Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 121 (2014) 514–519
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A highly selective fluorescent chemosensor for iron ion based on 1H-imidazo [4,5-b] phenazine derivative Guo-ying Gao, Wen-juan Qu, Bing-bing Shi, Peng Zhang, Qi Lin, Hong Yao, Wen-long Yang, You-ming Zhang, Tai-bao Wei ⇑ Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Northwest Normal University, Lanzhou, Gansu 730070, PR China Key Laboratory of Polymer Materials of Gansu Province, Northwest Normal University, Lanzhou, Gansu 730070, PR China College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, PR China
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
We synthesized a novel sensor was
never reported and explored the interaction of the sensor and Fe3+ by MS, XRD and IR. The fluorescence revealed that receptor S is an excellent sensor in the recognition to Fe3+ (very few reported) selectively. The test strips were containing S were fabricated, which also shows a highly sensitively to Fe3+.
a r t i c l e
i n f o
Article history: Received 3 August 2013 Received in revised form 29 October 2013 Accepted 3 November 2013 Available online 11 November 2013 Keywords: Phenazine Iron ion Fluorescence change Test kit
a b s t r a c t Two kinds of fluorescent sensors (S and S1) for Fe3+ bearing 1H-Imidazo [4,5-b] phenazine derivatives have been designed and synthesized. Between the two sensors, S showed excellent fluorescent specific selectivity and high sensitivity for Fe3+ in DMSO solution. The test strip based on S was fabricated, which could act as a convenient and efficient Fe3+ test kit. The recognition mechanism of the sensor toward Fe3+ was evaluated by MS, IR and XRD. The detection limit of the sensor S towards Fe3+ is 4.8 106 M. And other cations, including Hg2+,Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ had no influence on the probing behavior. Ó 2013 Elsevier B.V. All rights reserved.
Introduction Iron ion plays an important role in the physiology of human beings, such as cellular metabo-lism, energy generation, oxygen transport, gene expression, neurotransmission and regulation of metalloenzymes [1,2]. It is also found as the essential element in myoglobin, hemoglobin, cytochromes [3,4]. These functions are ⇑ Corresponding author at: Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Northwest Normal University, Lanzhou, Gansu 730070, PR China. Tel.: +86 931 7973120. E-mail address: [email protected] (T.-b. Wei). 1386-1425/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.saa.2013.11.004
dependent on the iron homeostasis in human body, thus both iron deficiency and iron overload are harmful to human health. Such as b-thalassemia, Friedreich’s ataxia, Alzheimer’s disease, Parkin-son’s disease and epilepsy [5,6]. Moreover, excessive of iron ion is also harmful to the environment [7]. Accordingly, the development of probes for iron ion has been a subject of intense research interest and a variety of sensing devices, involving calix[n]arenes, polythiacrown ethers, Schiff bases, and tripodal derivatives have been reported and used with some success in biological applications for the selective detection of iron ion [8–11]. Nevertheless, their preparations require laborious multistep organic synthesis, which renders their discovery processes
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slow and causes prohibitively high cost. Therefore, developing simple, new, and highly sensitive and selective sensors of iron ion remains a challenge. Currently, reactive probes have emerged as an important area. However, most of the organic reactions were required relatively strict conditions, which limited the probes application. Although a fluorescent probe has been developed by Nagano’s group [12], multifunctional probes are quite rare and still highly desirable. Phenazine derivatives have been synthesized and been used for organic electronics for a long time and they are ideal platforms for the development of anion, cation, and neutral molecule recognition, but they have seldom been used in host–guest chemistry. Moreover, among the different fluorogenic units, phenazine is very sensitive to conformational change. Phenazine-based fluorescent chemosensors are still very scarce, although in principle, well-designed ones should show very good performance [13–17]. In view of this requirement and as part of our research effort devoted to ion recognition [18–22], an attempt was made to obtain efficient fluorescent chemosensor which could sense iron ion with specific selectivity and high sensitivity in DMSO solution. Herein, we report the cation selective properties of a simple phenazine derivative (sensor S or S1) by the facile condensation reaction of 2-hydroxybenzaldehyde (sensor S) or benzaldehyde (sensor S1) with 2,3-diamino-phenazine (Scheme 1). The strategy employed in the design of this sensor is as follows. Firstly, we introduced nitrogen and oxygen heteroatoms as chelating sites. Secondly, a phenazine group was introduced as fluorophore to achieve recognitions. Ultimately, the sensor S and S1 was designed with ease of synthesis and low cost. We are very gratifying to see that the results go as we expected, sensor S shows fluorescent selectivity for Fe3+ in DMSO solution.
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2,3-Diamino-phenazine (0.42 g, 2.0 mmol), 2-hydroxyl-1-benzaldehyde (0.27 g, 2.2 mmol) and catalytic amount of acetic acid (AcOH) were combined in hot absolute DMF (20 mL) (Scheme 1). The solution was stirred under reflux conditions for 8 h, after cooling to room temperature, the brown precipitate was filtrated, washed with hot absolute ethanol three times, then recrystallized with DMF-H2O to get brown powdery product S. The other compound S1 was prepared by similar procedures. S: yield: 45%; m.p. > 300 °C; 1H NMR (DMSO-d6, 400 MHz) d 13.52 (s 1H, NH), d 12.91 (s 1H, OH), d 8.51 (d 1H ArH), 8.31– 8.32 (m 2H, ArH) 7.96–7.53 (m 4H, ArH) 7.51–7.13 (m 2H, ArH) 7.09 (m 1H, ArH). 13C NMR (DMSO-d6, 150 MHz) d 159.64, 159.17, 146.26, 140.28, 139.95, 138.68, 133.88, 129.02, 128.84, 127.96, 119.61, 117.54, 114.03, 111.90, 106.42. IR (KBr, cm1) v: 3310.70 (OAH), 3047.32 (NAH), 1661.20 (C@N), 1613.04 (Ar, C@C), 1528.76 (Ar, C@C), 1488.12 (Ar, C@C). ESI-MS m/z: (M+H)+ Calcd for C19H12N4O 313.3; Found 313.3; Anal. Calcd. for C19H12N4O: C 73.07, H 3.87, N 17.94; Found C 73.04, H 3.84, N 17.90. The same method is used for the synthesis of 2-phenyl-1H-imidazo[4,5-b] phenazine (S1). S1: yield: 80%; m.p. > 300 °C; 1H NMR (DMSO-d6, 400 MHz) d 13.44 (s 1H), d 8.51 (s 1H), 8.38–8.37 (d 2H), 8.26–8.23 (d 3H), 7.89–7.88 (d 2H), 7.67–7.66 (d 3H). 13C NMR (DMSO-d6, 150 MHz) d 159.55, 148.88, 141.87, 141.68, 140.51, 140.23, 139.84, 131.87, 131.88, 129.85, 129.55, 129.23, 129.22, 129.02, 128.80, 127.76, 127.75, 114.84, 105.91; IR (KBr, cm1) v: 3168 (NH), 1693 (C@N); ESI-MS m/z: (M + H)+ Calcd for C19H12N4 297.1; Found 297.2; Anal. Calcd. For C19H12N4: C, 77.01; H, 4.08; N, 18.91; Found C, 77.08; H, 4.04; N, 18.88. General procedure for fluorescence experiments
Experimental Materials and physical methods All reagents and solvents were commercially available at analytical grade and were used without further purification. 1H NMR spectra were recorded on a Mercury-400BB spectrometer at 400 MHz and 13C NMR spectra were recorded on a Mercury600BB spectrometer at 150 MHz. Chemical shifts are reported in ppm down field from tetramethylsilane (TMS, d scale with solvent resonances as internal standards). The fluorescence spectra were recorded with a Shimadzu RF-5301 spectrofluorimeter. Melting points were measured on an X-4 digital melting-point apparatus (uncorrected). Infrared spectra were performed on a Digilab FTS3000 FT-IR spectrophotometer. XRD analysis was measured at room temperature on a Japan Rigaku D/MAX-2400/PC diffractometer. Massspectra was recorded on an esquire6000 MS instrument equipped with an electrospray (ESI) ion source and version 3.4 of Bruker Daltonics Data Analysis as the data collection system. Synthesis of 2-(2-hydroxyphenyl)-1H-imidazo [4,5-b] phenazine (S) 2,3-Diamino-phenazine was prepared following the reported procedure [15,16].
