ピラミッド状の液晶の新シリーズにおけるメソモルフィズム,イソメリゼーション,およびダイナミクス
Herbert Zimmermann1, Victoria Bader, Raphy Poupko
1Max-Planck-Institut für Medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
Journal of the American Chemical Society
|December 19, 2002
まとめ
ノナ-アルカノイロキシトリベンゾサイクロノネン (CTV-n) のイソマーは,固い冠と柔軟なサドル形式で存在し,明確なメソモルフィック特性を表しています. 異体化ダイナミクスと相行動が特徴付けられ,柱状メソフェーズにおける温度依存変異と分子ダイナミクスが明らかになった.
科学分野:
- 超分子化学 超分子化学
- マテリアルサイエンス 材料科学
- 有機化学 オーガニック・ケミストリー
背景:
- ノナ-アルカノイロキシトリベンゾサイクロノネン (CTV-n) 化合物は,ユニークな構造的同位体性を表しています.
- 分子構造,ダイナミクス,およびメソモルフィック特性との関係を理解することは,材料設計において極めて重要です.
研究 の 目的:
- 溶液中のCTV-nイソマーのイソメリゼーション均衡とダイナミクスを調査する.
- 整った状態のCTV-n化合物のメゾモルフィック特性と相相性を特徴付ける.
- 冠との両方の同位体における柱状メソフェーズ内の分子ダイナミクスを解明する.
主な方法:
- 溶液中の高解像度1Hおよび13CNMRスペクトロスコーピーは,イソメリゼーションの運動と動態を研究します.
- X線 difraktion,光極化顕微鏡,および微分スキャニング熱計 (DSC) を用いてメソフェーズ特性を分析する.
- 13C固体MAS NMRは,メソフェーズにおける分子動態を調査する.
主要な成果:
- CTV-nイソマーは,異なるイソメリゼーション均衡と運動学を持つ安定した冠との形態として存在します.
- 両同位体とも六角形の柱状メソフェーズを形成し,十分な長さのサイドチェーン (n >= 4 または 5) を形成する.
- クラウンメソファゼは,ダイナミックな3倍分子ジャンプを示し,サドルメソファゼは,制限されたダイナミクスとライブラーションを示します.
結論:
- CTV-nのクラウンとセールイソマーは,複雑な解と固体状態の振る舞いを示します.
- 柱状メソフェーズにおける分子ダイナミクスは,形状に依存し,物質特性に影響を与えます.
- この研究は,ディスク性液晶における構造-性質関係に関する洞察を提供します.
関連する概念動画
02:22Structures of Solids
Solids in which the atoms, ions, or molecules are arranged in a definite repeating pattern are known as crystalline solids. Metals and ionic compounds typically form ordered, crystalline solids. A crystalline solid has a precise melting temperature because each atom or molecule of the same type is held in place with the same forces or energy. Amorphous solids or non-crystalline solids (or, sometimes, glasses) which lack an ordered internal structure and are randomly arranged. Substances that...
02:34Structural Isomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...
02:52Stereoisomerism
Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
02:33Stereoisomerism of Cyclic Compounds
In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...
01:10Recrystallization: Solid–Solution Equilibria
Recrystallization is a purification technique used to separate impurities from solid compounds. In this technique, no chemical reactions occur. Instead, it exploits physical properties only, specifically, the solubility differences between the desired compound and impurities, either at a single temperature or at different temperatures, and under other selected conditions. The solid-solution equilibrium (solubility equilibrium) of each component in the solution represents a binary phase...
01:29Determination of Crystal Structures
In the late 1800s, the revelation that light extended beyond visible wavelengths led to the discovery of X-rays by Wilhelm Roentgen. Recognized as high-energy electromagnetic radiation with short wavelengths, X-rays prompted exploration into their interaction with crystals. Max von Laue proposed in 1912 that the periodic arrangement of atoms, ions, or molecules in crystals would cause them to diffract X-rays, a hypothesis confirmed through experiments with copper sulfate and zinc sulfide...