Synthesis and properties of stable radicals derived from azulene-based chiral helicene compounds

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K05041
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 33010:Structural organic chemistry and physical organic chemistry-related
• Research Institution: Kyushu University
• Principal Investigator: Tani Fumito 九州大学, 先導物質化学研究所, 准教授 (80281195)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: アズレン / ヘリセン / ラジカル / 電子スピン / 不斉 / ピロール / パイ電子 / 酸化

Outline of Final Research Achievements

Radical species of optically active helicenes are of interest as chemical species having electron spins on a chiral π-electron framework, but there are very few examples of stable helicene radicals. On the other hand, azulene, a structural isomer of naphthalene, has characteristic properties derived from its polarized π-electron system, and its dimer 1,1'-biazulene gives relatively stable cation radical species. AIBPyr-Mes, a derivative of electron-donating pyrrole sterically protected at the α-position by a mesityl group and a helicene of 1,1'-biazulene moiety, was synthesized. The helical structure was confirmed by X-ray crystallography and optical resolution was successfully achieved. The formation and stability of cation radicals were confirmed by chemical oxidant reactions, and this radical was successfully isolated.

Free Research Field

構造有機化学

Academic Significance and Societal Importance of the Research Achievements

単一の分子内にキラリティと電子スピンの両方を有する光学活性ヘリセンのラジカルは基礎科学および応用の両方の観点から非常に興味深い化学種でありながら，不安定であるために，その報告例は極めて限られていた。本研究では，この課題の解決に取り組み、1,1'-ビアズレン骨格から成るヘリセンと電子供与性ピロールが融合した新しい化合物を合成した。その詳細な分子構造を解明し、さらに安定なカチオンラジカル種を得ることにも成功した。ヘリセン化合物の安定ラジカル種を得るための有用な知見を明らかにした点に学術的な意義があり、機能性材料としての応用展開へとつながる成果である。