Fluorescent Molecular Rotors Based on Hinged Anthracene Carboxyimides

Area of Science:

• Chemistry
• Materials Science
• Biophysics

Background:

• Temperature and viscosity are critical in various scientific fields.
• Direct relationships between temperature, viscosity, and fluorescent sensors are under-explored.
• Fluorescent molecular rotors are sensitive to their microenvironment.

Purpose of the Study:

• To design and synthesize novel anthracene carboxyimide-based fluorescent molecular rotors.
• To investigate the photophysical properties of these rotors in different solvents and viscosity conditions.
• To establish correlations between rotor fluorescence, viscosity, and temperature.

Main Methods:

• Synthesis of three anthracene carboxyimide-based fluorescent molecular rotors (1DiAC∙Cl, 2DiAC∙Cl, 9DiAC∙Cl).
• Photophysical characterization in various solvents (e.g., DMF, ethanol, water) to study solvatochromism.
• Analysis using Lippert-Mataga, Kamlet-Taft, and Catalán parameters.
• Viscosity-dependent studies using water-glycerol mixtures and temperature variations.

Main Results:

• Solvent polarizability induced solvatochromism, with red-shifted spectra due to torsion angles.
• Rotors exhibited enhanced fluorescence in high-viscosity media due to restricted intramolecular rotation.
• Two rotors (2DiAC∙Cl, 9DiAC∙Cl) showed linear correlations between fluorescence intensity and viscosity.
• All three rotors displayed exponential regression between emission intensity and viscosity-related temperature.

Conclusions:

• The synthesized molecular rotors are sensitive to environmental viscosity and temperature.
• These rotors demonstrate potential as fluorescent sensors for viscosity and temperature.
• The findings contribute to the development of smart materials and advanced sensing technologies.