Theoretical and experimental investigation of complex structures citrate of zinc (II)

• Citrate–metal complexes (Zn2+) were studied by theoretical calculations and ESI-MS.
• The thermodynamic stability of the metal complex was analyzed.
• Complexes present in several biological systems.

The combined use of ESI-MS and theoretical calculations for the determination of zinc:citrate structures are reported. Mass spectrometry allowed to determine the stoichiometry 1:1 and 2:1 of the complexes, corroborating the theoretical calculations. The species found in the ratio 2:1 had their molecular structures readjusted, since the deprotonation of citric acid differed from what was simulated. The thermodynamic stability (ΔH0(aq.)) of the complexes optimized at the B3LYP/LANL2DZ level was more exoenergetic than for the complexes found by the PM6 semi-empirical method.

Structures proposals for the complex citrate–Zn2+ and identified by ESI-MS.Figure optionsDownload as PowerPoint slide