Speakers


Presenter
Yoshimitsu SAGARA

Current position: Associate Professor

Institution /Faculty /Department : School of Material Science and Chemical Technology, Tokyo Institute of Technology


Bio

Yoshimitsu Sagara is an Associate Professor working on supramolecular materials at Department of Materials Science and Engineering in Tokyo Institute of Technology. He was born in 1981 in Takaoka city. He received his Ph.D. with Prof. Takashi Kato from the University of Tokyo in 2009. After working as a JSPS postdoctoral fellow in Kato’s group for one year, he joined Prof. Tetsuo Nagano’s group as a JSPS postdoctoral fellow in the University of Tokyo. Then, he joined Prof. Christoph Weder’s group as a JSPS Postdoctoral Fellow for Research Abroad in 2013. After that, he started to work as an Assistant Professor at Research Institute for Electronic Science (RIES) in Hokkaido University in 2015. He was appointed the present position in 2020. His research interests include various stimuli-responsive photofunctional materials based on supramolecular materials including liquid crystals, micelles, gels, and polymers and their practical applications. Especially, he is now focusing on a variety of mechanoresponsive luminescent materials.

Development of Rotaxane-based Supramolecular Mechanophores

Abstract

Mechanochromic polymer-based materials have attracted much attention because such materials can visualize material damage and structural failure. Insertion of so-called mechanophores into polymer is one of the most reliable way to achieve mechanochromic polymers. However, conventional mechanophores, which can be activated by mechanical stimuli-induced scission of covalent bonds, have several drawbacks because of the inherent mechanism. First, activation requires relatively strong power as activation involves cleavage of covalent bonds. Second, reverse reaction requires often higher energy, which results in poor reversibility. Furthermore, some mechanophores can be activated by thermal treatment or light irradiation as well as mechanical stimuli.


I will report supramolecular mechanophores to overcome those significant issues. A mechanically interlocked mechanophore composed of a fluorophore-carrying macrocycle and a dumbbell-shaped molecule containing a matching quencher was integrated into a polyurethane elastomer (Y. Sagara et al., J. Am. Chem. Soc. 2018, 140, 1584). Deformation of this polymer causes a fluorescence turn-on, due to the spatial separation of fluorophore and quencher. This process is specific, efficient, instantly reversible, and elicits an easily detectable optical signal that correlates with the applied force. We also achieved blue-, green-, orange-emissive rotaxane-based supramolecular mechanophores just by changing luminophores (Y. Sagara et al., ACS Cent. Sci. 2019, 5, 874).
 

Institute

School of Materials and Chemical Technology, Tokyo Institute of Technology