Stepwise Stimuli-Responsive, Multicolor-Chromic Perylene Bisimide/Polyvinyl Alcohol Co-assembly System for Information Encryption.

The issue of information security has become a concern in all aspects of daily life, prompting the development of encryption technologies. Therein, optical encryption using color/graphical patterns holds great potential. However, current approaches generally rely on monochromic change upon one or more stimuli, limiting their further application in advanced confidential encryption. Herein, we propose a delicate strategy based on a co-assembly system of perylene bisimides (PBI)/polyvinyl alcohol (PVA) that demonstrates stepwise stimuli response and multicolor changes. The color of the supramolecular system changes from red to purple under the stimulus of UV light, and to orange when exposed to water. The multidimensional chromic response is achieved by an evolution process including the generation, packing rearrangement and quenching of PBI radical anions/dianions. With the virtues of photo- and hydrochromism, this novel co-assembly system was successfully employed for advanced anticounterfeiting and versatile information encryption applications.