Dynamic Fluorescence Materials Based on Naphthalimide-Functionalized Silica Aerogels Covalently Grafted with Spiropyran: Applications in Advanced Information Encryption

• • Covalent grafting of spiropyran (SP) at 1%, 2%, and 3% w/w onto naphthalimide-functionalized silica aerogels enables programmable fluorescence chromatic transitions from green (blue) to red via FRET, with response speed and color contrast suitable for time-dependent digital encryption. Industrial impact: provides a tunable platform for anti-counterfeiting labels with multiple security levels, reducing counterfeit risk by exponentially increasing decoding complexity. • • The aggregation-induced emission (AIE) of SP is harnessed by controlling amino group dispersion on the aerogel surface, which directly governs SP molecular packing and reversibly modulates red fluorescence. This spatial manipulation allows on-demand switching of emission, critical for dynamic information encryption where the signal must be toggled by external stimuli. • • A screen-printed QR code ink formulated with the composite and PVP remains invisible under ambient light but becomes scannable only after a specific UV exposure time, demonstrating a practical encryption protocol. This time-gated readout adds a temporal dimension to authentication, thwarting static copying and unauthorized scanning. • • The material exhibits fast response speed and strong contrast in color and fluorescence emission, but photostability is identified as a limitation requiring further improvement (Table S3). For industrial deployment, enhanced photostability is essential to ensure reliable long-term operation in security tags exposed to ambient light.