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A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion
Journal Pre-proofs Research paper A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion Liwei Xiao, Lilei Ren, Xuemin Jing, Zheng Li, Shaoguang Wu, Dingyi Guo PII: DOI: Reference:
S0020-1693(19)30959-4 https://doi.org/10.1016/j.ica.2019.119207 ICA 119207
To appear in:
Inorganica Chimica Acta
Received Date: Revised Date: Accepted Date:
2 July 2019 8 October 2019 14 October 2019
Please cite this article as: L. Xiao, L. Ren, X. Jing, Z. Li, S. Wu, D. Guo, A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion, Inorganica Chimica Acta (2019), doi: https:// doi.org/10.1016/j.ica.2019.119207
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion Liwei Xiao*, Lilei Ren, Xuemin Jing, Zheng Li,Shaoguang Wu, Dingyi Guo School of Chemistry and Material Science, Langfang Normal University, Langfang 065000, P.R. China Abstract An unique colorimetric/fluorometric probe L for detection of fluoride ion have been developed by introducing naphthaldehyde to 1,8-naphthalimide framework. The striking color change from yellow to blue, fluorescent quenching of probe can be observed only in the presence of fluoride ions in DMSO-water(volume ratio7:1) solution. The probe L bound to fluoride ion in a 1:1 stoichiometric manner, and the detection limit of L towards fluoride ion was up to 8.06×10-7 mol L-1. 1H NMR titration indicates that the probe undergoes the deprotonation of N-H group through hydrogen bond interaction between naphthyl hydrazine and fluoride ions. Keywords Colorimetric; fluoride ion sensor; naked-eye-detection; 1,8-naphthalimide
1. Introduction Fluoride as the smallest anion and one of the most fascinating anions is widely present in organisms and natural environment, and it plays important roles in chemical, biological, medical processes and daily life. For example, fluoride ion is utilised for the treatment of dental care, osteoporosis, anesthetics and psychiatric drugs[1-2] However, excess intake of fluoride ion is hazardous, which can lead to fluorosis, thyroid activity depression, bone disorders and kidney failure[3-5]. Hence, how to effectively recognize and sense fluoride ions have attracted considerable attention for human health care and environment 1
protection. Fluorescent probe and colorimetric sensors are suitable method for these application by virtue of the simplicity, high sensitivity, high selectivity and nonintrusive detection. Especially, colorimetric sensors have some obvious advantages than other methods, such as its
*Corresponding authors. E-mail addresses: [email protected] (L. Xiao); [email protected](L. Xiao)
convenience, good visualization and low cost. Among the existing fluorescent probes and colorimetric sensors, The main strategies have been utilized for optical detection of fluoride include: hydrogen bonding between
fluoride
complexation[16-23],
and
N-H
fluoride
or
O-H
mediated
hydrogen[6-15],
desilylation[24-29],
boron-fluoride organotin
based
multidentate Lewis acids-fluoride complexation[30-31]. Futhermore, fluoride could induce selective cleavage of oxygen-phosphorus or oxygen-sulfur bonds[32-33], and some complexes such as ruthenium complexes were also employed for fluoride detection[34].We have synthesized some sesors based Schiff base for detection fluoride ion[35-37], and all of them recognize the fluoride through hydrogen bonding interaction. 1,8-naphthalimide derivatives have been widely used as fluorophores in fluorescence detection and live cell imagining because of their excellent optical properties, such as high quantum yields, good photostability and large Stokes’ shift[38-39]. 4-amino-1,8-naphthalimide derivatives are often used in the design fluoride probe, in which the -NH position is a very sensitive binding site to F– through F– and N-H interaction[13-14]. Herein, we describe a novel, selective and sensitive colorimetric and fluorescent fluoride probe containing 1,8-naphthalimide (Scheme 1), the probe was based on the 2
interaction between F- and 9-anthraldehyde hydrazone N-H, and the probe features a fast response of color change and fluorescent quenching signal after interaction with fluoride. （Scheme 1）
2. Experiments 2.1. Materials and instrumentation All reagents were purchased from Aladdin Shanghai reagent company and used without further purification unless otherwise noted. The anion reagents were used as their tetrabutylammonium salts, and bases were used as t-Bu3COK and NaOH. 1H
NMR and
13C
NMR spectra were collected on a Bruker Avance II 400 MHz
spectrometer. FT-IR spectra were measured on a Shimadzu IR Prestige-21 spectrometer. HRMS were measured by using a Shimadzu LCMS-IT-TOF spectrometer. UV–vis spectra were recorded on a Shimadzu UV-2550 spectrometer. Fluorescence spectra were carried out using a Hitachi F-4600 fluorescence spectrophotometer. The processed data and titration plots were obtained by Origin software. 2.2 The synthesis of receptor L 9-Anthracenecarboxaldehyde
(0.206g,
1.0mmol)
and
(N-butyl-1,8-
naphthalimide)hydrazine (0.342 g, 1.2 mmol) were mixed in absolute ethanol (10 mL), and one drop of acetic acid was added to the mixture. Then it was heated to 80oC, and refluxed for 6 h with stirring, After the reaction finished, the mixture was cooled to room temperature and filter under vacuum. The filter cake was dried and purified by recrystallization with ethanol to obtain the desired product L as red solid
0.314g,
yield 64.2%. m.p.245~247℃; 1H NMR (400MHz, DMSO-d6) δ 11.66 (s, 1H), 9.69 (s, 1H), 8.82 (dd, J = 8.5, 4.0 Hz, 3H), 8.69 (s, 1H), 8.47 (d, J = 7.2 Hz, 1H), 8.37 (d, J = 8.4 Hz, 1H), 8.16 (d, J = 8.4 Hz, 2H), 7.81 (t, J = 7.8 Hz, 1H), 7.69 (t, J = 8.1 Hz, 3H), 7.65 – 7.56 (m, 2H), 4.02 (t, J = 7.3 Hz, 2H), 1.74 –1.52 (m, 2H), 1.36 (dt, J = 14.7, 7.3 Hz, 2H), 0.93 (t, J = 7.3 Hz, 3H).
