Physicochemical studies of chemosensor imidazole derivatives: DFT based ESIPT process

Area of Science:

• Organic Chemistry
• Photochemistry
• Computational Chemistry

Background:

• Imidazole derivatives are versatile scaffolds in medicinal chemistry and materials science.
• Understanding excited-state intramolecular proton transfer (ESIPT) is crucial for designing fluorescent probes.
• Solvent-free synthesis offers environmental and economic advantages.

Purpose of the Study:

• To synthesize novel substituted imidazole derivatives efficiently.
• To investigate the photophysical properties, particularly ESIPT, of these compounds.
• To explore their potential as chemosensors for transition metal ions.

Main Methods:

• Solvent-free synthesis catalyzed by molecular iodine.
• Emission spectroscopy for studying ESIPT.
• Density Functional Theory (DFT) calculations for electronic structure and potential energy surfaces (PES).
• Molecular Electrostatic Potential (MEP) surface analysis.

Main Results:

• High yields of substituted imidazoles achieved under solvent-free conditions.
• ESIPT process observed and characterized in hydroxy imidazole derivatives.
• DFT calculations provided insights into ground and excited states, rotamer interconversion barriers, and charge distributions.
• MEP analysis indicated high electron density at N(3) nitrogen.
• Fluorescence enhancement observed in the presence of transition metal ions, attributed to suppressed radiationless decay.

Conclusions:

• Efficient synthesis of imidazole derivatives is feasible via solvent-free, iodine-catalyzed reactions.
• The synthesized compounds exhibit interesting photophysical properties, including ESIPT.
• DFT calculations effectively elucidate the electronic and structural features governing their behavior.
• The observed fluorescence enhancement suggests promising applications as chemosensors for detecting transition metal ions.