铁(III) 旋转交叉化合物在室温周围具有广泛的表面热歇斯底里
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
概括
旋转交叉化合物[Feqsal]2]NCSe-MeOH和[Feqsal]2]NCSe-CH2Cl2最初表现出明显的广泛的热歇斯底里循环. 在溶剂损失后,它们在升温时表现出明显的两步旋转交叉行为,在降温时表现出一步旋转交叉行为.
科学领域:
- 材料科学 材料科学 材料科学
- 固态化学 固态化学
- 磁力学 磁力学 是一种
背景情况:
- 旋转交叉 (SCO) 化合物是可以在低旋转和高旋转状态之间切换的分子材料.
- 对于传感器,内存设备和显示器的潜在应用,SCO复合体很有趣.
- 了解影响SCO行为的因素,如歇斯底里和合作性,对于材料设计至关重要.
研究的目的:
- 为了研究两个新型铁 (II) 化合物的磁性特性和旋转交叉行为:[Fe(qsal) 2NCSe-MeOH (1) 和[Fe(qsal) 2NCSe-CH2Cl2 (2).
- 描述这些复合体中的热歇斯底里和自旋交叉过渡的性质.
- 探索分子间相互作用在观察到的SCO现象中的作用.
主要方法:
- 测量磁性属性 (温度依赖的易感性).
- 热重力测量分析 (TGA) 用于确定溶剂损失温度.
- 对旋转交叉过渡温度和歇斯底里宽度的分析.
- 使用先前建立的理论框架对SCO行为进行建模.
主要成果:
- 化合物1和2最初由于溶剂损失而表现出广泛的明显热歇斯底里循环 (分别为140K和180K).
- 在去除溶剂后,两种化合物在升温时 (以215 K和282 K为中心) 呈现两步旋转交叉,在冷却时 (以212 K为中心) 呈现一步交叉.
- 在变暖过渡的第二阶段观察到70K的显著hysteresis宽度,这是SCO复合体中报告的最宽的范围之一,归因于分子间pi相互作用.
结论:
- 最初的宽歇斯底里循环是溶剂分子逃逸的工件.
- 这些化合物表现出复杂的旋转交叉行为,具有明显的多步过渡.
- oline和phenyl环之间的分子间pi相互作用是SCO过程中观察到的合作性和广泛的歇斯底里的关键.
- 通过使用理论模型,可以成功模拟实验性SCO行为.
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