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Single sensor for multiple analytes in different optical channel: Applying for multi-ion response modulation
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 183 (2017) 267–274
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Single sensor for multiple analytes in different optical channel: Applying for multi-ion response modulation Chunshuang Liang, Shimei Jiang ⁎ State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012, PR China
a r t i c l e
i n f o
Article history: Received 2 February 2017 Received in revised form 12 April 2017 Accepted 16 April 2017 Available online 18 April 2017 Keywords: Multiple analytes Fluoride Aluminum ion Dual-channel Reversible Multi-state logic circuit
a b s t r a c t 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_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. © 2017 Elsevier B.V. All rights reserved.
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 “WriteRead-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
⁎ Corresponding author. E-mail address: [email protected] (S. Jiang).
http://dx.doi.org/10.1016/j.saa.2017.04.026 1386-1425/© 2017 Elsevier B.V. All rights reserved.
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 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 [31,32]. So it is possible to realize simultaneous recognition of different analytes by using their derivatives. Of numerous common cations and anions, Al3+ 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 recognition of Al3+ and/or F− are numerous [33–40]. Among them, some sensors for sequential recognition of Al3+ and F− have been studied [36–39]. To the best of our knowledge, a chemosensor system for Al3+ 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 fluorescent sensor for Al3+, then L-Al3+ ensemble was a subsequent fluorescent sensor for PPi [41]. In that case, Al3+ could act a pen and PPi act an eraser. The “off-on-off” sensing phenomenon caused by Al3+ and PPi is reversible in fluorescent channel. Herein, the reported receptor L has been improved to function as a simultaneous Al3+ and F− probe in different optical channel. The input of only F− or Al3+ 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 AlF3, which competes with the binding between the Schiff base and
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the ions. In such a functional circuit, both of the Al3+ and F− act two 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 multiwrite 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 80 V, 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. 2.2.1. Preparation and Characterization of Reagent Solutions A stock solution of L (1 mM) was prepared in DMSO. For the measurements of fluoride ion selectivity, solutions of different anions − − (10 mM) were prepared for F−, Cl−, Br−, I−, AcO−, H2PO− 4 , BF4 , NO3 as their tetrabutylammonium (TBA) salts in DMSO. 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 the measurements of Al3+ selectivity, solutions of different (10 mM) cations were prepared from AlCl3, BaCl2·2H2O, CaCl2, CdCl2·2.5H2O, CoCl2·6H2O, CrCl3·6H2O, CuCl2·2H2O, PbCl2, FeCl2·4H2O, FeCl3, HgCl2, KCl, MnCl2·4H2O, NaCl, NiCl2·6H2O, ZnCl2 and MgCl2·6H2O in H2O. Solutions containing L (10 μM) and the different cations (100 μM) were again prepared by appropriate dilution using
Fig. 1. Absorption spectra of L (50 μM) before and after addition of various anions (750 − − − − μM) of F−, Cl−, Br−, I−, AcO−, H2PO− 4 , HSO4 , ClO4 , NO3 and BF4 in DMSO. Inset: Color change observed upon the addition of F− to the solution of L.
DMSO and their fluorescence spectra were recorded for a common excitation wavelength of 365 nm. 2.2.2. Spectrophotometric and Spectrofluorimetric Titrations Stock solutions of L (1 mM) and TBAF (tetrabutyalammonium fluoride; 10 mM) were prepared in DMSO and of Al3+ (10 mM) by dissolving AlCl3 in H2O. Solutions 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. Solutions containing L (10 μM) and increasing concentrations of Al3+ (0–100 μM) were prepared by appropriate dilutions using DMSO and their emission spectra (450–650 nm) recorded for an excitation wavelength of 365 nm. 2.2.3. Job Plot Measurements 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 to 1.0. The absorbance at 448 nm was plotted against the molar fraction of F−. For Al3+, a series of solution containing L and Al3+ were prepared such that the total concentration of Al3+ and L was 20 μM. The mole fraction of Al3+ was varied from 0.1 to 1.0. The fluorescence intensity at 510 nm was plotted against the molar fraction of Al3+. 2.2.4. Determination of Fluorescence Quantum Yield for Al3+ Binding The quantum yield was measured at room temperature referenced to quinine sulfate in sulfuric acid aqueous solution (Фfr = 0.546) and calculated according to the following equation: Φfs ¼ Φfr
1−10−ArLr 1−10
−AsLs
N2s N2r
Ds Dr
where Фfs is the radiative quantum yield of the sample; Фfr is the radiative quantum yield of the standard; As and Ar are the absorbance of the sample and standard at the excitation wavelength, respectively; Ds and Dr are the integrated areas of the emission for sample and standard, respectively; Ls and Lr are the lengths of the absorption cells for the sample and standard test; and Ns and Nr are the indices of refraction of the sample and standard solutions (pure solvents were assumed), respectively. 2.2.5. Determination of Detection Limit for F− and Al3+ The limits of detection (DL) of L for F− and Al3+ were determined from the following equation: DL ¼ 3 σ=K
Fig. 2. Absorption spectra of L (50 μM) upon addition of increasing amounts of F− (0–900 μM) in DMSO. The arrows indicate the change in the absorbance intensity with the increased F− ions. Inset: absorbance at 448 nm versus the concentration of F− added.
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Fig. 3. 1H NMR spectra of L (2.5 mM, DMSO-d6) with the addition of TBAF (DMSO-d6 solution). (a) L only, (b) L + F− (0.5 mM), (c) L + F− (1.25 mM), (d) L + F− (2.5 mM), (e) L + F− (3.75 mM), (f) L + F− (5.0 mM), (g) L + F− (7.5 mM).
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Fig. 5. Fluorescence spectra of L (10 μM, λex = 420 nm) upon addition of increasing amounts of Al3+ ion (0–100 μM) in DMSO. The arrow indicates the change in the emission intensity with the increased Al3+ ions. Inset: intensity at 510 nm versus the concentration of Al3+ added.
where σ is the standard deviation of the blank solution; K is the slope of the calibration curve. The detection limit was calculated based on the absorption titration for F− and fluorescence titration for Al3+.
3. Results and Discussion
2.2.6. Determination of the Association Constants for F− and Al3+ with L Assuming in both cases a 1:1 equilibrium (confirmed by the Job plot measurements), both the spectrophotometric and spectrofluorimetric data were analysed to give Ka values using the Benesi-Hildebrand treatment [42]. Thus, for F− binding the Ka value was obtained by fitting the equation:
The selectivity of L towards the anions F−, Cl−, Br−, I−, AcO−, H2PO− 4 , − − − HSO− 4 , ClO4 , NO3 and BF4 was investigated in DMSO solution. Of these anions, only fluoride caused a noticeable color change from colorless to orangish immediately (Fig. 1). The color change was visible to the naked eye (inset in Fig. 1). No obvious color 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 nm which decreases in intensity on addition offluoride, while absorption near 448, 510 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 fluoride [43]. The detection limit was calculated to be 2.45 × 10−6 M with a linearity range from 0 to 50 μM for the response to fluoride (Fig. S1). The value of the binding constant found by Benesi-Hildebrand (B\\H) analysis [42] was 4.44 × 103 M−1 with a satisfactory correlation coefficient value (R2 = 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. To further elucidate the interaction between L and F−, 1H NMR spectra of L were measured in the presence of different amounts of F− in DMSO-d6 solution (Fig. 3). Upon the addition of fluoride, the signals at 14.49 ppm and 9.76 ppm (\\OHa and\\OHc) 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
1=ðA−Amin Þ ¼ 1=fKðAmax −Amin Þ ½ F− g þ 1=ðAmax −Amin Þ where Amax, Amin, and A are absorbance of L in the presence of F− at saturation, 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−Amin) against 1/[F−]. 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].
