関連する実験動画
Updated: Jul 15, 2026

10:35
Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals
Published on: May 29, 2018
分子コンパスと極旋回子付のジロスコープ:結晶形の合成と特徴づけ
Zaira Dominguez1, Tinh-A V Khuong, Hung Dang
1Department of Chemistry and Biochemistry, The University of California, Los Angeles, California 90095-1569, USA.
Journal of the American Chemical Society
|July 17, 2003
まとめ
この研究では,極置換剤を用いた新しい分子コンパスを合成し,それらの動的固体状態特性を明らかにした. 構造的変更は,結晶の詰め込みと回転力学に影響を与え,分子運動の洞察を提供します.
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
- オーガニック・シンセシス オーガニック・シンセシス
背景:
- 分子ローターは,固体状態のダイナミックなプロセスを理解するために不可欠です.
- 以前の研究で,親分子コンパスの回転ダイナミクスを確立しました.
研究 の 目的:
- 異なる極置換物質を持つ6つの新しい結晶分子コンパスを合成し,特徴づけること.
- 結晶構造と分子動力学に対する極性群の影響を調査する.
- 固体状態における相転移と回転ポテンシャルを探求する.
主な方法:
- 分子コンパスの高度収束合成.
- 単結晶X線 difraktion,固体CPMAS (13)C NMR,微分スキャニング熱計 (DSC),および熱重計分析 (TGA) を用いた固体状態の特徴付け.
主要な成果:
- フローロ,シアノ,ニトロ,アミノ,ダイアミノ,およびニトロアミノの置換剤を含む6つの結晶分子コンパスが成功して合成されました.
- 同型構造と類似の性質は,小さな構造的乱れで観察されました.
- クラスレート構造と溶媒のない相が特定され,相移行は60°Cから130°Cの間に発生した.
- 分析により,フェニレン群の非対称,二重の回転ポテンシャルが示唆されている.
結論:
- 分子コンパスにおける極置換物質は,予測可能な構造的および動的行動につながります.
- フェーズトランジションにより,性質を保持した溶媒のない結晶性物質が形成されます.
- この研究は,制御された固体ダイナミクスを持つ分子材料の設計のための基礎を提供します.
関連する概念動画
Molecules with Multiple Chiral Centers
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...
Symmetry Elements in a Crystal
Crystal symmetry operations are isometric transformations that map objects onto indistinguishable copies while preserving distances, angles, and volumes. The simplest symmetry operation is translation, which shifts the entire infinite crystal lattice parallelly by a translation vector.Crystallographic rotations involve rotations by an angle of 2π/n around an axis without changing the positions of points on the axis. It is called the rotational axis of the symmetry, denoted by n. The combination...
The Seven Crystal Systems: Overview
Crystals with various point group symmetries belong to different crystal classes, which are synonymous terms. Despite being in the same class, crystals may have distinct shapes, like cubes and octahedra. There are 32 three-dimensional point groups, all of which are systematically divided into seven crystal systems.The basic cubic crystal system, exemplified by NaCl, features orthogonal vectors (α = β = �� = 90°) of equal lengths (a = b = c). When specific requirements are not imposed on the...
Crystallographic Point Groups
Crystallographic point groups represent the various symmetry operations that can occur within crystals. They are unique in that at least one point will always remain unchanged during these actions. For instance, consider the triclinic system. This system, devoid of any axis or plane of symmetry, aligns with the C1 and Ci point groups.where Cᵢ is characterized solely by a center of inversion.Contrastingly, the monoclinic system introduces an element of symmetry. This system with one plane and...
Determination 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...
Imperfections in Crystal Structure: Point, Line and Plane Defects
A perfect crystal, in theory, has a uniform structure with the same unit cell and lattice points throughout. However, any deviation from this periodic arrangement is known as an imperfection or defect. These defects can be categorized into three types: point, line, and plane defects.Point defects occur when there is a deviation from the ideal due to missing atoms, displaced atoms, or additional atoms. These imperfections might occur due to imperfect packing during crystallization or because of...

