Remarkable Off-On Tunable Solid-State Luminescence by the Regulation of Pyrene Dimer

Area of Science:

• Materials Science
• Photochemistry
• Supramolecular Chemistry

Background:

• Achieving controllable "off-on" luminescence through non-covalent interactions remains a significant challenge.
• Luminescent materials are crucial for advanced applications like anti-counterfeiting and sensors.
• Understanding the relationship between molecular packing and photophysical properties is key to designing functional materials.

Purpose of the Study:

• To develop a high-performance "off-on" tunable luminescent material using a novel molecule.
• To investigate the mechanism behind the luminescence switching behavior.
• To explore the potential of this material in stimuli-responsive applications.

Main Methods:

• Synthesis of a novel molecule (TFPA) comprising pyrene and cyanostilbene units.
• Investigation of luminescence properties under different stimuli (grinding, UV irradiation, thermal annealing).
• Utilizing theoretical calculations and experimental analysis to elucidate the switching mechanism.

Main Results:

• The pristine TFPA crystal exhibited near-zero emission, acting as an "off" state.
• Grinding or UV irradiation induced significant luminescence enhancement, transitioning to the "on" state.
• The "on" state demonstrated reversibility, returning to the "off" state upon thermal annealing.

Conclusions:

• A novel strategy for "off-on" luminescence switching was established based on molecular packing modifications.
• The observed switching behavior is attributed to changes in intermolecular interactions and pi-pi stacking of pyrene moieties.
• The developed material shows promise for stimuli-responsive applications, including anti-counterfeiting technologies.