...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Crystal growth & design >Polymorphic Phase Transition in 4 '-Hydroxyacetophenone: Equilibrium Temperature, Kinetic Barrier, and the Relative Stability of Z '=1 and Z '=2 Forms
【24h】

Polymorphic Phase Transition in 4 '-Hydroxyacetophenone: Equilibrium Temperature, Kinetic Barrier, and the Relative Stability of Z '=1 and Z '=2 Forms

机译：4'-羟基乙酮中的多态性相转变：平衡温度，动力学屏障和Z'= 1和Z'的相对稳定性

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Particularly relevant in the context of polymorphism is understanding how structural, thermodynamic, and kinetic factors dictate the stability domains of polymorphs, their tendency to interconvert through phase transitions, or their possibility to exist in metastable states. These three aspects were investigated here for two 4'-hydroxyacetophenone (HAP) polymorphs, differing in crystal system, space group, and number and conformation of molecules in the asymmetric unit. The results led to a Delta(f)G(m)degrees-T phase diagram highlighting the enantiotropic nature of the system and the fact that the Z' = 1 polymorph is not necessarily more stable than its Z' = 2 counterpart. It was also shown that the form II -> form I transition is entropy driven and is likely to occur through a nucleation and growth mechanism, which does not involve intermediate phases, and is characterized by a high activation energy. Finally, although it has been noted that conflicts between hydrogen bond formation and close packing are usually behind exceptions from the hypothesis of Z' = 1 forms being more stable than their higher Z' analogues, in this case, the HAP polymorph with stronger hydrogen bonds (Z' = 2) is also the one with higher density.
机译：在多态性的背景下特别相关是理解结构，热力学和动力学和动力学因素如何决定多晶型物的稳定性畴，它们倾向于通过相转变的倾向，或它们在亚稳态中存在的可能性。这里研究了这三个方面的两种4'-羟基乙酮（HAP）多晶型物，在晶体系统，空间组和不对称单元中分子的数量和兼容性不同。结果导致了Δ（f）g（m）的度数-t相图，突出了系统的对抗性性质以及z'= 1多晶型物不一定比其z'= 2对应物更稳定的事实。还表明，II - >形式的I型过渡是熵驱动的，并且可能通过成核和生长机制发生，其不涉及中间阶段，并且其特征在于高活化能量。最后，尽管已经注意到氢键形成和关闭包装之间的冲突通常是从Z'= 1的假设的例外后面比其更稳定的形式，但在这种情况下，具有较强的氢键的Hap多晶型物（Z'= 2）也是具有较高密度较高的人。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号