The remainder of this article is organised as follows: After describing the structure models and computational details, the stability of a framework-associated octahedral Al environment in the absence and presence of additional H2O molecules (that are not coordinated to the Aloct atom) is investigated with AIMD simulations. Following this, DFT optimisations of models where one 5-FU molecule is coordinated to the Aloct site are performed, allowing the calculation of adsorption energies and an analysis of the local environment of 5-FU. In order to establish a link to experimental findings, infrared (IR) spectra and Al NMR isotropic chemical shifts are computed for selected models. Finally, AIMD simulations of models with Al-coordinated 5-FU in the absence and presence of a hydration shell are carried out, allowing conclusions on the stability of such complexes under conditions relevant for drug delivery applications.