A Quick, Highly Selective and Sensitive Colorimetric and Fluorimetric Sensor for Cyanide Ion

Area of Science:

• Chemical Sensors
• Analytical Chemistry
• Organic Synthesis

Background:

• Cyanide is a highly toxic pollutant requiring sensitive detection methods.
• Existing cyanide sensors may lack selectivity or sensitivity for real-world applications.

Purpose of the Study:

• To develop and characterize a novel diindolium-based sensor (DI) for selective and sensitive cyanide ion detection.
• To investigate the sensing mechanism and assess the sensor's performance against established safety limits.

Main Methods:

• Synthesis of the diindolium moiety.
• Spectroscopic analysis including NMR and HRMS for structural confirmation.
• UV-visible and fluorescence spectroscopy for sensing studies.
• Selectivity tests with various interfering anions.
• Determination of detection limits and application in water samples.

Main Results:

• The diindolium sensor (DI) exhibited a distinct color change from pink to colorless upon interaction with cyanide ions (CN⁻).
• A fluorescence shift from orange to light blue was observed under UV irradiation.
• The sensor demonstrated high selectivity and sensitivity, with detection limits below WHO guidelines (1.4 × 10⁻⁷ M via UV-Vis, 8.2 × 10⁻⁸ M via fluorescence).
• The sensing mechanism involves nucleophilic addition of CN⁻ to the indolium core.

Conclusions:

• The newly synthesized diindolium sensor (DI) offers a simple, visual, and sensitive method for detecting cyanide ions.
• Its high selectivity and low detection limits make it suitable for environmental monitoring and water quality assessment.
• The sensor's performance indicates potential for practical applications in cyanide testing kits.