All fluorescence spectra were recorded on a Shimadzu RF–5301 fluorescence spectrometer after the addition of perchlorate metal salts in DMSO, while keeping the ligand concentration constant (2.0 105 M). The excitation wavelength was 408 nm. Solutions of metal ions were prepared from the perchlorate salts of Fe3+, Hg2+, Ag+, Ca2+,Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+. General procedure for 1H NMR experiments For 1H NMR titrations, one stock solution was prepared in DMSO-d6 which containing the sensor only. Aliquots of the solution were mixed directly in NMR tubes. Results and discussion In order to investigate the Fe3+ recognition abilities of the sensors S and S1, we carried out a series of Host–Guest recognition experiments in DMSO solution. The recognition profiles of the chemosensor S toward various metal ions, Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+, were investigated by fluorescence spectroscopy in DMSO solution. As shown in Fig. 1, in the fluorescence spectrum, the emission of S appeared at the maximum emission wavelength was 533 nm in DMSO solution
Scheme 1. Synthetic procedures for sensor S and S1.
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Fig. 1. Fluorescence spectra of S (20 lM) upon an excitation at 408 nm in DMSO in the presence of Fe3+ (20 equiv.). Inset: photograph from left to right shows the change in the fluorescence of S, S + Fe3+ (20 equiv.) in DMSO.
Pb2+, Zn2+, Cr3+, and Mg2+) were added to the DMSO solutions of S1, no obvious changes were observed. In corresponding fluorescent spectrum of S1, there is no selectivity for the recognition of Fe3+, which indicated that S1 couldn’t sense selectively Fe3+ under these conditions. Therefore, according to these results we can find that the hydroxyl group acted as a functional group and played a crucial role in the process of colorimetric recognition. The sensor S employ hydroxyl group as functional group, which possess fluorescent response abilities for Fe3+. At the same time, because the S1 has no hydroxyl unit as functional group, it has no fluorescent capability to fluorescent recognize any cations. As S showed specific selectivity for Fe3+, a series of experiments was carried out to investigate the Fe3+ recognition capability and mechanism of S. An important feature of the sensor S is its high selectivity toward the analyte over other competitive species. The variations of fluorescent spectrum of sensor S in DMSO solution caused by the metal ions Hg2+, Ag+,Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ were recorded in Fig. 4. It is
when excited at kex = 408 nm. When 20 equivalents of Fe3+ was added to the DMSO solution of sensor S, after 60 min, dramatic fluorescent quenching was observed, the apparent fluorescence emission color change from yellow to colorless could be distinguished by naked-eyes through UV lamp. Suggesting that compound S shows a specific response to Fe3+. To validate the selectivity of sensor S, the same tests were also applied using Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ ions, and none of these cations induced any significant changes in the fluorescent spectrum of the sensor Fig. 2. Therefore, in DMSO solution, S showed specific fluorescent selectivity to Fe3+. The same tests were applied to S1 as shown in Fig. 3. In this case, when various cations (Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Fig. 3. Fluorescence emission data for S1 (20 lM) and different metal ions (20 equiv.): (1) only S1, (2) Fe3+, (3) Hg2+, (4) Ag+, (5) Ca2+, (6) Cu2+, (7) Co2+, (8) Ni2+, (9) Cd2+, (10) Pb2+, (11) Zn2+, (12) Cr3+ and (13) Mg2+; as their perchlorate salts, in DMSO solution. (excitation wavelength = 408 nm).
Fig. 2. (a) Fluorescence emission data for a 1:20 mixture of S (20 lM) and different metal ions: (1) only S, (2) Fe3+, (3)Hg2+, (4) Ag+, (5) Ca2+, (6) Cu2+, (7) Co2+, (8) Ni2+, (9) Cd2+, (10) Pb2+, (11) Zn2+, (12) Cr3+ and (13) Mg2+; as their perchlorate salts, in DMSO solution. (excitation wavelength = 408 nm). (b) Visual fluorescence emissions of sensor S after the addition of Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+ and Mg2+ (20 equiv.) in DMSO on excitation at 408 nm using UV lamp at room temperature.
Fig. 4. Fluorescence intensity changes of the S (20 lM) to Fe3+ (20 equiv.) in the presence of various test cations in DMSO solution. (a) only S, (b) S + Fe3+, (c) S + Hg2+, (d) S + Hg2++Fe3+, (e) S + Ag2+, (f) S + Ag2++Fe3+, (g) S + Ca2+, (h) S + Ca2++Fe3+, (i) S + Cu2+, (j) S + Cu2++Fe3+, (k) S + Co2+, (l) S + Co2++Fe3+, (m) S + Ni2+, (n) S + Ni2++Fe3+, (o) S + Cd2+, (p) S + Cd2++Fe3+, (q) S + Pb2+, (r) S + Pb2++Fe3+, (s) S + Zn2+, (t) S + Zn2++Fe3+, (u) S + Cr3+, (v) S + Cr3++Fe3+, (w) S + Mg2+, (x) S + Mg2++Fe3+.
