A highly selective colorimetric and “turn-on” fluorimetric chemosensor for detecting CN based on unsymmetrical azine derivatives in aqueous media

https://doi.org/10.1016/j.saa.2016.05.017Get rights and content

Highlights

  • Chemosensor S1 was designed with ease of synthesis.

  • Sensor S1 demonstrates specifically selective fluorescence recognition to CN.

  • Receptor S1 shows highly selective colorimetric response for CN.

  • The probe S1 responds with CN in aqueous solution system.

  • Test strips of S1 were prepared and convenient and rapidly detected CN.

Abstract

A novel highly selective chemosensor S1 for cyanide based on unsymmetrical azine derivative was successfully designed and synthesized, which showed both colorimetric and fluorescence turn-on responses for cyanide ions in aqueous. This structurally simple chemosensor could detect CN anion over other anions in aqueous solution DMSO/H2O (v/v = 3:2) undergo deprotonation reaction. Results showed that the chemosensor S1 exhibited 50 fold enhancement in fluorescence at 530 nm and showed an obvious change in color from colorless to yellow that could be detected by naked eye under the UV-lamp after the addition of CN in aqueous solution. Moreover, the detection limit on fluorescence response of the sensor to CN is down to 6.17 × 10 8 M by titration method. Test strips based on S1 were obtain, which could be used as a convenient and efficient CN test kit to detect CN in aqueous solution.

Graphical abstract

A simple cyanide highly selective and sensitive fluorescent enhanced chemosensor S1 based on unsymmetrical azine derivatives had been designed and synthesized.

Image 1
  1. Download : Download high-res image (101KB)
  2. Download : Download full-size image

Introduction

Cyanide is highly toxic to humans and almost all other forms of life [1], [2]. A significant proportion of victims among fire victims is due to cyanide poisoning, as blood cyanide concentrations reach a level of 23–26 μM [3], [4]. Despite cyanide toxicity, large quantities of cyanide salts are widely used in synthetic fibers, resins, herbicides, and the gold-extraction process [5]. The Environmental Protection Agency (EPA) has set the MCL (MCL: maximum contaminant level) of 1.9 × 10 6 M for cyanide in order to regulate safe levels for drinking water systems [6]. Rapid and accurate determination of cyanide would facilitate forensic investigation, medical diagnosis, and chronic cyanide monitoring. In this regard, chemosensor can be an important material to monitor these anions [7]. In addition, chemosensor can be simple and convenient with showing its optical change. [8], [9] However, many kinds of colorimetric or fluorometric CN selective receptors have been researched in organic media. Actually, in biological and environmental systems, anion-receptor interactions commonly occur in aqueous media [10]. Most of them suffer the severely interference from coexisting anions such as F, AcO, and H2PO4. Few of them exhibit spectral changes in both absorption and emission spectra [11], [12]. Therefore, the design of colorimetric and fluorimetric sensors for CN in aqueous media is therefore currently the focus of attention.

Azines are attracting the increasing interests for their potential in medical, biological due to their antimicrobial, antibacterial activity [13]. In acyclic chemistry, the products of the reaction between one molecule hydrazine hydrate and two molecules of carbonyl compounds are called azines, among which the symmetrical compounds are widely applied [14]. In the aspect of recognition, numerous works devoted to studying structure of Schiff base complexes, however, the fluorescence properties of azines currently has yet to see the detailed report [15], [16]. As a matter, azine moieties, N-N linked diimines, are very tolerant to hydrolysis and have good ligating ability [17]. Sheng et al. have reported a symmetrical azine chemosensor for Hg2 +, but for anion this kind of compound currently has yet to see the detailed report [18], [19] (Fig. S6).

