Multiregulated color and fluorescence of a cyanostilbene-based AIEgen by light and pH

Stimuli-responsive aggregation-induced emission (AIE) materials with regulated color and fluorescence have shown promising applications in smart optical systems, while most of them are only regulated by a single stimulus. Herein, a cyanostilbene-based fluorophore ( Z -BDPA) with AIE enhancement properties is elaborately designed, which exhibits multiple regulable color and fluorescence owing to its various photochemical reactions and reversible pH response. After exposure to 420 nm light, the green emission of Z -BDPA in tetrahydrofuran (THF) becomes brighter owing to the Z→E isomerization, which can be recovered under 365 nm irradiation; the yellow fluorescence of Z -BDPA in THF/H 2 O mixtures with 90% water fraction ( f w ) becomes stronger yellow-green fluorescence due to the photodimerization. At acidic conditions, Z -BDPA powder with yellow fluorescence can become another AIEgen Z - p -BDPA with blue fluorescence via protonation, which would be recovered through deprotonation under basic conditions. Under ultraviolet light irradiation, the blue fluorescence of Z - p -BDPA is blue-shifted and increased due to the photo-isomerization and subsequent photocyclodehydrogenation reactions. Based on the regulable color and fluorescence upon the photochemical and pH responses, Z -BDPA has been successfully applied in photo-patterning and anti-counterfeiting.