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noticeable that the miscellaneous competitive metal ions did not lead to any significant interference. In the presence of these cations, the Fe3+ still produced similar emission changes. These results shown that the selectivity of sensor S toward Fe3+ was no influence by the presence of other cations and suggested that it could be used as a fluorescent chemosensor for Fe3+ in DMSO solution. In addition, the changes in the Fluorescence intensity depending on the reaction time were recorded from 0 to 85 min, for a 1:20 mixture of S (2.0 105 M) and Fe(ClO4)3 in DMSO at room temperature (Fig. 5) [23]. It clearly shows that the reaction completed within 60 min after addition of Fe3+. To further evaluate the Fe3+-responsive nature of S, fluorescence titration with Fe3+ in varying concentrations was conducted. As shown in Fig. 6, the addition of increasing concentrations of Fe3+, the emission peak at 533 nm gradually diminished intensity, and the fluorescence of S was essentially quenched by 3.4 equiv. of Fe3+ ion. The data were recorded 60 min after Fe3+ was added. The fluorescence quantum yield (U) of sensor S in DMSO is 0.48, whereas it drops 0.03 when sensor S reacts with Fe3+. The binding constant Ka of the metal complex was determined as 3.91 105 M1. And the detection limit of the S for the determination of Fe3+ was estimated to be 4.8 106 M, Simultaneously, the molar extinction coefficients of the probe is 3.11 104 M1 cm1
Fig. 6. (a) Fluorescence spectra of S (20 lM) in the presence of different concentration of Fe3+ (0–3.4 equiv.) in DMSO. (b) A plot of fluorescence intensity depending on the concentration of Fe3+ in the range from 0 to 3.4 equivalents.
Fig. 5. Time-dependent of S (2.0 105 M) upon addition of Fe3+ (1.0 103 M) in DMSO. (a) Fluorescence intensity changes: each spectrum was recorded after 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80 and 85 min. (b) A plot of Fluorescence intensity that is estimated as the peak height at 533 nm.
and the complex with Fe3+ is 6.78 104 M1 cm1 [24], which pointing to the high detection sensitivity. With such a high selectivity and sensitivity, S could serve as a fluorescent ON–OFF sensor for Fe3+ (see Supporting Information). In good agreement with this finding, the product S, S1 and S with Fe3+ was subjected to mass spectral analyses. The ion peaks were detected at m/z 313.3 (Fig. S1) and 297.2 (Fig. S2), which are corresponding to [S + H]+ and [S1 + H]+. The ion peak at m/z 678.3 demonstrated the presence of [2S + Fe3+] (Fig. S3). The presence of Fe3+ leads to the formation of 2S + Fe3+, which is then converted to a structural change, the phenol OAH of S appeared tautomerism to C@O [25] (Scheme 2), producing the MS signals at m/z 678.3 showing the formation of a 2:1 bonding mode between S and Fe3+ ion. Corresponding, the X-ray diffraction (XRD) of S were determined. We obtained a d-spacing of 3.87 Å by 2h = 22.1°, it suggested that it was p–p stacking between aromatic nucleus [26] (Fig. 7). 1 H NMR (Figs. S4 and S5) and 13C NMR (Figs. S6 and S7) spectra were further confirmed that the structure of S and S1. The recognition mechanism of the sensor S with Fe3+ were investigated by IR spectra. In the IR spectra of S, the stretching vibration absorption peaks of imidazole NAH, imidazole C@N and phenol OAH appeared at 3047, 1661 and 3310 cm1 respectively. However, when S coordinated with Fe3+, the stretching vibration absorption peaks
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Scheme 2. The proposed structures of S for Fe3+ ion.
Fig. 9. Photographs of S on test papers. left: only S, right: after immersion into DMSO solution with Fe3+ under irradiation at 365 nm. Fig. 7. XRD diagram of S.
of imidazole NAH and imidazole C@N shifted to 2957 and 1619 cm1, while, the phenol OAH appeared tautomerism to C@O, the stretching vibration absorption peaks shifted to 1744 cm1, which indicated that S complexed with Fe3+ via O– Fe3+ –N coordination bond as shown in Fig. 8. The conclusion is further evidence the mass spectrometry. To investigate the practical application of chemosensor S, test strips were prepared by immersing filter papers into a DMSO solution of S (2 104 mol/L) and then drying in air. The test strips containing S was utilized to sense Fe3+. As shown in Fig. 9, when Fe3+ were added on the test kits, the obvious color change was
observed under the 365 nm UV lamp. Therefore, the test strips could conveniently detect Fe3+ in solutions. The recognition profiles of sensor S toward various metal cations, Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ were also investigated by UV–vis spectroscopy in DMSO. As shown in Fig. S8, no obvious changes were observed. In corresponding UV–vis spectrum of S, there is no selectivity for the recognition of any cations. Therefore, the receptor S only displayed dramatic quenched fluorescence intensity selectively for Fe3+ over other ions investigated in DMSO solution. Conclusions We have constructed a fluorescent sensor 1H-imidazo[4,5-b] Phenazine derivatives S or S1 for recognition of ions. The sensor S displayed high selectivity and sensitivity for iron ion in DMSO solution, which served as an ON–OFF type sensor. The recognition mechanism of the sensor S toward Fe3+ was evaluated by MS, IR and XRD. The presence of Fe3+ leads to the formation of 2S + Fe3+, which is then converted to a structural change, the phenol OAH of S appeared tautomerism to C@O, and the fluorescence quenching. Consequently, the product S was an splendid indicator over other common cations including Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ in the same media without interference. In addition, test strips were prepared by immersing filter papers (3 1 cm2) into the DMSO solution of S which exhibits a good selectivity to Fe3+. Therefore, the sensor S has potential applications in physiological and environmental systems for Fe3+ detection. Acknowledgments
Fig. 8. IR spectra of compound S and S + Fe3+ complex in KBr disks.
