Light-Harvesting System with Photo-Tunable Property for Time-Resolved Encryption and Anti-Counterfeiting

Photo-tunable smart materials with time-dependent optical characteristics are gaining prominence as versatile platforms for time-resolved information encryption and dynamic anti-counterfeiting. However, the fine manipulation of fluorescent performance to achieve dynamic fluorescence properties in the time dimension remains a great challenge. Herein, we developed a supramolecular artificial light-harvesting system with photo-controlled switching properties. In this system, a tetraphenylethylene (TPE)-based platinum(II) metallacycle served as the energy donor, while the photochromic spiropyran moieties were precisely incorporated into the TPE side chains through amide linkages. This architectural design not only significantly enhances the light-harvesting efficiency and energy conversion capability but also endows the system with unique photo-responsive characteristics. With UV light irradiation, the spiropyran units were ring-opened to generate merocyanine (MC), causing efficient energy transfer from the photoexcited metallacycle to the MC acceptors and triggering reversible photochromic transformation. Subsequent incorporation of Cy5 as the secondary energy acceptor enabled the construction of a cascade energy transfer system, facilitating dynamic fluorescence color modulation. The unique photophysical properties of this system were successfully exploited for time-resolved information encryption and dynamic anti-counterfeiting. This work not only provides fundamental insights for supramolecular chemistry and photo-functional materials but also offers promising avenues for advanced information security applications.