Fig. 4. Fluorescence spectra of L (10 μM) before and after addition of various metal ions (100 μM) of Al3+, Ba2+, Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Pb2+, Fe2+, Fe3+, Hg2+, K+, Mn2+, Na+, Ni2+, Zn2+ and Mg2+ in DMSO, λex = 420 nm. Inset: Fluorescence changes observed upon the addition of Al3+ to the solution of L.
3.1. Colorimetric Channel for Fluoride Sensing
Fig. 6. 1H NMR spectra of L (2.5 mM, DMSO-d6) with the addition of Al3+ (D2O solution). (A) L only, (B) L+ Al3+ (7.5 mM).
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Fig. 7. (a) Visual color changes and (b) spectral changes of L (50 μM) in colorimetric channel after adding F− (300 μM) and Al3+ (100 μM) alternately.
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 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 Aluminum Ion Sensing L 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 2 ) to an adjacent proton acceptor (\\C_O, \\N_) through a six-membered ring of hydrogen-bonding configuration. Recently, many studies have reported o-hydroxy Schiff bases as Al 3+ selective probe by describing inhibition of ESIPT as the key sensing mechanism [48–51]. In DMSO solution, the fluorescence emission intensity of L was recorded at 490 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 excitedstate intramolecular proton transfer (ESIPT). The addition of Al 3+ ion resulted in fuorescence at 510 nm, the system thus exhibiting an “off-on” emission. In the presence of Al 3+ , 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 cations (Ba2+, Ca 2+ , Cd 2+ , Co 2+, Cr3+ , Cu2+ , Pb 2+ , Fe 2+, Fe3+ , Hg 2+, K + , Mn2+ ,
Na+, Ni2+, Zn2+ and Mg2+) led to negligible fluorescence changes, as shown in Fig. 4. The solution of L containing Al3+ showed bright green fluorescence under 365 nm ultraviolet lamp irradiation (inset in Fig. 4). The selective fluorescence enhancement by Al3+ can be ascribed to both inhibition of C_N isomerization and chelation enhanced fluorescence (CHEF) [20,35,53]. Coordination of Al3+ 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. The sensitivity of L for Al3+ was studied by fluorescence titration, as shown in Fig. 5. The fluorescence was detectable down to very low concentrations of Al3+, the detection limit being 2.56 × 10−8 M with a linearity range from 0 to 10 μM (Fig. S5). The association constant was calculated to be 7.45 × 103 M−1 (R2 = 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 did not interfere with the detection of Al3+ by L. Only Cu2+ led to complete fluorescence quenching. L still had sufficient “turn-on” ratios for the detection of Al3+ in the presence of Fe2+, Fe3+ and Hg2+, in which cases the intensity increased about 38-fold, 9-fold and 71-fold, respectively. To gain a further understanding of interaction between L and Al3+, 1 H NMR spectra of L were measured in the absence and presence of Al3+ in DMSO-d6 solution (Fig. 6). When 3 equivalents of Al3+ were added to L, the \\OHa and \\OHc protons disappeared completely and many new peaks appeared. The proton Hb’ on imine group for L-Al3+ appeared at 8.93 ppm, and aromatic protons also could be found at other position remarkably upon Al3+ complexation (Fig. 6B). This result supported the formation of L-Al3+ complex under the participation of both O and N atoms.
Scheme 1. Graphic of the proposed mechanism of the dynamic switching of F− and Al3+ and corresponding photos in the daylight (left) and under UV lamp (right).
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Fig. 8. (a) Visual fluorescent changes and (b) spectral changes of L (50 μM) in fluorescent channel after adding F− (300 μM) and Al3+ (100 μM) alternately. λex = 420 nm.
3.3. Reversible Sensing Behavior
3.4. “Write-Read-Erase-Read” Function
According to the investigation mentioned above, L has a high selectivity for the detection of F− and Al3+ in colorimetric/fluorescent channel over the tested anions and cations, respectively. Inspired by the competition between the formation of AlF3 and the complexes of Al3+ or F− with the receptor L, we further investigated the dynamic switch behavior of L with F− and Al3+. As F− can combine with Al3+ to form AlF3 complex in a ratio of 3 to 1, 6 equivalents of F− or 2 equivalents of Al3+ were added each time. The reversible sensing behavior of L for F− was investigated using the colorimetric channel over three cycles by the addition of F− followed by that of Al3+. 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 appearing having a maximum at 510 nm. The subsequent addition of Al3+ caused the color to fade and the absorption band to disappear. Because Al3+ 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 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 sensor by alternately adding F− and Al3+ (Scheme 1, right part). Similarly, the reversible sensing behavior of L for Al3+ was investigated using the fluorescent channel over three cycles of the addition of Al3+ followed by F−. As shown in Fig. 8, after the addition of Al 3+ , coordination of L to Al 3+ produced a green fluorescence with a peak at 510 nm. Then, addition of F− resulted in fluorescence quenching. This result was due to the stronger combination ability of F− with Al 3+, which led to the dissociation of L-Al 3+ complex. The fluorescence was regenerated when more Al 3+ 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 sensor by alternately adding Al3+ and F− (Scheme 1, left part). To illustrate the optical reversible behavior, 1H NMR spectra of L, L + F− and L + F− + Al3+ 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\\OH groups. After adding 1 equivalent of Al3+ to the above mentioned L-F− complex, the chemical shift signals for protons on the CH_N and phenyl ring of L were shifted back. This observation indicated that a competition reaction occurred between Al3+ and F− with L due to the formation of AlF3 complex. These results established that L could be used repeatedly as a reversible sensor for sensing purposes.
It is important to note that L-F− was non-fluorescent and there was no absorbance at 510 nm in the solution of L-Al3+ (Scheme 1, Figs. S9–S10). That is to say, the absorbance at 510 nm appeared only in the presence of L-F−, while the emission at 510 nm appeared only in the presence of L-Al3+. Thus, the addition of F− to the solution of L only caused a color change from colorless to orangish, while no fluorescence changes could be observed. Similarly, the addition of Al3+ to the solution of L only caused a green fluorescence enhancement, while no obvious color changes were observed. The addition of Al3+ to the solution of L-F− and the addition of F− to the solution of L- Al3+ resulted in the dissociation of the corresponding complex and release of free L. These results indicated that L could be developed as a reversible off-on-off sensor by alternately adding F− and Al3+ in the colorimetric channel, while it could also be developed as a reversible off-on-off sensor by alternately adding Al3+ 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 color change from colorless to orangish, the color disappeared after adding of Al3+ due to the formation of the AlF3 complex and releasing the free L, which is colorless and non-fluorescent. At this time, if Al3+ were added, the free L was able to bind with Al3+ and thereafter green fluorescence appeared. Finally, addition of F− resulted in fluorescence quenching. By controlling the addition order of F− and Al3+, the reversible signals can not only be implemented in a single colorimetric or fluorescent channel (Figs. 7 and 8), but also can be interpenetrated between the two channels (Fig. 10). This reversible sensing behavior could mimic a logic circuit (consists of two INHIBIT gates), depending upon the different chemical inputs
Fig. 9. 1H NMR spectra of L (2.5 mM), L + F− (7.5 mM), and L + F− + Al3+ (2.5 mM).
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Fig. 10. (a) Dual channel changes after addition of F− and Al3+ sequentially into the solution of L. (b) Reversible cyclic behavior of L upon the sequential addition of F− and Al3+; 1 = L; 2 = [1 + F−]; 3 = [2 + Al3+]; 4 = [3 + Al3+]; 5 = [4 + F−], F− is 3 equivalents to Al3+.
Fig. 11. (a) Truth Table for logic circuit, where 0 = Off and 1 = On signals. (b) Logic circuit with two inputs and two outputs.
