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A phosphorescent chemosensor for Cu2 + based on cationic iridium(III) complexes
Inorganic Chemistry Communications 16 (2012) 1–3
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
A phosphorescent chemosensor for Cu 2 + based on cationic iridium(III) complexes Hong Yang a,⁎, Yachao Zhu a, Liutao Li a, Zhiguo Zhou b, Shiping Yang a,⁎ a b
The Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234, PR China Department of Chemistry, Fudan University, Shanghai, 200233, PR China
a r t i c l e
i n f o
Article history: Received 17 August 2011 Accepted 2 November 2011 Available online 15 November 2011 Keywords: Copper ion Iridium complex Phosphorescence Chemosensor
a b s t r a c t A cationic phosphorescent iridium complex 1 was synthesized, which can selectively detect Cu 2 + confirmed by the luminescence spectra titration. In the presence of Cu 2 +, the obvious decrease of the luminescence intensity at 600 nm was investigated. The complex has been shown to display high selectivity for Cu2 + over other metal ions. The strong selective coordination interaction with Cu2 + is responsible for the significant change of the luminescence spectra, which is further confirmed by ESI-MS. © 2011 Elsevier B.V. All rights reserved.
Cu 2 + is the third in abundance among the essential heavy metal ions in the human body and plays a significant role in many fundamental physiological processes ranging from bacteria to mammals [1,2]. If the levels of Cu 2 + exceed cellular needs, it will be toxic to biological systems [3,4]. Excessive Cu 2 + can cause oxidative stress and disorders associated with neurodegenerative diseases, such as Alzheimer's disease, Menkes and Wilson diseases, and so on [5,6]. Due to their simplicity, easy visualization and high sensitivity, fluorescent chemosensors for Cu 2 + are actively investigated [7–9]. Recently, phosphorescent iridium complexes have attracted great interest because of their advantages including significant Stoke shifts, long-time phosphorescence emission, easy chemical modification, highly fluorescent quantum yield and so on [10,11]. They have been widely used for the detection for F −, [12,13] Ca 2 +, [14] transition metal ions such as Zn 2 +/Cd 2 +, [15,16] Hg 2 +, [17,18] Pb 2 +, [19] Ag +,[20] small molecules and biomolecules such as amino acids, [21,22] DNA [23] and proteins [24]. However, their application for phosphorescent chemosensor of Cu 2 + is quite rare [15,16,25]. Herein, we present a novel highly selective “turn-off”type chemosensor to Cu 2 + based on iridium complex with many coordination sites. The synthetic route of 1 was outlined in Scheme 1. 2 was obtained from the corresponding chloride-bridged dimer [(ppy)2Ir (μ-Cl)2(ppy)2]. Reaction of 2 with pyridin-2-ylmethanamine under basic medium gave 1 in the yield of 82%. Fig. 1 showed the absorption and luminescence spectra of 1 (10 μM) in C2H5OH/H2O
⁎ Corresponding authors. E-mail address: [email protected] (S. Yang). 1387-7003/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2011.11.006
