四重ヘリケンの合成と構造的特徴:ヘリケンの反発の蓄積によって可能になった高度に歪んだ π システム

Takao Fujikawa¹, Yasutomo Segawa¹, Kenichiro Itami¹

¹Graduate School of Science, ‡JST, ERATO, Itami Molecular Nanocarbon Project, and §Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University , Nagoya 464-8602, Japan.

Journal of the American Chemical Society

|February 27, 2016

まとめ

四重ヘリケーンが合成され独特のプロペラとの形が明らかになりました彼らの独特の幾何学は,電子特性と異体化経路に影響を与え,幾何学に依存する電子状態を示しています.

科学分野:

有機化学
超分子化学
材料科学

背景:

ヘリケンは独特の螺旋構造を持つキラルな芳香炭化水素である.
ポリサイクルアロマティック炭化水素のヘリシティを制御することは,新しい材料の開発に不可欠です.

研究の目的:

ディジア[6]ヘリケーンと[5]ヘリケーン基構造を用いた四重ヘリケーンを合成し,特徴づけること.
分子幾何学,光物理,電気化学の性質の関係を調査する.
ステレオイソメリゼーション経路と運動を明らかにする.

主な方法:

合成のための制御されたショル反応.
構造の決定のためのX線結晶学.
光物理学と電気化学の研究 (UV-Vis,光,サイクル電圧測定)
密度関数理論 (DFT) の計算
(1) 運動研究のためのH NMRと円形の二重化.

主要な成果:

9つのステレオアイソマーを持つ四重ヘリケーンを合成しました.
異なるプロペラ形 (QH-A) とサドル形 (QH-B) の構造をX線結晶学で決定した.
QH-Bは,ステリック反発による極端な回転 (69.5°) を示した.
観測された幾何学に依存する電子特性:HOMO-LUMOギャップの拡大とQH-BのHOMOの低下.
イソメリゼーション経路と逆転障壁に影響を与える要因を特定した.

結論:

分子幾何学は四重ヘリケンの電子状態に大きく影響する.
この研究は,複雑な螺旋システムの合成,特徴化,および行動に関する洞察を提供します.
ステレオイソメリゼーションを理解することは,ヘリケーンベースの機能的材料を設計する上で鍵となる.

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