A rhodamine–benzothiazole conjugated sensor for colorimetric, ratiometric and sequential recognition of copper(II) and sulfide in aqueous media

doi:10.1016/j.saa.2014.12.055

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Volume 139, 15 March 2015, Pages 329-334

https://doi.org/10.1016/j.saa.2014.12.055 Get rights and content

Highlights

•
A new rhodamine–benzothiazole conjugated sensor was synthesized.
•
Sequential recognition to Cu²⁺ and S²⁻ in neutral aqueous solution.
•
Ratiometric chromogenic recognition of Cu²⁺ and S²⁻.
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The Cu²⁺ and S²⁻ recognition are highly selective and sensitive.

Abstract

A new rhodamine–benzothiazole conjugated colorimetric sensor 1 that exhibits sequential recognition to Cu²⁺ and S²⁻ in CH₃CN/HEPES buffer (v/v = 1:1, HEPES 10 mM, pH = 7.0) solution has been developed. Sensor 1 displays highly selective and sensitive recognition to Cu²⁺ with a ratiometric behavior, and the resultant 1-Cu²⁺ complex can act as a highly selective S²⁻ sensor via Cu²⁺ displacement approach. The Cu²⁺ and S²⁻ recognition processes are rapid and reversible, and the Cu²⁺ and S²⁻ inputs can result in an INHIBIT logic gate.

Graphical abstract

A new rhodamine–benzothiazole conjugated colorimetric sensor 1 that exhibits sequential recognition to Cu²⁺ and S²⁻ in CH₃CN/HEPES buffer (v/v = 1:1, pH = 7.0) solution has been developed.

Introduction

The development of artificial receptors for the sensing and recognition of environmentally and biologically important ionic species, especially transition metal ions, is currently of great interest [1]. Copper, as the third most abundant transition metal in the human body, is vital for both environmental and biological systems [2], [3]. Nevertheless, at high concentrations, copper becomes a toxic and hazardous elements to organisms such as leading to gastrointestinal disturbance and the damage to the liver and kidneys [4], [5].

Also, in recent years, the detection of anions gains more and more concerns. As one of the biologically and environmentally important anions [6], sulfide anions are widely generated as a byproduct in industrial processes, for instance, conversion into sulfur, preparation of sulfuric acid and dyes, cosmetic manufacturing, production of wood pulp, etc. [7], [8], [9]. Although sulfide has many industrial utilities, exposure to high levels of sulfide can lead to various physiological and biochemical problems including irritation in mucous membranes, unconsciousness, and respiratory paralysis [10]. Therefore, sulfide detection has received immense interest and a number of sulfide selective probes based on irreversible sulfide-specific triggered reactions have been reported [11], [12], [13]. Nevertheless, most of the organic reactions were time-consuming and required relatively strict conditions, which limited the application of the probes. Development of chemosensors based on metal ion displacement (especially utilizing a Cu²⁺ affinity) has been proved to be an effective method to realize real-time and reversible sulfide detection [14], [15], [16].

Recently, we reported some simple and selective fluorescent and colorimetric sensors for relay recognition of Cu²⁺ and S²⁻ ions [17], [18]. However, most of the works depend on fluorescence signal “on–off” switching at the same position, which usually suffer from the interferences of environmental conditions and are prone to hamper their accuracy detection. Utilization of ratiometric chemosensor is an effective method to hurdle this issue due to the built-in correction property of ratiometric sensors [19]. Rhodamine chromophore has been widely employed to construct sensors for naked eye observable sensing of metal ions due to its well-known spirolactam to ring-opened amide equilibrium [20], [21], [22], [23]. Incorporation of a chromophore with metal ion binding sites into rhodamine moiety is a good approach to construct ratiometric and colorimetric metal ion sensors.

Herein, we designed and synthesized a new rhodamine–benzothiazole conjugated chemosensor 1, which exhibits a rapid, selective, sensitive and reversible recognition to Cu(II) via ratiometric UV–vis absorption changes in neutral buffered media [24], [25]. Moreover, the on-site generated 1-Cu²⁺ complex displays highly selective and sensitive recognition to S²⁻. Thus, a colorimetric and ratiometric sequential recognition of Cu²⁺ and S²⁻ has been achieved.

Section snippets

Materials and instruments

Unless otherwise stated, solvents and reagents were purchased as analytical grade and used without further purification. Ethanol was freshly distilled from Magnesium powder and Iodine grain. Doubly distilled water was used for spectral detection. Compounds 2 [26] and 4 [27] were prepared according to literature methods, respectively. ¹H NMR and ¹³C NMR spectra were recorded on Agilent 400-MR spectrometer. Low-resolution mass spectroscopy (LRMS) was measured on an Agilent 1100 series LC/MSD mass

Colorimetric recognition of 1 to Cu²⁺

Sensor 1 was synthesized by the method depicted in Scheme 1. The rhodamine B spirolactam moiety was selected as potential signaling unit to sense Cu²⁺, which was envisioned to turn-on the visible color when it bound to Cu²⁺ [28]. On the other hand, the benzothiazole moiety introduced to sensor 1 with the hypothesis that Cu²⁺ binding will interrupt the original absorption property of benzothiazole skeleton.

