Multiple Dynamic Anticounterfeiting Using Photochromic Luminescence Organic Cocrystals.

Area of Science:

• Materials Science
• Organic Chemistry
• Supramolecular Chemistry

Background:

• Photochromic and luminescent complexes offer single-signal output, limiting their encryption and anticounterfeiting capabilities.
• Photochromic luminescence (PCL) complexes provide dual output (fluorescence and color change), enhancing security but facing challenges with luminescence quenching via photoinduced electron transfer (PET).

Purpose of the Study:

• To develop an effective strategy for constructing high-security PCL compounds that overcome the luminescence quenching effect.
• To synthesize novel viologen-based cocrystals with fluorescence and color-changing dual output for advanced anticounterfeiting applications.

Main Methods:

• Introducing a highly conjugated luminescent unit into a photochromic molecule.
• Utilizing hydrogen bond interactions to construct highly rigid organic cocrystals.
• Synthesizing and characterizing two novel viologen-based cocrystals.

Main Results:

• Successfully synthesized two viologen-based cocrystals exhibiting fluorescence and color-changing dual output.
• Demonstrated high-security anticounterfeiting properties of the synthesized cocrystals.
• Mechanistic analysis revealed that the highly conjugated unit enhances luminescence and prolongs charge-separated state lifetime, dominating over PET quenching.

Conclusions:

• A strategy involving highly conjugated luminescent units and rigid organic cocrystals effectively overcomes PET quenching in PCL compounds.
• The developed PCL complexes offer a viable solution for high-security anticounterfeiting applications.
• This approach provides a pathway for designing advanced materials with dual output functionalities.