鉄 (((III) スピン・クロスオーバー化合物で,室温の周りに広い表面的な熱ヒステレスがある
1Special Research Laboratory for Optical Science, Kanagawa Academy of Science and Technology, East 412, 3-2-1 Sakado, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012, Japan.
Journal of the American Chemical Society
|November 22, 2001
まとめ
スピン・クロスオーバー化合物[Fe(qsal) ]2NCSe-MeOHと[Fe(qsal) ]2NCSe-CH2Cl2は当初,明らかに広い熱ヒステレスループを示している. 溶媒の損失の後,それらは,加熱時に2段階,冷却時に1段階のスピン・クロスオーバー行動を示します.
科学分野:
- マテリアルサイエンス 材料科学
- 固体化学 固体化学
- マグネチズム (磁気) とは
背景:
- スピン・クロスオーバー (SCO) 化合物は,低スピン状態と高スピン状態を切り替えることができる分子材料です.
- SCOコンプレックスは,センサー,メモリデバイス,ディスプレイにおける潜在的なアプリケーションに興味があります.
- ヒステレスと協同性などのSCO行動に影響を与える要因を理解することは,材料設計において極めて重要です.
研究 の 目的:
- 2つの新しい鉄 (II) 化合物の磁気特性とスピンクロスオーバーの行動を調査する: [Fe (((qsal) 2NCSe-MeOH (1) と [Fe (((qsal) 2NCSe-CH2Cl2 (2).
- これらの複合体における熱ヒステレスとスピン・クロスオーバー・トランジションの性質を特徴付ける.
- 観測されたSCO現象における分子間相互作用の役割を調査する.
主な方法:
- 磁気特性測定 (温度に依存する感受性).
- 溶媒損失温度を決定するための熱重力測定分析 (TGA).
- スピン・クロスオーバーの移行温度とヒステレス幅の分析.
- 以前に確立された理論的枠組みを使用して,SCO行動のモデリング.
主要な成果:
- 化合物1と2は,溶媒の損失により,最初は広大な熱ヒステレスループ (それぞれ140Kと180K) を示した.
- 溶媒の除去後,両化合物は加熱時に2段階のスピン・クロスオーバー (中心は215Kと282K) と冷却時に1段階のクロスオーバー (中心は212K) を示した.
- 温暖化移行の第2段階には70 Kの有意なヒステレス幅が観測され,これはSCO複合体で報告されている中で最も幅の広いものの1つで,分子間PI相互作用に起因する.
結論:
- 初期の広いヒステレスループは,溶媒分子脱出の人工物である.
- 化合物は複雑なスピン・クロスオーバーの振る舞いを示し,明確な複数段階の移行を示している.
- キノリンとフェニル環の間の分子間PI相互作用は,SCOプロセスにおける観察された協力性と広範なヒステリシスの鍵です.
- 実験的なSCOの振る舞いは,理論的なモデルを使ってうまくシミュレートできます.
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