New zeolite-like RUB-5 and its related hydrous layer silicate RUB-6 structurally characterized by electron microscopy

Abstract

This study made use of a recently developed combination of advanced methods to reveal the atomic structure of a disordered nanocrystalline zeolite using exit wave reconstruction, automated diffraction tomography, disorder modelling and diffraction pattern simulation. By applying these methods, it was possible to determine the so far unknown structures of the hydrous layer silicate RUB-6 and the related zeolite-like material RUB-5. The structures of RUB-5 and RUB-6 contain the same dense layer-like building units (LLBUs). In the case of RUB-5, these building units are interconnected via additional SiO4/2 tetrahedra, giving rise to a framework structure with a 2D pore system consisting of intersecting 8-ring channels. In contrast, RUB-6 contains these LLBUs as separate silicate layers terminated by silanol/siloxy groups. Both RUB-6 and RUB-5 show stacking disorder with intergrowths of different polymorphs. The unique structure of RUB-6, together with the possibility for an interlayer expansion reaction to form RUB-5, make it a promising candidate for interlayer expansion with various metal sources to include catalytically active reaction centres.

The Elusive Structure of Magadiite, Solved by 3D Electron Diffraction and Model Building

“…Static structural disorder which leads to various kinds of diffuse scattering remains a problem for structure analysis. However, even this has been successfully addressed several times with 3D ED data. − Several water-containing layered minerals have been successfully analyzed by 3D ED, despite all problems with crystal stability and specific crystal morphologies. − …”

3D Electron Diffraction Structure Determination of Terrylene, a Promising Candidate for Intermolecular Singlet Fission

“…Conversely, a 3D electron diffraction (3D ED) approach is conceptually comparable to single‐crystal XRD, but tolerates collecting data from much smaller volumes, in a range of about 10 0 –10 −4 μm 3 [9] . In recent years, 3D ED has been extensively used for the structure determination of various nanocrystalline materials, ranging from inorganics to macromolecules [10–18] . In the world of small‐molecule organic compounds, 3D ED has been successfully employed for unveiling the structure of organic frameworks, [19] semiconductors [20] peptides, [21,22] pharmaceuticals [23–26] and natural products, [27–29] all of which could not be addressed by XRD methods.…”

“… [9] In recent years, 3D ED has been extensively used for the structure determination of various nanocrystalline materials, ranging from inorganics to macromolecules. [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ] In the world of small‐molecule organic compounds, 3D ED has been successfully employed for unveiling the structure of organic frameworks, [19] semiconductors [20] peptides,[ 21 , 22 ] pharmaceuticals[ 23 , 24 , 25 , 26 ] and natural products,[ 27 , 28 , 29 ] all of which could not be addressed by XRD methods.…”

Design of Active Defects in Semiconductors: 3D Electron Diffraction Revealed Novel Organometallic Lead Bromide Phases Containing Ferrocene as Redox Switches

“…[ 41,51 ] Nevertheless, especially in hybrid layered systems, besides beam sensitivity, stacking disorder is another difficulty that often requires a combination of several methods such as 3D ED, PXRD, modeling/simulation, and DFT calculations. [ 41,52 ]…”