Azocalix[4]arene strapped calix[4]pyrrole: a confirmable fluoride sensor

Area of Science:

• Supramolecular Chemistry
• Analytical Chemistry
• Sensing Technology

Background:

• Development of selective chemosensors is crucial for environmental and biological monitoring.
• Calix[4]arene derivatives offer versatile platforms for molecular recognition.
• Chromogenic sensing provides a visual and rapid detection method.

Purpose of the Study:

• To design and synthesize a novel chromogenic sensor for ion detection.
• To investigate the selectivity of the sensor towards fluoride ions.
• To establish a method for highly specific fluoride sensing in complex matrices.

Main Methods:

• Synthesis of 1,3-di-p-nitrophenylazocalix[4]arene-calix[4]pyrrole (probe 1).
• Spectrophotometric analysis of probe 1's response to various anions (F(-), CH(3)CO(2)(-), PhCO(2)(-), H(2)PO(4)(-)).
• Investigation of the effect of calcium ions (Ca(2+)) on the sensing mechanism.

Main Results:

• Probe 1 displayed color changes upon interaction with F(-), CH(3)CO(2)(-), PhCO(2)(-), and H(2)PO(4)(-).
• The sensor showed initial cross-reactivity with acetate, benzoate, and phosphate ions.
• Addition of Ca(2+) ions enabled highly specific detection of F(-) by reverting the color from light sky blue to light orange.

Conclusions:

• A new chromogenic sensor based on a calix[4]arene-calix[4]pyrrole hybrid was successfully synthesized.
• The sensor demonstrates potential for selective fluoride detection through a Ca(2+)-assisted mechanism.
• This approach offers a visual and sensitive method for identifying fluoride ions.