Dalton Transactions
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This article can be cited before page numbers have been issued, to do this please use: C. Huang, H. Li, Y. Luo and L. Xu, Dalton Trans., 2014, DOI: 10.1039/C4DT00014E.
This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
www.rsc.org/dalton
Page 1 of 7
Dalton Transactions View Article Online
A bifunctional fluorescent probe NPM exhibits highly selective fluorescence turn-on for Hg2+ and turn-off for Cu2+ was synthesized.
Dalton Transactions Accepted Manuscript
Published on 18 March 2014. Downloaded by National Dong Hwa University Library on 29/03/2014 08:21:22.
DOI: 10.1039/C4DT00014E
Journal Name
Dalton Transactions
Page 2 of 7 Dynamic Article Links ► View Article Online
DOI: 10.1039/C4DT00014E
Cite this: DOI: 10.1039/c0xx00000x
PAPER
A naphthalimide-based bifunctional fluorescent probe for the differential detection of Hg2+ and Cu2+ in aqueous solution Chang-Bo Huang,a Hao-Ran Li,b Yuanyuan Luoc and Lin Xu*a 5
10
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX DOI: 10.1039/b000000x A novel fluorescent probe NPM based on naphthalimide was designed and synthesized. Interestingly, NPM exhibited highly selective fluorescence turn-on for Hg2+ and turn-off for Cu2+ in aqueous solution (10 mM HEPES, pH 7.5). Its fluorescence intensity was enhanced in a linear fashion with the concentration of Hg2+ and decreased in a nearly linear fashion with the concentration of Cu2+, respectively. Thus NPM could be potentially used for the quantification of Hg2+ and Cu2+ in aqueous solution. A series of model compounds were rationally designed and synthesized in order to explore the sensing mechanisms and binding modes of NPM with Hg2+ and Cu2+.
Introduction 15
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In the past few years, the development of fluorescent probes for detecting of heavy and transition metal (HTM) ions has attracted increasing attention owing to their simplicity, high sensitivity, and real-time detection.1,2 Among various HTMs, Hg2+ and Cu2+ are of particular interest due to their diverse physiological roles in living systems and their environmental impact. Hg2+, as one of the most highly toxic metals, could easily pass through biological membranes, such as skin, respiratory system, and gastrointestinal tissues. Excessive exposure and accumulation of mercury could lead to a number of severe health problems such as brain damage, kidney failure, and various cognitive and motion disorders.3 Cu2+ is the third most abundant of the essential nutrient required for normal cell growth and development, which plays critical roles in many biological processes, such as blood formation and functioning of various enzymes. Moreover, as well as its deficiency, Cu2+ overload can result in a variety of diseases, such as parkinson’s disease, epileptic seizures, renal and liver damage.4 Therefore, the development of new fluorescent probes for the determination of Hg2+ or Cu2+ is highly desirable. Up to now, many fluorescent probes for Hg2+ or Cu2+ were reported in recent literature.5,6 However, some of the reported fluorescent probes for Hg2+ or Cu2+ can be used only in organic medium or organic-containing solution, which limits their practical application.7 Even then, some of the reported fluorescent probes sometimes suffer from the intricate synthetic procedures.8 Therefore, there is a great need for the construction of new fluorescent probes that can detect Hg2+ or Cu2+ in aqueous solution by a simple synthetic approach. In recent years, the construction of multi-ion responsive fluorescent probes with multiple emission modes received immense interest.9 Fluorescent probes with a differential response towards multiple analytes are cost-effective and highly desirable for real-time applications. Moreover, such kind of fluorescent probes are indispensable for designing molecular logic gates and This journal is © The Royal Society of Chemistry [year]
50
55
60
65
70
molecular keypad lock devices.10 However, to the best of our knowledge, just two examples of bifunctional fluorescent probes capable of the simultaneous detection of Hg2+ and Cu2+ have been reported.11 For example, Yin and co-workers reported a bifunctional probe that can recognize Hg2+ and Cu2+ only in organic solvent (CH3CN).11a Tian and Zhu reported another bifunctional probe DCPP.11b Although its sensing properties could be investigated in organic-containing solution (containing 60% CH3CN as a co-solvent), DCPP displayed a relatively low sensitivity. The addition of five equivalents of Hg2+ to the solution of DCPP just induced 2.2-fold enhancement of the fluorescence intensity. Thus, it is still a challenge to develop bifunctional fluorescent probes for Hg2+ and Cu2+ in aqueous solution with high selectivity and sensitivity. Recently, we have reported a highly sensitive and selective naphthalimide-based Ag+ fluorescent probe NPQ, which contains a hydroxyquinoline moiety as part of the receptor.12 Herein, by the replacement of hydroxyquinoline moiety in NPQ with morpholine moiety, a novel fluorescent probe NPM was synthesized. Interestingly, NPM exhibited selective fluorescence turn-on response toward Hg2+ and selective fluorescence turn-off to Cu2+ in aqueous solution. With the aim to obtaining the insight into the possible sensing mechanisms and binding modes of
Scheme 1 The structures of fluorescent probes of NPQ, NPM and model compounds NBM and NPP.
