A fluoride-selective PCT chemosensor based on formation of a static pyrene excimer

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Analytical Chemistry

Background:

• Calixarene derivatives are widely used as host molecules in supramolecular chemistry.
• Fluorescent chemosensors offer sensitive and selective detection of analytes.
• Pyrene-based fluorophores are known for their distinct photophysical properties, including excimer formation.

Purpose of the Study:

• To synthesize and characterize a novel calixarene-based fluorescent chemosensor.
• To investigate the complexation behavior of the sensor with fluoride ions (F⁻).
• To explore the photophysical changes upon fluoride binding for sensing applications.

Main Methods:

• Synthesis of calixarene derivative 1 incorporating two pyrene units.
• Spectroscopic analysis (absorption and fluorescence) of the sensor in the presence of varying fluoride concentrations.
• Characterization of spectral shifts and fluorescence intensity changes.

Main Results:

• Successful synthesis of calixarene-based fluorescent chemosensor 1.
• Complexation with F⁻ caused a red shift in absorption (Δλ = 54 nm to 400 nm).
• Fluoride binding induced a blue shift in excimer emission (Δλ = 12 nm to 470 nm) with enhanced fluorescence intensity, attributed to static excimer formation.

Conclusions:

• The synthesized calixarene derivative functions as an effective fluorescent chemosensor for fluoride ions.
• The observed spectral changes provide a basis for sensitive and selective fluoride detection.
• The formation of a ground-state pyrene dimer (static excimer) is crucial for the sensing mechanism.