ペンデント・リレーは,ビピリジン基のCo-N2複合体による二酸化炭素還元時の選択性を強化する
Asa W Nichols1, Emma N Cook1, Yunqiao J Gan2
1Department of Chemistry, University of Virginia, McCormick Rd., PO Box 400319, Charlottesville, Virginia 22904-4319, United States.
Journal of the American Chemical Society
|August 12, 2021
まとめ
コバルト複合体は通常,ダイオキシンを過酸化水素に還元する. この研究では,選択性に影響を与える要因を調査するためにコバルト複合体を改変し,特定の構造変化が還元製品を変化させることが判明しました.
科学分野:
- 協調化学
- 電気触媒
- 有機合成
背景:
- コバルト-N2O2複合体は,ダイオキシゲン (O2) 還元のために一般的に使用される電気触媒です.
- これらの複合体は通常,過酸化水素 (H2O2) の生成に選択性を示す.
- 以前の研究で,水 (H2O) を生成する Co ((III) -N2O2 複合体を主製品として特定し,ユニークなメカニズム経路を示唆した.
研究 の 目的:
- コバルト・ヒドロペロキシドの中間物質のプロトネーション部位が製品選択性を決定するという仮説を検証する.
- 陽子化に影響を及ぼすように設計されたペンデントメトキシ (- OMe) グループを持つ新しい Co ((III) 複合体を合成し,研究する.
- 異なる溶媒と酸の条件で O2 還元選択性を支配するメカニズム的経路を解明する.
主な方法:
- ペンデントな陽子ドナー群を備えた新しい Co ((III) 複合体の合成.
- アセトニトリル (MeCN) で,異なる酸強度と還元剤を用いた電気触媒研究.
- コバルト超酸化物などの重要な中間物質を特定するための電子パラマグネティック共振 (EPR) スペクトロスコーピー.
主要な成果:
- 新しい Co ((III) 複合体は,酸強度と懸浮リレーの存在に依存する二重触媒体制を示した.
- MeCNでは,ペンデントリレーは主にH2O2の生産を促進し,以前のH2Oの選択性とは対照的です.
- EPR試験では,CO (III) スーパーオキシドの形成が確認され,O2反応性の強化が,未定の- OMe群で観察されました.
結論:
- 陽子ドナーの近さと性質は,コバルト触媒によるO2還元における反応経路と産物選択性に大きく影響する.
- 水から過酸化水素への選択性を変化させることができる.
- これらのメカニズム的な詳細を理解することは,選択的なO2変換のための高度な電気触媒の設計に不可欠です.
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