Circularly polarized lanthanide luminescence for advanced security inks.

Area of Science:

• Materials Science
• Photochemistry
• Analytical Chemistry

Background:

• Security inks are crucial for global commerce, security, and health.
• Lanthanide complexes are utilized in luminescent security inks due to their photophysical properties.
• Circularly polarized luminescence (CPL) offers a chiral fingerprint but is underexploited in security inks.

Purpose of the Study:

• To review the potential of lanthanide-based, CPL-active security inks.
• To highlight recent advances in CPL analysis and read-out technologies for security applications.
• To systematically analyze CPL-active lanthanide complexes for suitability in advanced security inks.

Main Methods:

• Introduction to circularly polarized luminescence (CPL) and its principles.
• Review of recent technological advancements in CPL analysis and detection.
• Meta-analysis of CPL-active lanthanide complexes (Euⁱⁱⁱ, Tbⁱⁱⁱ, Smⁱⁱⁱ, Ybⁱⁱⁱ, Cmⁱⁱⁱ, Dyⁱⁱⁱ, Crⁱⁱⁱ).

Main Results:

• Lanthanide complexes can be engineered for CPL, providing unique chiral signatures.
• Advances in CPL technology facilitate practical applications in security inks.
• Several lanthanide complexes exhibit strong CPL, with specific candidates identified as promising.

Conclusions:

• Chiral CPL signals represent a significant, yet untapped, security feature for advanced inks.
• Further development of CPL-active lanthanide complexes and read-out systems is recommended.
• This review provides a roadmap for advancing CPL-based security ink technology.