The photoresponse of diarylethene crystalsi s found to depend on the intensity of UV light, that is, photoinduced bending is switched to photosalient phenomenab y increasing the light intensity.T he change in the size of the crystal unit cell upon UV irradiation is larger for asymmetric diarylethenes with thiazole and thiophene rings than that for the corresponding symmetric diarylethenes. As ar esult, the crystalso fa na symmetric diarylethenes how much more drastic photosalient effects than those of the corresponding symmetric diarylethene crystals upon UV irradiation. It is also found that the crystals of diarylethene, which have not previously been reported to exhibit ap hotosalient effect, show photosalient phenomena upon irradiation with strong UV light. Furthermore, the dependence of photosalientp henomenaont he size and shape of the crystals is reported.

Photopharmacology has been attracting attention for the development of drugs with fewer side effects and toxicity by introducing a photoswitch structure in the drug and controlling its spatiotemporal effects by...

This study presents phototunable organic golden luster material. We adopted photochromic diarylethene to produce this material. Through recrystallization, the compound formed plate-like microcrystals, which were then laminated to form a film. The yellowish gold-colored textured film was achieved by a combination of diarylethene absorption and specular reflection from the surface of the stacked microcrystals. The produced films showed a change in color to deep gold upon UV light irradiation due to the change in the absorption band caused by the photocyclization of diarylethene. The film reverted to its original color upon exposure to visible light due to the photocycloreversion of the diarylethene. Such photoresponsive metallic luster in a material could have a significant impact on applications in the decoration and ink industries by avoiding the use of actual precious metals.

Photomechanical materials driven by an external light stimulus have become the focus of much attention. We can operate them in a noncontact way and remotely. Photoinduced bending, one of the typical photomechanical behaviors, is often observed in elongated and thinner crystals, which makes them a promising candidate for a variety of applications. However, the preparation of crystals appropriate for bending behavior is difficult because of the complexity of their molecular structures, preparation conditions, and other factors. Here, an efficient surface peeling of crystals by multistep light irradiation using diarylethene crystals is reported. Thin crystals fabricated by this approach make up less than half the thickness of the original crystals. This shows the potential for the photocontrol of various photomechanical behaviors by the same crystal depending on the irradiation conditions.

Background: Diarylethenes are well-known photochromic compounds, which undergo cyclization and cycloreversion reactions between open- and closed-ring isomers. Recently, diarylethene derivatives with photoswitchable fluorescent properties were prepared. They are applicable for fluorescence imaging including bio-imaging. On the other hand, a new system called “excited state intramolecular proton transfer (ESIPT)” is reported. In the system, absorption and emission bands are largely separated due to the proton transfer, hence it showed strong fluorescence even in the crystalline state. We aimed to construct the photochromic system incorporating the ESIPT mechanism. Results: A diarylethene incorporating a fluorescent moiety that exhibit ESIPT behavior was prepared. The ESIPT is one of the examples which express the mechanisms of aggregation-induced emission (AIE). This compound emits orange fluorescence with a large Stokes shift derived from ESIPT in aprotic solvents such as THF or hexane, while it exhibits only a photochromic reaction in protic solvents such as methanol. In addition, it shows turn-off type fluorescence switching in an aprotic solvent and in crystals. The fluorescence is quenched as the content of closed-ring isomers increases upon UV light irradiation. Conclusions: A diarylethene containing an ESIPT functional group was prepared. It showed fluorescent turn-off behavior during photochromism in aprotic solvents as well as in crystalline state upon UV light irradiation. Furthermore, it showed AIE in THF/water mixtures with blue-shift of the emission.