New Styryl 1,3,4-Oxadiazol-Based Fluorometric "Turn on" pH Sensor

Area of Science:

• Organic Chemistry
• Analytical Chemistry
• Materials Science

Background:

• Development of selective chemical sensors is crucial for various analytical applications.
• Existing pH sensors often lack specificity, responding to a broad range of pH values.
• 1,3,4-oxadiazole derivatives offer a promising scaffold for designing novel functional materials.

Purpose of the Study:

• To synthesize and characterize a new 1,3,4-oxadiazole derivative, MeO-SODA.
• To investigate the pH sensing capabilities of MeO-SODA, particularly at extremely acidic levels.
• To explore the potential practical applications of this new chemical probe.

Main Methods:

• Synthesis of the 1,3,4-oxadiazole derivative (MeO-SODA).
• Full characterization using Infrared (IR), Nuclear Magnetic Resonance (NMR), and High-Resolution Mass Spectrometry (HRMS).
• Solvatochromic studies in ten different solvents.
• Absorption and fluorescence measurements across a range of pH values (pH 2-12).

Main Results:

• MeO-SODA exhibited non-radiative transitions influenced by solvent hydrogen bonding capacity.
• Fluorescence emission was exclusively observed at pH 2, indicating high selectivity.
• Successful detection of acidity in lemon juice demonstrated practical applicability.

Conclusions:

• MeO-SODA functions as a highly selective fluorescent sensor for extremely acidic environments (pH 2).
• The probe's behavior is influenced by solvent properties, offering insights into molecular design.
• This study paves the way for developing new probes with single-pH detection capabilities.