Excitation-Dependent Ionogels Based on Lanthanide-Terpyridine Coordination for Dynamic and Controllable Orthogonal Information Encryption

Smart fluorescence gels provide significant advantages in encryption, such as high storage, user-friendly operation, low cost, and enhanced security. Nevertheless, current fluorescent gels are predominantly limited to static or binary encoding, hindering their potential for high-level multistate encryption. Herein, the ligand (Tpy-Emim) based on terpyridine-vinyl imidazole salt was synthesized. Fluorescent ionogels (P(ACMO/BA/Tpy)-Ln) with robust mechanical properties, strong adhesion, and hydrophobicity were developed through a one-step in situ photopolymerization process. These ionogels exhibited multicolor fluorescence (red, orange, green, white) by adjusting the Eu³⁺/Tb³⁺ ratio. Importantly, the ionogel (P(ACMO/BA/Tpy)-Eu₄₀/Tb₄₀) showed excitation-dependent luminescence with colors changing under different excitation energies. Leveraging this property, a dynamic encryption system was developed, integrating 2D codes into 3D color codes. The 2D code was readable in natural light, while the 3D code required specific UV light to reveal the correct data. Additionally, the ionogel's fluorescence quenched upon exposure to ammonia vapor, enabling decoding of the embedded 2D code. This study provides valuable insights for developing fluorescence ionogels for dynamic and controllable orthogonal information encryption.