自分で組み立てたナノチューブが,酸エステンのゲストを逆向きに結合します
Linda S Shimizu1, Andrew D Hughes, Mark D Smith
1Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, USA. shimizul@mail.chem.sc.edu
Journal of the American Chemical Society
|December 5, 2003
まとめ
研究者は,bis-ureaのマクロサイクルから新しい有機ナノチューブを作成しました. この再利用可能な材料は,高熱安定性を発揮し,ゲスト分子のための有機ゼオライトとして機能します.
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
- ナノテクノロジー ナノテクノロジー
背景:
- マクロサイクル化合物は,自己組み立てのためのユニークな構造的モチーフを提供します.
- 水素結合は,超分子構造の形成における重要な相互作用である.
- 有機ナノチューブは,ホスト-ゲスト化学と分離アプリケーションの機会を提供します.
研究 の 目的:
- 大量のビス尿素マクロサイクルを合成する.
- マクロサイクルのセルフアセンブリをコラムナノチューブに調査する.
- 結果となる有機ナノチューブの熱安定性と潜在的な応用を評価する.
主な方法:
- 大量のビス尿素マクロサイクルの合成.
- ナノチューブを形成するための自己組み立ての研究.
- 熱安定性試験 (熱重力測定分析) 熱安定性試験 (熱重力測定分析) 熱安定性試験 (熱重力測定分析) 熱安定性試験 (熱重力測定分析) 熱安定性試験 (熱重力測定分析)
- エセティック酸によるゲストインクルージョン実験.
主要な成果:
- ビス尿素マクロサイクルの成功した合成.
- 安定した柱状の有機ナノチューブが形成され,内腔が大きくなる.
- ナノチューブの高熱安定性が180°Cまで実証されています.
- ナノチューブがエステル酸のようなゲスト分子をカプセル化する能力を確認しました.
結論:
- ビス尿素マクロサイクルは,頑丈な有機ナノチューブに自己組織化します.
- これらのナノチューブは,驚くべき熱安定性を有しており,要求の高いアプリケーションに適しています.
- 有機ナノチューブは,再利用可能な有機ゼオライトとして効果的に機能します.
関連する概念動画
01:24Acetals and Thioacetals as Protecting Groups for Aldehydes and Ketones
Acetals are formed by reacting two equivalents of alcohol with carbonyl compounds like aldehydes or ketones. Acetals are unaffected by bases, nucleophiles, oxidizing agents, and reducing agents. They serve as protecting groups for aldehydes and ketones. Acetals can be easily formed and also easily removed via mild acid hydrolysis.
In the presence of multiple functional groups, when selective reduction of one group over the other is desired, groups like aldehydes and ketones that form acetals...
In the presence of multiple functional groups, when selective reduction of one group over the other is desired, groups like aldehydes and ketones that form acetals...
01:01Acid Halides to Carboxylic Acids: Hydrolysis
Hydrolysis of acid halides is a nucleophilic acyl substitution reaction in which acid halides react with water to give carboxylic acids. The reaction occurs readily and does not require acid or a base catalyst.
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
01:13Esters to Carboxylic Acids: Acid-Catalyzed Hydrolysis
Hydrolysis of esters under acidic conditions proceeds through a nucleophilic acyl substitution. In the presence of excess water, the reaction proceeds in a reversible manner, forming carboxylic acids and alcohols.
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
During hydrolysis, the ester is first activated towards nucleophilic attack through the protonation of the carboxyl oxygen atom by the acid catalyst. The protonation makes the ester carbonyl carbon more electrophilic. In the next step, water acts as a nucleophile and adds to the...
01:28Amides to Carboxylic Acids: Hydrolysis
Amides can undergo either acid-catalyzed hydrolysis or base-promoted hydrolysis through a typical nucleophilic acyl substitution. Each hydrolysis requires severe conditions.
Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...
Acid-catalyzed hydrolysis:
Hydrolysis of amides under acidic conditions yields carboxylic acids. Since the reaction occurs slowly, hydrolysis requires the conditions of heat.
The mechanism begins with the protonation of the carbonyl oxygen by the acid catalyst. The protonation makes the amide carbonyl carbon more...
01:08Nitriles to Carboxylic Acids: Hydrolysis
Nitriles undergo acid-catalyzed hydrolysis or base-catalyzed hydrolysis to form a carboxylic acid. These reactions proceed via an amide intermediate.
01:19Preparation of Carboxylic Acids: Hydrolysis of Nitriles
Nitriles (R–CN) can be converted into carboxylic acids (R–COOH) upon treatment with aqueous acids, i.e., upon hydrolysis of nitriles. Under base-catalyzed conditions, carboxylate anions (R–COO−) are formed.