Unforgeable Red: Design and Application of SO-Annulated Perylene Diimides for Anti-Counterfeiting.

The modernization of counterfeiting activities represents a threat to society, making difficult to detect and eliminate fraudulent products. In this context, innovation in anti-counterfeiting technologies is crucial to protect intellectual property and increase the level of security. Herein, we report the first sulfoxide-annulated perylene diimides (PDI-SO) as versatile photoactive materials for advanced anti-counterfeiting. Chemoselective mono-oxidation of S-bridged perylene diimides affords a red-emissive PDI-SO dye that undergoes rapid, quantitative visible light-induced deoxygenation to give the green-emissive PDI-S. The materials retain high fluorescence efficiency, thermal robustness, and excellent processability, allowing patterning from the centimeter to micrometer scale using low-cost masks, high-resolution photolithography, and maskless photopatterning, and enabling dual optical readouts. Applications on textiles and electronic substrates coupled with molecular verification via swab-mass spectrometry demonstrate that SO-bridged PDIs provide a powerful, multi-level, and difficult-to-replicate platform for secure authentication technologies.