Chen Pohua, Liu Yang, Zhang Chaochao, Huang Fei, Liu Leifeng, Sun Junliang
College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing, China.
ReadCrystal Technology Co., Jiangsu, China.
Front Mol Biosci. 2022 Feb 7;8:821927. doi: 10.3389/fmolb.2021.821927. eCollection 2021.
The crystalline sponge method has shown to be a novel strategy for the structure determination of noncrystalline, oily, or trace amount of a compound. A target compound was absorbed and oriented orderly in the pregrown porous crystal for x-ray diffraction analysis. However, the diffusion in the micron-sized crystals is rather difficult. Lots of trial-and-error experiments are needed to optimize the guest-soaking process and to improve data quality. Nanocrystals are better in diffusion, yet it could not conduct a single crystal x-ray diffraction (SCXRD) analysis. Three-dimensional electron diffraction (3D-ED) is a powerful diffraction tool for the structure determination of small crystals. In this work, we successfully carried out the crystalline sponge method by 3D-ED technique using {(ZnI)-[2,4,6-tris(4-pyridyl)-1,3,5-triazine]·x(guest)} (1-Guest) porous complex nanocrystals. On account of the better diffuse ability of nanocrystals, the time needed for solvent exchange and guest soaking protocols are shortened 50-fold faster versus the original protocol. The crystal structure of the crystalline sponge incorporated with three different guests was fully resolved using a merged dataset. The structure model was identical to previously reported ones using x-ray, showing that the accuracy of the 3D-ED was comparable with SCXRD. The refinement results can also give the precise occupancy of the guest molecule soaked in the porous crystal. This work not only provides a new data collection strategy for crystalline sponge method but also demonstrates the potential of 3D-ED techniques to study host-guest interaction by solving the fine structure of porous material.
晶体海绵法已被证明是一种用于确定非晶态、油性或痕量化合物结构的新策略。目标化合物被吸收并有序排列在预生长的多孔晶体中，用于X射线衍射分析。然而，在微米级晶体中的扩散相当困难。需要进行大量反复试验的实验来优化客体浸泡过程并提高数据质量。纳米晶体在扩散方面表现更好，但无法进行单晶X射线衍射（SCXRD）分析。三维电子衍射（3D-ED）是一种用于确定小晶体结构的强大衍射工具。在这项工作中，我们使用{(ZnI)-[2,4,6-三(4-吡啶基)-1,3,5-三嗪]·x(客体)}（1-客体）多孔复合纳米晶体，通过3D-ED技术成功实施了晶体海绵法。由于纳米晶体具有更好的扩散能力，与原始方案相比，溶剂交换和客体浸泡方案所需的时间缩短了50倍。使用合并数据集完全解析了包含三种不同客体的晶体海绵的晶体结构。该结构模型与先前报道的使用X射线的模型相同，表明3D-ED的准确性与SCXRD相当。精修结果还可以给出浸泡在多孔晶体中的客体分子的精确占有率。这项工作不仅为晶体海绵法提供了一种新的数据收集策略，还通过解析多孔材料的精细结构证明了3D-ED技术在研究主客体相互作用方面的潜力。
