A sodium carboxymethyl cellulose-induced emission and gelation system for time-dependent information encryption and...

Many lanthanide complexes do not form gel or even exhibit characteristic luminescence of lanthanide ions, which limits their applications in many fields. Therefore, there is an urgent need for a third component that can not only promote emission but also gel the lanthanide complex system to construct new smart materials such as time-dependent information encryption and anti-counterfeiting materials. Herein, a luminescent lanthanide metallogel was successfully prepared by using the third component sodium carboxymethyl cellulose (NaCMC) to induce the gelation and luminescence of the complex (H₃L/Tb³⁺) of 4,4',4″-((benzene-1,3,5-tricarbonyl)tris(azanediyl)) tris(2-hydroxybenzoic acid) (H₃L) and Tb³⁺. The H₃L/Tb³⁺ complex itself does not form gel and has no characteristic luminescence of Tb³⁺. Moreover, the multicolor emission of H₃L/Tb³⁺/NaCMC gels was prepared based on Förster resonance energy transfer (FRET) platforms to obtain a high-security level information encryption and anti-counterfeiting materials. These multicolor emission gels exhibit emission color tunability with time dependence due to the different energy transfer efficiencies at each pH node controlled by glucono-δ-lactone hydrolysis time. Based on the time response characteristics, the time-dependent information encryption and anti-counterfeiting materials are developed.