LAUSR

Abstract We report the synthesis and photoluminescence (PL) behavior of a new molecular system, which is composed of three positional isomers. They exhibit isomeric effects on both aggregation-induced emission (AIE) and intramolecular charge transfer (ICT) mechanisms. Furthermore, one of them, i.e., (E)-5-methoxy-2-(((6-methylbenzo [d]thiazol-2- yl)imino)methyl)phenol (MTP3), shows unique mechanochromic fluorescence (MCF) phenomenon. Unlike most MCF materials that would function immediately after applying mechanical force, the MCF character of this material is however recessive with mechanical force, but becomes visible upon fumigation treatment. Given that the MCF is activated under specific conditions, it is termed as conditional mechanochromic fluorescence (CMCF) in this study. In light of the CMCF property of MTP3, a new data encryption-decryption technique was developed. Binary data and complex patterns can be recorded by mechanical force and concealed on the tailor-made data storage. The encoded data cannot be read unless it is fumed by organic vapour, demonstrating a successful encryption-decryption technique. The CMCF offers great potential to be the alternative to encryption algorithms and may contribute greatly to data security and cybercrime prevention.