(1:99 v/v) mixture solution at room temperature. The UV–vis spectrum is featured by intense absorptions at 220–330 nm together with a low-energy absorption band at 350–420 nm. The highenergy bands are most probably assigned to spin-allowed interligand LC (π → π*) transitions and the low-energy absorption bands are due to mixed singlet and triplet metal-to-ligand charge-transfer ( 1MLCT and 3MLCT) states. Upon excitation at 365 nm in C2H5OH/H2O (1:99 v/v) mixture solution under ambient condition, 1 presented luminescence centered at 600 nm in the orange region, which is attributed to the emission state of 3MLCT. The changes in the luminescence spectrum of 1 with the addition of Cu 2 + ion in C2H5OH/H2O (1:99 v/v) mixture solution were shown in Fig. 2. Upon addition of about 1.0 equiv. of Cu 2 +, the luminescence of 1 was quenched almost completely, which perhaps is attributed to the paramagnetic property of Cu 2 +. The nonlinear fitting of the titration curve assumed a 1:1 stoichiometry for Cu 2 + and 1 with an association constant Ka value of 3.4 × 10 5 M − 1 [26–29]. This binding mode is supported by the presence of a peak at m/z 968.3 (Calcd. 968.1) corresponding to [1-Cu 2 +-NO3−] + in the mass spectrum of a mixture of 1 and 2 equiv. of Cu(NO3)2, respectively (Fig. 3). Therefore, in accordance with the 1:1 stoichiometry and the coordination number of four for Cu 2 +, N and O atoms on the amide group, N atom on the pyridine unit are the most likely coordination sites of 1 for Cu 2 + (Fig. 3 inset). Selectivity is an important characteristic of chemosensors. We have further evaluated the selectivity of 1 for Cu 2 + over the other main group, related heavy, and transition metal ions. The unique luminescence change with almost disappearing of emission of 1 was observed only by the addition of Cu 2 + compared with addition of excess of other metal ions (such as Mn 2 +, Ca 2 +, Cd 2 +,
2
H. Yang et al. / Inorganic Chemistry Communications 16 (2012) 1–3
N N
H N
i
N Ir
Cl O
N
N
H N
Cl O
2
N
ii
Ir N
N PF6-
2
H N
NH O
N
2
PF6-
1 (i) Ir2(ppy)4Cl2 (ppy = 2-phenyl-pyridine), KPF6, CH2Cl2/CH3OH (1:1, V/V), reflux, 70%; (ii) pyridin-2-ylmethanamine, KI, Et3N, THF, 60 oC, 82% Scheme 1. Synthesis of chemosensor 1.
Ag +, Co 2 +, Cr 3 +, Hg 2 +, Zn 2 +, Pb 2 +, Ni 2 +, Fe 3 + and Mg 2 +) as shown in Figs. 4 and 5. In the competitive experiment, excessive other metal ions also cannot influence the special response of 1 towards copper ion obviously. Interestingly, Zn 2 + can increase the fluorescence intensity of 1. In conclusion, a new iridium complex 1 has been synthesized for the detection of copper ions. 1 exhibits significant changes of optical property and excellent selectivity towards Cu 2 + over other metal ions based on the highly selective coordination interaction in the aqueous solution (C2H5OH/H2O = 1:99, V/V). This offers a new strategy for designing phosphorescent chemosensors based on heavymetal complexes. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (20801015 and 50802059) and the Leading Academic Discipline Project of Shanghai Normal University (DZL806). Appendix A. Supplementary data Supplementary data to this article can be found online at doi:10. 1016/j.inoche.2011.11.006. References [1] M.C. Linder, M. Hazegh-Azam, Copper biochemistry and molecular biology, Am. J. Clin. Nutr. 63 (1996) 797S–811S. [2] R. Uauy, M. Olivares, M. Gonzalez, Essentiality of copper in humans, Am. J. Clin. Nutr. 67 (1998) 952S–959S. [3] Z.L. Harris, J.D. Gitlin, Genetic and molecular basis for copper toxicity, Am. J. Clin. Nutr. 63 (1996) 836S–841S. [4] I.H. Scheinberg, I. Sternlieb, Wilson disease and idiopathic copper toxicosis, Am. J. Clin. Nutr. 63 (1996) 842S–845S.
Fig. 1. Absorption (left) and luminescence (right) spectra of complex 1 in C2H5OH/H2O (1:99 v/v) mixture solution.
