Wakayama University · Faculty of Systems Engineering · 准教授

Research keywordsSynthetic Organic Chemistry・Heterocyclic Chemistry・Heteroatom Chemistry・ヘテロ原子化学・Organic Electroluminescent Materials・複素環化学・有機FET材料・有機EL材料・合成有機化学・ヘリセン

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• Spin dynamics of thiophene-fused π-systems with delayed emission2025 · Triplet excited states in organic molecules are generally optically inactive due to spin-forbidden transitions to the singlet ground state. Recent studies have extensively investigated triplet states to circumvent limitations imposed by spin statistics in organic light-emitting diodes. Room-temperature electrophosphorescence and electrofluorescence have previously been observed in thienyl-substituted phenazines without heavy metals; however, phosphorescence was absent when spin density was localized on the thiophene units, despite the expected heavy-atom effect from the sulfur atom. In this study, we investigate the spin dynamics of thiophene-fused π-systems lacking phenazine units to enable the effective utilization of triplet states in thiophene-containing π-systems. This investigation reveals delayed emission in the excited dimers of fused thiophenes, likely associated with triplet–triplet annihilation. Optical and EPR measurements, together with quantum chemical calculations, indicate that the fused thiophenes form head-to-tail dimers in both the ground and excited states.
• STM/TERS observation of M-type diphenyl[7]thiaheterohelicene on Ag(111)2024 · The chiral recognition of a self-assembled structure of enantiopure (M)-type 2,13-diphenyl[7]thiaheterohelicene ((M)-Ph-[7]TH) was investigated on a Ag(111) substrate by scanning tunnelling microscopy (STM) and tip-enhanced Raman spectroscopy (TERS).
• Chiral Recognition Mechanism of Two-Dimensional Self-Assembly Formed by [7]Thiaheterohelicene2023 · Changqing Ye, Takuma Hattori, Yuji Hamamoto, Pawel Krukowski, Kouji Inagaki, Akira Saito, Hideji Osuga, Yoshitada Morikawa, Yuji Kuwahara
• Study of stereochemical crystallization of racemic mixtures of [5] and [7] thiaheterohelicene molecules on Ag(111) surface by scanning tunneling microscopy and Raman scattering spectroscopy2022 · The crystallization of a racemic mixture of [5] and [7]thiaheterohelicene molecules into two-dimensional highly ordered molecular domains on a Ag(111) surface was investigated by scanning tunneling microscopy (STM) at 80 K. We observed that the crystallization of both thiaheterohelicene molecules on a Ag(111) surface was strongly affected by stereospecific interactions resulting from different numbers of aromatic rings incorporated into the helical skeletons of molecules. [5]Thiaheterohelicene molecules crystallized predominant into a few racemate polymorphic molecular domains, allowing us to obtain high-resolution STM images with the unambiguous identification of the absolute handedness of enantiomeric species. In contrast, the stereochemical chiral interactions among [7]thiaheterohelicene molecules led to the formation of one type of racemate molecular domain consisting of self-assembled zigzagged twin rows. X-ray photoelectron spectroscopy investigation strongly suggests weak interaction between thiaheterohelicene molecules and Ag(111) surface and lack of formation the S-Ag chemical bond. Surface-enhanced Raman spectroscopy combined with theoretical calculation based on a density functional theory was applied to the chemical verification of molecules adsorbed on a plasmonic silver surface for future tip-enhanced Raman spectroscopy.

• Synthesis of Novel Organic Electroluminescent Devices with High-brilliance and High-efficiency
• キラル認識プロセスの分子論的考察ー分子構造と光学非対称性からー
• Study on Synthesis and Properties of Helical Molecules
• らせん分子の合成とその機能に関する研究

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