2022 Fiscal Year Final Research Report
Development of novel organic photo-reagents and organic photocatalysts driven by electron, proton and hydrogen atom transfers
| Project/Area Number |
19K05435
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 33010:Structural organic chemistry and physical organic chemistry-related
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| Research Institution | Niigata University |
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Principal Investigator |
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| Project Period (FY) |
2019-04-01 – 2023-03-31
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| Keywords | 有機光試薬・光触媒 / メタルフリー還元 / 電子・水素ドナー / ベンズイミダゾリン / ベンズイミダゾリウム / レドックス対 / DFT計算 / 過渡吸収測定 |
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| Outline of Final Research Achievements |
We have aimed to develop new photo-reagents as well as photocatalysts for reductive organic transformations based on the redox couples of benzimidazolines (BIH-R) and benzimidazoliums (BI+-R). These includes hydroxaryl substituted BIH (BIH-ArOH) / BI+ aryloxides (BI+-ArO-), triarylamine substituted couples (BIH-PhNAr2 / BI+-PhNAr2) and polycyclicaryl substituted couples (BIH-Ar / BI+-Ar). We discovered photo-oxygenation reactions promoted by BIH-R and molecular oxygen under the aerobic conditions. We designed the catalytic version of BIH-R photo-reagent protocol, and then successfully developed a protocol utilizing catalytic BI+-R and stoichiometric hydride donors in which BIH-R is generated in-situ. A novel photocatalytic system composed of BI+-ArO- and 2,2,6,6-tetramethylpiperidine N-oxyl was also developed. Noteworthy is that the long-lived charge-shifted state is generated via photoinduced intramolecular electron transfer of electron donor-acceptor dyad type BI+-PhNAr2.
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| Free Research Field |
有機化学
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| Academic Significance and Societal Importance of the Research Achievements |
光レドックス触媒による物質変換は，有機合成分野の一大潮流である。また，希少高価で残留懸念がある遷移金属触媒に対して，よりグリーンケミストリーに合致した有機分子触媒が注目されている。代表者が開拓したBIH-Rの光反応研究は幅広い分野に波及した。本研究では，未開拓のBI+-Rに基づく新規光レドックス触媒法を開発した。特にBI+-PhNAr2では，長寿命電荷シフト状態を経由する新規触媒機構を提案した。加えて，BI+-Rの特異な発光現象を発見した。この光レドックス特性や発光特性から，BI+-Rの人工光合成や有機発光デバイスへの応用も期待され，本研究成果の学術的意義および社会的意義は大きい。
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