Kohei Okino, Master's student, Yuki Inoue, Daisuke Sakamaki, Professor Shuhei Seki, and Shota Hira, a third-year student at Nada High School, are a kind of radical molecule (a molecule with unpaired electrons). It was discovered that the binding mode between) can be modulated by the design of the molecular structure.
Mr. Taira is a student participating in the Kyoto University high school connection program "ELCAS".This unique research result brought about by the high school connection program was published in the online breaking news of the German chemistry magazine "Angewandte Chemie" on November 2017, 11.
Covalent bonds that break or connect due to external stimuli such as heat or light are called dynamic covalent bonds, and because chemical bonds can be reversibly rearranged, highly recyclable materials and self-repairing scratches. It is expected to be applied to self-healing materials.
In this study, we focus on dicyanomethyl radicals among the molecules with dynamic covalent bonds.This radical has the problems that it is in an equilibrium state with a large bias toward a state in which two molecules are connected (dimer / dimer), and that it is easily decomposed by a side reaction and does not return to the original molecule. Was introduced to stabilize it.
The research group synthesized radical molecules with three different amino groups and investigated the properties of each.Then, it was found that two of the three types formed a sigma-dimer and the other formed a pie-dimer during dimerization.That is, it was clarified that the binding method of the two molecules can take a completely different mode due to a slight difference in the molecular structure.
This finding provides a guideline for controlling the strength of certain covalent bonds by molecular design, and further progress in radical covalent bond network research is expected.
Paper information:[Angewandte Chemie] The Divergent Dimerization Behavior of N-Substituted Dicyanomethyl Radicals: Dynamically Stabilized versus Stable Radicals
