By Mikiko Tanifuji -
At Japan's National Institute for Materials Science (Sukekatsu Ushioda, president), Senior Researcher Kazunori Sugiyasu and co-workers (Polymer Materials Unit [Izumi Ichinose, unit director], Advanced Key Technologies Division) developed a method for preprogramming the timing of molecules to initiate self-organization by mixing molecules with modified side chains.
Molecular self-organization is widely observed in nature, and is a critical phenomenon in terms of developing systems that perform complex functions as seen in such natural mechanisms as photosynthesis and neurocircuits. Attempts have been made to develop new materials capable of executing advanced functions using the principle behind the phenomenon of molecular self-organization. However, due to the spontaneous nature of molecular self-organization, it is extremely difficult to control the phenomenon by design. In particular, almost no research had been conducted to control the timing of the self-organization phenomenon including control of when to initiate it.
Recently, we conducted research using a molecule that can form two types of self-organized structures. One type of the self-organized structures was quickly formed but was energetically unstable; therefore, after a certain period of time elapsed, the other type of the self-organized structures, which was energetically more stable, was eventually formed. By modifying the side chains of the molecule, thereby inverting the energy stability levels between the two types of self-organized structures, we were able to synthesize a new type of molecule that only forms the former self-organized structure. By changing the mixing ratios between the original and new molecules, we succeeded for the first time in the world in controlling the timing at which an energetically stable self-organized structure begins to form. Controlling such timing is similar to the mechanism behind the biological clock in organisms from the viewpoint that in both cases, such time-controlling process is carried out by a network of molecules consisting of several chemical species.
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Ref: S. Ogi, T. Fukui, M. L. Jue, M. Takeuchi, K. Sugiyasu. “Kinetic control over pathway complexity in supramolecular polymerization through modulating the energy landscape by rational molecular design” Angew. Chem. Int. Ed.