We participated in the 31st Organic Crystal Symposium held at Osaka University from November 1st to 3rd.
Korenaga-kun, Hattori-kun, and Okada-kun presented their latest research results.
Maeda Sensei visited our University to have a 2-day class and the lecture.
Before the break for preparing the examination, we went to Izakaya.
Our group develops stimuli-responsive molecular-based materials, such as crystals, liquid crystals, organogels and etc. We try to elucidate so far unknown responses of such materials and provide novel functionality of molecules.
Molecular-based materials exhibiting stimuli-responsivity
Molecular crystals or liquid crystals often show properties and functionality different from its individual molecule itself. This is caused by the neighboring molecules within the assembled materials which are connected through various intermolecular interactions. This indicates that the molecular-based materials can show properties/functionalities based on assembled states. Upon applying external stimulations to such materials, such as temperature change, photoirradiation and mechanical stimulations, the assembled states/molecular arrangements can change. As a result, these molecular-based materials exhibit various responses, i.e., property changes and mechanical movement.
Bridging the gap between macroscopic externals stimulation and microscopic molecular arrangement
We have reported that the molecular-based materials exhibiting emission color changes, electronic conductivity changes, and mechanical movements upon applying mechanical stimulation. These stimuli-responses are caused by the “macroscopic” mechanical force by means of a spatula or a pestle/mortar, which leading to changes in “macroscopic” molecular arrangements and patterns of intermolecular interactions. Our group tries to elucidate precise molecular arrangements within the crystals/liquid crystals to identify the effect of external stimulation, bridging the gap between macro- and microscopic information.
D. Korenaga, T. Seki,
Chem. Eur. J., 2023, in press
C. Feng, T. Seki, S. Sakamoto, T. Sasaki, S. Takamizawa, H. Ito,
Chem. Sci., 2022, 13, 9544–9551
Shape-memory materials can be mechanically deformed and subsequently reverse the deformation upon changing the temperature. Shape-memory materials have attracted considerable attention for basic research and industrial applications, and polymer and alloy shape-memory materials have been well studied; however, it is formidably challenging to develop functional shape-memory materials, such as materials with multi-stage and anisotropic shape changes and shape changes accompanied by changes in color and light emission. Here, we found a reversible multi-stage shape-changing effect after mechanical deformation in a molecular crystal induced by multi-step thermal phase transitions with reversible shape changes and luminescence-color changes. Using single-crystal structure and thermal analyses as well as mechanical property measurements, we found that the reversible multi-stage shape-changing effect was achieved by a combination of a twinning deformation and multi-step thermal phase transitions. The changes in the crystal shape and luminescence suggest novel strategies for imparting known shape-memory materials with additional functionalities.
T. Seki, N. Hoshino, Y. Suzuki, S. Hayashi,
CrystEngComm, 2021, 23, 5686–5696
K. Kato, T. Seki, H. Ito,
Inorg. Chem, 2021, 60, 10849–10856