関連する実験動画
Updated: May 14, 2026
16:24
Controlling the Size, Shape and Stability of Supramolecular Polymers in Water
Published on: August 2, 2012
ナノスケールの原子炉におけるポリモルフ変異の立体化学制御
Qi Jiang1, Chunhua Hu, Michael D Ward
1Molecular Design Institute, Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003-6688, USA.
Journal of the American Chemical Society
|February 2, 2013
まとめ
ナノ孔で形成されたメタスタブルなβ-グリシンナノ結晶は,高湿度下ではアルファ-グリシンに変化する. アミノ酸補助物質は,重要な結晶面への水のアクセスを遮断することによって,この相変化を抑制することができます.
科学分野:
- マテリアルサイエンス 材料科学
- クリスタルグラフィーです.
- ナノテクノロジー ナノテクノロジー
背景:
- アミノ酸であるグリシンは,変異性のあるβ-グリシンと安定したアルファ-グリシンを含む複数の多形態形態で存在します.
- ナノコンフィネメントは結晶化経路とポリモルフの安定性を変化させることができます.
- アノド性アルミニウム酸化物 (AAO) ナノポールは,ナノ結晶形成を研究するための制御された環境を提供します.
研究 の 目的:
- AAOナノ孔におけるグリシンの結晶化を調査する.
- 異なる湿度下でのβ-グリシンナノ結晶の相変化行動を決定する.
- グリシン多形変異の制御におけるアミノ酸補助体の役割を調査する.
主な方法:
- 異なる直径のAAOナノポア内のグリシン結晶.
- 構造分析のための二次元X線微微微差分.
- 制御された湿度実験で相変化を誘導する.
- 結晶化中にラセミックおよびエナチオピュアアミノ酸補助剤の使用.
主要な成果:
- メタスタブルなβ-グリシンは,AAOナノポール<200nmで形成され, [010]軸は孔方向に整列しています.
- ベータ-グリシンナノ結晶は,相対湿度90%でアルファ-グリシンに変換され, [010]軸の方向転換が行われます.
- ラセミアミノ酸補助物質は,{010}面に選択的に結合することによって,βからαへの移行を抑制した.
- エナチオピュア補助剤は移行を妨げず,ステレオ選択的結合と水へのアクセスの大切さを示した.
結論:
- AAOナノポールのベータグリシンの[010]軸の方向性は,ポリマーモノリットのそれと似ています.
- 高湿度でベータグリシンからアルファグリシンへの相変化が起こり,分子の重点を大きく変える.
- アミノ酸補助物質は結晶化修正剤として作用し,水分子をステリカルに阻害することで相変遷を防ぐことができる.
- アミノ酸の特定の結晶面へのステレオ選択的結合は,ナノ限られた環境におけるグリシン多形態化を制御するために重要である.
関連する概念動画
02:23SN2 Reaction: Stereochemistry
In an SN2 reaction, the nucleophilic attack on the substrate and departure of the leaving group occurs simultaneously through a transition state. As the nucleophile approaches the substrate from the back-side, the configuration of the substrate carbon changes from tetrahedral to trigonal bipyramidal and then back to tetrahedral, leading to an inversion in the configuration of the product.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
If the substrate is an achiral molecule at the α-carbon, the inversion of configuration is not observed.
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta catalyst, high molecular...
01:18Bioreactor Controls-II
In aerobic fermentations, oxygen is vital for microbial growth and metabolite production. Since air comprises only about 20% oxygen and the gas is poorly soluble in water—just 9 ppm at 20°C—supplying sufficient oxygen becomes a critical challenge, especially in high-demand processes like yeast growth or citric acid production. Even a fully saturated broth may offer only a few seconds of oxygen availability.To address this, sterile or scrubbed air is introduced into the fermentor via a sparger...
02:17Regioselectivity of Electrophilic Additions to Alkenes: Markovnikov's Rule
If a set of reactants can yield multiple constitutional isomers, but one of the isomers is obtained as the major product, the reaction is said to be regioselective. In such reactions, bond formation or breaking is favored at one reaction site over others.
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
The hydrohalogenation of an unsymmetrical alkene can yield two haloalkane products, depending on which vinylic carbon takes up the halogen. However, one product usually predominates, where hydrogen adds to the vinylic carbon bearing the...
01:28Bioreactor Controls-I
Maintaining optimal conditions within fermenters is essential for maximizing microbial productivity and ensuring process efficiency. This lesson focuses on key parameters—temperature, foam, pH, carbon dioxide, oxygen, and pressure—and their precise measurement and control strategies in fermentation systems.Temperature ControlTemperature regulation is critical due to the exothermic nature of many fermentation processes. In small laboratory fermenters, temperature is commonly monitored using...