[5] G. Multhaup, A. Schlicksupp, L. Hesse, D. Beher, T. Ruppert, C.L. Masters, K. Beyreuther, The amyloid precursor protein of Alzheimer's disease in the reduction of copper(II) to copper(I), Science 271 (1996) 1406–1409. [6] R.A. Løvstad, A kinetic study on the distribution of Cu(II)-ions between albumin and transferrin, BioMetals 17 (2004) 111–113. [7] Z. Xu, Y. Xiao, X. Qian, J. Cui, D. Cui, Ratiometric and selective fluorescent sensor for CuII based on internal charge transfer (ICT), Org. Lett. 7 (2005) 889–892. [8] Z. Xu, X. Qian, J. Cui, Colorimetric and ratiometric fluorescent chemosensor with a large red-shift in emission: Cu(II)-only sensing by deprotonation of secondary amines as receptor conjugated to naphthalimide fluorophore, Org. Lett. 7 (2005) 3029–3032. [9] S. Banthia, A. Samanta, A two-dimensional chromogenic sensor as well as fluorescence inverter: selective detection of copper(ii) in aqueous medium, New J. Chem. 29 (2005) 1007–1010. [10] C. Ulbricht, B. Beyer, C. Friebe, A. Winter, U.S. Schubert, Recent developments in the application of phosphorescent iridium(III) complex systems, Adv. Mater. 21 (2009) 4418–4441. [11] Z.-q. Chen, Z.-q. Bian, C.-h. Huang, Functional IrIII complexes and their applications, Adv. Mater. 22 (2010) 1534–1539. [12] Q. Zhao, F. Li, S. Liu, M. Yu, Z. Liu, T. Yi, C. Huang, Highly selective phosphorescent chemosensor for fluoride based on an iridium(III) complex containing arylborane units, Inorg. Chem. 47 (2008) 9256–9264. [13] Y. You, S.Y. Park, A phosphorescent Ir(III) complex for selective fluoride ion sensing with a high signal-to-noise ratio, Adv. Mater. 20 (2008) 3820–3826. [14] M.-L. Ho, F.-M. Hwang, P.-N. Chen, Y.-H. Hu, Y.-M. Cheng, K.-S. Chen, G.-H. Lee, Y. Chi, P.-T. Chou, Design and synthesis of iridium(iii) azacrown complex: application as a highly sensitive metal cation phosphorescence sensor, Org. Biomol. Chem. 4 (2006) 98–103. [15] N. Zhao, Y.-H. Wu, H.-M. Wen, X. Zhang, Z.-N. Chen, Conversion from ILCT to LLCT/ MLCT excited state by heavy metal ion binding in iridium(III) complexes with functionalized 2,2′-bipyridyl ligands, Organometallics 28 (2009) 5603–5611. [16] J.C. Araya, J. Gajardo, S.A. Moya, P. Aguirre, L. Toupet, J.A.G. Williams, M. Escadeillas, H. Le Bozec, V. Guerchais, Modulating the luminescence of an iridium(III) complex incorporating a di(2-picolyl)anilino-appended bipyridine ligand with Zn2 + cations, New J. Chem. 34 (2010) 21–24. [17] Q. Zhao, T. Cao, F. Li, X. Li, H. Jing, T. Yi, C. Huang, A highly selective and multisignaling optical–electrochemical sensor for Hg2 + based on a phosphorescent iridium(III) complex, Organometallics 26 (2007) 2077–2081. [18] H. Yang, J. Qian, L. Li, Z. Zhou, D. Li, H. Wu, S. Yang, A selective phosphorescent chemodosimeter for mercury ion, Inorg. Chim. Acta 363 (2010) 1755–1759. [19] M.-L. Ho, Y.-M. Cheng, L.-C. Wu, P.-T. Chou, G.-H. Lee, F.-C. Hsu, Y. Chi, Probing Pb2 + cation via the iridium based phosphorescent dye, Polyhedron 26 (2007) 4886–4892.
Fig. 2. Changes in the luminescence spectra of 1 (10 μM) in C2H5OH/H2O (1:99 v/v) mixture solution with various amounts of Cu2 + ions (0–2.0 eq), λex = 365 nm.
H. Yang et al. / Inorganic Chemistry Communications 16 (2012) 1–3
3
Fig. 3. Electrospray mass spectrum of 1 with 2 equiv. of Cu2 +. Inset: The mechanism of chemosensor for Cu2 +.
[20] M. Schmittel, H. Lin, Luminescent iridium phenanthroline crown ether complex for the detection of silver(I) ions in aqueous media, Inorg. Chem. 46 (2007) 9139–9145. [21] H. Chen, Q. Zhao, Y. Wu, F. Li, H. Yang, T. Yi, C. Huang, Selective phosphorescence chemosensor for homocysteine based on an iridium(III) complex, Inorg. Chem. 46 (2007) 11075–11081.