13C
3
NMR (101MHz, DMSO-d6) δ 164.12,
143.69, 134.13, 131.53, 130.00, 129.76, 129.59, 127.72, 126.04, 125.74, 125.58, 125.25, 40.02, 39.82, 39.61, 39.40, 30.27, 20.32, 14.21. IR(KBr): 2705, 1653, 701cm-1. HRMS: m/z calcd for C31H26N3O2: [M+H]+ 472.1947, found: 472.1961 2.3 General procedure for the spectroscopic studies The sensor L(2×10−4molL−1) solution was prepared in DMSO-H2O(volume ratio7:1) aqueous solution. Anions(F–, Cl–, Br–, I–, H2PO4–, AcO–, HSO4– and ClO4–solutions were prepared from tetrabutylammonium salt (TBA) at the concentration of 0.1 mol L−1 in DMSO-H2O(volume ratio7:1)solution. Both L(1mL) and anions (0.2mL) stock solution were transfered to 10 mL volumetric flask and dissolved in DMSO-H2O solution to make a solution to 10 mL accurately. So the concentration diluted to 2.0×10−5 molL−1. Different TBA salts were added to the probe solution and their corresponding UV–vis and fluorescence spectra were recorded at room temperature. The excitation wavelength was 466 nm, the negative pressure was 500 V, and the slit width was 10 nm. 2.4 Titrations experiments UV–vis and fluorescence titration experiments were carried out at ambient temperature. To 2×10-5molL-1DMSO-H2O solution of the sensor L, varying equivalents of different anions were added separately and the spectra were measured. For each mixture the fluorescence response was measured after 30 min mixed. For 1H NMR titrations, the solution of L(1×10-3molL-1) was titrated with fluoride anion by addition of increasing equivalents of F− in DMSO d6. Varying equivalents of F– was added to the solution of L and 1H NMR spectra was recorded after each addition.
3 . Results and discussions 3.1 Solvent selection Anions in biological tissues are present in aqueous solutions rather than organic solvents, thus it is more meaningful to study the anions sensing works in aqueous solution. But sensor L is insoluble in water and soluble in DMSO, so the 4
properties of L were tested in DMSO-H2O mixed solvent. It was found that the solubility of L decreased significantly when the water content in mixed solvents exceeded 15%. Therefore, DMSO-H2O(volume ratio 7:1) mixed solvent was chosen as experimental solvent. 3.2 Colorimetric identification The anion sensing behavior of the sensor L towards different anions such as F–, Cl–, Br–, I–, H2PO4–, AcO–, HSO4– and ClO4–in DMSO-H2O solution was investigated with naked-eye and UV light. Under ambient light(Fig. 1), an obvious color change from yellow to blue was observed in the presence of fluoride ion, while the others have almost no significant color changes. Under UV light(Fig. 2), a discernible color change from orange to non-fluorescent blue occurred when fluoride ion was added, while other anions did not induce color change. These results indicated that L could be used as an effective colorimetric for F–. （Fig .1） （Fig .2） 3.3 Absorption and fluorescence spectra Furtherly, The optical behavior of sensor L in response to various species including F–, Cl–, Br–, I–, H2PO4–, AcO–, HSO4– and ClO4–were investigated with UV–vis and fluorescence spectra in DMSO-H2O mixed solution. As shown in Fig. 3, free sensor showed strong absorption bands centered at 460nm. Upon addition of F–, the maximum absorption peak was red-shifted to 630 nm accompanied with the emergence of a new band centered at 364 nm. Furthermore, with incremental addition of F–, the fluorescence intensity of the band centered at 556 nm decreased gradually to 1/14(Fig.4). As illustrated in Fig.3 and Fig.4, only F– could induce distinct spectroscopic changes while none of noticeable changes were observed upon addition of any other anions. In brief, the phenomenon observed under ambient light and UV irradiation by 5
naked-eye was consistent with the UV-vis and fluorescent spectra changes. Therefore, The sensor L could be served as a colorimetric/fluorometric dual-channel probe for specific detection of F–. （Fig .3） （Fig .4） 3.4 UV–vis Absorption and Fluorescence Spectroscopy Titrations In order to further investigate the sensing ability of the sensor L, spectroscopy titration experiment was carried out. Fig.5 displayed the UV–vis absorption titrations of the sensor L with addition of various amount of fluoride ion in DMSO-H2O mixed solution. Upon addition of F–, the main absorption band centered at 460 nm decreased gradually with concomitant appearance of an increased absorption band centered at 630 nm. The location of isosbestic points appeared at 511.6 nm. Furthermore, the systematic changes in emission spectra of L on addition of F– in DMSO-H2O mixed solution was depicted in Fig.6, The emission peak at 556 nm decreased gradually with increasing equivalents of F–(0-5.0 equiv.).Interestingly, the fluorescence intensity was linearly dependent on the concentration of F– (Fig.7). The linear equation is: Y=-111.09X+1655.195, R2=0.9918. The detection limit of L towards F– was calculated to be 8.06×10-7 mol L-1, according to 3σ method. It can be seen from the titration experiment, the sensor L was sensitive to fluotide ion with a real-time fluorescent response. （Fig .5） （Fig .6） （Fig .7） 3.5 Binding mode of receptor with fluoride ions As shown in Fig.8, the fluorescence was changed linearly upon the following addition of fluoride ions. To investigate the binding mode of L and F–, the job’s plot experiment was carried out. The decreaseing tendency of emission intensity for the complex between L and F–slowed down at molar fraction of ca.0.5, indicating that the 6
complex ratio of L and F– is 1:1. （Fig .8） 3.6 Selectivity and Competition Experiments To explore the selectivity of L for sensing F–, the cross-contamination experiments were performed. When other competing anions(Cl–, Br–, I–, AcO–, HSO4–, H2PO4–,ClO4–) were added to the L-F– complex step by step, the complex still exhibited obvious fluorescence quenching (Fig.9). These result demonstrated that the detection of L towards F– was not influenced significantly by other coexisting anions. Therefore, it can be undoubtedly announceed that L can be served as a good selective fluorescent probe for F–. （Fig .9） 3.7 1H NMR titrations 1H
NMR titration is an important means to reveal the intermolecular interaction.
