Fluorescence photoswitch of stiff-stilbene derivatives for anti-counterfeiting

Precise improvement of photo-isomerized reaction of molecular photoswitches is a greatly meaningful research topic for the fabrication of high-performance smart materials. Herein, a series of stiff-stilbene derivatives with substituents of different electronic effects were designed and prepared handily through Suzuki coupling reaction. Through studying their photoisomerization properties, we disclosed the influence law of electronic effect on photoisomerization properties of stiff-stilbenes that strong electron-donating and electron-deficient groups located in the counterposition of stiff-stilbenes on the benzene ring were not conducive to photochromism performance of stiff-stilbene skeleton. The (E)-form of these stiff-stilbenes, a new class of fluorescence dyes, showed good photoluminescence performance, and dramatically stronger than their (Z)-isomers. Importantly, we witnessed a fascinating photo-modulating fluorescence behavior for these molecular photoswitches, which were further applied in high-secrecy-level anti-counterfeiting. The study provided a reference for the design of excellent molecular photoswitches with purpose and precision and the development of new intelligent optical materials.