and Al , the
1
4

ACCEPTED MANUSCRIPT
reversible signals can not only be implemented in a single colorimetric or fluorescent
channel (Fig. 7 and Fig. 8), but also can be interpenetrated between the two channels
(Fig. 10).
This reversible sensing behavior could mimic a logic circuit (consists of two
3
+
INHIBIT gates), depending upon the different chemical inputs (Al and F‾) and dual
channel outputs (emission at 510 nm and absorbance at 510 nm) with ‘YES’ i.e. 1 or
‘NO’ i.e. 0. The truth table and the logic circuit are shown in Fig. 11. As discussed
3
+
above, the emission at 510 nm (OUT1) appeared only under the addition of Al (IN1),
while the absorbance at 510 nm (OUT2) appeared only under the action of F‾ (IN2).
Only when IN1 = 1, IN2 = 0 does the output signal OUT1 = 1, and only when IN1 = 0,
IN2 = 1 does the output signal OUT2 = 1. Otherwise, the values for the other actions
are all 0.
As a result, the reversible and reconfigurable sequences can be visualized as
3
+
follows (Fig. 12). When Al was added as the set input (IN1 = 1, in the left feedback
loop), the fluorescence turned on, and this readout stored the information as “written”.
Then the stored encoded information can be “erased” by adding F‾ as reset input (IN2
3
+
=
1). In this case, Al acts as a pen and F‾ acts as an eraser in fluorescent channel. In
contrast, if more F‾ were added as the other set input (IN2 = 1, in the right feedback
loop), the color appeared and this readout stored the information as “written”. Then
3
+
the stored encoded information can be “erased” by adding Al as reset input (IN1 =
3
+
3+
1
). F‾ acts as a pen and Al acts as an eraser in colorimetric channel. Both of Al and
F‾ have double roles that can write as well as erase information, signals can be
1
5

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recorded in two channels and reversible signal conversion can be realized between
three states in two feedback loops (OUT1 = 1, OUT2 = 0 as the “Fluorescent Channel
On” state, OUT1 = 0, OUT2 = 1 as the “Colormetric Channel On” state and OUT1 =
3
+
0
, OUT2 = 0 as the “OFF” state). Al /F‾ are set input in one feedback but reset input
in the other feedback loop. L represents an interesting dual channel data storage
feature with “W-R-E-R” function possessing multi-write ability and demonstrates a
potential multiple-state memory circuit.
4
. Conclusion
In summary, we have developed a simple dual channel molecular sensor L for
fluoride and aluminum ions via independent mechanisms. This sensor showed a
highly selective colorimetric response to fluoride based on a deprotonation process.
3
+
On the other hand, this sensor can enable fluorescent detection of Al selectively due
to the inhibition of C=N isomerization, cation-induced inhibition of ESIPT and CHEF.
3
+
L behaves as a reversible switch by sequential input of F‾ and Al , and constitutes a
very favorable two-channel optical switch. This reversible switch behavior realizes
transformation between multiple states and can be considered as
a
“Write-Read-Erase-Read” memory function for information storage. The novelty of
this system provides inspiration for the research community to look for similar
designs towards multi-channel ion recognition and advanced logic gates.
Acknowledgements
This work was supported by the National Natural Science Foundation of China
(21374036 and 51673082).
1
6

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Appendix A. Supplementary Data
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.saa.XXXX.XX.XXX.
1
7

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Biographies
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Chunshuang Liang received her BSc degree in chemistry from Jilin University in
2
012. Currently she is a graduate student of the College of Chemistry in Jilin
University.
Shimei Jiang is a professor of Chemistry at Jilin University. She received her PhD
degree from Jilin University in 1998. Her main research interests are stimuli-
responsive supramolecular systems and nano-materials.
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Figure captions:
Fig. 1. Absorption spectra of L (50 μM) before and after addition of various anions
750 μM) of F‾, Cl‾, Br‾, I‾, AcO‾, H PO ‾, HSO ‾, ClO ‾, NO ‾ and BF ‾ in DMSO.
(
2
4
4
4
3
4
Inset: Color changes observed upon the addition of F‾ to the solution of L.
Fig. 2. Absorption spectra of L (50 μM) upon addition of increasing amounts of F‾
(0-900 μM) in DMSO. Inset: absorbance at 448 nm versus the concentration of F‾
added.
1
Fig. 3. H NMR spectra of L (2.5 mM, DMSO-d ) with the addition of TBAF
6
(
DMSO-d solution). (a) L only, (b) L+F‾ (0.5 mM), (c) L+F‾ (1.25 mM), (d) L+F‾
6
(2.5 mM), (e) L+F‾ (3.75 mM), (f) L+F‾ (5.0 mM), (g) L+F‾ (7.5 mM).
Fig. 4. Fluorescence spectra of L (10 μM) before and after addition of various metal
3+
2+
2+
2+
2+
3+
2+
2+
2+
3+
2+
+
ions (100 μM) of Al , Ba , Ca , Cd , Co , Cr , Cu , Pb , Fe , Fe , Hg , K ,
2
+
+
2+
2+
2+
Mn , Na , Ni , Zn and Mg in DMSO, λ = 420 nm. Inset: Fluorescence changes
ex
3
+
observed upon the addition of Al to the solution of L.
Fig. 5. Fluorescence spectra of L (10 μM, λ = 420 nm ) upon addition of increasing
ex
3
+
amounts of Al ion (0-100 μM) in DMSO. Inset: intensity at 510 nm versus the
3
+
concentration of Al added.
1
3+
Fig. 6. H NMR spectra of L (2.5 mM, DMSO-d ) with the addition of Al (D O
6
2
3
+
solution). (a) L only, (b) L+ Al (7.5 mM).
Fig. 7. (a) Visual color changes and (b) spectral changes of L (50 μM) in colorimetric
3
+
channel after adding F‾ (300 μM) and Al (100 μM) alternately.
Fig. 8. (a) Visual fluorescent changes and (b) spectral changes of L (50 μM) in
2
7

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3
+
fluorescent channel after adding F‾ (300 μM) and Al (100 μM) alternately. λ = 420
ex
nm.
Scheme 1. Graphic of the proposed mechanism of the dynamic switching of F‾ and
3
+
Al and corresponding photos in the daylight (left) and under UV lamp (right)
1
3+
Fig. 9. H NMR spectra of L (2.5 mM), L+F‾ (7.5 mM), and L+F‾+ Al (2.5 mM).
3
+
Fig. 10. (a) Dual channel changes after addition of F‾ and Al sequentially into the
solution of L. (b) Reversible cyclic behavior of L upon the sequential addition of F‾
3
+
3+
3+
and Al ; 1 = L; 2 = [1 + F‾]; 3 = [2 + Al ]; 4 = [3 + Al ]; 5 = [4 + F‾], F‾ is 3
3
+
equivalents to Al .
Fig. 11. (a) Truth Table for logic circuit, where 0 = Off and 1 = On signals. (b) Logic
circuit with two inputs and two outputs.
Fig. 12. Schematic representation of the reversible logic operations for a memory
element possessing "write-read-erase-read" functions.
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Fig. 1. Absorption spectra of L (50 μM) before and after addition of various anions
(
750 μM) of F‾, Cl‾, Br‾, I‾, AcO‾, H PO ‾, HSO ‾, ClO ‾, NO ‾ and BF ‾ in DMSO.
2 4 4 4 3 4
Inset: Color change observed upon the addition of F‾ to the solution of L.
2
9