It was found that the signal strength of proton on the hydrazide (11.66ppm) weakened when addition of 0.5 equiv. of F– and signal disappeared drastically upon addition of 1.0 equiv. of F-(Fig.10). No further changes were observed when 2.0 equiv. of F- was added, indicating a 1:1 stoichiometry manner between L and F–. The other aromatic proton was up field shifted by some extent, which was ascribed to the increase in the electron density around the aromatic system. （Fig .10) 1H
NMR titration between L and bases (OH–and t-Bu3CO–) were carried out
furtherly, in order to elucidate the interaction mechanism between L and anion. The hydrazide proton signal weakens gradually with the increase of alkali addition. As shown in Fig11, the proton signal disappears nearly when the 2 equiv. t-Bu3CO– was added. However, OH– is relatively weaker in alkalinity, and its ability to capture protons is weaker than that of t-Bu3CO–. Therefore, it is necessary to add more OH– to eliminate proton signals( Fig12). 7
The interaction between L and F– is similar to that of L with OH– and t-Bu3CO–, which is essentially a proton transfer process between Brnsted-Lowry acids and bases. With the addition of F– to L, proton transfering occurs between L and F–. The deprotonation of the N-H group in L blocked the excited-state intramolecular proton transfer(ESIPT) process[12,32], reorganized the intramolecular electron transfer process across the entire molecule[20-21], causing fluorescence quenching and other character change. A proposed binding model was provided as shown in Scheme 2. （Fig .11) （Fig .12) （Scheme 2) 4. Conclusion In
summary,
a
novel
colorimetric
and
fluorescent
probe
based-on
1,8-naphthalimide was synthesized. The sensor L could be served as a naked-eye chemosensor for detection of F–with a significant color change from yellow to blue. Additionally, fluorescence intensity was substantially reduced upon addition of F–. These result suggested that sensor L might be a dual channel sensor for detection of fluorine ion. Efforts toward replacing the 1,8-naphthalimide fluorophore with other dye such as rhodamine, boron–dipyrromethane (BODIPY), coumarin etc have been in progress in our laboratory. Ackowlegements: Authors thank the financial support from program of Hebei education department(ZD2016046) and Langfang science and technology bureau (2019011018), China
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[5] M.S. Zafar, N. Ahmed, Fluoride 48 (3) (2015) 184. [6]Y. Zhang, X. Yang, G. Sun, et al., Spectrochim. Acta Part A 199 (2018) 161 [7]Z.-Y. Li , H.-K. Su, H.-X. Tong, et al., Spectrochim. Acta Part A 200(2018) 307 [8]V. Reena, S. Suganya, S. Velmathi, J. Fluorine Chem., 153(2013)89 [9]Y. Wang, Q. Zhao, L. Zang, et al., Dyes Pigments123 (2015)166 [10]Y. Feng, X. Li, H. Ma, et al., Dyes Pigments153 (2018)200 [11]X. Cao, N. Zhao, H. Lv, et al., Sens. Actuat. B 266 (2018) 637 [12]G. G. V. Kumar, M. P. Kesavan, G. Sivaraman, et al., Sens. Actuat. B, 255(3) (2018) 3194. [13]X. Yuan, C.-X. Zhao, Y.-X. Lu, et al., J. Photoch. Photobio. A 361 (2018)41. [14]X. Chen, T. Leng, C. Wang, et al., Dyes Pigments141 (2017)299 [15]S. Ghosh, M. A. Alam, A. Ganguly, et al., Inorg. Chim. Acta 429 (2015) 39 [16] F. Cheng, E.M. Bonder, F. Jakle, J. Am. Chem. Soc. 135 (2013),17286. [17] X.-L. Liu, M. Mao, M.-G. Ren, et al., Sens. Actuators B 200(2014) 317. [18]G .R. Kumar, P. Thilagar, Dalton Trans., 43(2014) 7200. [19]T. W. Hudnall, C.-W. Chiu, F. P. Gabbal, Accounts Chem. Res.42( 2)(2009)388. [20]M. Yuan, X. Du, Z. Liu, et al., Chem. Eur. J. 24(37)(2018) 9211. [21]W. Che, G. Li, J. Zhang, et al., J. Photoch. Photobio. A 358 (2018)274. [22]A. Kawachi, A. Tani, J. Shimada, et al., J. Am. Chem. Soc. 130(2008)4222. [23] M.-S. Yuan, Q.Wang, W.-J. Wang, et al., Analyst 139(2014) 1541. [24]Y. Shen, X. Zhang, Y. Zhang, et al., Sens. Actuat. B 258 (2018) 544. [25]S. Liu, L. Zhang, P. Zhou, et al., Sens. Actuat B 255(1) (2018)401. [26]Y. Zhou, M.-M. Liu, J-Y Li, et al, Dyes Pigments 158 (2018) 277. [27]S. Jiao, X Wang, Y Sun, et al., Sens. Actuat. B 262(2018)188. [28]X. Shi, W. Fan, C. Fan, et al., Dyes Pigments 140(2017) 109. [29]Q. Yang, C. Jia, Q. Chen, et al., J. Mater. Chem. B, 5(10) (2017) 2002. [30]S. Chandra, A. Růžička, P. Švec, et al, Anal. Chim. Acta 577 (2006) 91. [31]M. M. Naseer, K. Jurkschat, Chem. Commun.53(2017)8122. [32]A. Pandey, A. Kumar, S. Vishwakarma, et al., Chem. Select 3(2018) 3444. [33] M. Du, B. Huo, J. Liu, et al., Anal Chim Acta 1030( 2018)172. [34]S. J. Butler, Chem. Commun. 51 (2015)10879. [35]Z. Li, S Wang, L Xiao, et al., Inorg Chim Acta 479(2018) 148. 9
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Scheme and Figure captions: Scheme 1 Synthesis of the sensor L Scheme 2 A binding model between L and FFig .1 The color change of the DMSO-H2O(7:1)mixed solusion of L with addition of various anions under ambient light Fig .2 The color change of the DMSO-H2O(7:1)mixed solusion of L with addition of various anions under UV light Fig.3 UV-vis absorption spectra of the sensor L upon addition of different anions (50 equiv.) in DMSO-H2O(7:1)mixed solusion Fig.4The fluorescence spectra of L upon addition of different anions in DMSO-H2O(7:1)mixed solusion (50 equiv) Fig.5 The UV-vis spectra of L upon addition of different equivalent F– in DMSO-H2O (7:1)mixed solusion Fig.6 The fluorescence spectra of L upon addition different equivalent F– in DMSO-H2O(7:1)mixed solusion (0-5eq.) Fig.7 Relationship between emission intensity(556nm) and the concentration of F– Fig. 8 Job’s plot for the complex of F– with L determined by fluorescence spectra Fig.9 Fluorescence intensity of receptor upon the addition of various anions in DMSO-H2O(7:1)mixed solusion Fig.10
11H
NMR spectra of L to which different amounts of fluoride anion have
been added. Fig.11 11H NMR spectra of L to which different amounts of t-Bu3CO– have been added. Fig.12 11H NMR spectra of L to which different amounts of OH–have been added.
