チラルの π-結合の二重螺旋アミニルジラジカルとトリプレットの基底状態
Haoxin Guo1, Joshua B Lovell2, Chan Shu1
1Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States.
Journal of the American Chemical Society
|March 19, 2024
まとめ
ビス[5]ディアザヘリケンの前駆体から高度に持続的なキラル高スピンディラジカルを合成した. この安定したダイラジカルには 三重の基本状態と 驚くべき持続性があり 新しい分子材料への道を開いています
科学分野:
- 有機化学
- 材料科学
- スペクトロスコーピー
背景:
- 高スピンダイラディカルは 分子磁気とスピントロニクスにとって不可欠です
- チラルのヘリケンは 独特の構造と電子特性を備えています
- 耐久性のある高スピンの有機分子を 開発することは依然として大きな課題です
研究 の 目的:
- 新種のキラル・ハイ・スピン・ディラディカルを 合成し特徴づけること
- ダイラジカルの耐久性と電子特性を調べる
- 材料科学におけるキラル・ディラディカルの潜在的な応用を探求する.
主な方法:
- キラルビス[5]ディアザヘリケンの前駆体合成.
- 電子パラマグネティック共振 (EPR) スペクトロスコーピーとSQUID磁気測定法による特徴化.
- エナティオメア濃縮のためのキラル超臨界流体染色学
- 理論的な洞察のための密度関数理論 (DFT) の計算.
主要な成果:
- 三重基底状態 (ΔEST ≈ 0.4 kcal mol−1) の中性高スピンダイラジカルが成功して合成された.
- ディラジカルは,半減期が最大6日であり,既知のアミニルラジカルを大幅に上回る例外的な持続性を示しています.
- エナチオメール濃縮の前駆体は,高いエナチオメール過量 (EE ≥ 94%) で得られた.
- テトラアミンの前駆体 (ΔG‡ = 43 ± 0. 01 kcal mol−1) とダイラジカル (ΔG‡ ≥ 26 kcal mol−1) の両方に高いラセミゼーションバリアが決定された.
結論:
- 合成されたキラル・ディラディカルは 前例のない安定性と 三重基底状態を示しています
- 効果的な3電子C-N結合を特徴とするユニークな電子構造は,その高い持続性に寄与する.
- この研究は,高度な磁気特性を有する有機材料の構成要素としてのキラル・ディアザヘリケンの可能性を強調しています.
関連する概念動画
01:07Radicals: Electronic Structure and Geometry
4.0K
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
4.0K
02:30Chirality at Nitrogen, Phosphorus, and Sulfur
5.7K
Chirality is most prevalent in carbon-based tetrahedral compounds, but this important facet of molecular symmetry extends to sp3-hybridized nitrogen, phosphorus and sulfur centers, including trivalent molecules with lone pairs. Here, the lone pair behaves as a functional group in addition to the other three substituents to form an analogous tetrahedral center that can be chiral.
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
A consequence of chirality is the need for enantiomeric resolution. While this is theoretically possible for all...
5.7K
01:33Radical Halogenation: Stereochemistry
3.7K
Stereochemistry is the study of the different spatial arrangements of atoms in a given molecule. The stereochemistry of radical halogenations can be understood from three different situations:
Halogenation to form a new chiral center:
Halogenation to form a new chiral center:
3.7K
01:19Structure of Amines
2.5K
The hybridized nitrogen atom in amines possesses a lone pair of electrons and is bound to three substituents with a bond angle of around 108°, which is less than the tetrahedral angle of 109.5°. However, the C–N–H bond angle is slightly larger at 112°, with a carbon–nitrogen bond length of 147 pm. This carbon–nitrogen bond length of of amines is longer than the carbon–oxygen bond of alcohols (143 pm) but shorter than alkanes’...
2.5K
02:25Chirality
24.2K
Chirality is a term that describes the lack of mirror symmetry in an object. In other words, chiral objects cannot be superposed on their mirror images. For example, our feet are chiral, as the mirror image of the left foot, the right foot, cannot be superposed on the left foot.
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
Chiral objects exhibit a sense of handedness when they interact with another chiral object. For example, our left foot can only fit in the left shoe and not in the right shoe. Achiral objects — objects that have...
24.2K
02:25Molecules with Multiple Chiral Centers
11.7K
Molecules that possess multiple chiral centers can afford a large number of stereoisomers. For instance, while some molecules like 2-butanol have one chiral center, defined as a tetrahedral carbon atom with four different substituents attached, several molecules like butane-2,3-diol have multiple chiral centers. A simple formula to predict the number of stereoisomers possible for a molecule with n chiral centers is 2n. However, there can be a lower number where some of the stereoisomers are...
11.7K