Study on a novel dye with multi-stimulus response based on spiropyran

Stimuli-responsive molecules have attracted attention for a wide range of applications in many functional materials. Spiropyrans, as typical stimuli-responsive molecules, require a certain degree of conformational freedom to guarantee reversible isomerization, which is difficult to be ensured in the solid state. Therefore, in this paper, bisphenol fluorene with orthorhombic structure is introduced on the nitrogen atom of spiropyran through a simple esterification reaction, and obtain a novel molecule, SPB, which has light, thermal and acid/base responsive ability. SPB not only maintains excellent responsive properties to light, thermal, and acid/base stimuli in solution state, it but also displays perfect response performance to these stimuli in the powder state and in poly(methyl methacrylate) film. And there are high sensitivity, high color contrast and high emission contrast between open- and close-ring structure. In addition, SPB has more excellent reversibility and thermal stability, and it remain responsive ability after 40 reversible cycles. SPB can be used for UV printing and anti-counterfeiting materials. With this simple and rational structural design strategy, more liquid\solid stimulus responsive materials could be produced.