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分子内水素結合相互作用によって促進されるヘム-ペロキソ-銅複合体のスピン相互変換
Andrew W Schaefer1, Melanie A Ehudin2, David A Quist2
1Department of Chemistry , Stanford University , Stanford , California 94305 , United States.
Journal of the American Chemical Society
|March 6, 2019
まとめ
水素結合能力を持つ合成ペロキソブリッジ銅ヘム複合体は,可逆スピンクロスオーバー (SCO) を表している. 分子内H結合は低スピン状態を安定させ,電子構造に影響を与え,温度依存のスピン状態の相互変換を可能にします.
科学分野:
- バイオ有機化学
- 協調化学
- スペクトロスコーピー
背景:
- 合成ペロキシブリッジヘム銅複合体は,メタロ酵素活性部位の重要なモデルである.
- これらの複合体のスピン状態の移行を理解することは,生物学的メカニズムの解明の鍵です.
- 水素結合のような二次協調球の相互作用は,金属中心の性質を大幅に調節することができます.
研究 の 目的:
- ペロキソブリッジヘム銅複合体の電子構造と幾何学構造に対する分子内水素結合 (H結合) 能力の影響を調査する.
- これらの合成複合体のスピン状態とスピン・クロスオーバー (SCO) の可能性に対するH結合の影響を調査する.
- H結合と溶媒の相互作用が特定のスピン状態を安定させるメカニズムを解明する.
主な方法:
- 組み込まれたH結合機能を持つ高スピン (HS) ヘム銅 (L) 複合体の合成.
- 温度依存のスピン状態の変化と溶媒結合をモニターするための可変温度UV-VISおよび2H NMRスペクトロシー.
- 振動ラーマン (rR) スペクトロスコーピーと密度関数理論 (DFT) 分析により,H結合とスピン状態に関連した構造的および電子的変化を検出する.
主要な成果:
- ペロキソコアとの分子内H結合相互作用は,低スピン (LS) ヘム銅 (L) 構造を好み,可逆スピンクロスオーバー (SCO) を誘導する.
- 低温ではLS状態が好まれ,H結合はO−O結合を弱め,Fe−O結合を強め,知られているLS複合体と同等である.
- rRとDFTデータによって証明されるように,H結合はコアの幾何学的な変化を促進し,LS状態を安定させる溶媒結合を可能にします.
結論:
- 分子内H結合は,SCOを可能にする,過酸化橋渡されたヘム-銅複合体のスピン状態を制御する重要な要因である.
- H-ボンドは二次的調整球として作用し,LS状態を安定させるために電子構造と幾何学構造を調節する.
- これらの発見は,金属酵素における二次調整球の役割とスピン状態制御のメカニズムに関する基本的な洞察を提供します.
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