安定した螺旋型ポリグアニジン:ポリ[N-(1-アンチル) -N'-[(R) -および/または (S) -3,7-ジメチロクチル]グアニジン]
Hong-Zhi Tang1, Yujie Lu, Gonglu Tian
1Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA.
Journal of the American Chemical Society
|March 25, 2004
まとめ
チラルの触媒は,アチラルのモノマーからポリグアニジンを生成する. 一部のポリマーは高温でラセミゼーションし,他のものは安定したヘリクスを形成し,ポリマーの構造と安定性を制御します.
科学分野:
- ポリマー化学のポリマー化学について
- アシンメトリック・カタリシス
- ステレオ化学 ステレオ化学
背景:
- チラル触媒は,ステレオレギュラーポリマーの合成に不可欠です.
- カーボダイミドポリメリゼーションは,潜在的な応用を持つポリグアニジンへの経路を提供します.
- ポリマーの戦術性や形状を制御することは,材料の特性を調整する鍵です.
研究 の 目的:
- チラルBINOL-Ti触媒を用いたアキラルカルボディミド単体による非対称的ポリメリゼーションを調査する.
- ポリマー領域の規則性および立体化学に対する触媒構造の影響を調査する.
- 合成されたポリグアニジンの熱安定性および形状的振る舞いを研究する.
主な方法:
- (R) -および/または (S) -BINOL-Tiキラル触媒を用いた非対称ポリメリゼーション.
- N-(1-アントリル) -N'-アルキルカルボジミドの合成.
- ラセミゼーションの運動を研究する annealing 実験.
- スペクトル解析 (NMR,UV-Vis) と溶液中の構成研究.
主要な成果:
- BINOL-Ti触媒を用いて溶解性非地域正規ポリグアニジン (Poly-R1,Poly-S1) を採取した.
- Poly-R1は,冷却 (70~80°C) 時に ~36 kcal/molの活性化エネルギーでゆっくりとレース化しました.
- 高度地域規則性のポリグアニジン (ポリ-R2,ポリ-S2) は,チタン (IV) トリフッロエト酸化物を用いて合成されました.
- Poly-R2とPoly-S2は,動力または熱力学的制御から独立して,溶液中の安定した螺旋形状を採用しました.
結論:
- キラル触媒の選択は,ポリグアニジンの地域規則性およびステレオ化学的安定性に大きく影響する.
- 非地域正規のポリグアニジンにおけるラセミゼーションは,熱的に活性化されたプロセスである.
- 高度地域規則性のポリグアニジンは,安定した螺旋構造を示しており,オーダーされた材料の可能性を示唆しています.
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