11
O
C 4H 9 O
N
O
O C 4H 9
AcOH, reflux
H N N
O
NHNH2
+ H 2O
N L
Scheme. 1 Synthesis of the sensor L
O
N
C4H9
C4H9
C4H9 O
O
N
O
O
F
N
O
HF e
HN
F N
N
N H
N
N
Scheme 2 A binding model between L and F– L L+HSO4-
L+Br-
L+I-
L+Cl-
L+ F-
L+ ClO4-
L+AcO- L+H2PO4
Fig .1 The color change of the DMSO-H2O(7:1)mixed solusion of L with addition of various anions under ambient light L L+HSO4-
L+Br-
L+I-
L+Cl-
L+F-
L+ClO4-
L+AcO-
L+H2PO4-
Fig .2 The color change of the DMSO-H2O mixed(7:1) solusion of L with addition of various anions under UV light
12
-
Probe L and other anions
0.5
F-
Probe L BrCH3COO-
0.4
Cl-
Absorbance(a.u.)
ClO4-
0.3
HSO4 IH2PO4-
0.2
F-
0.1 0.0 300
400
500
600
700
800
Wavelengty(nm)
Fig.3 UV-vis absorption spectra of the sensor L upon addition of different
anions (50 equiv.) in DMSO-H2O(7:1)mixed solusion
2000
BrAcOH2PO4-
fluorescence intensity（a.u.）
Probe L and other anions
ClO4-
1500
FHSO4IProbe L
1000
500
-
F
0
450
500
550
600
650
700
750
800
wavelength(nm)
Fig.4 The fluorescence spectra of L upon addition of different anions (50 equiv) in DMSO-H2O(7:1)mixed solusion
13
0.5
F-
0-5eq
Absorbance(a.u.)
0.4
0.3
0-5eq
0.2
0.1
0.0 300
400
500
600
700
800
Wevelength(nm)
Fig.5 The UV-vis spectra of L upon addition of different equivalent F–in DMSO-H2O(7:1) mixed solusion 1800
F-
fluorescence intensity（a.u.）
1600 1400
0—5eq
1200 1000 800 600 400 200 0 400
450
500
550
600
650
700
750
800
Wavelength(nm)
Fig.6 The fluorescence spectra of L upon addition different equivalent F–in DMSO-H2O(7:1)mixed solusion(0-5eq.)
14
fluorescence intensity（a.u.）
1700 1600 1500 1400 1300 1200 1100 0
1
2 3 [F-]/[receptor L
4
5
Fig.7 Relationship between emission intensity(556nm) and the concentration of F–
fluorescence intensity（a.u.）
1000 900 800 700 600 500
0.0
0.2
0.4 0.6 [F-]:（[F-]+[2a]）
0.8
1.0
Fig. 8 Job’s plot for the complex of F– with L determined by fluorescence spectra
15
receptor+ions receptor+ions+F-
2000 1800
fluorscence intensity
1600 1400 1200 1000 800 600 400 200 0
Br-
AcO-
Cl-
ClO4-
HSO4-
I-
H2PO4-
F-
Fig.9 Fluorescence intensity of receptor upon the addition of various anions in DMSO-H2O(7:1)mixed solusion
Fig.10
11H
NMR spectra of L to which different amounts of fluoride anion have
been added.
16
Fig.11 11H NMR spectra of L to which different amounts of t-Bu3CO– have been added.
Fig.12 11H NMR spectra of L to which different amounts of OH–have been added.
Conflict of interest
We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the 17
criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us. We confirm that we have given due consideration to the protection of intellectual property associated with this work and that there are no impediments to publication, including the timing of publication, with respect to intellectual property. In so doing we confirm that we have followed the regulations of our institutions concerning intellectual property. We understand that the Corresponding Author is the sole contact for the Editorial process. He/she is responsible for communicating with the other authors about progress, submissions of revisions and final approval of proofs. We confirm that we have provided a current, correct email address which is accessible by the Corresponding Author and which has been configured to accept email from [email protected]. Signed by the corresponding author on behalf of all co-authors: Prof. Liwei Xiao College of Chemistry and Materials Science, Langfang Normal University, Langfang 065000, P.R. China; Email: [email protected]
Graphical Abstract A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion Liwei Xiao*, Lilei Ren, Xuemin Jing, Zheng Li,Shaoguang Wu, Dingyi Guo
An unique colorimetric/fluorometric probe for detection of fluoride ion have been developed by introducing naphthaldehyde to 1,8-naphthalimide framework. 18
C4H9
C4H9 O
N
O
O
N
O
F
-HF H
N N
e
Fluorescent quenching
N N
Blue solution
Yellow solution
Highlights An unique colorimetric/fluorometric sensor L for detection of fluoride ion have been developed by introducing naphthaldehyde to 1,8-naphthalimide framework. The striking color change from yellow to blue, fluorescent quenching of probe can be observed only in the presence of fluoride ions in DMAO-water(Volume ratio7:1) solution. The sensor L bound to F-in a 1:1 stoichiometric manner, and the detection limit of L towards fluoride ion was up to 8.06×10-7 mol L-1.
