Krysiak Yaşar, Plana-Ruiz Sergi, Fink Lothar, Alig Edith, Bahnmüller Ulrich, Kolb Ute, Schmidt Martin U
Institute of Inorganic Chemistry, Leibniz University Hannover, Callinstraße 9, 30167 Hannover, Germany.
Department of Materials and Geoscience, Technische Universität Darmstadt, Petersenstrasse 23, 64287 Darmstadt, Germany.
J Am Chem Soc. 2024 Apr 10;146(14):9880-9887. doi: 10.1021/jacs.3c14800. Epub 2024 Mar 27.
Small molecule structures and their applications rely on good knowledge of their atomic arrangements. However, the crystal structures of these compounds and materials, which are often composed of fine crystalline domains, cannot be determined with single-crystal X-ray diffraction. Three-dimensional electron diffraction (3D ED) is already becoming a reliable method for the structure analysis of submicrometer-sized organic materials. The reduction of electron beam damage is essential for successful structure determination and often prevents the analysis of organic materials at room temperature, not to mention high temperature studies. In this work, we apply advanced 3D ED methods at different temperatures enabling the accurate structure determination of two phases of Pigment Orange 34 (CHNOCl), a biphenyl pyrazolone pigment that has been industrially produced for more than 80 years and used for plastics application. The crystal structure of the high-temperature phase, which can be formed during plastic coloration, was determined at 220 °C. For the first time, we were able to observe a reversible phase transition in an industrial organic pigment in the solid state, even with atomic resolution, despite crystallites being submicrometer in size. By localizing hydrogen atoms, we were even able to detect the tautomeric state of the molecules at different temperatures. This demonstrates that precise, fast, and low-dose 3D ED measurements enable high-temperature studies the door for general studies of nanocrystalline materials at the atomic level.
小分子结构及其应用依赖于对其原子排列的深入了解。然而，这些通常由精细晶畴组成的化合物和材料的晶体结构，无法通过单晶X射线衍射来确定。三维电子衍射（3D ED）已成为亚微米级有机材料结构分析的可靠方法。减少电子束损伤对于成功确定结构至关重要，并且常常阻碍在室温下对有机材料的分析，更不用说高温研究了。在这项工作中，我们在不同温度下应用先进的3D ED方法，能够准确确定颜料橙34（CHNOCl）两种相的结构，颜料橙34是一种联苯吡唑啉酮颜料，已工业化生产80多年并用于塑料应用。高温相的晶体结构可在塑料着色过程中形成，在220°C下确定。我们首次能够在固态工业有机颜料中观察到可逆相变，即使微晶尺寸为亚微米级，甚至具有原子分辨率。通过定位氢原子，我们甚至能够检测不同温度下分子的互变异构状态。这表明精确、快速和低剂量的3D ED测量为在原子水平上对纳米晶体材料进行一般研究打开了高温研究的大门。
