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

In addition to a
great swelling ability, layered silicates also
allow the functionalization of their interlayer region to form various
robust green materials that are used as CO2 adsorbents,
drug carriers, or catalysts. Here, the unique magadiite structure,
which has resisted elucidation despite many attempts and applications
the material offers, is finally described. A material-specific strategy
allowed the use of 3D electron diffraction which led to the success
of deciphering the atomic structure. In order to enable an ab initio
structure solution of the electron beam sensitive material, a sodium-free
dehydrated form of magadiite was synthetically isolated, and, from
that, it was subsequently possible to derive a structure model for
the sodium form of magadiite, later successfully refined against powder
X-ray diffraction data. Furthermore, a geometry optimization and simulations
of spectroscopic data with DFT methods confirm the obtained crystal
structure of sodium magadiite. These results finally prompted a detailed
description of the layers and of the chemically active interlayer
region and provide a huge impact toward the design of new and more
efficient materials based on functionalized magadiite and related
structures.