Adsorption of 5-Fluorouracil and Thioguanine drugs into three Zeolitic Imidazolate Frameworks (ZIFs), (ZIF-1, ZIF-3 and ZIF-6) were studied in detail through Monte Carlo (MC) and Molecular Dynamics (MD) simulations. GCMC results showed that the adsorption capacity of 5-Fluorouracil on the studied ZIFs is slightly higher than those of Thioguanine. The order of adsorption capacities of the two studied drugs on ZIFs structures is ZIF-6 > ZIF-3 > ZIF-1, where ZIF-6 shows a higher adsorption capacity for both drugs than the two other ZIFs due to its larger pore volume. Also, the isosteric heats of adsorption of both drugs in ZIF-6 are greater than those of ZIF-3 and ZIF-1. The preferential adsorption sites of 5-Fluorouracil and Thioguanine in ZIF-1 and ZIF-6 are surrounding the cage II (4-membered Zn-imidazolate ring). Finally, the microscopic details of the adsorbates in the studied ZIFs are investigated through radial distribution functions (RDFs) for characteristic atoms of drugs and ZIFs. It was found that the studied drugs preferentially adsorb in the vicinity of the metal site of ZIFs.