This work was supported by the National Natural Science Foundation of China (No. 21064006, 21262032 and 21161018),
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the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (No. IRT1177), the Natural Science Foundation of Gansu Province (No. 1010RJZA018), the Youth Foundation of Gansu Province (No. 2011GS04735) and NWNU-LKQN-11-32. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.saa.2013.11.004. References [1] M.W. Hentze, M.U. Muckenthaler, B. Galy, C. Camaschella, Two to tango: regulation of mammalian iron metabolism, Cell 142 (2010) 24–28. [2] W.H. Chen, Y. Xing, Y. Pang, A highly selective pyrophosphate sensor based on ESIPT turn-on in water, Org. Lett. 13 (2011) 1362–1365. [3] A.S. Zhang, C.A. Enns, Molecular basis of cell and developmental biology, J. Biol. Chem. 283 (2008) 17494–17502. [4] R. Evstatiev, C. Gasche, Iron sensing and signalling, Gut 61 (2012) 933–952. [5] G. Papanikolaou, K. Papanikolaou, Iron metabolism and toxicity, Toxicol. Appl. Pharmacol. 202 (2005) 199–211. [6] D.S. Kalinowski, D.R. Richardson, The evolution of iron chelators for the treatment of iron overload disease and cancer, Pharmacol. Rev. 579 (2005) 547–553. [7] Z.X. Li, L.F. Zhang, X.Y. Li, Y.K. Guo, Z.H. Ni, J.H. Chen, L.H. Wei, M.M. Yu, A fluorescent color/intensity changed chemosensor for Fe3+ by photo-induced electron transfer (PET) inhibition of fluoranthene derivative, Dyes Pigments 94 (2012) 60–65. [8] M. Yang, M.T. Sun, Z.P. Zhang, S.H. Wang, A novel dansyl-based fluorescent probe for highly selective detection of ferric ions, Talanta 105 (2013) 34–39. [9] M.J.C. Marenco, C. Fowley, B.W. Hyland, G.R.C. Hamilton, G.R. Dolores, F.C. John, A new use for an old molecule: N-phenyl-2-(2-hydroxynaphthalen – 1ylmethylene) hydrazinecarbothioamide as a ratiometric‘‘Off-On’’ fluorescent probe for iron, Tetrahedron Lett. 53 (2012) 670–673. [10] M.Y. Xu, S.Z. Wu, F. Zeng, C.M. Yu, Cyclodextrin supramolecular complex as a water-soluble ratiometric sensor for ferric ion sensing, Langmuir 26 (2010) 4529–4533. [11] Q.Y. Zhou, W.Z. Liu, L. Chang, F. Chen, Spectral study of the interaction between 2-pyridinecarbaldehyde-p-phenyldihydrazone and ferric iron and its analytical application, Spectrochim. Acta A 92 (2012) 78–83.
519
[12] B. Vandana, G. Ankush, M. Kumar, Fe3+-ensemble of triazole appended pentacenequinone derivative for ‘‘turn-on’’ detection of fluoride ions, Talanta 105 (2013) 152–157. [13] K. Sasakura, K. Hanaoka, N. Shibuya, Y. Mikami, Y. Kimura, T. Komatsu, T. Ueno, T. Terai, H. Kimura, T. Nagano, Development of a highly selective fluorescence probe for hydrogen sulfide, J Am. Chem. Soc. 133 (2011) 18003–18005. [14] G. Li, Y.C. Wu, J.K. Gao, C.Y. Wang, J.B. Li, H.C. Zhang, Synthesis and physical properties of four hexazapentacene derivatives, J Am. Chem. Soc. 134 (2012) 20298–20301. [15] A.B. Korzhenevskii, L.V. Markova, S.V. Efimova, O.I. Koifman, E.V. Krylova, Metal complexes of a hexameric network tetrapyrazinoporpyrazine: I. synthesis and identification, Russ. J. Gen. Chem. 75 (2005) 980–984. [16] A.M. Amer1, A.A. Bahnasawi1, M.R.H. Mahran, M. Lapib, On the synthesis of pyrazino[2,3-b]phenazine and 1H-imidazo[4,5-b]phenazine derivatives, Monatshefte fÜr Chemie 130 (1999) 1217–1225. [17] A.A.E. Bahnasawy, M.F.E. Ahwany, Synthesis of some pyridoimidazophenazine derivatives, Phosphorus Sulfur 8 (2007) 1937–1944. [18] J.Q. Li, T.B. Wei, Q. Lin, P. Li, Y.M. Zhang, Mercapto thiadiazole based sensor with colorimetric specific selectivity for AcO in aqueous solution, Spectrochim. Acta A 83 (2011) 187–193. [19] P. Li, Y.M. Zhang, Q. Lin, J.Q. Li, T.B. Wei, A novel colorimetric HSO4 sensor in aqueous media, Spectrochim. Acta A 80 (2012) 152–157. [20] T.B. Wei, P. Zhang, B.B. Shi, P. Chen, Q. Lin, J. Liu, Y.M. Zhang, A highly selective chemosen sor for colorimet ric detection of Fe3+ and fluorescence turn-on response of Zn2+, Dyes Pigments 97 (2013) 297–302. [21] Q. Lin, P. Chen, J. Liu, Y.P. Fu, Y.M. Zhang, T.B. Wei, Colorimetric chemosensor and test kit for detection copper(II) cations in aqueous solution with specific selectivity and high sensitivity, Dyes Pigments 98 (2013) 100–105. [22] Y.M. Zhang, B.B. Shi, P. Zhang, P. Chen, Q. Lin, T.B. Wei, A highly selective dualchannel Hg2+ chemosensor based on an easy to prepare double naphthalene Schiff base, Sci. China Chem. 56 (2013) 612–618. [23] M. Santra, K.H. Ahn, A ‘‘ reactive ’’ ratiometric fluorescent probe for mercury species, Org. Lett. 13 (2011) 3422–3425. [24] P. Wang, C. Klein, R.H. Baker, S.M. Zakeeruddin, M.G. tzel, A high molar extinction coefficient sensitizer for stable dye-sensitized solar cells, J. Am. Chem. Soc. 127 (2005) 808–809. [25] K. Benelhadj, J. Massue, P. Retailleau, G. Ulrich, R. Ziessel, 2-(20 Hydroxyphenyl) benzimidazole and 9,10-phenanthroimidazole chelates and borate complexes: solution-and solid-state emitters, Org. Lett. 15 (2013) 2918–2921. [26] T. Tao, W. Assenmacher, H. Peterlik, G. Schnakenburg, K. Heinz, Dötz, pyridinebridged benzimidazolium salts: synthesis, aggregation, and application as phase-transfer catalysts, Angew. Chem. Int. Ed. 47 (2008) 7127–7131.
