圧力-温度空間における金属-有機枠組の多形性
Remo N Widmer1, Giulio I Lampronti1, Siwar Chibani2
1Department of Earth Sciences , University of Cambridge , Downing Street , Cambridge CB2 3EQ , U.K.
Journal of the American Chemical Society
|May 24, 2019
まとめ
高圧と高温で ZIF-4 の4つの新段階が明らかになりました これらの発見は,極端な条件下でZIF材料の複雑な段階の振る舞いを強調しています.
科学分野:
- 材料科学
- クリスタルグラフィー
- 化学について
背景:
- メタル・オーガニック・フレームワーク (MOF) は様々な構造と特性を有しています.
- 極端な条件下でのMOFの相安定性を理解することは,それらのアプリケーションにとって極めて重要です.
- ZIF-4 (Zn ((イミダゾラート) 2) は,様々な用途の可能性があるよく研究されたMOFです.
研究 の 目的:
- 同時に高圧と高温下でのZIF-4の相安定性と多形性を調査する.
- ZIF-4の圧力-温度相図を構成する.
- ZIF-4の新しい高圧高温相の結晶構造を解明する.
主な方法:
- ZIF-4の研究には,インサイト粉末X線 difraktion (PXRD) が使用された.
- 実験は同時に高圧 (最大8GPa) と高温 (最大600°C) で実施された.
- 密度関数理論 (DFT) の計算を使用して,新しい相の総エネルギーを評価した.
主要な成果:
- ZIF-4の複雑な圧力-温度相図が作成され,4つの新しい高圧-高温相が明らかになった.
- 2つの新しいフェーズ,ZIF-4-cp-IIとZIF-hPT-IIの結晶構造は,PXRDデータを用いて解きました.
- Cd (イミダゾラート) 2とHg (イミダゾラート) 2との同構造であるZIF-hPT-IIは,極端な条件下での驚くべき安定性を示した.
結論:
- この研究では,ZIF-62のような関連ZIFと比較して,ZIF-4の相性が著しく複雑であることが明らかになりました.
- この発見は,MOFの複雑なエネルギー景観を探索する際の高圧と高温の組み合わせの有用性を示しています.
- 発見されたフェーズとその性質は,MOFの構造的多様性と安定性に関する新しい洞察を提供します.
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