338 Bull. Korean Chem. Soc.2011, Vol. 32, No. 1Notes DOI 10.5012/bkcs.2011.32.1.338
Synthesis and Characterization
of a Rapid and Highly Selective Fluorescent Hg2+ Sensor in Aqueous Media
Xiao Liang Li, Yong Wu He, and Sung Ik Yang*
Department of Applied Chemistry, Kyung Hee University, Yongin 446-701, Korea. *E-mail: siyang@khu.ac.kr
Received July 16, 2010, Accepted November 10, 2010
Key Words: Fluorescent chemonsor, Pyrene, Hg2+ ion
Scheme 1. Synthesis of fluorescent nsor Py-1
英国语言
400 450
Wavelength (nm)
F
l
u
o
r
e
s
c
e
n
c
e
i
n
t
e
n
s
i
t
贵富y
(
a
.
u
炒香菜的做法大全.
)
Figure 1. Fluorescence spectra of fluorescent nsor Py-1 (1 μM) in H2O/ CH3CN (1:1, v/v) in the prence of Hg2+ Ag+, Cd2+, Cu2+, Fe3+, Ni2+, Pb2+, Zn2+ (10 equiv).
Heavy metal ions po risks to human health and environ-ment.1 Among the metal ions, Hg2+ is one of the most important toxic metal ions, becau of its wide u in electrical equipment, catalysts, and paints, after which it is relead into environment.2 Thus, it is highly desirable to develop a Hg2+ nsor applicable for industrial waste sites and the environment. Among known metal ion nsors, fluorescent nsors have drawn much interest owing to their potential for on-site and real-time detection of toxic metal ions with low detection limits.1,3 A number of fluo-rescent Hg2+ nsors have been reported, including small mole-cules, who quenching process is bad on Hg2+ coordina-tion.4,5 To enhance the nsitivity, however, it is esntial to design a nsor that does not quench fluorescence upon metal ion recognition. Although there have been reports of a fluo-rescent turn-on Hg2+ nsor by veral groups, still there are some drawbacks such as multiple synthesis steps from commer-cially available materials and low overall synthetic yield.6-10 Hence, it is desirable to develop new types of simple fluorescent nsors applicable in a variety of areas such as environmental monitoring and diagnostic analysis.
The pyrene is one of the most widely ud fluorescent dyes in the design of fluorescent nsors for
heavy metal ions.11 Be-cau of strong thiophilic affinity of Hg2+, carbamoyl thiourea derivatives have showed good binding property to Hg2+ in fluo-rescent nsors.12,13 But there are still some drawbacks including interference from other metal ion12,13 or irreversibility.14
In the prent study, we report the synthesis and metal-bind-ing properties of new pyrene-bad Hg2+ fluorescent nsor Py-1. The fluorescent Hg2+ nsor Py-1 was prepared in one step from commercially available 1-pyrenemethylamine hydrochlo-ride and benzoyl isothiocyanate in high yield. (Scheme 1) We found that this turn-on nsor Py-1 exhibits a rapid respon and an extremely good lectivity toward Hg2+ compared with other metals in aqueous solution. We believe that it could have application in a variety of areas, such as environmental moni-toring and diagnostic analysis.
Py-1 was prepared according to Scheme 1. Under argon, a solution of 1-pyrenemethylamine hydrochloride (0.268 g, 1 mmol), benzoyl isothiocyanate (0.163 g, 1 mmol) in CH3CN (20 mL) was refluxed for 36 h. Then 30 ml CHCl3 was added, and the solution was filtered. The filtrate was removed by rotary evaporation to produce a yellow-orange solid. The crude pro-duct was purified by column chromatography (silica, CH2Cl2/ hexane, 1/2) to give 0.296 g as yellow solid in 75% yield.15 The molecular structure of Py-1 was confirmed by mass spectro-metry and NMR. Fluorescence spec
tra were recorded with a FL-4500 fluorometer. Stock solutions (1.00 mM) of metal salts were prepared in H2O/CH3CN (1:1, v/v). Stock solutions of free Py-1 (1.00 mM) were prepared in CH3CN.
The effects of metal ion addition on the absorption and fluo-rescence properties of Py-1 in CH3CN/H2O (1/1) were investi-gated to evaluate the metal ion binding properties of the nsor. We did not obrve any changes in absorption spectra upon addition of metal ions except for Ag+. The fluorescence spectra of Py-1 (c = 10‒6 M) were recorded following 342 nm excita-tion. Figure 1 shows the fluorescence spectra of Py-1 upon the addition of various metal ions, Ag+, Cd2+, Cu2+, Fe3+, Ni2+, Pb2+, Zn2+, and Hg2+. In the abnce of metal ion, Py-1 exhibited a very weak fluorescence intensity compared with that of pyrene owing to efficient photo-induced electron transfer from the metal binding site to the fluorescent unit. When Hg2+ was intro-duced to a 1 μM Py-1, a 23-fold fluorescence intensity enhance-ment was obrved, a result of inhibition of the PET quenching pathway. On the other hand, little fluorescence enhancement
新年的歌曲Notes
Bull. Korean Chem. Soc. 2011, Vol. 32, No. 1 339
400 450 500
Wavelength (nm)
F l u o r e s c e n c e i n t e n s i t y (a . u .)
