液晶相移行は,ポリエレクトロライトアンフィフィール複合体のスピンクロスオーバーを誘導する
Yves Bodenthin1, Guntram Schwarz, Zbigniew Tomkowicz
1University Siegen, FB7 Solid State Physics, D-57068 Siegen, Germany.
Journal of the American Chemical Society
|February 12, 2009
まとめ
鉄とニッケル金属の超分子ポリマーは,液晶を形成する. 加熱したFe-PACは,色変化で不可逆的なスピン・クロスオーバー (SCO) を誘導し,Ni-PACはSCOを示さない. 溶解すると元の状態が回復する.
科学分野:
- 協調化化学について
- マテリアルサイエンス 材料科学
- 超分子化学 超分子化学
背景:
- 金属上分子調整ポリエレクトロライト (MEPE) は,金属イオンとリガンドの自己組成によって形成されます.
- ディヘキサデシルリン酸 (DHP) などのアンフィフィルを組み込むと,液体結晶の性質を持つポリエレクトロライトアンフィフィール複合体 (PAC) が形成されます.
研究 の 目的:
- Fe-PACとNi-PACシステムにおけるスピン・クロスオーバー (SCO) 行動を調査する.
- 構造変化,熱特性,磁気移行の関係を理解する.
- PACにおけるSCOの行動を,クリーンなMEPEと比較する.
主な方法:
- Fe (II) または Ni (II) イオンと6,6',6''-bis (II) -ピリジル) -2,2':4',4'':2'',2''-クォーターピリジン (btpy) の自己組み合わさってMEPEを形成する.
- ディヘキサデシルフォスファート (DHP) による配列組成でPACを形成する.
- 熱分析 (熱重力測定分析,微分スキャニングカロメトリー) と磁気測定.
主要な成果:
- Fe-PACは加熱すると,色変化に伴い,低スピン状態から高スピン状態への不可逆的,ほぼ完全な (95%) スピン・クロスオーバーを示します.
- Fe-PACのSCOは,アンフィフィリックマトリックスと関連する構造変化の融解と関連しています.
- Fe-PACは冷却時に再組み立てられず,溶解によって回収できます;Ni-PACは同様の構造変化を示しますが,SCOはありません.
結論:
- Fe-PACの液晶マトリクスは,完全かつ不可逆的なSCOを可能にするために不可欠です.
- 対照的に,Fe-MEPEの固体構造は構造変化を制限し,サンプル履歴と溶媒含有量に依存する不完全なSCOにつながります.
- この研究は,金属超分子材料のSCO特性を制御するアンフィフィリック行列の役割を強調しています.
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