430
S. Kobatake and D. Kitagawa
(a)
(b)
Fig. 25.2 a Diarylethene derivatives and b others that exhibit crystalline photomechanical response
Fig. 25.3 Geometrical structures of diarylethene open- and closed-ring isomers
diarylethene crystal. As described above, when UV light is irradiated onto a thin
crystal, the entire crystal reacts almost uniformly, resulting in the crystal shape
change. This crystal shape change is observed when the molecular packing is the
same even if the molecular structure is different. When light is applied non-uniformly
to a slightly thicker crystal, the photochromic reaction proceeds only on the crystal
surface, and the crystal bends like a bimetal. The contraction/elongation and bending
deformation of the crystal are basically the same phenomena. When the rod-like
crystal of diarylethene 2 is irradiated with UV light, the crystal bends in the direction of the incident light and returns to the original rod-like crystal when irradiated
S. Kobatake and D. Kitagawa
(a)
(b)
Fig. 25.2 a Diarylethene derivatives and b others that exhibit crystalline photomechanical response
Fig. 25.3 Geometrical structures of diarylethene open- and closed-ring isomers
diarylethene crystal. As described above, when UV light is irradiated onto a thin
crystal, the entire crystal reacts almost uniformly, resulting in the crystal shape
change. This crystal shape change is observed when the molecular packing is the
same even if the molecular structure is different. When light is applied non-uniformly
to a slightly thicker crystal, the photochromic reaction proceeds only on the crystal
surface, and the crystal bends like a bimetal. The contraction/elongation and bending
deformation of the crystal are basically the same phenomena. When the rod-like
crystal of diarylethene 2 is irradiated with UV light, the crystal bends in the direction of the incident light and returns to the original rod-like crystal when irradiated