Emergence of Radiochromic Metal–Organic Frameworks for Information Encryption via Dual-Stimuli Responses

Secure information encryption is paramount in modern society for data protection, anticounterfeiting, and confidential communication. Here, we report the first demonstration of radiochromic metal-organic frameworks (MOFs) for high-security information encryption, leveraging their unique X-ray-induced chromic responses. Three thorium-based MOFs (<b>Htpc</b>⊂<b>TOF</b>, <b>Hmpc</b>⊂<b>TOF</b>, and <b>Hpybz</b>⊂<b>TOF</b>) were rationally constructed by embedding distinct pyridine-derived guest molecules within a robust layered Th₆(μ₃-O)₄(μ₃-OH)₄(HCOO)₁₂(DMF)₂·2DMF host framework. Remarkably, upon X-ray irradiation, each framework exhibits well-defined and distinguishable color transformations, including purple for <b>Htpc</b>⊂<b>TOF</b>, yellow for <b>Hmpc</b>⊂<b>TOF</b>, and green for <b>Hpybz</b>⊂<b>TOF</b>, while <b>Htpc</b>⊂<b>TOF</b> additionally responds to ultraviolet (UV) light, enabling dual-stimuli activation. This hierarchical, sequential chromic switching facilitates multilevel decryption, significantly enhancing encryption complexity and thwarting unauthorized access. Proof-of-concept demonstrations, including barcodes, QR codes, and 3D color matrices, illustrate the potential of these MOFs for spatially encoded, temporally controlled, and multidimensional information encryption. The frameworks exhibit excellent chemical, thermal, and radiative stability, maintaining structural integrity under different conditions, including high dose ionizing radiation, heating to 200 °C, and prolonged water exposure. Collectively, these findings establish a new paradigm for robust, stimuli-responsive MOFs, marking the first use of radiochromism in advanced information encryption technology.