Photo-Programmable Synergistic Responses of Phenothiazine-Diarylethene Hybrids: From Molecular Engineering to Electrochromism and Information Encryption

A series of phenothiazine-modified diarylethene derivatives (1z-6z) were designed via molecular engineering to achieve multi-stimuli responsive photochromic materials. By precisely modulating donor linkage and conjugated bridge length, the absorption wavelengths of closed-ring isomers were effectively tuned, enabling broad color variation from yellow to deep purple. Notably, 3z and 4z, featuring a single benzene bridge, exhibit superior multi-stimuli responsive performance. Beyond retaining intrinsic reversible photochromism and fluorescence switching, they display a distinctive "photo-oxidation" synergistic mechanism. UV-induced closed-ring isomers reconstruct the electron delocalization pathway of oxidized products through a strong D-π-A architecture, inducing a precise red shift to the mid-visible region and enabling high-contrast color transitions (red/purple to blue) independent of stimulus sequence. Electrochemical investigations further reveal that modulation of the oxidation potential via a photoinduced conformational gating effect serves as the fundamental basis for this synergistic behavior. Leveraging their solid-state responsiveness, gel-based electrochromic devices were fabricated, and a multi-component dynamic information encryption system was constructed, demonstrating multilevel anti-counterfeiting and information concealment. This work presents tunable, multi-responsive photochromic materials and a referable molecular engineering strategy for designing photo-electro-chemical synergistic triad systems.