旭硝子財団助成研究成果報告2023

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旭硝子財団　助成研究成果報告（2023）二原子炭素（C2）は，近年，基底状態で炭素間に四重結合性を持つと推定されている．C2は，星間物質や超高温（約3500度以上）で生じる炭素蒸気中に存在する活性種で，フラスコの中で温和な条件下に発生させることは困難と考えられてきた．他方，宇宙空間（星間雲や彗星など）には，二原子炭素C2が豊富に存在することが確認されており，近年C2由来のさまざまな炭素材料や，生命起源の候補分子の生成機構が予想されている．本研究では，各種C2 前駆体および反応条件を広く精査し，温和な条件下に発生する方法論の確立および，フラスコ内で化学的に発生させたC2がどのような分子に変化していくか，多面的に検証した．Diatomic carbon (C2) has recently been postulated to have quadruple bonding characters between carbons in its ground state; C2 is an active species that exists in carbon vapor produced in interstellar matters at very high temperatures (above ca. 3500 ℃), and it has been considered difficult to generate it under mild condi-tions in a flask. On the other hand, it has been confirmed that C2 is abundant in space (e.g., interstellar clouds, comets, etc.), and in recent years, various carbon materials derived from C2 and the formation mechanisms of candidate molecules originating from life have been predicted. In this study, we extensively explored various C2 precursors and reaction conditions, established a methodology for the generation of C2 under mild condi-tions, and examined from multiple perspectives how C2 chemically generated in a flask is transformed into molecules.幅広い分野での活用が期待されている近赤外光と，キラル特性を合わせ持つ材料の開発を目指した．我々が開発した近赤外色素であるボール型金属錯体は従来の平面構造を基とする近赤外色素と異なり，三次元にねじれた構造を持つため，置換基導入による非対称化が容易であると期待できる．そこで，大きな異方性が期待できる置換基を導入した錯体を設計，合成した結果，近赤外光との強い相互作用を保持しつつ，キラル異方性を持つことを明らかとした．これらの光学分割にも成功し，VCDスペクトルと理論計算から，絶対構造を決定することもできた．一連の化合物は不斉炭素原子を用いることなくキラル特性を発現できるため，誘導体の合成が容易かつ近赤外を活用できる新たな機能性色素となりうる．We aimed to develop a near-infrared (NIR) light-absorbing chiral material. NIR light is expected to be used in a wide range of fields. Whereas conventional NIR dyes and pigments are based on planar structures, the ball-shaped metal complexes have a three-dimensional twisted structure, which is expected to facilitate asymmetri-zation by introducing substituents. The complexes with substituents that are expected to have large anisotropy were designed and synthesized, and found that they have chiral properties with strong interaction with NIR light. The optical resolution of compounds was also successful, and their absolute structures could be deter-mined from VCD spectra and theoretical calculations. The series of compounds can develop chiral properties without chiral carbon atoms and thus can be novel functional dyes that can efficiently utilize NIR properties.44宮本　和範39Kazunori MIYAMOTO古山　渓行次世代近赤外キラル材料の開発40Taniyuki FURUYAMA三価の超原子価ヨウ素の脱離能を活用した二原子炭素の発生に基づく新規炭素同素体の創製，生成機構解明および生命起源分子の探索（2021採択）Synthesis of carbon allotropes and exploration of lifer’s first molecule based on the diatomic carbon generated from hypervalent iodine reagent(Project 2021)（2022採択）Development of Novel Near-infrared Activable Chiral Materials(Project 2022)