Mapping of Guest Localization in Mesoporous Silica Particles by Solid-State NMR and <i>Ab Initio</i> Modeling: New Insights into Benzoic Acid and <i>p</i>-Fluorobenzoic Acid Embedded in MCM-41 via Ball Milling

We present a novel strategy for mapping the localization of guest molecules (GMs) in mesoporous materials by combining mechanochemistry with solid-state nuclear magnetic resonance (ssNMR) spectroscopy. To this end, we consider model guest–host systems benzoic acid (BA) and para-fluorobenzoic (4-FBA) embedded MCM-41 material examine recently proposed loading (MeLo) procedure efficient encapsulation molecular species. Application high-resolution NMR experiments (1H 19F NMR) has allowed detection multimodal distribution spectral signals ascribed to GMs. This peculiarity reflects presence distinct ensembles subjected intrinsically different local environments exhibiting dynamical behavior. Furthermore, considerable fraction an amorphous phase been found as byproduct ball-milling. The stability mixture was further checked subjecting samples chemical physical stimuli, detailed interpretation data corroborated theoretical calculations. have undertaken challenge predict spectra GMs@MCM-41 using advanced ab initio dynamics (AIMD) simulations, providing accurate exhaustive analysis spectra. On basis modeling validated against experimental results, find that signal level pore filling, can be both interface fluid species trapped inside pores. confirmed BA@MCM-41 4-FBA@MCM-41 systems. third, linked interstitial space between randomly ordered crystallites, pointing at importance external surface stabilization encapsulated materials. Altogether, consistent methodology presented, paving way more complex nanoconfined