ITO LABORATORY

Research
Directions

OUR APPROACH

From Original Molecules to New Functions

Organic molecules can adopt an enormous variety of structures. Using the tools of synthetic organic chemistry, we can design and synthesize molecules that do not exist in nature.

Our research focuses on creating original molecules for the first time and uncovering new phenomena and functions that arise from their structures. By precisely designing and controlling molecular structures, electronic states, and assemblies, we aim to develop advanced luminescent, chiral, and porous materials.

01

LUMINESCENCE

Stimuli-Responsive Luminescence

Mechanochromic Luminescence (MCL)

Organic luminophores can convert absorbed energy into light, and their emission properties are highly sensitive to molecular structure and solid-state organization.

We discovered newly synthesized molecules that exhibit mechanochromic luminescence (MCL), in which solid-state emission color changes reversibly under mechanical stimuli such as grinding. Building on these systems, we investigate structure–property relationships in MCL and establish molecular-design principles for controlling the magnitude, direction, and recovery of the emission response.

Donor–Acceptor Systems

We develop donor–acceptor molecules in which electron-donating heterocycles are directly linked to an electron-accepting benzothiadiazole ring. Indole-donor derivatives exhibit MCL with spontaneous recovery of their emission color at room temperature. By changing the donor unit, we have achieved MCL with blue-shifted emission upon rubbing, as well as two-step emission-color changes depending on the strength of mechanical stimulation. More recently, we have extended this concept to molecules whose emission color recovers in response to water vapor.

Mechanochromic luminescence of donor–acceptor molecules

Two-Component Systems

Most conventional MCL materials are single-component crystals. We are studying how to rationally control MCL behavior by combining an MCL molecule with a second luminophore.

By creating segregated crystals in which two luminophores crystallize independently, we achieved both a greatly expanded emission-wavelength shift upon grinding and spontaneous recovery of the emission color. We have also expanded the emission-wavelength change by forming mixed crystals in which a very small amount of a guest molecule is incorporated into a host crystal.

Two-component mechanochromic luminescence systems
Show selected publications & reviewsHide selected publications & reviews
  1. Ito, S.* Chem. Lett. 2021, 50, 649–660 (Invited Review, Open Access).
  2. Ito, S.* J. Photochem. Photobiol., C 2022, 51, 100481 (Invited Review).
  3. Ito, S.* CrystEngComm 2022, 24, 1112–1126 (Invited Review).
  4. Ito, S.* Bull. Chem. Soc. Jpn. 2026, 99, uoag119 (Invited Review, Open Access).
  5. Ito, S.*; Yamada, T.; Taguchi, T.; Yamaguchi, Y.; Asami, M. Chem. Asian J. 2016, 11, 1963–1970 (Link).
  6. Ito, S.*; Taguchi, T.; Yamada, T.; Ubukata, T.; Yamaguchi, Y.; Asami, M. RSC Adv. 2017, 7, 16953–16962 (Open Access).
  7. Nagai, S.; Yamashita, M.; Tachikawa, T.*; Ubukata, T.; Asami, M.; Ito, S.* J. Mater. Chem. C 2019, 7, 4988–4998 (Link).
  8. Chen, H.; Kato, K.; Imai, Y.*; Ito, S.* Adv. Opt. Mater. 2026, 14, e71360 (Open Access, Press Release).
  9. Ikeya, M.; Katada, G.; Ito, S.* Chem. Commun. 2019, 55, 12296–12299 (Link).
  10. Ito, S.*; Sekine, R.; Munakata, M.; Yamashita, M.; Tachikawa, T.* Chem. Eur. J. 2021, 27, 13982–13990 (Read Only Link).
  11. Yoshida, R.; Tachikawa, T.*; Ito, S.* Chem. Commun. 2022, 58, 6781–6784 (Link).
  12. Furukawa, H.; Tachikawa, T.; Ito, S.* Chem. Commun. 2026, 62, 8008–8012 (Link).
02

CHIRALITY

Chemistry of Chiral Molecules

Asymmetric Synthesis

Chirality can strongly influence molecular recognition, optical properties, and biological activity. We therefore develop stereoselective synthetic methods as a foundation for functional chiral molecules.

