Controlled Excited-State Dynamics and Enhanced Fluorescence Property of Tetrasulfone[9]helicene by a Simple Synthetic Process

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• 作者：Yuki Yamamoto ; Hayato Sakai ; Junpei Yuasa ; Yasuyuki Araki ; Takehiko Wada ; Tomo Sakanoue ; Taishi Takenobu ; Tsuyoshi Kawai ; Taku Hasobe
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：April 7, 2016
• 年：2016
• 卷：120
• 期：13
• 页码：7421-7427
• 全文大小：352K
• ISSN：1932-7455

文摘

Tetrasulfone[9]helicene (PTSH) was newly synthesized to improve and evaluate its fluorescence and excited-state dynamics through a single-step oxidation reaction of tetrathia[9]helicene (PTTH). In electrochemical measurements, the reduction potential of PTSH was shifted in a positive direction by approximately 1.0 V when compared to that of PTTH because of its electron-accepting sulfone units. The results of the electrochemical measurements agree with the energy levels calculated by density functional theory (DFT) methods and steady-state spectroscopic measurements. Furthermore, a significant enhancement of the absolute fluorescence quantum yield (Φ_FL) was achieved. The absolute fluorescence quantum yield of PTSH attained 0.27, which is approximately 10 times larger than that of PTTH (Φ_FL = 0.03). Such an enhancement of Φ_FL can be successfully explained by the corresponding kinetic comparison. The reason is mainly the increased energy gap ΔE_ST between the lowest singlet (S₁) and triplet (T₁) excited states. Finally, excellent circularly polarized luminescence of PTSH was also observed. The value of the anisotropy factor g_CPL was estimated to be 8.3 × 10^–4 in PTSH.