In our body, a large number of molecules work cooperatively. As the result of the cooperation, molecules show special functions that the molecule cannot realize by alone. The aim of our research is fully-artificial creation of such a “super function” due to networks in multi-molecular systems, in vitro. This novel research field is known as Systems Chemistry.
The best research result is shown in Figure 1. Generally, to make the repetitive motion of light-responsive materials, switching of light is required. However, the azobenzene crystals in the figure periodically flip under steady light irradiation. The mechanism for the self-continuous motion is shown in Figure 2. In the original phase of the crystal, the forward reaction (trans-to-cis photoisomerization) occurs, and the increasing in the cis-isomer ratio induces a subcritical phase transition to a metastable crystal phase. In the newly formed crystal, cis-to-trans photoisomerization occurs, and the decrease in the cis-isomer ratio induces the reverse phase transition to the original crystal phase. Repeating the dynamics spontaneously, the crystal flips repetitively. Hokkaido University press-released the result with the title of “On the path toward molecular robots”. The news was translated into more than ten languages by publishers. You may watch the movie of clione-like motion of crystal from YouTube (Figure 3).
When we construct such self-organized dynamics, self-assembly of molecules is also a key dynamics. As shown in Figure 4, the dynamics to form molecular assembly is quite interesting. The helical assembly, the size in the figure is several ten micrometers, grew to one centimeter-length assembly by 3-days incubation. The formation is involved with multi-molecular dynamics.
To investigate the feature of multi-molecular systems, the researcher applies his skill for organic synthesis. And home-made equipment is employed for physical measurements. An example of organic synthesis is shown in Figure 5.
The field of the research group is in multidiscipline area. All who interested in the research is welcomed to join.