(Al3+ 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 above, the emission at 510 nm (OUT1) appeared only under the addition of Al3+ (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 follows (Fig. 12). When Al3+ 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 = 1). In this case, Al3+ 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 the stored encoded information can be “erased” by adding Al3+ as reset input (IN1 = 1). F− acts as a pen and Al3+ acts as an eraser in colorimetric channel. Both of Al3+ and F− have double roles that can write as well as erase information, signals can be 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 = 0, OUT2 = 0 as the “OFF” state). Al3+/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
Fig. 12. Schematic representation of the reversible logic operations for a memory element possessing “write-read-erase-read” functions.
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. On the other hand, this sensor can enable fluorescent detection of Al3+ selectively due to the inhibition of C_N isomerization, cation-induced inhibition of ESIPT and CHEF. L behaves as a reversible switch by sequential input of F− and Al3+, 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 multichannel ion recognition and advanced logic gates.
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Acknowledgements This work was supported by the National Natural Science Foundation of China (21374036 and 51673082). Appendix A. Supplementary Data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.saa.2017.04.026. References [1] X. Zhou, X. Wu, J. Yoon, A dual FRET based fluorescent probe as a multiple logic system, Chem. Commun. 51 (2015) 111–113. [2] V. García, A. Fernández-Lodeiro, R. Lamelas, A. Macías, R. Bastida, E. Bértolo, C. Núñez, Novel chromogenic macrocyclic molecular probes with logic gate function using anion/cation inputs, Dyes Pigments 110 (2014) 143–151. [3] M. Orłowska, A.M. Kłonkowski, J. Jezierska, J. Ryl, Luminescence recognition material as an INHIBIT logic gate in presence of Pb2+ and Cu2+ ions in aqueous solutions, Sensors Actuators B Chem. 186 (2013) 396–406. [4] S. Mardanya, S. Karmakar, S. Das, S. Baitalik, Anion and cation triggered modulation of optical properties of a pyridyl-imidazole receptor rigidly linked to pyrene and construction of INHIBIT, OR and XOR molecular logic gates: a combined experimental and DFT/TD-DFT investigation, Sensors Actuators B Chem. 206 (2015) 701–713. [5] K.-C. Chang, I.-H. Su, Y.-Y. Wang, W.-S. Chung, A bifunctional chromogenic calix[4]arene chemosensor for both cations and anions: a potential Ca2+ and F− switched INHIBIT logic gate with a YES logic function, Eur. J. Org. Chem. (2010) 4700–4704. [6] V. Luxami, A.S. Gupta, K. Paul, Dansyl–antipyrine dyad as a fluorescent sensor for Cu2+ and F−: sequential XNOR logic operation, New J. Chem. 38 (2014) 2841–2846. [7] N. Madhuprasad, J.R. Swathi, U.K. Manjunatha, A.N. Das, D.R. Shetty, Trivedi, dual colorimetric receptor with logic gate operations: anion induced solvatochromism, New J. Chem. 38 (2014) 1484–1492. [8] X.J. Jiang, D.K. Ng, Sequential logic operations with a molecular keypad lock with four inputs and dual fluorescence outputs, Angew. Chem. Int. Ed. 53 (2014) 10481–10484. [9] Z.P. Dong, X.D. Le, P.P. Zhou, C.X. Dong, J.T. Ma, Sequential recognition of zinc ion and hydrogen sulfide by a new quinoline derivative with logic gate behavior, RSC Adv. 4 (2014) 18270–18277. [10] A.K. Mahapatra, S.K. Manna, C.D. Mukhopadhyay, D. Mandal, Pyrophosphate-selective fluorescent chemosensor based on ratiometric tripodal-Zn(II) complex: application in logic gates and living cells, Sensors Actuators B Chem. 200 (2014) 123–131. [11] S. Karmakar, S. Mardanya, S. Das, S. Baitalik, Efficient deep-blue emittier and molecular-scale memory device based on dipyridyl–phenylimidazole–terpyridine assembly, J. Phys. Chem. C 119 (2015) 6793–6805. [12] Q. Zou, X. Li, J.J. Zhang, J. Zhou, B.B. Sun, H. Tian, Unsymmetrical diarylethenes as molecular keypad locks with tunable photochromism and fluorescence via Cu2+ and CN− coordinations, Chem. Commun. 48 (2012) 2095–2097. [13] Y.Q. Tian, C.-Y. Chen, C.-C. Yang, A.C. Young, S.-H. Jang, W.-C. Chen, A.K.Y. Jen, 2-(2′Hydroxyphenyl)benzoxazole-containing two-photon-absorbing chromophores as sensors for zinc and hydroxide ions, Chem. Mater. 20 (2008) 1977–1987. [14] L. Wang, J.X. Yan, W.W. Qin, W.S. Liu, R. Wang, A new rhodamine-based single molecule multianalyte (Cu2+, Hg2+) sensor and its application in the biological system, Dyes Pigments 92 (2012) 1083–1090. [15] L.B. Zang, H.X. Shang, D.Y. Wei, S.M. Jiang, A multi-stimuli-responsive organogel based on salicylidene Schiff base, Sensors Actuators B Chem. 185 (2013) 389–397. [16] S.A. Lee, G.R. You, Y.W. Choi, H.Y. Jo, A.R. Kim, I. Noh, S.J. Kim, Y. Kim, C. Kim, A new multifunctional Schiff base as a fluorescence sensor for Al3+ and a colorimetric sensor for CN− in aqueous media: an application to bioimaging, Dalton Trans. 43 (2014) 6650–6659. [17] Y. Wang, Q. Zhao, L.B. Zang, C.S. Liang, S.M. Jiang, Discriminating detection of multiple analytes (F− and CN−) by a single probe through colorimetric and fluorescent dual channels, Dyes Pigments 123 (2015) 166–175. [18] C.-F. Wan, Y.-J. Chang, C.-Y. Chien, Y.-W. Sie, C.-H. Hu, A.-T. Wu, A new multifunctional Schiff base as a fluorescence sensor for Fe2+ and F− ions, and a colorimetric sensor for Fe3+, J. Lumin. 178 (2016) 115–120. [19] V.K. Gupta, N. Mergu, L.K. Kumawat, A.K. Singh, A reversible fluorescence "off-onoff" sensor for sequential detection of aluminum and acetate/fluoride ions, Talanta 144 (2015) 80–89. [20] I. Ravikumar, P. Ghosh, Zinc(II) and PPi selective fluorescence OFF-ON-OFF functionality of a chemosensor in physiological conditions, Inorg. Chem. 50 (2011) 4229–4231. [21] L.Y. Wang, L.L. Yang, L.B. Huang, D.R. Cao, Diketopyrrolopyrrole-derived Schiff base 3+ as colorimetric and fluoromertic probe for sequential detection of HSO− 4 and Fe with “off-on-off” response, Sensors Actuators B Chem. 209 (2015) 536–544. [22] Y.W. Choi, J.J. Lee, G.R. You, C. Kim, Fluorescence ‘on–off–on’ chemosensor for the sequential recognition of Hg2+ and cysteine in water, RSC Adv. 5 (2015) 38308–38315. [23] K.M. Vengaian, C.D. Britto, K. Sekar, G. Sivaraman, S. Singaravadivel, Fluorescence “on–off–on” chemosensor for selective detection of Hg2+ and S2−: application to bioimaging in living cells, RSC Adv. 6 (2016) 7668–7673.