19
S0020-1693(19)30959-4 https://doi.org/10.1016/j.ica.2019.119207 ICA 119207
To appear in:
Inorganica Chimica Acta
Received Date: Revised Date: Accepted Date:
2 July 2019 8 October 2019 14 October 2019
Please cite this article as: L. Xiao, L. Ren, X. Jing, Z. Li, S. Wu, D. Guo, A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion, Inorganica Chimica Acta (2019), doi: https:// doi.org/10.1016/j.ica.2019.119207
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion Liwei Xiao*, Lilei Ren, Xuemin Jing, Zheng Li,Shaoguang Wu, Dingyi Guo School of Chemistry and Material Science, Langfang Normal University, Langfang 065000, P.R. China Abstract An unique colorimetric/fluorometric probe L for detection of fluoride ion have been developed by introducing naphthaldehyde to 1,8-naphthalimide framework. The striking color change from yellow to blue, fluorescent quenching of probe can be observed only in the presence of fluoride ions in DMSO-water(volume ratio7:1) solution. The probe L bound to fluoride ion in a 1:1 stoichiometric manner, and the detection limit of L towards fluoride ion was up to 8.06×10-7 mol L-1. 1H NMR titration indicates that the probe undergoes the deprotonation of N-H group through hydrogen bond interaction between naphthyl hydrazine and fluoride ions. Keywords Colorimetric; fluoride ion sensor; naked-eye-detection; 1,8-naphthalimide
1. Introduction Fluoride as the smallest anion and one of the most fascinating anions is widely present in organisms and natural environment, and it plays important roles in chemical, biological, medical processes and daily life. For example, fluoride ion is utilised for the treatment of dental care, osteoporosis, anesthetics and psychiatric drugs[1-2] However, excess intake of fluoride ion is hazardous, which can lead to fluorosis, thyroid activity depression, bone disorders and kidney failure[3-5]. Hence, how to effectively recognize and sense fluoride ions have attracted considerable attention for human health care and environment 1
protection. Fluorescent probe and colorimetric sensors are suitable method for these application by virtue of the simplicity, high sensitivity, high selectivity and nonintrusive detection. Especially, colorimetric sensors have some obvious advantages than other methods, such as its
*Corresponding authors. E-mail addresses: [email protected] (L. Xiao); [email protected](L. Xiao)
convenience, good visualization and low cost. Among the existing fluorescent probes and colorimetric sensors, The main strategies have been utilized for optical detection of fluoride include: hydrogen bonding between
fluoride
complexation[16-23],
and
N-H
fluoride
or
O-H
mediated
hydrogen[6-15],
desilylation[24-29],
boron-fluoride organotin
based
multidentate Lewis acids-fluoride complexation[30-31]. Futhermore, fluoride could induce selective cleavage of oxygen-phosphorus or oxygen-sulfur bonds[32-33], and some complexes such as ruthenium complexes were also employed for fluoride detection[34].We have synthesized some sesors based Schiff base for detection fluoride ion[35-37], and all of them recognize the fluoride through hydrogen bonding interaction. 1,8-naphthalimide derivatives have been widely used as fluorophores in fluorescence detection and live cell imagining because of their excellent optical properties, such as high quantum yields, good photostability and large Stokes’ shift[38-39]. 4-amino-1,8-naphthalimide derivatives are often used in the design fluoride probe, in which the -NH position is a very sensitive binding site to F– through F– and N-H interaction[13-14]. Herein, we describe a novel, selective and sensitive colorimetric and fluorescent fluoride probe containing 1,8-naphthalimide (Scheme 1), the probe was based on the 2
interaction between F- and 9-anthraldehyde hydrazone N-H, and the probe features a fast response of color change and fluorescent quenching signal after interaction with fluoride. （Scheme 1）
2. Experiments 2.1. Materials and instrumentation All reagents were purchased from Aladdin Shanghai reagent company and used without further purification unless otherwise noted. The anion reagents were used as their tetrabutylammonium salts, and bases were used as t-Bu3COK and NaOH. 1H
NMR and
13C
NMR spectra were collected on a Bruker Avance II 400 MHz
spectrometer. FT-IR spectra were measured on a Shimadzu IR Prestige-21 spectrometer. HRMS were measured by using a Shimadzu LCMS-IT-TOF spectrometer. UV–vis spectra were recorded on a Shimadzu UV-2550 spectrometer. Fluorescence spectra were carried out using a Hitachi F-4600 fluorescence spectrophotometer. The processed data and titration plots were obtained by Origin software. 2.2 The synthesis of receptor L 9-Anthracenecarboxaldehyde
(0.206g,
1.0mmol)
and
(N-butyl-1,8-
naphthalimide)hydrazine (0.342 g, 1.2 mmol) were mixed in absolute ethanol (10 mL), and one drop of acetic acid was added to the mixture. Then it was heated to 80oC, and refluxed for 6 h with stirring, After the reaction finished, the mixture was cooled to room temperature and filter under vacuum. The filter cake was dried and purified by recrystallization with ethanol to obtain the desired product L as red solid
0.314g,
yield 64.2%. m.p.245~247℃; 1H NMR (400MHz, DMSO-d6) δ 11.66 (s, 1H), 9.69 (s, 1H), 8.82 (dd, J = 8.5, 4.0 Hz, 3H), 8.69 (s, 1H), 8.47 (d, J = 7.2 Hz, 1H), 8.37 (d, J = 8.4 Hz, 1H), 8.16 (d, J = 8.4 Hz, 2H), 7.81 (t, J = 7.8 Hz, 1H), 7.69 (t, J = 8.1 Hz, 3H), 7.65 – 7.56 (m, 2H), 4.02 (t, J = 7.3 Hz, 2H), 1.74 –1.52 (m, 2H), 1.36 (dt, J = 14.7, 7.3 Hz, 2H), 0.93 (t, J = 7.3 Hz, 3H).
