Overcoming ACQ: DPA-modified TICT-type AIEgens for high-resolution and multilevel latent fingerprint visualization

Area of Science:

• Forensic Science
• Materials Chemistry

Background:

• Latent fingerprints (LFPs) are crucial for identification but challenging to image at high resolution.
• Aggregation-induced emission luminogens (AIEgens) show promise for high-contrast visualization due to their luminescence in aggregated states.

Purpose of the Study:

• To design and synthesize novel AIEgens for sensitive and nondestructive latent fingerprint visualization.
• To investigate the structure-property relationships of AIEgens for improved fingerprint imaging.

Main Methods:

• Synthesized novel AIEgens incorporating diphenylamine (DPA) donor groups onto a quinazolinone core.
• Investigated the photophysical properties, including fluorescence and phosphorescence, of the synthesized AIEgens.
• Evaluated the performance of AIEgens for latent fingerprint visualization on various substrates.

Main Results:

• The designed AIEgens exhibited pronounced aggregation-induced emission (AIE) characteristics, transforming from aggregation-caused quenching (ACQ) behavior.
• The molecules displayed intense blue fluorescence, ultralong phosphorescence lifetimes, and a "turn-on" response to eccrine gland lipids.
• High-resolution visualization of level 1-3 fingerprint details was achieved on smooth surfaces.

Conclusions:

• The novel DPA-functionalized quinazolinone AIEgens are effective for high-contrast, sensitive, and nondestructive latent fingerprint identification.
• The developed AIEgens demonstrate a promising advancement in forensic science imaging techniques.
• The design strategy successfully converted ACQ to AIE, enabling superior fingerprint visualization.