273
[24] R.K. Pathak, K. Tabbasum, A. Rai, D. Panda, C.P. Rao, Pyrophosphate sensing by a fluorescent Zn2+ bound triazole linked imino-thiophenyl conjugate of calix[4]arene in HEPES buffer medium: spectroscopy, microscopy, and cellular studies, Anal. Chem. 84 (2012) 5117–5123. [25] M. Kumar, N. Kumar, V. Bhalla, A naphthalimide based chemosensor for Zn2+, pyrophosphate and H2O2: sequential logic operations at the molecular level, Chem. Commun. 49 (2013) 877–879. [26] R. Baron, A. Onopriyenko, E. Katz, O. Lioubashevski, I. Willner, S. Wang, H. Tian, An electrochemical/photochemical information processing system using a monolayerfunctionalized electrode, Chem. Commun. (2006) 2147–2149. [27] M. Kumar, A. Dhir, V. Bhalla, Molecular trafficking based on latch circuit, Chem. Commun. 46 (2010) 6744–6746. [28] G. de Ruiter, E. Tartakovsky, N. Oded, M.E. van der Boom, Sequential logic operations with surface-confined polypyridyl complexes displaying molecular random access memory features, Angew. Chem. Int. Ed. 49 (2010) 169–172. [29] U. Pischel, Advanced molecular logic with memory function, Angew. Chem. Int. Ed. 49 (2010) 1356–1358. [30] G. de Ruiter, L. Motiei, J. Choudhury, N. Oded, M.E. van der Boom, Electrically addressable multistate volatile memory with flip-flop and flip-flap-flop logic circuits on a solid support, Angew. Chem. Int. Ed. 49 (2010) 4780–4783. [31] S.C. Wang, G.W. Men, L.Y. Zhao, Q.F. Hou, S.M. Jiang, Binaphthyl-derived salicylidene Schiff base for dual-channel sensing of Cu, Zn cations and integrated molecular logic gates, Sensors Actuators B Chem. 145 (2010) 826–831. [32] S. Sharma, M.S. Hundal, G. Hundal, Dual channel chromo/fluorogenic chemosensors for cyanide and fluoride ions—an example of in situ acid catalysis of the Strecker reaction for cyanide ion chemodosimetry, Org. Biomol. Chem. 11 (2013) 654–661. [33] Y.S. Mi, Z. Cao, Y.T. Chen, S. Long, Q.F. Xie, D.M. Liang, W.P. Zhu, J.N. Xiang, A reversible switch as highly selective sequential chemosensor for Al3+ cation followed by F− anion, Sensors Actuators B Chem. 192 (2014) 164–172. [34] Y.-H. Zhao, X. Zeng, L. Mu, J. Li, C. Redshaw, G. Wei, A reversible and visible colorimetric/fluorescent chemosensor for Al3+ and F− ions with a Large Stoke's shift, Sensors Actuators B Chem. 204 (2014) 450–458. [35] Neeraj, A. Kumar, V. Kumar, R. Prajapati, S.K. Asthana, K.K.U. Upadhyay, J.Z. Zhao, A remarkable effect of N,N-diethylamino functionality on the optoelectronic properties of a salicylimine-based probe for Al 3+ , Dalton Trans. 43 (2014) 5831–5839. [36] Y.-S. Mi, D.-M. Liang, Y.-T. Chen, X.-B. Luo, J.-N. Xiang, A rhodamine–quinoline type molecular switch as a highly selective sequential sensor for Al3+ and F− in aqueous solution, RSC Adv. 4 (2014) 42337–42345. [37] B. Sen, M. Mukherjee, S. Banerjee, S. Pal, P. Chattopadhyay, A rhodamine-based 'turn-on' Al3+ ion-selective reporter and the resultant complex as a secondary sensor for F− ion are applicable to living cell staining, Dalton Trans. 44 (2015) 8708–8717. [38] S.B. Maity, P.K. Bharadwaj, A chemosensor built with rhodamine derivatives appended to an aromatic platform via 1,2,3-triazoles: dual detection of aluminum(III) and fluoride/acetate ions, Inorg. Chem. 52 (2013) 1161–1163. [39] Q.P. Diao, P.Y. Ma, L.L. Lv, T.C. Li, Y. Sun, X.H. Wang, D.Q. Song, A water-soluble and reversible fluorescent probe for Al3+ and F− in living cells, Sensors Actuators B Chem. 229 (2016) 138–144. [40] P. Torawane, K. Tayade, S. Bothra, S.K. Sahoo, N. Singh, A. Borse, A. Kuwar, A highly selective and sensitive fluorescent ‘turn-on’ chemosensor for Al3+ based on CN− isomerisation mechanism with nanomolar detection, Sensors Actuators B Chem. 222 (2016) 562–566. [41] C.S. Liang, W.H. Bu, C.L. Li, G.W. Men, M.Y. Deng, Y.K. Jiangyao, H.C. Sun, S.M. Jiang, A highly selective fluorescent sensor for Al3+ and the use of the resulting complex as a secondary sensor for PPi in aqueous media: its applicability in live cell imaging, Dalton Trans. 44 (2015) 11352–11359. [42] H.A. Benesi, J.H. Hildebrand, A spectrophotometric investigation of the interaction of iodine with aromatic hydrocarbons, J. Am. Chem. Soc. 71 (1949) 2703–2707. [43] Y.M. Hijji, B. Barare, A.P. Kennedy, R. Butcher, Synthesis and photophysical characterization of a Schiff base as anion sensor, Sensors Actuators B Chem. 136 (2009) 297–302. [44] I.G. Shenderovich, P.M. Tolstoy, N.S. Golubev, S.N. Smirnov, G.S. Denisov, H.H. Limbach, Low-temperature NMR studies of the structure and dynamics of a novel series of acid-base complexes of HF with collidine exhibiting scalar couplings across hydrogen bonds, J. Am. Chem. Soc. 125 (2003) 11710–11720. [45] L.B. Zang, D.Y. Wei, S.C. Wang, S.M. Jiang, A phenolic Schiff base for highly selective sensing of fluoride and cyanide via different channels, Tetrahedron 68 (2012) 636–641. [46] J.S. Wu, W.M. Liu, J.C. Ge, H.Y. Zhang, P.F. Wang, New sensing mechanisms for design of fluorescent chemosensors emerging in recent years, Chem. Soc. Rev. 40 (2011) 3483–3495. [47] J.S. Zugazagoitia, M. Maya, C. Damián-Zea, P. Navarro, H.I. Beltrán, J. Peon, Excitedstate dynamics and two-photon absorption cross sections of fluorescent diphenyltinIV derivatives with schiff bases: a comparative study of the effect of chelation from the ultrafast to the steady-state time scale, J. Phys. Chem. A (2010) 704–714. [48] S.D. Liu, L.W. Zhang, W.Y. Zan, X.J. Yao, Y. Yang, X. Liu, A novel HBT-based Schiff base for colorimetric detection of aluminum: synthesis, characterization, spectral and DFT computational studies, Sensors Actuators B Chem. 192 (2014) 386–392. [49] J. Wang, Y. Pang, A simple sensitive ESIPT on-off fluorescent sensor for selective detection of Al3+ in water, RSC Adv. 4 (2013) 5845–5848. [50] J.-C. Qin, Z.-Y. Yang, L. Fan, X.-Y. Cheng, T.-R. Li, B.-D. Wang, Design and synthesis of a chemosensor for the detection of Al3+ based on ESIPT, Anal. Methods 6 (2014) 7343–7348. [51] Š. Budzak, D. Jacquemin, Mechanism of fluorescence switching in one ESIPT-based Al3+ probe, J. Phys. Chem. B 120 (2016) 6730–6738.
274
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[52] J.S. Wu, W.M. Liu, X.Q. Zhuang, F. Wang, P.F. Wang, S.L. Tao, X.H. Zhang, S.K. Wu, S.T. Lee, Fluorescence turn on of coumarin derivatives by metal cations: a new signaling mechanism based on C_N isomerization, Org. Lett. 9 (2007) 33–36. [53] G.W. Men, C.R. Chen, S.T. Zhang, C.S. Liang, Y. Wang, M.Y. Deng, H.X. Shang, B. Yang, S.M. Jiang, A real-time fluorescent sensor specific to Mg2+: crystallographic evidence, DFT calculation and its use for quantitative determination of magnesium in drinking water, Dalton Trans. 44 (2015) 2755–2762.
