3D ED: an invaluable assistance in new materials discovery

Revolutionizing the field of structural crystallography, 3D ED techniques using parallel beam electron diffraction has reached maturity, providing valuable assistance in the discovery of new materials. This is exemplified here by two recent collaborative works conducted through the METSA French platform (metsa.fr), with CRISMAT serving as the host centre for electron crystallography.

Molten Salts-Driven Discovery of a Polar Mixed-Anion 3D Framework at the Nanoscale: Zn4Si2O7Cl2, Charge Transport and Photoelectrocatalytic Water Splitting, R. Kumar et al., Angew. Chem. Int. Ed. (2023) 62, e2023034. https://doi.org/10.1002/anie.202303487

Precession-assisted 3D ED allowed to solve the structure of Zn4Si2O7Cl2 nanorods, a new polar mixed-anion structure synthesised at the Laboratory of Condensed Matter Chemistry of Paris (LCMCP), affiliated to CNRS and Sorbonne University. Zn4Si2O7Cl2 is built from (ZnO3)2Cl dimers bridged by dimers of corner-sharing SiO4 tetrahedra. This structure brings high chemical and thermal stability, as well as strongly anisotropic hole mobility along its polar axis.

A Robust Ultra-microporous Cationic Aluminium-based Metal-Organic Framework with a Flexible Tetra-carboxylate Linker, S. Nandi et al., Communications Chemistry 6 (2023) 144. https://www.nature.com/articles/s42004-023-00938-x.epdf

Because of the small size of the crystallites (ca. 100-300 nm) and electron beam sensitivity, fast continuous 3D ED (cRED a.k.a microED) has been employed to determine the structure of a new Metal-Organic Framework (MOF) designed at the Institute of Porous Materials (IMAP-Paris), a joint CNRS-ENS-ESPCI laboratory. With a general formula Al18(μ2-OH)24(OH2)12(Cl)6(mdip)6.6H2O, the new MOF MIP-213(Al) is an ordered defected cationic framework whose charge is balanced by the presence of Cl-. This material selectively adsorbs CO2 over nitrogen and possesses high hydrolytic stability.