末端ダイアセチレンの一つの単結晶から単結晶へのトーポケミカルポリメリゼーション:二つの驚くべき変換により,同じ結合ポリマーが得られます
Xi Ouyang1, Frank W Fowler, Joseph W Lauher
1Department of Chemistry, State University of New York, Stony Brook, New York 11794-3400, USA.
Journal of the American Chemical Society
|October 9, 2003
まとめ
ホスト・ゲスト・ケミストリーは,トリプルヘリックス・コクリスタルの生成を可能にし,結末型ダイアセチレンの構造的に特徴づけられた最初のポリメリゼーションにつながり,結晶密度の有意な増加をもたらした.
科学分野:
- 超分子化学とは
- クリスタル工学は,クリスタル工学です.
- ポリマー化学 ポリマー化学
背景:
- ホスト・ゲスト・ケミストリーは,分子組立の正確な制御を提供します.
- 末端ダイアセチレンは,ポリメリゼーションのための多用性のあるモノマーです.
- 構造的特徴づけは,反応機構を理解する上で鍵となる.
研究 の 目的:
- ディピリジルオクサラミド宿主とレソルシノール由来末端ダイアセチレンのコ結晶を準備し,構造的に特徴づけること.
- これらのコクリスタル内の並べられたダイアセチレン機能のポリメリゼーションを調査する.
- ポリメリゼーション中の構造変化を分析し,異なるポリメリゼーション経路を比較する.
主な方法:
- ホスト・ゲストの複合がコクリスタルを形成する.
- コークリスタルとポリマーの構造的決定のためのX線結晶学.
- ポリメリゼーションを誘導するための熱分析.
主要な成果:
- 配列のダイアセチレン単位でトリプルヘリックスコクリスタル構造が形成されました.
- 加熱するとポリメリゼーションが起こり,対応するポリマーが得られました.
- 結晶水素も適切なダイアセチレン配列を示し,50°Cでポリメリ化しました.
- C1炭素の前例のない2.4 Åの内向きの振動により,結晶密度が9%増加しました.
- これは,末端のダイアセチレンの構造的に特徴づけられた最初のポリメリゼーションを表しています.
結論:
- ホスト・ゲスト化学は,ポリメリゼーションのためのダイアセチレン配列を正確に制御するための経路を提供します.
- 重要なC1の移動と密度の増加を含む観察されたポリメリゼーション機構は,新しい洞察を提供します.
- これらの発見は,制御された固体ポリメリゼーションを通じて,特性に合わせた新しい材料を設計する道を開く.
関連する概念動画
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...
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
![[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12422.jpg&w=3840&q=75)
01:21[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.
01:21Polymer Classification: Crystallinity
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
![[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F13097.jpg&w=3840&q=75)
01:24[3,3] Sigmatropic Rearrangement of Allyl Vinyl Ethers: Claisen Rearrangement
The Claisen rearrangement is a [3,3] sigmatropic rearrangement of allyl vinyl ethers to unsaturated carbonyl compounds. The rearrangement is a concerted pericyclic reaction proceeding via a chair-like transition state.