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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Ab initio structure determination of interlayer expanded zeolites by single crystal rotation electron diffraction
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Ab initio structure determination of interlayer expanded zeolites by single crystal rotation electron diffraction

机译：单晶旋转电子衍射从头算结构测定层间膨胀沸石

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摘要

Layered solids often form thin plate-like crystals that are too small to be studied by single-crystal X-ray diffraction. Although powder X-ray diffraction (PXRD) is the conventional method for studying such solids, it has limitations because of peak broadening and peak overlapping. We have recently developed a software- based rotation electron diffraction (RED) method for automated collection and processing of 3D electron diffraction data. Here we demonstrate the ab initio structure determination of two interlayer expanded zeolites, the microporous silicates COE-3 and COE-4 (COE-n stands for International Network of Centers of Excellence-n), from submicron-sized crystals by the RED method. COE-3 and COE-4 are built of ferrierite-type layers pillared by (–O–Si(CH_3)_2–O–) and (–O–Si(OH)_2–O–) linker groups, respectively. The structures contain 2D intersecting 10-ring channels running parallel to the ferrierite layers. Because both COE-3 and COE-4 are electron-beam sensitive, a combination of RED datasets from 2 to 3 different crystals was needed for the structure solution and subsequent structure refinement. The structures were further refined by Rietveld refinement against the PXRD data. The structure models obtained from RED and PXRD were compared.
机译：层状固体通常形成薄的板状晶体，该晶体太小而无法通过单晶X射线衍射研究。尽管粉末X射线衍射（PXRD）是研究此类固体的常规方法，但由于峰的加宽和峰的重叠而存在局限性。我们最近开发了一种基于软件的旋转电子衍射（RED）方法，用于自动收集和处理3D电子衍射数据。在这里，我们演示了通过RED方法从亚微米级晶体中检测两种中间层膨胀沸石（微孔硅酸盐COE-3和COE-4（COE-n代表国际卓越中心-n的国际网络））的从头算结构。 COE-3和COE-4是分别由（–O–Si（CH_3）_2–O–）和（–O–Si（OH）_2–O–）连接基团组成的镁碱岩型层构成的。该结构包含平行于镁碱沸石层的2D相交10环通道。由于COE-3和COE-4都对电子束敏感，因此需要2到3个不同晶体的RED数据集的组合来进行结构求解和后续的结构优化。通过Rietveld细化对PXRD数据进一步细化了结构。比较了从RED和PXRD获得的结构模型。

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