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa
A highly selective fluorescent chemosensor for iron ion based on 1H-imidazo [4,5-b] phenazine derivative Guo-ying Gao, Wen-juan Qu, Bing-bing Shi, Peng Zhang, Qi Lin, Hong Yao, Wen-long Yang, You-ming Zhang, Tai-bao Wei ⇑ Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Northwest Normal University, Lanzhou, Gansu 730070, PR China Key Laboratory of Polymer Materials of Gansu Province, Northwest Normal University, Lanzhou, Gansu 730070, PR China College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, Gansu 730070, PR China
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
We synthesized a novel sensor was
never reported and explored the interaction of the sensor and Fe3+ by MS, XRD and IR. The fluorescence revealed that receptor S is an excellent sensor in the recognition to Fe3+ (very few reported) selectively. The test strips were containing S were fabricated, which also shows a highly sensitively to Fe3+.
a r t i c l e
i n f o
Article history: Received 3 August 2013 Received in revised form 29 October 2013 Accepted 3 November 2013 Available online 11 November 2013 Keywords: Phenazine Iron ion Fluorescence change Test kit
a b s t r a c t Two kinds of fluorescent sensors (S and S1) for Fe3+ bearing 1H-Imidazo [4,5-b] phenazine derivatives have been designed and synthesized. Between the two sensors, S showed excellent fluorescent specific selectivity and high sensitivity for Fe3+ in DMSO solution. The test strip based on S was fabricated, which could act as a convenient and efficient Fe3+ test kit. The recognition mechanism of the sensor toward Fe3+ was evaluated by MS, IR and XRD. The detection limit of the sensor S towards Fe3+ is 4.8 106 M. And other cations, including Hg2+,Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ had no influence on the probing behavior. Ó 2013 Elsevier B.V. All rights reserved.
Introduction Iron ion plays an important role in the physiology of human beings, such as cellular metabo-lism, energy generation, oxygen transport, gene expression, neurotransmission and regulation of metalloenzymes [1,2]. It is also found as the essential element in myoglobin, hemoglobin, cytochromes [3,4]. These functions are ⇑ Corresponding author at: Key Laboratory of Eco-Environment-Related Polymer Materials, Ministry of Education of China, Northwest Normal University, Lanzhou, Gansu 730070, PR China. Tel.: +86 931 7973120. E-mail address: [email protected] (T.-b. Wei). 1386-1425/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.saa.2013.11.004
dependent on the iron homeostasis in human body, thus both iron deficiency and iron overload are harmful to human health. Such as b-thalassemia, Friedreich’s ataxia, Alzheimer’s disease, Parkin-son’s disease and epilepsy [5,6]. Moreover, excessive of iron ion is also harmful to the environment [7]. Accordingly, the development of probes for iron ion has been a subject of intense research interest and a variety of sensing devices, involving calix[n]arenes, polythiacrown ethers, Schiff bases, and tripodal derivatives have been reported and used with some success in biological applications for the selective detection of iron ion [8–11]. Nevertheless, their preparations require laborious multistep organic synthesis, which renders their discovery processes
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slow and causes prohibitively high cost. Therefore, developing simple, new, and highly sensitive and selective sensors of iron ion remains a challenge. Currently, reactive probes have emerged as an important area. However, most of the organic reactions were required relatively strict conditions, which limited the probes application. Although a fluorescent probe has been developed by Nagano’s group [12], multifunctional probes are quite rare and still highly desirable. Phenazine derivatives have been synthesized and been used for organic electronics for a long time and they are ideal platforms for the development of anion, cation, and neutral molecule recognition, but they have seldom been used in host–guest chemistry. Moreover, among the different fluorogenic units, phenazine is very sensitive to conformational change. Phenazine-based fluorescent chemosensors are still very scarce, although in principle, well-designed ones should show very good performance [13–17]. In view of this requirement and as part of our research effort devoted to ion recognition [18–22], an attempt was made to obtain efficient fluorescent chemosensor which could sense iron ion with specific selectivity and high sensitivity in DMSO solution. Herein, we report the cation selective properties of a simple phenazine derivative (sensor S or S1) by the facile condensation reaction of 2-hydroxybenzaldehyde (sensor S) or benzaldehyde (sensor S1) with 2,3-diamino-phenazine (Scheme 1). The strategy employed in the design of this sensor is as follows. Firstly, we introduced nitrogen and oxygen heteroatoms as chelating sites. Secondly, a phenazine group was introduced as fluorophore to achieve recognitions. Ultimately, the sensor S and S1 was designed with ease of synthesis and low cost. We are very gratifying to see that the results go as we expected, sensor S shows fluorescent selectivity for Fe3+ in DMSO solution.
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2,3-Diamino-phenazine (0.42 g, 2.0 mmol), 2-hydroxyl-1-benzaldehyde (0.27 g, 2.2 mmol) and catalytic amount of acetic acid (AcOH) were combined in hot absolute DMF (20 mL) (Scheme 1). The solution was stirred under reflux conditions for 8 h, after cooling to room temperature, the brown precipitate was filtrated, washed with hot absolute ethanol three times, then recrystallized with DMF-H2O to get brown powdery product S. The other compound S1 was prepared by similar procedures. S: yield: 45%; m.p. > 300 °C; 1H NMR (DMSO-d6, 400 MHz) d 13.52 (s 1H, NH), d 12.91 (s 1H, OH), d 8.51 (d 1H ArH), 8.31– 8.32 (m 2H, ArH) 7.96–7.53 (m 4H, ArH) 7.51–7.13 (m 2H, ArH) 7.09 (m 1H, ArH). 13C NMR (DMSO-d6, 150 MHz) d 159.64, 159.17, 146.26, 140.28, 139.95, 138.68, 133.88, 129.02, 128.84, 127.96, 119.61, 117.54, 114.03, 111.90, 106.42. IR (KBr, cm1) v: 3310.70 (OAH), 3047.32 (NAH), 1661.20 (C@N), 1613.04 (Ar, C@C), 1528.76 (Ar, C@C), 1488.12 (Ar, C@C). ESI-MS m/z: (M+H)+ Calcd for C19H12N4O 313.3; Found 313.3; Anal. Calcd. for C19H12N4O: C 73.07, H 3.87, N 17.94; Found C 73.04, H 3.84, N 17.90. The same method is used for the synthesis of 2-phenyl-1H-imidazo[4,5-b] phenazine (S1). S1: yield: 80%; m.p. > 300 °C; 1H NMR (DMSO-d6, 400 MHz) d 13.44 (s 1H), d 8.51 (s 1H), 8.38–8.37 (d 2H), 8.26–8.23 (d 3H), 7.89–7.88 (d 2H), 7.67–7.66 (d 3H). 13C NMR (DMSO-d6, 150 MHz) d 159.55, 148.88, 141.87, 141.68, 140.51, 140.23, 139.84, 131.87, 131.88, 129.85, 129.55, 129.23, 129.22, 129.02, 128.80, 127.76, 127.75, 114.84, 105.91; IR (KBr, cm1) v: 3168 (NH), 1693 (C@N); ESI-MS m/z: (M + H)+ Calcd for C19H12N4 297.1; Found 297.2; Anal. Calcd. For C19H12N4: C, 77.01; H, 4.08; N, 18.91; Found C, 77.08; H, 4.04; N, 18.88. General procedure for fluorescence experiments
Experimental Materials and physical methods All reagents and solvents were commercially available at analytical grade and were used without further purification. 1H NMR spectra were recorded on a Mercury-400BB spectrometer at 400 MHz and 13C NMR spectra were recorded on a Mercury600BB spectrometer at 150 MHz. Chemical shifts are reported in ppm down field from tetramethylsilane (TMS, d scale with solvent resonances as internal standards). The fluorescence spectra were recorded with a Shimadzu RF-5301 spectrofluorimeter. Melting points were measured on an X-4 digital melting-point apparatus (uncorrected). Infrared spectra were performed on a Digilab FTS3000 FT-IR spectrophotometer. XRD analysis was measured at room temperature on a Japan Rigaku D/MAX-2400/PC diffractometer. Massspectra was recorded on an esquire6000 MS instrument equipped with an electrospray (ESI) ion source and version 3.4 of Bruker Daltonics Data Analysis as the data collection system. Synthesis of 2-(2-hydroxyphenyl)-1H-imidazo [4,5-b] phenazine (S) 2,3-Diamino-phenazine was prepared following the reported procedure [15,16].
