Up to this point, all calculations assumed an adsorption of isolated 5-FU in the zeolite pores, neglecting the possible co-adsorption of water. While this is probably a reasonable approximation for highly hydrophobic all-silica zeolites, the framework charge of aluminosilicate zeolites results in an increased hydrophilicity, and co-adsorption of water will be inevitable in many real-world scenarios. In a previous computational study using an analogous computational setup, an adsorption energy of -86 kJ mol -1 was obtained for the adsorption of a single H2O molecule at the framework proton at H-FAU_1H. While this is considerably less negative than the adsorption energy obtained for 5-FU, one needs to consider that the adsorption of water in protonic zeolites usually involves the interaction of a cluster of several H2O molecules with the framework. Hence, a more meaningful comparison can be made by considering the adsorption energy of a (H2O)n cluster having roughly the same size as a single 5-FU molecule. Based on the crystal structure of the most stable polymorph, the molecular volume of 5-FU can be approximated as 121 Å 3 , 92 compared to 32.5 Å 3 for H2O. Thus, a cluster of four H2O molecules should occupy a similar volume as one 5-FU molecule. According to previously reported calculations, the total adsorption energy for such a cluster is on the order of -274 kJ mol -1 (-68.5 kJ mol -1 per H2O), being considerably more negative than the Δ𝐸 , value of -144 kJ mol -1 computed for 5-FU@H-FAU_1H.