Atomic-Level Electron Crystallography of Metal–Organic Frameworks Via Resin-Peeled Ultramicrotomy

Electron crystallography offers the potential for ultra-high-resolution diffraction and imaging of materials. However, challenges remain, particularly regarding beam/mechanical sensitivity, severe electron multiple scattering, and the low contrast of light elements in fragile porous organic crystals that often cannot be thinned without compromising their crystallinity. Herein, we develop a method, named resin-peeled ultramicrotomy, to prepare high-crystalline lamella free of embedding resin. By applying crystalline lamellas for 3D electron diffraction, we improve data quality and achieve resolutions up to 0.39 Å. This improvement allows for single-crystal structure determinations of metal-organic frameworks (MOFs) with large unit cells and giant pores─previously unsolved by X-ray and electron diffraction─and resolves ordered/disordered positions of (hydro)oxyl bridging atoms. Moreover, resin-peeled ultramicrotomy enables thinning of 3D MOFs along multiple crystallographic orientations. The further combination with electron ptychography reveals the local structures of 3D MOFs with high resolution and contrast. This advancement opens new avenues for resolving atomic and local structures in soft functional materials.