[22] L. Xiong, Q. Zhao, H. Chen, Y. Wu, Z. Dong, Z. Zhou, F. Li, Phosphorescence imaging of homocysteine and cysteine in living cells based on a cationic iridium(III) complex, Inorg. Chem. 49 (2010) 6402–6408. [23] K.K.-W. Lo, M.-W. Louie, K.Y. Zhang, Design of luminescent iridium(III) and rhenium(I) polypyridine complexes as in vitro and in vivo ion, molecular and biological probes, Coord. Chem. Rev. 254 (2010) 2603–2622. [24] D.-L. Ma, W.-L. Wong, W.-H. Chung, F.-Y. Chan, P.-K. So, T.-S. Lai, Z.-Y. Zhou, Y.-C. Leung, K.-Y. Wong, A highly selective luminescent switch-on probe for histidine/histidine-rich proteins and its application in protein staining, Angew. Chem. Int. Ed. 47 (2008) 3735–3739. [25] Y. You, Y. Han, Y.-M. Lee, S.Y. Park, W. Nam, S.J. Lippard, Phosphorescent sensor for robust quantification of copper(II) ion, J. Am. Chem. Soc. 133 (2011) 11488–11491. [26] S.-K. Ko, Y.-K. Yang, J. Tae, I. Shin, In vivo monitoring of mercury ions using a rhodamine-based molecular probe, J. Am. Chem. Soc. 128 (2006) 14150–14155. [27] H. Yang, Z. Zhou, K. Huang, M. Yu, F. Li, T. Yi, C. Huang, Multisignaling optical– electrochemical sensor for Hg2 + based on a rhodamine derivative with a ferrocene unit, Org. Lett. 9 (2007) 4729–4732. [28] B. Tang, Y. Xing, P. Li, N. Zhang, F. Yu, G. Yang, A rhodamine-based fluorescent probe containing a Se–N bond for detecting thiols and its application in living cells, J. Am. Chem. Soc. 129 (2007) 11666–11667. [29] S. Kenmoku, Y. Urano, H. Kojima, T. Nagano, Development of a highly specific rhodamine-based fluorescence probe for hypochlorous acid and its application to real-time imaging of phagocytosis, J. Am. Chem. Soc. 129 (2007) 7313–7318.
Fig. 4. Luminescent response of 1 (10 μM) to Cu2 + (20 μM) with or without various metal ions (20 μM) in C2H5OH/H2O (1:99 v/v) mixture solution. Bars represent the luminescent intensity at 600 nm. Blank bars represent the addition of metal cations to the solution of 1. Black bars represent addition of Cu2 + to the above solution. λex = 365 nm.
Fig. 5. Phosphorescent photos observed from 1 (10 μM) in the presence of different cations (20 μM), excited by a portable lamp (~365 nm).
Contents lists available at SciVerse ScienceDirect
Inorganic Chemistry Communications journal homepage: www.elsevier.com/locate/inoche
A phosphorescent chemosensor for Cu 2 + based on cationic iridium(III) complexes Hong Yang a,⁎, Yachao Zhu a, Liutao Li a, Zhiguo Zhou b, Shiping Yang a,⁎ a b
The Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, Shanghai 200234, PR China Department of Chemistry, Fudan University, Shanghai, 200233, PR China
a r t i c l e
i n f o
Article history: Received 17 August 2011 Accepted 2 November 2011 Available online 15 November 2011 Keywords: Copper ion Iridium complex Phosphorescence Chemosensor
a b s t r a c t A cationic phosphorescent iridium complex 1 was synthesized, which can selectively detect Cu 2 + confirmed by the luminescence spectra titration. In the presence of Cu 2 +, the obvious decrease of the luminescence intensity at 600 nm was investigated. The complex has been shown to display high selectivity for Cu2 + over other metal ions. The strong selective coordination interaction with Cu2 + is responsible for the significant change of the luminescence spectra, which is further confirmed by ESI-MS. © 2011 Elsevier B.V. All rights reserved.