Figure 2. Fluorescence titration spectra of fluorescent nsor Py-1 (1 μM) in H 2O/CH 3CN (1:1, v/v) upon addition of various amounts
of Hg 2+
(0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 equiv).
N
NH
O S N HN O
S Hg Figure 3. Propod geometry of the complexes.
Ag Cd Cu Fe Ni Pb Zn Hg
F l u o r e s c e n c e i n t e n s i t y (a . u .)
Figure 4. Selectivity and competition property of fluorescent nsor Py-1 over the metal ions of interest. Gray bars: addition of 10 equiv of Ag +, Cd 2+, Cu 2+, Fe 3+, Ni 2+, Pb 2+, Zn 2+, Hg 2+, to the solution; Black Bars:
addition of 10 equiv of Ag + + Hg 2+, Cd 2+ + Hg 2+, Cu 2+ + Hg 2+, Fe 3+
+Hg 2+, Ni 2+ + Hg 2+, Pb 2+ + Hg 2+, Zn 2+ + Hg 2+
, respectively in H 2O/ CH 3CN (1:1, v/v).
was obrved for other metal ions. The results indicate that the fluorescence nsor Py-1 exhibits a good lectivity toward Hg 2+ over other metals in aqueous solutions. The fluorescence spectrum of Py-1 in the prence of Hg 2+ exhibits similar to that of pyrene monomer, indicating that there is no dimer forma-tion upon Hg 2+ ion complex.
Titration experiments were performed with 1.0 μmol solu-tions of fluorescent nsor Py-1 and various concentrations of Hg 2+ in H 2O/CH 3CN (1:1, v/v). Figure 2 illustrate the fluo-rescence titration spectra of Py-1 (1 μM) upon addition of vari-ous amounts of Hg 2+
(0, 0.05, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0 equivalents). It can be en that the flu
o-rescence intensity increas continuously with increasing Hg 2+ concentration. The int shows the fluorescence titration profile of Py-1 at 390 nm upon addition of Hg 2+. The maximum point appears at the mole fraction of 0.70 in a Job’s plot, suggesting that the Py-1 forms a 2:1 ligand-to-metal complex. Mass spectro-metry data also confirmed the formation of 2:1 complex. To elucidate the binding mechanism of Py-1-Hg 2+ complex, IR spectrum was measured in solid form. Upon addition of 10 equi-valents of Hg 2+, the amide carbonyl band (1698 cm ‒1) of Py-1 shifts to a lower frequency (1633 cm ‒1), indicating that the amide
carbonyl participates in coordination with Hg 2+. In addition, 1
H NMR spectra also showed that the proton on thioamide was disappeared upon addition of Hg 2+, which indicate that the strong
interactions between Hg 2+ and the sulfur atom of the thioamide group (Figure 312,13). To examine the reversibility of Py-1, excess
of EDTA was added to the Py-1-Hg 2+
complex that exhibited weak fluorescence intensity, demonstrating reversibility to free Hg 2+ ion.
Figure 4 reprents the lectivity and completion property of Py-1 over the metal ions of interest (Gray bars: addition of 10 equivalents of Ag +, Cd 2+, Cu 2+, Fe 3+, Ni 2+, Pb 2+, Zn 2+, Hg 2+,
to the solution;. Black bars: addition of 10 equiv of Ag ++ Hg 2+
, Cd 2++ Hg 2+, Cu 2++ Hg 2+, Fe 3++ Hg 2+, Ni 2++ Hg 2+, Pb 2++ Hg 2+, Zn 2++ Hg 2+, Hg 2++ Hg 2+, respectively, in H 2O/CH 3CN (1:1, v/v)). All data (F ) were normalized with respect to the emission of the free dye (F o ). According to competition experiments, other me-tal ions did not show any interference with Hg 2+ lectivity.
Even addition of paramagnetic Ni 2+, Cu 2+, and Fe 3+
, which are well-known fluorescence quencher, did little to quench fluore-scence. The results demonstrate the applicability of the fluore-scent nsor Py-1 for Hg 2+
specific nsing in the environment.In conclusion, we have synthesized a pyrene-bad fluore-scent nsor, Py-1, and characterized its metal-binding pro-perties. We found that fluorescent nsor Py-1 exhibits a rapid respon and an extremely good lectivity toward Hg 2+ over other metal ions in aqueous solution.
Acknowledgments. This work was supported by Mid-career Rearcher Program through NRF grant funded by the MEST (No. 2009-0083867).
