Metal-organic frameworks (MOFs) are porous coordination polymers which composed of inorganic metal centers (metal ions or metal clusters) and organic ligands. They have a porous internal structure with adjustable pore size, good thermal stability and excellent catalytic activity.
MOFs can usually only be synthesized as microcrystals and nanocrystals. X-ray diffraction method remains as the most widely used technique for the determination of crystal structures. However, it is necessary to obtain sufficient large and well-ordered crystals to harvest sufficient diffraction data. The process of culturing the crystals is time-consuming and laborious, which will affect the progress of project. Powder X-ray diffraction can also be used to determine the structure, but it is more difficult to perform.
Technical Features – MicroED
MicroED is a structure analysis technique which is developed based on cryo-transmission electron microscopy. The electron diffraction data is collected and analyzed by diffracting electrons from tiny crystals. Extremely small crystal sizes, like micro- and nano-sized crystals, can produce diffraction signals with sufficiently high signal-to-noise ratios. High resolution diffraction data can be provided quickly and efficiently, and it significantly reduces the requirements for sample shape, purity and size.
In 2020, Mircea Dincă's group at MIT and Junliang Sun's group at Peking University collaborated to collect electron diffraction data using cRED (equivalent to MicroED) technique on Cu3HHTT2, a two-dimensional conductive MOF of size 5-10 μm. The structure of this MOF was resolved by the data with a resolution of 1.5 Å. It was found to be a rare perfect AA stacking with shorter distance between adjacent layers than any other 2D MOF, and the correctness of this structure was verified by N2 adsorption experiments and high-resolution electron microscope photographs.
Our technical support and commercial colleagues will keep a smooth communication with you throughout the process. After establishing contact with you, we will understand your sample information and requirements in detail, and provide you with the best customized solution.
You need to fill out the Sample Information Form and provide the information required by the technical team for evaluation. For example, providing powder diffraction data and SEM data, the technical team will then provide you with the sample evaluation results and preliminary feasibility program.
3. Sample Delivery
You can choose the appropriate shipping method according to the characteristics of samples.
4.Data Collection and Processing
We will prepare and process the samples according to the characteristics of the samples and the purpose of the experiment. The sample is placed under the electron microscope to find the appropriate sample particles, and series of clear and high quality electron diffraction point images will be collected.
5. Structure Analysis
We will use different algorithms, such as Patterson method, direct method, charge flip method, maximum entropy method, genetic algorithm, simulated annealing method, etc., to resolve the distribution of atoms in the crystal and obtain the initial structure of the crystal. We will further refine the initial structure of the crystal to obtain a chemically reasonable and experimentally observed structure, and finally deliver the results.