eng Abstract: Density functional theory (DFT) studies have contributed to analyze the interaction between chitosan and chitin with Hg(I), Hg(II) and Pb(I), Pb(II) ions in the absence or in the presence of one to three water molecules. All calculations were performed at the M06-2X/LanL2DZ level of theory using Glucosamine and N-acetylglucosamine monomers as models of chitosan and chitin biopolymers, respectively. Geometries of all complexes were optimized, enthalpies and Gibbs free energies of the interactions were calculated. The obtained results suggest that Hg(I) and Pb(I) cations tend to bind to glucosamine at the O4/N5 position with the best stability, while these cations prefer the O3/O4 position in coordinating to N-acetylglucosamine. The most favorable binding positions of these two molecules with Hg(II) and Pb(II) cations are all at the O3/O4 ones. The presence of water molecules slightly affects the most favorable binding configuration, and strongly stabilizes the metallic complexes by forming several hydrogen bonds. Additionally, the Pb(I) complexes are more stable than the Hg(I) ones, whereas the Pb(II) complexes are less stable than the Hg(II) ones. This observation is quite coherent with reported experimental data. Finally, natural bond orbital (NBO) analysis shows that all the metallic cations play as electron acceptors in receiving lone pairs of electron from the heteroatoms of the ligands to their vacant orbitals. http://creativecommons.org/licenses/by-nc-nd/4.0/legalcode application/pdf 1101217 bytes Keywords: Glucosamine; N-acetylglucosamine; Interaction; DFT; Hg; Pb 2018 Jeremić, Svetlana Hien Tran, Thu Marković, Zoran Thi Ngo, Chinh Quang Dao, Duy https://phaidrabg.bg.ac.rs/o:29669 doi:10.1016/j.comptc.2018.06.010 ISSN: 2210-271X Insight into interaction properties between mercury and lead cations with chitosan and chitin: density functional theory studies Computational and Theoretical Chemistry 1138 info:eu-repo/semantics/article