A ditopic colorimetric sensor for fluoride ion based on thiourea mercury complex
Mei-Zhen Sun1, Fang-Ying Wu, Yu-Mei Wu
1Department of Chemistry and Center of Analysis and Testing, Nanchang University, Nanchang 330031, China.
Summary
A new sensor detects fluoride ions with high selectivity and sensitivity. This chromogenic receptor allows for simple, color-based detection of fluoride in solutions.
Area of Science:
- Analytical Chemistry
- Supramolecular Chemistry
- Sensing Technology
Background:
- Development of selective anion sensors is crucial for environmental and biological monitoring.
- Chromogenic receptors offer visual detection methods, simplifying analysis.
- Mercury(II) complexes are explored for their unique sensing properties.
Purpose of the Study:
- To synthesize a novel ditopic chromogenic receptor for anion detection.
- To investigate the sensing capabilities of the synthesized receptor with metal ions.
- To develop a colorimetric assay for fluoride ion detection.
Main Methods:
- Synthesis of N-5-(8-hydroxy)quinoline-N'-4'-nitro-phenyl thiourea (1).
- Formation of the metal complex 1-Hg(2+).
- Spectrophotometric analysis of the complex's response to various anions, particularly fluoride.
Main Results:
- The 1-Hg(2+) complex exhibited high sensitivity and selectivity for fluoride ions over other tested anions.
- Formation of the 1-Hg(2+)-F(-) complex induced intramolecular charge transfer, causing a distinct color change from colorless to red.
- A linear response for fluoride was observed in the concentration range of 8.0 x 10(-6) to 2.0 x 10(-5) mol L(-1) with a limit of detection (LOD) of 1.4 x 10(-6) mol L(-1).
Conclusions:
- A novel chromogenic receptor was successfully synthesized and complexed with Hg(2+).
- The developed sensor provides a rapid, visual, and selective method for fluoride detection in acetonitrile.
- The sensor demonstrates potential for practical applications in fluoride ion analysis.
Related Concept Videos
00:39Complexometric Titration: Overview
Complexometric titration involves the formation of a complex by reacting a metal ion with one or more ligands. A visual indicator often detects the end point of a complexometric titration. It is added to the metal solution before the titration, forming a stable metal–indicator complex and imparting color to the solution. As the titration approaches the equivalence point, the excess of the added ligand displaces the indicator from the metal–indicator complex, releasing the free indicator. The...
01:25Fluorescence and Phosphorescence: Instrumentation
Fluorometers and spectrofluorometers are two types of instruments used for measuring molecular fluorescence. These instruments differ in how they select excitation and emission wavelengths and the type of light sources they utilize. Fluorometers use absorption interference filters to choose excitation and emission wavelengths. The excitation source in a fluorometer is typically a low-pressure mercury vapor lamp that emits intense lines distributed throughout the ultraviolet and visible regions.
01:19Precipitation Titration: Endpoint Detection Methods
In argentometric precipitation titrations, endpoints can be detected visually by the Mohr, Volhard, and Fajans methods. In the Mohr method, adding a soluble chromate indicator gives an initial yellow color to the analyte solution. As the titrant is added, the first excess of silver ions forms a red silver chromate precipitate, marking the endpoint. The solution pH should be maintained at about 8 by adding solid CaCO3.
In the Volhard method, a standard excess of AgNO3 is first added to the...
In the Volhard method, a standard excess of AgNO3 is first added to the...
01:13Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are difficult to achieve. Fluorine is so reactive that its reaction with benzene is difficult to control, resulting in poor yields of monofluoroaromatic products. To address this, Selectfluor reagent is used as a fluorine source in which a fluorine atom is bonded to a positively charged nitrogen.
02:39Indicators
Certain organic substances change color in dilute solution when the hydronium ion concentration reaches a particular value. For example, phenolphthalein is a colorless substance in any aqueous solution with a hydronium ion concentration greater than 5.0 × 10−9 M (pH < 8.3). In more basic solutions where the hydronium ion concentration is less than 5.0 × 10−9 M (pH > 8.3), it is red or pink. Substances such as phenolphthalein, which can be used to determine the pH of a solution, are called...
01:14Photoluminescence: Applications
Photoluminescence offers a wide range of applications due to its inherent sensitivity and selectivity. This technique allows for both direct and indirect analyses of the analyte. Direct quantitative analysis is possible when the analyte exhibits a favorable quantum yield for fluorescence or phosphorescence. However, an indirect analysis may be feasible if the analyte is not fluorescent or phosphorescent, or if the quantum yield is unfavorable. Indirect methods include reacting the analyte with...