Dative pi-bond engineering for the development of functional pi-conjugated materials

2020 Fiscal Year Final Research Report

• Project/Area Number: 19K22165
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 32:Physical chemistry, functional solid state chemistry, and related fields
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Shoji Yoshiaki 東京工業大学, 科学技術創成研究院, 准教授 (40525573)
• Project Period (FY): 2019-06-28 – 2021-03-31
• Keywords: 元素置換 / 供与性π結合 / シクロブタジエン / 芳香属性 / Baird芳香族性 / 燐光 / ホウ素 / 窒素

Outline of Final Research Achievements

In this study, we synthesized a BN-CBD derivative, in which the carbon-carbon bonds of cyclobutadiene (CBD) are replaced with isoelectronic and polarized boron-nitrogen bonds, and investigated the molecular and electronic structures as well as photophysical properties in detail. Theoretical calculations revealed that the B2N2 four-membered ring of the BN-CBD derivative has a planar rhombic structure in the ground state, but has a non-aromatic square structure in the triplet state. Interestingly, the BN-CBD derivative exhibits blue phosphorescence with a higher quantum yield than fluorescence emission even in solution at room temperature under degassed conditions. The presnt study sheds light on new aspects of BN-containing compounds and provides a new design guideline for photofunctional heterocyclic compounds.

Free Research Field

有機典型元素化学、超分子化学

Academic Significance and Societal Importance of the Research Achievements

本研究は、π共役化合物の基礎的な構造と性質にフォーカスしたものであるが、得られた成果は、励起三重項状態を効率的に生じさせたり、エネルギーの高い三重項状態を実現するための新しい指針を提供する。これらの性質は、π共役化合物を有機電子デバイスの部品として用いる上でも重要な要素である。本研究の知見を展開することで、高機能π共役化合物を合理的に設計するための新しい設計戦略へと繋がることが期待できる。