Photo-Stimuli-Responsive Dual-Emitting Luminescence of Spiropyran-Encapsulated Metal-Organic Framework for Dynamic Information Encryption.

The development of photo-stimuli-responsive luminescent materials is essential to address emerging demands in encryption security. Here, we report a novel photo-stimuli-responsive dual-emitting luminescent material ZJU-128⊃SP (SP = spiropyran), which was obtained by encapsulating spiropyran molecule into a cadmium-based metal-organic framework (MOF), [Cd 3 (TCPP) 2 ]·4DMF·4H 2 O (ZJU-128, H 4 TCPP = 2,3,5,6-tetrakis (4-carboxyphenyl)pyrazine). This MOF/dye composite ZJU-128⊃SP exhibits a blue emission from ligand of ZJU-128 at 447 nm and a red emitting around 650 nm of spiropyran. Utilizing the photoisomerization of spiropyran from ring-closed to ring-open form under UV light irradiation, significant fluorescence resonance energy transfer process between ZJU-128 and spiropyran is achieved. As a result, the blue emission of ZJU-128 is gradually decreased while the red emission of spiropyran increased. This dynamic fluorescent behavior can fully recover to original state when exposed to visible light (> 405 nm). By taking advantage of the time-dependent fluorescence, dynamical anti-counterfeiting pattern and multiplexed coding are successfully developed based on ZJU-128⊃SP film. This work provides an inspiring point for the design of information encryption materials with higher security requirements. This article is protected by copyright. All rights reserved.