We have synthesized a new asymmetrical azine chemosensor S1 synthesized with diphenyl diketone and salicylaldehyde hydrazone by one step (Scheme 1). This is a Chromo-fluorogenic anion receptor, which shows fluorescence and UV–vis spectra selectivity for CN in DMSO/H2O (v/v = 3:2) binary solution over other anions. Chemosensor S1 could form a fine conjugate structure with azine moiety, as a result, the chemosensor has an excellent optical property to achieve naked-eye colorimetric and fluorimetric recognition. Meanwhile, salicylicaldehyde hydrazone provided an active hydrogen atom, which easily combined with strong alkaline ion CN and allowed the receptors to tolerate a substantial amount of water from the solvent [20]. When CN was added to the sensor solution, solution color changes from colorless to yellow and shows strong yellow fluorescence. According to the data, this was a deprotonation type reaction based for cyanide ion detection at room temperature. The detection limit in fluorescence response of the sensor to CN was down to 6.17 × 10 8 M. And the mechanism of this process was verified by spectroscopic methods including 1H NMR, UV–vis, and mass spectrometry.

Section snippets

Materials and physical methods

All reagents were purchased from commercial supplies and used without further purification. Solvents and twice-distilled water were purified by standard methods. Fresh double distilled water was used throughout the experiment. All the tetrabutylammonium salts, salicylicaldehyde hydrazone, and diphenyl diketone were purchased from Alfa–Aesar Chemical Reagent Co, and stored in a vacuum desiccator. Chemical shifts are reported in ppm downfield from tetramethylsilane (TMS, δ scale with solvent

Results and discussion

A series of host-guest recognition experiments were performed to investigate the CN recognition ability of the S1 in aqueous solution. The colorimetric and fluorimetric sensing abilities were mainly investigated by adding pure water with various anions to the DMSO/H2O (v/v = 3:2). In the UV–vis spectrum of a solution of S1 in DMSO (2.0 × 10 5 M), the strong and broad absorption at 355 nm disappeared, and at 425 nm a new absorption appeared when 50 equiv. CN were added (Fig. 2). No significant UV–vis

Application

To facilitate the use of S1 for the detection of cyanide, test strips were prepared by immersing filter papers into a DMSO/H2O (v/v = 3:2) binary solution of S1 (0.01 M) followed by its exposure to air for drying. As shown in the Fig. 9, interestingly, the fluorescence color changed immediately from blue to purple on the test papers were immersed into an aqueous solution (5 mM) of cyanide under UV irradiation. Hence, the test strips could conveniently detect CN in solutions.

Conclusion

In conclusion, we have presented an efficient and simple chemosensor S1, which showed special selectivity and high sensitivity UV–vis absorption and fluorescence recognition for CN in DMSO/H2O (v/v = 3:2) solutions. Moreover, the detection limit on fluorescence response of the sensor to CN is down to 6.17 × 10 8 M. This sensing system shows many advantages. We believe that these characteristics of S1 make it attractive for further molecular modifications and underlying applications as a

Acknowledgment

This work was supported by the National Nature Science Foundation of China (no. 21467012).

References (21)

  • H.M. Nie et al.

    Dyes Pigments

    (2014)
    Y. Sun et al.

    Talanta

    (2009)
    L. Deng et al.

    Anal. Chem.

    (2010)
  • E. Zeynep et al.

    Org. Lett.

    (2008)
    K.W. Kulig

    Cyanide Toxicity

    (1991)
    P. Singh et al.

    J. Fluoresc.

    (2014)
  • B. Sun et al.

    Water Res.

    (1998)
    M. Shahid et al.

    Tetrahedron

    (2012)
  • Z.P. Liu et al.

    J. Organomet. Chem.

    (2011)
    T. Anand et al.

    Anal. Chim. Acta

    (2015)
    C. Arivazhagan et al.

    Dalton Trans.

    (2016)
  • K. Karaoglu et al.

    J. Organomet. Chem.

    (2015)
  • R.L. Sheng et al.

    Sensors Actuators B

    (2008)
  • Y. Liu et al.

    Supramol. Chem.

    (2001)
  • M.A. Holland et al.

    Clin. Pharm.

    (1986)
    H. Khajehsharifi et al.

    Sensors Actuators B

    (2015)
  • X. Zhou et al.

    Adv.

    (2013)
    J.H. Hu et al.

    J. Chem. Res.

    (2012)
    X. Liu et al.

    New J. Chem.

    (2014)
  • I. Jalal et al.

    Adv.

    (2013)
    P.M. Emilio et al.

    Adv. Funct. Mater.

    (2006)
There are more references available in the full text version of this article.

Cited by (0)

View full text