Chunshuang Liang received her BSc degree in chemistry from Jilin University in 2012. 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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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa
Single sensor for multiple analytes in different optical channel: Applying for multi-ion response modulation Chunshuang Liang, Shimei Jiang ⁎ State Key Laboratory of Supramolecular Structure and Materials, Jilin University, 2699 Qianjin Avenue, Changchun 130012, PR China
a r t i c l e
i n f o
Article history: Received 2 February 2017 Received in revised form 12 April 2017 Accepted 16 April 2017 Available online 18 April 2017 Keywords: Multiple analytes Fluoride Aluminum ion Dual-channel Reversible Multi-state logic circuit
a b s t r a c t 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_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. © 2017 Elsevier B.V. All rights reserved.
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 “WriteRead-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
⁎ Corresponding author. E-mail address: [email protected] (S. Jiang).
http://dx.doi.org/10.1016/j.saa.2017.04.026 1386-1425/© 2017 Elsevier B.V. All rights reserved.
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 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 [31,32]. So it is possible to realize simultaneous recognition of different analytes by using their derivatives. Of numerous common cations and anions, Al3+ 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 recognition of Al3+ and/or F− are numerous [33–40]. Among them, some sensors for sequential recognition of Al3+ and F− have been studied [36–39]. To the best of our knowledge, a chemosensor system for Al3+ 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 fluorescent sensor for Al3+, then L-Al3+ ensemble was a subsequent fluorescent sensor for PPi [41]. In that case, Al3+ could act a pen and PPi act an eraser. The “off-on-off” sensing phenomenon caused by Al3+ and PPi is reversible in fluorescent channel. Herein, the reported receptor L has been improved to function as a simultaneous Al3+ and F− probe in different optical channel. The input of only F− or Al3+ 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 AlF3, which competes with the binding between the Schiff base and
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the ions. In such a functional circuit, both of the Al3+ and F− act two 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 multiwrite 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 80 V, 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. 2.2.1. Preparation and Characterization of Reagent Solutions A stock solution of L (1 mM) was prepared in DMSO. For the measurements of fluoride ion selectivity, solutions of different anions − − (10 mM) were prepared for F−, Cl−, Br−, I−, AcO−, H2PO− 4 , BF4 , NO3 as their tetrabutylammonium (TBA) salts in DMSO. 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 the measurements of Al3+ selectivity, solutions of different (10 mM) cations were prepared from AlCl3, BaCl2·2H2O, CaCl2, CdCl2·2.5H2O, CoCl2·6H2O, CrCl3·6H2O, CuCl2·2H2O, PbCl2, FeCl2·4H2O, FeCl3, HgCl2, KCl, MnCl2·4H2O, NaCl, NiCl2·6H2O, ZnCl2 and MgCl2·6H2O in H2O. Solutions containing L (10 μM) and the different cations (100 μM) were again prepared by appropriate dilution using
Fig. 1. Absorption spectra of L (50 μM) before and after addition of various anions (750 − − − − μM) of F−, Cl−, Br−, I−, AcO−, H2PO− 4 , HSO4 , ClO4 , NO3 and BF4 in DMSO. Inset: Color change observed upon the addition of F− to the solution of L.
DMSO and their fluorescence spectra were recorded for a common excitation wavelength of 365 nm. 2.2.2. Spectrophotometric and Spectrofluorimetric Titrations Stock solutions of L (1 mM) and TBAF (tetrabutyalammonium fluoride; 10 mM) were prepared in DMSO and of Al3+ (10 mM) by dissolving AlCl3 in H2O. Solutions 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. Solutions containing L (10 μM) and increasing concentrations of Al3+ (0–100 μM) were prepared by appropriate dilutions using DMSO and their emission spectra (450–650 nm) recorded for an excitation wavelength of 365 nm. 2.2.3. Job Plot Measurements 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 to 1.0. The absorbance at 448 nm was plotted against the molar fraction of F−. For Al3+, a series of solution containing L and Al3+ were prepared such that the total concentration of Al3+ and L was 20 μM. The mole fraction of Al3+ was varied from 0.1 to 1.0. The fluorescence intensity at 510 nm was plotted against the molar fraction of Al3+. 2.2.4. Determination of Fluorescence Quantum Yield for Al3+ Binding The quantum yield was measured at room temperature referenced to quinine sulfate in sulfuric acid aqueous solution (Фfr = 0.546) and calculated according to the following equation: Φfs ¼ Φfr
1−10−ArLr 1−10
−AsLs
N2s N2r
Ds Dr
where Фfs is the radiative quantum yield of the sample; Фfr is the radiative quantum yield of the standard; As and Ar are the absorbance of the sample and standard at the excitation wavelength, respectively; Ds and Dr are the integrated areas of the emission for sample and standard, respectively; Ls and Lr are the lengths of the absorption cells for the sample and standard test; and Ns and Nr are the indices of refraction of the sample and standard solutions (pure solvents were assumed), respectively. 2.2.5. Determination of Detection Limit for F− and Al3+ The limits of detection (DL) of L for F− and Al3+ were determined from the following equation: DL ¼ 3 σ=K
Fig. 2. Absorption spectra of L (50 μM) upon addition of increasing amounts of F− (0–900 μM) in DMSO. The arrows indicate the change in the absorbance intensity with the increased F− ions. Inset: absorbance at 448 nm versus the concentration of F− added.
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Fig. 3. 1H NMR spectra of L (2.5 mM, DMSO-d6) with the addition of TBAF (DMSO-d6 solution). (a) L only, (b) L + F− (0.5 mM), (c) L + F− (1.25 mM), (d) L + F− (2.5 mM), (e) L + F− (3.75 mM), (f) L + F− (5.0 mM), (g) L + F− (7.5 mM).
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Fig. 5. Fluorescence spectra of L (10 μM, λex = 420 nm) upon addition of increasing amounts of Al3+ ion (0–100 μM) in DMSO. The arrow indicates the change in the emission intensity with the increased Al3+ ions. Inset: intensity at 510 nm versus the concentration of Al3+ added.
where σ is the standard deviation of the blank solution; K is the slope of the calibration curve. The detection limit was calculated based on the absorption titration for F− and fluorescence titration for Al3+.
3. Results and Discussion
2.2.6. Determination of the Association Constants for F− and Al3+ with L Assuming in both cases a 1:1 equilibrium (confirmed by the Job plot measurements), both the spectrophotometric and spectrofluorimetric data were analysed to give Ka values using the Benesi-Hildebrand treatment [42]. Thus, for F− binding the Ka value was obtained by fitting the equation:
The selectivity of L towards the anions F−, Cl−, Br−, I−, AcO−, H2PO− 4 , − − − HSO− 4 , ClO4 , NO3 and BF4 was investigated in DMSO solution. Of these anions, only fluoride caused a noticeable color change from colorless to orangish immediately (Fig. 1). The color change was visible to the naked eye (inset in Fig. 1). No obvious color 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 nm which decreases in intensity on addition offluoride, while absorption near 448, 510 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 fluoride [43]. The detection limit was calculated to be 2.45 × 10−6 M with a linearity range from 0 to 50 μM for the response to fluoride (Fig. S1). The value of the binding constant found by Benesi-Hildebrand (B\\H) analysis [42] was 4.44 × 103 M−1 with a satisfactory correlation coefficient value (R2 = 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. To further elucidate the interaction between L and F−, 1H NMR spectra of L were measured in the presence of different amounts of F− in DMSO-d6 solution (Fig. 3). Upon the addition of fluoride, the signals at 14.49 ppm and 9.76 ppm (\\OHa and\\OHc) 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
1=ðA−Amin Þ ¼ 1=fKðAmax −Amin Þ ½ F− g þ 1=ðAmax −Amin Þ where Amax, Amin, and A are absorbance of L in the presence of F− at saturation, 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−Amin) against 1/[F−]. 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].
