422
K. Uchida et al.
Fig. 24.14 a Molecular structures of the open- (left) and closed-ring (right) isomers of diarylethene
derivative 7, b Changes of molecular sizes from 7o to 7c in the crystal, c Molecular packing of 7o
in the unit cell, d photoinduced bending of thin crystal of 7o and the relation to the unit cell
(Fig. 24.15e). The beads immediately scattered with the deformation and breaking
of the walls, in the manner of seeds bursting from impatiens (Fig. 24.15f). This
phenomenon implies that the photoresponsive hollow crystal works as a kind of soft
robot which scatters inclusions by action of light [31].
24.8 Conclusion
We described the fabrication of biomimetic crystalline surfaces. They show specific
wetting properties owing to self-aggregation of photogenerated molecules. These
systems realize that the molecular-level aggregation, which is microscopic, induces
the macroscopic surface functions. At first, we prepared the switching system
in which the aggregation of photochromic molecules is reversible. Secondly, we