All fluorescence spectra were recorded on a Shimadzu RF–5301 fluorescence spectrometer after the addition of perchlorate metal salts in DMSO, while keeping the ligand concentration constant (2.0 105 M). The excitation wavelength was 408 nm. Solutions of metal ions were prepared from the perchlorate salts of Fe3+, Hg2+, Ag+, Ca2+,Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+. General procedure for 1H NMR experiments For 1H NMR titrations, one stock solution was prepared in DMSO-d6 which containing the sensor only. Aliquots of the solution were mixed directly in NMR tubes. Results and discussion In order to investigate the Fe3+ recognition abilities of the sensors S and S1, we carried out a series of Host–Guest recognition experiments in DMSO solution. The recognition profiles of the chemosensor S toward various metal ions, Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+, were investigated by fluorescence spectroscopy in DMSO solution. As shown in Fig. 1, in the fluorescence spectrum, the emission of S appeared at the maximum emission wavelength was 533 nm in DMSO solution
Scheme 1. Synthetic procedures for sensor S and S1.
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Fig. 1. Fluorescence spectra of S (20 lM) upon an excitation at 408 nm in DMSO in the presence of Fe3+ (20 equiv.). Inset: photograph from left to right shows the change in the fluorescence of S, S + Fe3+ (20 equiv.) in DMSO.
Pb2+, Zn2+, Cr3+, and Mg2+) were added to the DMSO solutions of S1, no obvious changes were observed. In corresponding fluorescent spectrum of S1, there is no selectivity for the recognition of Fe3+, which indicated that S1 couldn’t sense selectively Fe3+ under these conditions. Therefore, according to these results we can find that the hydroxyl group acted as a functional group and played a crucial role in the process of colorimetric recognition. The sensor S employ hydroxyl group as functional group, which possess fluorescent response abilities for Fe3+. At the same time, because the S1 has no hydroxyl unit as functional group, it has no fluorescent capability to fluorescent recognize any cations. As S showed specific selectivity for Fe3+, a series of experiments was carried out to investigate the Fe3+ recognition capability and mechanism of S. An important feature of the sensor S is its high selectivity toward the analyte over other competitive species. The variations of fluorescent spectrum of sensor S in DMSO solution caused by the metal ions Hg2+, Ag+,Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ were recorded in Fig. 4. It is
when excited at kex = 408 nm. When 20 equivalents of Fe3+ was added to the DMSO solution of sensor S, after 60 min, dramatic fluorescent quenching was observed, the apparent fluorescence emission color change from yellow to colorless could be distinguished by naked-eyes through UV lamp. Suggesting that compound S shows a specific response to Fe3+. To validate the selectivity of sensor S, the same tests were also applied using Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ ions, and none of these cations induced any significant changes in the fluorescent spectrum of the sensor Fig. 2. Therefore, in DMSO solution, S showed specific fluorescent selectivity to Fe3+. The same tests were applied to S1 as shown in Fig. 3. In this case, when various cations (Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Fig. 3. Fluorescence emission data for S1 (20 lM) and different metal ions (20 equiv.): (1) only S1, (2) Fe3+, (3) Hg2+, (4) Ag+, (5) Ca2+, (6) Cu2+, (7) Co2+, (8) Ni2+, (9) Cd2+, (10) Pb2+, (11) Zn2+, (12) Cr3+ and (13) Mg2+; as their perchlorate salts, in DMSO solution. (excitation wavelength = 408 nm).
Fig. 2. (a) Fluorescence emission data for a 1:20 mixture of S (20 lM) and different metal ions: (1) only S, (2) Fe3+, (3)Hg2+, (4) Ag+, (5) Ca2+, (6) Cu2+, (7) Co2+, (8) Ni2+, (9) Cd2+, (10) Pb2+, (11) Zn2+, (12) Cr3+ and (13) Mg2+; as their perchlorate salts, in DMSO solution. (excitation wavelength = 408 nm). (b) Visual fluorescence emissions of sensor S after the addition of Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+ and Mg2+ (20 equiv.) in DMSO on excitation at 408 nm using UV lamp at room temperature.
Fig. 4. Fluorescence intensity changes of the S (20 lM) to Fe3+ (20 equiv.) in the presence of various test cations in DMSO solution. (a) only S, (b) S + Fe3+, (c) S + Hg2+, (d) S + Hg2++Fe3+, (e) S + Ag2+, (f) S + Ag2++Fe3+, (g) S + Ca2+, (h) S + Ca2++Fe3+, (i) S + Cu2+, (j) S + Cu2++Fe3+, (k) S + Co2+, (l) S + Co2++Fe3+, (m) S + Ni2+, (n) S + Ni2++Fe3+, (o) S + Cd2+, (p) S + Cd2++Fe3+, (q) S + Pb2+, (r) S + Pb2++Fe3+, (s) S + Zn2+, (t) S + Zn2++Fe3+, (u) S + Cr3+, (v) S + Cr3++Fe3+, (w) S + Mg2+, (x) S + Mg2++Fe3+.
