同結晶化とは何ですか? 同結晶化とは pH指標メチル赤の状態は,フタル酸の結晶に表されている
Jason B Benedict1, Dawn E Cohen, Scott Lovell
1Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|April 20, 2006
まとめ
同結晶化は,メチル赤 (MR) を含めたフタル酸 (PA) で研究されました. PA結晶内の異なるMR種は,陽子結合によって異なっており,黄色と赤の色を生じ,以前のモデルに挑戦しています.
科学分野:
- クリスタルグラフィーです.
- 固体化学 固体化学
- スペクトル顕微鏡検査です.
背景:
- 同結晶化は,2つ以上の化合物が一緒に結晶化するプロセスです.
- ホスト結晶内のゲスト分子の振る舞いを理解することは,材料科学にとって極めて重要です.
- フェタル酸 (PA) とメチル赤 (MR) は,シン結晶化メカニズムを調査するために選ばれました.
研究 の 目的:
- フタル酸 (PA) とメチル赤 (MR) を用いたシン結晶化の概念を再調査する.
- PA-MR混合結晶における観測された色付けの背後にあるメカニズムを解明する.
- PAマトリックス内に存在するメチルレッド (MR) の異なる種を分析する.
主な方法:
- X線結晶学を用いて,MRとその共結晶の構造を決定した.
- 線形二重断層と線形二重断層の測定は,混合結晶で行われた.
- フォースフィールドと分子軌道計算を用いて,PA内のMR相互作用を研究した.
主要な成果:
- 2つの異なるMR種がPAで特定され,エネルギー,極化,顔の選択性において異なっている.
- 色の違い (黄色と赤) は,MRのカルボキシル酸群の陽子化状態 (分子内対分子間水素結合) に起因する.
- 混合結晶を加熱すると,MRの方向転換,相分離,そしてMR豊富な領域への再結晶が誘発される.
結論:
- この研究は,PA結晶におけるMRの振る舞いの微妙な理解を提供し,水素結合の重要性を強調しています.
- コクリステル構造は,稀な固体溶液を正確に表現できない可能性があり,モデリングに注意が必要です.
- PAとMRの同時結晶は観察されなかったが,加熱時にMRの方向転換と相分離は,同結晶のより広範な定義と一致する.
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...
02:42Ionic 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...
03:05Acid Strength and Molecular Structure
Binary Acids and Bases
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...
01:19Crystal Density
The crystal lattice structure of a material allows us to determine how many molecules exist in its unit cell. With this information, alongside the unit-cell parameters - three distance parameters (a, b, c) and three angular parameters (α, β, γ).Density (ρ) = (Z × M) / (a × b × c × NA)where:Z is the number of formula units per unit cellM is the molar mass of the substancea, b, and c are the edge lengths of the unit cellNA is Avogadro’s numberFor a simple cubic lattice, atoms are located only at...
01:25Imperfections 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...
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...