Highly Strained Compounds with Seven-Membered Rings: Construction of Unique Structures and Development of Functions

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K15528
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 33010:Structural organic chemistry and physical organic chemistry-related
• Research Institution: Hokkaido University
• Principal Investigator: Ishigaki Yusuke 北海道大学, 理学研究院, 准教授 (60776475)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 高歪化合物 / 酸化還元系 / 応答性分子 / ジカチオン / 光異性化 / 熱異性化 / X線結晶構造解析

Outline of Final Research Achievements

The carbon-carbon covalent bond is one of the most basic concept in organic chemistry. Bond length and bond angle among carbon atoms are nearly constant on the basis of the bond order and hybrid orbitals. On the other hand, highly strained compounds have attracted much attention with regard to their characteristic features. Regarding the C-C single bond, several attempts have been made to elongate the C-C single bond to gain new insight into the chemical bond and understand what happens at the limit of a bond. In addition, while the standard C=C double bond prefers a planar geometry, overcrowded ethylenes with bulky substituents can adopt folded and/or twisted forms due to the steric hindrance around the central C=C double bond.
In this study, focusing on highly strained π-electronic systems, a control of structures and physical properties based on extremely elongated C-C single bonds and highly strained C=C double bonds was accomplished.

Free Research Field

構造有機化学

Academic Significance and Societal Importance of the Research Achievements

共有結合は有機分子の基礎となる概念であり，結合長や結合角は通常決まった値を示す。一方，高度に歪んだ分子では標準値から逸脱した結合長をもち，それにより特異な性質が発現すると考えられてきたが，歪みによる不安定性のため，極限状態の結合をもつ分子の合成は困難であった。
本研究では，独自の分子設計により究極的に伸長した炭素－炭素単結合の柔軟性を発見し，その設計指針を単結合から二重結合へと拡張することで，構造及び物性の自在な制御を実現した。これらの成果は，有機化学分野で新たな潮流を示すものである。本研究成果は，共有結合の理解の深化に重要な知見を与え，持続可能な社会の実現に向けた足掛かりになると期待される。