Ultralong Phosphorescence from Organic Ionic Crystals under Ambient Conditions

Area of Science:

• Materials Science
• Solid-State Chemistry
• Photophysics

Background:

• Ultralong organic phosphorescence (UOP) is a desirable property for advanced materials.
• Developing new UOP materials with tunable emission and long lifetimes remains a challenge.

Purpose of the Study:

• To synthesize and characterize novel organic salts exhibiting UOP under ambient conditions.
• To investigate the effect of cation variation on UOP properties.
• To explore the potential of these materials for gas sensing applications.

Main Methods:

• Synthesis of organic salts with varying cations (NH4+, Na+, K+).
• Characterization of photophysical properties, including emission spectra and lifetimes.
• Single-crystal X-ray diffraction analysis.
• Investigation of reversible phosphorescence upon exposure to fuming gases (ammonia, hydrogen chloride).

Main Results:

• Organic salts in the crystal state demonstrated UOP with emission lifetimes exceeding 504 ms.
• Tunable UOP colors from sky blue to yellow-green were achieved by altering cations.
• Single-crystal analysis revealed ionic bonding facilitates ordered structures and molecular aggregation for UOP.
• Reversible ultralong phosphorescence was observed upon exposure to ammonia and hydrogen chloride gases.

Conclusions:

• Ionic bonding in organic salts is crucial for achieving UOP.
• Cation choice allows for tuning of UOP color and lifetime.
• These materials show promise for visual gas sensing of ammonia and hydrogen chloride.
• An environmentally responsible and practical synthetic route for UOP materials was established.