Fig. 4. Fluorescence spectra of L (10 μM) before and after addition of various metal ions (100 μM) of Al3+, Ba2+, Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Pb2+, Fe2+, Fe3+, Hg2+, K+, Mn2+, Na+, Ni2+, Zn2+ and Mg2+ in DMSO, λex = 420 nm. Inset: Fluorescence changes observed upon the addition of Al3+ to the solution of L.
3.1. Colorimetric Channel for Fluoride Sensing
Fig. 6. 1H NMR spectra of L (2.5 mM, DMSO-d6) with the addition of Al3+ (D2O solution). (A) L only, (B) L+ Al3+ (7.5 mM).
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Fig. 7. (a) Visual color changes and (b) spectral changes of L (50 μM) in colorimetric channel after adding F− (300 μM) and Al3+ (100 μM) alternately.
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 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 Aluminum Ion Sensing L 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 2 ) to an adjacent proton acceptor (\\C_O, \\N_) through a six-membered ring of hydrogen-bonding configuration. Recently, many studies have reported o-hydroxy Schiff bases as Al 3+ selective probe by describing inhibition of ESIPT as the key sensing mechanism [48–51]. In DMSO solution, the fluorescence emission intensity of L was recorded at 490 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 excitedstate intramolecular proton transfer (ESIPT). The addition of Al 3+ ion resulted in fuorescence at 510 nm, the system thus exhibiting an “off-on” emission. In the presence of Al 3+ , 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 cations (Ba2+, Ca 2+ , Cd 2+ , Co 2+, Cr3+ , Cu2+ , Pb 2+ , Fe 2+, Fe3+ , Hg 2+, K + , Mn2+ ,
Na+, Ni2+, Zn2+ and Mg2+) led to negligible fluorescence changes, as shown in Fig. 4. The solution of L containing Al3+ showed bright green fluorescence under 365 nm ultraviolet lamp irradiation (inset in Fig. 4). The selective fluorescence enhancement by Al3+ can be ascribed to both inhibition of C_N isomerization and chelation enhanced fluorescence (CHEF) [20,35,53]. Coordination of Al3+ 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. The sensitivity of L for Al3+ was studied by fluorescence titration, as shown in Fig. 5. The fluorescence was detectable down to very low concentrations of Al3+, the detection limit being 2.56 × 10−8 M with a linearity range from 0 to 10 μM (Fig. S5). The association constant was calculated to be 7.45 × 103 M−1 (R2 = 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 did not interfere with the detection of Al3+ by L. Only Cu2+ led to complete fluorescence quenching. L still had sufficient “turn-on” ratios for the detection of Al3+ in the presence of Fe2+, Fe3+ and Hg2+, in which cases the intensity increased about 38-fold, 9-fold and 71-fold, respectively. To gain a further understanding of interaction between L and Al3+, 1 H NMR spectra of L were measured in the absence and presence of Al3+ in DMSO-d6 solution (Fig. 6). When 3 equivalents of Al3+ were added to L, the \\OHa and \\OHc protons disappeared completely and many new peaks appeared. The proton Hb’ on imine group for L-Al3+ appeared at 8.93 ppm, and aromatic protons also could be found at other position remarkably upon Al3+ complexation (Fig. 6B). This result supported the formation of L-Al3+ complex under the participation of both O and N atoms.
Scheme 1. Graphic of the proposed mechanism of the dynamic switching of F− and Al3+ and corresponding photos in the daylight (left) and under UV lamp (right).
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Fig. 8. (a) Visual fluorescent changes and (b) spectral changes of L (50 μM) in fluorescent channel after adding F− (300 μM) and Al3+ (100 μM) alternately. λex = 420 nm.
3.3. Reversible Sensing Behavior
3.4. “Write-Read-Erase-Read” Function
According to the investigation mentioned above, L has a high selectivity for the detection of F− and Al3+ in colorimetric/fluorescent channel over the tested anions and cations, respectively. Inspired by the competition between the formation of AlF3 and the complexes of Al3+ or F− with the receptor L, we further investigated the dynamic switch behavior of L with F− and Al3+. As F− can combine with Al3+ to form AlF3 complex in a ratio of 3 to 1, 6 equivalents of F− or 2 equivalents of Al3+ were added each time. The reversible sensing behavior of L for F− was investigated using the colorimetric channel over three cycles by the addition of F− followed by that of Al3+. 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 appearing having a maximum at 510 nm. The subsequent addition of Al3+ caused the color to fade and the absorption band to disappear. Because Al3+ 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 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 sensor by alternately adding F− and Al3+ (Scheme 1, right part). Similarly, the reversible sensing behavior of L for Al3+ was investigated using the fluorescent channel over three cycles of the addition of Al3+ followed by F−. As shown in Fig. 8, after the addition of Al 3+ , coordination of L to Al 3+ produced a green fluorescence with a peak at 510 nm. Then, addition of F− resulted in fluorescence quenching. This result was due to the stronger combination ability of F− with Al 3+, which led to the dissociation of L-Al 3+ complex. The fluorescence was regenerated when more Al 3+ 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 sensor by alternately adding Al3+ and F− (Scheme 1, left part). To illustrate the optical reversible behavior, 1H NMR spectra of L, L + F− and L + F− + Al3+ 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\\OH groups. After adding 1 equivalent of Al3+ to the above mentioned L-F− complex, the chemical shift signals for protons on the CH_N and phenyl ring of L were shifted back. This observation indicated that a competition reaction occurred between Al3+ and F− with L due to the formation of AlF3 complex. These results established that L could be used repeatedly as a reversible sensor for sensing purposes.
It is important to note that L-F− was non-fluorescent and there was no absorbance at 510 nm in the solution of L-Al3+ (Scheme 1, Figs. S9–S10). That is to say, the absorbance at 510 nm appeared only in the presence of L-F−, while the emission at 510 nm appeared only in the presence of L-Al3+. Thus, the addition of F− to the solution of L only caused a color change from colorless to orangish, while no fluorescence changes could be observed. Similarly, the addition of Al3+ to the solution of L only caused a green fluorescence enhancement, while no obvious color changes were observed. The addition of Al3+ to the solution of L-F− and the addition of F− to the solution of L- Al3+ resulted in the dissociation of the corresponding complex and release of free L. These results indicated that L could be developed as a reversible off-on-off sensor by alternately adding F− and Al3+ in the colorimetric channel, while it could also be developed as a reversible off-on-off sensor by alternately adding Al3+ 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 color change from colorless to orangish, the color disappeared after adding of Al3+ due to the formation of the AlF3 complex and releasing the free L, which is colorless and non-fluorescent. At this time, if Al3+ were added, the free L was able to bind with Al3+ and thereafter green fluorescence appeared. Finally, addition of F− resulted in fluorescence quenching. By controlling the addition order of F− and Al3+, the reversible signals can not only be implemented in a single colorimetric or fluorescent channel (Figs. 7 and 8), but also can be interpenetrated between the two channels (Fig. 10). This reversible sensing behavior could mimic a logic circuit (consists of two INHIBIT gates), depending upon the different chemical inputs
Fig. 9. 1H NMR spectra of L (2.5 mM), L + F− (7.5 mM), and L + F− + Al3+ (2.5 mM).
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Fig. 10. (a) Dual channel changes after addition of F− and Al3+ sequentially into the solution of L. (b) Reversible cyclic behavior of L upon the sequential addition of F− and Al3+; 1 = L; 2 = [1 + F−]; 3 = [2 + Al3+]; 4 = [3 + Al3+]; 5 = [4 + F−], F− is 3 equivalents to Al3+.
Fig. 11. (a) Truth Table for logic circuit, where 0 = Off and 1 = On signals. (b) Logic circuit with two inputs and two outputs.
(Al3+ 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 above, the emission at 510 nm (OUT1) appeared only under the addition of Al3+ (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 follows (Fig. 12). When Al3+ 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 = 1). In this case, Al3+ 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 the stored encoded information can be “erased” by adding Al3+ as reset input (IN1 = 1). F− acts as a pen and Al3+ acts as an eraser in colorimetric channel. Both of Al3+ and F− have double roles that can write as well as erase information, signals can be 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 = 0, OUT2 = 0 as the “OFF” state). Al3+/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
Fig. 12. Schematic representation of the reversible logic operations for a memory element possessing “write-read-erase-read” functions.