The UV–vis absorption property of probe 1 (10 μM) in CH₃CN/HEPES buffer (v/v = 1:1, pH = 7.0)

Conclusions

In summary, a new rhodamine–benzothiazole conjugated colorimetric sensor 1 has been designed and synthesized. Sensor 1 displays highly selective, sensitive and ratiometric recognition to Cu²⁺ in CH₃CN/HEPES buffer (v/v = 1:1, pH = 7.0) solution. The in situ generated 1-Cu²⁺ complex behaves as a S²⁻ sensor with high sensitivity and selectivity through metal ion displacement approach. Both the Cu²⁺ and S²⁻ recognition processes are rapid and reversible, and the Cu²⁺ and S²⁻ inputs exhibit an INHIBIT

Acknowledgments

We are grateful to the National Natural Science Foundation of China (No. 21176029, 21476029), the Natural Science Foundation of Liaoning Province of China (No. 20102004) and the Program for Liaoning Excellent Talents in University (LJQ2012096) for financial support.

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Rhodamine-based photoresponsive sensors have emerged as a focal point in the realm of chemical sensing, garnering substantial attention owing to their exceptional sensitivity, straightforward implementation, and real-time detection capabilities across diverse analytes. Within this class, a notable substituent stands out for its well-established reputation, characterized by its electron-donating prowess and customizable coordination cavity, resulting in a heightened sensitivity towards various metal ions. The comprehensive examination of these sensors in the review centers on key parameters such as the detection target, detection limit, detection solution system, and detection method. Notably, the inclusion of an array of metal ions in the discussion contributes to the versatility of these sensors. To enhance the readability and applicability of the review, a detailed exploration of the indirect sensing strategy is presented, showcasing its efficacy in achieving sensitive detection, especially for anions and other species. This strategic approach not only broadens the scope of application but also underscores the versatility of rhodamine-based sensors, making this review a valuable resource for researchers and practitioners in the field of chemical sensing.
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A simple ratiometric, turn-on chromo-fluorogenic sensor, (E)-2-((2-hydroxybenzylidiene) amino)-5-nitrophenol (HBAN), has been developed, synthesized, and characterized by several conventional analytical methods. HBAN is found to be selective for the sequential detection of Al³⁺ ions and picric acid (PA), respectively, based on the fluorescence ‘off-on-off’ method. A remarkable fluorescence enhancement of HBAN is detected at 540 nm upon binding with Al³⁺ ions with a visual yellow color fluorescence under a portable 365 nm UV light irradiation. Among the various tested nitroaromatic compounds, PA selectively quenches the fluorescence of the Al³⁺ ions chelated HBAN complex. The formation of the complex between HBAN and Al³⁺ ions is found to be in a 1:1 stoichiometric ratio, and the LOD is found to be nanomolar range. The mechanistic aspects of detecting Al³⁺ ions have been elucidated by different spectroscopic and density functional theoretical analyses. Additionally, a test kit based on paper strips coated with HBAN is demonstrated to selectively detect Al³⁺ ions.
Small molecule sensors for the colorimetric detection of Copper(II): A review of the literature from 2010 to 2022
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Small molecules can display certain electronic and structural features that enable their use for metal-sensing applications in different fields. Of the reported metal sensors, there has been increasing interest in copper sensing in the past decade, given the biological importance of copper as well as its presence as a potential contaminant in water and fuels. Molecules used for copper(II) sensing generally consist of a fluorophore/chromophore and a ligand for selective metal ion recognition. This review article focuses on literature contributions since the year 2010 concerning small molecule copper(II) sensors that provide a naked-eye color response in solution. We present molecular structural features and sensing mechanisms for the colorimetric and fluorometric detection of copper(II) ions in different environmental, agricultural, and biological samples. In addition, the sensing performance of these chemosensors is compared and discussed, which could aid in the future design of chemosensors for copper(II). Finally, we outline the challenges and future prospects of fluorophore/chromophore–ligand chemistry in applications of small molecules for fluorometric and colorimetric assays of copper(II).
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Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Materials and instruments

Colorimetric recognition of 1 to Cu²⁺

Conclusions

Acknowledgments

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Cited by (54)

Review of current developments in rhodamine derivatives-based photoresponsive chemosensors for ion detection

Nanomolar level colorimetric and On–Off fluorimetric sensing of Cu<sup>2+</sup>: Theoretical, Smartphone, test kit and food application outcomes

A ratiometric, turn-on chromo-fluorogenic sensor for sequential detection of aluminium ions and picric acid

Small molecule sensors for the colorimetric detection of Copper(II): A review of the literature from 2010 to 2022

Synchronous colorimetric determination of CN<sup>−</sup>, F<sup>−</sup>, and H<inf>2</inf>PO<inf>4</inf><sup>−</sup> based on structural manipulation of hydrazone sensors

Rigid anthraquinone based sensor for dual and differential colorimetric detection of Cu<sup>2+</sup> and Ni<sup>2+</sup> ions: Mimicking different molecular logic systems

A rhodamine–benzothiazole conjugated sensor for colorimetric, ratiometric and sequential recognition of copper(II) and sulfide in aqueous media

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Materials and instruments

Colorimetric recognition of 1 to Cu2+

Conclusions

Acknowledgments

Bioorg. Med. Chem. Lett.

Biochem. Pharmacol.

Dyes Pigm.

Sens. Actuators B: Chem.

Inorg. Chem. Commun.

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Polyhedron

Dyes Pigm.

Dyes Pigm.

Sens. Actuators B: Chem.

Chem. Rev.

J. Neurol.

Chem. Rev.

Chem. Rev.

Org. Lett.

J. Am. Chem. Soc.

Angew. Chem. Int. Ed.

Org. Lett.

Colorimetric recognition of 1 to Cu²⁺