Cu 2 + is the third in abundance among the essential heavy metal ions in the human body and plays a significant role in many fundamental physiological processes ranging from bacteria to mammals [1,2]. If the levels of Cu 2 + exceed cellular needs, it will be toxic to biological systems [3,4]. Excessive Cu 2 + can cause oxidative stress and disorders associated with neurodegenerative diseases, such as Alzheimer's disease, Menkes and Wilson diseases, and so on [5,6]. Due to their simplicity, easy visualization and high sensitivity, fluorescent chemosensors for Cu 2 + are actively investigated [7–9]. Recently, phosphorescent iridium complexes have attracted great interest because of their advantages including significant Stoke shifts, long-time phosphorescence emission, easy chemical modification, highly fluorescent quantum yield and so on [10,11]. They have been widely used for the detection for F −, [12,13] Ca 2 +, [14] transition metal ions such as Zn 2 +/Cd 2 +, [15,16] Hg 2 +, [17,18] Pb 2 +, [19] Ag +,[20] small molecules and biomolecules such as amino acids, [21,22] DNA [23] and proteins [24]. However, their application for phosphorescent chemosensor of Cu 2 + is quite rare [15,16,25]. Herein, we present a novel highly selective “turn-off”type chemosensor to Cu 2 + based on iridium complex with many coordination sites. The synthetic route of 1 was outlined in Scheme 1. 2 was obtained from the corresponding chloride-bridged dimer [(ppy)2Ir (μ-Cl)2(ppy)2]. Reaction of 2 with pyridin-2-ylmethanamine under basic medium gave 1 in the yield of 82%. Fig. 1 showed the absorption and luminescence spectra of 1 (10 μM) in C2H5OH/H2O
⁎ Corresponding authors. E-mail address: [email protected] (S. Yang). 1387-7003/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.inoche.2011.11.006
(1:99 v/v) mixture solution at room temperature. The UV–vis spectrum is featured by intense absorptions at 220–330 nm together with a low-energy absorption band at 350–420 nm. The highenergy bands are most probably assigned to spin-allowed interligand LC (π → π*) transitions and the low-energy absorption bands are due to mixed singlet and triplet metal-to-ligand charge-transfer ( 1MLCT and 3MLCT) states. Upon excitation at 365 nm in C2H5OH/H2O (1:99 v/v) mixture solution under ambient condition, 1 presented luminescence centered at 600 nm in the orange region, which is attributed to the emission state of 3MLCT. The changes in the luminescence spectrum of 1 with the addition of Cu 2 + ion in C2H5OH/H2O (1:99 v/v) mixture solution were shown in Fig. 2. Upon addition of about 1.0 equiv. of Cu 2 +, the luminescence of 1 was quenched almost completely, which perhaps is attributed to the paramagnetic property of Cu 2 +. The nonlinear fitting of the titration curve assumed a 1:1 stoichiometry for Cu 2 + and 1 with an association constant Ka value of 3.4 × 10 5 M − 1 [26–29]. This binding mode is supported by the presence of a peak at m/z 968.3 (Calcd. 968.1) corresponding to [1-Cu 2 +-NO3−] + in the mass spectrum of a mixture of 1 and 2 equiv. of Cu(NO3)2, respectively (Fig. 3). Therefore, in accordance with the 1:1 stoichiometry and the coordination number of four for Cu 2 +, N and O atoms on the amide group, N atom on the pyridine unit are the most likely coordination sites of 1 for Cu 2 + (Fig. 3 inset). Selectivity is an important characteristic of chemosensors. We have further evaluated the selectivity of 1 for Cu 2 + over the other main group, related heavy, and transition metal ions. The unique luminescence change with almost disappearing of emission of 1 was observed only by the addition of Cu 2 + compared with addition of excess of other metal ions (such as Mn 2 +, Ca 2 +, Cd 2 +,
2
H. Yang et al. / Inorganic Chemistry Communications 16 (2012) 1–3
N N
H N
i
N Ir
Cl O
N
N
H N
Cl O
2
N
ii
Ir N
N PF6-
2
H N
NH O
N
2
PF6-
1 (i) Ir2(ppy)4Cl2 (ppy = 2-phenyl-pyridine), KPF6, CH2Cl2/CH3OH (1:1, V/V), reflux, 70%; (ii) pyridin-2-ylmethanamine, KI, Et3N, THF, 60 oC, 82% Scheme 1. Synthesis of chemosensor 1.
Ag +, Co 2 +, Cr 3 +, Hg 2 +, Zn 2 +, Pb 2 +, Ni 2 +, Fe 3 + and Mg 2 +) as shown in Figs. 4 and 5. In the competitive experiment, excessive other metal ions also cannot influence the special response of 1 towards copper ion obviously. Interestingly, Zn 2 + can increase the fluorescence intensity of 1. In conclusion, a new iridium complex 1 has been synthesized for the detection of copper ions. 1 exhibits significant changes of optical property and excellent selectivity towards Cu 2 + over other metal ions based on the highly selective coordination interaction in the aqueous solution (C2H5OH/H2O = 1:99, V/V). This offers a new strategy for designing phosphorescent chemosensors based on heavymetal complexes. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (20801015 and 50802059) and the Leading Academic Discipline Project of Shanghai Normal University (DZL806). Appendix A. Supplementary data Supplementary data to this article can be found online at doi:10. 1016/j.inoche.2011.11.006. References [1] M.C. Linder, M. Hazegh-Azam, Copper biochemistry and molecular biology, Am. J. Clin. Nutr. 63 (1996) 797S–811S. [2] R. Uauy, M. Olivares, M. Gonzalez, Essentiality of copper in humans, Am. J. Clin. Nutr. 67 (1998) 952S–959S. [3] Z.L. Harris, J.D. Gitlin, Genetic and molecular basis for copper toxicity, Am. J. Clin. Nutr. 63 (1996) 836S–841S. [4] I.H. Scheinberg, I. Sternlieb, Wilson disease and idiopathic copper toxicosis, Am. J. Clin. Nutr. 63 (1996) 842S–845S.
