分子的に秩序づけられた,しかし非結晶のシリケートフレームワークの構造を決定するための一般的なプロトコル
Darren H Brouwer1, Sylvian Cadars, Juergen Eckert
1Department of Chemistry, Redeemer University College, Ancaster, Ontario, Canada, L9K 1J4.
Journal of the American Chemical Society
|April 9, 2013
まとめ
この研究は,非結晶固体の構造を決定するために,X線 difraktion (XRD) と固体核磁気共鳴 (NMR) を組み合わせた新しい方法を提示しています. このアプローチは,層状のシリケート材料のための3つの類似したフレームワーク構造を成功裏に特定しました.
科学分野:
- マテリアルサイエンス 材料科学
- 固体化学 固体化学
- クリスタログラフィーです.
背景:
- 短距離の秩序を持つ非結晶固体の構造を決定することは困難です.
- X線 difraktion (XRD) のような伝統的な方法は,長距離周期性がないことによって制限されています.
- 層状シリケートは,通常,従来の分析に抵抗する複雑な構造を示します.
研究 の 目的:
- 分子的に秩序づけられた非結晶固体の構造を解明するための一般的なプロトコルの開発と実証.
- このプロトコルを,三次元 (3D) の長距離処理が欠けている表面活性剤指向の層状シリケートに適用する.
- 実験データと互換性のある候補フレームワーク構造を特定し,精錬する.
主な方法:
- 単元細胞パラメータのためのX線 difraktion (XRD) の統合.
- 詳細なサイト分析と接続性のために,1次元と2次元固体核磁気共鳴 (NMR) スペクトロスコピーの利用.
- 第1原理の量子化学計算の適用,密度関数理論 (DFT) を含め,構造の精細化と検証.
主要な成果:
- この研究では,長距離3D周期性のない層状シリケートの構造的制約を成功裏に決定しました.
- XRDと固体 (29) Si NMRデータを組み合わせて,DFT計算とともに,小さな候補構造を特定しました.
- 3つの密接に関連し,トポロジ的に同等のフレームワーク構成は,すべての実験データと理論データと一致することが判明しました.
結論:
- 開発されたプロトコルは,複雑な非結晶固体の特徴づけに有効です.
- 特定された構造は,層層のシリケートフレームワークの複雑な性質を強調しています.
- 発見は,材料に共存する,または微妙に分布した構造的順序が含まれている可能性が高いことを示唆しています.
関連する概念動画
Structures 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...
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...
Ionic Crystal Structures
Ionic crystals consist of two or more different kinds of ions that usually have different sizes. The packing of these ions into a crystal structure is more complex than the packing of metal atoms that are the same size.
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
Crystal Field Theory - Octahedral Complexes
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
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...
Metallic Solids
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability. Many...