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noticeable that the miscellaneous competitive metal ions did not lead to any significant interference. In the presence of these cations, the Fe3+ still produced similar emission changes. These results shown that the selectivity of sensor S toward Fe3+ was no influence by the presence of other cations and suggested that it could be used as a fluorescent chemosensor for Fe3+ in DMSO solution. In addition, the changes in the Fluorescence intensity depending on the reaction time were recorded from 0 to 85 min, for a 1:20 mixture of S (2.0 105 M) and Fe(ClO4)3 in DMSO at room temperature (Fig. 5) [23]. It clearly shows that the reaction completed within 60 min after addition of Fe3+. To further evaluate the Fe3+-responsive nature of S, fluorescence titration with Fe3+ in varying concentrations was conducted. As shown in Fig. 6, the addition of increasing concentrations of Fe3+, the emission peak at 533 nm gradually diminished intensity, and the fluorescence of S was essentially quenched by 3.4 equiv. of Fe3+ ion. The data were recorded 60 min after Fe3+ was added. The fluorescence quantum yield (U) of sensor S in DMSO is 0.48, whereas it drops 0.03 when sensor S reacts with Fe3+. The binding constant Ka of the metal complex was determined as 3.91 105 M1. And the detection limit of the S for the determination of Fe3+ was estimated to be 4.8 106 M, Simultaneously, the molar extinction coefficients of the probe is 3.11 104 M1 cm1
Fig. 6. (a) Fluorescence spectra of S (20 lM) in the presence of different concentration of Fe3+ (0–3.4 equiv.) in DMSO. (b) A plot of fluorescence intensity depending on the concentration of Fe3+ in the range from 0 to 3.4 equivalents.
Fig. 5. Time-dependent of S (2.0 105 M) upon addition of Fe3+ (1.0 103 M) in DMSO. (a) Fluorescence intensity changes: each spectrum was recorded after 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80 and 85 min. (b) A plot of Fluorescence intensity that is estimated as the peak height at 533 nm.
and the complex with Fe3+ is 6.78 104 M1 cm1 [24], which pointing to the high detection sensitivity. With such a high selectivity and sensitivity, S could serve as a fluorescent ON–OFF sensor for Fe3+ (see Supporting Information). In good agreement with this finding, the product S, S1 and S with Fe3+ was subjected to mass spectral analyses. The ion peaks were detected at m/z 313.3 (Fig. S1) and 297.2 (Fig. S2), which are corresponding to [S + H]+ and [S1 + H]+. The ion peak at m/z 678.3 demonstrated the presence of [2S + Fe3+] (Fig. S3). The presence of Fe3+ leads to the formation of 2S + Fe3+, which is then converted to a structural change, the phenol OAH of S appeared tautomerism to C@O [25] (Scheme 2), producing the MS signals at m/z 678.3 showing the formation of a 2:1 bonding mode between S and Fe3+ ion. Corresponding, the X-ray diffraction (XRD) of S were determined. We obtained a d-spacing of 3.87 Å by 2h = 22.1°, it suggested that it was p–p stacking between aromatic nucleus [26] (Fig. 7). 1 H NMR (Figs. S4 and S5) and 13C NMR (Figs. S6 and S7) spectra were further confirmed that the structure of S and S1. The recognition mechanism of the sensor S with Fe3+ were investigated by IR spectra. In the IR spectra of S, the stretching vibration absorption peaks of imidazole NAH, imidazole C@N and phenol OAH appeared at 3047, 1661 and 3310 cm1 respectively. However, when S coordinated with Fe3+, the stretching vibration absorption peaks
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Scheme 2. The proposed structures of S for Fe3+ ion.
Fig. 9. Photographs of S on test papers. left: only S, right: after immersion into DMSO solution with Fe3+ under irradiation at 365 nm. Fig. 7. XRD diagram of S.
of imidazole NAH and imidazole C@N shifted to 2957 and 1619 cm1, while, the phenol OAH appeared tautomerism to C@O, the stretching vibration absorption peaks shifted to 1744 cm1, which indicated that S complexed with Fe3+ via O– Fe3+ –N coordination bond as shown in Fig. 8. The conclusion is further evidence the mass spectrometry. To investigate the practical application of chemosensor S, test strips were prepared by immersing filter papers into a DMSO solution of S (2 104 mol/L) and then drying in air. The test strips containing S was utilized to sense Fe3+. As shown in Fig. 9, when Fe3+ were added on the test kits, the obvious color change was
observed under the 365 nm UV lamp. Therefore, the test strips could conveniently detect Fe3+ in solutions. The recognition profiles of sensor S toward various metal cations, Fe3+, Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ were also investigated by UV–vis spectroscopy in DMSO. As shown in Fig. S8, no obvious changes were observed. In corresponding UV–vis spectrum of S, there is no selectivity for the recognition of any cations. Therefore, the receptor S only displayed dramatic quenched fluorescence intensity selectively for Fe3+ over other ions investigated in DMSO solution. Conclusions We have constructed a fluorescent sensor 1H-imidazo[4,5-b] Phenazine derivatives S or S1 for recognition of ions. The sensor S displayed high selectivity and sensitivity for iron ion in DMSO solution, which served as an ON–OFF type sensor. The recognition mechanism of the sensor S toward Fe3+ was evaluated by MS, IR and XRD. The presence of Fe3+ leads to the formation of 2S + Fe3+, which is then converted to a structural change, the phenol OAH of S appeared tautomerism to C@O, and the fluorescence quenching. Consequently, the product S was an splendid indicator over other common cations including Hg2+, Ag+, Ca2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, Zn2+, Cr3+, and Mg2+ in the same media without interference. In addition, test strips were prepared by immersing filter papers (3 1 cm2) into the DMSO solution of S which exhibits a good selectivity to Fe3+. Therefore, the sensor S has potential applications in physiological and environmental systems for Fe3+ detection. Acknowledgments
Fig. 8. IR spectra of compound S and S + Fe3+ complex in KBr disks.
