X-ray diffraction analysis of nonequilibrium states in crystals: Observation of an unstable conformer in flash-cooled crystals
X-ray diffraction analysis of nonequilibrium states in crystals: Observation of an unstable conformer in flash-cooled crystals
复制标题
DOI：
10.1021/ja038203l
复制
发表时间：
2004-03-24
影响因子：
15
通讯作者：
Ogawa, K
中科院分区：
文献类型：
--
作者：
Harada, J;Ogawa, K
一些分子骨架类似于芪和偶氮苯的分子在晶体中表现出取向无序。如果紊乱是动态的，则构象相互转换通过踏板运动发生。在这项研究中，（E）-芪（1）和偶氮苯（2）的X射线衍射分析进行了在不同温度下。我们成功地观察到的热力学非平衡态，所产生的快速冻结的构象相互转换在低温下。在90 K的晶体中的两种构象的人口1随冷却速率。从室温到90 K的2的晶体的闪速冷却使得有可能观察到在相同温度下不存在于平衡状态中的次要不稳定构象。
Some molecules with a molecular skeleton similar to that of stilbenes and azobenzenes show orientational disorder in the crystals. If the disorder is dynamic, a conformational interconversion takes place through a pedal motion. In this study X-ray diffraction analyses of (E)-stilbene (1) and azobenzene (2) were carried out at various temperatures. We succeeded in observing thermodynamic nonequilibrium states that were generated by fast freezing of the conformational interconversion at low temperatures. The populations of the two conformers in crystals of 1 at 90 K varied with the cooling rate. Flash cooling of a crystal of 2 from room temperature to 90 K made it possible to observe the minor unstable conformer that does not exist in the equilibrium state at the same temperature.