ペンダントアミンによる陽子の移動:水素の酸化のためのニッケル触媒における陽子の移動
Molly O'Hagan1, Wendy J Shaw, Simone Raugei
1Center for Molecular Electrocatalysis, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, USA.
Journal of the American Chemical Society
|May 21, 2011
まとめ
この研究は,ニッケル基の水素酸化電触媒における素早い分子内プロトン移動を明らかにしています. ペンダントアミンは,迅速な陽子移動を促進し,触媒効率と酵素機能に不可欠です.
科学分野:
- 無機化学 無機化学とは
- カタリシス カタリシス カタリシス
- バイオ物理化学 バイオ物理化学
背景:
- 陽子輸送は,多くの化学的および生物学的プロセスに不可欠です.
- 水素酸化電触媒は,エネルギー変換技術にとって不可欠です.
- プロトン伝送機構の理解は,効率的な触媒と酵素の設計に不可欠です.
研究 の 目的:
- ニッケル・ペンデント・アミン・コンプレックスにおける分子内プロトン移転を調査する.
- 陽子交換の動力学とエネルギー学を決定する.
- 水素酸化触媒のプロトン移転を促進するペンダントアミンの役割を明らかにする.
主な方法:
- 変化温度1DNMRスペクトル顕微鏡による可変温度1DNMRスペクトル顕微鏡
- 2D EXSY実験の2D EXSY実験について
- 密度関数理論 (DFT) の計算
- 分子ダイナミクス (MD) シミュレーション
主要な成果:
- Niとペンダントアミンの間の分子内プロトン交換が,特定のイソマーである[Ni(P(Cy) ((2) N(Bn) ((2) H) ((2))) ((2+) ]で観察されました.
- プロトン交換率の定数は,エンドポジションのアミンの25°Cでの10^4から10^5s^-1の範囲です.
- ΔG‡ = 11-12 kcal/molの陽子交換バリアを特定し,溶媒への依存は最小限にしました.
- 計算による研究が実験的発見を裏付け,速度制限のステップとして金属媒介型陽子移転と椅子からボートへのイソメリゼーションを示す.
結論:
- ニッケル触媒は高分子内プロトン移動性を示し,ペンダントアミンはプロトンリレーとして作用する.
- この移動性は,水素酸化触媒における陽子移動の加速に直接関係しています.
- 発見は,Ni-Feヒドロゲネーゼを含む同質な触媒と酵素における陽子の動きに関する洞察を提供します.
関連する概念動画
02:50Catalysis
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
01:27Catalysis
Catalysis influences the rate of chemical reactions by providing an alternative reaction pathway with lower activation energy. A catalyst speeds up a reaction, but it is not consumed during the process. The fundamental principle of catalysis is the ability of a catalyst to alter the reaction mechanism, often introducing a more efficient pathway than the uncatalyzed process.In a catalyzed reaction, the catalyst participates directly in the reaction mechanism. It interacts with reactants to form...
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:13Reduction of Alkenes: Catalytic Hydrogenation
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
01:29Preparation of Amines: Reduction of Oximes and Nitro Compounds
Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...