Multidimension‐Regulated Dynamic Timing Control Over Multicolor Emission of Host–Guest Assemblies for Information Encryption and Advanced Anti‐Counterfeiting

Abstract

AbstractDynamical control over molecular luminescence, especially in a time‐dependent manner, holds great promise for the development of smart luminescent materials for anti‐counterfeiting and preventing information leakage. Herein, a series of self‐assembled systems are reported using pillar[5]arene (DMP[5]) and spiropyran derivatives (SP‐C4‐Py). The assemblies rely on the time‐encoded locking and unlocking ring‐switching and fluorescence resonance energy transfer (FRET) units for information camouflage and multilevel encryption. DMP[5] with cyan solid fluorescence color acts as the host and energy transfer (EnT) donor, while photochromic SP‐C4‐Py with the ring‐opened and closed isomers acts as guest and EnT acceptor. When irradiated, the assemblies undergo a time‐dependent luminescence color change ranging from cyan to yellow to red through a FRET process. The molar ratio of host and guest in the assembly systems affects the FRET efficiency, and the power of the irradiation source influences the isomerization degree and rate of SP‐C4‐Py, allowing for precise control over the fluorescent color transition time. The combination of molecular composition and external stimuli governs the kinetics of color change, resulting in a difference in the appearance time of a specific fluorescent color pre‐designed as correct authorized information. By combining these diverse assembles in one label, information encryption and dynamic information identification are achieved in the dimensions of time, ratio, and light power. This time‐dependent feature offers the assembly materials with a multilevel security and provides new possibilities for anti‐counterfeiting and blocking information leakage.