For the design of a methanol-protecting environment, the interactions of guest molecules with the other parts of the framework beyond the active site are crucial. We therefore analyzed the hostguest interactions of the Fe1-MFU-4l(OH) system with the reactants and products. Looking into the NEB paths of reactants and products (N2, CH4 and CH3OH) from the center of the pore to the M or MO site, we observe no barriers (Figures S1, S2 and S5). However, the MFU-4l framework exhibits one peculiarity: Neighboring pores, although lined by the same linkers, exhibit different pore volumes as the anions coordinating to the metal node only point into every second pore, making it smaller than all the surrounding pores (see Figure ). Previously, attempts were made to use this characteristic feature e.g., for H2/D2 sieving in the small pore variant MFU-4. To investigate possible barriers for guest molecules to move through the Fe1-MFU-4l(OH) system, we therefore placed all guest molecules (CH3, CH3OH, CH4, H2O, N2 and N2O) in the center of the small and large cavities and performed NEB calculations between the two differently sized pores (see Figure ). All diffusion calculations used PBE, as adsorption energies do not show a strong functional dependence throughout this work. Resulting NEB paths are given in Figures .