13C
3
NMR (101MHz, DMSO-d6) δ 164.12,
143.69, 134.13, 131.53, 130.00, 129.76, 129.59, 127.72, 126.04, 125.74, 125.58, 125.25, 40.02, 39.82, 39.61, 39.40, 30.27, 20.32, 14.21. IR(KBr): 2705, 1653, 701cm-1. HRMS: m/z calcd for C31H26N3O2: [M+H]+ 472.1947, found: 472.1961 2.3 General procedure for the spectroscopic studies The sensor L(2×10−4molL−1) solution was prepared in DMSO-H2O(volume ratio7:1) aqueous solution. Anions(F–, Cl–, Br–, I–, H2PO4–, AcO–, HSO4– and ClO4–solutions were prepared from tetrabutylammonium salt (TBA) at the concentration of 0.1 mol L−1 in DMSO-H2O(volume ratio7:1)solution. Both L(1mL) and anions (0.2mL) stock solution were transfered to 10 mL volumetric flask and dissolved in DMSO-H2O solution to make a solution to 10 mL accurately. So the concentration diluted to 2.0×10−5 molL−1. Different TBA salts were added to the probe solution and their corresponding UV–vis and fluorescence spectra were recorded at room temperature. The excitation wavelength was 466 nm, the negative pressure was 500 V, and the slit width was 10 nm. 2.4 Titrations experiments UV–vis and fluorescence titration experiments were carried out at ambient temperature. To 2×10-5molL-1DMSO-H2O solution of the sensor L, varying equivalents of different anions were added separately and the spectra were measured. For each mixture the fluorescence response was measured after 30 min mixed. For 1H NMR titrations, the solution of L(1×10-3molL-1) was titrated with fluoride anion by addition of increasing equivalents of F− in DMSO d6. Varying equivalents of F– was added to the solution of L and 1H NMR spectra was recorded after each addition.
3 . Results and discussions 3.1 Solvent selection Anions in biological tissues are present in aqueous solutions rather than organic solvents, thus it is more meaningful to study the anions sensing works in aqueous solution. But sensor L is insoluble in water and soluble in DMSO, so the 4
properties of L were tested in DMSO-H2O mixed solvent. It was found that the solubility of L decreased significantly when the water content in mixed solvents exceeded 15%. Therefore, DMSO-H2O(volume ratio 7:1) mixed solvent was chosen as experimental solvent. 3.2 Colorimetric identification The anion sensing behavior of the sensor L towards different anions such as F–, Cl–, Br–, I–, H2PO4–, AcO–, HSO4– and ClO4–in DMSO-H2O solution was investigated with naked-eye and UV light. Under ambient light(Fig. 1), an obvious color change from yellow to blue was observed in the presence of fluoride ion, while the others have almost no significant color changes. Under UV light(Fig. 2), a discernible color change from orange to non-fluorescent blue occurred when fluoride ion was added, while other anions did not induce color change. These results indicated that L could be used as an effective colorimetric for F–. （Fig .1） （Fig .2） 3.3 Absorption and fluorescence spectra Furtherly, The optical behavior of sensor L in response to various species including F–, Cl–, Br–, I–, H2PO4–, AcO–, HSO4– and ClO4–were investigated with UV–vis and fluorescence spectra in DMSO-H2O mixed solution. As shown in Fig. 3, free sensor showed strong absorption bands centered at 460nm. Upon addition of F–, the maximum absorption peak was red-shifted to 630 nm accompanied with the emergence of a new band centered at 364 nm. Furthermore, with incremental addition of F–, the fluorescence intensity of the band centered at 556 nm decreased gradually to 1/14(Fig.4). As illustrated in Fig.3 and Fig.4, only F– could induce distinct spectroscopic changes while none of noticeable changes were observed upon addition of any other anions. In brief, the phenomenon observed under ambient light and UV irradiation by 5
naked-eye was consistent with the UV-vis and fluorescent spectra changes. Therefore, The sensor L could be served as a colorimetric/fluorometric dual-channel probe for specific detection of F–. （Fig .3） （Fig .4） 3.4 UV–vis Absorption and Fluorescence Spectroscopy Titrations In order to further investigate the sensing ability of the sensor L, spectroscopy titration experiment was carried out. Fig.5 displayed the UV–vis absorption titrations of the sensor L with addition of various amount of fluoride ion in DMSO-H2O mixed solution. Upon addition of F–, the main absorption band centered at 460 nm decreased gradually with concomitant appearance of an increased absorption band centered at 630 nm. The location of isosbestic points appeared at 511.6 nm. Furthermore, the systematic changes in emission spectra of L on addition of F– in DMSO-H2O mixed solution was depicted in Fig.6, The emission peak at 556 nm decreased gradually with increasing equivalents of F–(0-5.0 equiv.).Interestingly, the fluorescence intensity was linearly dependent on the concentration of F– (Fig.7). The linear equation is: Y=-111.09X+1655.195, R2=0.9918. The detection limit of L towards F– was calculated to be 8.06×10-7 mol L-1, according to 3σ method. It can be seen from the titration experiment, the sensor L was sensitive to fluotide ion with a real-time fluorescent response. （Fig .5） （Fig .6） （Fig .7） 3.5 Binding mode of receptor with fluoride ions As shown in Fig.8, the fluorescence was changed linearly upon the following addition of fluoride ions. To investigate the binding mode of L and F–, the job’s plot experiment was carried out. The decreaseing tendency of emission intensity for the complex between L and F–slowed down at molar fraction of ca.0.5, indicating that the 6
complex ratio of L and F– is 1:1. （Fig .8） 3.6 Selectivity and Competition Experiments To explore the selectivity of L for sensing F–, the cross-contamination experiments were performed. When other competing anions(Cl–, Br–, I–, AcO–, HSO4–, H2PO4–,ClO4–) were added to the L-F– complex step by step, the complex still exhibited obvious fluorescence quenching (Fig.9). These result demonstrated that the detection of L towards F– was not influenced significantly by other coexisting anions. Therefore, it can be undoubtedly announceed that L can be served as a good selective fluorescent probe for F–. （Fig .9） 3.7 1H NMR titrations 1H
NMR titration is an important means to reveal the intermolecular interaction.
