Suguru Ito

Graduate School of Engineering Science, Yokohama National University
Associate Professor
A02

Research AreasSynthetic Organic Chemistry, Organic Photochemistry, Supramolecular Chemistry
Participating Group (2020-2021)

Rational Creation of Mechanical-Stimuli-Responsive Soft Crystals and Sophistication of Quantitative Analytical Method

Keywords
Soft Crystal, Mechanochromic Luminescence, Organic Fluorophores, Multi-color Emission, Intermolecular Interaction, Tribology, Solid-state NMR
Co-Researcher
Co-Researcher: Ken Nakano(Graduate School of Environment and Information Sciences, Yokohama National University, Professor)
Co-Researcher: Izuru Kawamura(Graduate School of Engineering Science, Yokohama National University, Associate Professor)

Research Outline

Mechanochromic luminescence, that can change the emission properties in response to mechanical stimuli such as grinding, is one of the typical stimuli-responsive behaviors exhibited by soft crystals. In the previous work, this researcher has succeeded in developing an apparatus that can quantitatively evaluate the responsiveness of soft crystals to mechanical stimuli. In addition, a new design guideline for mechanochromically luminescent materials has been established based on the creation of two-component organic soft crystals.

In this study, this researcher will realize the development of structural motifs and mechanistic analyses of soft crystals. Specifically, (1) a rational method to control the mechanical-stimuli-responsiveness will be established by forming complexes between novel luminescent host molecules and guest molecules. (2) Energy diagrams of mechanochromic luminescence will be clarified by the quantitative analysis of the responsiveness of soft crystals to mechanical stimuli. In addition, the quantitative analysis of mechanical-stimuli-responsive behaviors of various soft crystals will be examined thorough collaborative researches, which will lead to a comprehensive understanding of the responsiveness of soft crystals to mechanical stimuli.

Mechanochromic Luminescence of Two-Component Organic Soft Crystal
Creation of Host-Guest Soft Crystals
Participating Group (2018-2019)

Creation of Multi-color Emissive Organic Soft Crystals and Quantitative Analysis of Mechanical Stimuli-responsive Property

Keywords
Soft Crystal, Mechanochromic Luminescence, Organic Fluorophores, Multi-color Emission, Intermolecular Interaction, Tribology, Solid-state NMR
Co-Researcher
Co-Researcher: Ken Nakano (Graduate School of Environment and Information Sciences, Yokohama National University, Professor)
Co-Researcher: Izuru Kawamura (Graduate School of Engineering Science, Yokohama National, Associate Professor)

Research Outline

Soft crystals that can change their emission colors in response to mechanical stimuli such as “grinding” are a part of the central research subjects of this area. The principal investigator has already succeeded in the development of mechanochromic luminescent organic soft crystals that exhibit “self-recovery of changed emission color” or “two-step emission color change in response to the strength of grinding force”. In this study, we establish a quantitative analysis method for the strength of mechanical stimuli required for the emission color change and a new creation method for the multi-color emissive mechanochromic luminescent soft crystals. These studies would provide mechanistic insights and novel motifs of mechanochromic luminescent organic soft crystals. Specifically, we will work on (1) the quantification of “grinding force” by a device designed and developed by ourselves, and (2) the creation of multi-color emissive soft crystals by utilizing intermolecular interactions of different molecules. We also aim to comprehensively understand this phenomenon by the quantification of the strength of mechanical stimuli required for other soft crystals through collaborative researches.

Two-step Mechanochromic Luminescent Soft Crystal
New Method for the Creation of Multi-color Emissive Soft Crystals

Publications

Academic papers/reviewed

A02-14

  1. "Tunable Mechanochromic Luminescence of 2-Alkyl-4-(pyren-1-yl)thiophenes: Controlling the Self-recovering Properties and the Range of Chromism" M. Ikeya, G. Katada and S. Ito, Chemical Communications, 2019, 55(82), 12296–12299.
  2. "Switching the Direction of Mechano-responsive Emission Color Change of Triphenylimidazolylbenzothiadiazole" S. Ito, S. Nagai, T. Ubukata and M. Asami, Chemistry Letters, 2019, 48(12), 1492–1495.
  3. "Sequential Halochromic/mechanochromic Luminescence of Pyridyl-substituted Solid-state Emissive Dyes: Thermally Controlled Stepwise Recovery of the Original Emission Color" S. Ito, C. Nishimoto and S. Nagai, CrystEngComm, 2019, 21(38), 5685–5854.
  4. "Efficient and Versatile Mechanochromic Luminescence of Phenanthroimidazolylbenzothiadiazoles: Tricolor Switching and Directional Control over the Chromism" S. Nagai, M. Yamashita, T. Tachikawa, T. Ubukata, M. Asami, S. Ito, Journal of Materials Chemistry C, 2019, 7, 4988-4998.
  5. "Tricolor mechanochromic luminescence of an organic two-component dye: visualization of a crystalline state and two amorphous states" S. Ito, G. Katada, T. Taguchi, I. Kawamura, T. Ubukata, M. Asami, CrystEngComm, 2019, 21, 53-59.

Related Website(s)
Contact
suguru-ito[at]ynu.ac.jp