DFT investigation of 5-fluorouracil adsorption on Fe/Mg–N₄ carbon coordination frameworks: mechanistic insights

Pharmaceutical residues like 5-fluorouracil (5-FU) are emerging contaminants in aquatic environments, posing ecological risks. This research utilizes density functional theory (DFT) to examine the adsorption of 5-FU on Fe(II)/Mg(II)-N₄ carbon coordination frameworks (M-N₄-CCFs). Geometry optimization, adsorption energy, and electronic analyses (AIM, NBO) reveal that Fe(II)-N₄-CCFs exhibit stronger adsorption and charge transfer than Mg(II)-N₄-CCFs due to partial covalent Fe–O bonding. Despite calculations being conducted in the gas phase, the trends offer insights into aqueous adsorption mechanisms. The strong affinity of Fe(II)-N₄-CCFs highlights their potential as efficient nanoadsorbents for pharmaceutical removal and environmental remediation.