TY - JOUR

T1 - High Temperature Electron Diffraction on Organic Crystals

T2 - In Situ Crystal Structure Determination of Pigment Orange 34

AU - Krysiak, Yaşar

AU - Plana-Ruiz, Sergi

AU - Fink, Lothar

AU - Alig, Edith

AU - Bahnmüller, Ulrich

AU - Kolb, Ute

AU - Schmidt, Martin U.

PY - 2024/4/10

Y1 - 2024/4/10

N2 - 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 (C34H28N8O2Cl2), 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 in situ studies of nanocrystalline materials at the atomic level.

AB - 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 (C34H28N8O2Cl2), 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 in situ studies of nanocrystalline materials at the atomic level.

UR - http://www.scopus.com/inward/record.url?scp=85189018655&partnerID=8YFLogxK

U2 - 10.1021/jacs.3c14800

DO - 10.1021/jacs.3c14800

M3 - Article

C2 - 38536667

AN - SCOPUS:85189018655

VL - 146

SP - 9880

EP - 9887

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

SN - 0002-7863

IS - 14

ER -