(1) AIMD simulations starting from optimised 5-FU@FAU configurations were performed in order to determine internal energies of adsorption Δ𝑈 and to investigate the stability/lability of hydrogen bonds. For this purpose, simulations were run for the 5-FU@FAU configuration, the guest-free zeolite, and for 5-FU in a box, computing three independent trajectories of 12.5 ps (25,000 steps) for each system (four trajectories were computed for 5-FAU@SiO2-FAU, see Results). After discarding the first 2.5 ps as equilibration phase, internal energies of adsorption as well as estimated upper and lower boundary values were computed from the production part of the trajectories. The procedure, which follows earlier work, is described in more detail in section S1.4 of the ESI. For atom combinations of interest, radial distribution functions (RDFs) were calculated for individual trajectories using VMD, and then averaged over all 3 (or 4) trajectories.