Fig. 1. Absorption (left) and luminescence (right) spectra of complex 1 in C2H5OH/H2O (1:99 v/v) mixture solution.
[5] G. Multhaup, A. Schlicksupp, L. Hesse, D. Beher, T. Ruppert, C.L. Masters, K. Beyreuther, The amyloid precursor protein of Alzheimer's disease in the reduction of copper(II) to copper(I), Science 271 (1996) 1406–1409. [6] R.A. Løvstad, A kinetic study on the distribution of Cu(II)-ions between albumin and transferrin, BioMetals 17 (2004) 111–113. [7] Z. Xu, Y. Xiao, X. Qian, J. Cui, D. Cui, Ratiometric and selective fluorescent sensor for CuII based on internal charge transfer (ICT), Org. Lett. 7 (2005) 889–892. [8] Z. Xu, X. Qian, J. Cui, Colorimetric and ratiometric fluorescent chemosensor with a large red-shift in emission: Cu(II)-only sensing by deprotonation of secondary amines as receptor conjugated to naphthalimide fluorophore, Org. Lett. 7 (2005) 3029–3032. [9] S. Banthia, A. Samanta, A two-dimensional chromogenic sensor as well as fluorescence inverter: selective detection of copper(ii) in aqueous medium, New J. Chem. 29 (2005) 1007–1010. [10] C. Ulbricht, B. Beyer, C. Friebe, A. Winter, U.S. Schubert, Recent developments in the application of phosphorescent iridium(III) complex systems, Adv. Mater. 21 (2009) 4418–4441. [11] Z.-q. Chen, Z.-q. Bian, C.-h. Huang, Functional IrIII complexes and their applications, Adv. Mater. 22 (2010) 1534–1539. [12] Q. Zhao, F. Li, S. Liu, M. Yu, Z. Liu, T. Yi, C. Huang, Highly selective phosphorescent chemosensor for fluoride based on an iridium(III) complex containing arylborane units, Inorg. Chem. 47 (2008) 9256–9264. [13] Y. You, S.Y. Park, A phosphorescent Ir(III) complex for selective fluoride ion sensing with a high signal-to-noise ratio, Adv. Mater. 20 (2008) 3820–3826. [14] M.-L. Ho, F.-M. Hwang, P.-N. Chen, Y.-H. Hu, Y.-M. Cheng, K.-S. Chen, G.-H. Lee, Y. Chi, P.-T. Chou, Design and synthesis of iridium(iii) azacrown complex: application as a highly sensitive metal cation phosphorescence sensor, Org. Biomol. Chem. 4 (2006) 98–103. [15] N. Zhao, Y.-H. Wu, H.-M. Wen, X. Zhang, Z.-N. Chen, Conversion from ILCT to LLCT/ MLCT excited state by heavy metal ion binding in iridium(III) complexes with functionalized 2,2′-bipyridyl ligands, Organometallics 28 (2009) 5603–5611. [16] J.C. Araya, J. Gajardo, S.A. Moya, P. Aguirre, L. Toupet, J.A.G. Williams, M. Escadeillas, H. Le Bozec, V. Guerchais, Modulating the luminescence of an iridium(III) complex incorporating a di(2-picolyl)anilino-appended bipyridine ligand with Zn2 + cations, New J. Chem. 34 (2010) 21–24. [17] Q. Zhao, T. Cao, F. Li, X. Li, H. Jing, T. Yi, C. Huang, A highly selective and multisignaling optical–electrochemical sensor for Hg2 + based on a phosphorescent iridium(III) complex, Organometallics 26 (2007) 2077–2081. [18] H. Yang, J. Qian, L. Li, Z. Zhou, D. Li, H. Wu, S. Yang, A selective phosphorescent chemodosimeter for mercury ion, Inorg. Chim. Acta 363 (2010) 1755–1759. [19] M.-L. Ho, Y.-M. Cheng, L.-C. Wu, P.-T. Chou, G.-H. Lee, F.-C. Hsu, Y. Chi, Probing Pb2 + cation via the iridium based phosphorescent dye, Polyhedron 26 (2007) 4886–4892.