It was found that the signal strength of proton on the hydrazide (11.66ppm) weakened when addition of 0.5 equiv. of F– and signal disappeared drastically upon addition of 1.0 equiv. of F-(Fig.10). No further changes were observed when 2.0 equiv. of F- was added, indicating a 1:1 stoichiometry manner between L and F–. The other aromatic proton was up field shifted by some extent, which was ascribed to the increase in the electron density around the aromatic system. （Fig .10) 1H
NMR titration between L and bases (OH–and t-Bu3CO–) were carried out
furtherly, in order to elucidate the interaction mechanism between L and anion. The hydrazide proton signal weakens gradually with the increase of alkali addition. As shown in Fig11, the proton signal disappears nearly when the 2 equiv. t-Bu3CO– was added. However, OH– is relatively weaker in alkalinity, and its ability to capture protons is weaker than that of t-Bu3CO–. Therefore, it is necessary to add more OH– to eliminate proton signals( Fig12). 7
The interaction between L and F– is similar to that of L with OH– and t-Bu3CO–, which is essentially a proton transfer process between Brnsted-Lowry acids and bases. With the addition of F– to L, proton transfering occurs between L and F–. The deprotonation of the N-H group in L blocked the excited-state intramolecular proton transfer(ESIPT) process[12,32], reorganized the intramolecular electron transfer process across the entire molecule[20-21], causing fluorescence quenching and other character change. A proposed binding model was provided as shown in Scheme 2. （Fig .11) （Fig .12) （Scheme 2) 4. Conclusion In
summary,
a
novel
colorimetric
and
fluorescent
probe
based-on
1,8-naphthalimide was synthesized. The sensor L could be served as a naked-eye chemosensor for detection of F–with a significant color change from yellow to blue. Additionally, fluorescence intensity was substantially reduced upon addition of F–. These result suggested that sensor L might be a dual channel sensor for detection of fluorine ion. Efforts toward replacing the 1,8-naphthalimide fluorophore with other dye such as rhodamine, boron–dipyrromethane (BODIPY), coumarin etc have been in progress in our laboratory. Ackowlegements: Authors thank the financial support from program of Hebei education department(ZD2016046) and Langfang science and technology bureau (2019011018), China
References. [1] S. Kumar, R. Saini, D. Kaur, Sens. Actuators B 160 (2011) 705. [2] X. Zhuang, W. Liu, J. Wu, et al., Spectrochim. Acta A 79 (2011) 1352. [3] Y. Lu, Z.R. Sun, L.N. Wu, et al., Fluoride 33 (2) (2000) 74. [4] S. Ayoob, A.K. Gupta, Crit. Rev. Environ. Sci. Technol. 36 (6) (2006) 433. 8
[5] M.S. Zafar, N. Ahmed, Fluoride 48 (3) (2015) 184. [6]Y. Zhang, X. Yang, G. Sun, et al., Spectrochim. Acta Part A 199 (2018) 161 [7]Z.-Y. Li , H.-K. Su, H.-X. Tong, et al., Spectrochim. Acta Part A 200(2018) 307 [8]V. Reena, S. Suganya, S. Velmathi, J. Fluorine Chem., 153(2013)89 [9]Y. Wang, Q. Zhao, L. Zang, et al., Dyes Pigments123 (2015)166 [10]Y. Feng, X. Li, H. Ma, et al., Dyes Pigments153 (2018)200 [11]X. Cao, N. Zhao, H. Lv, et al., Sens. Actuat. B 266 (2018) 637 [12]G. G. V. Kumar, M. P. Kesavan, G. Sivaraman, et al., Sens. Actuat. B, 255(3) (2018) 3194. [13]X. Yuan, C.-X. Zhao, Y.-X. Lu, et al., J. Photoch. Photobio. A 361 (2018)41. [14]X. Chen, T. Leng, C. Wang, et al., Dyes Pigments141 (2017)299 [15]S. Ghosh, M. A. Alam, A. Ganguly, et al., Inorg. Chim. Acta 429 (2015) 39 [16] F. Cheng, E.M. Bonder, F. Jakle, J. Am. Chem. Soc. 135 (2013),17286. [17] X.-L. Liu, M. Mao, M.-G. Ren, et al., Sens. Actuators B 200(2014) 317. [18]G .R. Kumar, P. Thilagar, Dalton Trans., 43(2014) 7200. [19]T. W. Hudnall, C.-W. Chiu, F. P. Gabbal, Accounts Chem. Res.42( 2)(2009)388. [20]M. Yuan, X. Du, Z. Liu, et al., Chem. Eur. J. 24(37)(2018) 9211. [21]W. Che, G. Li, J. Zhang, et al., J. Photoch. Photobio. A 358 (2018)274. [22]A. Kawachi, A. Tani, J. Shimada, et al., J. Am. Chem. Soc. 130(2008)4222. [23] M.-S. Yuan, Q.Wang, W.-J. Wang, et al., Analyst 139(2014) 1541. [24]Y. Shen, X. Zhang, Y. Zhang, et al., Sens. Actuat. B 258 (2018) 544. [25]S. Liu, L. Zhang, P. Zhou, et al., Sens. Actuat B 255(1) (2018)401. [26]Y. Zhou, M.-M. Liu, J-Y Li, et al, Dyes Pigments 158 (2018) 277. [27]S. Jiao, X Wang, Y Sun, et al., Sens. Actuat. B 262(2018)188. [28]X. Shi, W. Fan, C. Fan, et al., Dyes Pigments 140(2017) 109. [29]Q. Yang, C. Jia, Q. Chen, et al., J. Mater. Chem. B, 5(10) (2017) 2002. [30]S. Chandra, A. Růžička, P. Švec, et al, Anal. Chim. Acta 577 (2006) 91. [31]M. M. Naseer, K. Jurkschat, Chem. Commun.53(2017)8122. [32]A. Pandey, A. Kumar, S. Vishwakarma, et al., Chem. Select 3(2018) 3444. [33] M. Du, B. Huo, J. Liu, et al., Anal Chim Acta 1030( 2018)172. [34]S. J. Butler, Chem. Commun. 51 (2015)10879. [35]Z. Li, S Wang, L Xiao, et al., Inorg Chim Acta 479(2018) 148. 9
[36]Z. Li, S Wang , L. Xiao, et al., Inorg Chim Acta 476(2018)7. [37]Z. Li, C. Liu, S. Wang, et al., Spectrochim. Acta Part A 210 (2019)321. [38] C. Liu, J. Xu, F. Yang, et al., Sens. Actuat. B 212(2015) 364. [39]Y. Fu, C. Fan, G. Liu, et al., Sens., Actuat B 239 (2017) 295.
