Amphiphilic diarylethenes bearing octyloxycarbonyl and N-octylcarbamoyl groups have been designed and synthesized. These ester- and amide-linked compounds form micrometer-sized supramolecular assemblies in water, and these assemblies exhibit photoinduced macroscopic morphological transformations upon alternate irradiation with UV and visible light. The ester-linked diarylethene showed a transformation between colorless spheres and a red-purple hazy fringe, whereas the microspheres of the amide-linked diarylethene showed changes in color, size, and shape, but the spheres did not show division. TEM images revealed that the spheres of the open-ring isomers have coacervate structures, with bicontinuous aqueous and organic phases. The closed-ring isomers of the ester- and amide-linked compounds were found to form nanofibers and thin layers, respectively. These compounds showed absorption spectral shifts at temperatures corresponding to the lower critical solution temperature (LCST) transition. This morphological transformation can be rationalized as the photoinduced phase transition between the high- and low-temperature phases of the LCST transition. These results open up a new avenue for the design of phototransformative supramolecular assemblies based on a combination of photochromism and LCST behavior.

Photoinduced clustering of polystyrene microbeads and photocontrol of their diffusion was achieved in water with the assistance of photoinduced transformation of supramolecular architecture of amphiphilic diarylethene between sphere and fiber states. When a suspension of polystyrene beads containing the sphere state of diarylethene was UV-irradiated from beneath, clustering of the polystyrene beads by thermal convection was observed. The velocity of clustering was dependent on the amount of photogenerated nanofibers that determines the viscosity of the water. Diffusion of the clustered polymer beads was suppressed by the surrounding fibers, but was restored to regular Brownian motion upon irradiation with visible light. It was suggested that the diffusion of the microbeads was controlled by the transformation of aggregates between the more viscous fiber state and the less viscous sphere state. These results provide new insight into the photocontrol of particle motion in fluidic media.

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Amphiphilic compounds with oligo(ethylene glycol) unit form self‐assembled architectures and exhibit lower critical solution temperature (LCST) behavior. Amphiphilic diarylethenes with ester and amide linker are reported. These compounds formed micrometer‐sized supramolecular assemblies in water, and these assemblies exhibited reversible photoinduced macroscopic morphological transformation. The morphological transformation is understood as the photoinduced phase transition between the high‐ and low‐temperature phases of LCST transition. These results open the way of design of phototransformative supramolecular assembly. More information can be found in the Full Paper by K. Higashiguchi, K. Matsuda et al. on page 15059.