Multi-stimuli-responsive lanthanide metallogels with chromic behaviors for time-resolved information encryption and...

Multi-stimuli responsive fluorescent materials exhibiting time-resolved color changes offer dynamic multi-modal optical features that significantly enhance the security of information encryption and anti-counterfeiting systems. This paper presents a luminescent lanthanide metallogel capable of programmable, time-dependent, and multi-level encryption. This was achieved through the independent modulation of multiple optical information layers in response to various external stimuli. The green-emissive gel was constructed by co-assembling terbium ions (Tb³⁺) with the organic ligand 4,4',4''-(1,3,5-triazine-2,4,6-triimino)-tribenzoic acid (H₃L). Additionally, the incorporation of sulforhodamine B and a spiropyran derivative enabled efficient cascade energy transfer and multi-stimuli-responsive fluorescence modulation. Notably, the resulting gel exhibited visible light-induced photochromism, thermochromism, and acidochromism within a single platform. By programming a sequence of stimuli, the system achieved multi-level and temporally resolved color transitions, demonstrating advanced potential for use in secure information encryption and anti-counterfeiting. Overall, this study provides a versatile strategy for designing dynamic multi-stimuli-responsive soft materials for advanced optical security technologies.