関連する実験動画

Updated: Jul 5, 2026

Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors

Effect of Bending on the Electrical Characteristics of Flexible Organic Single Crystal-based Field-effect Transistors

Published on: November 7, 2016

電子効果は,非機能化されたアリル置換アルケンの非対称な水素化のメカニズムを制御する

Yubo Fan¹, Xiuhua Cui, Kevin Burgess

¹Department of Chemistry, Texas A & M University, Box 30012, College Station, TX 77842-3012, USA.

Journal of the American Chemical Society

|December 23, 2004

まとめ

密度関数理論の計算は,イリジウム複合体がアルケンの非対称な水素化をどのように触媒化するかを明らかにします. リガンドのアダマンチル群とのステリック相互作用は,主にこれらの反応におけるエナチオ表面の選択性を決定する.

科学分野:

有機金属化学有機金属化学
アシンメトリック・カタリシス
コンピューティング・ケミストリー

背景:

非対称な水素化は,キラル分子の合成に不可欠である.
N-ヘテロサイクルカルベンリガンドを含むイリジウム複合体は,効果的な触媒である.
反応機構と選択性決定因子の理解は,触媒設計の鍵となる.

研究の目的:

イリジウムイミダゾリリジンオクサゾリン複合体によって触媒化されたアルケンの非対称な水素化のメカニズムを解明する.
この触媒システムにおけるエナチオ表面選択性を支配する要因を調査する.
実験的観測に対する計算上の予測を検証する.

主な方法:

密度関数理論 (DFT) の計算は,PBEとB3LYPの関数を使用しています.
アルケンの調整,移動性挿入,および製品放出のステップのモデリング.
ステレオ選択性に影響を与えるステリックおよび電子的要因の分析.

主要な成果:

アルケンの協調は,好ましくは,カルベンのリガンドのトランスに発生します.
水素化の過程は,H2と水素移転による連続反応を経由して進みます.
リガンドのアダマンチル群とのステリック相互作用は,三置換アルケンのエナンチオ表面選択性の主要な駆動因子である.

結論:

DFTモデルは,実験的に観察されたエナチオ選択性を正確に予測します.
この研究は,イリジウム触媒による非対称な水素化のメカニズム的理解を提供します.
リガンドの設計,特にステリック・バルクは,エナチオ選択性の制御に極めて重要です.

さらに関連する動画

Electric-field Control of Electronic States in WS2 Nanodevices by Electrolyte Gating

Electric-field Control of Electronic States in WS₂ Nanodevices by Electrolyte Gating

Published on: April 12, 2018

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VOx

In Situ Transmission Electron Microscopy with Biasing and Fabrication of Asymmetric Crossbars Based on Mixed-Phased a-VO_x

Published on: May 13, 2020

関連する概念動画

Allosteric Regulation

Allosteric Regulation

Allosteric regulation of enzymes occurs when the binding of an effector molecule to a site that is different from the active site causes a change in the enzymatic activity. This alternate site is called an allosteric site, and an enzyme can contain more than one of these sites. Allosteric regulation can either be positive or negative, resulting in an increase or decrease in enzyme activity. Most enzymes that display allosteric regulation are metabolic enzymes involved in the degradation or...

Biasing of Metal-Semiconductor Junctions

Biasing of Metal-Semiconductor Junctions

Biasing metal-semiconductor junctions involves applying a voltage across the junction. Specifically, the metal is connected to a voltage source, while the semiconductor is grounded. This technique is essential for controlling the direction and magnitude of current flow in electronic devices, including diodes, transistors, and photovoltaic cells.
In Schottky junctions, where the semiconductor is n-type, applying a positive voltage to the metal relative to the semiconductor reduces its Fermi...

Bipolar Junction Transistor

Bipolar Junction Transistor

Bipolar Junction Transistors (BJTs) are essential elements in electronic circuits, playing a crucial role in the functionality of amplifiers, memories, and microprocessors. These transistors can be designed as NPN or PNP based on their doping patterns. They consist of three layers: the emitter, base, and collector. The configuration of these layers and their respective doping levels—with N-type or P-type impurities—define the transistor's type and its operational characteristics.
The structure...

Field Effect Transistor

Field Effect Transistor

Field-effect transistors (FETs) are integral to electronic circuits and distinguished by their three-terminal setup: the gate, drain, and source. These transistors operate as unipolar devices, which utilize either electrons or holes as charge carriers, in contrast to bipolar transistors, which use both types of carriers. The primary function of the FET is to modulate the flow of these carriers from the source to the drain through a channel. The voltage difference between the gate and source...

BJT Amplifiers

BJT Amplifiers

Bipolar Junction Transistors (BJTs) are pivotal components in amplifier circuits, functioning as voltage-controlled current sources in their active region. This characteristic allows them to efficiently control the collector current through variations in the base-emitter voltage. Essentially, BJTs amplify power due to their ability to take a weak input signal and output a much stronger signal.
In BJT amplifier configurations, particularly in common-emitter setups, the transistor's role extends...

Biasing of FET

Biasing of FET

Biasing a Junction Field Effect Transistor (JFET) is crucial for setting operational parameters and ensuring efficient functioning in electronic circuits. JFETs are characterized by using a single carrier type in N-channel or P-channel configurations, where the channel is surrounded by PN junctions. These junctions are central to the device's ability to control current flow.
In an N-channel JFET, the structure consists of N-type material forming the channel on a P-type substrate, with the gate...