10
Scheme and Figure captions: Scheme 1 Synthesis of the sensor L Scheme 2 A binding model between L and FFig .1 The color change of the DMSO-H2O(7:1)mixed solusion of L with addition of various anions under ambient light Fig .2 The color change of the DMSO-H2O(7:1)mixed solusion of L with addition of various anions under UV light Fig.3 UV-vis absorption spectra of the sensor L upon addition of different anions (50 equiv.) in DMSO-H2O(7:1)mixed solusion Fig.4The fluorescence spectra of L upon addition of different anions in DMSO-H2O(7:1)mixed solusion (50 equiv) Fig.5 The UV-vis spectra of L upon addition of different equivalent F– in DMSO-H2O (7:1)mixed solusion Fig.6 The fluorescence spectra of L upon addition different equivalent F– in DMSO-H2O(7:1)mixed solusion (0-5eq.) Fig.7 Relationship between emission intensity(556nm) and the concentration of F– Fig. 8 Job’s plot for the complex of F– with L determined by fluorescence spectra Fig.9 Fluorescence intensity of receptor upon the addition of various anions in DMSO-H2O(7:1)mixed solusion Fig.10
11H
NMR spectra of L to which different amounts of fluoride anion have
been added. Fig.11 11H NMR spectra of L to which different amounts of t-Bu3CO– have been added. Fig.12 11H NMR spectra of L to which different amounts of OH–have been added.
11
O
C 4H 9 O
N
O
O C 4H 9
AcOH, reflux
H N N
O
NHNH2
+ H 2O
N L
Scheme. 1 Synthesis of the sensor L
O
N
C4H9
C4H9
C4H9 O
O
N
O
O
F
N
O
HF e
HN
F N
N
N H
N
N
Scheme 2 A binding model between L and F– L L+HSO4-
L+Br-
L+I-
L+Cl-
L+ F-
L+ ClO4-
L+AcO- L+H2PO4
Fig .1 The color change of the DMSO-H2O(7:1)mixed solusion of L with addition of various anions under ambient light L L+HSO4-
L+Br-
L+I-
L+Cl-
L+F-
L+ClO4-
L+AcO-
L+H2PO4-
Fig .2 The color change of the DMSO-H2O mixed(7:1) solusion of L with addition of various anions under UV light
12
-
Probe L and other anions
0.5
F-
Probe L BrCH3COO-
0.4
Cl-
Absorbance(a.u.)
ClO4-
0.3
HSO4 IH2PO4-
0.2
F-
0.1 0.0 300
400
500
600
700
800
Wavelengty(nm)
Fig.3 UV-vis absorption spectra of the sensor L upon addition of different
anions (50 equiv.) in DMSO-H2O(7:1)mixed solusion
2000
BrAcOH2PO4-
fluorescence intensity（a.u.）
Probe L and other anions
ClO4-
1500
FHSO4IProbe L
1000
500
-
F
0
450
500
550
600
650
700
750
800
wavelength(nm)
Fig.4 The fluorescence spectra of L upon addition of different anions (50 equiv) in DMSO-H2O(7:1)mixed solusion
13
0.5
F-
0-5eq
Absorbance(a.u.)
0.4
0.3
0-5eq
0.2
0.1
0.0 300
400
500
600
700
800
Wevelength(nm)
Fig.5 The UV-vis spectra of L upon addition of different equivalent F–in DMSO-H2O(7:1) mixed solusion 1800
F-
fluorescence intensity（a.u.）
1600 1400
0—5eq
1200 1000 800 600 400 200 0 400
450
500
550
600
650
700
750
800
Wavelength(nm)
Fig.6 The fluorescence spectra of L upon addition different equivalent F–in DMSO-H2O(7:1)mixed solusion(0-5eq.)
14
fluorescence intensity（a.u.）
1700 1600 1500 1400 1300 1200 1100 0
1
2 3 [F-]/[receptor L
4
5
Fig.7 Relationship between emission intensity(556nm) and the concentration of F–
fluorescence intensity（a.u.）
1000 900 800 700 600 500
0.0
0.2
0.4 0.6 [F-]:（[F-]+[2a]）
0.8
1.0
Fig. 8 Job’s plot for the complex of F– with L determined by fluorescence spectra
15
receptor+ions receptor+ions+F-
2000 1800
fluorscence intensity
1600 1400 1200 1000 800 600 400 200 0
Br-
AcO-
Cl-
ClO4-
HSO4-
I-
H2PO4-
F-
Fig.9 Fluorescence intensity of receptor upon the addition of various anions in DMSO-H2O(7:1)mixed solusion
Fig.10
11H
NMR spectra of L to which different amounts of fluoride anion have
been added.
16
Fig.11 11H NMR spectra of L to which different amounts of t-Bu3CO– have been added.
Fig.12 11H NMR spectra of L to which different amounts of OH–have been added.
Conflict of interest
We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome. We confirm that the manuscript has been read and approved by all named authors and that there are no other persons who satisfied the 17
criteria for authorship but are not listed. We further confirm that the order of authors listed in the manuscript has been approved by all of us. We confirm that we have given due consideration to the protection of intellectual property associated with this work and that there are no impediments to publication, including the timing of publication, with respect to intellectual property. In so doing we confirm that we have followed the regulations of our institutions concerning intellectual property. We understand that the Corresponding Author is the sole contact for the Editorial process. He/she is responsible for communicating with the other authors about progress, submissions of revisions and final approval of proofs. We confirm that we have provided a current, correct email address which is accessible by the Corresponding Author and which has been configured to accept email from [email protected]. Signed by the corresponding author on behalf of all co-authors: Prof. Liwei Xiao College of Chemistry and Materials Science, Langfang Normal University, Langfang 065000, P.R. China; Email: [email protected]
Graphical Abstract A selective naphthalimide-based colorimetric and fluorescent chemosensor for “naked-eye” detection of fluoride ion Liwei Xiao*, Lilei Ren, Xuemin Jing, Zheng Li,Shaoguang Wu, Dingyi Guo
An unique colorimetric/fluorometric probe for detection of fluoride ion have been developed by introducing naphthaldehyde to 1,8-naphthalimide framework. 18
C4H9
C4H9 O
N
O
O
N
O
F
-HF H
N N
e
Fluorescent quenching
N N
Blue solution
Yellow solution
Highlights An unique colorimetric/fluorometric sensor L for detection of fluoride ion have been developed by introducing naphthaldehyde to 1,8-naphthalimide framework. The striking color change from yellow to blue, fluorescent quenching of probe can be observed only in the presence of fluoride ions in DMAO-water(Volume ratio7:1) solution. The sensor L bound to F-in a 1:1 stoichiometric manner, and the detection limit of L towards fluoride ion was up to 8.06×10-7 mol L-1.
19