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. On the other hand, this sensor can enable fluorescent detection of Al3+ selectively due to the inhibition of C_N isomerization, cation-induced inhibition of ESIPT and CHEF. L behaves as a reversible switch by sequential input of F− and Al3+, 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 multichannel ion recognition and advanced logic gates.
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Acknowledgements This work was supported by the National Natural Science Foundation of China (21374036 and 51673082). Appendix A. Supplementary Data Supplementary data to this article can be found online at http://dx. doi.org/10.1016/j.saa.2017.04.026. References [1] X. Zhou, X. Wu, J. Yoon, A dual FRET based fluorescent probe as a multiple logic system, Chem. Commun. 51 (2015) 111–113. [2] V. García, A. Fernández-Lodeiro, R. Lamelas, A. Macías, R. Bastida, E. Bértolo, C. Núñez, Novel chromogenic macrocyclic molecular probes with logic gate function using anion/cation inputs, Dyes Pigments 110 (2014) 143–151. [3] M. Orłowska, A.M. Kłonkowski, J. Jezierska, J. Ryl, Luminescence recognition material as an INHIBIT logic gate in presence of Pb2+ and Cu2+ ions in aqueous solutions, Sensors Actuators B Chem. 186 (2013) 396–406. [4] S. Mardanya, S. Karmakar, S. Das, S. Baitalik, Anion and cation triggered modulation of optical properties of a pyridyl-imidazole receptor rigidly linked to pyrene and construction of INHIBIT, OR and XOR molecular logic gates: a combined experimental and DFT/TD-DFT investigation, Sensors Actuators B Chem. 206 (2015) 701–713. [5] K.-C. Chang, I.-H. Su, Y.-Y. Wang, W.-S. Chung, A bifunctional chromogenic calix[4]arene chemosensor for both cations and anions: a potential Ca2+ and F− switched INHIBIT logic gate with a YES logic function, Eur. J. Org. Chem. (2010) 4700–4704. [6] V. Luxami, A.S. Gupta, K. Paul, Dansyl–antipyrine dyad as a fluorescent sensor for Cu2+ and F−: sequential XNOR logic operation, New J. Chem. 38 (2014) 2841–2846. [7] N. Madhuprasad, J.R. Swathi, U.K. Manjunatha, A.N. Das, D.R. Shetty, Trivedi, dual colorimetric receptor with logic gate operations: anion induced solvatochromism, New J. Chem. 38 (2014) 1484–1492. [8] X.J. Jiang, D.K. Ng, Sequential logic operations with a molecular keypad lock with four inputs and dual fluorescence outputs, Angew. Chem. Int. Ed. 53 (2014) 10481–10484. [9] Z.P. Dong, X.D. Le, P.P. Zhou, C.X. Dong, J.T. Ma, Sequential recognition of zinc ion and hydrogen sulfide by a new quinoline derivative with logic gate behavior, RSC Adv. 4 (2014) 18270–18277. [10] A.K. Mahapatra, S.K. Manna, C.D. Mukhopadhyay, D. Mandal, Pyrophosphate-selective fluorescent chemosensor based on ratiometric tripodal-Zn(II) complex: application in logic gates and living cells, Sensors Actuators B Chem. 200 (2014) 123–131. [11] S. Karmakar, S. Mardanya, S. Das, S. Baitalik, Efficient deep-blue emittier and molecular-scale memory device based on dipyridyl–phenylimidazole–terpyridine assembly, J. Phys. Chem. C 119 (2015) 6793–6805. [12] Q. Zou, X. Li, J.J. Zhang, J. Zhou, B.B. Sun, H. Tian, Unsymmetrical diarylethenes as molecular keypad locks with tunable photochromism and fluorescence via Cu2+ and CN− coordinations, Chem. Commun. 48 (2012) 2095–2097. [13] Y.Q. Tian, C.-Y. Chen, C.-C. Yang, A.C. Young, S.-H. Jang, W.-C. Chen, A.K.Y. Jen, 2-(2′Hydroxyphenyl)benzoxazole-containing two-photon-absorbing chromophores as sensors for zinc and hydroxide ions, Chem. Mater. 20 (2008) 1977–1987. [14] L. Wang, J.X. Yan, W.W. Qin, W.S. Liu, R. Wang, A new rhodamine-based single molecule multianalyte (Cu2+, Hg2+) sensor and its application in the biological system, Dyes Pigments 92 (2012) 1083–1090. [15] L.B. Zang, H.X. Shang, D.Y. Wei, S.M. Jiang, A multi-stimuli-responsive organogel based on salicylidene Schiff base, Sensors Actuators B Chem. 185 (2013) 389–397. [16] S.A. Lee, G.R. You, Y.W. Choi, H.Y. Jo, A.R. Kim, I. Noh, S.J. Kim, Y. Kim, C. Kim, A new multifunctional Schiff base as a fluorescence sensor for Al3+ and a colorimetric sensor for CN− in aqueous media: an application to bioimaging, Dalton Trans. 43 (2014) 6650–6659. [17] Y. Wang, Q. Zhao, L.B. Zang, C.S. Liang, S.M. Jiang, Discriminating detection of multiple analytes (F− and CN−) by a single probe through colorimetric and fluorescent dual channels, Dyes Pigments 123 (2015) 166–175. [18] C.-F. Wan, Y.-J. Chang, C.-Y. Chien, Y.-W. Sie, C.-H. Hu, A.-T. Wu, A new multifunctional Schiff base as a fluorescence sensor for Fe2+ and F− ions, and a colorimetric sensor for Fe3+, J. Lumin. 178 (2016) 115–120. [19] V.K. Gupta, N. Mergu, L.K. Kumawat, A.K. Singh, A reversible fluorescence "off-onoff" sensor for sequential detection of aluminum and acetate/fluoride ions, Talanta 144 (2015) 80–89. [20] I. Ravikumar, P. Ghosh, Zinc(II) and PPi selective fluorescence OFF-ON-OFF functionality of a chemosensor in physiological conditions, Inorg. Chem. 50 (2011) 4229–4231. [21] L.Y. Wang, L.L. Yang, L.B. Huang, D.R. Cao, Diketopyrrolopyrrole-derived Schiff base 3+ as colorimetric and fluoromertic probe for sequential detection of HSO− 4 and Fe with “off-on-off” response, Sensors Actuators B Chem. 209 (2015) 536–544. [22] Y.W. Choi, J.J. Lee, G.R. You, C. Kim, Fluorescence ‘on–off–on’ chemosensor for the sequential recognition of Hg2+ and cysteine in water, RSC Adv. 5 (2015) 38308–38315. [23] K.M. Vengaian, C.D. Britto, K. Sekar, G. Sivaraman, S. Singaravadivel, Fluorescence “on–off–on” chemosensor for selective detection of Hg2+ and S2−: application to bioimaging in living cells, RSC Adv. 6 (2016) 7668–7673.
