Delivery of tioguanine anticancer drug by Fe-doped fullerene cage: DFT evaluation of electronic and structural features

The advantage of employing a model of iron (Fe)-doped carbon-20 fullerene cage (C) for delivery of tioguanine (TG) anticancer drug was investigated in this work by performing density functional theory (DFT) calculations. The models were optimized and corresponding electronic and structural features were evaluated to analyze the model systems of this work. Based on examining relaxation of TG at the C surface, two configurations of TG@C1 and TG@C2 were obtained regarding the orientation of sulfur-mediated TG from six-member ring or fivemember ring towards the Fe-doped region of C surface. The calculations indicated that both models could be stabilized with more favorable features in energy and molecular orbitals for TG@C2 model than TG@C1 model. Further analyses of molecular orbital features also indicated mechanism of bimolecular formations. Additionally, the calculated atomic quadrupole coupling constants (QCC) approved achievements of molecular features to recognize TG@C2 as more favorable model for proposing for further investigations.