DFT study on the selective complexation of meso-2,3-dimercaptosuccinic acid with toxic metal ions (Cd2+, Hg2+ and Pb2+) for pharmaceutical and biological applications.

Abstract In this work, density functional theory (DFT) calculations were performed to investigate the complex formation ability of Meso-2,3-dimercaptosuccinic acid (DMSA) with metal ions (Cd2+, Hg2+ and Pb2+) in water. The binding energy values and thermodynamic parameters have been calculated. Natural bond orbital and charge decomposition analyses show an effective charge transfer from the oxygen and sulfur atoms of the DMSA to metal ions. Quantum theory of atoms in molecules analysis reveals that the covalent interactions between DMSA and Pb2+ are the driving force in complex formation, while the non-covalent interactions, mainly, electrostatic interactions play an important role in the complex formation of the DMSA with Cd2+ and Hg2+. Finally, The electronic properties such as highest occupied molecular orbital, lowest unoccupied molecular orbital energies, electronic chemical hardness, electronic chemical potential and global electrophilicity were calculated to get a better insight of molecular properties. Graphical abstract Image Highlights • Charge transfer and stability of [Cd-DMSA], [Hg-DMSA] and [Pb-DMSA] complexes were studied theoretically. • [Pb-DMSA] is the more stable complex than the other complexes. • Charge transfer occurs from the oxygen and sulfur atoms of DMSA to the metal ions. • QTAIM, ELF and LOL analyses confirm that the strongest metal-DMSA interactions are related to [Pb-DMSA] complex. [ABSTRACT FROM AUTHOR]