This work was supported by the National Natural Science Foundation of China (No. 21064006, 21262032 and 21161018),
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the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (No. IRT1177), the Natural Science Foundation of Gansu Province (No. 1010RJZA018), the Youth Foundation of Gansu Province (No. 2011GS04735) and NWNU-LKQN-11-32. Appendix A. Supplementary material Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.saa.2013.11.004. References [1] M.W. Hentze, M.U. Muckenthaler, B. Galy, C. Camaschella, Two to tango: regulation of mammalian iron metabolism, Cell 142 (2010) 24–28. [2] W.H. Chen, Y. Xing, Y. Pang, A highly selective pyrophosphate sensor based on ESIPT turn-on in water, Org. Lett. 13 (2011) 1362–1365. [3] A.S. Zhang, C.A. Enns, Molecular basis of cell and developmental biology, J. Biol. Chem. 283 (2008) 17494–17502. [4] R. Evstatiev, C. Gasche, Iron sensing and signalling, Gut 61 (2012) 933–952. [5] G. Papanikolaou, K. Papanikolaou, Iron metabolism and toxicity, Toxicol. Appl. Pharmacol. 202 (2005) 199–211. [6] D.S. Kalinowski, D.R. Richardson, The evolution of iron chelators for the treatment of iron overload disease and cancer, Pharmacol. Rev. 579 (2005) 547–553. [7] Z.X. Li, L.F. Zhang, X.Y. Li, Y.K. Guo, Z.H. Ni, J.H. Chen, L.H. Wei, M.M. Yu, A fluorescent color/intensity changed chemosensor for Fe3+ by photo-induced electron transfer (PET) inhibition of fluoranthene derivative, Dyes Pigments 94 (2012) 60–65. [8] M. Yang, M.T. Sun, Z.P. Zhang, S.H. Wang, A novel dansyl-based fluorescent probe for highly selective detection of ferric ions, Talanta 105 (2013) 34–39. [9] M.J.C. Marenco, C. Fowley, B.W. Hyland, G.R.C. Hamilton, G.R. Dolores, F.C. John, A new use for an old molecule: N-phenyl-2-(2-hydroxynaphthalen – 1ylmethylene) hydrazinecarbothioamide as a ratiometric‘‘Off-On’’ fluorescent probe for iron, Tetrahedron Lett. 53 (2012) 670–673. [10] M.Y. Xu, S.Z. Wu, F. Zeng, C.M. Yu, Cyclodextrin supramolecular complex as a water-soluble ratiometric sensor for ferric ion sensing, Langmuir 26 (2010) 4529–4533. [11] Q.Y. Zhou, W.Z. Liu, L. Chang, F. Chen, Spectral study of the interaction between 2-pyridinecarbaldehyde-p-phenyldihydrazone and ferric iron and its analytical application, Spectrochim. Acta A 92 (2012) 78–83.
519
[12] B. Vandana, G. Ankush, M. Kumar, Fe3+-ensemble of triazole appended pentacenequinone derivative for ‘‘turn-on’’ detection of fluoride ions, Talanta 105 (2013) 152–157. [13] K. Sasakura, K. Hanaoka, N. Shibuya, Y. Mikami, Y. Kimura, T. Komatsu, T. Ueno, T. Terai, H. Kimura, T. Nagano, Development of a highly selective fluorescence probe for hydrogen sulfide, J Am. Chem. Soc. 133 (2011) 18003–18005. [14] G. Li, Y.C. Wu, J.K. Gao, C.Y. Wang, J.B. Li, H.C. Zhang, Synthesis and physical properties of four hexazapentacene derivatives, J Am. Chem. Soc. 134 (2012) 20298–20301. [15] A.B. Korzhenevskii, L.V. Markova, S.V. Efimova, O.I. Koifman, E.V. Krylova, Metal complexes of a hexameric network tetrapyrazinoporpyrazine: I. synthesis and identification, Russ. J. Gen. Chem. 75 (2005) 980–984. [16] A.M. Amer1, A.A. Bahnasawi1, M.R.H. Mahran, M. Lapib, On the synthesis of pyrazino[2,3-b]phenazine and 1H-imidazo[4,5-b]phenazine derivatives, Monatshefte fÜr Chemie 130 (1999) 1217–1225. [17] A.A.E. Bahnasawy, M.F.E. Ahwany, Synthesis of some pyridoimidazophenazine derivatives, Phosphorus Sulfur 8 (2007) 1937–1944. [18] J.Q. Li, T.B. Wei, Q. Lin, P. Li, Y.M. Zhang, Mercapto thiadiazole based sensor with colorimetric specific selectivity for AcO in aqueous solution, Spectrochim. Acta A 83 (2011) 187–193. [19] P. Li, Y.M. Zhang, Q. Lin, J.Q. Li, T.B. Wei, A novel colorimetric HSO4 sensor in aqueous media, Spectrochim. Acta A 80 (2012) 152–157. [20] T.B. Wei, P. Zhang, B.B. Shi, P. Chen, Q. Lin, J. Liu, Y.M. Zhang, A highly selective chemosen sor for colorimet ric detection of Fe3+ and fluorescence turn-on response of Zn2+, Dyes Pigments 97 (2013) 297–302. [21] Q. Lin, P. Chen, J. Liu, Y.P. Fu, Y.M. Zhang, T.B. Wei, Colorimetric chemosensor and test kit for detection copper(II) cations in aqueous solution with specific selectivity and high sensitivity, Dyes Pigments 98 (2013) 100–105. [22] Y.M. Zhang, B.B. Shi, P. Zhang, P. Chen, Q. Lin, T.B. Wei, A highly selective dualchannel Hg2+ chemosensor based on an easy to prepare double naphthalene Schiff base, Sci. China Chem. 56 (2013) 612–618. [23] M. Santra, K.H. Ahn, A ‘‘ reactive ’’ ratiometric fluorescent probe for mercury species, Org. Lett. 13 (2011) 3422–3425. [24] P. Wang, C. Klein, R.H. Baker, S.M. Zakeeruddin, M.G. tzel, A high molar extinction coefficient sensitizer for stable dye-sensitized solar cells, J. Am. Chem. Soc. 127 (2005) 808–809. [25] K. Benelhadj, J. Massue, P. Retailleau, G. Ulrich, R. Ziessel, 2-(20 Hydroxyphenyl) benzimidazole and 9,10-phenanthroimidazole chelates and borate complexes: solution-and solid-state emitters, Org. Lett. 15 (2013) 2918–2921. [26] T. Tao, W. Assenmacher, H. Peterlik, G. Schnakenburg, K. Heinz, Dötz, pyridinebridged benzimidazolium salts: synthesis, aggregation, and application as phase-transfer catalysts, Angew. Chem. Int. Ed. 47 (2008) 7127–7131.
