Cyanostyrene derivative with multi-stimuli responsive properties: Multicolor- and high-color-contrast switching in response to force, heat and light

Multi-stimuli responsive luminescent materials are ideal materials for luminescent anti-counterfeiting technology. Currently, it is still challenging to develop excellent multi-stimuli-responsive material that is easy to synthesize and low-cost. Herein, a dicyanostilbenebenzene derivative (α-CFP) with a symmetrical structure was designed and successfully synthesized, which showed obvious AIE and solvent effects in solution. Two polymorphs of it were prepared by controlling the cooling rate, and it was found that green-emitting Form I and blue-emitting Form II can transform into each other by heat and mechanical force. Crystal structure analysis reveals the possible intrinsic mechanism of polymorphism-dependent emission and interconversion. Further studies found that both Form I and Form II could transform into another new polymorph Form III upon heating to 220 °C. Form III can undergo photoinduced [2 + 2] cycloaddition reaction accompanied by discoloration, and it can return to its original state by heating. Finally, three application scenarios were designed and demonstrated, which confirm their potential applications in information encryption and anti-counterfeiting.