[journal], [year], [vol], 00–00 | 1
Dalton Transactions Accepted Manuscript
Published on 18 March 2014. Downloaded by National Dong Hwa University Library on 29/03/2014 08:21:22.
www.rsc.org/xxxxxx
Page 3 of 7
Dalton Transactions View Article Online
DOI: 10.1039/C4DT00014E
600 O
piperazine
Cl X
200 2+
100
Wavelength (nm)
NPM with Hg and Cu , two model compounds (NBM and NPP) were designed and synthesized as shown in Scheme 1. 5
Results and discussion
10
45
pH effect of NPM
15
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25
30
35
40
The absorption and emissive properties of NPM on changing the pH were determined as shown in Fig. S1. A slight change in the absorption spectra of NPM was observed when the pH>7.0. However, when the pH
View Article Online View Journal
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: C. Huang, H. Li, Y. Luo and L. Xu, Dalton Trans., 2014, DOI: 10.1039/C4DT00014E.
This is an Accepted Manuscript, which has been through the Royal Society of Chemistry peer review process and has been accepted for publication. Accepted Manuscripts are published online shortly after acceptance, before technical editing, formatting and proof reading. Using this free service, authors can make their results available to the community, in citable form, before we publish the edited article. We will replace this Accepted Manuscript with the edited and formatted Advance Article as soon as it is available. You can find more information about Accepted Manuscripts in the Information for Authors. Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the Ethical guidelines still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains.
www.rsc.org/dalton
Page 1 of 7
Dalton Transactions View Article Online
A bifunctional fluorescent probe NPM exhibits highly selective fluorescence turn-on for Hg2+ and turn-off for Cu2+ was synthesized.
Dalton Transactions Accepted Manuscript
Published on 18 March 2014. Downloaded by National Dong Hwa University Library on 29/03/2014 08:21:22.
DOI: 10.1039/C4DT00014E
Journal Name
Dalton Transactions
Page 2 of 7 Dynamic Article Links ► View Article Online
DOI: 10.1039/C4DT00014E
Cite this: DOI: 10.1039/c0xx00000x
PAPER
A naphthalimide-based bifunctional fluorescent probe for the differential detection of Hg2+ and Cu2+ in aqueous solution Chang-Bo Huang,a Hao-Ran Li,b Yuanyuan Luoc and Lin Xu*a 5
10
Received (in XXX, XXX) Xth XXXXXXXXX 20XX, Accepted Xth XXXXXXXXX 20XX DOI: 10.1039/b000000x A novel fluorescent probe NPM based on naphthalimide was designed and synthesized. Interestingly, NPM exhibited highly selective fluorescence turn-on for Hg2+ and turn-off for Cu2+ in aqueous solution (10 mM HEPES, pH 7.5). Its fluorescence intensity was enhanced in a linear fashion with the concentration of Hg2+ and decreased in a nearly linear fashion with the concentration of Cu2+, respectively. Thus NPM could be potentially used for the quantification of Hg2+ and Cu2+ in aqueous solution. A series of model compounds were rationally designed and synthesized in order to explore the sensing mechanisms and binding modes of NPM with Hg2+ and Cu2+.
