Efficient Red Organic Room-Temperature Phosphorescence Enabled by Fused-Cyclization-Induced Planarization for...

Area of Science:

• Materials Science
• Organic Chemistry
• Biomedical Imaging

Background:

• Long-wavelength organic room-temperature phosphorescence (RTP) is valuable for time-resolved imaging due to long lifetimes and low background.
• Efficient red RTP is difficult to achieve because of rapid nonradiative decay and low triplet-state population.

Purpose of the Study:

• To develop a strategy for achieving highly efficient red RTP.
• To investigate the impact of molecular rigidity on phosphorescence properties.
• To enable advanced bioimaging applications using novel RTP materials.

Main Methods:

• Developed a fused-cyclization-induced planarization strategy.
• Synthesized a series of biquinoline-based guests with varying conformations.
• Employed a host-guest doping approach for material optimization.
• Characterized photophysical properties including phosphorescence efficiency and lifetime.

Main Results:

• Fused-ring formation significantly enhanced molecular rigidity and suppressed nonradiative decay.
• Achieved high phosphorescence efficiency (up to 47.53%) and long lifetime (up to 702 ms).
• Optimized material showed bright red emission (616 nm) and excellent dispersibility.
• Demonstrated high-contrast in vivo afterglow imaging with a signal-to-background ratio of 49.2.

Conclusions:

• Fused-cyclization-induced planarization is an effective strategy for designing efficient long-wavelength RTP materials.
• The developed materials show great potential for advanced bioimaging applications.
• The study provides a new pathway for creating high-performance phosphorescent organic materials.