在铁弹性包含化合物中的相位过渡过程中,意外的客体运动
Mark D Hollingsworth1, Matthew L Peterson, Kevin L Pate
1Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA.
Journal of the American Chemical Society
|March 7, 2002
概括
含有特定客分子的尿素含有化合物 (UIC) 具有铁弹性特性. 一种新型化合物Cl ((CH2) 6CN/尿素显示出铁弹性域重定向和独特的相位过渡,这是由于客分子的构造变化造成的.
科学领域:
- 材料科学 材料科学 材料科学
- 晶体学 晶体学是指结晶学.
- 超分子化学 超分子化学
背景情况:
- 尿素含量化合物 (UIC) 对于研究铁弹性域切换和分子识别有价值.
- 某些UIC中的P2(1)/n包装模式具有堆叠的尿素六合环,其扭曲受客分子构造的影响.
- 这些UIC具有潜在的铁弹性,但由于结构要求和重大扭曲,域重定向受到阻碍.
研究的目的:
- 通过形成固体溶液,设计具有最小扭曲的六角对称性的铁弹性UIC.
- 为了研究UICs与混合类客人的铁弹性行为和相位过渡.
- 了解在堆叠循环UIC中限制固溶液形成的因素.
主要方法:
- 合成和结晶分析含有各种客体的尿素纳入化合物,包括像Cl ((CH2) 6CN/尿素这样的混合替代物化合物.
- 在机械应力下对铁弹性域重定向的研究.
- 可变温度的X射线衍射研究,以表征相位过渡.
主要成果:
- 不可能在不同系列的堆叠循环UIC之间形成固体溶液 (例如,Cl(CH2) 6Cl和NC(CH2) 6CN).
- Cl(CH2) 6CN/尿素晶体呈现最小的扭曲 (0.5%) 和显示铁弹性域重定位在高力.
- 在 -66°C的Cl(CH2) 6CN/尿素中发生了非拓化学相过渡,涉及由轻微的结构变化驱动的显著客体转换.
结论:
- 形成坚实的解决方案的困难源于不同类型的客人优先占用场地,而不是应变导向.
- 在Cl(CH2) 6CN/尿素的相位过渡过程中,大量的客体位移解释了制造混合固体溶液的局限性.
- 设计新材料需要对客主互动的细微了解,而不仅仅是简单的异构.
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