Investigating thiouracil adsorption by an iron-doped carbon particle: Analyzing structural, electronic, and QTAIM features

Abstract

This work was performed to examine thiouracil (TU) adsorption by an iron-doped metal carbon particle (MCP) for providing information towards drug delivery purposes. To this aim, four types of TU related compounds were investigated including the parent uracil (U), 2,4-dithiouracil (TU), 2-thiouracil (2TU), and 4-thiouracil (4TU). The MCP model was created by substitution of one iron (Fe) atom instead of one carbon atom of a C20 fullerene-like cage resulting C19Fe model. TU models were relaxed at the Fe region of MCP by considering the separated relaxation processes for each of urea-type and amide-type atoms of pyrimidine ring. Density functional theory (DFT) computations were performed to obtain the optimized structures in addition to evaluation of other related features. The stabilized models indicated that the role of urea-type S atom was significant for formation of strong complexes with the MCP. Various types of energies, molecular orbital features, natural bond orbital (NBO) atomic charges, and quadrupole coupling constants were used for analyzing the models. Furthermore, the quantum theory of atoms in molecules (QTAIM) approach was employed to recognize the strength of interactions of TU@MCP complex models. As a final remark, the obtained results demonstrated the promising role of MCP as a conducting carrier towards drug delivery of TU.