Dynamic Time‐Dependent Emission in Solution and Stable Dual Emission in Solid Matrix Exhibited by a Single‐Component Fluorescence System

Organic luminescent materials with time-dependent emission colors show promising applications in the fields of chemical sensing, high-resolution bioimaging, and high-security information encryption. Herein a time-dependent fluorescence system based on a spirocyclic scaffold-bridged cyanostilbene dimer (SDCS) as the single component in a mixed CH3CN/H2O solvent is presented. Specifically, the original orange-emitting nanoparticles prepared from SDCS by reprecipitation can transform into green-emitting nanosheets over time driven by supramolecular self-assembly. It is worth noting that such a transformation rate can be controlled by tuning the water fraction. Based on these unique properties, fluorescent binary codes are developed, enabling time-dependent information encryption with a higher level of security. Moreover, the dual color can be individually fixed by solid matrices such as hydrogel or powder. The obtained luminescent powders are successfully used in two-color fluorescence imaging of latent fingerprints. This work demonstrates the use of a supramolecular strategy to control multiple emissions in a single-component system for multifunctional applications. A spirocyclic-scaffold-bridged cyanostilbene dimer (SDCS) is designed and synthesized, which exhibits multiple fluorescence properties: excited-state intramolecular proton-transfer (ESIPT), aggregation-induced emission enhancement (AIEE), and time-dependent self-assembly induced emission (TD/SAIE). Based on the ESIPT-AIEE-TD/SAIE triple fluorescence mechanism, SDCS can be used for time-dependent information encryption and two-color fluorescence imaging of latent fingerprints.image