Benzothiazole integrated into a cryptand for ESIPT-based selective chemosensor for Zn²⁺ ions

Area of Science:

• Supramolecular Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Excited state intramolecular proton transfer (ESIPT) is a photophysical process sensitive to environmental changes.
• Developing selective and sensitive fluorescent probes for metal ion detection is crucial for environmental and biological monitoring.
• Benzothiazole derivatives are known for their versatile photophysical properties.

Purpose of the Study:

• To design and synthesize a novel benzothiazole-based cryptand.
• To investigate its fluorescence response to metal ions, particularly Zn²⁺.
• To evaluate the probe's selectivity, sensitivity, and potential for environmental applications.

Main Methods:

• Chemical synthesis of the benzothiazole-based cryptand.
• Spectroscopic characterization (NMR, Mass Spectrometry, X-ray Crystallography).
• Fluorescence spectroscopy to study metal ion interactions and sensing mechanism (ESIPT inhibition).

Main Results:

• Successful synthesis and structural confirmation of the novel cryptand.
• High fluorescence enhancement observed in the presence of Zn²⁺ ions.
• Demonstrated high selectivity for Zn²⁺ over other metal ions and anions.
• Achieved a low detection limit of 0.20 μM for Zn²⁺, meeting EPA standards.

Conclusions:

• The designed benzothiazole-based cryptand acts as an effective fluorescent sensor for Zn²⁺.
• The sensing mechanism relies on the inhibition of the ESIPT process via Zn²⁺ chelation.
• The probe's high selectivity and sensitivity make it suitable for environmental monitoring of zinc.