...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Acta Crystallographica, Section B. Structural Science >Five more phases of the structural family [M(H2O)(2)(15-crown-5)](NO3)(2)
【24h】

Five more phases of the structural family [M(H2O)(2)(15-crown-5)](NO3)(2)

机译：结构族的另外五个阶段[M（H2O）（2）（15-crown-5）]（NO3）（2）

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

The structures of five more phases of the structural family of compounds [M(H2O)(2)(15-crown-5)](NO3)(2) have been determined. All of these phases are stable at room temperature or above, but transform to other phases if cooled slowly. All five phase transitions take place without significant damage to the single crystal. The M = Co phase, which has a three-dimensional hydrogen-bonding pattern, is a disordered version of the structure known at room temperature; Z' changes from 2 to 1/2. The other four structures have a two-dimensional hydrogen-bonding pattern, are all modulated variants of the same basic cell (or subcell) and are at least mostly ordered. For M = Mg and Zn the structure found somewhat above room temperature is the Z' = 8 variant found previously for M = Fe. For M = Cu and Ni the Z' = 2 phase found is the same as seen previously for one of the room-temperature polymorphs with M = Mn. There are now two phases and one transition known for each M studied that has a two-dimensional hydrogen-bonding pattern. The changes in the modulation patterns during these transitions are Z' 3 <-> 8 (Mg, Fe, Zn), Z' 3 <-> 2 (Mn, Ni) and Z' 5 <-> 2 (Cu). In all two-dimensional hydrogen-bonded crystals the alternation pattern of conformational enantiomers along the modulation direction becomes more perfect above the phase transition. All stable [M(H2O)(2)(15-crown-5)](NO3)(2) phases whose existence at accessible temperatures is indicated by differential scanning calorimetry (DSC) have now been characterized.
机译：确定了化合物[M（H2O）（2）（15-crown-5）]（NO3）（2）的结构族的另外五个相的结构。所有这些相在室温或更高温度下均稳定，但如果缓慢冷却，则会转变为其他相。所有五个相变都发生，而对单晶没有明显损坏。 M = Co相具有三维氢键模式，是室温下已知结构的无序形式。 Z'从2变为1/2。其他四个结构具有二维氢键模式，是同一基本单元（或子单元）的所有已调制变体，并且至少大部分是有序的。对于M = Mg和Zn，在高于室温的条件下发现的结构是先前对于M = Fe发现的Z'= 8变体。对于M = Cu和Ni，发现的Z'= 2相与先前对于其中M = Mn的一种室温多晶型物所见相同。现在，对于每个研究的M，都有两个相和一个跃迁，具有二维氢键模式。在这些转变期间，调制模式的变化是Z'3-8（Mg，Fe，Zn），Z'3-2（Mn，Ni）和Z'5-2（Cu）。在所有二维氢键结晶体中，构象对映异构体在调制方向上的交替模式在相变以上都变得更加完美。现在已经对所有稳定的[M（H2O）（2）（15-crown-5）]（NO3）（2）相进行了表征，这些相在差示扫描量热法（DSC）指示的可及温度下存在。

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