We established a highly stereoselective “double asymmetric addition” that constructs two stereocenters in a single operation, providing efficient access to chiral diamines. We use this strategy to create chiral molecules with new functions.

Asymmetric synthesis of chiral molecules

Circularly Polarized Luminescence (CPL)

Chiral luminescent molecules can exhibit circularly polarized luminescence (CPL), in which right- and left-circularly polarized emission have unequal intensities. We were among the first to realize a new type of CPL switching in which both the handedness and wavelength of CPL can be switched while the visually observed emission color remains nearly unchanged. We are now extending this concept to solid-state materials, achieving reversible CPL changes driven by two different mechanical stimuli and chiral molecular crystals that retain efficient CPL even after amorphization.

Circularly polarized luminescence and CPL switching of chiral molecules
Show selected publicationsHide selected publications
  1. Ito, S.*; Ikeda, K.; Asami, M.* Chem. Lett. 2016, 45, 1379–1381 (Link).
  2. Ito, S.*; Ikeda, K.; Nakanishi, S.; Imai, Y.*; Asami, M.* Chem. Commun. 2017, 53, 6323–6326 (Link, Press Release).
  3. Ito, S.*; Sekine, R.; Munakata, M.; Asami, M.; Tachikawa, T.; Kaji, D.; Mishima, K.; Imai, Y.* ChemPhotoChem 2021, 5, 920–925 (Read Only Link).
  4. Murata, H.; Suzuki, S.; Terakubo, K.; Imai, Y.*; Ito, S.* Chem. Asian J. 2024, 19, e202400293 (Open Access).
  5. Ito, S.*; Wakiyama, S.; Chen, H.; Abekura, M.; Uekusa, H.; Ikemura, R.; Imai, Y.* Angew. Chem. Int. Ed. 2025, 64, e202422913 (Open Access, Press Release).
03

ASSEMBLY

Molecular Assembly

Dynamic Covalent Chemistry

Conventional covalent bonds, once formed, do not readily break. Dynamic covalent bonds, however, can repeatedly form and break under specific conditions. This reversibility allows molecules to reconnect many times and spontaneously converge toward stable structures. We use this behavior to construct macrocycles and explore their functions.

Molecular assembly using dynamic covalent bonds

Quasiracemic Assembly

When two molecules that are not exact mirror images but have very similar shapes—so-called quasiracemates—are crystallized together, they can sometimes form regular, ordered arrangements. We exploit quasiracemic assembly to create organic molecular crystals with unusual functions. For example, self-assembly of quasiracemic dialdehydes and diamines into macrocyclic imine crystals enabled us to form two types of one-dimensional pores with different sizes within a single crystal.

Two types of one-dimensional pores formed by quasiracemic self-assembly
Show selected publicationsHide selected publications
  1. Ito, S.; Ono, K.; Iwasawa, N.* J. Am. Chem. Soc. 2012, 134, 13962–13965 (Link).
  2. Ito, S.; Takata, H.; Ono, K.; Iwasawa, N.* Angew. Chem. Int. Ed. 2013, 52, 11045–11048 (Link).
  3. Ito, S.; Ono, K.; Johmoto, K.; Uekusa, H.; Iwasawa, N.* Chem. Sci. 2016, 7, 5765–5769 (Open Access).
  4. Ito, S.*; Okada, S.; Sue, R.; Asami, M.* Chem. Lett. 2018, 47, 340–343 (Link).
  5. Kimoto, M.; Sugiyama, S.; Kumano, K.; Inagaki, S.; Ito, S.* J. Am. Chem. Soc. 2024, 146, 17559–17565 (Open Access, Press Release).
  6. Ito, S.*; Fukuhara, K.; Arakawa, N.; Suzuki, S.; Imai, Y.* Chem. Eur. J. 2025, 31, e202501677 (Open Access).
  7. Zhao, Y.; Ito, S.* Bull. Chem. Soc. Jpn. 2026, 99, uoag025 (Link).