273
[24] R.K. Pathak, K. Tabbasum, A. Rai, D. Panda, C.P. Rao, Pyrophosphate sensing by a fluorescent Zn2+ bound triazole linked imino-thiophenyl conjugate of calix[4]arene in HEPES buffer medium: spectroscopy, microscopy, and cellular studies, Anal. Chem. 84 (2012) 5117–5123. [25] M. Kumar, N. Kumar, V. Bhalla, A naphthalimide based chemosensor for Zn2+, pyrophosphate and H2O2: sequential logic operations at the molecular level, Chem. Commun. 49 (2013) 877–879. [26] R. Baron, A. Onopriyenko, E. Katz, O. Lioubashevski, I. Willner, S. Wang, H. Tian, An electrochemical/photochemical information processing system using a monolayerfunctionalized electrode, Chem. Commun. (2006) 2147–2149. [27] M. Kumar, A. Dhir, V. Bhalla, Molecular trafficking based on latch circuit, Chem. Commun. 46 (2010) 6744–6746. [28] G. de Ruiter, E. Tartakovsky, N. Oded, M.E. van der Boom, Sequential logic operations with surface-confined polypyridyl complexes displaying molecular random access memory features, Angew. Chem. Int. Ed. 49 (2010) 169–172. [29] U. Pischel, Advanced molecular logic with memory function, Angew. Chem. Int. Ed. 49 (2010) 1356–1358. [30] G. de Ruiter, L. Motiei, J. Choudhury, N. Oded, M.E. van der Boom, Electrically addressable multistate volatile memory with flip-flop and flip-flap-flop logic circuits on a solid support, Angew. Chem. Int. Ed. 49 (2010) 4780–4783. [31] S.C. Wang, G.W. Men, L.Y. Zhao, Q.F. Hou, S.M. Jiang, Binaphthyl-derived salicylidene Schiff base for dual-channel sensing of Cu, Zn cations and integrated molecular logic gates, Sensors Actuators B Chem. 145 (2010) 826–831. [32] S. Sharma, M.S. Hundal, G. Hundal, Dual channel chromo/fluorogenic chemosensors for cyanide and fluoride ions—an example of in situ acid catalysis of the Strecker reaction for cyanide ion chemodosimetry, Org. Biomol. Chem. 11 (2013) 654–661. [33] Y.S. Mi, Z. Cao, Y.T. Chen, S. Long, Q.F. Xie, D.M. Liang, W.P. Zhu, J.N. Xiang, A reversible switch as highly selective sequential chemosensor for Al3+ cation followed by F− anion, Sensors Actuators B Chem. 192 (2014) 164–172. [34] Y.-H. Zhao, X. Zeng, L. Mu, J. Li, C. Redshaw, G. Wei, A reversible and visible colorimetric/fluorescent chemosensor for Al3+ and F− ions with a Large Stoke's shift, Sensors Actuators B Chem. 204 (2014) 450–458. [35] Neeraj, A. Kumar, V. Kumar, R. Prajapati, S.K. Asthana, K.K.U. Upadhyay, J.Z. Zhao, A remarkable effect of N,N-diethylamino functionality on the optoelectronic properties of a salicylimine-based probe for Al 3+ , Dalton Trans. 43 (2014) 5831–5839. [36] Y.-S. Mi, D.-M. Liang, Y.-T. Chen, X.-B. Luo, J.-N. Xiang, A rhodamine–quinoline type molecular switch as a highly selective sequential sensor for Al3+ and F− in aqueous solution, RSC Adv. 4 (2014) 42337–42345. [37] B. Sen, M. Mukherjee, S. Banerjee, S. Pal, P. Chattopadhyay, A rhodamine-based 'turn-on' Al3+ ion-selective reporter and the resultant complex as a secondary sensor for F− ion are applicable to living cell staining, Dalton Trans. 44 (2015) 8708–8717. [38] S.B. Maity, P.K. Bharadwaj, A chemosensor built with rhodamine derivatives appended to an aromatic platform via 1,2,3-triazoles: dual detection of aluminum(III) and fluoride/acetate ions, Inorg. Chem. 52 (2013) 1161–1163. [39] Q.P. Diao, P.Y. Ma, L.L. Lv, T.C. Li, Y. Sun, X.H. Wang, D.Q. Song, A water-soluble and reversible fluorescent probe for Al3+ and F− in living cells, Sensors Actuators B Chem. 229 (2016) 138–144. [40] P. Torawane, K. Tayade, S. Bothra, S.K. Sahoo, N. Singh, A. Borse, A. Kuwar, A highly selective and sensitive fluorescent ‘turn-on’ chemosensor for Al3+ based on CN− isomerisation mechanism with nanomolar detection, Sensors Actuators B Chem. 222 (2016) 562–566. [41] C.S. Liang, W.H. Bu, C.L. Li, G.W. Men, M.Y. Deng, Y.K. Jiangyao, H.C. Sun, S.M. Jiang, A highly selective fluorescent sensor for Al3+ and the use of the resulting complex as a secondary sensor for PPi in aqueous media: its applicability in live cell imaging, Dalton Trans. 44 (2015) 11352–11359. [42] H.A. Benesi, J.H. Hildebrand, A spectrophotometric investigation of the interaction of iodine with aromatic hydrocarbons, J. Am. Chem. Soc. 71 (1949) 2703–2707. [43] Y.M. Hijji, B. Barare, A.P. Kennedy, R. Butcher, Synthesis and photophysical characterization of a Schiff base as anion sensor, Sensors Actuators B Chem. 136 (2009) 297–302. [44] I.G. Shenderovich, P.M. Tolstoy, N.S. Golubev, S.N. Smirnov, G.S. Denisov, H.H. Limbach, Low-temperature NMR studies of the structure and dynamics of a novel series of acid-base complexes of HF with collidine exhibiting scalar couplings across hydrogen bonds, J. Am. Chem. Soc. 125 (2003) 11710–11720. [45] L.B. Zang, D.Y. Wei, S.C. Wang, S.M. Jiang, A phenolic Schiff base for highly selective sensing of fluoride and cyanide via different channels, Tetrahedron 68 (2012) 636–641. [46] J.S. Wu, W.M. Liu, J.C. Ge, H.Y. Zhang, P.F. Wang, New sensing mechanisms for design of fluorescent chemosensors emerging in recent years, Chem. Soc. Rev. 40 (2011) 3483–3495. [47] J.S. Zugazagoitia, M. Maya, C. Damián-Zea, P. Navarro, H.I. Beltrán, J. Peon, Excitedstate dynamics and two-photon absorption cross sections of fluorescent diphenyltinIV derivatives with schiff bases: a comparative study of the effect of chelation from the ultrafast to the steady-state time scale, J. Phys. Chem. A (2010) 704–714. [48] S.D. Liu, L.W. Zhang, W.Y. Zan, X.J. Yao, Y. Yang, X. Liu, A novel HBT-based Schiff base for colorimetric detection of aluminum: synthesis, characterization, spectral and DFT computational studies, Sensors Actuators B Chem. 192 (2014) 386–392. [49] J. Wang, Y. Pang, A simple sensitive ESIPT on-off fluorescent sensor for selective detection of Al3+ in water, RSC Adv. 4 (2013) 5845–5848. [50] J.-C. Qin, Z.-Y. Yang, L. Fan, X.-Y. Cheng, T.-R. Li, B.-D. Wang, Design and synthesis of a chemosensor for the detection of Al3+ based on ESIPT, Anal. Methods 6 (2014) 7343–7348. [51] Š. Budzak, D. Jacquemin, Mechanism of fluorescence switching in one ESIPT-based Al3+ probe, J. Phys. Chem. B 120 (2016) 6730–6738.
274
C. Liang, S. Jiang / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 183 (2017) 267–274
[52] J.S. Wu, W.M. Liu, X.Q. Zhuang, F. Wang, P.F. Wang, S.L. Tao, X.H. Zhang, S.K. Wu, S.T. Lee, Fluorescence turn on of coumarin derivatives by metal cations: a new signaling mechanism based on C_N isomerization, Org. Lett. 9 (2007) 33–36. [53] G.W. Men, C.R. Chen, S.T. Zhang, C.S. Liang, Y. Wang, M.Y. Deng, H.X. Shang, B. Yang, S.M. Jiang, A real-time fluorescent sensor specific to Mg2+: crystallographic evidence, DFT calculation and its use for quantitative determination of magnesium in drinking water, Dalton Trans. 44 (2015) 2755–2762.
Chunshuang Liang received her BSc degree in chemistry from Jilin University in 2012. 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.