Supramolecular Emitters

Functional organic dyes, which absorb and convert light or electrical energy into new forms, such as ultraviolet, visible, white or near-infrared light, are essential components of cutting-edge technologies. These include lighting and display devices, organic electroluminescent (EL) systems, materials that convert wavelengths for use in agriculture and horticulture, and bioimaging agents. In recent years, the development of such dyes has increasingly relied on computational chemistry techniques to predict properties and advanced organic synthesis strategies. However, a major challenge arises when these dyes are used in solid-state forms, such as powders, thin films or polymer matrices. In such environments, dye molecules tend to aggregate randomly, resulting in the loss of their intrinsic optical properties, including emission colour and intensity. In this study, we addressed this issue by using molecular self-assembly techniques to arrange dye molecules in a highly ordered manner at the nanometre scale. Treating multiple molecular components as puzzle pieces enabled us to develop a strategy for fabricating novel functional dyes through multicomponent co-crystallisation. Specifically, we present a crystalline material formed by the spontaneous self-assembly of three components: NDI (naphthalene diimide), TPFB (tris(pentafluorophenyl)borane), and a guest molecule. Depending on the identity of the guest, this material exhibits multicolour luminescence, demonstrating a versatile approach to solid-state functional dye design.

Multicomponent Molecular Puzzles for Photofunction Design: Emission Color Variation in Lewis Acid–Base Pair Crystals Coupled with Guest–to–Host Charge Transfer Excitation
Toshikazu Ono*, Manabu Sugimoto, Yoshio Hisaeda*
J. Am. Chem. Soc. 2015, 137(30), 9519-9522.
https://doi.org/10.1021/jacs.5b04178

Mechanochemistry is an emerging technique that significantly reduces the use of organic solvents in chemical reactions and has recently attracted considerable attention in the field of organic synthesis. In this study, we found that mechanochemical methods involving a mixer mill can effectively facilitate the self-assembly of multicomponent molecular systems involving three or more components. Using synchrotron radiation at SPring-8, we successfully performed in situ powder X-ray diffraction analysis and directly observed molecular self-assembly behaviour.

Multicomponent Crystals with Competing Intermolecular Interactions: In situ X-ray Diffraction and Luminescent Features Reveal Multimolecular Assembly of Solid-phase Reactions
Yoshio Yano, Hidetaka Kasai, Yanyan Zheng, Eiji Nishibori,* Yoshio Hisaeda*, Toshikazu Ono*
Angew. Chem. Int. Ed. 2022, e202203853.
https://onlinelibrary.wiley.com/doi/10.1002/anie.202203853