リバーシブルな結晶-結晶移行のヘクサモルフ結晶系におけるH結合と結晶パッキングの挫折
Emmanuele Parisi1, Emanuela Santagata2, Elena Simone1
1Department of Applied Science and Technology, Politecnico of Turin, Corso Duca degli Abruzzi 24, I-10129 Turin, Italy.
Journal of the American Chemical Society
|July 5, 2024
まとめ
この研究は,単結晶から単結晶への可逆変換を含む多様な多形変異を示す新しい化合物,ImBを明らかにしています. これらの結晶相の振る舞いを理解することで このような移行を予測する 洞察が得られます
科学分野:
- 固体化学
- クリスタルグラフィー
- 材料科学
背景:
- ポリモルフィズム,すなわち固体の物質が複数の結晶形に存在する能力はよく研究されています.
- しかし,これらの多形相の間の移行は,まだ研究されていない.
- 分子の合理的な設計は 複雑なポリモルフィックな行動につながります
研究 の 目的:
- 挫折した水素結合を示す合理的に設計された化合物 (ImB) の相行動を調査する.
- モノトロピック/エナチオトロピック,高速/遅い,拡散/移位,および単結晶から単結晶 (SCSC) を含む多様なタイプのポリモルフィックトランジションを紹介する.
- 異なった非対称単位含有量 (Z') のポリモルフの関係を探求する.
主な方法:
- 挫折したH結合を持つ新しい化合物 (ImB) の設計と合成
- 実験的な研究によって6つの異なる結晶相 (I-VI) を特定した.
- 5つの結晶-結晶移行の特徴,その可逆性,メカニズム (SCSC,拡散性,移位性),運動性 (高速/遅い),および熱力学 (モノトロピー/エナチオトロピー,低冷却) を分析する.
主要な成果:
- 複合体ImBは多形変異の幅広い範囲を表示し,モデルシステムとして機能します.
- ステージIV,III,IIの間に逆転可能なSCSC移行が観察された6つのポリモルフが特定されました.
- 高温フェーズII (Z'=1) と低温フェーズIV (Z'=2) の間にある,室温では安定している.
- すべてのポリモルフは同じ O-H··OC 水素結合シンソンを共有し,無限鎖またはリングテトラマーを形成する.
- リバーシブルなSCSCトランジションのシーケンス (IV III II) は,H結合鎖構造のダイナミックな対称性の変化を示している.
結論:
- 化合物ImBは,様々な多形変異型を研究するための包括的なプラットフォームを提供します.
- 観察された可逆性SCSC移行は,対称性と超分子組成の複雑な相互作用を強調しています.
- この発見は,結晶材料における単結晶から単結晶への移行を予測するためのロードマップに寄与する.
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