Metal‐organic frameworks (MOFs) are a family of porous solids combining organic and inorganic moieties with tunable porosity. Their structural parameters have converted MOFs into suitable compounds for gas storage or drug delivery. However, despite the excellent crystallinity they tend to exhibit their analysis through transmission electron microscopy is extraordinarily complicated owing to the high instability under the electron beam irradiation. In here, high‐resolution Cs‐corrected STEM imaging was used for the observation of the building units of MIL‐100(Fe), and special attention was paid to the electron beam current. In addition, MIL‐100(Fe) was reacted with AgNO3 through a solid‐state reaction technique, which resulted into the formation of metal nanoparticles on the surface. The incorporation of Ag into the porous network has been also investigated.

Loading of active metals, metal clusters, and/or metal nanoparticles in Metal Organic Frameworks (MOFs) is an emergent field with applications in sensors, catalysis, medicine, and even in the polymeric industry. In the present work, MIL-100(Fe) has been synthesized and reacted with AgNO3 through liquid and incipient wetness, and also through solid-state reaction or solid grinding. The aim of this study is to evaluate whether the MIL-100 would uptake metal particles using a similar principle as that of the ion exchange in zeolites, or else, their inherent humidity would favor the “dissolution” of the metal salt, thus yielding very small metal particles. The immobilization of Ag nanoparticles inside the MOF pores was identified by Cs-corrected scanning transmission electron microscopy (Cs-corrected STEM) techniques.