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Updated: Dec 21, 2025
Isothermal Titration Calorimetry for Measuring Macromolecule-Ligand Affinity
Published on: September 7, 2011
DFT analysis of the interaction between Hg2+ and monodentate neutral ligands using NBO, EDA, and QTAIM
Victor Hugo Malamace da Silva1, José Walkimar de Mesquita Carneiro2, Leonardo Moreira da Costa2
1Escola de Engenharia, Universidade Federal Fluminense, Rua Passos da Pátria 156, Niterói, RJ, 24210-253, Brazil. victormalamace@gmail.com.
Abstract:
We report thermodynamic, geometric, and electronic parameters for the interaction between neutral ligands and the [Hg(H2O)]2+ dication, using the B3LYP/6-311 + G(d,p) approach. Gibbs free energies for the interaction were employed to rank the affinity order of the several neutral ligands. To identify the parameters that characterize the affinity between the two fragments, the metal-ligand interaction was analyzed according to the EDA, NBO, and QTAIM decomposition schemes. The phosphine oxide showed the highest affinity for the Hg(H2O)2+ dication, mainly due to the P=O bond polarization. Ligands containing the sulfur atom, characterized by a high covalent component for the metal-ligand interaction, are the following in the interaction order. According to the Gibbs free energy for substitution of one water molecule in the [Hg(H2O)2]2+ complex, the sequence for the affinity order is: phosphine oxide > thioketone > thioesther > lactam > amide > amine > carboxylic acid > thiophene > ketone > esther > thiol > thiocyanate > ammonia > disulfide > aldehyde > ether > haloydrin > alcohol > enol > azide. Graphical abstract Synopsis The interaction between the Hg2+ cation and monodentate ligands containing S, O, or N atoms was evaluated in terms of energetic (bond strength, electrostatic and covalent interactions, donation energy), geometric (metal-ligand distance), electronic (atomic charges, orbital overlap, orbital hybridization) and topologic parameters.
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