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鉄ポルフィリンによる酸素減少と,共振的に付着したペンデントフェノールとキノール

Asmita Singha¹, Arnab Mondal¹, Abhijit Nayek¹

¹School of Chemical Science, Indian Association for the Cultivation of Science, 2A Raja SC Mullick Road, Kolkata 700032, India.

Journal of the American Chemical Society

|December 15, 2020

まとめ

ペンダントフェノールまたはキノールグループを持つ鉄のポルフィーリンは,電気化学的に酸素を水に還元する. 反応機構は,陽子結合電子移転 (PCET) または水素原子移転 (HAT) のいずれかであり,特定のグループと熱力学に依存する.

科学分野:

バイオ有機化学
電気化学
カタリシス

背景:

フェノールとキノールは生物学的陽子と電子の移転に不可欠です
鉄のポルフィリンは酸素還元反応の重要な触媒である.
陽子結合電子移転 (PCET) や水素原子移転 (HAT) のような反応メカニズムを理解することは,触媒作用に不可欠です.

研究の目的:

ペンダントフェノールとキノールグループによる鉄ポルフィリンによる酸素減少を調査する.
これらの反応を制御するメカニズム的経路 (PCET vs. HAT) を解明する.
ペンダントグループが酸素減少の熱力学と運動学にどのように影響するかを決定する.

主な方法:

異質な電気化学を用いて酸素減少を研究した.
反応種を特定するために,有機溶液中の中間捕獲を使用した.
反応を制御する要因を理解するために熱力学的分析が行われました.

主要な成果:

ペンダントフェノールまたはキノール基を持つ鉄のポルフィリンは,4e-/4H+経路で効率的にO2をH2Oに還元する.
ペンダントフェノールグループは,FeIII-O2•−をFeIII-OOHに還元するためのPCETメカニズムを好みます.
ペンダントキノール群は,同じ還元ステップのためのHAT経路を好みます.
ヒドロキシル群がない場合,O2の還元は電子の移転に続いて陽子の移転を経由する.

結論:

鉄ポルフィリンによるO2減少のメカニズムは,PCETとHATの間で切り替えることで,ペンダントグループで調節できます.
ペンダントフェノル群からの水素結合相互作用は,中介物質を安定させることでPCETプロセスを強化する.
これらの発見は,酸素減少のための効率的な触媒を設計するための洞察を提供します.

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