Supramolecular Rings as Building Blocks for Stimuli-Responsive Materials

Area of Science:

• Materials Science
• Polymer Chemistry
• Supramolecular Chemistry

Background:

• Stimuli-responsive polymers are crucial for translating environmental changes into material responses.
• Incorporating optically active molecules into polymers offers a pathway to achieve this responsiveness.
• Benzothiadiazole emitters and naphthalene diimide quenchers are promising optically active molecules.

Purpose of the Study:

• To design and synthesize novel sensor molecules based on benzothiadiazole and naphthalene diimide.
• To investigate the self-assembly and photophysical properties of these sensor molecules.
• To incorporate these sensors into a polyurethane matrix and evaluate their stimuli-responsive behavior.

Main Methods:

• Synthesis of donor-acceptor sensor molecules with varying spacers.
• Spectroscopic studies (UV-Vis absorption, fluorescence spectroscopy) in solution.
• Incorporation of sensor molecules into a polyurethane host.
• Optical characterization of the polymer in solid and solvent-swollen states.

Main Results:

• Sensor molecules self-assembled into cyclic structures, quenching fluorescence by up to 43%.
• Donor/acceptor interactions were sensitive to solvent polarity and ion concentration.
• The sensor molecule, when incorporated into polyurethane, exhibited stimulus-induced dye pairing.
• A solvatochromic quenching effect was observed in solvent-swollen polymers, shifting emission color from green to yellow.

Conclusions:

• Novel sensor molecules with tunable optical properties were developed.
• These molecules demonstrate stimuli-responsive behavior in solution and within a polymer matrix.
• The findings pave the way for developing advanced optical sensor materials for environmental monitoring.