Morphology change of diarylethene derivatives having benzofuran derivatives—Photoinduced crystallization

We have synthesized three diarylethene derivatives — 1,2-bis(2-(4-n-alkylphenyl)benzofuran-3-yl)ethenes (1a–3a). We have observed the morphology changes of the melted diarylethenes after heating. The crystal of 2a melts at 102 °C. After heating at 130 °C, the liquid did not crystallize below 40 °C for more than 3 days because of the temperature above the eutectic point. When the liquid was irradiated with 365 nm light, the photoirradiated area crystallized, because of the generation of 2b. After the sample was irradiated with visible light, the crystals changed to a colorless liquid. Photoinduced crystallization was also observed for the 4-n-dodecyl derivative (3a).