Mechanically Induced Transient Fluorescence of Photochromic Diarylethene Crystals for Sensing and Security Material

Abstract Luminescent materials responding to mechanical stimulation can visualize the strain and mechanical damage applied to objects. Mechanofluorochromism is a well‐known phenomenon induced by the mechanical force on fluorescent crystalline materials. However, simple application of the mechanofluorochromism is unsuitable for temporally and spatially detecting stress in detail because the fluorescent state is kept for rather long period. Here, the dynamic stress‐sensing luminescent solid material of a photochromic diarylethene with a fluorescent moiety is reported. Under the stress applied to the crystalline state, this material emitted cyan‐colored transient fluorescence that is rapidly diminished within a few second. This dynamic fluorescence phenomenon is well controlled by the combination of light irradiation and other external stimuli (organic solvent vapor and/or heat). In addition, the luminescence period is regulated by the excitation wavelength and magnitude of applied force. By utilizing these responses, the rewritable dynamic information encryption is successfully demonstrated. This material with transient fluorescence overcomes the persistence of fluorescence color of mechanochromism and present results provide a new principle for multifunctional light‐emitting materials responding to mechanical stimulation.