Supramolecular Assembly-Driven Multilevel Fluorescent Encryption

The growing demand for information security in the digital era has accelerated the development of novel encryption materials, among which optically responsive systems have emerged as particularly promising candidates due to their exceptional tunability and noninvasive characteristics. However, current optical encryption materials remain largely confined to static or binary states, presenting a fundamental challenge in achieving precisely controlled hierarchically responses for developing high-capacity, multilevel encrypted materials. Herein, we successfully construct a novel class of dynamically multilevel responsive luminescent materials driven by supramolecular self-assembly and apply them to a multilevel information encryption system. The highly efficient host-guest complexation between 4-phenylpyridine-functionalized isoquinoline derivatives (IQP) and macrocyclic molecule CB[8] enables the construction of linear supramolecular polymers (IQP⊂CB[8]). Affected by the dynamic protonation of isoquinoline and the host-guest interaction, the monomer and polymer exhibit the characteristics of multicolor luminescence. Furthermore, IQP can undergo a reversible [2+2] photocycloaddition reaction in the confined space of CB[8], it can reversibly transform from a conjugated supramolecular polymer to a nonconjugated polyrotaxane and shows pronounced optical response on the time gradient. Consequently, this light, heat, acid/base-sensitive supramolecular system exhibits reversible responsiveness and time-dependent characteristics, thereby establishing a multichannel fluorescent cascade encryption platform capable of multilevel information encryption.