Dynamic Molecular Crystal Triggered by Near-Ambient Intramolecular Twisting for Switchable Luminescence and...

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Organic Electronics

Background:

• Dynamic molecular crystals are crucial for applications requiring mild operating conditions.
• Designing intramolecular twisting for reversible transitions near ambient temperatures remains a significant challenge.

Purpose of the Study:

• To fabricate dynamic rod-shaped crystals with tunable optical properties.
• To investigate the mechanism of reversible thermofluorochromism induced by mild thermal stimulation.

Main Methods:

• Synthesis of donor-acceptor-donor molecular architecture.
• Characterization using thermogravimetric analysis, differential scanning calorimetry, and UV-Vis spectroscopy.
• Single-crystal X-ray diffraction (SCXRD) analysis to elucidate structural changes.

Main Results:

• Rod-shaped crystals exhibited reversible thermofluorochromic behavior between 20-40 °C.
• Heating induced a fluorescence redshift (594 to 633 nm) and a 5-fold quantum yield enhancement.
• SCXRD revealed thermal disruption of Se···π interactions, leading to conformational planarization and enhanced conjugation.

Conclusions:

• The developed crystals demonstrate a robust mechanism for reversible optical switching via thermal stimulation.
• The system shows potential for advanced smart optical materials and biorelated technologies due to its stability and reversibility.