Abstract
3D electron diffraction (3D ED), also known as micro-crystal electron diffraction (MicroED), is a rapid, accurate, and robust method for structure determination of submicron-sized crystals. 3D ED has mainly been applied in material science until 2013, when MicroED was developed for studying macromolecular crystals. MicroED was considered as a cryo-electron microscopy method, as MicroED data collection is usually carried out in cryogenic conditions. As a result, some researchers may consider that 3D ED/MicroED data collection on crystals of small organic molecules can only be performed in cryogenic conditions. In this work, we determined the structure for sucrose and azobenzene tetracarboxylic acid (H4ABTC). The structure of H4ABTC is the first crystal structure ever reported for this molecule. We compared data quality and structure accuracy among datasets collected under cryogenic conditions and room temperature. With the improvement in data quality by data merging, it is possible to reveal hydrogen atom positions in small organic molecule structures under both temperature conditions. The experimental results showed that, if the sample is stable in the vacuum environment of a transmission electron microscope (TEM), the data quality of datasets collected under room temperature is at least as good as data collected under cryogenic conditions according to various indicators (resolution, I/σ(I), CC1/2 (%), R1, Rint, ADRA).
Highlights
Published: 9 November 2021Electrons are ideal radiation sources for diffraction and imaging experiments on submicron-sized crystals because of their strong interaction with matter
The H4 ABTC molecules were synthesized according to the literature [32] and H4 ABTC crystals were formed from the unreacted linker during synthesis of a Zr-based metal–organic framework (MOF) [33]
transmission electron microscope (TEM) grid without using any solvents. 3D electron diffraction (3D ED) data were collected on a JEOL JEM-2100 with a LaB6 filament at both room temperature and cryogenic temperature
Summary
Taimin Yang 1 , Steve Waitschat 2 , Andrew Kentaro Inge 1 , Norbert Stock 2 , Xiaodong Zou 1, * and Hongyi Xu 1, *. Molecules by 3D Electron Diffraction at Cryogenic and Room Temperature. Abstract: 3D electron diffraction (3D ED), known as micro-crystal electron diffraction (MicroED), is a rapid, accurate, and robust method for structure determination of submicron-sized crystals
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