Solution Equilibria of Holmium(III) and Gadolinium(III) Complexes of Thymoquinone

摘要

The complexing capacities of thymoquinone with trivalent holmium(III) and gadolinium(III) metal ions and their overall stability constants in aqueous solutions were obtained using the HYPERQUAD 2008 program from the pH-potentiometric titration data. The molecular structures of thymoquinone-metal complexes formed in solutions were determined based on some spectral methods, and molecular modeling. The graphic representation of the complex species concentration curves is given by the distribution diagram performed by means of the HySS 2009 modeling program, which furnishes a variety of data presentations, including tables of concentrations of all species present in solution in the selected pH ranges.