References
1.(a) Czarnik, A. W. Fluorescent Chemonsors for Ion and Mole-cule Recognition ; Ed.; American Chemical Society: Washington, DC, 1993. (b) de Silva, A. P.; Fox, D. B.; Huxley, A. J. M. Moody, T. S. Coord. Chem. Rev. 2000, 205, 41. (c) de Silva, A. P.; Guna-ratne, H. Q. N.; Gunnlaugsson, T.; Huxley, A. J. M.; McCoy, C. P.; Rademacher, J. T.; Rice, T. E. Chem. Rev. 1997, 97, 1515.
2.von Burg, R.; Greenwood, M. R. Metals and Their Compounds in
the Environment ; Merian, E., Ed.; VCH: Weinheim, 1991; pp
340 Bull. Korean Chem. Soc.2011, Vol. 32, No. 1Notes
1045-1088.
3.(a) Aragoni, M. C.; Arca, M.; Bencini, A.; Blake, A. J.; Caltagirone,
C.; Decortes, A.; Demartin, F.; Devillanova, F. A.; Faggi, E.; Dolci,
L. S.; Garau, A.; Isaia, F.; Lippolis, V.; Prodi, L.; Wilson, C.; Val-tancoli, B.; Zaccheroni, N. Dalton Trans. 2005, 2994. (b) Prodi, L.
New. J. Chem. 2005, 29, 20. (c) Fernandez, Y. D.; Gramatges, A.
P.; Amendola, V.; Foti, F.; Mangano, C.; Pallavicini, P.; Patroni, S.
Chem. Commun. 2004, 1650.
4.Praveen, L.; Ganga,V. B.; Thirumalai, R.; Sreeja,T.; Reddy, M.
L. P.; Luxmi Varma, R. Inorg. Chem. 2007, 46, 6277.
5.Fang, Z.; Liu, B. Tetrahedron Lett. 2008, 49, 2311.
6.Elizabeth, M. N.; Lippard, S. J. J. Am. Chem. Soc. 2003, 125, 14270.网络流行语英语
7.Elizabeth, M. N.; Lippard, S. J. J. Am. Chem. Soc. 2007, 129, 5910.
8.Liu, L.; Zhang, G.; X., J.; Zhang, D.; Zhu, D. Org. Lett.2008, 10,
4581.
9.Kim, S. H.; Kim, J. S.; Park, S. M.; Chang, S. K. Org. Lett. 2006,
8, 371.
10.Soh, J. H.; Swamy, K. M. K.; Kim, S. K.; Kim, S.; Lee, S. H.; Yoon,
J. Y. Tetrahedron Lett. 2007, 48, 5966.
11.(a) Choi, S. H.; Pang, K.; Kim, K.; Churchill, D. G. Inorg. Chem.
2007, 46, 10564. (b) Martínez, R.; Zapata, F.; Caballero, A.; Espi-nosa, A.; Tárraga, A.; Molina, P. Org. Lett.2006, 8, 3235. (c) Shi-raishi, Y.; Ishizumi, K.; Nishimura, G.; Hirai, T. J. Phys. Chem.
B2007, 111, 8812. (d) Zhou, Y.; Zhu, C. Y.; Gao, X. S.; You, X.爱情很美好
Y.; Yao, C. Org. Lett. 2010, 12, 2566. (e) Lin, W. C.; Wu, C. Y.;
Liu, Z. H.; Lin, C. Y.; Yen, Y. P. Talanta2010, 81, 1209. 12.Šandor, M.; Geistmann, F.; Schuster, M. Anal. Chim. Acta1999,
班级誓词
388, 19.
13.Hallale, O.; Bourne, S. A.; Koch, K. R. New J. Chem. 2005, 29,
淋浴房哪个品牌好1416.
14.Yang, Y. K.; Yook, K. J.; Tae, J. S. J. Am. Chem. Soc.2005, 127,
16760.
15.1H NMR (CDCl3, 300 MHz) 5.60 (d, 2H, J = 3 Hz), 7.46 (t, 2H,
J = 7.8 Hz), 7.58 (t, 1H, J = 7.5 Hz), 7.77 (d, 2H, J = 7.8 Hz), 8.00-
8.11 (m, 4H), 8.16-8.22 (m, 4H), 8.30 (d, 1H, J = 9.3 Hz), 9.12 (brs,
1H), 11.12 (brs, 1H); 13C NMR (CDCl3, 75 MHz) 48.3, 122.6, 124.6, 124.8, 125.0, 125.4, 125.5, 126.1, 127.2, 127.3, 127.7, 128.5, 129.0, 129.1, 129.2, 130.7, 131.2, 131.5, 133.5, 166.7, 179.5.
HRMS (70 eV, EI): m/z calcd for C25H18N2OS [M+] 394.1140, found 394.1135.
