Acid/Base-driven visualized molecular hinge for advanced information encryption

Abstract

Dynamically stimuli-responsive fluorescent switches possessing multiple optical outputs provide a promising opportunity for high-level security encryption. Herein, we take the advantage of reversible transformation based on molecular machines to construct an artificial molecular hinge utilizing pyridine, and phenyl and alkynyl groups as the building blocks to establish the hinge wings and rigid axis, respectively. The reversible rotary motion of the molecular hinge can be conveniently regulated, accompanied by multicolor fluorescence changes from the blue to yellow–red region, including white light emission through finely manipulating the protonation-deprotonation processes of the pyridine wing. Based on the multicolor fluorescence characteristic, the information-encrypted materials are conceived as pattern codes that can be quickly and accurately identified by smartphone. Importantly, the temporal feature endows the molecular hinge with time-dependent characteristic, thus pattern codes have been achieved for multi-information storage and information correction. The present work provides a design rationale for better understanding of the relationship between molecular structure, molecular motion and tunable optical properties and paves a way towards constructing advanced encryption materials with higher security requirements.