Fig. 2. Changes in the luminescence spectra of 1 (10 μM) in C2H5OH/H2O (1:99 v/v) mixture solution with various amounts of Cu2 + ions (0–2.0 eq), λex = 365 nm.
H. Yang et al. / Inorganic Chemistry Communications 16 (2012) 1–3
3
Fig. 3. Electrospray mass spectrum of 1 with 2 equiv. of Cu2 +. Inset: The mechanism of chemosensor for Cu2 +.
[20] M. Schmittel, H. Lin, Luminescent iridium phenanthroline crown ether complex for the detection of silver(I) ions in aqueous media, Inorg. Chem. 46 (2007) 9139–9145. [21] H. Chen, Q. Zhao, Y. Wu, F. Li, H. Yang, T. Yi, C. Huang, Selective phosphorescence chemosensor for homocysteine based on an iridium(III) complex, Inorg. Chem. 46 (2007) 11075–11081.
[22] L. Xiong, Q. Zhao, H. Chen, Y. Wu, Z. Dong, Z. Zhou, F. Li, Phosphorescence imaging of homocysteine and cysteine in living cells based on a cationic iridium(III) complex, Inorg. Chem. 49 (2010) 6402–6408. [23] K.K.-W. Lo, M.-W. Louie, K.Y. Zhang, Design of luminescent iridium(III) and rhenium(I) polypyridine complexes as in vitro and in vivo ion, molecular and biological probes, Coord. Chem. Rev. 254 (2010) 2603–2622. [24] D.-L. Ma, W.-L. Wong, W.-H. Chung, F.-Y. Chan, P.-K. So, T.-S. Lai, Z.-Y. Zhou, Y.-C. Leung, K.-Y. Wong, A highly selective luminescent switch-on probe for histidine/histidine-rich proteins and its application in protein staining, Angew. Chem. Int. Ed. 47 (2008) 3735–3739. [25] Y. You, Y. Han, Y.-M. Lee, S.Y. Park, W. Nam, S.J. Lippard, Phosphorescent sensor for robust quantification of copper(II) ion, J. Am. Chem. Soc. 133 (2011) 11488–11491. [26] S.-K. Ko, Y.-K. Yang, J. Tae, I. Shin, In vivo monitoring of mercury ions using a rhodamine-based molecular probe, J. Am. Chem. Soc. 128 (2006) 14150–14155. [27] H. Yang, Z. Zhou, K. Huang, M. Yu, F. Li, T. Yi, C. Huang, Multisignaling optical– electrochemical sensor for Hg2 + based on a rhodamine derivative with a ferrocene unit, Org. Lett. 9 (2007) 4729–4732. [28] B. Tang, Y. Xing, P. Li, N. Zhang, F. Yu, G. Yang, A rhodamine-based fluorescent probe containing a Se–N bond for detecting thiols and its application in living cells, J. Am. Chem. Soc. 129 (2007) 11666–11667. [29] S. Kenmoku, Y. Urano, H. Kojima, T. Nagano, Development of a highly specific rhodamine-based fluorescence probe for hypochlorous acid and its application to real-time imaging of phagocytosis, J. Am. Chem. Soc. 129 (2007) 7313–7318.
Fig. 4. Luminescent response of 1 (10 μM) to Cu2 + (20 μM) with or without various metal ions (20 μM) in C2H5OH/H2O (1:99 v/v) mixture solution. Bars represent the luminescent intensity at 600 nm. Blank bars represent the addition of metal cations to the solution of 1. Black bars represent addition of Cu2 + to the above solution. λex = 365 nm.
Fig. 5. Phosphorescent photos observed from 1 (10 μM) in the presence of different cations (20 μM), excited by a portable lamp (~365 nm).