Introduction 15
20
25
30
35
40
45
In the past few years, the development of fluorescent probes for detecting of heavy and transition metal (HTM) ions has attracted increasing attention owing to their simplicity, high sensitivity, and real-time detection.1,2 Among various HTMs, Hg2+ and Cu2+ are of particular interest due to their diverse physiological roles in living systems and their environmental impact. Hg2+, as one of the most highly toxic metals, could easily pass through biological membranes, such as skin, respiratory system, and gastrointestinal tissues. Excessive exposure and accumulation of mercury could lead to a number of severe health problems such as brain damage, kidney failure, and various cognitive and motion disorders.3 Cu2+ is the third most abundant of the essential nutrient required for normal cell growth and development, which plays critical roles in many biological processes, such as blood formation and functioning of various enzymes. Moreover, as well as its deficiency, Cu2+ overload can result in a variety of diseases, such as parkinson’s disease, epileptic seizures, renal and liver damage.4 Therefore, the development of new fluorescent probes for the determination of Hg2+ or Cu2+ is highly desirable. Up to now, many fluorescent probes for Hg2+ or Cu2+ were reported in recent literature.5,6 However, some of the reported fluorescent probes for Hg2+ or Cu2+ can be used only in organic medium or organic-containing solution, which limits their practical application.7 Even then, some of the reported fluorescent probes sometimes suffer from the intricate synthetic procedures.8 Therefore, there is a great need for the construction of new fluorescent probes that can detect Hg2+ or Cu2+ in aqueous solution by a simple synthetic approach. In recent years, the construction of multi-ion responsive fluorescent probes with multiple emission modes received immense interest.9 Fluorescent probes with a differential response towards multiple analytes are cost-effective and highly desirable for real-time applications. Moreover, such kind of fluorescent probes are indispensable for designing molecular logic gates and This journal is © The Royal Society of Chemistry [year]
50
55
60
65
70
molecular keypad lock devices.10 However, to the best of our knowledge, just two examples of bifunctional fluorescent probes capable of the simultaneous detection of Hg2+ and Cu2+ have been reported.11 For example, Yin and co-workers reported a bifunctional probe that can recognize Hg2+ and Cu2+ only in organic solvent (CH3CN).11a Tian and Zhu reported another bifunctional probe DCPP.11b Although its sensing properties could be investigated in organic-containing solution (containing 60% CH3CN as a co-solvent), DCPP displayed a relatively low sensitivity. The addition of five equivalents of Hg2+ to the solution of DCPP just induced 2.2-fold enhancement of the fluorescence intensity. Thus, it is still a challenge to develop bifunctional fluorescent probes for Hg2+ and Cu2+ in aqueous solution with high selectivity and sensitivity. Recently, we have reported a highly sensitive and selective naphthalimide-based Ag+ fluorescent probe NPQ, which contains a hydroxyquinoline moiety as part of the receptor.12 Herein, by the replacement of hydroxyquinoline moiety in NPQ with morpholine moiety, a novel fluorescent probe NPM was synthesized. Interestingly, NPM exhibited selective fluorescence turn-on response toward Hg2+ and selective fluorescence turn-off to Cu2+ in aqueous solution. With the aim to obtaining the insight into the possible sensing mechanisms and binding modes of
Scheme 1 The structures of fluorescent probes of NPQ, NPM and model compounds NBM and NPP.
[journal], [year], [vol], 00–00 | 1
Dalton Transactions Accepted Manuscript
Published on 18 March 2014. Downloaded by National Dong Hwa University Library on 29/03/2014 08:21:22.
www.rsc.org/xxxxxx
Page 3 of 7
Dalton Transactions View Article Online
DOI: 10.1039/C4DT00014E
600 O
piperazine
Cl X
200 2+
100
Wavelength (nm)
NPM with Hg and Cu , two model compounds (NBM and NPP) were designed and synthesized as shown in Scheme 1. 5
Results and discussion
10
45
pH effect of NPM
15
20
25
30
35
40
The absorption and emissive properties of NPM on changing the pH were determined as shown in Fig. S1. A slight change in the absorption spectra of NPM was observed when the pH>7.0. However, when the pH
